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Sample records for lap adhesive composite

  1. Multitechnique monitoring of fatigue damage in adhesively bonded composite lap-joints

    NASA Astrophysics Data System (ADS)

    Karpenko, Oleksii; Koricho, Ermias; Khomenko, Anton; Dib, Gerges; Haq, Mahmoodul; Udpa, Lalita

    2015-03-01

    The requirement for reduced structural weight has driven the development of adhesively bonded joints. However, a major issue preventing their full acceptance is the initiation of premature failure in the form of a disbond between adherends, mainly due to fatigue, manufacturing flaws or impact damage. This work presents the integrated approach for in-situ monitoring of degradation of the adhesive bond in the GFRP composite lap-joint using ultrasonic guided waves and dynamic measurements from strategically embedded FBG sensors. Guided waves are actuated with surface mounted piezoelectric elements and mode tuning is used to provide high sensitivity to the degradation of the adhesive layer parameters. Composite lap-joints are subjected to fatigue loading, and data from piezoceramic transducers are collected at regular intervals to evaluate the progression of damage. Results demonstrate that quasi-static loading affects guided wave measurements considerably, but FBG sensors can be used to monitor the applied load levels and residual strains in the adhesive bond. The proposed technique shows promise for determining the post-damage stiffness of adhesively bonded joints.

  2. Lamb wave based active damage identification in adhesively bonded composite lap joints

    NASA Astrophysics Data System (ADS)

    Jolly, Prateek

    Bonding composite structures using adhesives offers several advantages over mechanical fastening such as better flow stress, weight saving, improved fatigue resistance and the ability to join dissimilar structures. The hesitation to adopt adhesively bonded composite joints stems from the lack of knowledge regarding damage initiation and propagation mechanisms within the joint. A means of overcoming this hesitation is to continuously monitor damage in the joint. This study proposes a methodology to conduct structural health monitoring (SHM) of an adhesively bonded composite lap joint using acoustic, guided Lamb waves by detecting, locating and predicting the size of damage. Finite element modeling of a joint in both 2D and 3D is used to test the feasibility of the proposed damage triangulation technique. Experimental validation of the methodology is conducted by detecting the presence, location and size of inflicted damage with the use of tuned guided Lamb waves.

  3. A Semi-Analytical Method for Determining the Energy Release Rate of Cracks in Adhesively-Bonded Single-Lap Composite Joints

    NASA Technical Reports Server (NTRS)

    Yang, Charles; Sun, Wenjun; Tomblin, John S.; Smeltzer, Stanley S., III

    2007-01-01

    A semi-analytical method for determining the strain energy release rate due to a prescribed interface crack in an adhesively-bonded, single-lap composite joint subjected to axial tension is presented. The field equations in terms of displacements within the joint are formulated by using first-order shear deformable, laminated plate theory together with kinematic relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. Based on the adhesive stress distributions, the forces at the crack tip are obtained and the strain energy release rate of the crack is determined by using the virtual crack closure technique (VCCT). Additionally, the test specimen geometry from both the ASTM D3165 and D1002 test standards are utilized during the derivation of the field equations in order to correlate analytical models with future test results. The system of second-order differential field equations is solved to provide the adherend and adhesive stress response using the symbolic computation tool, Maple 9. Finite element analyses using J-integral as well as VCCT were performed to verify the developed analytical model. The finite element analyses were conducted using the commercial finite element analysis software ABAQUS. The results determined using the analytical method correlated well with the results from the finite element analyses.

  4. Secreted Listeria adhesion protein (Lap) influences Lap-mediated Listeria monocytogenes paracellular translocation through epithelial barrier.

    PubMed

    Kim, Hyochin; Bhunia, Arun K

    2013-06-24

    Listeria adhesion protein (Lap), an alcohol acetaldehyde dehydrogenase (lmo1634) promotes bacterial paracellular translocation through epithelial cell junctions during gastrointestinal phase of infection. Secreted Lap is critical for pathogenesis and is mediated by SecA2 system; however, if strain dependent variation in Lap secretion would affect L. monocytogenes paracellular translocation through epithelial barrier is unknown. Amounts of Lap secretion were examined in clinical isolates of L. monocytogenes by cell fractionation analysis using Western blot. Quantitative reverse transcriptase PCR (qRT-PCR) was used to verify protein expression profiles. Adhesion and invasion of isolates were analyzed by in vitro Caco-2 cell culture model and paracellular translocation was determined using a trans-well model pre-seeded with Caco-2 cells. Western blot revealed that expression of Lap in whole cell preparation of isolates was very similar; however, cell fractionation analysis indicated variable Lap secretion among isolates. The strains showing high Lap secretion in supernatant exhibited significantly higher adhesion (3.4 - 4.8% vs 1.5 - 2.3%, P < 0.05), invasion and paracellular translocation in Caco-2 cells than the low secreting isolates. In cell wall fraction, Lap level was mostly uniform for both groups, while Lap accumulated in cytosol in low secreting strains indicating that Lap distribution in cellular compartments is a strain-dependent phenomenon, which may be controlled by the protein transport system, SecA2. ΔsecA2 mutants showed significantly reduced paracellular translocation through epithelial barrier (0.48 ± 0.01 vs 0.24 ± 0.02, P < 0.05). qRT-PCR did not show any discernible variation in lap transcript levels in either high or low secreting isolates. This study revealed that secreted Lap is an important determinant in Lap-mediated L. monocytogenes translocation through paracellular route and may serve as an indicator for pathogenic

  5. Secreted Listeria adhesion protein (Lap) influences Lap-mediated Listeria monocytogenes paracellular translocation through epithelial barrier

    PubMed Central

    2013-01-01

    Background Listeria adhesion protein (Lap), an alcohol acetaldehyde dehydrogenase (lmo1634) promotes bacterial paracellular translocation through epithelial cell junctions during gastrointestinal phase of infection. Secreted Lap is critical for pathogenesis and is mediated by SecA2 system; however, if strain dependent variation in Lap secretion would affect L. monocytogenes paracellular translocation through epithelial barrier is unknown. Methods Amounts of Lap secretion were examined in clinical isolates of L. monocytogenes by cell fractionation analysis using Western blot. Quantitative reverse transcriptase PCR (qRT-PCR) was used to verify protein expression profiles. Adhesion and invasion of isolates were analyzed by in vitro Caco-2 cell culture model and paracellular translocation was determined using a trans-well model pre-seeded with Caco-2 cells. Results Western blot revealed that expression of Lap in whole cell preparation of isolates was very similar; however, cell fractionation analysis indicated variable Lap secretion among isolates. The strains showing high Lap secretion in supernatant exhibited significantly higher adhesion (3.4 - 4.8% vs 1.5 - 2.3%, P < 0.05), invasion and paracellular translocation in Caco-2 cells than the low secreting isolates. In cell wall fraction, Lap level was mostly uniform for both groups, while Lap accumulated in cytosol in low secreting strains indicating that Lap distribution in cellular compartments is a strain-dependent phenomenon, which may be controlled by the protein transport system, SecA2. ΔsecA2 mutants showed significantly reduced paracellular translocation through epithelial barrier (0.48 ± 0.01 vs 0.24 ± 0.02, P < 0.05). qRT-PCR did not show any discernible variation in lap transcript levels in either high or low secreting isolates. Conclusion This study revealed that secreted Lap is an important determinant in Lap-mediated L. monocytogenes translocation through paracellular route and may

  6. Review on failure prediction techniques of composite single lap joint

    SciTech Connect

    Ab Ghani, A.F. Rivai, Ahmad

    2016-03-29

    Adhesive bonding is the most appropriate joining method in construction of composite structures. The use of reliable design and prediction technique will produce better performance of bonded joints. Several papers from recent papers and journals have been reviewed and synthesized to understand the current state of the art in this area. It is done by studying the most relevant analytical solutions for composite adherends with start of reviewing the most fundamental ones involving beam/plate theory. It is then extended to review single lap joint non linearity and failure prediction and finally on the failure prediction on composite single lap joint. The review also encompasses the finite element modelling part as tool to predict the elastic response of composite single lap joint and failure prediction numerically.

  7. Failure strength prediction for adhesively bonded single lap joints

    NASA Astrophysics Data System (ADS)

    Rahman, Niat Mahmud

    For adhesively bonded joint, failure strength depends on many factors such as material properties (both adhesive and adherend), specimen geometries, test environments, surface preparation procedures, etc. Failure occurs inside constitutive materials or along joint interfaces. Based on location, adhesively bonded failure mode can be classified as adhesive failure mode, cohesive failure mode and adherend failure mode. Failure mode directly affects the failure strength of joint. For last eight decades, researchers have developed analytical, empirical or semi-empirical methods capable of predicting failure strength for adhesively bonded joints generating either cohesive failure or adherend failure. Applicability of most of the methods is limited to particular cases. In this research, different failure modes for single lap joints (SLJs) were generated experimentally using epoxy based paste adhesive. Based on experimental data and analytical study, simplified failure prediction methods were developed for each failure mode. For adhesive failure mode, it is observed that peel stress distributions concur along interface near crack initiation points. All SLJs for this test endured consistent surface treatments. Geometric parameters of the joints were varied to study their effect on failure strength. Peel stress distributions were calculated using finite analysis (FEA). Based on peel stress distribution near crack initiation point, a failure model is proposed. Numerous analytical, empirical and semi-empirical models are available for predicting failure strengths of SLJs generating cohesive failures. However, most of the methods in the literature failed to capture failure behavior of SLJs having thickness of adhesive layer as variable. Cohesive failure mode was generated experimentally using aluminum as adherend and epoxy adhesive considering thickness of adhesive layers as variable within SLJs. Comparative study was performed among various methods. It was observed that

  8. Adhesive-bonded scarf and stepped-lap joints

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.

    1973-01-01

    Continuum mechanics solutions are derived for the static load-carrying capacity of scarf and stepped-lap adhesive-bonded joints. The analyses account for adhesive plasticity and adherend stiffness imbalance and thermal mismatch. The scarf joint solutions include a simple algebraic formula which serves as a close lower bound, within a small fraction of a per cent of the true answer for most practical geometries and materials. Digital computer programs were developed and, for the stepped-lap joints, the critical adherend and adhesive stresses are computed for each step. The scarf joint solutions exhibit grossly different behavior from that for double-lap joints for long overlaps inasmuch as that the potential bond shear strength continues to increase with indefinitely long overlaps on the scarf joints. The stepped-lap joint solutions exhibit some characteristics of both the scarf and double-lap joints. The stepped-lap computer program handles arbitrary (different) step lengths and thickness and the solutions obtained have clarified potentially weak design details and the remedies. The program has been used effectively to optimize the joint proportions.

  9. Material characterization of structural adhesives in the lap shear mode

    NASA Technical Reports Server (NTRS)

    Sancaktar, E.; Schenck, S. C.

    1983-01-01

    A general method for characterizing structual adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semiempirical and theoretical approaches are used. The semiempirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Two different model adhesives are used in the single lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method.

  10. Listeria monocytogenes uses Listeria adhesion protein (LAP) to promote bacterial transepithelial translocation and induces expression of LAP receptor Hsp60.

    PubMed

    Burkholder, Kristin M; Bhunia, Arun K

    2010-12-01

    Listeria monocytogenes interaction with the intestinal epithelium is a key step in the infection process. We demonstrated that Listeria adhesion protein (LAP) promotes adhesion to intestinal epithelial cells and facilitates extraintestinal dissemination in vivo. The LAP receptor is a stress response protein, Hsp60, but the precise role for the LAP-Hsp60 interaction during Listeria infection is unknown. Here we investigated the influence of physiological stressors and Listeria infection on host Hsp60 expression and LAP-mediated bacterial adhesion, invasion, and transepithelial translocation in an enterocyte-like Caco-2 cell model. Stressors such as heat (41°C), tumor necrosis factor alpha (TNF-α) (100 U), and L. monocytogenes infection (10(4) to 10(6) CFU/ml) significantly (P < 0.05) increased plasma membrane and intracellular Hsp60 levels in Caco-2 cells and consequently enhanced LAP-mediated L. monocytogenes adhesion but not invasion of Caco-2 cells. In transepithelial translocation experiments, the wild type (WT) exhibited 2.7-fold more translocation through Caco-2 monolayers than a lap mutant, suggesting that LAP is involved in transepithelial translocation, potentially via a paracellular route. Short hairpin RNA (shRNA) suppression of Hsp60 in Caco-2 cells reduced WT adhesion and translocation 4.5- and 3-fold, respectively, while adhesion remained unchanged for the lap mutant. Conversely, overexpression of Hsp60 in Caco-2 cells enhanced WT adhesion and transepithelial translocation, but not those of the lap mutant. Furthermore, initial infection with a low dosage (10(6) CFU/ml) of L. monocytogenes increased plasma membrane and intracellular expression of Hsp60 significantly, which rendered Caco-2 cells more susceptible to subsequent LAP-mediated adhesion and translocation. These data provide insight into the role of LAP as a virulence factor during intestinal epithelial infection and pose new questions regarding the dynamics between the host stress response

  11. Nonlinear Analysis of Bonded Composite Tubular Lap Joints

    NASA Technical Reports Server (NTRS)

    Oterkus, E.; Madenci, E.; Smeltzer, S. S., III; Ambur, D. R.

    2005-01-01

    The present study describes a semi-analytical solution method for predicting the geometrically nonlinear response of a bonded composite tubular single-lap joint subjected to general loading conditions. The transverse shear and normal stresses in the adhesive as well as membrane stress resultants and bending moments in the adherends are determined using this method. The method utilizes the principle of virtual work in conjunction with nonlinear thin-shell theory to model the adherends and a cylindrical shear lag model to represent the kinematics of the thin adhesive layer between the adherends. The kinematic boundary conditions are imposed by employing the Lagrange multiplier method. In the solution procedure, the displacement components for the tubular joint are approximated in terms of non-periodic and periodic B-Spline functions in the longitudinal and circumferential directions, respectively. The approach presented herein represents a rapid-solution alternative to the finite element method. The solution method was validated by comparison against a previously considered tubular single-lap joint. The steep variation of both peeling and shearing stresses near the adhesive edges was successfully captured. The applicability of the present method was also demonstrated by considering tubular bonded lap-joints subjected to pure bending and torsion.

  12. Nonlinear Analysis of Bonded Composite Tubular Lap Joints

    NASA Technical Reports Server (NTRS)

    Oterkus, E.; Madenci, E.; Smeltzer, S. S., III; Ambur, D. R.

    2005-01-01

    The present study describes a semi-analytical solution method for predicting the geometrically nonlinear response of a bonded composite tubular single-lap joint subjected to general loading conditions. The transverse shear and normal stresses in the adhesive as well as membrane stress resultants and bending moments in the adherends are determined using this method. The method utilizes the principle of virtual work in conjunction with nonlinear thin-shell theory to model the adherends and a cylindrical shear lag model to represent the kinematics of the thin adhesive layer between the adherends. The kinematic boundary conditions are imposed by employing the Lagrange multiplier method. In the solution procedure, the displacement components for the tubular joint are approximated in terms of non-periodic and periodic B-Spline functions in the longitudinal and circumferential directions, respectively. The approach presented herein represents a rapid-solution alternative to the finite element method. The solution method was validated by comparison against a previously considered tubular single-lap joint. The steep variation of both peeling and shearing stresses near the adhesive edges was successfully captured. The applicability of the present method was also demonstrated by considering tubular bonded lap-joints subjected to pure bending and torsion.

  13. How to obtain the adhesive strength for double lap joint by using single lap joint

    NASA Astrophysics Data System (ADS)

    Noda, N. A.; Li, R.; Sano, Y.; Takase, Y.; Takaki, R.; Miyazaki, T.

    2017-05-01

    The testing method of adhesive strength of lap joint is prescribed in Japanese Industrial Standard (JIS K6850). However, it has been reported that the strength of double lap joint (DLJ) is about two times larger than the one of single lap joint (SLJ). Therefore, suitable testing method has been required from industries. In this study, the equivalent conditions of strength for SLJ and DLJ are investigated in terms of the intensity of singular stress field (ISSF) appearing at the interface end. First, in order to minimize the bend effect for SLJ, the effect of the specimen geometry on ISSF and deformation angle at the interface corner is considered under the same adhesive geometry and load P. It is found that the minimum ISSF of SLJ can be obtained when the adherend thickness t 1 is large enough, and the deformation angle at interface corner is also smallest when adherend thickness t 1 is large enough. Therefore, it is necessary to use the specimen with thicker adherend thickness. Then, the equivalent conditions of strength for SLJ and DLJ is investigated by changing adherend thickness. The results show that the strength of the DLJ in JIS ( t 1 = 1.5mm) can be obtained by using the SLJ with adherend thickness t 1 = 7mm. When the adherend thickness t 1 ≥ 25mm, the strength of SLJ is nearly equal to that of DLJ.

  14. Lap Shear Testing of Candidate Radiator Panel Adhesives

    NASA Technical Reports Server (NTRS)

    Ellis, David; Briggs, Maxwell; McGowan, Randy

    2013-01-01

    During testing of a subscale radiator section used to develop manufacturing techniques for a full-scale radiator panel, the adhesive bonds between the titanium heat pipes and the aluminum face sheets failed during installation and operation. Analysis revealed that the thermal expansion mismatch between the two metals resulted in relatively large shear stresses being developed even when operating the radiator at moderate temperatures. Lap shear testing of the adhesive used in the original joints demonstrated that the two-part epoxy adhesive fell far short of the strength required. A literature review resulted in several candidate adhesives being selected for lap shear joint testing at room temperature and 398 K, the nominal radiator operating temperature. The results showed that two-part epoxies cured at room and elevated temperatures generally did not perform well. Epoxy film adhesives cured at elevated temperatures, on the other hand, did very well with most being sufficiently strong to cause yielding in the titanium sheet used for the joints. The use of an epoxy primer generally improved the strength of the joint. Based upon these results, a new adhesive was selected for the second subscale radiator section.

  15. Nonlinear Analysis of Bonded Composite Single-LAP Joints

    NASA Technical Reports Server (NTRS)

    Oterkus, E.; Barut, A.; Madenci, E.; Smeltzer, S. S.; Ambur, D. R.

    2004-01-01

    This study presents a semi-analytical solution method to analyze the geometrically nonlinear response of bonded composite single-lap joints with tapered adherend edges under uniaxial tension. The solution method provides the transverse shear and normal stresses in the adhesive and in-plane stress resultants and bending moments in the adherends. The method utilizes the principle of virtual work in conjunction with von Karman s nonlinear plate theory to model the adherends and the shear lag model to represent the kinematics of the thin adhesive layer between the adherends. Furthermore, the method accounts for the bilinear elastic material behavior of the adhesive while maintaining a linear stress-strain relationship in the adherends. In order to account for the stiffness changes due to thickness variation of the adherends along the tapered edges, their in-plane and bending stiffness matrices are varied as a function of thickness along the tapered region. The combination of these complexities results in a system of nonlinear governing equilibrium equations. This approach represents a computationally efficient alternative to finite element method. Comparisons are made with corresponding results obtained from finite-element analysis. The results confirm the validity of the solution method. The numerical results present the effects of taper angle, adherend overlap length, and the bilinear adhesive material on the stress fields in the adherends, as well as the adhesive, of a single-lap joint

  16. Numerical solutions for heat flow in adhesive lap joints

    NASA Technical Reports Server (NTRS)

    Howell, P. A.; Winfree, William P.

    1992-01-01

    The present formulation for the modeling of heat transfer in thin, adhesively bonded lap joints precludes difficulties associated with large aspect ratio grids required by standard FEM formulations. This quasi-static formulation also reduces the problem dimensionality (by one), thereby minimizing computational requirements. The solutions obtained are found to be in good agreement with both analytical solutions and solutions from standard FEM programs. The approach is noted to yield a more accurate representation of heat-flux changes between layers due to a disbond.

  17. Adhesive-bonded double-lap joints. [analytical solutions for static load carrying capacity

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.

    1973-01-01

    Explicit analytical solutions are derived for the static load carrying capacity of double-lap adhesive-bonded joints. The analyses extend the elastic solution Volkersen and cover adhesive plasticity, adherend stiffness imbalance and thermal mismatch between the adherends. Both elastic-plastic and bi-elastic adhesive representations lead to the explicit result that the influence of the adhesive on the maximum potential bond strength is defined uniquely by the strain energy in shear per unit area of bond. Failures induced by peel stresses at the ends of the joint are examined. This failure mode is particularly important for composite adherends. The explicit solutions are sufficiently simple to be used for design purposes

  18. SHM of single lap adhesive joints using subharmonic frequencies

    NASA Astrophysics Data System (ADS)

    Ginzburg, D.; Ciampa, F.; Scarselli, G.; Meo, M.

    2017-10-01

    The increased usage of adhesive bonding as a joining method in modern aerospace components has led to developing reliable ultrasonic health monitoring systems for detection of regions of poor adhesion. Nonlinear acousto-ultrasonic techniques based on higher harmonics and subharmonic frequencies have shown to be sensitive to the detection of micro-voids and disbonds. Nonlinear resonance properties of disbonds generate various nonlinear phenomena such as self-modulation, subharmonics, hysteresis and so on. By exploiting the local natures of these phenomena, this paper demonstrates the use of subharmonics for detection and imaging of flaws in bonded structures. To optimise the experimental testing a two-dimensional analytical model and a three-dimensional finite element analysis simulation were developed for understanding the generation of nonlinear elastic effects with emphasis on subharmonic frequency components. The proposed analytical model qualitatively described the generation of subharmonics but also higher harmonics due to the nonlinear intermodulation of the driving and resonance frequencies associated with the disbonded region. The numerical model was developed by modifying the user defined cohesive element formulation with a bi-linear traction-displacement relationship in order to simulate the interaction of elastic waves with the structural disbond. Whilst the analytical model supported the selection of the driving frequency, the numerical one successfully predicted the generation of subharmonic frequencies originating in the disbonded area. Experimental tests were conducted on a disbonded single lap joint structure using surface-bonded piezoelectric transducers and a laser-Doppler vibrometer, and allowed to validate the analytical and numerical results. It was clearly demonstrated that the nonlinear resonance effects in the form of subharmonics could be used to discriminate reliably regions of poor adhesion in bonded structures. This work can lead to new

  19. Listeria monocytogenes Uses Listeria Adhesion Protein (LAP) To Promote Bacterial Transepithelial Translocation and Induces Expression of LAP Receptor Hsp60▿

    PubMed Central

    Burkholder, Kristin M.; Bhunia, Arun K.

    2010-01-01

    Listeria monocytogenes interaction with the intestinal epithelium is a key step in the infection process. We demonstrated that Listeria adhesion protein (LAP) promotes adhesion to intestinal epithelial cells and facilitates extraintestinal dissemination in vivo. The LAP receptor is a stress response protein, Hsp60, but the precise role for the LAP-Hsp60 interaction during Listeria infection is unknown. Here we investigated the influence of physiological stressors and Listeria infection on host Hsp60 expression and LAP-mediated bacterial adhesion, invasion, and transepithelial translocation in an enterocyte-like Caco-2 cell model. Stressors such as heat (41°C), tumor necrosis factor alpha (TNF-α) (100 U), and L. monocytogenes infection (104 to 106 CFU/ml) significantly (P < 0.05) increased plasma membrane and intracellular Hsp60 levels in Caco-2 cells and consequently enhanced LAP-mediated L. monocytogenes adhesion but not invasion of Caco-2 cells. In transepithelial translocation experiments, the wild type (WT) exhibited 2.7-fold more translocation through Caco-2 monolayers than a lap mutant, suggesting that LAP is involved in transepithelial translocation, potentially via a paracellular route. Short hairpin RNA (shRNA) suppression of Hsp60 in Caco-2 cells reduced WT adhesion and translocation 4.5- and 3-fold, respectively, while adhesion remained unchanged for the lap mutant. Conversely, overexpression of Hsp60 in Caco-2 cells enhanced WT adhesion and transepithelial translocation, but not those of the lap mutant. Furthermore, initial infection with a low dosage (106 CFU/ml) of L. monocytogenes increased plasma membrane and intracellular expression of Hsp60 significantly, which rendered Caco-2 cells more susceptible to subsequent LAP-mediated adhesion and translocation. These data provide insight into the role of LAP as a virulence factor during intestinal epithelial infection and pose new questions regarding the dynamics between the host stress response and

  20. Screening Adhesively Bonded Single-Lap-Joint Testing Results Using Nonlinear Calculation Parameters

    DTIC Science & Technology

    2012-03-01

    versus displacement response for single-lap-joints bonded with damage-tolerant adhe- sives, such the polyurea adhesive plotted in Figure 2, is much...displacement response for a single-lap-joint bonded with a polyurea adhesive. Complex x-y plots are commonly fitted using the Levenberg-Marquardt...expected decrease in maximum strength for the polyurea in compar- ison to the epoxy, which could have been obtained using a traditional analysis approach

  1. Single-cycle and fatigue strengths of adhesively bonded lap joints

    SciTech Connect

    Metzinger, K.E.; Guess, T.R.

    1998-12-31

    This study considers a composite-to-steel tubular lap joint in which failure typically occurs when the adhesive debonds from the steel adherend. The same basic joint was subjected to compressive and tensile axial loads (single-cycle) as well as bending loads (fatigue). The purpose of these tests was to determine whether failure is more dependent on the plastic strain or the peel stress that develops in the adhesive. For the same joint, compressive and tensile loads of the same magnitude will produce similar plastic strains but peel stresses of opposite signs in the adhesive. In the axial tests, the tensile strengths were much greater than the compressive strengths - indicating that the peel stress is key to predicting the single-cycle strengths. To determine the key parameter(s) for predicting high-cycle fatigue strengths, a test technique capable of subjecting a specimen to several million cycles per day was developed. In these bending tests, the initial adhesive debonding always occurred on the compressive side. This result is consistent with the single-cycle tests, although not as conclusive due to the limited number of tests. Nevertheless, a fatigue test method has been established and future tests are planned.

  2. Fatigue Damage Monitoring of a Composite Step Lap Joint Using Distributed Optical Fibre Sensors.

    PubMed

    Wong, Leslie; Chowdhury, Nabil; Wang, John; Chiu, Wing Kong; Kodikara, Jayantha

    2016-05-14

    Over the past few decades, there has been a considerable interest in the use of distributed optical fibre sensors (DOFS) for structural health monitoring of composite structures. In aerospace-related work, health monitoring of the adhesive joints of composites has become more significant, as they can suffer from cracking and delamination, which can have a significant impact on the integrity of the joint. In this paper, a swept-wavelength interferometry (SWI) based DOFS technique is used to monitor the fatigue in a flush step lap joint composite structure. The presented results will show the potential application of distributed optical fibre sensor for damage detection, as well as monitoring the fatigue crack growth along the bondline of a step lap joint composite structure. The results confirmed that a distributed optical fibre sensor is able to enhance the detection of localised damage in a structure.

  3. Fatigue Damage Monitoring of a Composite Step Lap Joint Using Distributed Optical Fibre Sensors

    PubMed Central

    Wong, Leslie; Chowdhury, Nabil; Wang, John; Chiu, Wing Kong; Kodikara, Jayantha

    2016-01-01

    Over the past few decades, there has been a considerable interest in the use of distributed optical fibre sensors (DOFS) for structural health monitoring of composite structures. In aerospace-related work, health monitoring of the adhesive joints of composites has become more significant, as they can suffer from cracking and delamination, which can have a significant impact on the integrity of the joint. In this paper, a swept-wavelength interferometry (SWI) based DOFS technique is used to monitor the fatigue in a flush step lap joint composite structure. The presented results will show the potential application of distributed optical fibre sensor for damage detection, as well as monitoring the fatigue crack growth along the bondline of a step lap joint composite structure. The results confirmed that a distributed optical fibre sensor is able to enhance the detection of localised damage in a structure. PMID:28773496

  4. Material characterization of structural adhesives in the lap shear mode. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Schenck, S. C.; Sancaktar, E.

    1983-01-01

    A general method for characterizing structural adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semi-empirical and theoretical approaches are used. The semi-empirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Three different model adhesives are used in the simple lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method.

  5. Highly Porous and Compositionally Intermediate Ordinary Chondrite LAP 031047

    NASA Astrophysics Data System (ADS)

    Wittmann, A.; Kring, D. A.; Friedrich, J. M.; Troiano, J.; Macke, R. J.; Britt, D. T.; Swindle, T. D.; Weirich, J. R.; Rumble, D.

    2010-03-01

    LAP 031047 is a highly porous ordinary chondrite with a very young Ar-Ar age, and oxygen isotopic, and bulk and silicate mineral composition intermediate between H- and L-chondrites: Shock-lithified debris of a distinct ordinary chondrite asteroid?

  6. Lap Shear and Impact Testing of Ochre and Beeswax in Experimental Middle Stone Age Compound Adhesives.

    PubMed

    Kozowyk, P R B; Langejans, G H J; Poulis, J A

    2016-01-01

    The production of compound adhesives using disparate ingredients is seen as some of the best evidence of advanced cognition outside of the use of symbolism. Previous field and laboratory testing of adhesives has shown the complexities involved in creating an effective Middle Stone Age glue using Acacia gum. However, it is currently unclear how efficient different adhesive recipes are, how much specific ingredients influence their performance, and how difficult it may have been for those ingredients to be combined to maximum effect. We conducted a series of laboratory-based lap shear and impact tests, following modern adhesion testing standards, to determine the efficacy of compound adhesives, with particular regard to the ingredient ratios. We tested rosin (colophony) and gum adhesives, containing additives of beeswax and ochre in varying ratios. During both lap shear and impact tests compound rosin adhesives performed better than single component rosin adhesives, and pure acacia gum was the strongest. The large difference in performance between each base adhesive and the significant changes in performance that occur due to relatively small changes in ingredient ratios lend further support to the notion that high levels of skill and knowledge were required to consistently produce the most effective adhesives.

  7. Lap Shear and Impact Testing of Ochre and Beeswax in Experimental Middle Stone Age Compound Adhesives

    PubMed Central

    2016-01-01

    The production of compound adhesives using disparate ingredients is seen as some of the best evidence of advanced cognition outside of the use of symbolism. Previous field and laboratory testing of adhesives has shown the complexities involved in creating an effective Middle Stone Age glue using Acacia gum. However, it is currently unclear how efficient different adhesive recipes are, how much specific ingredients influence their performance, and how difficult it may have been for those ingredients to be combined to maximum effect. We conducted a series of laboratory-based lap shear and impact tests, following modern adhesion testing standards, to determine the efficacy of compound adhesives, with particular regard to the ingredient ratios. We tested rosin (colophony) and gum adhesives, containing additives of beeswax and ochre in varying ratios. During both lap shear and impact tests compound rosin adhesives performed better than single component rosin adhesives, and pure acacia gum was the strongest. The large difference in performance between each base adhesive and the significant changes in performance that occur due to relatively small changes in ingredient ratios lend further support to the notion that high levels of skill and knowledge were required to consistently produce the most effective adhesives. PMID:26983080

  8. Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

    SciTech Connect

    Ghazali, Habibah; Ye, Lin; Zhang, Ming-Qiu

    2016-03-09

    The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

  9. Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

    NASA Astrophysics Data System (ADS)

    Ghazali, Habibah; Ye, Lin; Zhang, Ming-Qiu

    2016-03-01

    The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

  10. Characterization of fatigue damage in adhesively bonded lap joints through dynamic, full-spectral interrogation of fiber Bragg grating sensors: 2. Simulations

    NASA Astrophysics Data System (ADS)

    Webb, S.; Shin, P.; Peters, K.; Zikry, M. A.; Stan, N.; Chadderdon, S.; Selfridge, R.; Schultz, S.

    2014-02-01

    In this paper, we simulate the response of fiber Bragg grating (FBG) sensors embedded in the adhesive layer of a composite lap that is subjected to harmonic excitation. To simulate accumulated fatigue damage at the adhesive layer, two forms of numerical nonlinearities are introduced into the model: (1) progressive plastic deformation of the adhesive and (2) changing the boundary of an interfacial defect at the adhesive layer across the overlap shear area. The simulation results are compared with previous measurements of the dynamic, full-spectral response of such FBG sensors for condition monitoring of the lap joint. Short-time Fourier transforms (STFT) of the locally extracted axial strain time histories reveal a transition to nonlinear behavior of the composite lap joint by means of intermittent frequencies that were observed in the experimental measurements and are not associated with the external excitation. The simulation results verify that the nonlinear changes in measured dynamic FBG responses are due to the progression of damage in the lap joint.

  11. Effect of preforming adherends on static and fatigue strength of bonded composite single-lap joints

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.

    1984-01-01

    An analytical and experimental investigation was conducted on bonded composite single-lap joints with the adherends performed to reduce the angle between the line of action of the applied in-plane force and the bondline. A classical closed-form solution was used to analyze the composite joints with various preform angles and overlap lengths. The adherends of the test specimens were preformed before bonding, during the layup and curing process. Static tests were conducted for preform angles of 0, 5, 10, and 15 deg and overlap lengths of 0.75, 1.75, 2.75, and 3.75 in. A limited fatigue study was conducted for specimens with a 2.75-in. overlap and a preform angle of 5 deg. Results of the analysis showed that preforming the adherends of bonded composite single-lap joints significantly reduced the shear and peel stress concentrations in the adhesive. Experimental results showed that preforming the adherends significantly increased their static and fatigue strength and thus increased the load level for which bonded composite single-lap joints can be designed.

  12. A Single-Lap Joint Adhesive Bonding Optimization Method Using Gradient and Genetic Algorithms

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S., III; Finckenor, Jeffrey L.

    1999-01-01

    A natural process for any engineer, scientist, educator, etc. is to seek the most efficient method for accomplishing a given task. In the case of structural design, an area that has a significant impact on the structural efficiency is joint design. Unless the structure is machined from a solid block of material, the individual components which compose the overall structure must be joined together. The method for joining a structure varies depending on the applied loads, material, assembly and disassembly requirements, service life, environment, etc. Using both metallic and fiber reinforced plastic materials limits the user to two methods or a combination of these methods for joining the components into one structure. The first is mechanical fastening and the second is adhesive bonding. Mechanical fastening is by far the most popular joining technique; however, in terms of structural efficiency, adhesive bonding provides a superior joint since the load is distributed uniformly across the joint. The purpose of this paper is to develop a method for optimizing single-lap joint adhesive bonded structures using both gradient and genetic algorithms and comparing the solution process for each method. The goal of the single-lap joint optimization is to find the most efficient structure that meets the imposed requirements while still remaining as lightweight, economical, and reliable as possible. For the single-lap joint, an optimum joint is determined by minimizing the weight of the overall joint based on constraints from adhesive strengths as well as empirically derived rules. The analytical solution of the sin-le-lap joint is determined using the classical Goland-Reissner technique for case 2 type adhesive joints. Joint weight minimization is achieved using a commercially available routine, Design Optimization Tool (DOT), for the gradient solution while an author developed method is used for the genetic algorithm solution. Results illustrate the critical design variables

  13. A Single-Lap Joint Adhesive Bonding Optimization Method Using Gradient and Genetic Algorithms

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S., III; Finckenor, Jeffrey L.

    1999-01-01

    A natural process for any engineer, scientist, educator, etc. is to seek the most efficient method for accomplishing a given task. In the case of structural design, an area that has a significant impact on the structural efficiency is joint design. Unless the structure is machined from a solid block of material, the individual components which compose the overall structure must be joined together. The method for joining a structure varies depending on the applied loads, material, assembly and disassembly requirements, service life, environment, etc. Using both metallic and fiber reinforced plastic materials limits the user to two methods or a combination of these methods for joining the components into one structure. The first is mechanical fastening and the second is adhesive bonding. Mechanical fastening is by far the most popular joining technique; however, in terms of structural efficiency, adhesive bonding provides a superior joint since the load is distributed uniformly across the joint. The purpose of this paper is to develop a method for optimizing single-lap joint adhesive bonded structures using both gradient and genetic algorithms and comparing the solution process for each method. The goal of the single-lap joint optimization is to find the most efficient structure that meets the imposed requirements while still remaining as lightweight, economical, and reliable as possible. For the single-lap joint, an optimum joint is determined by minimizing the weight of the overall joint based on constraints from adhesive strengths as well as empirically derived rules. The analytical solution of the sin-le-lap joint is determined using the classical Goland-Reissner technique for case 2 type adhesive joints. Joint weight minimization is achieved using a commercially available routine, Design Optimization Tool (DOT), for the gradient solution while an author developed method is used for the genetic algorithm solution. Results illustrate the critical design variables

  14. Monitoring of fatigue damage in composite lap-joints using guided waves and FBG sensors

    NASA Astrophysics Data System (ADS)

    Karpenko, Oleksii; Khomenko, Anton; Koricho, Ermias; Haq, Mahmoodul; Udpa, Lalita

    2016-02-01

    Adhesive bonding is being increasingly employed in many applications as it offers possibility of light-weighting and efficient multi-material joining along with reduction in time and cost of manufacturing. However, failure initiation and progression in critical components like joints, specifically in fatigue loading is not well understood, which necessitates reliable NDE and SHM techniques to ensure structural integrity. In this work, concurrent guided wave (GW) and fiber Bragg grating (FBG) sensor measurements were used to monitor fatigue damage in adhesively bonded composite lap-joints. In the present set-up, one FBG sensor was strategically embedded in the adhesive bond-line of a lap-joint, while two other FBGs were bonded on the surface of the adherends. Full spectral responses of FBG sensors were collected and compared at specific intervals of fatigue loading. In parallel, guided waves were actuated and sensed using PZT wafers mounted on the composite adherends. Experimental results demonstrated that time-of-flight (ToF) of the fundamental modes transmitted through the bond-line and spectral response of FBG sensors were sensitive to fatigue loading and damage. Combination of guided wave and FBG measurements provided the desired redundancy and synergy in the data to evaluate the degradation in bond-line properties. Measurements taken in the presence of continuously applied load replicated the in-situ/service conditions. The approach shows promise in understanding the behavior of bonded joints subjected to complex loading.

  15. Progressive damage in single lap countersunk composite joints

    NASA Astrophysics Data System (ADS)

    Chishti, Maajid; Wang, Chun Hui; Thomson, Rodney S.; Orifici, Adrian

    2010-06-01

    This paper presents an experimental and computational investigation of the influences of countersink and bolt torque on the progressive failure of single-lap composite joint. Using the Abaqus® software, delamination damage and ply fracture are modelled using cohesive element approach and continuum damage mechanics method, respectively. The model is first validated against a filled-hole tension test to calibrate the composite damage model. Comparison with the experimental results indicates that the computational model is capable of accurately predicting the joint strength and the damage progression process.

  16. Testing composite-to-metal tubular lap joints

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.; Slavin, A.M.

    1993-11-01

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  17. Characterization of fatigue damage in adhesively bonded lap joints through dynamic, full-spectral interrogation of fiber Bragg grating sensors: 1. Experiments

    NASA Astrophysics Data System (ADS)

    Webb, S.; Shin, P.; Peters, K.; Zikry, M. A.; Stan, N.; Chadderdon, S.; Selfridge, R.; Schultz, S.

    2014-02-01

    In this study we measure the in situ response of a fiber Bragg grating (FBG) sensor embedded in the adhesive layer of a single composite lap joint, subjected to harmonic excitation after fatigue loading. After a fully reversed cyclic fatigue loading is applied to the composite lap joint, the full-spectral response of the sensor is interrogated at 100 kHz during two loading conditions: with and without an added harmonic excitation. The full-spectral information avoided dynamic measurement errors often experienced using conventional peak wavelength and edge filtering techniques. The short-time Fourier transform (STFT) is computed for the extracted peak wavelength information to reveal time-dependent frequencies and amplitudes of the dynamic FBG sensor response. The dynamic response of the FBG sensor indicated a transition to strong nonlinear dynamic behavior as fatigue-induced damage progressed. The ability to measure the dynamic response of the lap joint through sensors embedded in the adhesive layer can provide in situ monitoring of the lap joint condition.

  18. Analysis of interface cracks in adhesively bonded lap shear joints, part 4

    NASA Technical Reports Server (NTRS)

    Wang, S. S.; Yau, J. F.

    1981-01-01

    Conservation laws of elasticity for nonhomogeneous materials were developed and were used to study the crack behavior in adhesively bonded lap shear joints. By using these laws and the fundamental relationships in fracture mechanics of interface cracks, the problem is reduced to a pair of linear algebraic equations, and stress intensity solutions can be determined directly by information extracted from the far field. The numerical results obtained show that: (1) in the lap-shear joint with a given adherend, the opening-mode stress intensity factor, (K sub 1) is always larger than that of the shearing-mode (K sub 2); (2) (K sub 1) is not sensitive to adherent thickness abut (K sub 2) increases rapidly with increasing thickness; and (3) (K sub 1) and (K sub 2) increase simultaneously as the interfacial crack length increases.

  19. Low frequency ultrasonic nondestructive inspection of aluminum/adhesive fuselage lap splices

    SciTech Connect

    Patton, Thadd

    1994-01-04

    This thesis is a collection of research efforts in ultrasonics, conducted at the Center for Aviation Systems Reliability located at Iowa State University, as part of the Federal Aviation Administration`s ``Aging Aircraft Program.`` The research was directed toward the development of an ultrasonic prototype to inspect the aluminum/adhesive fuselage lap splices found on 1970`s vintage Boeing passenger aircraft. The ultrasonic prototype consists of a normal incidence, low frequency inspection technique, and a scanning adapter that allows focused immersion transducers to be operated in a direct contact manner in any inspection orientation, including upside-down. The inspection technique uses a computer-controlled data acquisition system to produce a C-scan image of a radio frequency (RF) waveform created by a low frequency, broadband, focused beam transducer, driven with a spike voltage pulser. C-scans produced by this technique are color representations of the received signal`s peak-to-peak amplitude (voltage) taken over an (x, y) grid. Low frequency, in this context, refers to a wavelength that is greater than the lap splice`s layer thicknesses. With the low frequency technique, interface echoes of the lap splice are not resolved and gating of the signal is unnecessary; this in itself makes the technique simple to implement and saves considerable time in data acquisition. Along with the advantages in data acquisition, the low frequency technique is relatively insensitive to minor surface curvature and to ultrasonic interference effects caused by adhesive bondline thickness variations in the lap splice.

  20. Chaotic and ambient vibration analysis of composite lap joint damage

    NASA Astrophysics Data System (ADS)

    Pecora, Lou; Nichols, Jon; Seaver, Mark; Trickey, Steve; Motley, Sara

    2007-04-01

    We examined strain time series from fiber Bragg gratings sensors located in various positions on a composite material beam attached to a steel plate by a lap joint. The beam was vibrated using both broad-band chaotic signals (Lorenz system), and a narrow band signal conforming to the Pierson-Moskowitz frequency distribution for wave height (ambient excitation). The system was damaged by decreasing the torque on instrumented bolts in the lap joint from very tight all the way through to a joint with a gap and slippage. We analyzed the strain data by reconstructing the attractor of the system in the case of chaotic forcing and a pseudo-attractor in the case of sea-wave forcing. Using the highest torque case as an "undamaged" baseline, we calculated the continuity statistic between the baseline attractor and the attractors of the various damage levels for both forcing cases. We show where one can and cannot say that the functional relationship between the attractors changes and how those changes are related to damage levels.

  1. Single-Lap-Joint Screening of Hysol EA 9309NA Epoxy Adhesive

    DTIC Science & Technology

    2017-05-10

    standardized bonded single lap joints. Materials pedigree information, specifically the reported composition information for hazardous components, is... resin to 23 parts curing agent by weight using a FlackTek Inc. (Hauschild Germany) model DAC 400 Speedmixer for 2 min at 2000 revolutions per minute...vitrifying into a glass and quenching further chemical reactions between the epoxy resin and amine curing agent.14–17 To test this hypothesis of

  2. Shear Strength of Single Lap Joint Aluminium-Thermoplastic Natural Rubber (Al-TPNR) Laminated Composite

    NASA Astrophysics Data System (ADS)

    Muzakkar, M. Z.; Ahmad, S.; Yarmo, M. A.; Jalar, A.; Bijarimi, M.

    2013-04-01

    In this work, we studied the effect of surface treatment on the aluminium surface and a coupling agent to improve adhesion between aluminium with organic polymer. Thermoplastic natural rubber (TPNR) matrix was prepared by melt blending of natural rubber (NR), liquid natural rubber (LNR) compatibilizer, linear low density polyethylene (LLDPE) and polyethylene grafted maleic anhydride (PE-g-MAH). The PEgMAH concentration used was varied from 0% - 25%. In addition, the aluminium surface was pre-treated with 3-glycidoxy propyl trimethoxy silane (3-GPS) to enhance the mechanical properties of laminated composite. It was found that the shear strength of single lap joint Al-TPNR laminated composite showing an increasing trend as a function of PE-g-MAH contents for the 3-GPS surface treated aluminium. Moreover, the scanning electron microscope (SEM) revealed that the strength improvement was associated with the chemical state of the compound involved.

  3. Wood Composite Adhesives

    NASA Astrophysics Data System (ADS)

    Gomez-Bueso, Jose; Haupt, Robert

    The global environment, in which phenolic resins are being used for wood composite manufacture, has changed significantly during the last decade. This chapter reviews trends that are driving the use and consumption of phenolic resins around the world. The review begins with recent data on volume usage and regional trends, followed by an analysis of factors affecting global markets. In a section on environmental factors, the impact of recent formaldehyde emission regulations is discussed. The section on economics introduces wood composite production as it relates to the available adhesive systems, with special emphasis on the technical requirement to improve phenolic reactivity. Advances in composite process technology are introduced, especially in regard to the increased demands the improvements place upon adhesive system performance. The specific requirements for the various wood composite families are considered in the context of adhesive performance needs. The results of research into current chemistries are discussed, with a review of recent findings regarding the mechanisms of phenolic condensation and acceleration. Also, the work regarding alternate natural materials, such as carbohydrates, lignins, tannins, and proteinaceous materials, is presented. Finally, new developments in alternative adhesive technologies are reported.

  4. Optimization of geometry of elastic bodies in the vicinity of singular points on the example of an adhesive lap joint

    NASA Astrophysics Data System (ADS)

    Matveenko, V. P.; Sevodina, N. V.; Fedorov, A. Yu.

    2013-09-01

    The stress state in adhesive lap joints with various geometric shapes of spew fillet is studied. It is noted that the applied design models of the considered problem include singular points at which infinite stress values are possible if one uses the linear elasticity theory to calculate the stress state. Based on the conclusions of the solution of the geometry optimization problem in the vicinity of the singular points of elastic bodies, variants of the geometry of spew fillet, which provide the most significant decrease in the concentration of stresses in adhesive lap joints, are proposed.

  5. Evaluation of adhesives for adhering carbon/epoxy composites to various metallic substrates

    SciTech Connect

    Bonk, R.B.; Osterndorf, J.F.; Ambrosio, A.M.; Pettenger, B.L.

    1996-12-31

    The strength properties of composite matrix resins and adhesive are dependent on time, temperature, environment, and stress factors. All of these conditions combine to influence the properties of adhesives and composites in ways that are not yet fully known or quantifiable. Therefore, it is important to know the service conditions that structural adhesive bonded composite joints will encounter prior to fielding. This paper details an evaluation of five epoxy adhesives used to adhere a carbon/epoxy composite to 7075-T6 aluminum, 4340 steel and aluminum coated steel. Test results indicate that certain paste adhesives are capable of better lap-shear and peel performance than film adhesives, especially at elevated temperatures.

  6. Stress-Strain Analysis of Single-Lap Tensile Loaded Adhesive Joints

    SciTech Connect

    Raos, Pero; Kozak, Drazan; Lucic, Mirjana

    2007-05-17

    Both, experimental investigation and finite element analysis of single-lap adhesive joints subjected to tension have been done to find out an optimal overlap length. As the adherend material aluminum was considered with the two component high-strength engineering adhesive for the bonding of the layers. The thickness of the sheet metal layer was 1,95 mm, while adhesive was 0,15 mm thick. The width of all thin plates was 30 mm, but the overlap length varied as 15, 20, 30, 40 and 60 mm. Real mechanical properties of all materials in the joint have been determined experimentally. Obtained results proved that the overlap length affects directly the joint tensile strength, where an optimum value of overlap length can be defined. Finite element analysis of stress and strain fields could help to determine the moment when the crack initiates at the joint overlap end. In such a manner, complex mechanisms of failure of adhesive joints could be better understood.

  7. LAP, an alcohol acetaldehyde dehydrogenase enzyme in Listeria, promotes bacterial adhesion to enterocyte-like Caco-2 cells only in pathogenic species.

    PubMed

    Jagadeesan, Balamurugan; Koo, Ok Kyung; Kim, Kwang-Pyo; Burkholder, Kristin M; Mishra, Krishna K; Aroonnual, Amornrat; Bhunia, Arun K

    2010-09-01

    Listeria adhesion protein (LAP), an alcohol acetaldehyde dehydrogenase (lmo1634), interacts with host-cell receptor Hsp60 to promote bacterial adhesion during the intestinal phase of Listeria monocytogenes infection. The LAP homologue is present in pathogens (L. monocytogenes, L. ivanovii) and non-pathogens (L. innocua, L. welshimeri, L. seeligeri); however, its role in non-pathogens is unknown. Sequence analysis revealed 98 % amino acid similarity in LAP from all Listeria species. The N-terminus contains acetaldehyde dehydrogenase (ALDH) and the C-terminus an alcohol dehydrogenase (ADH). Recombinant LAP from L. monocytogenes, L. ivanovii, L. innocua and L. welshimeri exhibited ALDH and ADH activities, and displayed strong binding affinity (K(D) 2-31 nM) towards Hsp60. Flow cytometry, ELISA and immunoelectron microscopy revealed more surface-associated LAP in pathogens than non-pathogens. Pathogens exhibited significantly higher adhesion (P<0.05) to Caco-2 cells than non-pathogens; however, pretreatment of bacteria with Hsp60 caused 47-92 % reduction in adhesion only in pathogens. These data suggest that biochemical properties of LAP from pathogenic Listeria are similar to those of the protein from non-pathogens in many respects, such as substrate specificity, immunogenicity, and binding affinity to Hsp60. However, protein fractionation analysis of extracts from pathogenic and non-pathogenic Listeria species revealed that LAP was greatly reduced in intracellular and cell-surface protein fractions, and undetectable in the extracellular milieu of non-pathogens even though the lap transcript levels were similar for both. Furthermore, a LAP preparation from L. monocytogenes restored adhesion in a lap mutant (KB208) of L. monocytogenes but not in L. innocua, indicating possible lack of surface reassociation of LAP molecules in this bacterium. Taken together, these data suggest that LAP expression level, cell-surface localization, secretion and reassociation are

  8. Laser ablation assisted adhesive bonding of automotive structural composites

    SciTech Connect

    Boeman, R.G.; Paulauskas, F.L.; Warren, C.D.

    1999-07-03

    Laser ablation has been evaluated as a surface pretreatment prior to adhesive bonding. In prior experimental work, it was observed that when adhesively bonded, composite, single lap shear samples fail, the fracture often occurs at either the adhesive/adherend interface or in the resin rich surface layer of the composite. These two areas represent the weakest portion of the joint. Laser ablation pretreatment generates areas where the resin on the composite surface is selectively removed leaving behind exposed reinforcing fibers which are the major load bearing members of the composite. In a subsequent adhesive bonding operation, this allows portions of the fibers to be encapsulated in the adhesive while other portions of the fiber remain in the composite resin. This type of pretreatment permits fibers to bridge and reinforce the interface between adhesive and adherend. A secondary benefit is the removal of surface contaminantes by pyrolysis. Microscopic observation of laser ablated surfaces indicates a prominent, fiber rich area. Results of the mechanical evaluation indicated that the lap shear strength for laser ablated samples was significantly higher than specimens with no pretreatment or with solvent cleaning only, but were slightly lower than specimens that were mechanically roughened and cleaned with solvents prior to bonding.

  9. Rapid Adhesive Bonding of Composites

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Fox, R. L.; Sterling, S. Elmo, Jr.; Buckley, J. D.; Inge, Spencer V., Jr.; Burcher, L. G.; Wright, Robert E., Jr.

    1986-01-01

    Strong bonds created in less time and with less power than use of conventional bonding methods. Rapid adhesive bonding (RAB) technique for composites uses high-frequency induction heating toroids to quickly heat metallic susceptor impregnated with thermoplastic adhesive or sandwiched between thermoset or thermoplastic adhesive cloths or films. Susceptor steel screen or perforated steel foil.

  10. Rapid Adhesive Bonding of Composites

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Fox, R. L.; Sterling, S. Elmo, Jr.; Buckley, J. D.; Inge, Spencer V., Jr.; Burcher, L. G.; Wright, Robert E., Jr.

    1986-01-01

    Strong bonds created in less time and with less power than use of conventional bonding methods. Rapid adhesive bonding (RAB) technique for composites uses high-frequency induction heating toroids to quickly heat metallic susceptor impregnated with thermoplastic adhesive or sandwiched between thermoset or thermoplastic adhesive cloths or films. Susceptor steel screen or perforated steel foil.

  11. Comparison of peritoneal adhesion formation in bowel retraction by cotton towels versus the silicone lap pak device in a rabbit model.

    PubMed

    Liu, Brian G; Ruben, Dawn S; Renz, Wolfgang; Santillan, Antonio; Kubisen, Steven J; Harmon, John W

    2011-01-01

    Manipulation of cotton operating room towels within the abdominal cavity in open abdominal surgery has been associated with the formation of peritoneal adhesions. In a rabbit model, the use of standard cotton operating room towels is compared to the Lap Pak, a silicone bowel-packing device, to determine the potential for reducing the risk of adhesions. Thirty rabbits were randomly assigned to 3 groups. The rabbits underwent a sham surgery with incision only (n = 10), placement of operating room towels (n = 10), or placement of a Lap Pak (n = 10). After 14 days, the rabbits were sacrificed and the peritoneal cavity explored for adhesions. The number, tenacity, ease of dissection, and density of adhesions were recorded, and the adhesions quantitatively graded using a Modified Hopkins Adhesion scoring system. The operating room towel group had an average adhesion score of 2.5, and 8 (80%) rabbits developed adhesions. The sham group had an average adhesion score of 0.3 and one rabbit (10%) developed adhesions. The Lap Pak group had an average adhesion score of 0.2 and 1 rabbit (10%) developed adhesions. The frequency and severity of adhesions in the operating room towel group were significantly greater from that of the baseline sham group. There was no significant difference between the Lap Pak and sham groups. In this rabbit laparotomy model, the use of the Lap Pak to retract the bowels resulted in significantly fewer adhesions compared to cotton operating room towels. Lap Pak may be beneficial for bowel packing in general abdominal surgeries.

  12. Comparison of Peritoneal Adhesion Formation in Bowel Retraction by Cotton Towels Versus the Silicone Lap Pak Device in a Rabbit Model

    PubMed Central

    Liu, Brian G.; Ruben, Dawn S.; Renz, Wolfgang; Santillan, Antonio; Kubisen, Steven J.; Harmon, John W.

    2011-01-01

    Objective: Manipulation of cotton operating room towels within the abdominal cavity in open abdominal surgery has been associated with the formation of peritoneal adhesions. In a rabbit model, the use of standard cotton operating room towels is compared to the Lap Pak, a silicone bowel-packing device, to determine the potential for reducing the risk of adhesions. Methods: Thirty rabbits were randomly assigned to 3 groups. The rabbits underwent a sham surgery with incision only (n = 10), placement of operating room towels (n = 10), or placement of a Lap Pak (n = 10). After 14 days, the rabbits were sacrificed and the peritoneal cavity explored for adhesions. The number, tenacity, ease of dissection, and density of adhesions were recorded, and the adhesions quantitatively graded using a Modified Hopkins Adhesion scoring system. Results: The operating room towel group had an average adhesion score of 2.5, and 8 (80%) rabbits developed adhesions. The sham group had an average adhesion score of 0.3 and one rabbit (10%) developed adhesions. The Lap Pak group had an average adhesion score of 0.2 and 1 rabbit (10%) developed adhesions. The frequency and severity of adhesions in the operating room towel group were significantly greater from that of the baseline sham group. There was no significant difference between the Lap Pak and sham groups. Conclusions: In this rabbit laparotomy model, the use of the Lap Pak to retract the bowels resulted in significantly fewer adhesions compared to cotton operating room towels. Lap Pak may be beneficial for bowel packing in general abdominal surgeries. PMID:22096614

  13. Adhesive properties and adhesive joints strength of graphite/epoxy composites

    NASA Astrophysics Data System (ADS)

    Rudawska, Anna; Stančeková, Dana; Cubonova, Nadezda; Vitenko, Tetiana; Müller, Miroslav; Valášek, Petr

    2017-05-01

    The article presents the results of experimental research of the adhesive joints strength of graphite/epoxy composites and the results of the surface free energy of the composite surfaces. Two types of graphite/epoxy composites with different thickness were tested which are used to aircraft structure. The single-lap adhesive joints of epoxy composites were considered. Adhesive properties were described by surface free energy. Owens-Wendt method was used to determine surface free energy. The epoxy two-component adhesive was used to preparing the adhesive joints. Zwick/Roell 100 strength device were used to determination the shear strength of adhesive joints of epoxy composites. The strength test results showed that the highest value was obtained for adhesive joints of graphite-epoxy composite of smaller material thickness (0.48 mm). Statistical analysis of the results obtained, the study showed statistically significant differences between the values of the strength of the confidence level of 0.95. The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (0.95 confidence level). It was noted that in each of the results the dispersion component of surface free energy was much greater than polar component of surface free energy.

  14. Adhesive, elastomeric gel impregnating composition

    DOEpatents

    Shaw, David Glenn; Pollard, John Randolph; Brooks, Robert Aubrey

    2002-01-01

    An improved capacitor roll with alternating film and foil layers is impregnated with an adhesive, elastomeric gel composition. The gel composition is a blend of a plasticizer, a polyol, a maleic anhydride that reacts with the polyol to form a polyester, and a catalyst for the reaction. The impregnant composition is introduced to the film and foil layers while still in a liquid form and then pressure is applied to aid with impregnation. The impregnant composition is cured to form the adhesive, elastomeric gel. Pressure is maintained during curing.

  15. How geometric details can affect the strength of adhesive lap joints

    SciTech Connect

    Metzinger, K.E.; Guess, T.R.

    1996-12-31

    The durability of adhesively bonded joints--when utilized as blade attachments--has a significant impact on the performance of wind turbines. Accordingly, there is interest in determining how geometric details affect the strength of these joints. Finite element analyses were performed to aid in the selection of three composite-to-metal joint geometries for compressive axial testing. Both monotonic and low-cycle fatigue tests were conducted. Analysis and testing of these joints provide insight into the effects of adding extra adhesive to the end of the bond or tapering the metal adherend. The issue of whether the relative performance of different joints in monotonic tests can be used to predict the relative fatigue strength of these joints is also addressed.

  16. Predicting the geometry and location of defects in adhesive and spot-welded lap joints using steady-state thermographic techniques

    NASA Astrophysics Data System (ADS)

    Turler, Daniel; Orlando, Ernest

    1999-03-01

    Development of nondestructive evaluation (NDE) methods for spot-welded and adhesive-bonded sheet metal joints is essential for widespread use of lightweight materials and new construction techniques in automotive applications. An important objective of research in progress is development of NDE methods to identify and characterize critical flaws in welded and adhesive-bonded joints. We used steady-state heat- flow and thermographic imaging techniques to test welded and adhesive-bonded lap joints in steel and aluminum samples and in adhesive-bonded composite panels and to identify defective spot welds. The resulting surface-temperature maps or thermograms were used to detect voids and areas where the adhesive was not bonded. To better characterize defects in welds and adhesive layers, algorithms have been developed to post process temperature data, producing more accurate definition of the geometry and location of defects than in previous images. Classic heat-transfer theory was used to calculate the heat-flux equilibrium for each individual pixel on the thermograms. Convective and radiative surface heat- transfer coefficients were applied to compensate for the heat exchange between the sample and the environment. This post processing permits us to determine the locations of spot welds and the sizes of the weld nuggets in welded joints, and to clearly image voids in adhesive layers between joints. The effectiveness of the image-processing algorithms was investigated using data from laboratory experiments on test specimens with flaws of known size and location. In addition, the images of the defects produced with the new method were compared to results of two-dimensional heat transfer simulations through the same samples. The simulations were also used to determine boundary conditions for post-processing of images.

  17. Effect of adhesive thickness and surface treatment on shear strength on single lap joint Al/CFRP using adhesive of epoxy/Al fine powder

    NASA Astrophysics Data System (ADS)

    Diharjo, Kuncoro; Anwar, Miftahul; Tarigan, Roy Aries P.; Rivai, Ahmad

    2016-02-01

    The objective of this study is to investigate the effect of adhesive thickness and surface treatment on the shear strength and failure type characteristic of single lap joint (SLJ) CFRP/Al using adhesive epoxy/Al-fine-powder. The CFRP was produced by using hand layup method for 30% of woven roving carbon fiber (w/w) and the resin used was bisphenolic. The adhesive was prepared using 12.5% of aluminum fine powder (w/w) in the epoxy adhesive. The powder was mixed by using a mixing machine at 60 rpm for 6 minutes, and then it was used to join the Al plate-2024 and CFRP. The start time to pressure for the joint process was 20 minutes after the application of adhesive on the both of adherends. The variables in this research are adhesive thickness (i.e. 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm and 1 mm) and surface treatment of adherends (i.e. acetone, chromate sulphuric acid, caustic etch and tucker's reagent). Before shear testing, all specimens were post-cured at 100 °C for 15 minutes. The result shows that the SLJ has the highest shear strength for 0.4 mm of adhesive thickness. When the adhesive thickness is more than 0.4 mm (0.6-1 mm), the shear strength decreases significantly. It might be caused by the property change of adhesive from ductile to brittle. The acetone surface treatment produces the best bonding between the adhesive and adherends (CFRP and Al-plate 2024), and the highest shear strength is 9.31 MPa. The surface treatment give the humidification effect of adherend surfaces by adhesive. The failure characteristic shows that the mixed failure of light-fiber-tear-failure and cohesive-failure are occurred on the high shear strength of SLJ, and the low shear strength commonly has the adhesive-failure type.

  18. How cats lap

    NASA Astrophysics Data System (ADS)

    Stocker, Roman; Reis, Pedro; Jung, Sunghwan; Aristoff, Jeffrey

    2010-11-01

    We studied the lapping of the domestic cat (Felis catus) by combining high-speed photography with a laboratory model of lapping. We found that Felis catus laps by a subtle mechanism based on water adhesion to the dorsal side of the tongue and the creation of a liquid column, exploiting inertia to defeat gravity and pull liquid into the mouth. The competition between inertia and gravity controls the pinch-off time of the column, determining the optimal lapping frequency, f. Felis catus was found to operate near the optimum and theoretical analysis yielded a scaling, f ˜M-1/6, of lapping frequency with animal mass, M. This prediction was verified by measuring lapping frequency across felids, from ocelots to lions, suggesting that the lapping mechanism is conserved among felines.

  19. Biomimetic-inspired joining of composite with metal structures: A survey of natural joints and application to single lap joints

    NASA Astrophysics Data System (ADS)

    Avgoulas, Evangelos Ioannis; Sutcliffe, Michael P. F.

    2014-03-01

    Joining composites with metal parts leads, inevitably, to high stress concentrations because of the material property mismatch. Since joining composite to metal is required in many high performance structures, there is a need to develop a new multifunctional approach to meet this challenge. This paper uses the biomimetics approach to help develop solutions to this problem. Nature has found many ingenious ways of joining dissimilar materials and making robust attachments, alleviating potential stress concentrations. A literature survey of natural joint systems has been carried out, identifying and analysing different natural joint methods from a mechanical perspective. A taxonomy table was developed based on the different methods/functions that nature successfully uses to attach dissimilar tissues (materials). This table is used to understand common themes or approaches used in nature for different joint configurations and functionalities. One of the key characteristics that nature uses to joint dissimilar materials is a transitional zone of stiffness in the insertion site. Several biomimetic-inspired metal-to-composite (steel-to-CFRP), adhesively bonded, Single Lap Joints (SLJs) were numerically investigated using a finite element analysis. The proposed solutions offer a transitional zone of stiffness of one joint part to reduce the material stiffness mismatch at the joint. An optimisation procedure was used to identify the variation in material stiffness which minimises potential failure of the joint. It was found that the proposed biomimetic SLJs reduce the asymmetry of the stress distribution along the adhesive area.

  20. Multivariate Analysis of High Through-Put Adhesively Bonded Single Lap Joints: Experimental and Workflow Protocols

    DTIC Science & Technology

    2016-06-01

    NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) US Army Research Laboratory ATTN: RDRL-WMM-C Aberdeen Proving...and Failure Mode Analysis 12 3.2 Student and ARL Control Sample Comparisons 16 4. Conclusions and Future Work 18 5. References 19 Appendix...temperature (dry conditioning as defined by ARL-ADHES-QA-001.00 rev 1.0) ........................................................2 Fig. 3 Single-lap

  1. Fracture of composite-adhesive-composite systems

    NASA Technical Reports Server (NTRS)

    Ripling, E. J.; Santner, J. S.; Crosley, P. B.

    1984-01-01

    This program was undertaken to initiate the development of a test method for testing adhesive joints in metal-adhesive-composite systems. The uniform double cantilever beam (UDCB) and the width tapered beam (WTB) specimen geometries were evaluated for measuring Mode I fracture toughness in these systems. The WTB specimen is the preferred geometry in spite of the fact that it is more costly to machine than the UDCB specimen. The use of loading tabs attached to thin sheets of composites proved to be experimentally unsatisfactory. Consequently, a new system was developed to load thin sheets of adherends. This system allows for the direct measurement of displacement along the load line. In well made joints separation occurred between the plies rather than in the adhesive.

  2. Thermoelastic stress analysis of a pultruded composite double lap joint

    NASA Astrophysics Data System (ADS)

    Hemann, John H.; Martin, Richard E.; Mandic, Davor G.

    1999-02-01

    The use of composite materials, in particular glass/epoxy systems for structural applications has seen widespread growth. Recent examples include a bridge in Butler County, Ohio and a covered pedestrian bridge that is scheduled to be installed in Akron, Ohio. Both of these structures employ pultruded composites for the main structural members due to their high strength, light weight and the ease of manufacture into common structural shapes such as wide flanges, I-beams and box sections. The use of these shapes gives the designer the ability to use many of the same types of structural details that are common to steel design. This paper will examine the most common method of joining structural members, bolted connections. The analysis of bolted connections in composite materials has been widely reported in the literature. Analysis methods have ranged from two and three dimensional finite element analysis to more empirical methods of calculating the stress concentration factors based on experimental data. This paper will focus on the use of the thermoelastic stress analysis method to determine the stress concentration around a steel pin loaded in double shear by a pultruded glass fiber composite. Further studies were conducted to determine the time dependent material behavior on the thermoelastic stress analysis signal output. The following is a description of the theory, experimental setup, and a summary of results.

  3. Optimum design of bolted composite lap joints under mechanical and thermal loading

    NASA Astrophysics Data System (ADS)

    Kradinov, Vladimir Yurievich

    A new approach is developed for the analysis and design of mechanically fastened composite lap joints under mechanical and thermal loading. Based on the combined complex potential and variational formulation, the solution method satisfies the equilibrium equations exactly while the boundary conditions are satisfied by minimizing the total potential. This approach is capable of modeling finite laminate planform dimensions, uniform and variable laminate thickness, laminate lay-up, interaction among bolts, bolt torque, bolt flexibility, bolt size, bolt-hole clearance and interference, insert dimensions and insert material properties. Comparing to the finite element analysis, the robustness of the method does not decrease when modeling the interaction of many bolts; also, the method is more suitable for parametric study and design optimization. The Genetic Algorithm (GA), a powerful optimization technique for multiple extrema functions in multiple dimensions search spaces, is applied in conjunction with the complex potential and variational formulation to achieve optimum designs of bolted composite lap joints. The objective of the optimization is to acquire such a design that ensures the highest strength of the joint. The fitness function for the GA optimization is based on the average stress failure criterion predicting net-section, shear-out, and bearing failure modes in bolted lap joints. The criterion accounts for the stress distribution in the thickness direction at the bolt location by applying an approach utilizing a beam on an elastic foundation formulation.

  4. Debonding characteristics of adhesively bonded woven Kevlar composites

    NASA Technical Reports Server (NTRS)

    Mall, S.; Johnson, W. S.

    1988-01-01

    The fatigue damage mechanism of an adhesively bonded joint between fabric reinforced composite adherends was investigated with cracked-lap-shear specimens. Two bonded systems were studied: fabric Kevlar 49/5208 epoxy adherends bonded together with either EC 3445 or FM-300 adhesive. For each bonded system, two specimen geometries were tested. In all specimens tested, fatigue damage occurred in the form of cyclic debonding; however, the woven Kevlar specimens gave significantly slower debond growth rates and higher fracture toughness than previously found in the nonwoven adherend specimens. The surfaces for the woven adherends were not smooth; rather, they had regular crests (high spots) and troughs (low spots) due to the weave pattern. Radiographs of the specimens and examination of their failure surfaces revealed that fiber bridging occurred between the crests of the two adherends in the debonded region. The observed improvements in debond growth resistance and static fracture toughness are attributed to this bridging.

  5. Bolted Double-Lap Composite Joints Under Mechanical and Thermal Loading

    NASA Technical Reports Server (NTRS)

    Kradinov, V.; Barut, A.; Madenci, E.; Walker, Sandra P. (Technical Monitor)

    2000-01-01

    This study concerns the determination of the contact stresses and contact region around bolt holes and the bolt load distribution in single- and double-lap joints of composite laminates with arbitrarily located bolts under general mechanical loading conditions and uniform temperature change. The unknown contact stress distribution and contact region between the bolt and laminates and the interaction among the bolts require the bolt load distribution, as well as the contact stresses, to be as part of the solution. The present method is based on the complex potential theory and the variational formulation in order to account for bolt stiffness, bolt-hole clearance, and finite geometry of the composite laminates.

  6. SEM/XPS analysis of fractured adhesively bonded graphite fibre-reinforced polyimide composites

    NASA Technical Reports Server (NTRS)

    Devilbiss, T. A.; Messick, D. L.; Wightman, J. P.; Progar, D. J.

    1985-01-01

    The surfaces of the graphite fiber-reinforced polyimide composites presently pretreated prior to bonding with polyimide adhesive contained variable amounts of a fluoropolymer, as determined by X-ray photoelectron spectroscopy. Lap shear strengths were determined for unaged samples and for those aged over 500- and 1000-hour periods at 177 and 232 C. Unaged sample lap strengths, which were the highest obtained, exhibited no variation with surface pretreatment, but a significant decrease is noted with increasing aging temperature. These thermally aged samples, however, had increased surface fluorine concentration, while a minimal concentration was found in unaged samples. SEM demonstrated a progressive shift from cohesive to adhesive failure for elevated temperature-aged composites.

  7. LAP5 and LAP6 Encode Anther-Specific Proteins with Similarity to Chalcone Synthase Essential for Pollen Exine Development in Arabidopsis1[W][OA

    PubMed Central

    Dobritsa, Anna A.; Lei, Zhentian; Nishikawa, Shuh-ichi; Urbanczyk-Wochniak, Ewa; Huhman, David V.; Preuss, Daphne; Sumner, Lloyd W.

    2010-01-01

    Pollen grains of land plants have evolved remarkably strong outer walls referred to as exine that protect pollen and interact with female stigma cells. Exine is composed of sporopollenin, and while the composition and synthesis of this biopolymer are not well understood, both fatty acids and phenolics are likely components. Here, we describe mutations in the Arabidopsis (Arabidopsis thaliana) LESS ADHESIVE POLLEN (LAP5) and LAP6 that affect exine development. Mutation of either gene results in abnormal exine patterning, whereas pollen of double mutants lacked exine deposition and subsequently collapsed, causing male sterility. LAP5 and LAP6 encode anther-specific proteins with homology to chalcone synthase, a key flavonoid biosynthesis enzyme. lap5 and lap6 mutations reduced the accumulation of flavonoid precursors and flavonoids in developing anthers, suggesting a role in the synthesis of phenolic constituents of sporopollenin. Our in vitro functional analysis of LAP5 and LAP6 using 4-coumaroyl-coenzyme A yielded bis-noryangonin (a commonly reported derailment product of chalcone synthase), while similar in vitro analyses using fatty acyl-coenzyme A as the substrate yielded medium-chain alkyl pyrones. Thus, in vitro assays indicate that LAP5 and LAP6 are multifunctional enzymes and may play a role in both the synthesis of pollen fatty acids and phenolics found in exine. Finally, the genetic interaction between LAP5 and an anther gene involved in fatty acid hydroxylation (CYP703A2) demonstrated that they act synergistically in exine production. PMID:20442277

  8. Adhesives: Test Method, Group Assignment, and Categorization Guide for High-Loading-Rate Applications Preparation and Testing of Single Lap Joints (Ver. 2.2, Unlimited)

    DTIC Science & Technology

    2016-04-01

    SUBJECT TERMS single lap joint, adhesive, sample preparation, testing, database , metadata, material pedigree, ISO 16. SECURITY CLASSIFICATION OF: 17... Database : As stated within ISO/IEC 2382-17:1999, a database shall be “a collection of data organized according to a conceptual structure describing...laboratory notebook with sufficient detail to serve as trustworthy database metadata. There are 4 distinct laboratory-scale surface preparation methods

  9. Lapping slurry

    SciTech Connect

    Simandl, R.F.; Upchurch, V.S.; Leitten, M.E.

    1999-01-05

    Improved lapping slurries provide for easier and more thorough cleaning of alumina work pieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid. 1 fig.

  10. Lapping slurry

    DOEpatents

    Simandl, Ronald F.; Upchurch, Victor S.; Leitten, Michael E.

    1999-01-01

    Improved lapping slurries provide for easier and more thorough cleaning of alumina workpieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid.

  11. Experimental research and statistic analysis of polymer composite adhesive joints strength

    NASA Astrophysics Data System (ADS)

    Rudawska, Anna; Miturska, Izabela; Szabelski, Jakub; Skoczylas, Agnieszka; Droździel, Paweł; Bociąga, Elżbieta; Madleňák, Radovan; Kasperek, Dariusz

    2017-05-01

    The aim of this paper is to determine the effect of arrangement of fibreglass fabric plies in a polymer composite on adhesive joint strength. Based on the experimental results, the real effect of plies arrangement and their most favourable configuration with respect to strength is determined. The experiments were performed on 3 types of composites which had different fibre orientations. The composites had three plies of fabric. The plies arrangement in Composite I was unchanged, in Composite II the central ply had the 45° orientation, while in Composite III the outside ply (tangential to the adhesive layer) was oriented at 45°. Composite plates were first cut into smaller specimens and then adhesive-bonded in different combinations with Epidian 61/Z1/100:10 epoxy adhesive. After stabilizing, the single-lap adhesive joints were subjected to shear strength tests. It was noted that plies arrangement in composite materials affects the strength of adhesive joints made of these composites between the values of the strength of the confidence level of 0.95. The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (0.95 confidence level).

  12. LAP Catalog.

    ERIC Educational Resources Information Center

    Area Cooperative Educational Services, New Haven, CT. Educational Resources Center.

    This is a catalog of individualized learning activities packages (LAPs). A LAP is a 4" x 6" microfiche containing a maximum of 60 pages. Generally, each LAP contains two sections: (1) a section for teachers including learning objectives, suggestions for materials and activities, and test answer keys; and (2) a student section including a list of…

  13. UV-cured adhesives for carbon fiber composite applications

    NASA Astrophysics Data System (ADS)

    Lu, Hsiao-Chun

    Carbon fiber composite materials are increasingly used in automobile, marine, and aerospace industries due to their unique properties, including high strength, high stiffness and low weight. However, due to their brittle characteristic, these structures are prone to physical damage, such as a bird strike or impact damage. Once the structure is damaged, it is important to have fast and reliable temporary repair until the permanent repair or replacement can take place. In this dissertation, UV-based adhesives were used to provide a bonding strength for temporary repair. Adhesively bonded patch repair is an efficient and effective method for temporary repair. In this study, precured patches (hard patches) and dry fabric patches with laminating resins (soft patches) were performed. UV-based epoxy adhesives were applied to both patch repair systems. For precured patch repair, the bonding strengths were investigated under different surface treatments for bonding area and different adhesives thicknesses. The shear stresses of different UV exposure times and curing times were tested. Besides, the large patch repair was investigated as well. For soft patch repair, the hand wet lay-up was applied due to high viscosity of UV resins. A modified single lap shear testing (ASTM D5868) was applied to determine the shear stress. The large patches used fiber glass instead of carbon fiber to prove the possibility of repair with UV epoxy resin by hand wet lay-up process. The hand lay-up procedure was applied and assisted by vacuum pressure to eliminate the air bubbles and consolidate the patches. To enhance the bonding strength and effective soft patch repair, vacuum assisted resin transferring molding (VaRTM) is the better option. However, only low viscosity resins can be operated by VaRTM. Hence, new UV-based adhesives were formulated. The new UV-based adhesives included photoinitiator (PI), epoxy and different solvents. Solvents were used to compound the photoinitiator into epoxy

  14. Influence of interface ply orientation on fatigue damage of adhesively bonded composite joints

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Mall, S.

    1985-01-01

    An experimental study of cracked-lap-shear specimens was conducted to determine the influence of adherend stacking sequence on debond initiation and damage growth in a composite-to-composite bonded joint. Specimens consisted of quasi-isotropic graphite/epoxy adherends bonded together with either FM-300 or EC 3445 adhesives. The stacking sequence of the adherends was varied such that 0 deg, 45 deg, or 90 deg plies were present at the adherend-adhesive interfaces. Fatigue damage initiated in the adhesive layer in those specimens with 0 deg nd 45 deg interface plies. Damage initiated in the form of ply cracking in the strap adherend for the specimens with 90 deg interface plies. The fatigue-damage growth was in the form of delamination within the composite adherends for specimens with the 90 deg and 45 deg plies next to the adhesive, while debonding in the adhesive resulted for the specimens with 0 deg plies next to the adhesive. Those joints with the 0 deg and 45 deg plies next to either adhesive has essentially the same fatigue-damage-initiation stress levels. These stress levels were 13 and 71 percent higher, respectively, than those for specimens with 90 deg plies next to the EC 3445 and FM-300 adhesives.

  15. Polyimide adhesives for titanium and composite bonding

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; St. Clair, T. L.

    1978-01-01

    Approach results in synthesis of addition polyimide adhesives with exceptional high temperature capabilities that show excellent potential for bonding titanium metal, polyimide/graphite composites, and combinations of these materials. Adhesives compatible with materials used in high performance aircraft and spacecraft structures also prove highly desirable in many other applications involving similar adherents.

  16. Processable polyimide adhesive and matrix composite resin

    NASA Technical Reports Server (NTRS)

    Pratt, J. Richard (Inventor); St.clair, Terry L. (Inventor); Progar, Donald J. (Inventor)

    1990-01-01

    A high temperature polyimide composition prepared by reacting 4,4'-isophthaloyldiphthalic anhydride with metaphenylenediamine is employed to prepare matrix resins, adhesives, films, coatings, moldings, and laminates, especially those showing enhanced flow with retention of mechanical and adhesive properties. It can be used in the aerospace industry, for example, in joining metals to metals or metals to composite structures. One area of application is in the manufacture of lighter and stronger aircraft and spacecraft structures.

  17. Adhesive-composite incompatibility, part II.

    PubMed

    Carvalho, Ricardo M; Garcia, Fernanda Cristina P; e Silva, Safira M A; Castro, Fabrício L A

    2005-01-01

    Apart from some questions related to the repairability of resin composite restorations, dentists have always assumed that methacrylate-based resins are compatible with each other. For example, there is no clinically relevant problem in using a microfilled composite to laminate a Class IV restoration made with a hybrid composite, even if they are not of the same brand or manufacturer. In the context of adhesive systems, we have always believed that resin composites, regardless of their type or composition, bond well to all types of bonding agents. However, unexpected debonding of self-cured, core buildup composites that had been bonded with single-bottle adhesive systems was reported about 5 years ago. Subsequent studies demonstrated that there were, indeed, compatibility problems between simplified adhesive systems and self- or dual-cured resin composites. Apparently, when such combinations are used, reduced bond strengths and subsequent failures at the resin-adhesive interface can occur because of adverse reactions between the acidic resin monomers, an integral part of the simplified adhesive systems, and the chemicals involved in the polymerization mechanism of the self- or dual-cured composites, particularly the basic tertiary amines.

  18. Secondary bending effects in progressively damaged single-lap, single-bolt composite joints

    NASA Astrophysics Data System (ADS)

    Zhao, Libin; Xin, An; Liu, Fengrui; Zhang, Jianyu; Hu, Ning

    Static tensile experiments and progressive failure simulations of single-bolt, single- and double-lap joints were carried out to comparatively investigate secondary bending effects, which present significant eccentric-loading phenomena in single-lap joints but are almost non-existent in symmetric double-lap joints. Progressive damage models of single-lap and double-lap joints were established, from which the numerical predictions were found to be in good agreement with the experimental outcomes. Experimental macro-scope failure patterns and seven numerical micro-scope failure modes obtained from the progressive damage analyses were presented for the two types of joints. The effects of secondary bending on the mechanical degradation and failure mechanism of single-lap joints were revealed. Some characterizations of secondary bending in the joints, such as a characterized parameter on the AGARD points, joint deformations and contact states, were quantitatively traced during the total progressive damage process. All these characterizations increased the understanding of the effects of secondary bending on the failure process of a single-bolt, single-lap joint.

  19. Abernathy's Lap

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A lap in this instance is not a midriff but a tool for presision.polishing and grinding. During the Saturn V moonbooster program, Marshall Space Flight Center found a need for a better lap. The need arose from the exquisitely precise tolerances required for parts of the launch vehicle's guidance,and control system. So William J. Abernathy, a former Marshall employee, built a better lap; he invented a method for charging aluminum lap plates with diamond powder, then hard-anodizing them. The resulting lap produces a high polish on materials ranging from the softest aluminum to the hardest ceramics. It operates faster, wears longer and requires less reworking. Abernathy got NASA's permission to obtain a personal patent and he formed the one-man Abernathy Laps Co. in Huntsville, which produces a variety of laps. One of Abernathy's customers is Bell Aerospace Textron, Buffalo, which uses the laps to finish polish delicate instrument parts produced for NASA's Viking and other space programs. Says a Bell official: "Time needed (with the Abernathy lap) is a fraction of that required by conventional methods. The result is extremely accurate flatness and surface finish." Abernathy is providing laps for other manufacturing applications and for preparation of metallurgical specimens. The business is small but steady, and Abernathy plans expansion into other markets.

  20. Application of atmospheric pressure plasma in polymer and composite adhesion

    NASA Astrophysics Data System (ADS)

    Yu, Hang

    carboxyl groups, on the polymer surface after plasma treatment. The resulting strength of the bond based on lap-shear and T-peel tests correlates well with the concentration of oxygen on the polymer surface. The failure modes observed for lap-shear and T-peel tests changed from interfacial to cohesive after the plasma activation. Treating carbon-fiber-reinforced epoxy composites with the atmospheric plasma resulted in the removal of fluorinated contaminants in shallow surface layers. For contaminants that diffused deeply into the composite surface, mechanical abrasion was needed in addition to the plasma treatment to remove the impurities. While cleaning the composite, plasma also generated active oxygen groups on the substrate surface. The presence of these groups improved the adhesive bonding strength of the composite even in the presence of residual fluorine contaminants. Thus, it was speculated that plasma treatment can promote better polymer adhesion with or without fluorine contamination. Carbon nanotube sheets were also treated by the helium oxygen plasma, and the CNT surface turn from super hydrophobic to hydrophilic after a few seconds of exposure. The nanotube surface contained 15% of oxygen in the form of hydroxyl groups. Chemical coupling agents were added to the plasma activated CNT surfaces in order to crosslink the CNTs and to create bonding sites for the resin matrix. Stretched, activated and functionalized CNT was cured with dicyclopentadiene (DCPD) to produce a sheet composite with a tensile strength of 636 MPa, a modulus of 28 GPa, and a density of 1.4 g/cm 3. This may be compared to aerospace-grade aluminum with tensile strength of 572 MPa, modulus of 72 GPa, and density of 2.7 g/cm3. This work demonstrates that new high-strength composite can be produced with the use of atmospheric plasma activation and chemical crosslinking of the fiber matrix.

  1. Adhesive joint and composites modeling in SIERRA.

    SciTech Connect

    Ohashi, Yuki; Brown, Arthur A.; Hammerand, Daniel Carl; Adolf, Douglas Brian; Chambers, Robert S.; Foulk, James W., III

    2005-11-01

    Polymers and fiber-reinforced polymer matrix composites play an important role in many Defense Program applications. Recently an advanced nonlinear viscoelastic model for polymers has been developed and incorporated into ADAGIO, Sandia's SIERRA-based quasi-static analysis code. Standard linear elastic shell and continuum models for fiber-reinforced polymer-matrix composites have also been added to ADAGIO. This report details the use of these models for advanced adhesive joint and composites simulations carried out as part of an Advanced Simulation and Computing Advanced Deployment (ASC AD) project. More specifically, the thermo-mechanical response of an adhesive joint when loaded during repeated thermal cycling is simulated, the response of some composite rings under internal pressurization is calculated, and the performance of a composite container subjected to internal pressurization, thermal loading, and distributed mechanical loading is determined. Finally, general comparisons between the continuum and shell element approaches for modeling composites using ADAGIO are given.

  2. Experimental Characterization of the Properties of Double-Lap Needled and Hybrid Joints of Carbon/Epoxy Composites.

    PubMed

    Arnautov, A; Nasibullins, A; Gribniak, V; Blumbergs, I; Hauka, M

    2015-11-11

    The effect of through-thickness reinforcement by thin 1 mm steel needles (z-pins) on the static tensile strength of double-lap joints of a carbon/epoxy composite was investigated. Two types of joints-z-pinned and hybrid (including glued ones)-were considered. The joints were reinforced in the overlap region with 9, 25, or 36 z-pins. Comparing mechanical properties of the double-lap joints with the corresponding characteristics of their unpinned counterparts, the z-pins were found to be highly effective: the strength and stiffness of the pinned joints increased up to 300% and 280%, respectively. These improvements were due to a transition in the failure mechanism from debonding of the joint in the absence of z-pins to pullout or shear rupture of z-pins or to the tensile failure of laminate adherends, depending on the volume content of the pins.

  3. Strengths of composite-to-metal double-lap bolted joints

    NASA Astrophysics Data System (ADS)

    Sun, Hsien-Tang

    1998-12-01

    A three-dimensional analysis was proposed to study the through-the-thickness clamping effect on the bearing failure of double-lap bolted laminated composite joints. Experiments were first performed to characterize the material response due to bearing failure in composite bolted joints with and without lateral clamp-up supports. Composite plates made of T800H/3900-2 graphite/epoxy were selected in the tests, and various washer sizes and clamping forces were used in the study. The clamping force in the bolt was found to vary with the applied load, and may increase significantly due to a sudden through-the-thickness expansion of the laminate under the washers where bearing failure occurred. Experiments showed that the joint strength and response can be significantly affected by the bolt clamp-up, and the bolt bearing failure is a 3-D phenomenon. In order to facilitate the use of the proposed model with the ABAQUS code, an interface module 3DBOLT was developed. In order to reinforce the incompressibility condition in calculations for bearing-damaged material predicted by the model, the condition was imposed through a penalty method in the frame work of finite element analyses. The module provides a user-friendly input deck, generates automatically a joint mesh, and produces outputs and graphics for displaying the stresses, strains, and deformations of the joints and for simulating the failure progression in joints during loading. Extensive comparisons were made between the test data and model predictions. Overall, the model predicts both the failure load and response of bolted composite joints very well for various clamping forces and washer sizes. The model also predicted very well for joints failed in net-tension and shear-out modes. The predicted bolt clamp-up load as a function of the applied load agreed also very well with the data, which validates that the proposed incompressibility assumption for bearing-damaged material. Based on the model, a parametric study

  4. Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing.

    PubMed

    Villegas, Irene F; Palardy, Genevieve

    2016-02-11

    This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.

  5. The Analysis of Adhesively Bonded Advanced Composite Joints Using Joint Finite Elements

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott E.; Waas, Anthony M.

    2012-01-01

    The design and sizing of adhesively bonded joints has always been a major bottleneck in the design of composite vehicles. Dense finite element (FE) meshes are required to capture the full behavior of a joint numerically, but these dense meshes are impractical in vehicle-scale models where a course mesh is more desirable to make quick assessments and comparisons of different joint geometries. Analytical models are often helpful in sizing, but difficulties arise in coupling these models with full-vehicle FE models. Therefore, a joint FE was created which can be used within structural FE models to make quick assessments of bonded composite joints. The shape functions of the joint FE were found by solving the governing equations for a structural model for a joint. By analytically determining the shape functions of the joint FE, the complex joint behavior can be captured with very few elements. This joint FE was modified and used to consider adhesives with functionally graded material properties to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. Furthermore, proof-of-concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint. Furthermore, the capability to model non-linear adhesive constitutive behavior with large rotations was developed, and progressive failure of the adhesive was modeled by re-meshing the joint as the adhesive fails. Results predicted using the joint FE was compared with experimental results for various

  6. The analysis of adhesively bonded advanced composite joints using joint finite elements

    NASA Astrophysics Data System (ADS)

    Stapleton, Scott E.

    The design and sizing of adhesively bonded joints has always been a major bottleneck in the design of composite vehicles. Dense finite element (FE) meshes are required to capture the full behavior of a joint numerically, but these dense meshes are impractical in vehicle-scale models where a course mesh is more desirable to make quick assessments and comparisons of different joint geometries. Analytical models are often helpful in sizing, but difficulties arise in coupling these models with full-vehicle FE models. Therefore, a joint FE was created which can be used within structural FE models to make quick assessments of bonded composite joints. The shape functions of the joint FE were found by solving the governing equations for a structural model for a joint. By analytically determining the shape functions of the joint FE, the complex joint behavior can be captured with very few elements. This joint FE was modified and used to consider adhesives with functionally graded material properties to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. Furthermore, proof-of-concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint. Furthermore, the capability to model non-linear adhesive constitutive behavior with large rotations was developed, and progressive failure of the adhesive was modeled by re-meshing the joint as the adhesive fails. Results predicted using the joint FE was compared with experimental results for various

  7. Modeling the Influence of Stitching on Delamination Growth in Stitched Warp-Knit Composite Lap Joints

    NASA Technical Reports Server (NTRS)

    Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

    1999-01-01

    The effect of stitches on the failure of a single lap joint configuration was determined in a combined experimental and analytical study. The experimental study was conducted to determine debond growth under static monotonic loading. The stitches were shown to delay the initiation of the debond and provide load transfer beyond the load necessary to completely debond the stitched lap joint. The strain energy release rates at the debond front were calculated using a finite element-based technique. Models of the unstitched configuration showed significant values of modes I and II across the width of the joint and showed that mode III is zero at the centerline but increases near the free edge. Models of the stitched configuration showed that the stitches effectively reduced mode I to zero, but had less of an effect on modes II and III.

  8. Mixed-mode cyclic debonding of adhesively bonded composite joints. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Rezaizadeh, M. A.; Mall, S.

    1985-01-01

    A combined experimental-analytical investigation to characterize the cyclic failure mechanism of a simple composite-to-composite bonded joint is conducted. The cracked lap shear (CLS) specimens of graphite/epoxy adherend bonded with EC-3445 adhesive are tested under combined mode 1 and 2 loading. In all specimens tested, fatigue failure occurs in the form of cyclic debonding. The cyclic debond growth rates are measured. The finite element analysis is employed to compute the mode 1, mode 2, and total strain energy release rates (i.e., GI, GII, and GT). A wide range of mixed-mode loading, i.e., GI/GII ranging from 0.03 to 0.38, is obtained. The total strain energy release rate, G sub T, appeared to be the driving parameter for cyclic debonding in the tested composite bonded system.

  9. PLASMA POLYMER FILMS AS ADHESION PROMOTING PRIMERS FOR ALUMINUM. PART II: STRENGTH AND DURABILITY OF LAP JOINTS

    EPA Science Inventory

    Plasma polymerized hexamethyldisiloxane (HMDSO) films (~800 A in thickness) were deposited onto 6111-T4 aluminum substrates in radio frequency and microwave powered reactors and used as primers for structural adhesive bonding. Processing variables such as substrate pre-treatment,...

  10. PLASMA POLYMER FILMS AS ADHESION PROMOTING PRIMERS FOR ALUMINUM. PART II: STRENGTH AND DURABILITY OF LAP JOINTS

    EPA Science Inventory

    Plasma polymerized hexamethyldisiloxane (HMDSO) films (~800 A in thickness) were deposited onto 6111-T4 aluminum substrates in radio frequency and microwave powered reactors and used as primers for structural adhesive bonding. Processing variables such as substrate pre-treatment,...

  11. The effects of molecular weight on the single lap shear creep and constant strain rate behavior of thermoplastic polyimidesulfone adhesive

    NASA Technical Reports Server (NTRS)

    Dembosky, Stanley K.; Sancaktar, Erol

    1985-01-01

    The bonded shear creep and constant strain rate behaviors of zero, one, and three percent endcapped thermoplastic polyimidesulfone adhesive were examined at room and elevated temperatures. Endcapping was accomplished by the addition of phthalic anhydrides. The primary objective was to determine the effects of molecular weight on the mechanical properties of the adhesive. Viscoelastic and nonlinear elastic constitutive equations were utilized to model the adhesive. Ludwik's and Crochet's relations were used to describe the experimental failure data. The effects of molecular weight changes on the above mentioned mechanical behavior were assessed. The viscoelastic Chase-Goldsmith and elastic nonlinear relations gave a good fit to the experimental stress strain behavior. Crochet's relations based on Maxwell and Chase-Goldsmith models were fit to delayed failure data. Ludwik's equations revealed negligible rate dependence. Ultimate stress levels and the safe levels for creep stresses were found to decrease as molecular weight was reduced.

  12. Integrating electrostatic adhesion to composite structures

    NASA Astrophysics Data System (ADS)

    Heath, Callum J. C.; Bond, Ian P.; Potter, Kevin D.

    2015-04-01

    Additional functionality within load bearing components holds potential for adding value to a structure, design or product. We consider the adaptation of an established technology, electrostatic adhesion or electroadhesion, for application in glass fibre reinforced polymer (GFRP) composite materials. Electroadhesion uses high potential difference (~2-3 kV) between co-planar electrodes to generate temporary holding forces to both electrically conductive and nonconductive contact surfaces. Using a combination of established fabrication techniques, electroadhesive elements are co-cured within a composite host structure during manufacture. This provides an almost symbiotic relationship between the electroadhesive and the composite structure, with the electroadhesive providing an additional functionality, whilst the epoxy matrix material of the composite acts as a dielectric for the high voltage electrodes of the device. Silicone rubber coated devices have been shown to offer high shear load (85kPa) capability for GFRP components held together using this technique. Through careful control of the connection interface, we consider the incorporation of these devices within complete composite structures for additional functionality. The ability to vary the internal connectivity of structural elements could allow for incremental changes in connectivity between discrete sub-structures, potentially introducing variable stiffness to the global structure.

  13. Influence of Dissimilar Adherends on the Stress Distribution in Adhesively Bonded Composite Joints Subjected to Impact Loadings

    NASA Astrophysics Data System (ADS)

    Hazimeh, R.; Challita, G.; Khalil, K.; Othman, R.

    2015-01-01

    The influence of nonsymmetric rotation of laminates on the shear and peel stresses in the adhesive layer of adhesively bonded double-lap composite joints (DLJ) subjected to in-plane impact compressive loadings is investigated by using a three-dimensional finite-element analysis. The compressive in-plane impact on DLJ is simulated using the direct Hopkinson bar system, and the specimen is impacted by an incident bar. It is found that the rotation of any adherend from the 0° orientation leads to a decrease in the average shear stress in the adhesive layer, but the maximum peel stress is affected only by the longitudinal stiffness of the outer adherend and decreases when this stiffness diminishes.

  14. Shear Pressed Aligned Carbon Nanotubes and their use as Composite and Adhesive Interlayers

    NASA Astrophysics Data System (ADS)

    Stahl, James Joseph, III

    fiber nonwoven. A SPS falls into a short fiber nonwoven and is studied as a non-infused, infused, and infused functionalized interleaf in unidirectional carbon fiber composites for GIC improvement over non-interleaved samples. As with traditional interleaving studies it is possible to decrease delamination fracture toughness as well as increase, and the reasons for either are not always clear. While the SPS interleaves are promising to resist delamination, the scatter of the results make it an unreliable method of improvement. While these studies showed significant variability in effect of the interleaf, given the correct morphology of the SPS and precise measurement during the DCB testing it is possible to improve fracture toughness significantly with all SPS interleaves. A unique fabrication method is used to incorporate the SPS interleaves into lap joint and double strap joint geometries using a prepreg lay-up fabrication similar to forming the DCB specimens. This allowed study of the use of the SPS interleaf as an adhesive layer without the need to develop a SPS adhesive film that would not fail prematurely due to poor adhesion to cured composite panels. Results showed that improvement in GIC is not directly translated into improvement in joint strength. Lap joints showed a higher relationship between GIC than double strap joints likely due to the specimen geometry that results in the adhesive layer of lap joints failing in tension rather than shear.

  15. Environmental Aging of Scotch-Weld(TradeMark) AF-555M Structural Adhesive in Composite to Composite Bonds

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Miner, Gilda A.; Lowther, Sharon E.; Connell, John W.; Baughman, James M.

    2010-01-01

    Fiber reinforced resin matrix composites have found increased usage in recent years. Due to the lack of service history of these relatively new material systems, their long-term aging performance is not well established. In this study, adhesive bonds were prepared by the secondary bonding of Scotch-Weld(TradeMark) AF-555M between pre-cured adherends comprised of T800H/3900-2 uni-directional laminate. The adherends were co-cured with wet peel-ply for surface preparation. Each bond-line of single-lap-shear (SLS) specimen was measured to determine thickness and inspected visually for voids. A three-year environmental aging plan for the SLS specimens at 82 C and 85% relative humidity was initiated. SLS strengths were measured for both controls and aged specimens at room temperature and 82 C. The aging results of strength retention and failure modes to date are reported.

  16. Influence of composition on the adhesive strength and initial viscosity of denture adhesives.

    PubMed

    Han, Jian-min; Hong, Guang; Hayashida, Kentaro; Maeda, Takeshi; Murata, Hiroshi; Sasaki, Keiichi

    2014-01-01

    To investigate the effect of composition on the initial viscosity and adhesive strength between denture adhesives and the denture base. Two types of water-soluble polymers (methoxy ethylene maleic anhydride copolymer [PVM-MA] and sodium carboxymethyl cellulose [CMC]) were used. Samples were divided into three groups. Group 1 contained only PVM-MA; Group 2 contained only CMC; and Group 3 contained PVM-MA and CMC. The initial viscosity and adhesive strength were measured. For Group 1, the initial viscosity increased significantly as PVM-MA content increased. The adhesive strength of Group 1 lasted longer than Group 2. The adhesive strength of Group 3 varied greatly. The ratio of CMC and PVM-MA has a significant effect on the initial viscosity and adhesive strength of denture adhesives. Our results suggest that it is possible to improve the durability of a denture adhesive by combining different water-soluble polymers.

  17. Investigation of modified cottonseed protein adhesives for wood composites

    USDA-ARS?s Scientific Manuscript database

    Several modified cottonseed protein isolates were studied and compared to corresponding soy protein isolates for their adhesive properties when bonded to wood composites. Modifications included treatments with alkali, guanidine hydrochloride, sodium dodecyl sulfate (SDS), and urea. Wood composites...

  18. Static Strength of Adhesively-bonded Woven Fabric Kenaf Composite Plates

    NASA Astrophysics Data System (ADS)

    Hilton, Ahmad; Lee, Sim Yee; Supar, Khairi

    2017-06-01

    Natural fibers are potentially used as reinforcing materials and combined with epoxy resin as matrix system to form a superior specific strength (or stiffness) materials known as composite materials. The advantages of implementing natural fibers such as kenaf fibers are renewable, less hazardous during fabrication and handling process; and relatively cheap compared to synthetic fibers. The aim of current work is to conduct a parametric study on static strength of adhesively bonded woven fabric kenaf composite plates. Fabrication of composite panels were conducted using hand lay-up techniques, with variation of stacking sequence, over-lap length, joint types and lay-up types as identified in testing series. Quasi-static testing was carried out using mechanical testing following code of practice. Load-displacement profiles were analyzed to study its structural response prior to ultimate failures. It was found that cross-ply lay-up demonstrates better static strength compared to quasi-isotropic lay-up counterparts due to larger volume of 0° plies exhibited in cross-ply lay-up. Consequently, larger overlap length gives better joining strength, as expected, however this promotes to weight penalty in the joining structure. Most samples showed failures within adhesive region known as cohesive failure modes, however, few sample demonstrated interface failure. Good correlations of parametric study were found and discussed in the respective section.

  19. Universal adhesive (glue composition) for electrical porcelain products

    SciTech Connect

    Khristoforov, K.K.; Belen'kaya, E.S.; Omel'chenko, Y.A.; Vinogradova, T.K.

    1986-05-01

    The aim of this work is to develop an adhesive for porcelain insulators that exhibits high physicomechanical properties and increased resistance to the simultaneous action of heat and moisture. One method of solving this problem is to introduce special additives possessing hydrophobic (waterrepelling) properties into the adhesive composition during the process of its preparation. The adhesive based on the ED-20 epoxy resin and TEA hardened with 5 parts of AF-2 additive possesses higher resistance to the action of heat and moisture as compared to the adhesive used at the present time for assembling insulators. The improved and stable physiomechanical properties of the developed adhesive permit its use in any climactic conditions.

  20. Evaluation of composite adhesive bonds using digital image correlation

    NASA Astrophysics Data System (ADS)

    Shrestha, Shashi Shekhar

    Advanced composite materials are widely used for many structural applications in the aerospace/aircraft industries today. Joining of composite structures using adhesive bonding offers several advantages over traditional fastening methods. However, this technique is not yet employed for fastening the primary structures of aircrafts or space vehicles. There are several reasons for this: There are not any reliable non-destructive evaluation (NDE) methods that can quantify the strength of the bonds, and there are no certifications of quality assurance for inspecting the bond quality. Therefore, there is a significant need for an effective, reliable, easy to use NDE method for the analysis of composite adhesive joints. This research aimed to investigate an adhesively bonded composite-aluminum joints of variable bond strength using digital image correlation (DIC). There are many future possibilities in continuing this research work. As the application of composite materials and adhesive bond are increasing rapidly, the reliability of the composite structures using adhesive bond should quantified. Hence a lot of similar research using various adhesive bonds and materials can be conducted for characterizing the behavior of adhesive bond. The results obtained from this research will set the foundation for the development of ultrasonic DIC as a nondestructive approach for the evaluation of adhesive bond line.

  1. Fiber-matrix interfacial adhesion in natural fiber composites

    NASA Astrophysics Data System (ADS)

    Tran, L. Q. N.; Yuan, X. W.; Bhattacharyya, D.; Fuentes, C.; van Vuure, A. W.; Verpoest, I.

    2015-04-01

    The interface between natural fibers and thermoplastic matrices is studied, in which fiber-matrix wetting analysis and interfacial adhesion are investigated to obtain a systematic understanding of the interface. In wetting analysis, the surface energies of the fibers and the matrices are estimated using their contact angles in test liquids. Work of adhesion is calculated for each composite system. For the interface tests, transverse three point bending tests (3PBT) on unidirectional (UD) composites are performed to measure interfacial strength. X-ray photoelectron spectroscopy (XPS) characterization on the fibers is also carried out to obtain more information about the surface chemistry of the fibers. UD composites are examined to explore the correlation between the fiber-matrix interface and the final properties of the composites. The results suggest that the higher interfacial adhesion of the treated fiber composites compared to untreated fiber composites can be attributed to higher fiber-matrix physico-chemical interaction corresponding with the work of adhesion.

  2. [Bonding compatibility between adhesive systems and composite resins].

    PubMed

    Giachetti, L; Scaminaci Russo, D; Landi, D

    2003-04-01

    The purpose of the present study was to analyse bonding compatibility between photo- and self-polymerising composite resins ad two-step total-etch (one component) adhesive systems with a different activation method. Thirty healthy extracted molars were cut transversally to obtain sixty flat dentin surfaces. The acid conditioned surfaces were bonded with Scotchbond 1 (3M), Excite (Vivadent) or Excite DSC (Vivadent). A cylinder of composite resin (3 mm diameter and 4 mm height) was constructed on each adhesive layer using photopolymerised Tetric Ceram (Vivadend) and dual Luxacore (DMG) but activated only chemically. The samples were subjected to the shear bond test. The fracture surfaces obtained were classified by type and site in the stereomicroscope. Twelve samples representing each group were further prepared for the SEM. The data obtained from the test, the microscopic investigation and statistical analysis (ANOVA and Bonferroni) seem to confirm the presence of a reduced bonding compatibility between one-component adhesive systems and self-polymerising composites. This incompatibility is evident for the adhesive Scotchbond 1 and limited for Excite, while it seems to be overcome by Excite DSC which appears to bond well with both Tetric Ceram and Luxacore. Adhesive-composite incompatibility seems to depend on the activation method of the composite as well as on that of the adhesive system. The chemical compatibility bet-ween these two materials is influenced not only by the chemical composition of the adhesive, but also by that of the composite.

  3. Functionally Graded Adhesives for Composite Joints

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott E.; Waas, Anthony M.; Arnold, Steven M.

    2012-01-01

    Adhesives with functionally graded material properties are being considered for use in adhesively bonded joints to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. An enhanced joint finite element, which uses an analytical formulation to obtain exact shape functions, is used to model the joint. Furthermore, proof of concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint.

  4. Tubular lap joints for wind turbine applications

    SciTech Connect

    Reedy, E.D. Jr.; Guess, T.R.

    1990-01-01

    A combined analytical/experimental study of the strength of thick- walled, adhesively bonded PMMA-to-aluminum and E-glass/epoxy composite-to-aluminum tubular lap joints under axial load has been conducted. Test results include strength and failure mode data. Moreover, strain gages placed along the length of the outer tubular adherend characterize load transfer from one adherend to the other. The strain gage data indicate that load transfer is nonuniform and that the relatively compliant PMMA has the shorter load transfer length. Strains determined by a finite element analysis of the tested joints are in excellent agreement with those measured. Calculated bond stresses are highest in the region of observed failure, and extensive bond yielding is predicted in the E- glass/epoxy composite-to-aluminum joint prior to joint failure. 4 refs., 13 figs., 1 tab.

  5. A comprehensive assessment of adhesively bonded joints between sandwich composite beams

    NASA Astrophysics Data System (ADS)

    Shahin, Khaled Omar

    Assessment of adhesively bonded joints between sandwich composite beams are presented in this thesis in three parts, each is concerned with a distinct aspect of the joint behaviour. In physical order, these include the deformations of the entire joint assembly, the state of stress in the joint overlap region, and the strain energy release at the crack-tip at the end of the overlap. Analytical models developed in this thesis, however, are not limited in their application to adhesive joint between sandwich beams. In each part of this thesis, the integrity of the proposed analytical models are tested against geometrically non-linear finite element models. In this first part of this thesis, an analytical asymptotic model is presented for the analysis of balanced and unbalanced adhesively bonded joints. The model takes advantage of the asymptotic nature of the adhesive stress functions by eliminating exponentially small terms. Analysis of balanced and unbalanced adhesive joints is greatly simplified with negligible loss in accuracy. Accurate closed-form solutions for both adhesive peel and shear stresses are presented, providing an efficient analysis and design tool and a significant contribution to the literature on unbalanced adhesively bonded joints. In the second part, the asymptotic model is extended to the analysis of strain energy release rates in adhesively bonded joints, using the crack closure concept. Closed-form expressions are presented for various joint types. The shear force and adhesive layer effects are included in the analysis, thus improving on currently available works in the literature. In joints with a long crack and a thin adhesive layer, the asymptotic model is shown to be in good agreement with classical beam theory models. In the third part, deformations in adhesively bonded joints between sandwich beams are studied. Adherends are modeled as cylindrically bent plates on elastic foundations and the overlap section is treated as a single

  6. Polyimide adhesive bonding

    NASA Technical Reports Server (NTRS)

    Progar, D.

    1979-01-01

    Adhesive systems which could be used to bond composite-to-composite, composite-to-titanium, and honeycomb sandwich structures with operational capability at 589K for a minimum of 125 hours were evaluated. Evaluations were based on mechanical property tests such as lap shear and flatwise tensile and on processability. Quasi-isotropic Celion 6000/PMR-15 composite adherend was used to construct lap shear and flatwise tensile specimens. Hexcel's HRH-327-3/16-6.0 glass polyimide honeycomb core was also utilized in the flatwise tensile specimens. Numerous processing variations were also studied that led to selected cure cycles for each adhesive. Shear specimens having either 12 mm or 75 mm overlaps were used to determine the effect of bond size on processability and lap shear properties. The data indicate that processing of FM-34, FM-34B-18, LARC-13 and NRO56X can be achieved using a cure compatible with the composite adherend. No significant differences in mechanical properties were observed among the three adhesive systems and all three are suitable candidates for 589K/125 hour service.

  7. Rapid adhesive bonding of advanced composites and titanium

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryart, J. R.; Hodgest, W. T.

    1985-01-01

    Rapid adhesive bonding (RAB) concepts utilize a toroid induction technique to heat the adhesive bond line directly. This technique was used to bond titanium overlap shear specimens with 3 advanced thermoplastic adhesives and APC-2 (graphite/PEEK) composites with PEEK film. Bond strengths equivalent to standard heated-platen press bonds were produced with large reductions in process time. RAB produced very strong bonds in APC-2 adherend specimens; the APC-2 adherends were highly resistant to delamination. Thermal cycling did not significantly affect the shear strengths of RAB titanium bonds with polyimide adhesives. A simple ultrasonic non-destructive evaluation process was found promising for evaluating bond quality.

  8. Important compositional characteristics in the clinical use of adhesive systems.

    PubMed

    Miyazaki, Masashi; Tsujimoto, Akimasa; Tsubota, Keishi; Takamizawa, Toshiki; Kurokawa, Hiroyasu; Platt, Jeffrey A

    2014-03-01

    Improvements in dentin bonding systems have influenced modern restorative dentistry. The desire for minimal invasiveness has resulted in more-conservative cavity design, which basically relies on the effectiveness of current dentin bonding systems. Interaction of adhesives with enamel and dentin is based on two systems, commonly described as etch-and-rinse and self-etch. Priming and bonding agents can be separate or combined, resulting in two- or three-step systems for etch-and-rinse adhesives and one- or two-step systems for self-etch adhesives. Self-etch systems use acidic functional monomers that simultaneously demineralize and impregnate tooth structures. Etch-and-rinse and self-etch systems have advantages and disadvantages, which are primarily related to the simplified bonding procedures required under clinical conditions. Knowledge of the composition, characteristics, and mechanisms of adhesion for each adhesive system is critical in selecting the ideal adhesive materials for clinical use.

  9. LARC-13 adhesive development

    NASA Technical Reports Server (NTRS)

    Hill, S. G.; Sheppard, C. H.; Johnson, J. C.

    1980-01-01

    A LARC-13 type adhesive system was developed and property data obtained that demonstrated improved thermomechanical properties superior to base LARC-13 adhesive. An improved adhesive for 589 K (600 F) use was developed by physical or chemical modification of LARC-13. The adhesive was optimized for titanium and composite bonding, and a compatible surface preparation for titanium and composite substrates was identified. The data obtained with the improved adhesive system indicated it would meet the 589 K (600 F) properties desired for application on space shuttle components. Average titanium lap shear data were: (1) 21.1 MPa (3355 psi) at RT, (2) 13.0 MPa (1881 psi) at 600 F, and (3) 16.4 MPa (2335) after aging 125 hours at 600 F and tested at 600 F.

  10. Surface modifications of nylon/carbon fiber composite for improving joint adhesion

    SciTech Connect

    Wu, R.; Liao, S.L.; Tong, T.S.; Young, J.T.

    1996-12-31

    Various methods were used to modify the nylon/carbon fiber composite surfaces, including grit blasting, flame and plasma pretreatments. The surfaces of nylon composites after pretreatments were characterized by contact angle measurements, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). XPS results show that several functional groups were formed after plasma and flame pretreatments. The scanning electron microscope (SEM) photographs suggest that the blasting pretreatment increased the surface roughness of nylon composites. All these surface pretreatments dramatically increased the lap shear strength if proper operation conditions were used. The reasons for the increase of lap shear strength were explained.

  11. Improved Materials for Composites and Adhesives.

    DTIC Science & Technology

    1981-12-01

    Bonding Aging Aluminum Alloys Adherends; Sputter Profile Analysis Shear Strength Adsorption Photoelastic Surface Area Surface Analysis Auger Electron ...Anodization of 2024-T3 Aluminum 108 (1) Introduction 108 (2) Experimental 110 (3) Results 112 (a) Scanning electron microscope 112 (b) Auger sputter profile...ADHESIVE BONDED JOINT 172 V TRAVELING WAVE TUBES 174 1. CHARACTERIZATION OF CATHODES 174 A. Evaporation Rates 177 B. Scanning Low Energy Electron Probe

  12. Adhesive-Bonded Composite Joint Analysis with Delaminated Surface Ply Using Strain-Energy Release Rate

    NASA Technical Reports Server (NTRS)

    Chadegani, Alireza; Yang, Chihdar; Smeltzer, Stanley S. III

    2012-01-01

    This paper presents an analytical model to determine the strain energy release rate due to an interlaminar crack of the surface ply in adhesively bonded composite joints subjected to axial tension. Single-lap shear-joint standard test specimen geometry with thick bondline is followed for model development. The field equations are formulated by using the first-order shear-deformation theory in laminated plates together with kinematics relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. The system of second-order differential equations is solved to using the symbolic computation tool Maple 9.52 to provide displacements fields. The equivalent forces at the tip of the prescribed interlaminar crack are obtained based on interlaminar stress distributions. The strain energy release rate of the crack is then determined by using the crack closure method. Finite element analyses using the J integral as well as the crack closure method are performed to verify the developed analytical model. It has been shown that the results using the analytical method correlate well with the results from the finite element analyses. An attempt is made to predict the failure loads of the joints based on limited test data from the literature. The effectiveness of the inclusion of bondline thickness is justified when compared with the results obtained from the previous model in which a thin bondline and uniform adhesive stresses through the bondline thickness are assumed.

  13. Adhesive-Bonded Composite Joint Analysis with Delaminated Surface Ply Using Strain-Energy Release Rate

    NASA Technical Reports Server (NTRS)

    Chadegani, Alireza; Yang, Chihdar; Smeltzer, Stanley S. III

    2012-01-01

    This paper presents an analytical model to determine the strain energy release rate due to an interlaminar crack of the surface ply in adhesively bonded composite joints subjected to axial tension. Single-lap shear-joint standard test specimen geometry with thick bondline is followed for model development. The field equations are formulated by using the first-order shear-deformation theory in laminated plates together with kinematics relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. The system of second-order differential equations is solved to using the symbolic computation tool Maple 9.52 to provide displacements fields. The equivalent forces at the tip of the prescribed interlaminar crack are obtained based on interlaminar stress distributions. The strain energy release rate of the crack is then determined by using the crack closure method. Finite element analyses using the J integral as well as the crack closure method are performed to verify the developed analytical model. It has been shown that the results using the analytical method correlate well with the results from the finite element analyses. An attempt is made to predict the failure loads of the joints based on limited test data from the literature. The effectiveness of the inclusion of bondline thickness is justified when compared with the results obtained from the previous model in which a thin bondline and uniform adhesive stresses through the bondline thickness are assumed.

  14. Critical appraisal: adhesive-composite incompatibility, part I.

    PubMed

    Carvalho, Ricardo M; Garcia, Fernanda Cristina P; E Silva, Safira M A; Castro, Fabrício L A

    2005-01-01

    Apart from some questions related to the repairability of resin composite restorations, dentists have always assumed that methacrylate-based resins are compatible with each other. For example, there is no clinically relevant problem in using a microfilled composite to laminate a Class IV restoration made with a hybrid composite, even if they are not of the same brand or manufacturer. In the context of adhesive systems, we have always believed that resin composites, regardless of their type or composition, bond well to all types of bonding agents. However, unexpected debonding of self-cured, core buildup composites that had been bonded with single-bottle adhesive systems was reported about 5 years ago. Subsequent studies demonstrated that there were, indeed, compatibility problems between simplified adhesive systems and self- or dual-cured resin composites. Apparently, when such combinations are used, reduced bond strengths and subsequent failures at the resin-adhesive interface can occur because of adverse reactions between the acidic resin monomers, an integral part of the simplified adhesive systems, and the chemicals involved in the polymerization mechanism of the self- or dual-cured composites, particularly the basic tertiary amines. At least one research group has expanded the information on this issue by further investigating the mechanisms involved in this phenomenon. This group demonstrated that not only adverse chemical reactions but also the permeability of such simplified systems contribute to the compromised bonding. This issue has profound clinical implications in view of the wide use of self- and dual-cured composites as core buildup materials and in the bonding of indirect restorations and endodontic posts. Some of the most representative studies of this group are described in this Critical Appraisal. Part II will appear in the next issue of the Journal.

  15. Adhesive and Composite Properties of a New Phenylethynyl Terminated Imide

    NASA Technical Reports Server (NTRS)

    Thompson, C. M.; Connell, J. W.; Hergenrother, P. M.

    2002-01-01

    A relatively new phenylethynyl terminated imide oligomer (PETI) from the reaction of 2,3,',4'- biphenyltetracarboxylic dianhydride, 4,4'-oxydianiline and endcapped with 4- phenylethynylphthalic anhydride at a calculated number average molecular weight of 5000 g/mole was evaluated as an adhesive and composite matrix. The asymmetric dianhydride imparts a low melt viscosity to the oligomer and a high glass transition temperature to the cured resin. Preliminary adhesive work with titanium (6Al-4V) adherend gave good room temperature (RT) tensile shear strengths and excellent retention of RT strength at 260 C. Preliminary composite work using unsized IM7 carbon fiber provided moderate to high mechanical properties. The chemistry, mechanical, and physical properties of the new PETI in neat resin, adhesive and composite form are presented.

  16. Characterization of adhesive from oysters: A structural and compositional study

    NASA Astrophysics Data System (ADS)

    Alberts, Erik

    The inability for man-made adhesives to set in wet or humid environments is an ongoing challenging the design of biomedical and marine adhesive materials. However, we see that nature has already overcome this challenge. Mussels, barnacles, oysters and sandcastle worms all have unique mechanisms by which they attach themselves to surfaces. By understanding what evolution has already spent millions of years perfecting, we can design novel adhesive materials inspired by nature's elegant designs. The well-studied mussel is currently the standard for design of marine inspired biomimetic polymers. In the work presented here, we aim to provide new insights into the adhesive produced by the eastern oyster, Crassostrea virginica. Unlike the mussel, which produces thread-like plaques comprised of DOPA containing-protein, the oyster secretes an organic-inorganic hybrid adhesive as it settles and grows onto a surface. This form of adhesion renders the oyster to be permanently fixed in place. Over time, hundreds of thousands of oyster grow and agglomerate to form extensive reef structures. These reefs are not only essential to survival of the oyster, but are also vital to intertidal ecosystems. While the shell of the oyster has been extensively studied, curiously, only a few conflicting insights have been made into the nature of the adhesive and contact zone between shell and substrate, and even lesfs information has been ascertained on organic and inorganic composition. In this work, we provide microscopy and histochemical studies to characterize the structure and composition of the adhesive, using oyster in the adult and juvenile stages of life. Preliminary work on extracting and characterizing organic components through collaborative help with solid-state NMR (SSNMR) and proteomics are also detailed here. We aim to provide a full, comprehensive characterization of oyster adhesive so that in the future, we may apply what we learn to the design of new materials.

  17. Adhesive Bonding Characterization of Composite Joints for Cryogenic Usage

    NASA Technical Reports Server (NTRS)

    Graf, Neil A.; Schieleit, Gregory F.; Biggs, Robert

    2000-01-01

    The development of polymer composite cryogenic tanks is a critical step in creating the next generation of launch vehicles. Future reusable launch vehicles need to minimize the gross liftoff weight (GLOW). This weight reduction is possible due to the large reduction in weight that composite materials can provide over current aluminum technology. In addition to composite technology, adhesively bonded joints potentially have several benefits over mechanically fastened joints, such as weight savings and cryogenic fluid containment. Adhesively bonded joints may be used in several areas of these cryogenic tanks, such as in lobe-to-lobe joints (in a multi-lobe concept), skirt-to-tank joint, strut-to-tank joint, and for attaching stringers and ring frames. The bonds, and the tanks themselves, must be able to withstand liquid cryogenic fuel temperatures that they contain. However, the use of adhesively bonded composite joints at liquid oxygen and hydrogen temperatures is largely unknown and must be characterized. Lockheed Martin Space Systems Company, Michoud Operations performed coupon-level tests to determine effects of material selection, cure process parameters, substrate surface preparation, and other factors on the strength of these composite joints at cryogenic temperatures. This led to the selection of a material and process that would be suitable for a cryogenic tank. KEY WORDS: Composites, Adhesive Bonding, Cryogenics

  18. Marginal adaptation of composite resins under two adhesive techniques.

    PubMed

    Dačić, Stefan; Veselinović, Aleksandar M; Mitić, Aleksandar; Nikolić, Marija; Cenić, Milica; Dačić-Simonović, Dragica

    2016-11-01

    In the present research, different adhesive techniques were used to set up fillings with composite resins. After the application of etch and rinse or self etch adhesive technique, marginal adaptation of composite fillings was estimated by the length of margins without gaps, and by the microretention of resin in enamel and dentin. The study material consisted of 40 extracted teeth. Twenty Class V cavities were treated with 35% phosphorous acid and restored after rinsing by Adper Single Bond 2 and Filtek Ultimate-ASB/FU 3M ESPE composite system. The remaining 20 cavities were restored by Adper Easy One-AEO/FU 3M ESPE composite system. Marginal adaptation of composite fillings was examined using a scanning electron microscope (SEM). The etch and rinse adhesive technique showed a significantly higher percentage of margin length without gaps (in enamel: 92.5%, in dentin: 57.3%), compared with the self-etch technique with lower percentage of margin length without gaps, in enamel 70.4% (p < .001), and in dentin-22.6% (p < .05). In the first technique, microretention was composed of adhesive and hybrid layers as well as resin tugs in interprismatic spaces of enamel, while the dentin microretention was composed of adhesive and hybrid layers with resin tugs in dentin canals. In the second technique, resin tugs were rarely seen and a microgap was dominant along the border of restoration margins. The SEM analysis showed a better marginal adaptation of composite resin to enamel and dentin with better microretention when the etch and rinse adhesive procedure was applied.

  19. Three-Dimensional Adhesion Map Based on Surface and Interfacial Cutting Analysis System for Predicting Adhesion Properties of Composite Electrodes.

    PubMed

    Kim, Kyuman; Byun, Seoungwoo; Cho, Inseong; Ryou, Myung-Hyun; Lee, Yong Min

    2016-09-14

    Using a surface and interfacial cutting analysis system (SAICAS) that can measure the adhesion strength of a composite electrode at a specific depth from the surface, we can subdivide the adhesion strength of a composite electrode into two classes: (1) the adhesion strength between the Al current collector and the cathode composite electrode (FAl-Ca) and (2) the adhesion strength measured at the mid-depth of the cathode composite electrode (Fmid). Both adhesion strengths, FAl-Ca and Fmid, increase with increasing electrode density and loading level. From the SAICAS measurement, we obtain a mathematical equation that governs the adhesion strength of the composite electrodes. This equation revealed a maximum accuracy of 97.2% and 96.1% for FAl-Ca and Fmid, respectively, for four randomly chosen composite electrodes varying in electrode density and loading level.

  20. Improved Materials for Composite and Adhesive Joints.

    DTIC Science & Technology

    1984-07-01

    Mechanical Testing 1 b. Composites Fabricated 2 2. RELATIONSHIP BETWEEN NEAT RESIN AND IN SITU COMPOSITE PROPERTIES 5 3. MATERIAL DEVELOPMENT 6 a...inspection revealed large variations in thickness across the width of the tape. This problem is serious in that the resin has a very high melt viscosity...and thus unfor- giving in correcting variations during composite processing. There is little or no resin loss during processing. The PEEK resin in

  1. Adhesion characterization and defect sizing of sandwich honeycomb composites.

    PubMed

    Ndiaye, Elhadji Barra; Maréchal, Pierre; Duflo, Hugues

    2015-09-01

    Defects may appear in composite structures during their life cycle. A 10MHz 128 elements phased array transducer was investigated to characterize join bonds and defects in sandwich honeycomb composite structures. An adequate focal law throughout the composite skin gives the ultrasonic dispersive properties of the composite skin and glue layer behind. The resulting B-scan cartographies allow characterizing locally the honeycomb adhesion. Experimental measurements are compared in good agreement with the Debye Series Method (DSM). In the processed C-scan image, flaws are detectable and measurable, localized both in the scanning plane and in the thickness of the composite skin.

  2. Expression of LAP, a SecA2-dependent secretory protein, is induced under anaerobic environment.

    PubMed

    Burkholder, Kristin M; Kim, Kwang-Pyo; Mishra, Krishna K; Medina, Sarimar; Hahm, Byoung-Kwon; Kim, Hyochin; Bhunia, Arun K

    2009-09-01

    Listeria adhesion protein (LAP), an alcohol acetaldehyde dehydrogenase homolog (lmo1634) in Listeria monocytogenes, promotes bacterial adhesion to intestinal epithelial cells in vitro. Investigation of the effect of anaerobiosis, an intrinsic gastrointestinal condition, on LAP expression and LAP-mediated infection should elucidate its significance during intestinal infection. The influence of anaerobiosis on LAP expression was determined by growing L. monocytogenes wild type (WT), and lap-deficient (KB208) and -complemented (CKB208) strains anaerobically and monitoring LAP in secreted, cell wall, and whole-cell protein fractions. The effect of anaerobiosis on LAP-mediated infection was evaluated in cell culture adhesion assays and mouse infection models. Additionally, the role of secretory system SecA2 in LAP secretion was investigated. Anaerobic growth induced significant increases in level of lap transcript and protein secretion, and secretion was SecA2-dependent. Anaerobiosis facilitated greater LAP-mediated adhesion of L. monocytogenes to cultured intestinal cells. Oral administration of WT, KB208 and CKB208 to mice confirmed that LAP is essential for full virulence, and anaerobically-grown WT exhibited greater translocation to liver and spleen relative to aerobically-grown organisms. LAP, a SecA2-dependent secreted virulence factor, plays an important role during intestinal infection, particularly when L. monocytogenes is subjected to an anaerobic environment.

  3. Adhesion of Polymer Composite Melt to PTFE at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Pan, David; Debies, Thomas; McVeigh, Dan

    2007-03-01

    A novel technique for measuring the adhesive force between a thin molten polyester composite film and a PTFE surface is presented in the paper. The molten film was prepared by first depositing powdery composite particles on a substrate and then heating the powdery film on the substrate to the test temperature through a heated pressure nip between two conformable rollers comprising a PTFE overcoat at a speed up to 400 mm/s. The adhesive force is measured by wedging a bendable metal knife into the interface between the molten film and PTFE near the exit of the heating nip. Strain gauges were mounted on both sides of the metal knife. The differential strain gauge reading resulting from the degree of the knife bending is calibrated against standard weights. The technique was used to investigate the effects of the substrate, substrate roughness, molten film thickness, temperature and type of wax additive on the adhesion of the molten composite film to PTFE. On the effects of temperature and type of wax, we found that the adhesive force remains relatively constant at low temperature, and then drops significantly, in some instances to zero, as the temperature further increases. A phenomenological model is proposed to explain the effects of main temperature and the wax additive. The model is evidenced by the surface segregation of wax from the polyester composite film as determined by XPS.

  4. Design of adhesive bonded composite-to-titanium cylindrical joints

    NASA Astrophysics Data System (ADS)

    Depasquale, F.; Ciranna, M.; Ciavatta, G.; Vittori, A.

    1993-02-01

    The ASTER composite-case solid-rocket motor (SRM) development program has addressed the problem posed by the requirement of adhesively bonding a metallic dome attach ring to the filament-wound composite case. An account is given of the numerical and experimental activities undertaken to optimize and verify the design solution, whose full opening at the aft end of the motor case facilitates mandrel extraction and propellant grain shape flexibility.

  5. Monkey pulpal response to adhesively luted indirect resin composite inlays.

    PubMed

    Inokoshi, S; Shimada, Y; Fujitani, M; Otsuki, M; Shono, T; Onoe, N; Morigami, M; Takatsu, T

    1995-01-01

    Monkey pulpal responses to resin-bonded indirect resin composite inlays were histopathologically evaluated by placing them in either etched-enamel, total-etched, or adhesive-resin-lined cavities. Initial pulpal responses caused by re-exposure of the cut dentin surfaces and luting procedure subsided if a tight marginal seal was secured by final cementation of the inlay. The adhesive resin coating of freshly cut dentinal walls/floors seems to provide a new technique to protect the dentin and pulp in indirect restorations requiring temporary sealing.

  6. Adhesive restorations: comparative evaluation between the adhesion of the glass-ceramics to the composite cement and the adhesion of the ceromer to the composite cement.

    PubMed

    Ceruti, P; Erovigni, F; Casella, F; Lombardo, S

    2005-10-01

    The aim of this work is to compare the adhesion of the glass-ceramic (empress II) to the composite cement and the adhesion of the ceromer to the composite cement. From each of the above materials, 10 little blocks, of 8 x 6 x 2 mm size, have been prepared. All the surface treatments suggested by the manufacturing industry have been performed: sandblasting and acid-etching of the ceramic, ceromer surface roughening with diamond bur and silanization and bonding application on both materials. A homogeneous layer of cement has been placed between couples of blocks of the same material and photopolymerised. Every sample, consisting of 2 bonded blocks, has been submitted to a traction force on a universal test machine connected with a computerized measure system (SINTEC D/10). Samples have been anchored to the machine binding devices by a bicomponent epoxy glue. Data on the breaking charge have been recorded and an analysis of the broken surfaces has been performed in order to classify the breaking modalities. The results ontained showed that the composite-glass-ceramic adhesion force (mean value 64 Mpa) was remarkably higher than the composite-ceromer adhesion (mean value 37.21 Mpa). The analysis of the broken surfaces by SEM showed that a mixed fracture occurred in all samples (both partly adhesive and cohesive).

  7. The Adhesive Bonding of Thermoplastic Composites

    DTIC Science & Technology

    1989-09-19

    contact angle analyses results , since both of these experimental methods attempt to assess the surface intermolecular forces . Secondly, the data from...TPFC) materials will be presented. The materials used in the present research work will then be described. Finally, the surface pretreatment...composite interface. It was precisely for the above reason that the current research work was undertaken. In the last year or two there has been some

  8. Bond strength of adhesive/composite combinations to dentin involving total- and self-etch adhesives.

    PubMed

    Molla, Karlheinz; Park, Hyun-Jung; Haller, Bernd

    2002-01-01

    To compare the bonding potential to human dentin of adhesive/composite combinations including five 2-step and two 3-step total-etch (TE) bonding systems, two systems with self-conditioning (SC) primers, and one SC all-in-one adhesive by use of the microtensile bond test. Hybrid resin composites were bonded to the occlusal dentin of 50 extracted human molars. After water storage (37 degrees C, 24 h), 31-mm-thick slabs were cut from the middle of the teeth perpendicular to their long axis. Microtensile bond strength was determined and debonded surfaces were examined under the SEM for mode of failure. GLM multivariate procedure for repeated measurements, Student-Newman-Keuls test (SPSS version 10.0; p = 0.05). Mean bond strengths of the simplified (2-step) TE systems (OptiBond Solo, Gluma One Bond, Solobond M, Prime&Bond NT, One Coat Bond; 19.9 MPa to 39.9 MPa) were not significantly lower than that of the traditional 3-step TE systems (EBS Multi: 26.0 MPa; OptiBond FL: 32.7 MPa), and not related to phosphoric acid concentration. Dentin treatment with SC primers (Clearfil Liner Bond 2: 22.0 MPa; Clearfil Liner Bond 2V: 22.4 MPa) was as effective as etching with phosphoric acid. The SC all-in-one adhesive (Etch&Prime 3.0: 10.1 MPa) produced significantly lower bond strength than all other systems evaluated. The use of adhesive/composite combinations including simplified bonding systems does not necessarily result in reduced bond strength to dentin. SC primers offer a promising alternative to phosphoric acid etching as far as bonding to dentin is concerned. In contrast, the SC all-in-one adhesive evaluated needs to be improved.

  9. SEM/XPS analysis of fractured adhesively bonded graphite fibre surface resin-rich/graphite fibre composites

    NASA Technical Reports Server (NTRS)

    Devilbiss, T. A.; Wightman, J. P.; Progar, D. J.

    1988-01-01

    Samples of graphite fiber-reinforced polyimide were fabricated allowing the resin to accumulate at the composite surface. These surface resin-rich composites were then bonded together and tested for lap shear strength both before and after thermal aging. Lap shear strength did not appear to show a significant improvement over that previously recorded for resin-poor samples and was shown to decrease with increasing aging time and temperature.

  10. The Effects of Temperature, Humidity and Aircraft Fluid Exposure on T800H/3900-2 Composites Bonded with AF-555M Adhesive

    NASA Technical Reports Server (NTRS)

    Miner, Gilda A.; Hou, Tan-Hung; Lowther, Sharon E.; Thibeault, Sheila A.; Connell, John W.; Blasini, Sheila Roman

    2010-01-01

    Fiber reinforced resin matrix composites and structural adhesives have found increased usage on commercial and military aircraft in recent years. Due to the lack of service history of these relatively new material systems, their long-term aging performance has not been well established. In this study, single lap shear specimens (SLS) were fabricated by secondary bonding of Scotch-Weld(TradeMark) AF-555M between pre-cured adherends comprised of T800H/3900-2 uni-directional laminates. The adherends were co-cured with wet peel-ply for surface preparation. Each bond-line of the SLS specimen was measured to determine thickness and inspected visually using an optical microscope for voids. A three-year environmental aging plan for the SLS specimens at 82 C (180 F) and 85% relative humidity was initiated. SLS strengths were measured for both controls and aged specimens at room temperature and 82 C. The effect of this exposure on lap shear strength and failure modes to date is reported. In addition, the effects of water, saline water, deicing fluid, JP-5 jet fuel and hydraulic fluid on both the composite material and the adhesive bonds were investigated. The up to date results on the effects of these exposures will be discussed.

  11. Adhesive Characterization and Progressive Damage Analysis of Bonded Composite Joints

    NASA Technical Reports Server (NTRS)

    Girolamo, Donato; Davila, Carlos G.; Leone, Frank A.; Lin, Shih-Yung

    2014-01-01

    The results of an experimental/numerical campaign aimed to develop progressive damage analysis (PDA) tools for predicting the strength of a composite bonded joint under tensile loads are presented. The PDA is based on continuum damage mechanics (CDM) to account for intralaminar damage, and cohesive laws to account for interlaminar and adhesive damage. The adhesive response is characterized using standard fracture specimens and digital image correlation (DIC). The displacement fields measured by DIC are used to calculate the J-integrals, from which the associated cohesive laws of the structural adhesive can be derived. A finite element model of a sandwich conventional splice joint (CSJ) under tensile loads was developed. The simulations indicate that the model is capable of predicting the interactions of damage modes that lead to the failure of the joint.

  12. Cariogenic bacteria degrade dental resin composites and adhesives.

    PubMed

    Bourbia, M; Ma, D; Cvitkovitch, D G; Santerre, J P; Finer, Y

    2013-11-01

    A major reason for dental resin composite restoration replacement is related to secondary caries promoted by acid production from bacteria including Streptococcus mutans (S. mutans). We hypothesized that S. mutans has esterase activities that degrade dental resin composites and adhesives. Standardized specimens of resin composite (Z250), total-etch (Scotchbond Multipurpose, SB), and self-etch (Easybond, EB) adhesives were incubated with S. mutans UA159 or uninoculated culture medium (control) for up to 30 days. Quantification of the BisGMA-derived biodegradation by-product, bishydroxy-propoxy-phenyl-propane (BisHPPP), was performed by high-performance liquid chromatography. Surface analysis of the specimens was performed by scanning electron microscopy (SEM). S. mutans was shown to have esterase activities in levels comparable with those found in human saliva. A trend of increasing BisHPPP release throughout the incubation period was observed for all materials and was more elevated in the presence of bacteria vs. control medium for EB and Z250, but not for SB (p < .05). SEM confirmed the increased degradation of all materials with S. mutans UA159 vs. control. S. mutans has esterase activities at levels that degrade resin composites and adhesives; degree of degradation was dependent on the material's chemical formulation. This finding suggests that the resin-dentin interface could be compromised by oral bacteria that contribute to the progression of secondary caries.

  13. Expert system for adhesive selection of composite material joints

    SciTech Connect

    Allen, R.B.; Vanderveldt, H.H.

    1994-12-31

    The development of composite joining is still in its infancy and much is yet to be learned. Consequently, this field is developing rapidly and new advances occur with great regularity. The need for up-to-date information and expertise in engineering and planning of composite materials, especially in critical applications, is acute. The American Joining Institute`s (AJI) development of JOINEXCELL (an off-line intelligent planner for joining composite materials) is an intelligent engineering/planning software system that incorporates the knowledge of several experts which can be expanded as these developments occur. Phase I effort of JOINEXCELL produced an expert system for adhesive selection, JOINADSELECT, for composite material joints. The expert system successfully selects from over 26 different adhesive families for 44 separate material types and hundreds of application situations. Through a series of design questions the expert system selects the proper adhesive for each particular design. Performing this {open_quotes}off-line{close_quotes} engineering planning by computer allows the decision to be made with full knowledge of the latest information about materials and joining procedures. JOINADSELECT can greatly expedite the joining design process, thus yielding cost savings.

  14. Cariogenic Bacteria Degrade Dental Resin Composites and Adhesives

    PubMed Central

    Bourbia, M.; Ma, D.; Cvitkovitch, D.G.; Santerre, J.P.; Finer, Y.

    2013-01-01

    A major reason for dental resin composite restoration replacement is related to secondary caries promoted by acid production from bacteria including Streptococcus mutans (S. mutans). We hypothesized that S. mutans has esterase activities that degrade dental resin composites and adhesives. Standardized specimens of resin composite (Z250), total-etch (Scotchbond Multipurpose, SB), and self-etch (Easybond, EB) adhesives were incubated with S. mutans UA159 or uninoculated culture medium (control) for up to 30 days. Quantification of the BisGMA-derived biodegradation by-product, bishydroxy-propoxy-phenyl-propane (BisHPPP), was performed by high-performance liquid chromatography. Surface analysis of the specimens was performed by scanning electron microscopy (SEM). S. mutans was shown to have esterase activities in levels comparable with those found in human saliva. A trend of increasing BisHPPP release throughout the incubation period was observed for all materials and was more elevated in the presence of bacteria vs. control medium for EB and Z250, but not for SB (p < .05). SEM confirmed the increased degradation of all materials with S. mutans UA159 vs. control. S. mutans has esterase activities at levels that degrade resin composites and adhesives; degree of degradation was dependent on the material’s chemical formulation. This finding suggests that the resin-dentin interface could be compromised by oral bacteria that contribute to the progression of secondary caries. PMID:24026951

  15. [The various families of composite adhesives: presentation and experimentation].

    PubMed

    Hitmi, Laïla; Attal, Jean-Pierre; Degrange, Michel

    2002-03-01

    Today, manufacturers provide the orthodontist with a range of adhesive systems which is so wide that is often difficult for the orthodontist to make his choice between them. The adhesive systems fall into four categories: traditional hydrophobic bonding systems, hydrophilic bonding systems, self-etching bonding systems, resin-modified glass ionomer-cements. This article will attempt to examine the first three categories which correspond to those of the composite bonding systems. Following a presentation of bonding assembling and of the required specification of the bonding systems used in orthodontic practice, the three composite bonding systems will be examined along with their advantages/disadvantages before a closing description of the corresponding clinical protocol to be followed. Whenever one of our laboratory experiments enables us to provide experimental evidence, a presentation is made within the related chapters.

  16. Effects of adhesive composite core systems on adaptation of adhesive post and cores under load.

    PubMed

    Duc, Olivier; Krejci, Ivo

    2009-08-01

    To test marginal and internal adaptation of five different adhesive composite core systems under load. 30 human premolars were endodontically prepared and obturated with an epoxy sealer and vertically condensed gutta-percha. Thereafter the entire clinical crown was removed. The teeth were randomly assigned to five different composite core groups, all using the same fiber reinforced radicular post (DT White). Gr. 1: Optibond solo plus/Nexus II/Prodigy; Gr. 2: Scotchbond 1/Rely X Arc/Filtek P60; Gr. 3: EBS multi/Compolute applicap/Pertac II; Gr. 4: ART Bond/Parapost cement/Synergy; Gr. 5: Superbond C&B catalyst S+polymer/Metafil CX. Polyvinyl-siloxane impressions of the external margins of the cores were readied before and after 1,200,000 cycles of mechanical loading with max. 100 N at 45 degrees to the longitudinal axis of the tooth. After loading, 5 of the 6 samples of each group were cut longitudinally and the sixth sample was cut transversally to be able to take replicas for evaluation of internal adaptation after loading. Percentages of external "continuous margins" ranged from 97.9+-4.6 to 66.5+-7.8 before and from 87.4+-25.0 to 5.8+-12.5 after loading. Internal adaptation ranged from 96.4+-8.0 to 17.1+-20.4 after loading for the core adaptation and from 89.8+-12.2 to 65.9+-14.3 for the dentin-luting composite interface and from 99.4+-1.2 to 88.6+-9.4 for the composite-post interface. Surprisingly, the best materials' combination for the adhesive composite core was a self-etch light cured adhesive with a chemically cured luting agent.

  17. Bond durability of self-adhesive composite cements to dentine.

    PubMed

    Suyama, Yuji; de Munck, Jan; Cardoso, Marcio Vivan; Yamada, Toshimoto; Van Meerbeek, Bart

    2013-10-01

    Clinically, the most easy-to-use composite cements are the so-called self-adhesive composite cements (SAC's). Hardly any data is however today available on the long-term bonding effectiveness of such luting composites. The purpose of this study was to evaluate the bond durability of different composite cements used to lute feldspathic ceramic blocks onto dentine. Four SAC's (Clearfil SA Cement, Kuraray; G-CEM, GC; SmartCem2, Dentsply; Unicem 3M ESPE), one 'self-etch' (Clearfil Esthetic Cement, Kuraray) and one 'etch-and-rinse' (Variolink ll, Ivoclar-Vivadent) multi-step composite cement were used to lute feldspathic ceramic blocks (Vita Mark II, Vita) onto dentine surfaces. Teeth were distributed randomly in 24 experimental groups according to two different surface-preparation techniques ('SMEAR-COVERED' versus 'SMEAR-FREE') and storage conditions ('IMMEDIATE' versus 'AGED'). Failure patterns were evaluated with a stereomicroscope, and afterwards imaged using Feg-SEM. Two additional specimens were processed for cement-dentine interfacial analysis using TEM. A linear mixed effects statistical model revealed significant differences for the variables 'composite cement', 'surface preparation' and 'ageing'. All self-adhesive composite cements, except Unicem (3M ESPE), did bond less favourably to fractured dentine. TEM revealed an ultra-structurally different interaction of the composite cements with 'SMEAR-COVERED' and 'SMEAR-FREE' dentine. All SAC's suffered most when luted to 'SMEAR-FREE' (fractured) dentine, fortunately of no clinical relevance and most likely due to enhanced water sorption through the open tubules. When luted to 'SMEAR-COVERED' dentine, all SACs appeared equally effective and durable as the 'etch-and-rinse' and 'self-etch' multi-step composite cements. Solely the SAC SmartCem2 (Dentsply) appeared clearly less favourable and consistent. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Evaluation of bond strength and thickness of adhesive layer according to the techniques of applying adhesives in composite resin restorations.

    PubMed

    de Menezes, Fernando Carlos Hueb; da Silva, Stella Borges; Valentino, Thiago Assunção; Oliveira, Maria Angélica Hueb de Menezes; Rastelli, Alessandra Nara de Souza; Conçalves, Luciano de Souza

    2013-01-01

    Adhesive restorations have increasingly been used in dentistry, and the adhesive system application technique may determine the success of the restorative procedure. The aim of this study was to evaluate the influence of the application technique of two adhesive systems (Clearfil SE Bond and Adper Scotchbond MultiPurpose) on the bond strength and adhesive layer of composite resin restorations. Eight human third molars were selected and prepared with Class I occlusal cavities. The teeth were restored with composite using various application techniques for both adhesives, according to the following groups (n = 10): group 1 (control), systems were applied and adhesive was immediately light activated for 20 seconds without removing excesses; group 2, excess adhesive was removed with a gentle jet of air for 5 seconds; group 3, excess was removed with a dry microbrushtype device; and group 4, a gentle jet of air was applied after the microbrush and then light activation was performed. After this, the teeth were submitted to microtensile testing. For the two systems tested, no statistical differences were observed between groups 1 and 2. Groups 3 and 4 presented higher bond strength values compared with the other studied groups, allowing the conclusion that excess adhesive removal with a dry microbrush could improve bond strength in composite restorations. Predominance of adhesive fracture and thicker adhesive layer were observed via scanning electron microscopy (SEM) in groups 1 and 2. For groups 3 and 4, a mixed failure pattern and thinner adhesive layer were verified. Clinicians should be aware that excess adhesive may negatively affect bond strength, whereas a thin, uniform adhesive layer appears to be favorable.

  19. Surface analysis in composite bonding

    NASA Technical Reports Server (NTRS)

    Messick, D. L.; Wightman, J. P.

    1983-01-01

    X ray photoelectron spectroscopy and contact angle measurements on graphite fiber composites pretreated in a number of different ways including mechanical, chemical, and light irradiation were analyzed. Data acquired on surface contamination as a result of fabrication techniques provides answers to the strength and durability of adhesively bonded composites. These techniques were shown to provide valuable information on surface analysis of pretreated composites prior to adhesive bonding and following lap shear fracture.

  20. Adhesive defect detection in composite adhesive joints using phased array transducers

    NASA Astrophysics Data System (ADS)

    Ren, Baiyang; Lissenden, Cliff J.

    2015-03-01

    Composite materials are widely used in aircraft structures due to their high specific stiffness and strength. The laminated nature of composite structures makes them subject to disbond and delamination. These types of defects will compromise the integrity of the structure and therefore need to be monitored. To monitor aircraft structures, light weight transducers capable of large area coverage are beneficial. Ultrasonic guided waves are able to travel long distance and are sensitive to localized defects. The multi-modal characteristic of propagating guided waves requires optimal mode selection and excitation. Phased array transducers provide good versatility for optimal mode excitation since they can excite different guided wave modes preferentially. Phased array transducers designed for structural health monitoring (SHM) applications are employed in this work to study the interaction between adhesive defects and guided wave modes. Amplitude ratios and wave packet composition are utilized as defect indicators that are uniquely available due to the phased array transducers.

  1. Electrostatic adhesion for added functionality of composite structures

    NASA Astrophysics Data System (ADS)

    Heath, Callum J. C.; Bond, Ian P.; Potter, Kevin D.

    2016-02-01

    Electrostatic adhesion can be used as a means of reversible attachment. The incorporation of electrostatic adhesion into fibre reinforced polymer (FRP) composite structures could provide significant value added functionality. Imparting large potential differences (∼2 kV) across electrodes generates an attractive force, thus providing a means of attachment. This could be used as a reversible latching mechanism or as a means of controllable internal connectivity. Varying the connectivity for discrete elements of a substructure of a given design allows for control of internal load paths and moment of area of the cross section. This could facilitate variable stiffness (both in bending and torsion). Using a combination of existing fabrication techniques, functional electrodes have been integrated within a FRP. Copper polyimide thin film laminate material has been both co-cured with carbon fibre reinforced epoxy and bonded to PVC closed cell foam core material to provide a range of structural configurations with integrated electrodes. The ability of such integrated devices to confer variations in global bending stiffness of basic beam structures is investigated. Through the application of 4 kV across integrated electrostatic adhesive devices, a 112% increase in flexural stiffness has been demonstrated for a composite sandwich structure.

  2. How cats lap: water uptake by Felis catus.

    PubMed

    Reis, Pedro M; Jung, Sunghwan; Aristoff, Jeffrey M; Stocker, Roman

    2010-11-26

    Animals have developed a range of drinking strategies depending on physiological and environmental constraints. Vertebrates with incomplete cheeks use their tongue to drink; the most common example is the lapping of cats and dogs. We show that the domestic cat (Felis catus) laps by a subtle mechanism based on water adhesion to the dorsal side of the tongue. A combined experimental and theoretical analysis reveals that Felis catus exploits fluid inertia to defeat gravity and pull liquid into the mouth. This competition between inertia and gravity sets the lapping frequency and yields a prediction for the dependence of frequency on animal mass. Measurements of lapping frequency across the family Felidae support this prediction, which suggests that the lapping mechanism is conserved among felines.

  3. Shear bond strength of new self-adhesive flowable composite resins.

    PubMed

    Wajdowicz, Michael N; Vandewalle, Kraig S; Means, Mark T

    2012-01-01

    Recently, new self-adhesive flowable composite resin systems have been introduced to the market. These new composite resin systems reportedly bond to dentin and enamel without the application of an adhesive bonding agent. The purpose of this study was to evaluate the shear bond strength to enamel of two new self-adhesive flowable composites with and without the use of an etch-and-rinse bonding agent. The new self-adhesive flowable composites had significantly lower bond strengths to enamel compared to a traditional adhesively bonded flowable composite. Both self-adhesive flowable composites had a significant increase in bond strength to enamel with the use of a phosphoric acid-etch and adhesive bonding agent.

  4. Adhesive and composite evaluation of acetylene-terminated phenylquinoxaline resins

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.

    1981-01-01

    A series of acetylene-terminated phenylquinoxaline (ATPQ) oligomers of various molecular weights were prepared and subsequently chain extended by the thermally induced reaction of the ethynyl groups. The processability and thermal properties of these oligomers and their cured resins were compared with that of a relatively high molecular weight linear polyphenylquinoxaline (PPQ) with the same chemical backbone. The ATPQ oligomers exhibited significantly better processability than the linear PPQ but the PPQ displayed substantially better thermooxidative stability. Adhesive (Ti/Ti) and composite (graphite filament reinforcement) work was performed to evaluate the potential of these materials for structural applications. The PPQ exhibited better retention of adhesive and laminate properties than the ATPQ resins at 260 C after aging for 500 hr at 260 C in circulating air.

  5. NR-150B2 adhesive development

    NASA Technical Reports Server (NTRS)

    Blatz, P. S.

    1978-01-01

    Adhesive based polyimide solutions which are more easily processed than conventional aromatic polyimide systems and show potential for use for extended times at 589K are discussed. The adhesive system is based on a solution containing diglyme as the solvent and 2,2 bis(3',4'-dicarboxyphenyl)hexafluoropropane, paraphenylenediamine, and oxydianiline. The replacement of N-methylpyrrolidone with diglyme as the solvent was found to improve the adhesive strengths of lap shear samples and simplify the processing conditions for bonding both titanium and graphite fiber/polyimide matrix resin composites. Information was obtained on the effects of various environments including high humidity, immersion in jet fuel and methylethylketone on aluminum filled adhesive bonds. The adhesive was also evaluated in wide area bonds and flatwise tensile specimens using titanium honeycomb and composite face sheets. It was indicated that the developed adhesive system has the potential for use in applications requiring long term exposure to at least 589K (600 F).

  6. Effect of different adhesion strategies on bond strength of resin composite to composite-dentin complex.

    PubMed

    Özcan, M; Pekkan, G

    2013-01-01

    Service life of discolored and abraded resin composite restorations could be prolonged by repair or relayering actions. Composite-composite adhesion can be achieved successfully using some surface conditioning methods, but the most effective adhesion protocol for relayering is not known when the composite restorations are surrounded with dentin. This study evaluated the effect of three adhesion strategies on the bond strength of resin composite to the composite-dentin complex. Intact maxillary central incisors (N=72, n=8 per subgroup) were collected and the coronal parts of the teeth were embedded in autopolymerized poly(methyl tfr54methacrylate) surrounded by a polyvinyl chloride cylinder. Cylindrical cavities (diameter: 2.6 mm; depth: 2 mm) were opened in the middle of the labial surfaces of the teeth using a standard diamond bur, and the specimens were randomly divided into three groups. Two types of resin composite, namely microhybrid (Quadrant Anterior Shine; AS) and nanohybrid (Grandio; G), were photo-polymerized incrementally in the cavities according to each manufacturer's recommendations. The composite-enamel surfaces were ground finished to 1200-grit silicone carbide paper until the dentin was exposed. The surfaces of the substrate composites and the surrounding dentin were conditioned according to one of the following adhesion protocols: protocol 1: acid-etching (dentin) + silica coating (composite) + silanization (composite) + primer (dentin) + bonding agent (dentin + composite); protocol 2: silica coating (composite) + acid-etching (dentin) + silanization (composite) + primer (dentin) + bonding agent (dentin + composite); and protocol 3: acid-etching (dentin) + primer (dentin) + silanization (composite) + bonding agent (dentin + composite). Applied primer and bonding agents were the corresponding materials of the composite manufacturer. Silica coating (CoJet sand, 30 μm) was achieved using a chairside air-abrasion device (distance: 10 mm; duration

  7. Test and analysis of Celion 3000/PMR-15, graphite/polyimide bonded composite joints: Summary

    NASA Technical Reports Server (NTRS)

    Cushman, J. B.; Mccleskey, S. F.; Ward, S. H.

    1983-01-01

    Standard single lap, double lap and symmetric step lap bonded joints of Celion 3000/PMR-15 graphite/polyimide composite were evaluated. Composite to composite and composite to titanium joints were tested at 116K (-250 F), 294K (70 F) and 561K (550 F). Joint parameters evaluated were lap length, adherend thickness, adherend axial stiffness, lamina stacking sequence and adherend tapering. Tests of advanced joint concepts were also conducted to establish the change in performance of preformed adherends, scalloped adherends and hybrid systems. Special tests were conducted to establish material properties of the high temperature adhesive, designated A7F, used for bonding. Most of the bonded joint tests resulted in interlaminar shear or peel failures of the composite. There were very few adhesive failures. Average test results agree with expected performance trends for the various test parameters. Results of finite element analyses and of test/analysis correlations are also presented.

  8. Test and analysis of Celion 3000/PMR-15, graphite/polyimide bonded composite joints: Data report

    NASA Technical Reports Server (NTRS)

    Cushman, J. B.; Mccleskey, S. F.; Ward, S. H.

    1982-01-01

    Standard single lap, double lap and symmetric step lap bonded joints of Celion 3000/PMR-15 graphite/polyimide composite were evaluated. Composite to composite and composite to titanium joints were tested at 116 K (-250 F), 294 K (70 F) and 561 K (550 F). Joint parameters evaluated are lap length, adherend thickness, adherend axial stiffness, lamina stacking sequence and adherend tapering. Advanced joint concepts were examined to establish the change in performance of preformed adherends, scalloped adherends and hybrid systems. The material properties of the high temperature adhesive, designated A7F, used for bonding were established. The bonded joint tests resulted in interlaminar shear or peel failures of the composite and there were very few adhesive failures. Average test results agree with expected performance trends for the various test parameters. Results of finite element analyses and of test/analysis correlations are also presented.

  9. Composites with improved fiber-resin interfacial adhesion

    NASA Technical Reports Server (NTRS)

    Cizmecioglu, Muzaffer (Inventor)

    1989-01-01

    The adhesion of fiber reinforcement such as high modulus graphite to a matrix resin such as polycarbonate is greatly enhanced by applying a very thin layer, suitably from 50 Angstroms to below 1000 Angstroms, to the surface of the fiber such as by immersing the fiber in a dilute solution of the matrix resin in a volatile solvent followed by draining to remove excess solution and air drying to remove the solvent. The thin layer wets the fiber surface. The very dilute solution of matrix resin is able to impregnate multifilament fibers and the solution evenly flows onto the surface of the fibers. A thin uniform layer is formed on the surface of the fiber after removal of the solvent. The matrix resin coated fiber is completely wetted by the matrix resin during formation of the composite. Increased adhesion of the resin to the fibers is observed at fracture. At least 65 percent of the surface of the graphite fiber is covered with polycarbonate resin at fracture whereas uncoated fibers have very little matrix resin adhering to their surfaces at fracture and epoxy sized graphite fibers exhibit only slightly higher coverage with matrix resin at fracture. Flexural modulus of the composite containing matrix resin coated fibers is increased by 50 percent and flexural strength by 37 percent as compared to composites made with unsized fibers.

  10. Laser Surface Preparation for Adhesive Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical pre-bonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  11. Characterization of the structure and composition of gecko adhesive setae

    PubMed Central

    Rizzo, N.W; Gardner, K.H; Walls, D.J; Keiper-Hrynko, N.M; Ganzke, T.S; Hallahan, D.L

    2005-01-01

    The ability of certain reptiles to adhere to vertical (and hang from horizontal) surfaces has been attributed to the presence of specialized adhesive setae on their feet. Structural and compositional studies of such adhesive setae will contribute significantly towards the design of biomimetic fibrillar adhesive materials. The results of electron microscopy analyses of the structure of such setae are presented, indicating their formation from aggregates of proteinaceous fibrils held together by a matrix and potentially surrounded by a limiting proteinaceous sheath. Microbeam X-ray diffraction analysis has shown conclusively that the only ordered protein constituent in these structures exhibits a diffraction pattern characteristic of β-keratin. Raman microscopy of individual setae, however, clearly shows the presence of additional protein constituents, some of which may be identified as α-keratins. Electrophoretic analysis of solubilized setal proteins supports these conclusions, indicating the presence of a group of low-molecular-weight β-keratins (14–20 kDa), together with α-keratins, and this interpretation is supported by immunological analyses. PMID:16849272

  12. Ultrasonic inspection of adhesive joints of composite pipelines

    NASA Astrophysics Data System (ADS)

    de Almeidaa, Priscila Duarte; Alcoforado Rebello, João Marcos; Pereira, Gabriela Ribeiro; Soares, Sérgio Damasceno; Fernandez, Roman

    2014-02-01

    Composite pipelines are an attractive solution when traditional materials are not suitable for this purpose, which happens frequently at aggressive environments and also where the structural weight is a limiting factor. This work studies the application of the ultrasonic technique at the detection of defects as lack of adhesive and lack of adhesion, commonly found in adhesive joints of glass fiber reinforced plastic (GFRP) pipelines applied at onshore and offshore facilities. Computational simulations were conducted in CIVA 11software (beta version) in order to obtain the best possible configuration for the inspections, applying the pulse-echo technique. Experimental results were compared to these simulations and several transducers were tested. An inspection methodology and reference blocks were developed for the calibration of the inspections. Some samples were selected for cutting in order to compare the ultrasonic results and the real condition of the joints. Results show that smaller frequencies are suitable for the inspection of this material and focused probes present more accurate results.

  13. Use of dental adhesives as modeler liquid of resin composites.

    PubMed

    Münchow, Eliseu Aldrighi; Sedrez-Porto, José Augusto; Piva, Evandro; Pereira-Cenci, Tatiana; Cenci, Maximiliano Sergio

    2016-04-01

    Resin adhesives (RA) have been applied between resin composite (RC) increments, but there is no consensus on the impact of this technique on the properties of the final restoration. This study evaluated the effect of the presence of RA between RC layers on physical properties, translucency and long-term color stability of the restorative material. Scotchbond™ Multi-Purpose (bond, 3M ESPE) and Adper™ Single Bond 2 (3M ESPE) were used as RA, and Filtek™ Z350 (3M ESPE) as RC. Specimens containing RA were prepared by applying 3 layers of the adhesive between 4 increments of RC; adhesive-free specimens were also used (control). Tests of water sorption and solubility, mechanical performance (microtensile cohesive strength, flexural strength, and flexural modulus, after immediate and long-term water storage), and translucency and color stability (after immediate and 1, 7, 90, and 180 days of water or wine storage) were performed. Scanning electron microscopy (SEM) images were also taken from the fractured specimens (flexural strength test). Data were analyzed using ANOVA and Tukey test (p<0.05). Scotchbond (SBMP) showed lower water sorption and solubility than the control (p<0.001), and an overall similar (p≥0.198, immediate tests) or higher (p≤0.019, long-term tests) mechanical performance. SBMP exhibited a rougher cross-sectional surface compared to the other groups. Translucency remained unaltered after 180 days of storage (p≥0.313), except for single bond that had increased translucency with wine storage (p<0.045). After 180 days, all groups changed color (p≤0.002), although more intensively when immersed in wine. The presence of RA within RC increments increased the physical stability of the material, being this effect more evident by using the hydrophobic unfilled adhesive resin (SBMP). This study is the first to show positive results from the use of resin adhesives as modeler liquid of resin composite, which is common in clinical practice. Copyright

  14. Fixed abrasive flat lapping with 3M Trizact diamond tile abrasive pads

    NASA Astrophysics Data System (ADS)

    Fletcher, Tim D.; Dronen, Blake; Gobena, Feben T.; Larson, Eric

    2003-05-01

    Lapping is an important dimensioning and finishing technology that is used in any different industries including metal, electronic, and optical component fabrication, as well as silicon wafer production. In each of these applications lapping is used to produce flat substrates of a controlled thickness, flatness, and surface roughness. Lapping can be performed in either a single-sided or double-sided operation. Conventional lapping technology can be divided into two basic categories: loose abrasive grinding (slurry lapping) or fixed abrasive lapping. In slurry lapping the abrasive is in the form of an aqueous slurry of abrasive minerals (typically alumina or silicon carbide) and the lapping surface is the machine platen (typically cast iron). Conventional fixed abrasive lapping is also called "pellet lapping." In this process the abrasive (typically diamond) is incorporated into small pellets (metal, vitreous, or resin bond) which are attached to cast iron machine platens. The lapping surface during pellet lapping is formed by the top surfaces of all of the pellets. Here we report on a structured abrasive lapping technology developed by 3M. The structured abrasive pad consists of an organic (polymeric binder) -- inorganic (abrasive mineral, i.e., diamond) composite and is used with coolant. Typical lapping coolants including deionized water are used as lubricants without the addition of any free abrasive mineral.

  15. Indirect aesthetic adhesive restoration with fibre-reinforced composite resin.

    PubMed

    Corona, S A M; Garcia, P P N S; Palma-Dibb, R G; Chimello, D T

    2004-10-01

    This paper describes the restoration of an endodontically treated upper first molar with a fibre-reinforced onlay indirect composite resin restoration. The clinical and radiographic examination confirmed that the tooth had suffered considerable loss of structure. Therefore, an indirect restoration was indicated. First, a core was built with resin-modified glass ionomer cement, followed by onlay preparation, mechanical/chemical gingival retraction and impression with addition-cured silicone. After the laboratory phase, the onlay was tried in, followed by adhesive bonding and occlusal adjustment. It can be concluded that fibre-reinforced aesthetic indirect composite resin restoration represented, in the present clinical case, an aesthetic and conservative treatment option. However, the use of fibres should be more extensively studied to verify the real improvement in physical and mechanical properties.

  16. Chemistry, Adhesive and Composite Properties of Low Molecular Weight Phenylethynyl Terminated Oligomers

    NASA Technical Reports Server (NTRS)

    Connell, John W.

    2004-01-01

    PETI-5 (1250 and 2500 g/mole) were prepared and characterized. Neat resin, adhesive and composite properties were determined and compared with those of PETI-5 (5000 g/mole). Relative to PETI-5 (5000 g/mole), PETI-5 (2500 g/mole) exhibited improved processability and equivalency in the adhesive and composite properties measured thus far. This resin, in both adhesive film and prepreg form, has the potential to offer significant improvements in the processing of complex structural composite parts.

  17. Chemistry, Adhesive and Composite Properties of Low Molecular Weight Phenylethynyl Terminated Oligomers

    NASA Technical Reports Server (NTRS)

    Connell, John W.

    2004-01-01

    PETI-5 (1250 and 2500 g/mole) were prepared and characterized. Neat resin, adhesive and composite properties were determined and compared with those of PETI-5 (5000 g/mole). Relative to PETI-5 (5000 g/mole), PETI-5 (2500 g/mole) exhibited improved processability and equivalency in the adhesive and composite properties measured thus far. This resin, in both adhesive film and prepreg form, has the potential to offer significant improvements in the processing of complex structural composite parts.

  18. Nondestructive inspection of CFRP adhesively bonded joints using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Webb, S.; Shin, P.; Peters, K.; Selfridge, R.; Schultz, S.

    2013-05-01

    One challenging need for inspection capabilities is in adhesively bonded joints between composite components, a common location of premature failure in aerospace structures. In this work we demonstrate that dynamic, full spectral scanning of FBG sensors embedded in the adhesive bond can identify changes in bond quality through the measurement of non-linear dynamics of the joint. Eighteen lap joint specimens were fabricated with varying manufacturing quality. Ten samples also included fiber Bragg grating (FBG) sensors embedded in the adhesive bond for real-time inspection during a simulated flight condition of these single-lap joints. Prior to testing, pulse phase thermography imaging of the pristine specimens revealed defects such as air bubbles, adhesive thickness variations, and weak bonding surface between the laminate and adhesive. The lap joint specimens were then subjected to fatigue loading, with regular interrogation of the FBG sensors at selected load cycle intervals. The FBG data was collected during vibration loading of the lap joint to represent an in-flight environment. Changes in the lap joint dynamic response, including the transition to non-linear responses, were measured from both the full-spectral and peak wavelength FBG data. These changes were correlated to initial manufacturing defects and the progression of fatigue-induced damage independently measured with pulse phase imaging and visual inspections of the failure surfaces.

  19. Further understanding of aged composite and adhesively bonded structures

    NASA Astrophysics Data System (ADS)

    Heslehurst, Rikard B.; Baird, John P.

    1996-11-01

    As the application of advanced composite materials and adhesively bonded components becomes increasingly numerous in aircraft structures, so is the number of aircraft containing such structures that can be classified in the aging aircraft category. The effect of environmental and in- service aging of such structures is not well known or understood, neither have NDE techniques been able to satisfactorily qualify and quantify the loss of structural integrity due to the aging process. This paper will present the latest developments in the practical use of a field portable holographic interferometric testing system. The system results, known as holographic interferograms, provide a better understanding of how a structure is behaving under realistic loads in the presence of defects, damage and material property aging. The system has been applied to a variety of defects in composite and adhesive bondlines, as well as artificial environmental aging of these materials. The holographic interferograms produced form these investigations will be briefly reviewed and their impact on structural integrity of the component discussed.

  20. Effects of mechanical properties of adhesive resin cements on stress distribution in fiber-reinforced composite adhesive fixed partial dentures.

    PubMed

    Yokoyama, Daiichiro; Shinya, Akikazu; Gomi, Harunori; Vallittu, Pekka K; Shinya, Akiyoshi

    2012-01-01

    Using finite element analysis (FEA), this study investigated the effects of the mechanical properties of adhesive resin cements on stress distributions in fiber-reinforced resin composite (FRC) adhesive fixed partial dentures (AFPDs). Two adhesive resin cements were compared: Super-Bond C&B and Panavia Fluoro Cement. The AFPD consisted of a pontic to replace a maxillary right lateral incisor and retainers on a maxillary central incisor and canine. FRC framework was made of isotropic, continuous, unidirectional E-glass fibers. Maximum principal stresses were calculated using finite element method (FEM). Test results revealed that differences in the mechanical properties of adhesive resin cements led to different stress distributions at the cement interfaces between AFPD and abutment teeth. Clinical implication of these findings suggested that the safety and longevity of an AFPD depended on choosing an adhesive resin cement with the appropriate mechanical properties.

  1. Experimental determination of the effects of moisture on composite-to-composite adhesive joints

    NASA Technical Reports Server (NTRS)

    Deiasi, R. J.; Schulte, R. L.

    1981-01-01

    The primary mode of moisture ingress into bonded composite joints is determined using a nuclear probe for deuterium (NPD) to measure the localized D2O content along the length of the adhesive (FM-300 and EA-9601) and through the thickness of bonded composite speciments. Calculated diffusivities and NPD measured equilibrium moisture contents are used to predict the moisture profiles along the length of the adhesives as a function of exposure time, temperature, and relative humidity. These results are compared with the observed moisture profiles to evaluate the extent of enhanced edge diffusion. The FM-300 adhesive exhibits good agreement between measured and predicted profiles at 49 C, 70% and 90% RH, and 77 C, 70% RH. At 77 C, 90% RH, the measured moisture content near the adhesive edge is substantially larger than the predicted level. The EA-9601 adhesive also shows good agreement at 49 C, 70% and 90% RH, but at 77 C, the concentration of D20 near the edges is enhanced at each humidity level. The effect of moisture content on the bond shear strength at room temperature and at elevated temperature is evaluated.

  2. Adhesion

    MedlinePlus

    ... the intestines, adhesions can cause partial or complete bowel obstruction . Adhesions inside the uterine cavity, called Asherman syndrome , ... 1. Read More Appendicitis Asherman syndrome Glaucoma Infertility Intestinal obstruction Review Date 4/5/2016 Updated by: Irina ...

  3. Adhesions

    MedlinePlus

    Adhesions are bands of scar-like tissue. Normally, internal tissues and organs have slippery surfaces so they can shift easily as the body moves. Adhesions cause tissues and organs to stick together. They ...

  4. Evaluation of adhesively bonded composites by nondestructive techniques

    NASA Astrophysics Data System (ADS)

    Malinowski, Paweł H.; Ecault, Romain; Wandowski, Tomasz; Ostachowicz, Wiesław M.

    2017-04-01

    Composite materials are commonly used in many branches of industry. One method to join or repair CFRP parts is by the use adhesive bonding. There is a search of effective methods for pre-bond assessment of bonded parts and post-bond inspection. Research reported here focuses on post-bond inspection of bonded CFRP plates. In this paper we reported results of two methods. We used noncontact ultrasonic testing (UT) technique as reference method. Ultrasonic testing was made in an immersion tank using phased-array probes. The second method was the electromechanical impedance (EMI). A piezoelectric sensors were surface mounted on each of the samples. Due to piezoelectric effect the electrical response of the sensor is related to mechanical response of the structure to which the sensors is bonded to. Measurements were conducted using HIOKI Impedance Analyzer IM3570. In order to perform a detailed study three samples of each kind were tested. There were three reference samples. The samples with modified adhesive bonds had three levels of severity, so there were three samples with each level of modification. The ultrasonic testing was focused on C-scan analysis taking into consideration the amplitude and time of flight (TOF). Two probes were used, one with 5 MHz frequency, second with 10 MHz. The EMI spectra were gathered up to 5 MHz and they were processed with signal processing algorithms in order to extract differences between reference samples and samples with modified bonds. The UT results provided relevant information about the investigated samples, while the EMI showed sensitivity to the level of adhesive bond modification.

  5. Permeability testing of composite material and adhesive bonds for the DC-XA composite feedline program

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    1995-01-01

    Hercules IM7/8552 carbon/epoxy and Hysol EA 9394 epoxy adhesive bonded between composite/titanium were tested for permeability after various numbers of thermal cycles between 100 C and liquid nitrogen (-196 C). The specimens were quenched from the 100 C temperature into liquid nitrogen to induce thermal shock into the material. Results showed that the carbon/epoxy system was practically impermeable even after 12 thermal cycles. The EA 9394 adhesive bondline was more permeable than the carbon/epoxy, but vacuum mixing minimized the permeability and kept it within allowable limits. Thermal cycling had little effect on the permeability values of the bondline specimens.

  6. Clinical approach to anterior adhesive restorations using resin composite veneers.

    PubMed

    Mangani, Francesco; Cerutti, Antonio; Putignano, Angelo; Bollero, Raffaele; Madini, Lorenzo

    2007-01-01

    Scientific progress in adhesive dentistry has led to more conservative techniques, both direct and indirect, to solve esthetic problems in anterior teeth. This article will discuss only indirect techniques, which are clearly superior in complex cases in which it will be difficult to recreate harmonious tooth shape and color. After reviewing the literature and highlighting the properties of this technique, the indications and benefits compared to the direct technique will be assessed. This is followed by a step-by-step description of operative procedures, from treatment planning to relining and polishing of the cemented adhesive restoration. The long-term success of veneers depends mainly on the tooth preparation, which should be confined to enamel, involve proximal contact areas, maintain the cervical enamel margin, and incorporate the incisal edge to increase veneer resistance and enable correct placement. Although no clinical follow-up similar to that of ceramic materials is available, the latest-generation resin composites offer interesting features. They can withstand mechanical stress, have excellent esthetic properties, and, most importantly, can be repaired intraorally without impairing their physicochemical and mechanical properties.

  7. Nondestructive inspection in adhesive-bonded joint CFRP using pulsed phase thermography

    NASA Astrophysics Data System (ADS)

    Shin, P. H.; Webb, S. C.; Peters, K. J.

    2013-05-01

    Many forms of damages in fiber reinforcement polymer (FRP) composites are difficult to detect because they occurs in subsurface layers of the composites. One challenging need for inspection capabilities is in adhesively bonded joints between composite components, a common location of premature failure in aerospace structures. This paper investigates pulsed phase thermography (PPT) imaging of fatigue damage in these adhesively bonded joints. Simulated defects were created to calibrate parameters for fatigue loading conditions, PPT imaging parameters, and a damage sizing algorithm for carbon fiber reinforced polymer (CFRP) single lap joints. Afterwards, lap joint specimens were fabricated with varying quality of manufacturing. PPT imaging of the pristine specimens revealed defects such as air bubbles, adhesive thickness variations, and weak bonding surface between the laminate and adhesive. Next, fatigue testing was performed and acquired PPT imaging data identified fatigue induced damage prior to final failure cycles. After failure of each sample, those images were confirmed by visual inspections of failure surface.

  8. Influence of interphase morphology on adhesion and composite durability in semicrystalline polymer matrix composites

    SciTech Connect

    Clark, R.L. Jr.; Kander, R.G.

    1996-12-31

    The microstructure of the interphase in semicrystalline polymer matrix composites has a dramatic influence on their mechanical properties. Studies have been performed to alter this region and to correlate various interphase morphologies with changes in fiber-matrix adhesion. A reinforced nylon 66 composite, when subjected to specific thermal histories, contains an interphase composed of transcrystallinity. This region has been altered by coating fibers with a diluent, poly(vinyl pyrrolidone), and/or adding the diluent to the matrix material in very small quantities. Interphase morphology was investigated with optical microscopy, and adhesion was measured using a modified fiber pull-out test. It was found that transcrystallinity increases the interfacial shear strength. The effect different interphase morphologies have on the durability of bulk composite samples is currently under investigation.

  9. Clinical dental adhesive application: the influence on composite-enamel interface morphology.

    PubMed

    Matei, Ruxandra; Popescu, Mihai Raul; Suciu, Mircea; Rauten, Anne Marie

    2014-01-01

    Although the adhesion phenomenon is crucial in achieving and maintaining a composite building on dental structure, this phenomenon is not completely understood. On the other hand, adhesion is dependent on the interface quality (the interface between enamel and adhesive). In this study, the authors approached the subject of the influence of adhesive clinical application on the composite-enamel interface, which was less investigated by the scientists. On intact extracted human teeth were prepared enamel areas, and then filled with light-curing composite. The teeth were sectioned and prepared for microscopic investigation, at 10×, 100× and 200× magnifications.

  10. Bond Strength of Methacrylate-Based Composite to Dentin using a Silorane Adhesive

    DTIC Science & Technology

    2013-06-06

    Lambrechts P, Vanherle G. Adhesion to enamel and dentin: current status and future challenges. Oper Dent 2003;28:215-235. Van Meerbeek B...Composite to Dentin using Silorane Adhesive is appropriately acknowledged and , beyond brief excerpts, is with the permission of the copyright owner...Based Composite to Dentin Using a Si lorane Adhesive 7. Intended publication/meeting: Presented as a poster at the International Association of

  11. [Sample German LAPS.

    ERIC Educational Resources Information Center

    Rosenthal, Bianca

    Four learning activity packages (LAPS) for use in secondary school German programs contain instructional materials which enable students to improve their basic linguistic skills. The units include: (1) "Grusse," (2) "Ich Heisse...Namen," (3) "Tune into Your Career: Business Correspondence 'Auf Deutch'," and (4) "Understanding German Culture."…

  12. Template assisted surface microstructuring of flowable dental composites and its effect on microbial adhesion properties.

    PubMed

    Frenzel, Nadja; Maenz, Stefan; Sanz Beltrán, Vanesa; Völpel, Andrea; Heyder, Markus; Sigusch, Bernd W; Lüdecke, Claudia; Jandt, Klaus D

    2016-03-01

    Despite their various advantages, such as good esthetic properties, absence of mercury and adhesive bonding to teeth, modern dental composites still have some drawbacks, e.g., a relatively high rate of secondary caries on teeth filled with composite materials. Recent research suggests that microstructured biomaterials surfaces may reduce microbial adhesion to materials due to unfavorable physical material-microbe interactions. The objectives of this study were, therefore, to test the hypotheses that (i) different surface microstructures can be created on composites by a novel straightforward approach potentially suitable for clinical application and (ii) that these surface structures have a statistically significant effect on microbial adhesion properties. Six different dental composites were initially tested for their suitability for microstructuring by polydimethylsiloxane (PDMS) templates. Each composite was light-cured between a glass slide and a microstructured PDMS template. The nano-hybrid composite Grandio Flow was the only tested composite with satisfying structurability, and was therefore used for the bacterial adhesion tests. Composites samples were structured with four different microstructures (flat, cubes, linear trapezoid structures, flat pyramids) and incubated for 4h in centrifuged saliva. The bacterial adherence was then characterized by colony forming units (CFUs) and scanning electron microscopy (SEM). All four microstructures were successfully transferred from the PDMS templates to the composite Grandio Flow. The CFU-test as well as the quantitative analysis of the SEM images showed the lowest bacterial adhesion on the flat composite samples. The highest bacterial adhesion was observed on the composite samples with linear trapezoid structures, followed by flat pyramids and cubes. The microstructure of dental composite surfaces statistically significantly influenced the adhesion of oral bacteria. Modifying the composite surface structure may be

  13. Interfacial adhesion in rayon/nylon sheath/core composite fibers

    SciTech Connect

    Tao Weiying.

    1991-01-01

    The fibers with enhanced adhesion were produced using a wire coating type process. One objective was to determine an effective coupling agent and the most-appropriate application conditions for maximum interfacial adhesion in the rayon/nylon bicomponent fibers. The second objective was to characterize the interfacial adhesion between the core fiber and the rayon skin. After removal of the spin finish by water washing, the nylon core fibers were pretreated with fumaric acid (FA) as an adhesion promoter and then were coated with viscose rayon. The results indicated that the interfacial adhesion in the rayon/nylon composite fibers was significantly improved under the application conditions of 1.0% with 36 second pretreatment time, 1.5% with 18 second pretreatment, and 2% with 9 second pretreatment time. A fiber pull adhesion test method was developed to test the interfacial adhesion. This method effectively determined the adhesion between the core and the skin.

  14. Characterization of EA9394 Adhesive for Repair Applications

    DTIC Science & Technology

    1994-01-01

    examined briefly. The resistance of the bond-4 joint system appears to be heavily dependent upon the thickness of the metal adherend exposed to the...applications for aluminum and/or composite structures. The study includes data on the effects of time, pressure, and temperature on adhesive tensile lap shear...1992. It was caried out under Air Force Contmacts No. F33615-86-C-5031, " Composites Supportability Rapid Test and Evaluation," and No. F33615-89-C

  15. AMORPHOUS CALCIUM PHOSPHATE COMPOSITES AND THEIR EFFECT ON COMPOSITE-ADHESIVE-DENTIN BONDING

    PubMed Central

    Antonucci, J.M.; O’Donnell, J.N.R.; Schumacher, G.E.; Skrtic, D.

    2009-01-01

    This study evaluates the bond strength and related properties of photo-polymerizable, remineralizing amorphous calcium phosphate (ACP) polymeric composite-adhesive systems to dentin after various periods of aqueous aging at 37 °C. An experimental ACP base and lining composite was made from a photo-activated resin comprising 2,2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy)phenyl]propane (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and zirconyl dimethacrylate (ZrDMA); designated BTHZ. An experimental orthodontic composite was formulated from a photo-activated resin comprising ethoxylated bisphenol A dimethacrylate (EBPADMA), TEGDMA, HEMA and methacryloxyethyl phthalate (MEP); designated ETHM. In both composite series three fillers were compared: 1) freshly precipitated zirconium-modified ACP freshly precipitated (as-prepared Zr-ACP), 2) milled Zr-ACP and 3) an ion-leachable fluoride glass. In addition to the shear bond strength (SBS), work to fracture and failure modes of the orthodontic composites were determined. The SBS of the base and lining ACP composites appeared unaffected by filler type or immersion time. In the orthodontic ACP composite series, milled ACP composites showed initial mechanical advantages over as-prepared ACP composites, and produced higher incidence of a failure mode consistent with stronger adhesion. After six months of aqueous exposure, 80 % of specimens failed at the dentin-primer interface, with a 42 % overall reduction in bond strength. BTHZ and ETHM based ACP composites are potentially effective anti-demineralizing-remineralizing agents with possible clinical utility as protective base-liners and orthodontic cements, respectively. The analysis of the bond strength and failure modalities suggests that milled ACP composites may offer greater potential in clinical applications. PMID:19696914

  16. Choice of the Theory of Adhesive Interactions for Modeling Interlayer Cracks in Composites

    NASA Astrophysics Data System (ADS)

    Belov, P. A.; Nelub, V. A.

    2016-01-01

    An analysis is carried out and a choice between two continual theories of adhesive interactions which can be used for modeling cracks on the contact surface of phases in fibrous composites is made. It is shown that, within the frameworks of the adhesion theories — the Gurtin-Murdoch surface elasticity theory and the Belov-Lurie theory of ideal adhesion — the statements of boundary problems for shear (Mode II) and tear cracks (Mode III) are identical, but for the cracks of normal separation (Mode I), the adhesive properties can be taken into account only in the theory of ideal adhesion.

  17. New primers for adhesive bonding of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Burrell, B. W.; Port, W. S.

    1971-01-01

    Synthetic polypeptide adhesive primers are effective, with high temperature epoxy resins, at temperatures from 100 deg to 300 deg C. Lap-shear failure loads and lap-shear strength of both primers are discussed.

  18. [Studies on the pre-treatment of dental alloy for adhesive restorations. 4. Adhesive durability of adhesive resin to various dental alloys treated with composite plating].

    PubMed

    Kondo, Y; Yamashita, A; Suzuki, K; Omura, I; Yamauchi, J I

    1989-07-01

    In this study, the durability of adhesion between an adhesive resin (Panavia EX) and dental alloys (gold or Ni-Cr) were examined in regard to thermal cycling, immersion, either in water (70 degrees C or 100 degrees C) or in sodium chloride solutions (pH was 3, 7 and 9). An favourable adhesive strength, such as 450-500 kgf/cm2, was obtained even after 24 hours immersion in 37 degrees C water, when the surface pre-treatment of the alloy was done with either Sn- or composite (TMSAC/Sn or PVC/Sn)-plating. However, during the durability test, the adhesive strength has decreased to such on extent, that about 60% of early strength with Sn-plating and 80% with TMSAC/Sn composite plating. But, with PVC/Sn composite-plating, more than 90% of the early strength was maintained. In regard to the pH of the corrosive solution, no apparent difference was observed regarding the above mentioned adhesive characteristics.

  19. Viscoelastic Properties of Collagen-Adhesive Composites under Water Saturated and Dry Conditions

    PubMed Central

    Singh, Viraj; Misra, Anil; Parthasarathy, Ranganathan; Ye, Qiang; Spencer, Paulette

    2014-01-01

    To investigate the time and rate dependent mechanical properties of collagen-adhesive composites, creep and monotonic experiments are performed under dry and wet conditions. The composites are prepared by infiltration of dentin adhesive into a demineralized bovine dentin. Experimental results show that for small stress level under dry conditions, both the composite and neat adhesive have similar behavior. On the other hand, in wet conditions, the composites are significantly soft and weak compared to the neat adhesives. The behavior in the wet condition is found to be affected by the hydrophilicity of both the adhesive and collagen. Since the adhesive-collagen composites area part of the complex construct that forms the adhesive-dentin interface, their presence will affect the overall performance of the restoration. We find that Kelvin-Voigt model with at least 4-elements is required to fit the creep compliance data, indicating that the adhesive-collagen composites are complex polymers with several characteristics time-scales whose mechanical behavior will be significantly affected by loading rates and frequencies. Such mechanical properties have not been investigated widely for these types of materials. The derived model provides an additional advantage that it can be exploited to extract other viscoelastic properties which are, generally, time consuming to obtain experimentally. The calibrated model is utilized to obtain stress relaxation function, frequency-dependent storage and loss modulus, and rate dependent elastic modulus. PMID:24753362

  20. Microleakage of Class II composite resin restorations with self-adhesive composite resin liners.

    PubMed

    Doozandeh, Maryam; Shafiei, Fereshteh; Mohammadi, Fatemeh

    2017-01-01

    This study investigated the microleakage of Class II composite restorations with composite resin liners. Standardized box cavities were prepared on the mesial and distal surfaces of 84 extracted intact human molars. Proximal margins were located in enamel (occlusal) and 1.0 mm apical to the cementoenamel junction (gingival). The teeth were randomly divided into 6 groups (n = 28 cavities) and restored with Filtek Z350 nanohybrid composite resin (FZ). The test groups were lined with a conventional flowable composite resin, Premise Flowable (PF), or 1 of 2 self-adhesive composites (SACs): Vertise Flow (VF) or Clearfil SA luting cement (CSA) with or without their respective self-etching adhesives: Optibond All-in-One (OB) or Clearfil SE Bond (CSE). The adhesive/lining procedure was performed as follows: OB/FZ (control), OB/PF/FZ, VF/FZ, OB/VF/FZ, CSA/FZ, or CSE/CSA/FZ. Microleakage was evaluated at the occlusal and gingival margins using a dye penetration technique and quantitative assessment. Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data at the significance level of α = 0.05. None of the restorative techniques was capable of preventing microleakage completely. The greatest amount of microleakage was detected in the VF/FZ and CSA/FZ groups at both margins (P < 0.02). Among the groups placed with a bonding agent, OB/VF/FZ showed significantly greater values of microleakage at the occlusal margins than did OB/FZ, OB/PF/FZ, and CSE/CSA/FZ (P < 0.05). At the gingival margins, the OB/PF/FZ group exhibited the least leakage compared with the OB/VF/FZ and CSE/CSA/FZ groups (P < 0.001). The results indicated that the additional application of bonding agents improved the marginal sealing of SACs in Class II composite restorations.

  1. The effect of delayed placement of composite and double application of single-bottle adhesives on microleakage of composite restorations.

    PubMed

    Shafiei, Fereshteh; Kiomarsi, Nazanin; Alavi, Ali Asghar

    2011-01-01

    This study evaluated the effect of delayed placement of composite and double application of adhesive on microleakage of two-step, total-etch (single-bottle) adhesives. Standard Class V cavities were prepared in 140 sound premolars and randomly assigned into 10 groups (n = 14). Excite, Optibond Solo Plus, and Adper Scotchbond Multi-Purpose (as a control) were used. After the first layer of single-bottle adhesive was photocured, the adhesive was reapplied and photocured in four of the groups. A microhybrid composite was applied in five of the groups immediately after the adhesive was photocured; in the other five groups, the composite was placed after a three-minute delay. After 24 hours of storage in distilled water and thermocycling, the samples were placed in 1% methylene blue. All samples then were sectioned longitudinally and evaluated for microleakage at the occlusal and gingival margins under a stereomicroscope at 20x magnification. Data were analyzed using nonparametric tests. Delayed placement of composite significantly increased leakage at the gingival margins when single-bottle adhesives were used (p < 0.05). Double application of the single-bottle adhesives significantly reduced leakage at the gingival margin when placement of the composite was delayed. There was no significant difference between single and double application when the composite was placed immediately (p < 0.05).

  2. Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors.

    PubMed

    Drotlef, Dirk-M; Amjadi, Morteza; Yunusa, Muhammad; Sitti, Metin

    2017-07-01

    A facile approach is proposed for superior conformation and adhesion of wearable sensors to dry and wet skin. Bioinspired skin-adhesive films are composed of elastomeric microfibers decorated with conformal and mushroom-shaped vinylsiloxane tips. Strong skin adhesion is achieved by crosslinking the viscous vinylsiloxane tips directly on the skin surface. Furthermore, composite microfibrillar adhesive films possess a high adhesion strength of 18 kPa due to the excellent shape adaptation of the vinylsiloxane tips to the multiscale roughness of the skin. As a utility of the skin-adhesive films in wearable-device applications, they are integrated with wearable strain sensors for respiratory and heart-rate monitoring. The signal-to-noise ratio of the strain sensor is significantly improved to 59.7 because of the considerable signal amplification of microfibrillar skin-adhesive films. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Revisiting the Numerical Convergence of Cohesive-Zone Models in Simulating the Delamination of Composite Adhesive Joints by Using the Finite-Element Analysis

    NASA Astrophysics Data System (ADS)

    Liu, P. F.; Gu, Z. P.; Hu, Z. H.

    2016-11-01

    Delamination is the dominating failure mechanism in composite adhesive joints. A deep insight into the delamination failure mechanism requires advanced numerical methods. Currently, cohesive-zone models (CZMs), in combination with the finite-element analysis (FEA), have become powerful tools for modeling the initiation and growth of delaminations in composites. However, ensuring the numerical convergence in the CZMs used for a delamination analysis of three-dimensional (3D) composite structures is always a challenging issue due to the "snap-back" instability in the nonlinear implicit FEA, which arises mainly from the cohesive softening behavior. Based on the midplane interpolation technique, first numerical techniques for implementing 3D bilinear and exponential CZMs by using ABAQUS-UEL (user element subroutine) are developed in this paper. In particular, a viscous regularization by introducing the damping effect into the stiffness equation is used to improve the convergence. Two examples, a single-lap composite joint and a composite skin/stiffener panel under tension, demonstrate the numerical technique developed. Then, the effect of cohesion parameters on the numerical convergence based on the viscous regularization is studied.

  4. Bond strength of self-adhesive resin cements to composite submitted to different surface pretreatments

    PubMed Central

    dos Santos, Victor Hugo; Griza, Sandro; de Moraes, Rafael Ratto

    2014-01-01

    Objectives Extensively destroyed teeth are commonly restored with composite resin before cavity preparation for indirect restorations. The longevity of the restoration can be related to the proper bonding of the resin cement to the composite. This study aimed to evaluate the microshear bond strength of two self-adhesive resin cements to composite resin. Materials and Methods Composite discs were subject to one of six different surface pretreatments: none (control), 35% phosphoric acid etching for 30 seconds (PA), application of silane (silane), PA + silane, PA + adhesive, or PA + silane + adhesive (n = 6). A silicone mold containing a cylindrical orifice (1 mm2 diameter) was placed over the composite resin. RelyX Unicem (3M ESPE) or BisCem (Bisco Inc.) self-adhesive resin cement was inserted into the orifices and light-cured. Self-adhesive cement cylinders were submitted to shear loading. Data were analyzed by two-way ANOVA and Tukey's test (p < 0.05). Results Independent of the cement used, the PA + Silane + Adhesive group showed higher microshear bond strength than those of the PA and PA + Silane groups. There was no difference among the other treatments. Unicem presented higher bond strength than BisCem for all experimental conditions. Conclusions Pretreatments of the composite resin surface might have an effect on the bond strength of self-adhesive resin cements to this substrate. PMID:24516824

  5. Bond strength of self-adhesive resin cements to composite submitted to different surface pretreatments.

    PubMed

    Dos Santos, Victor Hugo; Griza, Sandro; de Moraes, Rafael Ratto; Faria-E-Silva, André Luis

    2014-02-01

    Extensively destroyed teeth are commonly restored with composite resin before cavity preparation for indirect restorations. The longevity of the restoration can be related to the proper bonding of the resin cement to the composite. This study aimed to evaluate the microshear bond strength of two self-adhesive resin cements to composite resin. COMPOSITE DISCS WERE SUBJECT TO ONE OF SIX DIFFERENT SURFACE PRETREATMENTS: none (control), 35% phosphoric acid etching for 30 seconds (PA), application of silane (silane), PA + silane, PA + adhesive, or PA + silane + adhesive (n = 6). A silicone mold containing a cylindrical orifice (1 mm(2) diameter) was placed over the composite resin. RelyX Unicem (3M ESPE) or BisCem (Bisco Inc.) self-adhesive resin cement was inserted into the orifices and light-cured. Self-adhesive cement cylinders were submitted to shear loading. Data were analyzed by two-way ANOVA and Tukey's test (p < 0.05). Independent of the cement used, the PA + Silane + Adhesive group showed higher microshear bond strength than those of the PA and PA + Silane groups. There was no difference among the other treatments. Unicem presented higher bond strength than BisCem for all experimental conditions. Pretreatments of the composite resin surface might have an effect on the bond strength of self-adhesive resin cements to this substrate.

  6. Functionally gradient hard carbon composites for improved adhesion and wear

    NASA Astrophysics Data System (ADS)

    Narayan, Roger Jagdish

    A new approach is proposed for fabricating biomedical devices that last longer and are more biocompatible than those presently available. In this approach, a bulk material is chosen that has desirable mechanical properties (low modulus, high strength, high ductility and high fatigue strength). This material is coated with corrosion-resistant, wear-resistant, hard, and biocompatible hard carbon films. One of the many forms of carbon, tetrahedral amorphous carbon, consists mainly of sp3-bonded atoms. Tetrahedral amorphous carbon possesses properties close to diamond in terms of hardness, atomic smoothness, and inertness. Tetrahedral amorphous carbon and diamond films usually contain large amounts of compressive and sometimes tensile stresses; adhesive failure from these stresses has limited widespread use of these materials. This research involves processing, characterization and modeling of functionally gradient tetrahedral amorphous carbon and diamond composite films on metals (cobalt-chromium and titanium alloys) and polymers (polymethylmethacrylate and polyethylene) used in biomedical applications. Multilayer discontinuous thin films of titanium carbide, titanium nitride, aluminum nitride, and tungsten carbide have been developed to control stresses and graphitization in diamond films. A morphology of randomly interconnected micron sized diamond crystallites provides increased toughness and stress reduction. Internal stresses in tetrahedral amorphous carbon were reduced via incorporation of carbide forming elements (silicon and titanium) and noncarbide forming elements (copper, platinum, and silver). These materials were produced using a novel target design during pulsed laser deposition. These alloying atoms reduce hardness and sp3-bonded carbon content, but increase adhesion and wear resistance. Silver and platinum provide the films with antimicrobial properties, and silicon provides bioactivity and aids bone formation. Bilayer coatings were created that couple

  7. Urea modified cottonseed protein adhesive for wood composite products

    USDA-ARS?s Scientific Manuscript database

    Cottonseed protein has the potential to be used as renewable and environmentally friendly adhesives in wood products industry. However, the industry application was limited by its low mechanical properties, low water resistance and viscosity. In this work, urea modified cottonseed protein adhesive w...

  8. A novel addition polyimide adhesive

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.; Progar, D. J.

    1981-01-01

    An addition polyimide adhesive, LARC 13, was developed which shows promise for bonding both titanium and composites for applications which require service temperatures in excess of 533 K. The LARC 13 is based on an oligomeric bis nadimide containing a meta linked aromatic diamine. The adhesive melts prior to polymerization due to its oligomeric nature, thereby allowing it to be processed at 344 kPa or less. Therefore, LARC 13 is ideal for the bonding of honeycomb sandwich structures. After melting, the resin thermosets during the cure of the nadic endcaps to a highly crosslinked system. Few volatiles are evolved, thus allowing large enclosed structures to be bonded. Preparation of the adhesive as well as bonding, aging, and testing of lap shear and honeycomb samples are discussed.

  9. Composites Supportability Rapid Test and Evaluation

    DTIC Science & Technology

    1990-05-01

    Primer .......................... 85 33 A357 Chemical Composition ................................ 86 34 A357 Heat Treatment...88 37 Tensile Lap Shear Data, A357 Cast Aluminum vs. 2024-T3 Sheet Aluminum...89 38 Wedge Crack Growth Data, 250OF Curing Adhesive System, A357 Cast Aluminum vs. 2024-T3 Sheet Aluminum .............. 90 39 Wedge Crack Growth

  10. Adhesive strength of paint-on resins to crown and bridge composites.

    PubMed

    Kanie, Takahito; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

    2004-12-01

    This paper examined the adhesive strength of paint-on resin to crown and bridge composites after soaking in water and thermal-cycling. Three shades of paint-on resin were coated on three kinds of crown and bridge composite under four surface treatment conditions (a combination of sandblaster and pretreatment liquid). These specimens were soaked in water at 37 degrees C for 1 day, 1 month, and 1 year, and at 4 degrees C and 60 degrees C alternatively for 1-minute periods for 10,000 cycles by thermal-cycling machine. The adhesive strengths were obtained by shear test. There were no significant differences among the adhesive strengths of three shades of paint-on resin to three composites after storage (p > 0.05). The adhesive strengths to composites with sandblasting showed higher values than those without it (p < 0.01).

  11. Analysis of the Static and Fatigue Strenght of a Damage Tolerant 3D-Reinforced Joining Technology on Composite Single Lap Joints

    NASA Astrophysics Data System (ADS)

    Nogueira, A. C.; Drechsler, K.; Hombergsmeier, E.

    2012-07-01

    The increasing usage of carbon fiber reinforced plastics (CFRP) in aerospace together with the constant drive for fuel efficiency and lightweight design have imposed new challenges in next generation structural assemblies and load transfer efficient joining methods. To address this issue, an innovative technology, denominated Redundant High Efficiency Assembly (RHEA) joints, is introduced as a high-performance lightweight joint that combines efficient load transfer with good damage tolerance. A review of the ongoing research involving the RHEA joint technology, its through-thickness reinforcement concept and the results of quasi-static and fatigue tensile investigations of single lap shear specimens are exposed and discussed. Improvements in ultimate static load, maximum joint deformation, damage tolerance and fatigue life are encountered when comparing the performance of the RHEA lap shear joints to co-bonded reference specimens.

  12. Surface Morphology and Tooth Adhesion of a Novel Nanostructured Dental Restorative Composite.

    PubMed

    Salerno, Marco; Loria, Patrizia; Matarazzo, Giunio; Tomè, Francesco; Diaspro, Alberto; Eggenhöffner, Roberto

    2016-03-16

    Recently, a novel dental restorative composite based on nanostructured micro-fillers of anodic porous alumina has been proposed. While its bulk properties are promising thanks to decreased aging and drug delivery capabilities, its surface properties are still unknown. Here we investigated the surface morphology and the adhesion to tooth dentin of this composite as prepared. For comparison, we used two commercial composites: Tetric EVO Flow (Ivoclar) and Enamel HRi Plus (Micerium). The surface morphology was characterized by atomic force microscopy and the adhesion strength by tensile tests. The experimental composite is rougher than the commercial composites, with root mean square roughness of ~549 nm against 170-511 nm, and presents an adhesion strength of ~15 MPa against 19-21 MPa. These results show at the same time some proximity to the commercial composites, but also the need for optimization of the experimental material formulation.

  13. Characterization of mode 1 and mixed-mode failure of adhesive bonds between composite adherends

    NASA Technical Reports Server (NTRS)

    Mall, S.; Johnson, W. S.

    1985-01-01

    A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue beyond growth mechanism under mode 1 and mixed-mode 1 and 2 loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: a double-cantilever-beam specimen for mode 1 loading and a cracked-lapshear specimen for mixed-mode 1 and 2 loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under mixed-mode 1 and 2 loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under mode 1 loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.

  14. Composition and Humidity Response of the Black Widow Spider's Gumfoot Silk and its Implications on Adhesion

    NASA Astrophysics Data System (ADS)

    Jain, Dharamdeep; Zhang, Ci; Cool, Lydia Rose; Blackledge, Todd. A.; Wesdemiotis, Chrys; Miyoshi, Toshikazu; Dhinojwala, Ali

    Humidity plays an important part in the performance of biomaterials such as pollen, gecko toe, wheat awns, bird feathers and dragline silk. Capture silk produced by web building spiders form an interesting class of humidity responsive biological glues. The adhesive properties of the widely studied `viscid silk' produced by orbweb-weaving spiders is highly humidity sensitive. On the other hand, relatively less is known about the dependence of composition and humidity response towards adhesion for `gumfoot' silk produced by cobweb-weaving spiders. In the present study, we investigate the gumfoot silk produced by Black Widow using adhesion mechanics, microscopy and spectroscopic methods. The results show the presence of hygroscopic salts, glycoproteins and previously known spider coating peptides in silk and their importance in the humidity response and adhesion. The current study elucidates the role of constituents of capture silk in its adhesion mechanism and offers insights to novel ways for fabricating bio-inspired adhesives.

  15. Structural and compositional characterization of the adhesive produced by reef building oysters.

    PubMed

    Alberts, Erik M; Taylor, Stephen D; Edwards, Stephanie L; Sherman, Debra M; Huang, Chia-Ping; Kenny, Paul; Wilker, Jonathan J

    2015-04-29

    Oysters have an impressive ability to overcome difficulties of life within the stressful intertidal zone. These shellfish produce an adhesive for attaching to each other and building protective reef communities. With their reefs often exceeding kilometers in length, oysters play a major role in balancing the health of coastal marine ecosystems. Few details are available to describe oyster adhesive composition or structure. Here several characterization methods were applied to describe the nature of this material. Microscopy studies indicated that the glue is comprised of organic fiber-like and sheet-like structures surrounded by an inorganic matrix. Phospholipids, cross-linking chemistry, and conjugated organics were found to differentiate this adhesive from the shell. Symbiosis in material synthesis could also be present, with oysters incorporating bacterial polysaccharides into their adhesive. Oyster glue shows that an organic-inorganic composite material can provide adhesion, a property especially important when constructing a marine ecosystem.

  16. Shear Bond Strength between Fiber-Reinforced Composite and Veneering Resin Composites with Various Adhesive Resin Systems.

    PubMed

    AlJehani, Yousef A; Baskaradoss, Jagan K; Geevarghese, Amrita; AlShehry, Marey A; Vallittu, Pekka K

    2016-07-01

    The aim of this research was to evaluate the shear bond strength of different laboratory resin composites bonded to a fiber-reinforced composite substrate with some intermediate adhesive resins. Mounted test specimens of a bidirectional continuous fiber-reinforced substrate (StickNet) were randomly assigned to three equal groups. Three types of commercially available veneering resin composites - BelleGlass®, Sinfony®, and GC Gradia® were bonded to these specimens using four different adhesive resins. Half the specimens per group were stored for 24 hours; the remaining were stored for 30 days. There were 10 specimens in the test group (n). The shear bond strengths were calculated and expressed in MPa. Data were analyzed statistically, and variations in bond strength within each group were additionally evaluated by calculating the Weibull modulus. Shear bond values of those composites are influenced by the different bonding resins and different indirect composites. There was a significant difference in the shear bond strengths using different types of adhesive resins (p = 0.02) and using different veneering composites (p < 0.01). Belle-Glass® had the highest mean shear bond strength when bonded to StickNet substrate using both Prime & Bond NT and OptiBond Solo Plus. Sinfony® composite resin exhibited the lowest shear bond strength values when used with the same adhesive resins. The adhesive mode of failure was higher than cohesive with all laboratory composite resins bonded to the StickNet substructure at both storage times. Water storage had a tendency to lower the bond strengths of all laboratory composites, although the statistical differences were not significant. Within the limitations of this study, it was found that bonding of the veneering composite to bidirectional continuous fiber-reinforced substrate is influenced by the brand of the adhesive resin and veneering composite. © 2015 by the American College of Prosthodontists.

  17. Marginal behaviour of self-etch adhesive/composite and combined amalgam-composite restorations.

    PubMed

    Kournetas, Nikos; Kakaboura, Afrodite; Giftopoulos, Dimitrios; Chakmachi, Magdad; Rahiotis, Christos; Geis-Gerstorfer, J

    2010-06-01

    The aim of this study was to compare the marginal and internal adaptation in self-etching adhesive (SEA)/composite restorations with combined amalgam-resin-based composite restorations in the proximal box with and without bonding agent beneath amalgam both before and after load-cycling. Class II restorations, were manufactured as following a) Bonding agent (Clearfil Liner Bond 2V, Kuraray) beneath amalgam (Tytin, SDS Kerr) and resin-based composite (Clearfil APX, Kuraray) with SEA, b) Amalgam without bonding agent and resin-based composite with SEA and c) Resin-based composite with SEA. Each group divided into two equal subgroups (n=8). Marginal and internal adaptation of first subgroup evaluated after 7-day water storage and of the second after load-cycling in chewing simulator for 1.2 x 10(6) cycles. Marginal and internal adaptation at cervical and amalgam-composite sites evaluated by videomicroscope and ranked as "excellent"/"non-excellent". Slices of restorations examined under optical microscope to determine the quality of bonding layer. Defects in cervical adaptation observed in the three restorative techniques examined prior loading. Amalgam-composite combination in proximal surface provided comparable marginal and internal adaptation results at cervical wall, to self-etching-composite combination. Portion (25-37.5%) of amalgam-resin-based composite interfaces in proximal box presented no perfect sealing. The application of bonding agent beneath amalgam resulted in relatively inferior cervical adaptation. Loading resulted in fewer excellent restorations in all three restorative techniques but not in a statistically significant level.

  18. Rubicon swaps autophagy for LAP.

    PubMed

    Boyle, Keith B; Randow, Felix

    2015-07-01

    Phagocytic cells engulf their prey into vesicular structures called phagosomes, of which a certain proportion becomes demarcated for enhanced maturation by a process called LC3-associated phagocytosis (LAP). Light has now been shed on the molecular requirements of LAP, establishing a central role for the protein Rubicon in the immune response to Aspergillus fumigatus.

  19. LAP: the protector against autoimmunity.

    PubMed

    Bandyopadhyay, Urmi; Overholtzer, Michael

    2016-08-01

    The autophagy-related process LC3-Associated Phagocytosis, or LAP, is known to control the degradation of engulfed cells and microorganisms. Now Martinez et al. discover that LAP controls immune responses to dying cells and its inhibition leads to development of Systemic Lupus Erythematosus-like disease.

  20. Fracture surface analysis in composite and titanium bonding: Part 1: Titanium bonding

    NASA Technical Reports Server (NTRS)

    Sanderson, K. A.; Wightman, J. P.

    1985-01-01

    Fractured lap shear Ti 6-4 adherends bonded with polyphenyquinoxaline (PPQ) and polysulfone were analyzed. The effects of adherend pretreatment, stress level, thermal aging, anodizing voltage, and modified adhesive of Ti 6-4 adherend bonded with PPQ on lap shear strength were studied. The effect of adherend pretreatment on lap shear strength was investigated for PS samples. Results of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) used to study the surface topography and surface composition are also discussed.

  1. A study of failure in bonded lap joints using fracture mechanics

    NASA Astrophysics Data System (ADS)

    Qian, Haiyang

    Although adhesively bonded lap joint has already been widely applied in structures, the strength prediction of the joint is still a challenge. Among many parameters which affect the failure load of the lap joint, the adhesive layer thickness is a very important one. In this study, fracture mechanics is used to analyze the failure mechanism of the lap joint and evaluate the thickness effect on strength of the lap joint. Generally, the adhesive material is softer than the substrates and the crack in the adhesive layer is constrained by the rigid boundaries. The stress field is changed due to the effect of the rigid boundaries. For linear elastic material, the K-Dominance zone is highly reduced and the traditional constant stress intensity factor prediction over-predicts the failure load of the specimens. Constant effective fracture toughness is proposed for better strength prediction by considering of the non-singular stress term ahead of the crack tip. For elastic-plastic material, CTOA is proven to be insensitive to the constraining of the rigid boundaries and can be used as the failure criterion for fracture analysis. Both experimental and FEA simulation show that constant CTOA criterion well predicts the adhesive thickness effect on strength of the DCB specimens for mode I fracture failure. The failure initiation mode of single lap joint is analyzed and the constant CTOA criterion is also proven to be capable to prediction the strength of single lap joint.

  2. Lap belt injuries in children.

    PubMed

    McGrath, N; Fitzpatrick, P; Okafor, I; Ryan, S; Hensey, O; Nicholson, A J

    2010-01-01

    The use of adult seat belts without booster seats in young children may lead to severe abdominal, lumbar or cervical spine and head and neck injuries. We describe four characteristic cases of lap belt injuries presenting to a tertiary children's hospital over the past year in addition to a review of the current literature. These four cases of spinal cord injury, resulting in significant long-term morbidity in the two survivors and death in one child, arose as a result of lap belt injury. These complex injuries are caused by rapid deceleration characteristic of high impact crashes, resulting in sudden flexion of the upper body around the fixed lap belt, and consequent compression of the abdominal viscera between the lap belt and spine. This report highlights the dangers of using lap belts only without shoulder straps. Age-appropriate child restraint in cars will prevent these injuries.

  3. Effect of thermal shock loadings on stability of dentin-composite polymer material adhesive interfaces

    NASA Astrophysics Data System (ADS)

    Bessudnova, Nadezda O.; Shlyapnikova, Olga A.; Venig, Sergey B.; Gribov, Andrey N.

    2015-03-01

    In the past several decades the problem of longevity and durability of adhesive interfaces between hard tooth tissues and composite resin-based materials are of great interest among dental researchers and clinicians. These parameters are partially determined by adhesive system mechanical properties. In the present research project nanoindentation has been examined to test hardness of dental adhesive systems. A series of laboratory experiments was performed to study the effect of light curing time and oxygen inhibition phenomenon on light-cured adhesive material hardness. An adhesive system AdperTM Single Bond (3M ESPE) was selected as a material for testing. The analysis of experimental data revealed that the maximum values of hardness were observed after the material had been light-cured for 20 seconds, as outlined in guidelines for polymerization time of the adhesive system. The experimental studies of oxygen inhibition influence on adhesive system hardness pointed out to the fact that the dispersive layer removal led to increase in adhesive system hardness. A long - time exposure of polymerized material of adhesive system at open air at room temperature resulted in no changes in its hardness, which was likely to be determined by the mutual effect of rival processes of air oxygen inhibition and directed light curing.

  4. In vitro study of Streptococcus mutans adhesion on composite resin coated with three surface sealants.

    PubMed

    Kim, Da Hye; Kwon, Tae-Yub

    2017-02-01

    Although the coating of surface sealants to dental composite resin may potentially reduce bacterial adhesion, there seems to be little information regarding this issue. This preliminary in vitro study investigated the adhesion of Streptococcus mutans (S. mutans) on the dental composite resins coated with three commercial surface sealants. Composite resin (Filtek Z250) discs (8 mm in diameter, 1 mm in thickness) were fabricated in a mold covered with a Mylar strip (control). In group PoGo, the surfaces were polished with PoGo. In groups PS, OG, and FP, the surfaces polished with PoGo were coated with the corresponding surface sealants (PermaSeal, PS; OptiGuard, OG; Fortify Plus, FP). The surfaces of the materials and S. mutans cells were characterized by various methods. S. mutans adhesion to the surfaces was quantitatively evaluated using flow cytometry (n = 9). Group OG achieved the lowest water contact angle among all groups tested (p < 0.001). The cell surface of S. mutans tested showed hydrophobic characteristics. Group PoGo exhibited the greatest bacterial adhesion among all groups tested (p < 0.001). The sealant-coated groups showed statistically similar (groups PS and FP, p > 0.05) or significantly lower (group OG, p < 0.001) bacterial adhesion when compared with the control group. The application of the surface sealants significantly reduced S. mutans adhesion to the composite resin polished with the PoGo.

  5. Effect of interfacial chemical bonding and surface topography on adhesion in carbon fiber/epoxy composites

    SciTech Connect

    Drzal, L.T.; Sugiura, N.; Hook, D. |

    1994-12-31

    A series of PAN-based IM6 carbon fibers having varying amounts of surface treatment were, pretreated with compounds representing the constituents encountered in epoxy composites to pre-react any groups on the fiber surface before composite fabrication in order to determine the effect of chemical bonding on fiber-matrix adhesion. Chemical bonding was quantified using XPS. Chemical bonding between reactive groups in amine cured epoxy matrices and the surface groups present on IN46 carbon fibers as a result of commercial surface treatments has been detected although the absolute amount of chemical bonding is low (1-3%). It was found that reaction with monofunctional epoxy groups having hydrocarbon functionalities blocked the surface from further reaction and reduced the adhesion that could be attained to its lowest value. Prereaction with difunctional amines had little effect on adhesion when compared to normal composite fabrication procedures. Prereaction with difunctional epoxy groups did enhance adhesion levels over the level attained in normal composite fabrication methods. These results showed that chemical bonding between epoxy and the carbon fiber surface could increases the adhesion between fiber and matrix about 25% while between the amino group and the carbon fiber surface about 15%. Quantitative measurements of the fiber surface microtopography were made with scanning tunneling microscopy. An increase in roughness was detected with increasing surface treatment. It was concluded that surface roughness also accounted for a significant increase in fiber-matrix adhesion.

  6. In vitro study of Streptococcus mutans adhesion on composite resin coated with three surface sealants

    PubMed Central

    Kim, Da Hye

    2017-01-01

    Objectives Although the coating of surface sealants to dental composite resin may potentially reduce bacterial adhesion, there seems to be little information regarding this issue. This preliminary in vitro study investigated the adhesion of Streptococcus mutans (S. mutans) on the dental composite resins coated with three commercial surface sealants. Materials and Methods Composite resin (Filtek Z250) discs (8 mm in diameter, 1 mm in thickness) were fabricated in a mold covered with a Mylar strip (control). In group PoGo, the surfaces were polished with PoGo. In groups PS, OG, and FP, the surfaces polished with PoGo were coated with the corresponding surface sealants (PermaSeal, PS; OptiGuard, OG; Fortify Plus, FP). The surfaces of the materials and S. mutans cells were characterized by various methods. S. mutans adhesion to the surfaces was quantitatively evaluated using flow cytometry (n = 9). Results Group OG achieved the lowest water contact angle among all groups tested (p < 0.001). The cell surface of S. mutans tested showed hydrophobic characteristics. Group PoGo exhibited the greatest bacterial adhesion among all groups tested (p < 0.001). The sealant-coated groups showed statistically similar (groups PS and FP, p > 0.05) or significantly lower (group OG, p < 0.001) bacterial adhesion when compared with the control group. Conclusions The application of the surface sealants significantly reduced S. mutans adhesion to the composite resin polished with the PoGo. PMID:28194363

  7. Compositional design and optimization of dentin adhesive with neutralization capability.

    PubMed

    Song, Linyong; Ye, Qiang; Ge, Xueping; Spencer, Paulette

    2015-09-01

    The objective of this work was to investigate the polymerization behavior, neutralization capability, and mechanical properties of dentin adhesive formulations with the addition of the tertiary amine co-monomer, 2-N-morpholinoethyl methacrylate (MEMA). A co-monomer mixture based on HEMA/BisGMA (45/55, w/w) was used as a control adhesive. Compared with the control formulation, the MEMA-containing adhesive formulations were characterized comprehensively with regard to water miscibility of liquid resin, water sorption and solubility of cured polymer, real-time photopolymerization kinetics, dynamic mechanical analysis (DMA), and modulated differential scanning calorimetry (MDSC). The neutralization capacity was characterized by monitoring the pH shift of 1mM lactic acid (LA) solution, in which the adhesive polymers were soaked. With increasing MEMA concentrations, experimental copolymers showed higher water sorption, lower glass transition temperature and lower crosslinking density compared to the control. The pH values of LA solution gradually increased from 3.5 to about 6.0-6.5 after 90 days. With the increase in crosslinking density of the copolymers, the neutralization rate was depressed. The optimal MEMA concentration was between 20 and 40 wt%. As compared to the control, the results indicated that the MEMA-functionalized copolymer showed neutralization capability. The crosslinking density of the copolymer networks influenced the neutralization rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Compositional design and optimization of dentin adhesive with neutralization capability

    PubMed Central

    Song, Linyong; Ye, Qiang; Ge, Xueping; Spencer, Paulette

    2015-01-01

    Objectives The objective of this work was to investigate the polymerization behavior, neutralization capability, and mechanical properties of dentin adhesive formulations with the addition of the tertiary amine co-monomer, 2-N-morpholinoethyl methacrylate (MEMA). Methods A co-monomer mixture based on HEMA/BisGMA (45/55, w/w) was used as a control adhesive. Compared with the control formulation, the MEMA-containing adhesive formulations were characterized comprehensively with regard to water miscibility of liquid resin, water sorption and solubility of cured polymer, real-time photopolymerization kinetics, dynamic mechanical analysis (DMA), and modulated differential scanning calorimetry (MDSC). The neutralization capacity was characterized by monitoring the pH shift of 1 mM lactic acid (LA) solution, in which the adhesive polymers were soaked. Results With increasing MEMA concentrations, experimental copolymers showed higher water sorption, lower glass transition temperature and lower crosslinking density compared to the control. The pH values of LA solution gradually increased from 3.5 to about 6.0–6.5 after 90 days. With the increase in crosslinking density of the copolymers, the neutralization rate was depressed. The optimal MEMA concentration was between 20 and 40 wt%. Conclusions As compared to the control, the results indicated that the MEMA-functionalized copolymer showed neutralization capability. The crosslinking density of the copolymer networks influenced the neutralization rate. PMID:26144189

  9. Preliminary evaluation of adhesion strength measurement devices for ceramic/titanium matrix composite bonds

    NASA Technical Reports Server (NTRS)

    Pohlchuck, Bobby; Zeller, Mary V.

    1992-01-01

    The adhesive bond between ceramic cement and a titanium matrix composite substrate to be used in the National Aerospace Plane program is evaluated. Two commercially available adhesion testers, the Sebastian Adherence Tester and the CSEM REVETEST Scratch Tester, are evaluated to determine their suitability for quantitatively measuring adhesion strength. Various thicknesses of cements are applied to several substrates, and bond strengths are determined with both testers. The Sabastian Adherence Tester has provided limited data due to an interference from the sample mounting procedure, and has been shown to be incapable of distinguishing adhesion strength from tensile and shear properties of the cement itself. The data from the scratch tester has been found to be difficult to interpret due to the porosity and hardness of the cement. Recommendations are proposed for a more reliable adhesion test method.

  10. A phenomenological model of coating/substrate adhesion and interfacial bimetallic peeling stress in composite mirrors

    NASA Technical Reports Server (NTRS)

    Mcelroy, Paul M.; Lawson, Daniel D.

    1990-01-01

    Adhesion and interfacial stress between metal films and structural composite material substrates is discussed. A theoretical and conceptual basis for selecting coating materials for composite mirror substrates is described. A phenomenological model that interrelates cohesive tensile strength of thin film coatings and interfacial peeling stresses is presented. The model serves as a basis in determining gradiated materials response and compatibility of composite substrate and coating combinations. Parametric evaluation of material properties and geometrical factors such as coating thickness are used to determine the threshold stress levels for maintaining adhesion at the different interfaces.

  11. Single anterior tooth restoration using a self-etching adhesive system and a reinforced microfill composite.

    PubMed

    Feigenbaum, Norman

    2003-08-01

    Treatment for a single discolored anterior tooth may involve placement of a direct composite veneer to enhance a patient's smile and mask underlying discoloration. Among the challenges clinicians may face in this endeavor are the selection of suitable composite materials, application of an adhesive bonding system, and re-creation of the natural shade variations inherent in natural teeth. This article discusses the characteristics and placement protocol for a recently introduced self-etching adhesive system and a reinforced microfill composite when they are used to restore a single discolored central incisor.

  12. A phenomenological model of coating/substrate adhesion and interfacial bimetallic peeling stress in composite mirrors

    NASA Technical Reports Server (NTRS)

    Mcelroy, Paul M.; Lawson, Daniel D.

    1990-01-01

    Adhesion and interfacial stress between metal films and structural composite material substrates is discussed. A theoretical and conceptual basis for selecting coating materials for composite mirror substrates is described. A phenomenological model that interrelates cohesive tensile strength of thin film coatings and interfacial peeling stresses is presented. The model serves as a basis in determining gradiated materials response and compatibility of composite substrate and coating combinations. Parametric evaluation of material properties and geometrical factors such as coating thickness are used to determine the threshold stress levels for maintaining adhesion at the different interfaces.

  13. Effect of new adhesion promoter and mechanical interlocking on bonding strength in metal-polymer composites

    NASA Astrophysics Data System (ADS)

    Schuberth, A.; Göring, M.; Lindner, T.; Töberling, G.; Puschmann, M.; Riedel, F.; Scharf, I.; Schreiter, K.; Spange, S.; Lampke, T.

    2016-03-01

    There are various opportunities to improve the adhesion between polymer and metal in metal-plastic composites. The addition of a bonding agent which reacts with both joining components at the interfaces of the composite can enhance the bonding strength. An alternative method for the adjustment of interfaces in metal-plastic composites is the specific surface structuring of the joining partners in order to exploit the mechanical interlock effect. In this study the potential of using an adhesion promoter based on twin polymerization for metal-plastic composites in combination with different methods of mechanical surface treatment is evaluated by using the tensile shear test. It is shown that the new adhesion promoter has a major effect when applied on smooth metal surfaces. A combination of both mechanical and chemical surface treatment of the metal part is mostly just as effective as the application of only one of these surface treatment methods.

  14. Film/Adhesive Processing Module for Fiber-Placement Processing of Composites

    NASA Technical Reports Server (NTRS)

    Hulcher, A. Bruce

    2007-01-01

    An automated apparatus has been designed and constructed that enables the automated lay-up of composite structures incorporating films, foils, and adhesives during the automated fiber-placement process. This apparatus, denoted a film module, could be used to deposit materials in film or thin sheet form either simultaneously when laying down the fiber composite article or in an independent step.

  15. Deformations and strains in a thick adherend lap joint

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Wood, J. D.; Joh, D.

    1988-01-01

    Displacement fields in a thick adherend lap joint were measured by high-sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherend surfaces. Loads ranged from a modest load to a near-failure load. Quantitative results are given for displacements and strains in the adhesive and along the adhesive/adherend boundary lines. The results show nearly constant shear strain in the adhesive, nonlinear strains as a function of load or average shear stress, and viscoelastic or time-dependent response. Longitudinal normal strains in the adhesive are nearly two orders of magnitude less than the shear strains. With its subwavelength displacement resolution and high spatial resolution, moire interferometry is especially well suited for deformation studies of adhesive joints.

  16. Flexibilized copolyimide adhesives

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.; St.clair, Terry L.

    1988-01-01

    Two copolyimides, LARC-STPI and STPI-LARC-2, with flexible backbones were processed and characterized as adhesives. The processability and adhesive properties were compared to those of a commercially available form of LARC-TPI. Lap shear specimens were fabricated using adhesive tape prepared from each of the three polymers. Lap shear tests were performed at room temperature, 177 C, and 204 C before and after exposure to water-boil and to thermal aging at 204 C for up to 1000 hours. The three adhesive systems possess exceptional lap shear strengths at room temperature and elevated temperatures both before and after thermal exposure. LARC-STPI, because of its high glass transition temperature provided high lap shear strengths up to 260 C. After water-boil, LARC-TPI exhibited the highest lap shear strengths at room temperature and 177 C, whereas the LARC-STPI retained a higher percentage of its original strength when tested at 204 C. These flexible thermoplastic copolyimides show considerable potential as adhesives based on this study and because of the ease of preparation with low cost, commercially available materials.

  17. Effect of laser preparation on adhesion of a self-adhesive flowable composite resin to primary teeth.

    PubMed

    Memarpour, Mahtab; Shafiei, Fereshteh; Razmjoei, Faranak; Kianimanesh, Nasrin

    2016-04-01

    The aim of the study was to evaluate the adhesion of a self-adhering flowable composite resin to primary tooth enamel and dentin after silicon carbide paper (SiC) and laser pretreatment. Adhesive properties were evaluated as shear bond strength (SBS) and scanning electron microscopic (SEM) characteristics. A total 120 primary canine teeth were randomly divided into two groups to study enamel and dentin. Each group was divided into 6 subgroups (n = 10) according to type of surface preparation (SiC or Er:YAG laser) of enamel or dentin. Three methods were used to build cylinders of restoration on tooth surface: OptiBond All-In-One + Premise Flowable composite, OptiBond All-In-One + Vertise Flow and Vertise flow. After restoration, samples were tested for SBS and failure mode. Twenty eight samples were examined by SEM. The results of the study showed SBS of Vertise Flow was lower than others in enamel and dentin samples pretreated with SiC and in dentin samples pretreated with laser (P < 0.001). Compared to SiC pretreatment, laser pretreatment led to a significantly higher SBS with Vertise Flow on enamel (P < 0.001). Vertise Flow associated with the adhesive led to a higher SBS in enamel and dentin compared to Vertise Flow alone. Adhesive and mixed failure modes were observed more frequently in Vertise Flow groups. SEM images showed that Vertise Flow led to more irregularities on enamel and more open dentinal tubules after laser ablation compared SiC pretreatment.

  18. Effects of modifying the adhesive composition on the bond strength of orthodontic brackets.

    PubMed

    Bishara, Samir E; Ajlouni, Raed; Laffoon, John; Warren, John

    2002-10-01

    In an attempt to save chair time during bonding, metal brackets have been precoated with the adhesive material. Although the adhesive used on the precoated brackets is basically similar in composition to that used for bonding uncoated brackets, there are differences in the percentages of the various ingredients incorporated in the material. These changes are intended to enhance specific clinical properties. The purpose of this study was to determine whether modifications in the composition of the adhesives, used on precoated and uncoated metal brackets, affect their shear bond strengths during the first half hour after bonding. This is the time span when the initial arch wires are ligated. Sixty freshly extracted human molars were bonded with three different compositions of the same basic adhesive. The teeth were mounted in phenolic rings. An occlusogingival load was applied to the brackets producing a shear force at the bracket-tooth interface utilizing a Zwick Universal Test Machine. Analysis of variance was used to compare the three adhesives. Significance was predetermined at < or =.05 level of confidence. The present findings indicated that the shear bond strengths of the various modifications of the adhesive used on two different precoated metal brackets were not significantly different (F-ratio = .729 and P = .407) from those obtained with the conventional adhesive used on uncoated brackets. The mean values for the shear bond strengths of the two precoated brackets were: APC = 5.1+/-1.7 MPa and APC II = 4.9+/-2.1 MPa. The shear bond strength for the conventional adhesive used on the uncoated brackets was = 5.7+/-2.4 MPa. All bracket/adhesive combinations tested provided clinically acceptable shear bond forces within the first 30 minutes after initial bonding.

  19. Rapid adhesive bonding concepts

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

    1984-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

  20. Does the use of a novel self-adhesive flowable composite reduce nanoleakage?

    PubMed Central

    Naga, Abeer Abo El; Yousef, Mohammed; Ramadan, Rasha; Fayez Bahgat, Sherif; Alshawwa, Lana

    2015-01-01

    Objective The aim of the study reported here was to evaluate the performance of a self-adhesive flowable composite and two self-etching adhesive systems, when subjected to cyclic loading, in preventing the nanoleakage of Class V restorations. Methods Wedge-shape Class V cavities were prepared (4×2×2 mm [length × width × depth]) on the buccal surfaces of 90 sound human premolars. Cavities were divided randomly into three groups (n=30) according to the used adhesive (Xeno® V [self-etching adhesive system]) and BOND-1® SF (solvent-free self-etching adhesive system) in conjunction with Artiste® Nano Composite resin, and Fusio™ Liquid Dentin (self-adhesive flowable composite), consecutively. Each group was further divided into three subgroups (n=10): (A) control, (B) subjected to occlusal cyclic loading (90N for 5,000 cycles), and (C) subjected to occlusal cyclic loading (90N for 10,000 cycles). Teeth then were coated with nail polish up to 1 mm from the interface, immersed in 50% silver nitrate solution for 24 hours and tested for nanoleakage using the environmental scanning electron microscopy and energy dispersive analysis X-ray analysis. Data were statistically analyzed using two-way analysis of variance and Tukey’s post hoc tests (P≤0.05). Results The Fusio Liquid Dentin group showed statistically significant lower percentages of silver penetration (0.55 μ) compared with the BOND-1 SF (3.45 μ) and Xeno V (3.82 μ) groups, which were not statistically different from each other, as they both showed higher silver penetration. Conclusion Under the test conditions, the self-adhesive flowable composite provided better sealing ability. Aging of the two tested adhesive systems, as a function of cyclic loading, increased nanoleakage. PMID:25848318

  1. [Dentin bonding with tooth-colored adhesive MOD immediate inlays made of composites].

    PubMed

    Krejci, I; Picco, U; Lutz, F

    1990-01-01

    Without the use of highly effective dentinal adhesives, the cervical margins of tooth-colored adhesive inlays localized in dentin are poorly adapted. It was the purpose of this study to optimize these margins with the help of the Gluma-Clearfil combination. This goal was achieved, but the results indicated, that the success depended on the choice of the luting composite. Perfectly adapted cervical dentinal margins of tooth-colored adhesive inlays are achievable. For routine use, the system has to be simplified.

  2. Adhesion to root canal dentine using one and two-step adhesives with dual-cure composite core materials.

    PubMed

    Foxton, R M; Nakajima, M; Tagami, J; Miura, H

    2005-02-01

    The regional tensile bond strengths of two dual-cure composite resin core materials to root canal dentine using either a one or two-step self-etching adhesive were evaluated. Extracted premolar teeth were decoronated and their root canals prepared to a depth of 8 mm and a width of 1.4 mm. In one group, a one-step self-etching adhesive (Unifil Self-etching Bond) was applied to the walls of the post-space and light-cured for 10 s. After which, the post-spaces were filled with the a dual-cure composite resin (Unifil Core) and then half the specimens were light-cured for 60 s and the other half placed in darkness for 30 min. In the second group, a self-etching primer (ED Primer II) was applied for 30 s, followed by an adhesive resin (Clearfil Photo Bond), which was light-cured for 10 s. The post-spaces were filled with a dual-cure composite resin (DC Core) and then half the specimens were light-cured for 60 s and the other half placed in darkness for 30 min. Chemical-cure composite resin was placed on the outer surfaces of all the roots, which were then stored in water for 24 h. They were serially sliced perpendicular to the bonded interface into 8, 0.6 mm-thick slabs, and then transversely sectioned into beams, approximately 8 x 0.6 x 0.6 mm, for the microtensile bond strength test (muTBS). Data were divided into two (coronal/apical half of post-space) and analysed using three-way anova and Scheffe's test (P < 0.05). Failure modes were observed under an scanning electron microscope (SEM) and statistically analysed. Specimens for observation of the bonded interfaces were prepared in a similar manner as for bond strength testing, cut in half and embedded in epoxy resin. They were then polished to a high gloss, gold sputter coated, and after argon ion etching, observed under an SEM. For both dual-cure composite resins and curing strategies, there were no significant differences in muTBS between the coronal and apical regions (P > 0.05). In addition, both dual

  3. Relationship between mechanical properties and bond durability of short fiber-reinforced resin composite with universal adhesive.

    PubMed

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2016-10-01

    The purpose of this study was to determine the relationship between mechanical properties and bond durability of short fiber-reinforced resin composite with universal adhesive. As controls, micro-hybrid and nano-hybrid resin composites were tested. The universal adhesives used were Scotchbond Universal, Adhese Universal, and G-Premio Bond. The fracture toughness and flexural properties of resin composites, and shear bond strength and shear fatigue strength of universal adhesive with resin composite using both total-etch and self-etch modes were determined. In the results, short fiber-reinforced resin composite showed significantly higher fracture toughness than did micro-hybrid and nano-hybrid resin composites. The flexural strength and modulus of short fiber-reinforced and nano-hybrid resin composites were significantly lower than were those of micro-hybrid resin composites. Regardless of etching mode, the shear bond strength of universal adhesives with short fiber-reinforced resin composite did not show any significant differences from micro-hybrid and nano-hybrid resin composites. The shear fatigue strength of universal adhesives with short fiber-reinforced resin composite and micro-hybrid resin composites were significantly higher than that of nano-hybrid resin composites. The results of this study suggest that the mechanical properties of short fiber-reinforced resin composite improve their bond durability with universal adhesive. © 2016 Eur J Oral Sci.

  4. High Performance Composites and Adhesives for V/STOL Aircraft.

    DTIC Science & Technology

    1984-02-22

    methylene protons adjacent to the carbonyl group of sebacic acid . be exp The presence of these compounds in the C.-.-diamide/SnCl- mixture can lained by...adhesive evaluations. Fig. 1 gives the schematic of the specimen geometry. The adherends were 5086 aluminum alloy, cleaned by acid -chromate etching...minutes. At this stage, the material remains sufficiently fluid for proper prepregging. Further heating may increase the melt viscosity beyond the

  5. Influence of artificial ageing on surface properties and Streptococcus mutans adhesion to dental composite materials.

    PubMed

    Hahnel, Sebastian; Henrich, Anne; Rosentritt, Martin; Handel, Gerhard; Bürgers, Ralf

    2010-02-01

    The aim of this in vitro study was to investigate the influence of artificial ageing on the surface properties and early Streptococcus mutans adhesion to current dental composites for the direct restoration of class II defects. Three hundred and thirty specimens each were prepared from five dental composites, and were randomly allotted to various artificial ageing protocols (storage in distilled water/ethanol/artificial saliva for 7/90/365 days; thermal cycling, 6,000 cycles 5/55 degrees C). Prior and after each treatment, surface roughness (R(a)) and hydrophobicity were determined, and S. mutans adhesion (ATCC 25175; 2.5 h, 37 degrees C) was simulated with and without prior exposition to human whole saliva (2 h, 37 degrees C). Adherence of S. mutans was determined fluorometrically. Means and standard deviations were calculated, and analyzed using three-way ANOVA and post-hoc analysis (alpha = 0.05). For both R(a) and S. mutans adherence to uncoated and saliva-coated specimens, significant influences of the composite material, the ageing medium and the ageing duration have been observed; for surface hydrophobicity, significant influences of the composite material and the ageing duration were found. For uncoated specimens, significant increases in S. mutans adhesion were observed with prolonged artificial ageing, whereas significant decreases in S. mutans adhesion were found for the saliva-coated specimens. The data indicate influences of the artificial ageing method on surface parameters such as R(a) and hydrophobicity as well as microbial adhesion. The results underline the relevance of saliva coating on the outcome of studies simulating microbial adhesion, and highlight differences in the susceptibility of dental composites for the adhesion of oral bacteria.

  6. Reducing composite restoration polymerization shrinkage stress through resin modified glass-ionomer based adhesives.

    PubMed

    Naoum, S J; Mutzelburg, P R; Shumack, T G; Thode, Djg; Martin, F E; Ellakwa, A E

    2015-12-01

    The aim of this study was to determine whether employing resin modified glass-ionomer based adhesives can reduce polymerization contraction stress generated at the interface of restorative composite adhesive systems. Five resin based adhesives (G Bond, Optibond-All-in-One, Optibond-Solo, Optibond-XTR and Scotchbond-Universal) and two resin modified glass-ionomer based adhesives (Riva Bond-LC, Fuji Bond-LC) were analysed. Each adhesive was applied to bond restorative composite Filtek-Z250 to opposing acrylic rods secured within a universal testing machine. Stress developed at the interface of each adhesive-restorative composite system (n = 5) was calculated at 5-minute intervals over 6 hours. The resin based adhesive-restorative composite systems (RBA-RCS) demonstrated similar interface stress profiles over 6 hours; initial rapid contraction stress development (0-300 seconds) followed by continued contraction stress development ≤0.02MPa/s (300 seconds - 6 hours). The interface stress profile of the resin modified glass-ionomer based adhesive-restorative composite systems (RMGIBA-RCS) differed substantially to the RBA-RCS in several ways. Firstly, during 0-300 seconds the rate of contraction stress development at the interface of the RMGIBA-RCS was significantly (p < 0.05) lower than at the interface of the RBA-RCS. Secondly, at 300 seconds and 6 hours the interface contraction stress magnitude of the RMGIBA-RCS was significantly (p < 0.05) lower than the stress of all assessed RBA-RCS. Thirdly, from 300 seconds to 6 hours both the magnitude and rate of interface stress of the RMGIBA-RCS continued to decline over the 6 hours from the 300 seconds peak. The use of resin modified glass-ionomer based adhesives can significantly reduce the magnitude and rate of polymerization contraction stress developed at the interface of adhesive-restorative composite systems. © 2015 Australian Dental Association.

  7. Nanotechnology strategies for antibacterial and remineralizing composites and adhesives to tackle dental caries

    PubMed Central

    Cheng, Lei; Zhang, Ke; Weir, Michael D; Melo, Mary Anne S; Zhou, Xuedong; Xu, Hockin HK

    2015-01-01

    Dental caries is the most widespread disease and an economic burden. Nanotechnology is promising to inhibit caries by controlling biofilm acids and enhancing remineralization. Nanoparticles of silver were incorporated into composites/adhesives, along with quaternary ammonium methacrylates (QAMs), to combat biofilms. Nanoparticles of amorphous calcium phosphate (NACP) released calcium/phosphate ions, remineralized tooth-lesions and neutralized acids. By combining NAg/QAM/NACP, a new class of composites and adhesives with antibacterial and remineralization double benefits was developed. Various other nanoparticles including metal and oxide nanoparticles such as ZnO and TiO2, as well as polyethylenimine nanoparticles and their antibacterial capabilities in dental resins were also reviewed. These nanoparticles are promising for incorporation into dental composites/cements/sealants/bases/liners/adhesives. Therefore, nanotechnology has potential to significantly improve restorative and preventive dentistry. PMID:25723095

  8. Nanotechnology strategies for antibacterial and remineralizing composites and adhesives to tackle dental caries.

    PubMed

    Cheng, Lei; Zhang, Ke; Weir, Michael D; Melo, Mary Anne S; Zhou, Xuedong; Xu, Hockin H K

    2015-03-01

    Dental caries is the most widespread disease and an economic burden. Nanotechnology is promising to inhibit caries by controlling biofilm acids and enhancing remineralization. Nanoparticles of silver were incorporated into composites/adhesives, along with quaternary ammonium methacrylates (QAMs), to combat biofilms. Nanoparticles of amorphous calcium phosphate (NACP) released calcium/phosphate ions, remineralized tooth-lesions and neutralized acids. By combining nanoparticles of silver/QAM/NACP, a new class of composites and adhesives with antibacterial and remineralization double benefits was developed. Various other nanoparticles including metal and oxide nanoparticles such as ZnO and TiO2, as well as polyethylenimine nanoparticles and their antibacterial capabilities in dental resins were also reviewed. These nanoparticles are promising for incorporation into dental composites/cements/sealants/bases/liners/adhesives. Therefore, nanotechnology has potential to significantly improve restorative and preventive dentistry.

  9. Shear bond strengths produced by composite and compomer light cured orthodontic adhesives.

    PubMed

    Rock, W P; Abdullah, M S

    1997-01-01

    To test the shear bond strengths obtained when orthodontic brackets were bonded ex vivo using a composite resin and a compomer orthodontic adhesive. Specimens were tested in a special jig made to fit an Instron testing machine. After debonding, the adhesive remaining on bracket bases and enamel surfaces was mapped. Bond strengths ranged from 8 to 23 MPa with the composite resin producing higher strengths than the compomer for similar combinations of variables. Bond strength was increased by longer curing and a longer debond interval and was higher for brackets with mesh bases than undercut bases. More compomer remained on the enamel surface after debonding than did the composite resin. The compomer produced bond strengths within the range considered to be clinically acceptable in other studies. If it was clinically successful as an orthodontic adhesive a compomer would confer the advantage that fluoride release would help to minimize the onset of early caries around bonded brackets.

  10. Effect of indirect composite treatment microtensile bond strength of self-adhesive resin cements.

    PubMed

    Fuentes, María-Victoria; Escribano, Nuria; Baracco, Bruno; Romero, Martin; Ceballos, Laura

    2016-02-01

    No specific indications about the pre-treatment of indirect composite restorations is provided by the manufacturers of most self-adhesive resin cements. The potential effect of silane treatment to the bond strength of the complete tooth/indirect restoration complex is not available.The aim of this study was to determine the contribution of different surface treatments on microtensile bond strength of composite overlays to dentin using several self-adhesive resin cements and a total-etch one. Composite overlays were fabricated and bonding surfaces were airborne-particle abraded and randomly assigned to two different surface treatments: no treatment or silane application (RelyX Ceramic Primer) followed by an adhesive (Adper Scotchbond 1 XT). Composite overlays were luted to flat dentin surfaces using the following self-adhesive resin cements: RelyX Unicem, G-Cem, Speedcem, Maxcem Elite or Smartcem2, and the total-etch resin cement RelyX ARC. After 24 h, bonded specimens were cut into sticks 1 mm thick and stressed in tension until failure. Two-way ANOVA and SNK tests were applied at α=0.05. Bond strength values were significantly influenced by the resin cement used (p<0.001). However, composite surface treatment and the interaction between the resin cement applied and surface treatment did not significantly affect dentin bond strength (p>0.05). All self-adhesive resin cements showed lower bond strength values than the total-etch RelyX ARC. Among self-adhesive resin cements, RelyX Unicem and G-Cem attained statistically higher bond strength values. Smartcem2 and Maxcem Elite exhibited 80-90% of pre-test failures. The silane and adhesive application after indirect resin composite sandblasting did not improve the bond strength of dentin-composite overlay complex. Selection of the resin cement seems to be a more relevant factor when bonding indirect composites to dentin than its surface treatment. Bond strength, self-adhesive cement, silane, dentin, indirect composite.

  11. Effect of indirect composite treatment microtensile bond strength of self-adhesive resin cements

    PubMed Central

    Escribano, Nuria; Baracco, Bruno; Romero, Martin; Ceballos, Laura

    2016-01-01

    Background No specific indications about the pre-treatment of indirect composite restorations is provided by the manufacturers of most self-adhesive resin cements. The potential effect of silane treatment to the bond strength of the complete tooth/indirect restoration complex is not available.The aim of this study was to determine the contribution of different surface treatments on microtensile bond strength of composite overlays to dentin using several self-adhesive resin cements and a total-etch one. Material and Methods Composite overlays were fabricated and bonding surfaces were airborne-particle abraded and randomly assigned to two different surface treatments: no treatment or silane application (RelyX Ceramic Primer) followed by an adhesive (Adper Scotchbond 1 XT). Composite overlays were luted to flat dentin surfaces using the following self-adhesive resin cements: RelyX Unicem, G-Cem, Speedcem, Maxcem Elite or Smartcem2, and the total-etch resin cement RelyX ARC. After 24 h, bonded specimens were cut into sticks 1 mm thick and stressed in tension until failure. Two-way ANOVA and SNK tests were applied at α=0.05. Results Bond strength values were significantly influenced by the resin cement used (p<0.001). However, composite surface treatment and the interaction between the resin cement applied and surface treatment did not significantly affect dentin bond strength (p>0.05). All self-adhesive resin cements showed lower bond strength values than the total-etch RelyX ARC. Among self-adhesive resin cements, RelyX Unicem and G-Cem attained statistically higher bond strength values. Smartcem2 and Maxcem Elite exhibited 80-90% of pre-test failures. Conclusions The silane and adhesive application after indirect resin composite sandblasting did not improve the bond strength of dentin-composite overlay complex. Selection of the resin cement seems to be a more relevant factor when bonding indirect composites to dentin than its surface treatment. Key words

  12. Initial adhesion of glass-fiber-reinforced composite to the surface of porcine calvarial bone.

    PubMed

    Tuusa, S M R; Lassila, L V J; Matinlinna, J P; Peltola, M J; Vallittu, P K

    2005-11-01

    The aim of this preliminary study was to compare the initial bond strength of the glass-fiber-reinforced composite veil to the surface of the porcine calvarial compact bone using different adhesives. Fiber-reinforced composite (FRC) made of E-glass fiber veil with the BisGMA-PMMA resin system was used in the study. For the shear bond strength test, porcine calvarial bone cubes were mounted into resin matrix. FRC-veil discs were bonded to compact bone with different types of adhesives: (A) BisGMA-HEMA based (3M-ESPE Scotchbond Multi-Purpose Adhesive), (B) 4-META/UDMA/BisGMA based (Unifil Bond Bonding Agent) and MDP based (Clearfil Se Bond adhesive), (C) UDMA/BisGMA/PMMA-based experimental adhesive, and (D) silane-based (APS, ICS, MPS) experimental adhesives. The surface of the bone was mechanically roughened and was either used as such, treated with dental primers (Unifil Bond Self-etching Primer, Clearfil Se Bond Primer), or treated with an experimental silane mixture (APS, ICS, MPS), or with a mixture of the experimental silane liquid and Clearfil Se Bond Primer. The 3M-ESPE Scotchbond Multi-Purpose Adhesive and UDMA/BisGMA/PMMA experimental adhesive gave poor results in the shear bond test (0.58 and 0.40 MPa, respectively). Unifil Bond Bonding Agent and Clearfil Se Bond adhesive with respective primers markedly improved the shear bond strength; with Unifil the result was 3.40 MPa, and with Clearfil it was 6.19 MPa. When the bone surface was primed with a mixture of Clearfil Se Bond Primer and Clearfil Porcelain Bond Activator, the Clearfil Se Bond adhesive-impregnated FRC veil gave the best adhesion to the bone surface in this test: 9.50 MPa. The addition of bioactive glass granules between the veil and the bone lowered the shear bond strength in the test system described above to 6.72 MPa. The test systems with the silane mixture were also promising. In the SEM study, it was found that the mechanical treatment reveals the pores of the bone surface. Chemical

  13. Adhesion and hemifusion of cytoplasmic myelin lipid membranes are highly dependent on the lipid composition

    PubMed Central

    Banquy, Xavier; Kristiansen, Kai; Lee, Dong Woog; Israelachvili, Jacob N.

    2012-01-01

    We report the effects of calcium ions on the adhesion and hemifusion mechanisms of model supported myelin lipid bilayer membranes of differing lipid composition. As in our previous studies [1, 2], the lipid compositions used mimic “healthy” and “diseased-like” (experimental autoimmune encephalomyelitis, EAE) membranes. Our results show that the interaction forces as a function of membrane separation distance are well described by a generic model that also (and in particular) includes the hydrophobic interaction arising from the hydrophobically exposed (interior) parts of the bilayers. The model is able to capture the mechanical instability that triggers the onset of the hemifusion event, and highlights the primary role of the hydrophobic interaction in membrane fusion. The effects of lipid composition on the fusion mechanism, and the adhesion forces between myelin lipid bilayers, can be summarized as follow: in calcium-free buffer, healthy membranes do not present any signs of adhesion or hemifusion, while diseased membranes hemifuse easily. Addition of 2 mM calcium favors adhesion and hemifusion of the membranes independently of their composition, but the mechanisms involved in the two processes were different: healthy bilayers systematically presented stronger adhesion forces and lower energy barriers to fusion compared to diseased bilayers. These results are of particular relevance for understanding lesion development (demyelination, swelling, vacuolization and/or vesiculation) in myelin associated diseases such as multiple sclerosis and its relationship to lipid domain formation in myelin membranes. PMID:22047743

  14. Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies

    PubMed Central

    Bastos, Laura Alves; Sousa, Ana Beatriz Silva; Drubi-Filho, Brahim; Panzeri Pires-de-Souza, Fernanda de Carvalho

    2015-01-01

    Objectives The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Materials and Methods Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/Silorane and Silorane groups). Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE) were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray), with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups), or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE) (Three-step/Methacrylate group) (n = 6). The restored teeth were sectioned into stick-shaped test specimens (1.0 × 1.0 mm), and coupled to a universal test machine (0.5 mm/min) to perform microtensile testing. Results Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p < 0.05). However, it was not significantly different from Preetching/Silorane and Methacrylate groups. Conclusions Pre-etching increased bond strength of silorane-based composite specific adhesive system to dentin. PMID:25671209

  15. LARC-13 polyimide adhesive bonding

    NASA Technical Reports Server (NTRS)

    Saint Clair, T. L.; Progar, D. J.

    1979-01-01

    The development of an addition-curing polyimide adhesive suitable for low pressure bonding without the generation of volatiles during cure is reported. LARC-13 is designed for bonding of polyimide matrix composites and of titanium to be used above 500 F, and is based on an oligomeric bis-nadimide which allows its processing at 50 psi or less, making it suitable for the bonding of fragile honeycomb sandwich structures. Few volatiles are evolved during its cure allowing large enclosed structures to be bonded, and it has high room and elevated temperature strengths and good strength retention after short terms up to 1100 F. LARC-13 was successfully used to bond the outer and inner skins of a polyimide/graphite wing shear panel for 500 F use, and for a short-term exposure up to 1100 F. Preparation of the adhesive, bonding, aging, and testing of lap shear and honeycomb samples are discussed.

  16. Global-Local Finite Element Analysis of Bonded Single-Lap Joints

    NASA Technical Reports Server (NTRS)

    Kilic, Bahattin; Madenci, Erdogan; Ambur, Damodar R.

    2004-01-01

    Adhesively bonded lap joints involve dissimilar material junctions and sharp changes in geometry, possibly leading to premature failure. Although the finite element method is well suited to model the bonded lap joints, traditional finite elements are incapable of correctly resolving the stress state at junctions of dissimilar materials because of the unbounded nature of the stresses. In order to facilitate the use of bonded lap joints in future structures, this study presents a finite element technique utilizing a global (special) element coupled with traditional elements. The global element includes the singular behavior at the junction of dissimilar materials with or without traction-free surfaces.

  17. Influence of superconductor film composition on adhesion strength of coated conductors

    SciTech Connect

    Kesgin, Ibrahim; Khatri, Narayan; Liu, Yuhao; Delgado, Louis; Galstyan, Eduard; Selvamanickam, Venkat

    2015-11-20

    The effect of high temperature superconductor (HTS) film composition on the adhesion strength of rare- earth barium copper oxide coated conductors (CCs) has been studied. It has been found that the mechanical integrity of the superconductor layer is very susceptible to the defects especially those along the ab plane, probably due to the weak interfaces between the defects and the matrix. Gd and Y in the standard composition were substituted with Sm and the number of in-plane defects was drastically reduced. Consequently, a four-fold increase in adhesion or peeling strength in Sm-based CCs was achieved compared to the standard GdYBCO samples.

  18. Adhesive systems: important aspects related to their composition and clinical use

    PubMed Central

    SILVA E SOUZA JUNIOR, Mario Honorato; CARNEIRO, Karina Gama Kato; LOBATO, Marcelo Figueiredo; SILVA E SOUZA, Patrícia de Almeida Rodrigues; de GÓES, Mário Fernando

    2010-01-01

    This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classified according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-andrinse systems require a specific acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and deficiencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplified ones due to some chemical associations and interactions. The SeM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions. PMID:20856995

  19. Adhesive systems: important aspects related to their composition and clinical use.

    PubMed

    Silva e Souza, Mario Honorato; Carneiro, Karina Gama Kato; Lobato, Marcelo Figueiredo; Silva e Souza, Patrícia de Almeida Rodrigues; de Góes, Mário Fernando

    2010-01-01

    This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classified according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-and-rinse systems require a specific acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and deficiencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplified ones due to some chemical associations and interactions. The SEM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

  20. Materials research for High Speed Civil Transport and generic hypersonics: Adhesive durability

    NASA Technical Reports Server (NTRS)

    Allen, Mark R.

    1995-01-01

    This report covers a portion of an ongoing investigation of the durability of adhesives for the High Speed Civil Transport (HSCT) program. Candidate HSCT adhesives need to possess the high-temperature capability required for supersonic flight. This program was designed to initiate an understanding of the behavior of candidate HSCT materials when subjected to combined mechanical and thermal loads. Two adhesives (K3A and FM57) and two adherends (IM7/K3B polymeric composite and the titanium alloy Ti-6Al-4V) were used to fabricate thick adherend lap shear specimens. Due to processing problems, only the FM57/titanium bonds could be fabricated successfully. These are currently undergoing thermomechanical fatigue (TMF) testing. There is an acute need for an adhesive to secondarily bond polymeric composite adherends or, alternately, polymeric composites that remain stable at the processing temperatures of today's adhesives.

  1. Composite Pillars with a Tunable Interface for Adhesion to Rough Substrates

    PubMed Central

    2016-01-01

    The benefits of synthetic fibrillar dry adhesives for temporary and reversible attachment to hard objects with smooth surfaces have been successfully demonstrated in previous studies. However, surface roughness induces a dramatic reduction in pull-off stresses and necessarily requires revised design concepts. Toward this aim, we introduce cylindrical two-phase single pillars, which are composed of a mechanically stiff stalk and a soft tip layer. Adhesion to smooth and rough substrates is shown to exceed that of conventional pillar structures. The adhesion characteristics can be tuned by varying the thickness of the soft tip layer, the ratio of the Young’s moduli and the curvature of the interface between the two phases. For rough substrates, adhesion values similar to those obtained on smooth substrates were achieved. Our concept of composite pillars overcomes current practical limitations caused by surface roughness and opens up fields of application where roughness is omnipresent. PMID:27997118

  2. Improving adhesion of powder coating on PEEK composite: Influence of atmospheric plasma parameters

    NASA Astrophysics Data System (ADS)

    Dupuis, Aurélie; Ho, Thu Huong; Fahs, Ahmad; Lafabrier, Aurore; Louarn, Guy; Bacharouche, Jalal; Airoudj, Aissam; Aragon, Emmanuel; Chailan, Jean-François

    2015-12-01

    In aeronautic industries, powder coatings are increasingly used because of environmental considerations. During the deposition of such a coating on a substrate piece, the main objective is to obtain a good coating/substrate adhesion. In this study, the targeted substrate is a Poly-(Ether EtherKetone)-(PEEK) based composite material. Due to the poor surface energy of PEEK, a surface treatment is necessary in order to enhance its adhesion with the coating. In this purpose, atmospheric plasma treatment has been chosen and the influence of plasma parameters has been studied. Four scan speed nozzles and three gases (Air, N2 and Argon) plasma has been tested. The increase of adhesion with increasing wettability, polarity and nanoroughness has been evidenced. A particular study of the type of grafted polar functionalities according to gas nature allowed to better understand the plasma mechanism and the cross-impact of polarity and nanoroughness in adhesion enhancement.

  3. Composite Pillars with a Tunable Interface for Adhesion to Rough Substrates.

    PubMed

    Fischer, Sarah C L; Arzt, Eduard; Hensel, René

    2017-01-11

    The benefits of synthetic fibrillar dry adhesives for temporary and reversible attachment to hard objects with smooth surfaces have been successfully demonstrated in previous studies. However, surface roughness induces a dramatic reduction in pull-off stresses and necessarily requires revised design concepts. Toward this aim, we introduce cylindrical two-phase single pillars, which are composed of a mechanically stiff stalk and a soft tip layer. Adhesion to smooth and rough substrates is shown to exceed that of conventional pillar structures. The adhesion characteristics can be tuned by varying the thickness of the soft tip layer, the ratio of the Young's moduli and the curvature of the interface between the two phases. For rough substrates, adhesion values similar to those obtained on smooth substrates were achieved. Our concept of composite pillars overcomes current practical limitations caused by surface roughness and opens up fields of application where roughness is omnipresent.

  4. Numerical study of adhesion enhancement by composite fibrils with soft tip layers

    NASA Astrophysics Data System (ADS)

    Balijepalli, Ram Gopal; Fischer, Sarah C. L.; Hensel, René; McMeeking, Robert M.; Arzt, Eduard

    2017-02-01

    Bio-inspired fibrillar surfaces with reversible adhesion to stiff substrates have been thoroughly investigated over the last decade. In this paper we propose a novel composite fibril consisting of a soft tip layer and stiffer stalk with differently shaped interfaces (flat vs. curved) between them. A tensile stress is applied remotely on the free end of the fibril whose other end adheres to a rigid substrate. The stress distributions and the resulting adhesion of such structures were numerically investigated under plane strain (2 D) and axisymmetric (3 D) conditions. The stress intensities were evaluated for different combinations of layer thickness and Young's moduli. The adhesion strength values were found to increase for thinner layers and larger modulus ratio; these trends are also reflected in selected experimental results. The results of this paper provide a new strategy for optimizing adhesion strength of fibrillar surfaces.

  5. An EMAT-based shear horizontal (SH) wave technique for adhesive bond inspection

    NASA Astrophysics Data System (ADS)

    Arun, K.; Dhayalan, R.; Balasubramaniam, Krishnan; Maxfield, Bruce; Peres, Patrick; Barnoncel, David

    2012-05-01

    The evaluation of adhesively bonded structures has been a challenge over the several decades that these structures have been used. Applications within the aerospace industry often call for particularly high performance adhesive bonds. Several techniques have been proposed for the detection of disbonds and cohesive weakness but a reliable NDE method for detecting interfacial weakness (also sometimes called a kissing bond) has been elusive. Different techniques, including ultrasonic, thermal imaging and shearographic methods, have been proposed; all have had some degree of success. In particular, ultrasonic methods, including those based upon shear and guided waves, have been explored for the assessment of interfacial bond quality. Since 3-D guided shear horizontal (SH) waves in plates have predominantly shear displacement at the plate surfaces, we conjectured that SH guided waves should be influenced by interfacial conditions when they propagate between adhesively bonded plates of comparable thickness. This paper describes a new technique based on SH guided waves that propagate within and through a lap joint. Through mechanisms we have yet to fully understand, the propagation of an SH wave through a lap joint gives rise to a reverberation signal that is due to one or more reflections of an SH guided wave mode within that lap joint. Based upon a combination of numerical simulations and measurements, this method shows promise for detecting and classifying interfacial bonds. It is also apparent from our measurements that the SH wave modes can discriminate between adhesive and cohesive bond weakness in both Aluminum-Epoxy-Aluminum and Composite-Epoxy-Composite lap joints. All measurements reported here used periodic permanent magnet (PPM) Electro-Magnetic Acoustic Transducers (EMATs) to generate either or both of the two lowest order SH modes in the plates that comprise the lap joint. This exact configuration has been simulated using finite element (FE) models to

  6. Fiber/matrix adhesion in graphite/PEKK composites

    NASA Technical Reports Server (NTRS)

    Bucher, R. A.; Hinkley, J. A.

    1992-01-01

    Experiments with poly ether ketone ketone (PEKK) resin and AS-4, IM-7, and G30-500 fibers showed excellent correlation between resin/fiber contact angle and composite transverse flexural strength as measures of resin/fiber interfacial strength. Both tests indicate the strongest interface for G30-500/PEKK followed by IM-7/PEKK and AS-4/PEKK. Also discussed are fiber effects on interlaminar fracture and on the in situ crystallization of the matrix during composite fabrication.

  7. Installation of adhesively bonded composites to repair carbon steel structure.

    SciTech Connect

    Roach, Dennis Patrick; Dunn, Dennis P.; Rackow, Kirk A.

    2003-02-01

    In the past decade, an advanced composite repair technology has made great strides in commercial aviation use. Extensive testing and analysis, through joint programs between the Sandia Labs FAA Airworthiness Assurance Center and the aviation industry, have proven that composite materials can be used to repair damaged aluminum structure. Successful pilot programs have produced flight performance history to establish the viability and durability of bonded composite patches as a permanent repair on commercial aircraft structures. With this foundation in place, efforts are underway to adapt bonded composite repair technology to civil structures. This paper presents a study in the application of composite patches on large trucks and hydraulic shovels typically used in mining operations. Extreme fatigue, temperature, erosive, and corrosive environments induce an array of equipment damage. The current weld repair techniques for these structures provide a fatigue life that is inferior to that of the original plate. Subsequent cracking must be revisited on a regular basis. It is believed that the use of composite doublers, which do not have brittle fracture problems such as those inherent in welds, will help extend the structure's fatigue life and reduce the equipment downtime. Two of the main issues for adapting aircraft composite repairs to civil applications are developing an installation technique for carbon steel structure and accommodating large repairs on extremely thick structures. This paper will focus on the first phase of this study which evaluated the performance of different mechanical and chemical surface preparation techniques. The factors influencing the durability of composite patches in severe field environments will be discussed along with related laminate design and installation issues.

  8. Fiber/matrix adhesion in graphite/PEKK composites

    NASA Technical Reports Server (NTRS)

    Bucher, R. A.; Hinkley, J. A.

    1992-01-01

    Experiments with poly ether ketone ketone (PEKK) resin and AS-4, IM-7, and G30-500 fibers showed excellent correlation between resin/fiber contact angle and composite transverse flexural strength as measures of resin/fiber interfacial strength. Both tests indicate the strongest interface for G30-500/PEKK followed by IM-7/PEKK and AS-4/PEKK. Also discussed are fiber effects on interlaminar fracture and on the in situ crystallization of the matrix during composite fabrication.

  9. Surface preparations for metal frameworks of composite resin veneered prostheses made with an adhesive opaque resin.

    PubMed

    Matsumura, H; Kawahara, M; Tanaka, T; Atsuta, M

    1991-07-01

    Bond strengths of a laboratory developed light-cured composite resin to dental casting alloys were evaluated with a new adhesive opaque resin. The metal specimens were type III gold, nickel-chromium, and cobalt-chromium alloys, while the surface treatments for bonding were heating, Sn plating, and ion coating. The cast metal specimens were "particle blasted" with aluminum oxide and were surface treated. Adhesive 4-META/MMA-TBB opaque resin was applied and a light-cured composite resin was placed over the opaque layer. The prepared specimens were thermocycled in water and shear bond strengths were recorded. The light-cured composite resin was bonded strongly to heated or Sn-plated type III alloy with 4-META/MMA-TBB opaque resin. Copper ion coating in a sputter coater was effective for all three alloys, with only slightly diminished bond strengths. These methods were satisfactory for making composite resin veneered prostheses.

  10. Hemp-Fiber-Reinforced Unsaturated Polyester Composites: Optimization of Processing and Improvement of Interfacial Adhesion

    SciTech Connect

    Qui, Renhui; Ren, Xiaofeng; Fifield, Leonard S.; Simmons, Kevin L.; Li, Kaichang

    2011-02-25

    The processing variables for making hemp-fiber-reinforced unsaturated polyester (UPE) composites were optimized through orthogonal experiments. It was found that the usage of initiator, methyl ethyl ketone peroxide, had the most significant effect on the tensile strength of the composites. The treatment of hemp fibers with a combination of 1, 6-diisocyanatohexane (DIH) and 2-hydroxylethyl acrylate (HEA) significantly increased tensile strength, flexural modulus of rupture and flexural modulus of elasticity, and water resistance of the resulting hemp-UPE composites. FTIR spectra revealed that DIH and HEA were covalently bonded to hemp fibers. Scanning electronic microscopy graphs of the fractured hemp-UPE composites demonstrated that treatment of hemp fibers with a combination of DIH and HEA greatly improved the interfacial adhesion between hemp fibers and UPE. The mechanism of improving the interfacial adhesion is proposed.

  11. Antimicrobial and water-triggered release characteristics of a copper sulfate-polyvinyl acetate adhesive composite

    NASA Astrophysics Data System (ADS)

    De Jesus, A. P. O.; Roxas-Villanueva, R. M. L.; Herrera, M. U.

    2017-05-01

    Water-triggered release of antimicrobial solutions is advantageous in inhibiting the growth of bacteria and fungi in moist and wet environments. In this study, we fabricated a composite, by mixing polyvinyl acetate adhesive with copper sulfate solution, which exhibits antimicrobial activities against bacteria. Polyvinyl acetate adhesive serves as the binder and water soluble substance while copper sulfate serves as the antimicrobial agent. The composite was coated in an acetate film and air-dried. To monitor the rate of release of copper ions, the composite was submerged in water and the conductivity was measured. The conductivity saturation time was determined. The composite showed antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive).

  12. Adhesive/Dentin Interface: The Weak Link in the Composite Restoration

    PubMed Central

    Spencer, Paulette; Ye, Qiang; Park, Jonggu; Topp, Elizabeth M.; Misra, Anil; Marangos, Orestes; Wang, Yong; Bohaty, Brenda S.; Singh, Viraj; Sene, Fabio; Eslick, John; Camarda, Kyle; Katz, J. Lawrence

    2010-01-01

    Results from clinical studies suggest that more than half of the 166 million dental restorations that were placed in the United States in 2005 were replacements for failed restorations. This emphasis on replacement therapy is expected to grow as dentists use composite as opposed to dental amalgam to restore moderate to large posterior lesions. Composite restorations have higher failure rates, more recurrent caries, and increased frequency of replacement as compared to amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and premature failure. Under in vivo conditions the bond formed at the adhesive/dentin interface can be the first defense against these noxious, damaging substances. The intent of this article is to review structural aspects of the clinical substrate that impact bond formation at the adhesive/dentin interface; to examine physico-chemical factors that affect the integrity and durability of the adhesive/dentin interfacial bond; and to explore how these factors act synergistically with mechanical forces to undermine the composite restoration. The article will examine the various avenues that have been pursued to address these problems and it will explore how alterations in material chemistry could address the detrimental impact of physico-chemical stresses on the bond formed at the adhesive/dentin interface. PMID:20195761

  13. Synthesis of imide/arylene ether copolymers for adhesives and composite matrices

    NASA Technical Reports Server (NTRS)

    Jensen, B. J.; Hergenrother, P. M.; Bass, R. G.

    1991-01-01

    A series of imide/arylene ether copolymers were prepared from the reaction of an amorphous arylene ether oligomer and a semi-crystalline imide oligomer. These copolymers were thermally characterized and mechanical properties were measured. One block copolymer was endcapped and the molecular weight was controlled to provide a material that displayed good compression moldability and attractive adhesion and composite properties.

  14. Effect of silorane-based adhesive system on bond strength between composite and dentin substrate

    PubMed Central

    Pereira, Jefferson Ricardo; Júnior, Lindomar Corrêa; de Souza Almeida, Mauro; do Valle, Accácio Lins; Honório, Heitor Marques; Vidotti, Hugo Alberto; De Souza, Grace Mendonca

    2015-01-01

    Context: The complexities of the oral environment, the dentin substrate, and the different bond and composite resin systems represent a challenge to the maintenance of reasonable bond between the composite resin and the tooth structure. Aims: To evaluate the effect of the adhesive system on bond strength between silorane-based composite resin and dentin. Materials and Methods: Fourteen human molars extracted were selected and vertically cut into 3 dentin fragments, randomly divided among the experimental groups and restored with Z250 and P90 composite resin using different adhesive protocols (Adper Single Bond 2, Silorano primer, Adper SE Plus, and Scotchbond Multiuse). Two composite resin cylinders were built up on each dentin surface (n = 10) and subjected to a micro-shear bond strength test. Statistical Analysis Used: Kruskal–Wallis one-way analysis of variance and Tukey test (P = 0.05). Results: According to the results, Kruskal–Wallis test evidenced at least one statistical significant difference (P = 0.001). The Tukey test showed statistically significant differences among the group (P < 0.05). Group PSM8 (P90 + SM) showed statically significant higher results when compared with groups PSP4 (P90 + SP), PSB2 (P90 + SB), and ZSE5 (Z250 + SE). Conclusion: The results evidenced that the monomer of the adhesive system has an effect on bond strength between the composite resin and dentin. PMID:26752846

  15. Structural and in vitro adhesion analysis of a novel covalently coupled bioactive composite.

    PubMed

    Khan, Abdul S; Hassan, Khawaja R; Bukhari, Syeda F; Wong, Ferranti S L; Rehman, Ihtesham U

    2012-01-01

    The interfacial adhesion between a restorative composite and tooth is one of the major factors that determine the ultimate performance of composite restoration. A novel polyurethane (PU) composite material was prepared by chemically binding the nano-hydroxyapatite (nHA) to the diisocyanate component in the PU backbone by utilizing solvent polymerization. The procedure involved stepwise addition of monomeric units of the PU and optimizing the reagent concentrations. The resultant materials were characterized structurally (Raman Spectroscopy) and in vitro bioactive analysis was conducted in modified-simulated body fluid for periodical time intervals. The in vitro study evaluated the push-out bond strength of existing obturating material and novel covalently linked PU/nHA composites to dentin after long-term storage in deionized water and artificial saliva. Human extracted molar roots were filled with experimental samples and analyzed at predetermined time intervals. The shear bond strength of samples was measured and surface morphologies were evaluated. Covalent bond formation was achieved between PU and nHA without intermediate coupling agent. With the increase in concentration of nHA, the composite showed more bioactivity and adhesion toward tooth structure. Bond strength of this new composite were in accordance with obutrating material, therefore, the material can be used as an obturating material because of its direct adhesion with tooth structure.

  16. Failure analysis of adhesively bonded composite joint: an elasto-plastic approach

    NASA Astrophysics Data System (ADS)

    Pradhan, S. C.; Kishore, N. N.; Iyengar, N. G. R.

    1993-09-01

    Joints are important load transferring members in large assembled structures. In joining similar and dissimilar materials, the use of adhesives offers many advantages when compared to other conventional methods. Most commonly used adhesives are the polymers, which exhibit nonlinear behavior. Finite element analysis with paired nodes along the crack path is employed to predict the crack initiation and growth leading to failure. The bond strength is predicted by investigating the possibility of propagation of a crack at the interface of adherend and adhesive. Paired nodes are opened in a sequence, modelling the crack growth. The adhesive is treated to be elasto-plastic for its response. Effect of the parameters such as, stacking sequences in composite adherend, crack growth locations, bond length, bond thicknesses and adhesive stiffnesses on the failure load is studied. The growth of plastic zone as the crack propagates is also examined. On the basis of this study optimal geometrical and material parameters are suggested. The elasto-plastic analysis predicts higher failure loads as compared to linear elastic analysis. The computed bond strength assuming elastic behavior for the adhesive shows satisfactory comparison with experimental results.

  17. Randomized Clinical Trial of Composite Restorations in Primary Teeth: Effect of Adhesive System after Three Years

    PubMed Central

    Donmez, Secil Bektaş; Uysal, Serdar; Ozdemir, Pinar; Tekcicek, Meryem; Zimmerli, Brigitte; Lussi, Adrian

    2016-01-01

    The purpose of this study was to assess the clinical performance of composite restorations placed with different adhesive systems in primary teeth. In 32 patients, 128 composite restorations were placed using a split-mouth design as follows (4 groups/patient): three-step etch-and-rinse (Group 1), two-step etch-and-rinse (Group 2), two-step self-etch (Group 3), and one-step self-etch (Group 4). The restorations were clinically evaluated at baseline and at 6, 18, and 36 months according to the FDI criteria. There was no significant difference between the adhesive systems in retention of the restorations (p > 0.05). Over time, there was a statistically significant decrease in marginal adaptation in all groups, whereas surface and marginal staining significantly increased in Groups 3 and 4 (p < 0.05). The etch-and-rinse adhesive systems resulted in better marginal adaptation than the self-etch adhesive systems (p < 0.05). It was concluded that preetching of the primary enamel might help improve the clinical performance of the self-etch adhesive systems in primary teeth. PMID:27833917

  18. A study on the compatibility between one-bottle dentin adhesives and composite resins using micro-shear bond strength

    PubMed Central

    2015-01-01

    Objectives This study was performed to determine whether the combined use of one-bottle self-etch adhesives and composite resins from same manufacturers have better bond strengths than combinations of adhesive and resins from different manufacturers. Materials and Methods 25 experimental micro-shear bond test groups were made from combinations of five dentin adhesives and five composite resins with extracted human molars stored in saline for 24 hr. Testing was performed using the wire-loop method and a universal testing machine. Bond strength data was statistically analyzed using two way analysis of variance (ANOVA) and Tukey's post hoc test. Results Two way ANOVA revealed significant differences for the factors of dentin adhesives and composite resins, and significant interaction effect (p < 0.001). All combinations with Xeno V (Dentsply De Trey) and Clearfil S3 Bond (Kuraray Dental) adhesives showed no significant differences in micro-shear bond strength, but other adhesives showed significant differences depending on the composite resin (p < 0.05). Contrary to the other adhesives, Xeno V and BondForce (Tokuyama Dental) had higher bond strengths with the same manufacturer's composite resin than other manufacturer's composite resin. Conclusions Not all combinations of adhesive and composite resin by same manufacturers failed to show significantly higher bond strengths than mixed manufacturer combinations. PMID:25671210

  19. Long-term durability of one-step adhesive-composite systems to enamel and dentin.

    PubMed

    Foxton, Richard M; Melo, Luciana; Stone, David G; Pilecki, Peter; Sherriff, Martin; Watson, Timothy F

    2008-01-01

    This study evaluated the long-term durability of three one-step adhesive-composite systems to ground enamel and dentin. Twenty-seven teeth were randomly divided into three groups of nine. The first group had its crowns sectioned to expose superficial dentin, which was then ground with 600 grit SiC paper. One of three one-step adhesives: a trial bonding agent, OBF-2; i Bond or Adper Prompt L-Pop was applied to the dentin of three teeth and built-up with the corresponding resin composite (Estelite sigma, Venus or Filtek Supreme). The second group of nine teeth had their enamel approximal surfaces ground with wet 600-grit SiC paper, then one of the three one-step adhesives was applied and built-up with resin composite. The bonded specimens were sliced into 0.7 mm-thick slabs. After 24 hours and one year of water storage at 37 degrees C, the slabs were sectioned into beams for the microtensile bond strength test. Failure modes were observed using optical and electron scanning microscopy. The third group of nine teeth had approximal wedge-shaped cavities prepared above the CEJ into dentin. Two-to-three grains of rhodamine B were added to each of the three adhesives prior to restoring the cavities with resin composite. After 24 hours storage, the teeth were sectioned and their interfaces examined with a laser scanning confocal microscope. The bond strengths of the three adhesive-composite systems to both enamel and dentin significantly lessened after one year of water storage, however, there was no significant difference between the materials.

  20. Shear bond strength between alumina substrate and prosthodontic resin composites with various adhesive resin systems.

    PubMed

    AlJehani, Yousef A; Baskaradoss, Jagan K; Geevarghese, Amrita; AlShehry, Marey A; Vallittu, Pekka K

    2015-05-02

    With the increase in demand for cosmetics and esthetics, resin composite restorations and all-ceramic restorations have become an important treatment alternative. Taking into consideration the large number of prosthodontic and adhesive resins currently available, the strength and durability of these materials needs to be evaluated. This laboratory study presents the shear bond strengths of a range of veneering resin composites bonded to all-ceramic core material using different adhesive resins. Alumina ceramic specimens (Techceram Ltd, Shipley, UK) were assigned to three groups. Three types of commercially available prosthodontic resin composites [BelleGlass®, (BG, Kerr, CA, USA), Sinfony® (SF, 3 M ESPE, Dental Products, Germany), and GC Gradia® (GCG, GC Corp, Tokyo, Japan)] were bonded to the alumina substrate using four different adhesive resins. Half the specimens per group (N = 40) were stored dry for 24 hours, the remaining were stored for 30 days in water. The bonding strength, so-called shear bond strengths between composite resin and alumina substrate were measured. Data were analysed statistically and variations in bond strength within each group were additionally evaluated by calculating the Weibull modulus. Bond strengths were influenced by the brand of prosthodontic resin composites. Shear bond strengths of material combinations varied from 24.17 ± 3.72-10.15 ± 3.69 MPa and 21.20 ± 4.64-7.50 ± 4.22 at 24 h and 30 days, respectively. BG resin composite compared with the other resin composites provided the strongest bond with alumina substrate (p < 0.01). SF resin composite was found to have a lower bond strength than the other composites. The Weibull moduli were highest for BG, which was bonded by using Optibond Solo Plus adhesive resin at 24 h and 30 days. There was no effect of storage time and adhesive brand on bond strength. Within the limitations of this study, the shear bond strengths of composite resins to alumina substrate are related to

  1. Polymer composition and substrate influences on the adhesive bonding of a biomimetic, cross-linking polymer.

    PubMed

    Matos-Pérez, Cristina R; White, James D; Wilker, Jonathan J

    2012-06-06

    Hierarchical biological materials such as bone, sea shells, and marine bioadhesives are providing inspiration for the assembly of synthetic molecules into complex structures. The adhesive system of marine mussels has been the focus of much attention in recent years. Several catechol-containing polymers are being developed to mimic the cross-linking of proteins containing 3,4-dihydroxyphenylalanine (DOPA) used by shellfish for sticking to rocks. Many of these biomimetic polymer systems have been shown to form surface coatings or hydrogels; however, bulk adhesion is demonstrated less often. Developing adhesives requires addressing design issues including finding a good balance between cohesive and adhesive bonding interactions. Despite the growing number of mussel-mimicking polymers, there has been little effort to generate structure-property relations and gain insights on what chemical traits give rise to the best glues. In this report, we examine the simplest of these biomimetic polymers, poly[(3,4-dihydroxystyrene)-co-styrene]. Pendant catechol groups (i.e., 3,4-dihydroxystyrene) are distributed throughout a polystyrene backbone. Several polymer derivatives were prepared, each with a different 3,4-dihyroxystyrene content. Bulk adhesion testing showed where the optimal middle ground of cohesive and adhesive bonding resides. Adhesive performance was benchmarked against commercial glues as well as the genuine material produced by live mussels. In the best case, bonding was similar to that obtained with cyanoacrylate "Krazy Glue". Performance was also examined using low- (e.g., plastics) and high-energy (e.g., metals, wood) surfaces. The adhesive bonding of poly[(3,4-dihydroxystyrene)-co-styrene] may be the strongest of reported mussel protein mimics. These insights should help us to design future biomimetic systems, thereby bringing us closer to development of bone cements, dental composites, and surgical glues.

  2. Polymer Composition and Substrate Influences on the Adhesive Bonding of a Biomimetic, Cross-Linking Polymer

    PubMed Central

    Matos-Pérez, Cristina R.; White, James D.; Wilker, Jonathan J.

    2012-01-01

    Hierarchical biological materials such as bone, sea shells, and marine bioadhesives are providing inspiration for the assembly of synthetic molecules into complex structures. The adhesive system of marine mussels has been the focus of much attention in recent years. Several catechol-containing polymers are being developed to mimic the cross-linking of proteins containing 3,4-dihydroxyphenylalanine (DOPA) used by shellfish for sticking to rocks. Many of these biomimetic polymer systems have been shown to form surface coatings or hydrogels, however bulk adhesion is demonstrated less often. Developing adhesives requires addressing design issues including finding a good balance between cohesive and adhesive bonding interactions. Despite the growing number of mussel mimicking polymers, there has been little effort to generate structure-property relations and gain insights on what chemical traits give rise to the best glues. In this report, we examined the simplest of these biomimetic polymers, poly[(3,4-dihydroxystyrene)-co-styrene]. Pendant catechol groups (i.e., 3,4-dihydroxystyrene) were distributed throughout a polystyrene backbone. Several polymer derivatives were prepared, each with a different 3,4-dihyroxystyrene content. Bulk adhesion testing showed where the optimal middle ground of cohesive and adhesive bonding resides. Adhesive performance was benchmarked against commercial glues as well as the genuine material produced by live mussels. In the best case, bonding was similar to cyanoacrylate “Krazy” or “Super” glue. Performance was also examined using low (e.g., plastics) and high (e.g., metals, wood) energy surfaces. Adhesive bonding of poly[(3,4-dihydroxystyrene)-co-styrene] may be the strongest of reported mussel protein mimics. These insights should help us to design future biomimetic systems, thereby bringing us closer to development of bone cements, dental composites, and surgical glues. PMID:22582754

  3. Polyelectrolytes Multilayers to Modulate Cell Adhesion: A Study of the Influence of Film Composition and Polyelectrolyte Interdigitation on the Adhesion of the A549 Cell Line.

    PubMed

    Muzzio, Nicolás E; Pasquale, Miguel A; Gregurec, Danijela; Diamanti, Eleftheria; Kosutic, Marija; Azzaroni, Omar; Moya, Sergio E

    2016-04-01

    Polyelectrolyte multilayers (PEMs) with different polycation/polyanion pairs are fabricated by the layer-by-layer technique employing synthetic, natural, and both types of polyelectrolytes. The impact of the chemical composition of PEMs on cell adhesion is assessed by studying cell shape, spreading area, focal contacts, and cell proliferation for the A549 cell line. Cells exhibit good adhesion on PEMs containing natural polycations and poly(sodium 4-styrenesulfonate) (PSS) as polyanion, but limited adhesion is observed on PEMs fabricated from both natural polyelectrolytes. PEMs are then assembled, depositing a block of natural polyelectrolytes on top of a stiffer block with PSS as polyanion. Cell adhesion is enhanced on top of the diblock PEMs compared to purely natural PEMs. This fact could be explained by the interdigitation between polyelectrolytes from the two blocks. Diblock PEM assembly provides a simple means to tune cell adhesion on biocompatible PEMs.

  4. Elastomer toughened polyimide adhesives. [bonding metal and composite material structures for aircraft and spacecraft

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L. (Inventor)

    1985-01-01

    A rubber-toughened, addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber-containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride has been mixed, and utilizing solvent or mixture of solvents for the reaction.

  5. Adhesive Bonding of Titanium to Carbon-Carbon Composites for Heat Rejection Systems

    NASA Technical Reports Server (NTRS)

    Cerny, Jennifer; Morscher, Gregory

    2006-01-01

    High temperature adhesives with good thermal conductivity, mechanical performance, and long term durability are crucial for the assembly of heat rejection system components for space exploration missions. In the present study, commercially available adhesives were used to bond high conductivity carbon-carbon composites to titanium sheets. Bonded pieces were also exposed to high (530 to 600 Kelvin for 24 hours) and low (liquid nitrogen 77K for 15 minutes) temperatures to evaluate the integrity of the bonds. Results of the microstructural characterization and tensile shear strengths of bonded specimens will be reported. The effect of titanium surface roughness on the interface microstructure will also be discussed.

  6. The effect of elevated temperatures on the dentin adhesion of resin composites.

    PubMed

    Brackett, William W; Covey, David A; Haisch, Larry D

    2003-01-01

    Although resin composite restorations may undergo relatively extreme temperature changes in the oral cavity, little is known about the effects of temperature on their adhesion to tooth structure. This study evaluated the effect of temperature on shear bond strength to dentin of three commercial resin dentin adhesives through testing of matured specimens over the 20 degrees to 55 degrees C temperature range. A significant difference (p < 0.05) was observed between 20 degrees C and 55 degrees C for all the materials, and for one of the materials, a significant difference was also observed between 20 degrees C and 37 degrees C.

  7. [Bond strength to dentin of resin composites associated with filled and unfilled adhesive systems].

    PubMed

    Youssef, J A; Turbino, M L; Youssef, M N; Matson, E

    2001-01-01

    This study analyzed in vitro two brands of one-step adhesive systems of fourth generation (Optisolo--Kerr, filled; and Single Bond--3M, unfilled) and two composite resins (Prodigy--Kerr and Z100--3M), aiming at evaluating their bond strength to dentin. Eighty human extracted molars were embedded in acrylic resin and grounded until dentin was exposed in longitudinal direction. The specimens were divided in 4 groups. Composite resin cones were bonded to the specimens using the mentioned adhesive systems, following the instructions of the manufacturers. The test-specimens were submitted to tensile tests using a 4442 Universal Mini-Instron Machine with the speed of 0.5 mm/min. The results were converted into MPa, according to the area of adhesion, and submitted to statistical analysis with ANOVA. There was significant statistical difference (p < 0.01) between the adhesive systems (F = 7.24). Optisolo (m = 11.03 +/- 4.23) showed better bond strength than Single Bond (m = 8.37 +/- 4.54). There was no significant statistical difference (p > 0.05) between the composites (F = 0.43).

  8. Adhesive Cementation of Indirect Composite Inlays and Onlays: A Literature Review.

    PubMed

    D'Arcangelo, Camillo; Vanini, Lorenzo; Casinelli, Matteo; Frascaria, Massimo; De Angelis, Francesco; Vadini, Mirco; D'Amario, Maurizio

    2015-09-01

    The authors conducted a literature review focused on materials and techniques used in adhesive cementation for indirect composite resin restorations. It was based on English language sources and involved a search of online databases in Medline, EMBASE, Cochrane Library, Web of Science, Google Scholar, and Scopus using related topic keywords in different combinations; it was supplemented by a traditional search of peer-reviewed journals and cross-referenced with the articles accessed. The purpose of most research on adhesive systems has been to learn more about increased bond strength and simplified application methods. Adherent surface treatments before cementation are necessary to obtain high survival and success rates of indirect composite resin. Each step of the clinical and laboratory procedures can have an impact on longevity and the esthetic results of indirect restorations. Cementation seems to be the most critical step, and its long-term success relies on adherence to the clinical protocols. The authors concluded that in terms of survival rate and esthetic long-term outcomes, indirect composite resin techniques have proven to be clinically acceptable. However, the correct management of adhesive cementation protocols requires knowledge of adhesive principles and adherence to the clinical protocol in order to obtain durable bonding between tooth structure and restorative materials.

  9. Adhesively bonded steel and composites-durability in substitute ocean water

    SciTech Connect

    Aartun, L.; Dillard, J.G.

    1996-12-31

    Ocean water, marine life and certain oil-well fluids constitute a highly aggressive environment for most metals. In the offshore oil industry, the economic driving force to seek new materials points towards polymeric composites which offer reduction of weight and elimination of corrosion. However, a combined use of steel and composites creates a joining problem. Exposure to humid air and liquid water affects adhesive bonds in a negative manner, and adhesively bonded metal systems are even less durable in marine than in non-ocean environments. In marine environments and sea coast atmospheres, marine life and salts can contribute to the degradation process. On an operating oil rig, repair and replacements involving adhesive bonding are forced to be carried out under non-ideal conditions because of environmental regulations (affecting surface treatments) and safety requirements (affecting the curing method). The objective of this work is to develop environmentally friendly surface preparations and to study, the influence of salt water on the durability of adhesively bonded steel/composite systems.

  10. Purification, composition, and structure of macrophage adhesion molecule

    SciTech Connect

    Remold-O'Donnell, E.; Savage, B.

    1988-01-12

    Macrophage adhesion molecule (MAM) is a surface heterodimer consisting of the trypsin- and plasmin-sensitive glycopeptide gp160 (MAM-..cap alpha..) and the glycopeptide gp93 (MAM-..beta..). MAM, which is the guinea pig analog of Mo1 and Mac-1, was purified from detergent lysates of peritoneal neutrophils by lentil lectin chromatography and M2-antibody chromatography. The pure heterodimer molecule was dissociated by acidic conditions (pH 3.5), and MAM-..cap alpha.. and MAM-..beta.. were separated by M7-antibody chromatography. MAM-..beta.. is an approx. 640 amino acid residue polypeptide with exceptionally high cysteine content. At 7.2 residues per 100 amino acids, Cys/2 of MAM-..beta.. is more than 3 times the mean for 200 purified proteins. Reactivity with six ..beta..-subunit-specific /sup 125/I-labeled monoclonal antibodies recognizing at least four epitopes demonstrated that intrapeptide disulfide bonds are required to maintain the structure of MAM-..beta... All six antibodies failed to react when MAM-..beta.. was treated with reducing agents. MAM-..beta.. is 18% carbohydrate; the major monosaccharides are mannose, N-acetylglucosamine, galactose, and sialic acid. MAM-..beta.. is estimated to contain five to six N-linked carbohydrate units. MAM-..cap alpha.. is an approx. 1100-residue polypeptide with lower Cys/2 content (2.0 residues per 100 amino acid residues). MAM-..cap alpha.. is 21% carbohydrate. The major monosaccharides are mannose, N-acetylglucosamine, galactose, and sialic acid; the mannose content is higher in MAM-..cap alpha.. than MAM-..beta.. is estimated to contain 12 N-linked carbohydrate units.

  11. Damage state evaluation of adhesive composite joints using chaotic ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Fasel, Timothy R.; Todd, Michael D.; Park, Gyuhae

    2009-03-01

    Ultrasonic chaotic excitations combined with sensor prediction algorithms have shown the ability to identify incipient damage (loss of preload) in a bolted joint. In this study we examine the capability of this damage detection scheme to identify disbonds and poorly cured bonds in a composite-to-composite adhesive joint. The test structure consists of a carbon fiber reinforced polymer (CFRP) plate that has been bonded to a CFRP rectangular tube/spar with several sizes of disbond as well as a poorly cured section. Each excitation signal is imparted to the CFRP plate through a macro-fiber composite (MFC) patch on one side of the adhesive joint and sensed using an equivalent MFC patch on the opposite side of the joint. A novel statistical classification feature is developed from information theory concepts of cross-prediction and interdependence. Temperature dependence of this newly developed feature will also be examined.

  12. Effect of low-shrinking composite on the bonding effectiveness of two adhesives in occlusal Class-I cavities.

    PubMed

    Mine, Atsushi; De Munck, Jan; Cardoso, Marcio V; Van Landuyt, Kirsten L; Poitevin, André; Kuboki, Takuo; Yoshida, Yasuhiro; Suzuki, Kazuomi; Van Meerbeek, Bart

    2012-01-01

    The purpose of this study was to evaluate if a low-shrinking composite can improve the bonding effectiveness of adhesives in highly constrained conditions. A low-shrinking composite ('els-extra low shrinkage', Saremco) was bonded in standardized occlusal Class-I cavities using a three-step ('cmf', Saremco) and a two-step etch-and-rinse adhesive ('XP Bond', Dentsply). Both adhesives were also combined with a conventional composite ('Z100', 3M ESPE). Half of the restored cavities were exposed to 20,000 thermo-cycles. 3-way ANOVA revealed a significant effect for the factors 'adhesive' and 'composite' (both p<0.0001), but not for 'thermo-cycling' (p=0.994). Significantly higher bond strengths were recorded for the low-shrinking composite than for the control composite, using either of the adhesives. The low-shrinking composite in combination with the three-step etch-and-rinse adhesive performed best in the high C-factor Class-I cavity. The two-step etch-and-rinse adhesive suffered strongly from polymerization-shrinkage stress, which could be partially restored by using the low-shrinking composite.

  13. Creep Stress Redistribution of Single-Lap Weldbonded Joint

    NASA Astrophysics Data System (ADS)

    Yin, Yong; Chen, Jian-Jun; Tu, Shan-Tung

    2005-01-01

    Weldbonding is a new joining technique that combines the spot welding with the adhesive bonding. It has found more and more applications in recent years because of its unique advantages. However, researches on the new technique are few especially on the long-term stress and strength of weldbonded structures. In the present paper, three-dimensional viscoplastic finite element analyses (FEA) of a single-lap weldbonded joint are conducted to investigate the stress redistribution. The results show that stresses increase obviously near the interface between the adhesive and the weld spot with the creep of adhesive. The adhesive tends to distribute its stresses more uniformly and transfer some loads to the weld spot. The stress concentration factor of weldbonded joint is significantly lower than that of the direct spot-weld in connection. The simulations illustrate that increasing of creep parameter will enhance the maximum stress level in the weld spot.

  14. Cashier/Checker Learning Activity Packets (LAPs).

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Twenty-four learning activity packets (LAPs) are provided for six areas of instruction in a cashier/checker program. Section A, Orientation, contains an LAP on exploring the job of cashier-checker. Section B, Operations, has nine LAPs, including those on operating the cash register, issuing trading stamps, and completing the cash register balance…

  15. Cashier/Checker Learning Activity Packets (LAPs).

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Twenty-four learning activity packets (LAPs) are provided for six areas of instruction in a cashier/checker program. Section A, Orientation, contains an LAP on exploring the job of cashier-checker. Section B, Operations, has nine LAPs, including those on operating the cash register, issuing trading stamps, and completing the cash register balance…

  16. Impact of different adhesives on work of adhesion between CAD/CAM polymers and resin composite cements.

    PubMed

    Keul, Christine; Müller-Hahl, Manuel; Eichberger, Marlis; Liebermann, Anja; Roos, Malgorzata; Edelhoff, Daniel; Stawarczyk, Bogna

    2014-09-01

    To determine the impact of pre-treatment of adhesive systems on the work of adhesion (WA) between CAD/CAM polymers and resin composite cements and compare with conventional tests of previous studies. Surface parameters were measured by contact angle measurement (2700 measurements) and WA was calculated. Five CAD/CAM polymers were used for fabrication of specimens (n=75/subgroup): artBloc Temp (A), Telio CAD (B), Nano Composite CFI-C (C), exp. CAD/CAM nanohybrid composite (D), and LAVA Ultimate (E). Then, air-abraded specimens were pre-treated (n=15 per group): Ambarino P60 (I), Monobond Plus/Heliobond (II), visio.link (III), VP connect (IV), and no pre-treatment (V). Resin composite cement specimens (n=75) were smoothed out homogeneously on a glass plate (n=15/group): RelyX ARC (RXA), Variolink II (VAR), Panavia F2.0 (PAN), RelyX Unicem (RXU), and Clearfil SA Cement (CSA). Contact angles were determined with 3 drops of distilled water and diiodomethane each. Data were analyzed using Kruskal-Wallis-H test and Spearman-Rho correlation (p<0.05). CAD/CAM materials (B), (A), and (C) showed higher WA compared to (D) and (E). (II) and (IV) resulted in higher WA than (I), (III) and (V). VAR had the significantly lowest WA, followed by RXU, RXA, CSA and PAN. No correlation occurred between WA and TBS/SBS whereas polar component of surface free energy of CAD/CAM resin and spreading coefficient showed significant positive correlation with TBS/SBS. Determination of WA is not a proper method to draw conclusions about the bond between resin materials. Destructive test methods are not dispensable. The successful outcome of fixed dental restorations depends, among others, on the quality of bonding between the tooth and the restoration. Additional pre-treatment of the dental CAD/CAM resin restoration by bonding systems can be recommended for clinical use. Pre-treatment showed a significant impact on the surface properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Bond strength between composite resin and resin modified glass ionomer using different adhesive systems and curing techniques.

    PubMed

    Boruziniat, Alireza; Gharaei, Samineh

    2014-03-01

    To evaluate bond strength between RMGI and composite using different adhesive systems and curing techniques. Sixty prepared samples of RMGI were randomly divided into six groups according to adhesive systems (total-etch, two-step self-etch and all-in-one) and curing techniques (co-curing and pre-curing). In co-curing technique, the adhesive systems were applied on uncured RMGI samples and co-cured together. In the pre-curing technique, before application of adhesive systems, the RMGI samples were cured. Composite layers were applied and shear bond strength was measured. Two samples of each group were evaluated by SEM. Failure mode was determined by streomicroscope. Both curing methods and adhesive systems had significant effect on bond strength (P-value < 0.05). There was an interaction between two factors (P-value <0.05). Both self-etch adhesives had significantly higher shear bond strength than the total-etch adhesive (P-value <0.05). The co-curing technique improved the bond strength in self-etch adhesives, but decreased the bond strength in total-etch adhesive (P-value<0.05). The application of self-etch adhesive systems and co-curing technique can improve the bond strength between the RMGI and composite.

  18. Limited interaction of a self-adhesive flowable composite with dentin/enamel characterized by TEM.

    PubMed

    Mine, Atsushi; De Munck, Jan; Van Ende, Annelies; Poitevin, André; Matsumoto, Mariko; Yoshida, Yasuhiro; Kuboki, Takuo; Van Landuyt, Kirsten L; Yatani, Hirofumi; Van Meerbeek, Bart

    2017-02-01

    A new category of composite which does not require any acid etching or bonding protocol prior to application has been introduced. The purpose of this study was to characterize the interfacial ultra-structure at enamel and dentin surfaces by means of transmission electron microscopy (TEM). Non-carious human third molars were randomly divided into 6 groups (bur-cut dentin, SiC-ground dentin, fractured dentin, bur-cut enamel, SiC-ground enamel, and un-cut enamel). After preparation of the respective surfaces, the self-adhesive flowable composite (Vertise Flow, Kerr) was applied. Non-demineralized/demineralized and non-stained/stained sections of 70-90nm were prepared following common TEM-specimen processing procedures. Additional specimens were immersed in an ammoniacal silver nitrate solution. The composite-dentin interface was free of voids and no de-bonding occurred during specimen preparation. For bur-cut and SiC-ground dentin, no surface demineralization was observed and the smear contained residual hydroxyapatite. On fractured dentin (i.e. without smear interference), a very thin interaction area of 100-200nm without apparent signs of surface demineralization was seen. When the composite was bonded to enamel, a distinct separation between the self-adhesive composite and enamel was present in all three groups. A tight interaction, yet without distinct dissolution of hydroxyapatite, could only be seen in some regions at bur-cut enamel where smear was absent or sparse. Silver nitrate infiltration was associated with the presence of smear. The self-adhesive composite showed limited interaction with smear-covered substrates and aprismatic enamel, which explains its inferior diminished bonding capacity in comparison with current adhesives. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Stress Analysis of Adhesively Bonded Repairs to Fibre Composite Structures,

    DTIC Science & Technology

    1981-03-01

    which is bonded to a thin sheet of fibre composite material. The x and y axes are taken in a plane parallel to the midsurface of the sheet with the z...SHEET vI X1 FIG. 1 AXIS SYSTEM IN PATCH related to the displacements at the midsurface of the patch, which we will denote by uo, vo and w, and the...displacements at the midsurface of the sheet, which we will denote by u, vs and w, by the following expression: T ( =uo - us +f7 ’ f/fg + (VO - v, +f 7 3)f4

  20. Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

    PubMed Central

    TÜRKMEN, Cafer; DURKAN, Meral; CİMİLLİ, Hale; ÖKSÜZ, Mustafa

    2011-01-01

    Objective The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. Material and Methods Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student's t-test. The failure modes of all groups were also evaluated. Results The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. Conclusion The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces. PMID:21710095

  1. Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations.

    PubMed

    Kubo, Shisei; Yokota, Hiroaki; Yokota, Haruka; Hayashi, Yoshihiko

    2013-01-01

    The incidence of non-carious cervical lesions (NCCLs) has been increasing. The clinical performance of resin composites in NCCLS was previously unsatisfactory due to their non-retentive forms and margins lying on dentin. In order to address this problem, a lot of effort has been put into developing new dentin adhesives and restorative techniques. This article discusses these challenges and the criteria used for evaluating clinical performance as they relate to clinical studies, especially long-term clinical trials. Polymerization contraction, thermal changes and occlusal forces generate debonding stresses at adhesive interfaces. In laboratory studies, we have investigated how these stresses can be relieved by various restorative techniques and how bond strength and durability can be enhanced. Lesion forms, restorative techniques, adhesives (adhesive strategies, bond strengths, bond durability, and the relationship between enamel and dentin bond strengths) were found to have a complex relationship with microleakage. With regard to some restorative techniques, only several short-term clinical studies were available. Although in laboratory tests marginal sealing improved with a low-viscosity resin liner, an enamel bevel or prior enamel etching with phosphoric acid, clinical studies failed to detect significant effects associated with these techniques. Long-term clinical trials demonstrated that adhesive bonds continuously degraded in various ways, regardless of the adhesion strategy used. Early loss of restoration may no longer be the main clinical problem when reliable adhesives are properly used. Marginal discoloration increased over time and may become a more prominent reason for repair or replacement. Reliable and standardized criteria for the clinical evaluation of marginal discoloration should be established as soon as possible and they should be based on evidence and a policy of minimal intervention. Copyright © 2012 Academy of Dental Materials. Published by

  2. In vivo evaluation of microleakage from composites with new dentine adhesives.

    PubMed

    Koliniotou-Koumpia, E; Dionysopoulos, P; Koumpia, E

    2004-10-01

    The purpose of this study was to investigate microleakage in V class composite restorations with total etch versus self-etching adhesives. Experiments were conducted in vivo and were also evaluated interfacial micromorphology. Forty class V cavities were prepared on the buccal surfaces of teeth in three healthy dogs. The cavities were randomly assigned into five groups of eight teeth and restored with one of the following adhesive systems: Etch and Prime 3.0/Definite flow/Definite, Prompt L-pop/Filtek flow/P-60, Admira bond/Admira Flow /Admira, Bond 1/Flow it/Alert, Stae/Wave/Glacier. After 60 days the animals were killed and the teeth were extracted. The teeth were then immersed in a solution of 0.5% basic fuchsin dye for 24 h, sectioned and scored for microleakage. Features of the tooth/restoration interfaces were also examined using Scanning electron microscopy. Student-Newman-Keuls and one-way anova revealed significance differences among the groups for overall wall scores (P < 0.05). The total-etch adhesives revealed significantly less microleakage scores than the self-etching adhesive systems tested. Wilcoxon Signed Ranks Test revealed significant differences between the occlusal and gingival microleakage scores for each adhesive restorative system, with the exception of Admira (P < 0.05).

  3. Expression of Surface Protein LapB by a Wide Spectrum of Listeria monocytogenes Serotypes as Demonstrated with Anti-LapB Monoclonal Antibodies

    PubMed Central

    Boivin, Teela; Elmgren, Cathie; Brooks, Brian W.; Huang, Hongsheng; Pagotto, Franco

    2016-01-01

    ABSTRACT Protein antigens expressed on the surface of all strains of Listeria monocytogenes and absent from nonpathogenic Listeria spp. are presumably useful targets for pathogen identification, detection, and isolation using specific antibodies (Abs). To seek such surface proteins expressed in various strains of L. monocytogenes for diagnostic applications, we focused on a set of surface proteins known to be involved or putatively involved in L. monocytogenes virulence and identified Listeria adhesion protein B (LapB) as a candidate based on the bioinformatics analysis of whole-genome sequences showing that the gene coding for LapB was present in L. monocytogenes strains and absent from strains of other Listeria spp. Immunofluorescence microscopy (IFM), performed with rabbit polyclonal antibodies against the recombinant LapB protein (rLapB) of L. monocytogenes serotype 4b strain L10521, confirmed expression of LapB on the surface. A panel of 48 mouse monoclonal antibodies (MAbs) to rLaB was generated, and 7 of them bound strongly to the surface of L. monocytogenes cells as demonstrated using IFM. Further characterization of these 7 anti-LapB MAbs, using an enzyme-linked immunosorbent assay (ELISA), revealed that 6 anti-LapB MAbs (M3484, M3495, M3500, M3509, M3517, and M3519) reacted strongly with 46 (86.8%) of 53 strains representing 10 of the 12 serotypes tested (1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4ab, 4b, 4d, and 4e). These results indicate that LapB, together with companion anti-LapB MAbs, can be targeted as a biomarker for the detection and isolation of various L. monocytogenes strains from contaminated foods. IMPORTANCE Strains of L. monocytogenes are traditionally grouped into serotypes. Identification of a surface protein expressed in all or the majority of at least 12 serotypes would aid in the development of surface-binding monoclonal antibodies (MAbs) for detection and isolation of L. monocytogenes from foods. Bioinformatics analysis revealed that the gene

  4. Engineering adhesion to thermoresponsive substrates: effect of polymer composition on liquid-liquid-solid wetting.

    PubMed

    Gambinossi, Filippo; Sefcik, Lauren S; Wischerhoff, Erik; Laschewsky, Andre; Ferri, James K

    2015-02-04

    Adhesion control in liquid-liquid-solid systems represents a challenge for applications ranging from self-cleaning to biocompatibility of engineered materials. By using responsive polymer chemistry and molecular self-assembly, adhesion at solid/liquid interfaces can be achieved and modulated by external stimuli. Here, we utilize thermosensitive polymeric materials based on random copolymers of di(ethylene glycol) methyl ether methacrylate (x = MEO2MA) and oligo(ethylene glycol) methyl ether methacrylate (y = OEGMA), that is, P(MEO2MAx-co-OEGMAy), to investigate the role of hydrophobicity on the phenomenon of adhesion. The copolymer ratio (x/y) dictates macromolecular changes enabling control of the hydrophilic-to-lipophilic balance (HBL) of the polymer brushes through external triggers such as ionic strength and temperature. We discuss the HBL of the thermobrushes in terms of the surface energy of the substrate by measuring the contact angle at water-decane-P(MEO2MAx-co-OEGMAy) brush contact line as a function of polymer composition and temperature. Solid supported polyelectrolyte layers grafted with P(MEO2MAx-co-OEGMAy) display a transition in the wettability that is related to the lower critical solution temperature of the polymer brushes. Using experimental observation of the hydrophilic to hydrophobic transition by the contact angle, we extract the underlying energetics associated with liquid-liquid-solid adhesion as a function of the copolymer ratio. The change in cellular attachment on P(MEO2MAx-co-OEGMAy) substrates of variable (x/y) composition demonstrates the subtle role of compositional tuning on the ability to control liquid-liquid-solid adhesion in biological applications.

  5. Structural, Surface, in vitro Bacterial Adhesion and Biofilm Formation Analysis of Three Dental Restorative Composites

    PubMed Central

    Azam, Maria T.; Khan, Abdul S.; Muzzafar, Danish; Faryal, Rani; Siddiqi, Saadat A.; Ahmad, Riaz; Chauhdry, Aqif A.; Rehman, Ihtesham U.

    2015-01-01

    This study was conducted to investigate the relationship between dental materials and bacterial adhesion on the grounds of their chemical composition and physical properties. Three commercially available dental restorative materials (Filtek™Z350, Filtek™P90 and Spectrum®TPH®) were structurally analyzed and their wettability and surface roughness were evaluated by using Fourier Transform Infrared Spectroscopy, Contact Angle Measurement and Atomic Force Microscopy, respectively. These materials were molded into discs and tested with three bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia) for microbial attachment. The bacterial adhesion was observed at different time intervals, i.e., 0 h, 8 h, 24 h, 48 h and 72 h, along with Colony Forming Unit Count and Optical Density measurement of the media. It was found that all materials showed a degree of conversion with time intervals, i.e., 0 h, 8 h, 24 h, 48 h and 72 h, which led to the availability of functional groups (N–H and C–H) that might promote adhesion. The trend in difference in the extent of bacterial adhesion can be related to particle size, chemical composition and surface wettability of the dental materials.

  6. Influence of Copolyester Composition on Adhesion to Soda-Lime Glass via Molecular Dynamics Simulations.

    PubMed

    Hanson, Ben; Hofmann, John; Pasquinelli, Melissa A

    2016-06-01

    Copolyesters are a subset of polymers that have the desirable properties of strength and clarity while retaining chemical resistance, and are thus potential candidates for enhancing the impact resistance of soda-lime glass. Adhesion between the polymer and the glass relates to the impact performance of the system, as well as the longevity of the bond between the polymer and the glass under various conditions. Modifying the types of diols and diacids present in the copolyester provides a method for fine-tuning the physical properties of the polymer. In this study, we used molecular dynamics (MD) simulations to examine the influence of the chemical composition of the polymers on adhesion of polymer film laminates to two soda-lime glass surfaces, one tin-rich and one oxygen-rich. By calculating properties such as adhesion energies and contact angles, these results provide insights into how the polymer-glass interaction is impacted by the polymer composition, temperature, and other factors such as the presence of free volume or pi stacking. These results can be used to optimize the adhesion of copolyester films to glass surfaces.

  7. Fatigue resistance and failure mode of adhesively restored custom metal-composite resin premolar implant abutments.

    PubMed

    Boff, Luís Leonildo; Oderich, Elisa; Cardoso, Antônio Carlos; Magne, Pascal

    2014-01-01

    To evaluate the fatigue resistance and failure mode of composite resin and porcelain onlays and crowns bonded to premolar custom metal-composite resin premolar implant abutments. Sixty composite resin mesostructures were fabricated with computer assistance with two preparation designs (crown vs onlay) and bonded to a metal implant abutment. Following insertion into an implant with a tapered abutment interface (Titamax CM), each metal-composite resin abutment was restored with either composite resin (Paradigm MZ100) or ceramic (Paradigm C) (n = 15) and attached with adhesive resin (Optibond FL) and a preheated light-curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz) was then simulated, starting with 5,000 cycles at a load of 50 N, followed by stages of 200, 400, 600, 800, 1,000, 1,200, and 1,400 N (25,000 cycles each). Samples were loaded until fracture or to a maximum of 180,000 cycles. The four groups were compared using life table survival analysis (log-rank test). Previously published data using zirconia abutments of the same design were included for comparison. Paradigm C and MZ100 specimens fractured at average loads of 1,133 N and 1,266 N, respectively. Survival rates ranged from 20% to 33.3% (ceramic crowns and onlays) to 60% (composite resin crowns and onlays) and were significantly different (pooled data for restorative material). There were no restoration failures, but there were adhesive failures at the connection between the abutment and the mesostructure. The survival of the metal-composite resin premolar abutments was inferior to that of identical zirconia abutments from a previous study (pooled data for abutment material). Composite resin onlays/crowns bonded to metal-composite resin premolar implant abutments presented higher survival rates than comparable ceramic onlays/crowns. Zirconia abutments outperformed the metal-composite resin premolar abutments.

  8. Analytical and experimental investigation of fatigue in lap joints

    NASA Astrophysics Data System (ADS)

    Swenson, Daniel V.; Chih-Chien, Chia; Derber, Thomas G.

    A finite element model is presented that can simulate crack growth in layered structures such as lap joints. The layers can be joined either by rivets or adhesives. The crack is represented discretely in the mesh, and automatic remeshing is performed as the crack grows. Because of the connections between the layers, load is transferred to the uncracked layer as the crack grows. This reduces the stress intensity and slows the crack growth rate. The model is used to analyze tests performed on a section of a wing spanwise lap joint. The crack was initiated at a rivet and grown under constant amplitude cyclic loads. Both experimentally observed crack growth rates and the analysis show the retardation that occurs as a result of load transfer between layers. A good correlation is obtained between predicted and observed crack growth rates for the fullly developed through-thickness crack.

  9. Additive manufacturing of tools for lapping glass

    NASA Astrophysics Data System (ADS)

    Williams, Wesley B.

    2013-09-01

    Additive manufacturing technologies have the ability to directly produce parts with complex geometries without the need for secondary processes, tooling or fixtures. This ability was used to produce concave lapping tools with a VFlash 3D printer from 3D Systems. The lapping tools were first designed in Creo Parametric with a defined constant radius and radial groove pattern. The models were converted to stereolithography files which the VFlash used in building the parts, layer by layer, from a UV curable resin. The tools were rotated at 60 rpm and used with 120 grit and 220 grit silicon carbide lapping paste to lap 0.750" diameter fused silica workpieces. The samples developed a matte appearance on the lapped surface that started as a ring at the edge of the workpiece and expanded to the center. This indicated that as material was removed, the workpiece radius was beginning to match the tool radius. The workpieces were then cleaned and lapped on a second tool (with equivalent geometry) using a 3000 grit corundum aluminum oxide lapping paste, until a near specular surface was achieved. By using lapping tools that have been additively manufactured, fused silica workpieces can be lapped to approach a specified convex geometry. This approach may enable more rapid lapping of near net shape workpieces that minimize the material removal required by subsequent polishing. This research may also enable development of new lapping tool geometry and groove patterns for improved loose abrasive finishing.

  10. ADHESION OF AMORPHOUS CALCIUM PHOSPHATE COMPOSITES BONDED TO DENTIN: A STUDY IN FAILURE MODALITY

    PubMed Central

    O’Donnell, J.N.R.; Schumacher, G.E.; Antonucci, J.M.; Skrtic, D.

    2009-01-01

    Aims As a bioactive filler capable of remineralizing tooth structures, the main disadvantage of as-made amorphous calcium phosphate (am-ACP) are its large agglomerates. The objective of this study was to mill ACP, and compare the adhesive strength to dentin, work to fracture, and failure modes of both groups to glass-filled composites and one commercial compomer after 24 h, 1 week, 1, 3 and 6 months of exposure to simulated saliva solution (SLS). Flat dentin surfaces were acid-etched, primed, and photopolymerized. Composites were applied, photo-cured, and debonded in shear. The resin used in each composite was identical: ethoxylated bisphenol A dimethacrylate, triethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate and methacryloxyethyl phthalate. Fillers consisted of am-ACP and milled ACP (m-ACP), and a strontium-containing glass (Sr-glass) at respective mass fractions of (40, 60, and 75) %. Findings 90 % of the fracture surfaces in this study showed adhesive failure, with most of these occurring at the dentin/primer interface. 52 % of failures after 24 h immersion occurred at the primer/composite interface. After six months of SLS exposure, 80 % of specimens failed at the dentin/primer interface, with a 42 % overall reduction in bond strength. Conclusions Milled ACP composites showed initial mechanical advantages over am-ACP composites and the compomer, and produced a higher incidence of a failure mode consistent with stronger adhesion. Evidence is provided which suggests that milled ACP composites may offer enhanced potential in clinical bonding applications. PMID:19107798

  11. Bond strength of self-adhesive resin cements to different treated indirect composites.

    PubMed

    Fuentes, M Victoria; Ceballos, Laura; González-López, Santiago

    2013-04-01

    The objective of this study was to determine microtensile bond strength (μTBS) to dentin of three self-adhesive and a total-etch resin cements used for luting different treated indirect composites. Composite overlays (Filtek Z250) were prepared. Their intaglio surfaces were ground with 600-grit SiC papers and randomly assigned to three different surface treatments: no treatment, silane application (RelyX Ceramic Primer), and silane agent followed by a bonding agent (Adper Scotchbond 1 XT). The composite overlays were luted to flat dentin surfaces of extracted human third molars using the following self-adhesive resin cements: RelyX Unicem, Maxcem Elite and G-Cem, and a total-etch resin cement, RelyX ARC. The bonded assemblies were stored in water (24 h, 37 °C) and subsequently prepared for μTBS testing. Beams of approximately 1 mm(2) were tested in tension at 1 mm/min in a universal tester (Instron 3345). Data were analyzed by two-way ANOVA and Student-Newman-Keuls tests (α = 0.05). A significant influence of the resin cement used was detected. Composite surface treatment and the interaction between the resin cement applied and surface treatment did not affect μTBS. Surface treatment of indirect resin composite did not improve the μTBS results of dentin/composite overlay complex. Self-adhesive resin cements tested obtained lower μTBS than the total-etch resin cement RelyX ARC. Specimens luted with Maxcem Elite exhibited the highest percentage of pretesting failures. Surface treatment of indirect resin composite with silane or silane followed by a bonding agent did not affect bond strength to dentin.

  12. Temperature gradient measurements by using thermoelectric effect in CNTs-silicone adhesive composite.

    PubMed

    Chani, Muhammad Tariq Saeed; Karimov, Kh S; Asiri, Abdullah M; Ahmed, Nisar; Bashir, Muhammad Mehran; Khan, Sher Bahadar; Rub, Malik Abdul; Azum, Naved

    2014-01-01

    This work presents the fabrication and investigation of thermoelectric cells based on composite of carbon nanotubes (CNT) and silicone adhesive. The composite contains CNT and silicon adhesive 1∶1 by weight. The current-voltage characteristics and dependences of voltage, current and Seebeck coefficient on the temperature gradient of cell were studied. It was observed that with increase in temperature gradient the open circuit voltage, short circuit current and the Seebeck coefficient of the cells increase. Approximately 7 times increase in temperature gradient increases the open circuit voltage and short circuit current up to 40 and 5 times, respectively. The simulation of experimental results is also carried out; the simulated results are well matched with experimental results.

  13. Temperature Gradient Measurements by Using Thermoelectric Effect in CNTs-Silicone Adhesive Composite

    PubMed Central

    Chani, Muhammad Tariq Saeed; Karimov, Kh. S.; Asiri, Abdullah M.; Ahmed, Nisar; Bashir, Muhammad Mehran; Khan, Sher Bahadar; Rub, Malik Abdul; Azum, Naved

    2014-01-01

    This work presents the fabrication and investigation of thermoelectric cells based on composite of carbon nanotubes (CNT) and silicone adhesive. The composite contains CNT and silicon adhesive 1∶1 by weight. The current-voltage characteristics and dependences of voltage, current and Seebeck coefficient on the temperature gradient of cell were studied. It was observed that with increase in temperature gradient the open circuit voltage, short circuit current and the Seebeck coefficient of the cells increase. Approximately 7 times increase in temperature gradient increases the open circuit voltage and short circuit current up to 40 and 5 times, respectively. The simulation of experimental results is also carried out; the simulated results are well matched with experimental results. PMID:24748375

  14. Damage prognosis of adhesively-bonded joints in laminated composite structural components of unmanned aerial vehicles

    SciTech Connect

    Farrar, Charles R; Gobbato, Maurizio; Conte, Joel; Kosmatke, John; Oliver, Joseph A

    2009-01-01

    The extensive use of lightweight advanced composite materials in unmanned aerial vehicles (UAVs) drastically increases the sensitivity to both fatigue- and impact-induced damage of their critical structural components (e.g., wings and tail stabilizers) during service life. The spar-to-skin adhesive joints are considered one of the most fatigue sensitive subcomponents of a lightweight UAV composite wing with damage progressively evolving from the wing root. This paper presents a comprehensive probabilistic methodology for predicting the remaining service life of adhesively-bonded joints in laminated composite structural components of UAVs. Non-destructive evaluation techniques and Bayesian inference are used to (i) assess the current state of damage of the system and, (ii) update the probability distribution of the damage extent at various locations. A probabilistic model for future loads and a mechanics-based damage model are then used to stochastically propagate damage through the joint. Combined local (e.g., exceedance of a critical damage size) and global (e.g.. flutter instability) failure criteria are finally used to compute the probability of component failure at future times. The applicability and the partial validation of the proposed methodology are then briefly discussed by analyzing the debonding propagation, along a pre-defined adhesive interface, in a simply supported laminated composite beam with solid rectangular cross section, subjected to a concentrated load applied at mid-span. A specially developed Eliler-Bernoulli beam finite element with interlaminar slip along the damageable interface is used in combination with a cohesive zone model to study the fatigue-induced degradation in the adhesive material. The preliminary numerical results presented are promising for the future validation of the methodology.

  15. Near-Infrared Radiation Based Composite Repair Using Thermoplastics as Adhesives

    DTIC Science & Technology

    2007-12-01

    molding , which has been used for most of the thermoplastics described above. The first of five is a plain PA12 alloy, with no promoter. Within the...FINAL REPORT Near-Infrared Radiation Based Composite Repair Using Thermoplastics as Adhesives SERDP Project WP-1581 DECEMBER 2007 Dr...Using Thermoplastics as Adhesiveste 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER

  16. Adhesion of indirect MOD resin composite inlays luted with self-adhesive and self-etching resin cements.

    PubMed

    Inukai, T; Abe, T; Ito, Y; Pilecki, P; Wilson, R F; Watson, T F; Foxton, R M

    2012-01-01

    This study investigated the effect of loading on the bond strength to dentin and microleakage of MOD indirect composite restorations bonded with self-adhesive and self-etching resin cements with or without acid etching of the proximal enamel margins. Class II MOD cavities were prepared in 48 molar teeth into dentin and divided into three groups of 16 teeth. Impressions were taken and indirect composite inlays fabricated (Estenia C & B). The enamel margins of the proximal boxes of half the specimens were phosphoric acid etched, and the inlays were cemented with one of three cements (Panavia F 2.0, SA Cement, or Rely X Unicem). After luting, eight teeth in each cement group were mechanically loaded at 2.5 cycles/s for 250,000 cycles. Unloaded teeth acted as controls. Teeth were stored in Rhodamine B solution for 24 hours, sectioned buccolingually at the proximal boxes to examine microleakage using confocal microscopy, and further sectioned for μTBS testing of the resin-dentin interface. Analysis of variance was performed to assess the effect of loading and acid etching on microleakage and bond strength. Acid etching had no effect on microleakage. No significant difference in the dentin bond strengths between the three cements existed after loading. Panavia F 2.0 exhibited a significant reduction in bond strength. With regard to microleakage at the proximal boxes, loading had no effect on dye penetration at the cavity floor. However, at the axial walls, loading had a significant deleterious effect on Panavia F 2.0. No difference in microleakage existed between the three cements at both sites before and after loading. In conclusion, the two tested self-adhesive cements exhibited similar bond strengths before and after loading to the self-etching resin cement. Loading reduced dentin bond strengths and increased microleakage at the resin-dentin interface. However, acid etching of the enamel margins had no significant effect on microleakage in the approximal regions of

  17. Three-year Randomized Clinical Study of a One-step Universal Adhesive and a Two-step Self-etch Adhesive in Class II Composite Restorations.

    PubMed

    van Dijken, Jan Wv; Pallesen, Ulla

    2017-01-01

    To evaluate in a randomized clinical evaluation the 3-year clinical durability of a one-step universal adhesive and compare it intraindividually with a 2-step self-etch adhesive in Class II restorations. Each of 57 participants (mean age 58.3 years) received at least two extended Class II restorations that were as similar as possible. The cavities in each of the 60 individual pairs of cavities were randomly distributed to the 1-step universal adhesive (All-Bond Universal: AU) and the control 2-step self-etch adhesive (Optibond XTR: OX). A low shrinkage composite (Aelite LS) was used for all restorations, which were evaluated using slightly modified USPHS criteria at baseline and 1, 2, and 3 years. 114 Class II restorations were evaluated at three years. Eight restorations, 3 AU and 5 OX, failed during the follow-up, resulting in 94.7% (AU) and 91.2% (OX) success rates (p > 0.05). Annual failure rates were 1.8% and 2.9%, respectively.The main reason for failure was composite fracture. Class II composite restorations placed with a 1-step universal adhesive showed good short-term efficacy.

  18. Effect of intermediate adhesive resin and flowable resin application on the interfacial adhesion of resin composite to pre-impregnated unidirectional S2-glass fiber bundles.

    PubMed

    Polacek, Petr; Pavelka, Vladimir; Özcan, Mutlu

    2014-04-01

    This study evaluated the effect of either an intermediate application of adhesive resin or flowable resin application on the adhesion of particulate filler composite (PFC) to glass fiber-reinforced composite (FRC). Unidirectional, pre-impregnated S2-glass fiber bundles (Dentapreg) (length: 40 mm; thickness: 0.5 mm) were obtained (N = 30, n = 10 per group) and secured in translucent silicone material with the adhesion surface exposed and photopolymerized. They were randomly divided into 3 groups for the following adhesion sequence: A) FRC+PFC, B) FRC+intermediate adhesive resin+PFC, C) FRC+flowable resin+PFC. The PFC was applied in a polyethylene mold onto the FRC and photopolymerized. PFCs were debonded from the FRC surface using shear bond test in a universal testing machine (1 mm/min). After debonding, all specimens were analyzed using scanning electron microscopy to categorize the failure modes. The data were statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05). A significant difference was observed between the groups (p < 0.05). The highest mean bond strength value was obtained with the application of an intermediate layer of adhesive resin (group B: 19.4 ± 1.1 MPa) (p < 0.05) followed by group A (14.1 ± 0.6 MPa) and group C (10.4 ± 0.8 MPa), which were also significantly different from one another (p < 0.05). Group A exclusively presented a combination of partial cohesive failure in the PFC and adhesive failure between the FRC and PFC. While group B showed large cohesive defects in the FRC, in group C, only small cohesive failures were observed in the FRC. Based on the highest mean bond strength and the large cohesive failures within the FRC, application of an intermediate layer of adhesive resin on the S2-glass FRC surface prior to incremental build up of the PFC seems to be compulsory.

  19. Adhesion, layering, and finishing of resin composite restorations for class II cavity preparations.

    PubMed

    Ferraris, Federico

    2007-01-01

    The increasing knowledge of microhybrid composite materials has offered clinicians multiple restorative options. The use of products that guarantee a high adhesive capacity, isolation via rubber dam, and anatomic shaping with thin layering and adequate cyclic polymerization are the bases for a predictable result. Further, a finishing and polishing system that takes into account the superficial roughness and esthetic characteristics of the restorative material is the final element of a restoration that has been fabricated following correct treatment guidelines. This article aims to provide a protocol for the management of direct resin composite restorations and to discuss the correct operative sequence, particularly for the restoration of Class II cavity preparations.

  20. An investigation of adhesive/adherend and fiber/matrix interactions. Part B: SEM/ESCA analysis of fracture surfaces

    NASA Technical Reports Server (NTRS)

    Beck, B.; Widyani, E.; Wightman, J. P.

    1983-01-01

    Adhesion was studied with emphasis on the characterization of surface oxide layers, the analysis of fracture surfaces, and the interaction of matrices and fibers. A number of surface features of the fractured lap shear samples were noted in the SEM photomicrographs including the beta phase alloy of the Ti 6-4 adherend, the imprint of the adherend on the adhesive failure surface, increased void density for high temperature samples, and the alumina filler particles. Interfacial failure of some of the fractured lap shear samples is invariably characterized by the appearance of an ESCA oxygen photopeak at 530.3 eV assigned to the surface oxide layer of Ti 6-4 adherend. The effect of grit blasting on carbon fiber composites is evident in the SEM analysis. A high surface fluorine concentration on the composite surface is reduced some ten fold by grit blasting.

  1. How Tongue Size and Roughness Affect Lapping

    NASA Astrophysics Data System (ADS)

    Hubbard, M. J.; Hay, K. M.

    2012-10-01

    The biomechanics of domestic cat lapping (Felis catus) and domestic dog lapping (Canis familiaris) is currently under debate. Lapping mechanics in vertebrates with incomplete cheeks, such as cats and dogs, is a balance of inertia and the force of gravity likely optimized for ingestion and physical necessities. Physiology dictates vertebrate mass, which dictates vertebrate tongue size, which dictates lapping mechanics to achieve optimum liquid ingestion; with either touch lapping, scooping, or a hybrid lapping method. The physics of this optimized system then determines how high a column of liquid can be raised before it collapses due to gravity, and therefore, lapping frequency. Through tongue roughness model variation experiments it was found that pore-scale geometrical roughness does not appear to affect lapping or liquid uptake. Through tongue size model variation experiments it was found that there is a critical tongue radius in the range of 25 mm to 35 mm above which touch lapping is no longer an efficient way to uptake liquid. Vertebrates with incomplete cheeks may use a touch lapping method to ingest water if their tongue radius is less than this critical radius and use an alternative ingestion method if their tongue radius is larger.

  2. The effect of different adhesives and setting times on bond strength between Biodentine and composite.

    PubMed

    Çolak, Hakan; Tokay, Uğur; Uzgur, Recep; Uzgur, Zeynep; Ercan, Ertuğrul; Hamidi, Mehmet M

    2016-05-18

    The aim of this study was to evaluate the effects of 3 different adhesives with different functional monomers, on the shear bond strength (SBS) of Biodentine®. Acrylic blocks (n = 90) were prepared and a 2-mm height x 4-mm diameter hole was opened in each block. Every hole was completely restored with Biodentine®. Before preparation of composite restorations over the Biodentine® (2-mm height x 2-mm diameter), 3 different adhesives (Etch-37 (37%) w/BAC by Bisco & Prime Bond N&T, Clearfil S3 Bond and Adper Prompt L-Pop) were applied. SBS was evaluated using a universal testing machine, and failure mode for each sample was recorded. The results were statistically analyzed using 2-way ANOVA and post hoc Tukey test. When the megapascal values of all groups were compared, although there was no statistically significant difference in the different setting times (p>0.05), statistically significant differences were observed among all adhesive groups (p<0.05). Moreover, the highest SBS values were observed in the Clearfil S3 Bond group. Clinical performance of Biodentine® may be affected by adhesive procedures and its setting time.

  3. Investigation of adhesive properties of dental composite materials using an improved tensile test procedure and scanning electron microscopy.

    PubMed

    Rider, M; Tanner, A N; Kenny, B

    1977-04-01

    A standardized tension test was used to evaluate the adhesive properties of several composite materials when used on both dentin and enamel specimens. The nature of the test surfaces was examined by roughness tests using a Talysurf machine and also in more detail by means of a scanning electron microscope. Poor results were obtained for the adhesion of composite materials to dentin whereas good retention to enamel was obtained.

  4. Ultrasonic Evaluation of Thermal Degradation in Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Lih, Shyh-Shiuh; Mal, Ajit K.; Bar-Cohen, Yoseph

    1994-01-01

    The critical role played by adhesive bonds in lap joints is well known. A good knowledge of the mechanical properties of adhesive bonds in lap joints is a prerequisite to the design and reliable prediction of the performance of these bonded structures. Furthermore, the lap joint may be subject to high-temperature environments in service. Early detection of the degree of thermal degradation in adhesive bonds is required under these circumstances. A variety of ultrasonic nondestructive evaluation (NDE) techniques can be used to determine the thickness and the elastic moduli of adhesively bonded joints. In this paper we apply a previously developed technique based on the leaky Lamb wave (LLW) experiment to investigate the possibility of characterizing the thermal degradation of adhesive bonds in lap joints. The degradation of the adhesive bonds is determined through comparison between experimental data and theoretical calculations.

  5. The effect of elastin on chondrocyte adhesion and proliferation on poly (ɛ-caprolactone)/elastin composites.

    PubMed

    Annabi, Nasim; Fathi, Ali; Mithieux, Suzanne M; Martens, Penny; Weiss, Anthony S; Dehghani, Fariba

    2011-02-01

    The aim of this study was to demonstrate the effect of elastin on chondrocyte adhesion and proliferation within the structure of poly (ɛ-caprolactone) (PCL)/elastin composites. The homogenous 3D structure composites were constructed by using high pressure CO(2) in two stages. Porous PCL structures with average pore sizes of 540 ± 21 μm and a high degree of interconnectivity were produced using gas foaming/salt leaching. The PCL scaffolds were then impregnated with elastin and cross-linked with glutaraldehyde (GA) under high pressure CO(2). The effects of elastin and cross-linker concentrations on the characteristics of composites were investigated. Increasing the elastin concentration from 25mg/ml to 100mg/ml elevated the amount of cross-linked elastin inside the macropores of PCL. Fourier transform infrared (FTIR) analysis showed that elastin was homogeneously distributed throughout the 3D structure of all composites. The weight gain of composites increased 2-fold from 15.8 ± 0.3 to 38.3 ± 0.7 (w/w) % by increasing the elastin concentration from 25mg/ml to 50mg/ml and approached a plateau above this concentration. The presence of elastin within the pores of PCL improved the water uptake properties of PCL scaffolds; the water uptake ratio of PCL was enhanced 100-fold from 0.030 ± 0.005g liquid/g polymer to 11.80 ± 0.01g liquid/g polymer, when the elastin solution concentration was 50mg/ml. These composites exhibited lower compressive modulus and energy loss compared to pure PCL scaffolds due to their higher water content and elasticity. In vitro studies show that these composites can support primary articular cartilage chondrocyte adhesion and proliferation within the 3D structures. These results demonstrate the potential of using PCL/elastin composites for cartilage repair.

  6. Effects of barrier composition and electroplating chemistry on adhesion and voiding in copper/dielectric diffusion barrier films

    SciTech Connect

    Birringer, Ryan P.; Dauskardt, Reinhold H.; Shaviv, Roey; Geiss, Roy H.; Read, David T.

    2011-08-15

    The effects of electroplating chemistry and dielectric diffusion barrier composition on copper voiding and barrier adhesion are reported. Adhesion was quantified using the four-point bend thin film adhesion technique, and voiding in the Cu films was quantified using scanning electron microscopy. A total of 12 different film stacks were investigated, including three different Cu electroplating chemistries and four different barrier materials (SiN, N-doped SiC, O-doped SiC, and dual-layer SiC). Both plating chemistry and barrier composition have a large effect on interface adhesion and voiding in the Cu film. X-ray photoelectron spectroscopy was used to investigate the segregation of Cu electroplating impurities, such as S and Cl, to the Cu/barrier interface. Secondary ion mass spectrometry was used to quantify oxygen content at the Cu/barrier interface in a subset of samples. This interface oxygen content is correlated with measured adhesion values.

  7. A critical examination of stresses in an elastic single lap joint

    NASA Technical Reports Server (NTRS)

    Cooper, P. A.; Sawyer, J. W.

    1979-01-01

    The results of an approximate nonlinear finite-element analysis of a single lap joint are presented and compared with the results of a linear finite-element analysis, and the geometric nonlinear effects caused by the load-path eccentricity on the adhesive stress distributions are determined. The results from finite-element, Goland-Reissner, and photoelastic analyses show that for a single lap joint the effect of the geometric nonlinear behavior of the joint has a sizable effect on the stresses in the adhesive. The Goland-Reissner analysis is sufficiently accurate in the prediction of stresses along the midsurface of the adhesive bond to be used for qualitative evaluation of the influence of geometric or material parametric variations. Detailed stress distributions in both the adherend and adhesive obtained from the finite-element analysis are presented to provide a basis for comparison with other solution techniques.

  8. Effect of curing unit and adhesive system on marginal adaptation of composite restorations.

    PubMed

    Casselli, Denise Sa Maia; Faria-e-Silva, Andre Luis; Casselli, Henrique; Martins, Luis Roberto Marcondes

    2012-01-01

    This study sought to evaluate how a curing unit and adhesive system affected the marginal adaptation of resin composite restorations. Class V cavities were prepared in bovine teeth with a gingival margin in dentin and an incisal margin in enamel. The cavities were restored with a micro-hybrid resin composite using one of four adhesives: Single Bond 2, Prime & Bond NT, Clearfil SE Bond, Xeno IV. The light-activations were performed using a quartz-tungsten-halogen (QTH) lamp or a second-generation light-emitting diode (LED). Restorations were finished and polished and epoxy replicas were prepared. Marginal adaptation was analyzed by using scanning electronic microscopy (magnification 500X). The widest gaps in each margin were recorded, and data were submitted to Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests (α = 0.05). Differences between the adhesives were observed only when the dentin margins were evaluated: Clearfil SE Bond demonstrated better marginal adaptation than Prime & Bond NT or Single Bond 2 (which demonstrated the widest gaps in the dentin margin). The type of curing unit only affected the results for Xeno IV when the enamel margin was analyzed; the LED lamp promoted smaller gaps than the QTH lamp.

  9. Adhesive bond strength evaluation in composite materials by laser-generated high amplitude ultrasound

    NASA Astrophysics Data System (ADS)

    Perton, M.; Blouin, A.; Monchalin, J.-P.

    2011-01-01

    Adhesive bonding of composites laminates is highly efficient but is not used for joining primary aircraft structures, since there is presently no nondestructive inspection technique to ensure the quality of the bond. We are developing a technique based on the propagation of high amplitude ultrasonic waves to evaluate the adhesive bond strength. Large amplitude compression waves are generated by a short pulse powerful laser under water confinement and are converted after reflection by the assembly back surface into tensile waves. The resulting tensile stresses can cause a delamination inside the laminates or at the bond interfaces. The adhesion strength is evaluated by increasing the laser pulse energy until disbond. A good bond is unaffected by a certain level of stress whereas a weaker one is damaged. The method is shown completely non invasive throughout the whole composite assembly. The sample back surface velocity is measured by an optical interferometer and used to estimate stress history inside the sample. The depth and size of the disbonds are revealed by a post-test inspection by the well established laser-ultrasonic technique. Experimental results show that the proposed method is able to differentiate weak bond from strong bonds and to estimate quantitatively their bond strength.

  10. Contemporary adhesives: marginal adaptation and microtensile bond strength of class II composite restorations.

    PubMed

    Takahashi, Rena; Nikaido, Toru; Tagami, Junji; Hickel, Reinhard; Kunzelmann, Karl-Heinz

    2012-06-01

    To evaluate the marginal adaptation (in terms of % continuous margin) and microtensile bond strength (microTBS) of the enamel and dentin of direct class II composite restorations. 32 standardized class II cavities were prepared with the gingival margin of one box occlusal to the cementum-enamel junction (CEJ) and one gingival floor extended beyond the CEJ. The teeth (n= 8) were restored using one of four adhesive systems [Adper Scotchbond Multi Purpose (SMPP), Adper Scotchbond 1 XT (S1XT), Clearfil SE Bond (CSEB), or Clearfil Tri-S Bond (CTSB)] with incrementally placed composite restorations before being stored in water (24 hours), thermocycled (2,000 cycles, 5 to 55 degrees C) and mechanically loaded (50,000 cycles, 50 N). Marginal adaptation was evaluated by SEM. Additionally, the teeth were sectioned and trimmed to obtain specimens for microTBS testing. All adhesive systems exhibited "continuous margins" in enamel over 95.4%, whereas "continuous margins" in dentin ranged from 60.2 to 84.8%. CSEB and CTSB yielded significantly more "continuous margins" between the adhesive restoration and dentin than SMPP or S1XT (P< 0.05). The mean microTBSs (MPa) for enamel were 40.5 (SMPP), 37.3 (S1XT), 30.8 (CSEB) and 23.2 (CTSB), and for dentin, they were 37.7 (SMPP), 33.0 (S1XT), 37.3 (CSEB) and 29.0 (CTSB).

  11. Changes in membrane sphingolipid composition modulate dynamics and adhesion of integrin nanoclusters

    PubMed Central

    Eich, Christina; Manzo, Carlo; Keijzer, Sandra de; Bakker, Gert-Jan; Reinieren-Beeren, Inge; García-Parajo, Maria F.; Cambi, Alessandra

    2016-01-01

    Sphingolipids are essential constituents of the plasma membrane (PM) and play an important role in signal transduction by modulating clustering and dynamics of membrane receptors. Changes in lipid composition are therefore likely to influence receptor organisation and function, but how this precisely occurs is difficult to address given the intricacy of the PM lipid-network. Here, we combined biochemical assays and single molecule dynamic approaches to demonstrate that the local lipid environment regulates adhesion of integrin receptors by impacting on their lateral mobility. Induction of sphingomyelinase (SMase) activity reduced sphingomyelin (SM) levels by conversion to ceramide (Cer), resulting in impaired integrin adhesion and reduced integrin mobility. Dual-colour imaging of cortical actin in combination with single molecule tracking of integrins showed that this reduced mobility results from increased coupling to the actin cytoskeleton brought about by Cer formation. As such, our data emphasizes a critical role for the PM local lipid composition in regulating the lateral mobility of integrins and their ability to dynamically increase receptor density for efficient ligand binding in the process of cell adhesion. PMID:26869100

  12. Tooth bleaching effects 
on the adhesive interface 
of composite restorations.

    PubMed

    Silva, Lorena; Thedei, Geraldo; Menezes-Oliveira, Maria Angélica; Nogueira, Ruchele D; Geraldo-Martins, Vinicius

    2017-01-01

    The objective of this study was to evaluate the effects of different bleaching techniques on the tooth-restoration interface of composite restorations. Cavities (3 x 3 x 2 mm) were prepared in 100 bovine incisor fragments, which were etched with a conventional adhesive system and restored with a nanocomposite. The fragments were randomly divided into five groups (n = 20): Control (no bleaching), At-home bleaching (HB) (10% hydrogen peroxide [HP]), In-office bleaching (OB) (35% HP), LED-activated bleaching (LB) (35% HP activated by LED), and Laser-activated bleaching (LaB) (35% HP activated by diode laser, λ = 880 nm). After bleaching, 10 samples per group were thermocycled (500 cycles, 5°C to 55°C), immersed in 50% silver nitrate solution, sectioned, evaluated under a stereomicroscope, and scored for microleakage. The other samples were pH cycled for 14 consecutive days, sectioned, and the enamel adjacent to the adhesive interface assessed by cross-sectional Knoop hardness. The data were compared using the one-way ANOVA (α = 0.05). No differences between the microleakage indexes found for the control and experimental groups were observed. The enamel of the bleached groups located near the adhesive interface presented the same Knoop hardness numbers as the samples of the control group. Tooth bleaching does not damage the tooth-restoration interface of composite restorations.

  13. Designing heterogeneous chemical composition on hierarchical structured copper substrates for the fabrication of superhydrophobic surfaces with controlled adhesion.

    PubMed

    Cheng, Zhongjun; Hou, Rui; Du, Ying; Lai, Hua; Fu, Kewei; Zhang, Naiqing; Sun, Kening

    2013-09-11

    Controlling water adhesion is important for superhydrophobic surfaces in many applications. Compared with numerous researches about the effect of microstructures on the surface adhesion, research relating to the influence of surface chemical composition on the surface adhesion is extremely rare. Herein, a new strategy for preparation of tunable adhesive superhydrophobic surfaces through designing heterogeneous chemical composition (hydrophobic/hydrophilic) on the rough substrate is reported, and the influence of surface chemical composition on the surface adhesion are examined. The surfaces were prepared through self-assembling of mixed thiol (containing both HS(CH2)9CH3 and HS(CH2)11OH) on the hierarchical structured copper substrates. By simply controlling the concentration of HS(CH2)11OH in the modified solution, tunable adhesive superhydrophobic surfaces can be obtained. The adhesive force of the surfaces can be increased from extreme low (about 8 μN) to very high (about 65 μN). The following two reasons can be used to explain the tunable effect: one is the number of hydrogen bond for the variation of surface chemical composition; and the other is the variation of contact area between the water droplet and surface because of the capillary effect that results from the combined effect of hydrophilic hydroxyl groups and microstructures on the surface. Noticeably, water droplets with different pH (2-12) have similar contact angles and adhesive forces on the surfaces, indicating that these surfaces are chemical resistant to acid and alkali. Moreover, the as-prepared surfaces were also used as the reaction substrates and applied in the droplet-based microreactor for the detection of vitamin C. This report provides a new method for preparation of superhydrophobic surfaces with tunable adhesion, which could not only help us further understand the principle for the fabrication of tunable adhesive superhydrophobic surfaces, but also potentially be used in many

  14. In situ synthesis of mesoporous polyvinyl alcohol/hydroxyapatite composites for better biomedical coating adhesion

    NASA Astrophysics Data System (ADS)

    Hussain, Riaz; Tabassum, Sobia; Gilani, Mazhar Amjad; Ahmed, Ejaz; Sharif, Ahsan; Manzoor, Faisal; Shah, Asma Tufail; Asif, Anila; Sharif, Faiza; Iqbal, Farasat; Siddiqi, Saadat Anwar

    2016-02-01

    Hydroxyapatite (HA) shows diverse biomedical applications as bone filler and coating material for metal implants to enhance osteoconduction. Four different PVAHA composites were synthesized in situ by an economical co-precipitation wet methodology. The FTIR spectra of PVAHA composites showed characteristic signals of HA and PVA. The BET surface area of PVAHA composites were in range of 41.3-63.7 m2/g. The composites showed type IV nitrogen adsorption/desorption isotherm, a characteristic for mesoporous material. The pore diameter range (6.3-8.1 nm) of PVAHA composites also confirmed their mesoporous nature. The Barrett-Joyner-Halenda (BJH) pore size distribution curves indicated a narrow pore size distribution. To obtain a homogeneous crack free coating with EPD on stainless steel (SS) plates, different parameters such as PVA percentages in PVAHA composites, solvent, deposition time and voltage were optimized. The PVAHA composites were stable after EPD as confirmed by FTIR spectra recorded before and after EPD. The SEM images of the coating showed a homogeneous morphology. The thickness of the coating was controlled by varying voltage and time. The best results were obtained with c-PVAHA composite at 30 volts for 5-10 min and current density was around 4.5 to 5 mA. The adhesion strength of c-PVAHA coating was measured by using ASTM standard F1044-99. The average value was approximately 9.328 ± 1.58 MPa.

  15. Repairs of composite structures

    NASA Astrophysics Data System (ADS)

    Roh, Hee Seok

    Repair on damaged composite panels was conducted. To better understand adhesively bonded repair, the study investigates the effect of design parameters on the joint strength. The design parameters include bondline length, thickness of adherend and type of adhesive. Adhesives considered in this study were tested to measure their tensile material properties. Three types of adhesively bonded joints, single strap, double strap, and single lap joint were considered under changing bondline lengths, thickness of adherend and type of adhesive. Based on lessons learned from bonded joints, a one-sided patch repair method for composite structures was conducted. The composite patch was bonded to the damaged panel by either film adhesive FM-73M or paste adhesive EA-9394 and the residual strengths of the repaired specimens were compared under varying patch sizes. A new repair method using attachments has been suggested to enhance the residual strength. Results obtained through experiments were analyzed using finite element analysis to provide a better repair design and explain the experimental results. It was observed that the residual strength of the repaired specimen was affected by patch length. Method for rapid repairs of damaged composite structures was investigated. The damage was represented by a circular hole in a composite laminated plate. Pre-cured composite patches were bonded with a quick-curing commercial adhesive near (rather than over) the hole. Tensile tests were conducted on specimens repaired with various patch geometries. The test results showed that, among the methods investigated, the best repair method restored over 90% of the original strength of an undamaged panel. The interfacial stresses in the adhesive zone for different patches were calculated in order to understand the efficiencies of the designs of these patch repairs. It was found that the composite patch that yielded the best strength had the lowest interfacial peel stress between the patch and

  16. A Study on the Structure and Adhesive Properties of Epoxy-Silicate Composites

    NASA Astrophysics Data System (ADS)

    Brantseva, T. V.; Ilyin, S. O.; Gorbunova, I. Yu.; Antonov, S. V.; Kerber, M. L.

    2014-11-01

    Compositions based on an ED-20 resin with three types of modifiers: natural montmorillonite (MMT) Cloisite Na +, organomodified MMT Cloisite 30B, and halloysite, were investigated. An optimum regime was chosen for preparation of the epoxy/modifier systems by employing the ultrasonic mixing. The rheological characteristics of suspensions were used to estimate the distribution of modifier in the epoxy oligomer. According to rheological data, the best dispersion of MMT in the epoxy oligomer after ultrasonic stirring was observed for the organomodified MMT Cloisite 30B. The maximum shear adhesion strength was also observed for the epoxy resin+Cloisite 30B systems. For the systems with 2 wt. % of Cloisite 30B, the increase in the adhesion strength was up to 65% as compared with that of the pristine epoxy oligomer.

  17. Characterization of debond growth mechanism in adhesively bonded composites under mode II static and fatigue loadings

    NASA Technical Reports Server (NTRS)

    Mall, S.; Kochhar, N. K.

    1988-01-01

    An experimental investigation of adhesively bonded composite joint was conducted to characterize the debond growth mechanism under mode II static and fatigue loadings. For this purpose, end-notched flexure specimens of graphite/epoxy (T300/5208) adherends bonded with EC 3445 adhesive were tested. In all specimen tested, the fatigue failure occurred in the form of cyclic debonding. The present study confirmed the result of previous studies that total strain-energy-release rate is the driving parameter for cyclic debonding. Further, the debond growth resistance under cyclic loading with full shear reversal (i.e., stress ratio, R = -1) is drastically reduced in comparison to the case when subjected to cyclic shear loading with no shear reversal (i.e., R = 0.1).

  18. Composite generalized Langevin equation for Brownian motion in different hydrodynamic and adhesion regimes.

    PubMed

    Yu, Hsiu-Yu; Eckmann, David M; Ayyaswamy, Portonovo S; Radhakrishnan, Ravi

    2015-05-01

    We present a composite generalized Langevin equation as a unified framework for bridging the hydrodynamic, Brownian, and adhesive spring forces associated with a nanoparticle at different positions from a wall, namely, a bulklike regime, a near-wall regime, and a lubrication regime. The particle velocity autocorrelation function dictates the dynamical interplay between the aforementioned forces, and our proposed methodology successfully captures the well-known hydrodynamic long-time tail with context-dependent scaling exponents and oscillatory behavior due to the binding interaction. Employing the reactive flux formalism, we analyze the effect of hydrodynamic variables on the particle trajectory and characterize the transient kinetics of a particle crossing a predefined milestone. The results suggest that both wall-hydrodynamic interactions and adhesion strength impact the particle kinetics.

  19. Loose abrasive slurries for optical glass lapping

    SciTech Connect

    Neauport, Jerome; Destribats, Julie; Maunier, Cedric; Ambard, Chrystel; Cormont, Philippe; Pintault, B.; Rondeau, Olivier

    2010-10-20

    Loose abrasive lapping is widely used to prepare optical glass before its final polishing. We carried out a comparison of 20 different slurries from four different vendors. Slurry particle sizes and morphologies were measured. Fused silica samples were lapped with these different slurries on a single side polishing machine and characterized in terms of surface roughness and depth of subsurface damage (SSD). Effects of load, rotation speed, and slurry concentration during lapping on roughness, material removal rate, and SSD were investigated.

  20. Reduction of bacterial adhesion on dental composite resins by silicon-oxygen thin film coatings.

    PubMed

    Mandracci, Pietro; Mussano, Federico; Ceruti, Paola; Pirri, Candido F; Carossa, Stefano

    2015-01-29

    Adhesion of bacteria on dental materials can be reduced by modifying the physical and chemical characteristics of their surfaces, either through the application of specific surface treatments or by the deposition of thin film coatings. Since this approach does not rely on the use of drugs or antimicrobial agents embedded in the materials, its duration is not limited by their possible depletion. Moreover it avoids the risks related to possible cytotoxic effects elicited by antibacterial substances released from the surface and diffused in the surrounding tissues. In this work, the adhesion of Streptococcus mutans and Streptococcus mitis was studied on four composite resins, commonly used for manufacturing dental prostheses. The surfaces of dental materials were modified through the deposition of a-SiO(x) thin films by plasma enhanced chemical vapor deposition. The chemical bonding structure of the coatings was analyzed by Fourier-transform infrared spectroscopy. The morphology of the dental materials before and after the coating deposition was assessed by means of optical microscopy and high-resolution mechanical profilometry, while their wettability was investigated by contact angle measurements. The sample roughness was not altered after coating deposition, while a noticeable increase of wettability was detected for all the samples. Also, the adhesion of S. mitis decreased in a statistically significant way on the coated samples, when compared to the uncoated ones, which did not occur for S. mutans. Within the limitations of this study, a-SiO(x) coatings may affect the adhesion of bacteria such as S. mitis, possibly by changing the wettability of the composite resins investigated.

  1. Bond strength evaluation of three self-adhesive luting systems used for cementing composite and porcelain.

    PubMed

    De Angelis, F; Minnoni, A; Vitalone, L M; Carluccio, F; Vadini, M; Paolantonio, M; D'Arcangelo, C

    2011-01-01

    Self-adhesive resin cements were recently introduced with the purpose of simplifying the cementation technique, as they combine the use of adhesive and cement in a single application, eliminating the need for pretreatment of the tooth. In the present study a microtensile bond strength test (μ-TBS) was used to compare three self-adhesives, an etch-and-rinse and a self-etch luting system, in the cementation of resin-based composite (RBC) and ceramic disks to dentin. Freshly extracted molars were transversally sectioned to expose flat, deep dentin surfaces. Cylindrical specimens (5 mm in diameter and 10 mm in height), consisting of RBC disks and leucite-based glass ceramic disks, were produced. The RBC disks were sandblasted with 50-μm Al2O3. The ceramic disks were conditioned with 9.5% hydrofluoric acid gel and silane application. All of the disks were then bonded to dentin surfaces employing five different luting agents: iCEM Self Adhesive (Heraeus Kulzer), MaxCem (Kerr Corporation), RelyX UniCem (3M ESPE), EnaCem HF (Micerium), and Panavia F2.0 (Kuraray-Dental). The products were applied according to the manufacturers' instructions. The specimens were sectioned perpendicular to the adhesive interface to produce multiple beams measuring approximately 1 mm2 in cross section. For each experimental group 12 beams were tested. The preterm failures were also taken into account. All of the specimen preparations were performed by the same operator. The beams were tested under tension at a crosshead speed of 0.5 mm/min until failure. Mean μ-TBS values were calculated for each group. Data were analyzed by a two-way analysis of variance, and multiple comparisons were performed using a Tukey test (α=0.05). The UniCem group showed the lowest number of preterm failures among the tested self-adhesive systems. When premature debondings were included in the mean value calculation, bond strength values for the UniCem group were statistically equal to or even higher than those

  2. Female inheritance of malarial lap genes is essential for mosquito transmission.

    PubMed

    Raine, J Dale; Ecker, Andrea; Mendoza, Jacqui; Tewari, Rita; Stanway, Rebecca R; Sinden, Robert E

    2007-03-01

    Members of the LCCL/lectin adhesive-like protein (LAP) family, a family of six putative secreted proteins with predicted adhesive extracellular domains, have all been detected in the sexual and sporogonic stages of Plasmodium and have previously been predicted to play a role in parasite-mosquito interactions and/or immunomodulation. In this study we have investigated the function of PbLAP1, 2, 4, and 6. Through phenotypic analysis of Plasmodium berghei loss-of-function mutants, we have demonstrated that PbLAP2, 4, and 6, as previously shown for PbLAP1, are critical for oocyst maturation and sporozoite formation, and essential for transmission from mosquitoes to mice. Sporozoite formation was rescued by a genetic cross with wild-type parasites, which results in the production of heterokaryotic polyploid ookinetes and oocysts, and ultimately infective Deltapblap sporozoites, but not if the individual Deltapblap parasite lines were crossed amongst each other. Genetic crosses with female-deficient (Deltapbs47) and male-deficient (Deltapbs48/45) parasites show that the lethal phenotype is only rescued when the wild-type pblap gene is inherited from a female gametocyte, thus explaining the failure to rescue in the crosses between different Deltapblap parasite lines. We conclude that the functions of PbLAPs1, 2, 4, and 6 are critical prior to the expression of the male-derived gene after microgametogenesis, fertilization, and meiosis, possibly in the gametocyte-to-ookinete period of differentiation. The phenotypes detectable by cytological methods in the oocyst some 10 d after the critical period of activity suggests key roles of the LAPs or LAP-dependent processes in the regulation of the cell cycle, possibly in the regulation of cytoplasm-to-nuclear ratio, and, importantly, in the events of cytokinesis at sporozoite formation. This phenotype is not seen in the other dividing forms of the mutant parasite lines in the liver and blood stages.

  3. Micro-measurements of mechanical properties for adhesives and composites using digital imaging technology

    NASA Technical Reports Server (NTRS)

    Brinson, Hal F.

    1994-01-01

    The need for a constituent based durability or accelerated life prediction procedure to be used for the engineering design of polymer matrix composites is discussed in the light of current plans for the High Speed Civil Transport (HSCT) concerns about the U.S. infrastructure (bridges, pipelines, etc.) and other technological considerations of national concern. It is pointed out that good measurement procedures for insitu resin properties are needed for both adhesives and composites. A double cantilever beam (DCB) specimen which shows promise for the easy determination of adhesive shear properties is presented and compared with measurements of strains within the bondline using a new optical digital imaging micro-measurement system (DIMMS). The DCB specimen is also used to assess damage in a bonded joint using a dynamic mechanical thermal analysis system (DMTA). The possible utilization of the same DIMMS and DMTA procedures to determine the insitu properties of the resin in a composite specimen are discussed as well as the use of the procedures to evaluate long term mechanical and physical aging. Finally, a discussion on the state-of-the art of the measurement of strains in micron and sub-micron domains is given.

  4. One-year clinical evaluation of composite restorations in posterior teeth: effect of adhesive systems.

    PubMed

    Sundfeld, R H; Scatolin, R S; Oliveira, F G; Machado, L S; Alexandre, R S; Sundefeld, M L M M

    2012-01-01

    This clinical study assessed the performance of posterior composite resins applied with the Adper™ Single Bond Plus (SB) and Adper™ Scotchbond SE (SE) adhesive systems and Filtek™ Supreme Plus composite resin, using modified US Public Health Service criteria. A total of 97 restorations were placed in posterior teeth by two calibrated operators. Application of the materials followed manufacturers' instructions. The restorations were evaluated by two examiners at baseline and after one year. Statistical analyses were conducted using the proportion test at a significance level of 5% (p<0.05). All the restorations evaluated (ie, 100%) received an alpha rating for the criteria of marginal discoloration and marginal integrity at baseline. At one year, for marginal discoloration, 64.6% of SB and 61.2% of SE received an alpha rating. For marginal integrity, 72.9% of SB and 77.6% of SE received an alpha rating. The other restorations received bravo ratings for both criteria. None of the teeth that received the restorative systems presented caries lesions around the restorations. A total of eight teeth presented postoperative sensitivity one week after baseline, five with SB and three with SE; the symptom had disappeared one year later. One year later, composite resin restorations using either adhesive system showed satisfactory clinical performance.

  5. Bacterial immobilization by adhesion onto agave-fiber/polymer foamed composites.

    PubMed

    Robledo-Ortíz, J R; Ramírez-Arreola, D E; Gomez, C; González-Reynoso, O; González-Núñez, R

    2010-02-01

    Adhesion of Pseudomonas putida F1 onto agave-fiber/recycled-polyethylene foamed composites was studied under different controlled conditions. The adhesion process was analyzed in batch experiments controlling factors such as pH, contact time, temperature, initial biomass concentration and ionic strength; and was verified by scanning electron microscopy (SEM). The number of adhered bacteria after the experimental time was determined by difference between concentration of suspended cells in NaCl solution contained in two different Erlenmeyer flasks, one of the flasks with composite pellets and the other one without them. The concentration of cells in each flask was obtained using the serial dilution technique. Experimental data analysis showed that adsorption follows first-order kinetics. And it was further corroborated to be an irreversible process. For the first time, an equation is proposed here to predict the correlation between adhered bacteria and aqueous pH. In addition to the obvious reuse of waste material, these results suggested that agave-fiber/polymer foamed composites could be used as support for bacterial immobilization to be applied, among others in environmental processes such as bioremediation and biofiltration of gases with almost limitless possibilities.

  6. Shear bond strengths of composite to dentin using six dental adhesive systems.

    PubMed

    Triolo, P T; Swift, E J; Barkmeier, W W

    1995-01-01

    The development of adhesive agents for bonding composite to dentin has rapidly evolved in recent years. It is postulated that dentin bond strengths in the range of 17 MPa are sufficient to resist the polymerization shrinkage of composite resins. The purpose of this study was to evaluate the shear bond strengths of the following dentin adhesive systems: All-Bond 2 (Bisco), Imperva Bond (Shofu), Optibond (Kerr), Permagen (Ultradent), ProBond (Caulk/Dentsply), and Scotchbond Multi-Purpose (3M). Sixty human molars (10 per group) were mounted in phenolic rings, and the occlusal surfaces were flat ground in dentin to 600 grit. The prepared dentin bonding sites were treated according to the directions for each of the systems evaluated. A gelatin capsule technique was used to bond Bis-Fil composite cylinders to the teeth. The specimens were stored in water at 37 degrees C for 24 hours. Mean shear bond strengths were as follows: Scotchbond Multi-Purpose: 23.1 +/- 2.6 MPa, All-Bond 2: 21.4 +/- 7.8 MPa, Imperva Bond: 19.8 +/- 6.1 MPa, Optibond: 19.7 +/- 3.6 MPa, ProBond: 16.3 +/- 4.5 MPa, and Permagen: 16.2 +/- 3.0 MPa. There was not a significant difference (P<0.05) in the bond strengths of Scotchbond Multi-Purpose, All-Bond 2, Imperva Bond, and Optibond. The bond strengths of Scotchbond Multi-Purpose and All-Bond 2 were significantly greater (P<0.05) than ProBond and Permagen. Current-generation dentin adhesive systems have approached or exceeded the theoretical threshold value to resist contraction stresses during polymerization of resin materials.

  7. Effect of Curing Mode on Shear Bond Strength of Self-Adhesive Cement to Composite Blocks

    PubMed Central

    Kim, Jin-Young; Cho, Ga-Young; Roh, Byoung-Duck; Shin, Yooseok

    2016-01-01

    To overcome the disadvantages of computer-aided design/computer-aided manufacturing (CAD/CAM) processed indirect restorations using glass-ceramics and other ceramics, resin nano ceramic, which has high strength and wear resistance with improved polish retention and optical properties, was introduced. The purpose of this study was to evaluate the shear bond strength and fracture pattern of indirect CAD/CAM composite blocks cemented with two self-etch adhesive cements with different curing modes. Sand-blasted CAD/CAM composite blocks were cemented using conventional resin cement, Rely X Ultimate Clicker (RXC, 3M ESPE, St. Paul, MN, USA) with Single Bond Universal (SB, 3M ESPE, St. Paul, MN, USA) for the control group or two self-adhesive resin cements: Rely X U200 (RXU, 3M ESPE, St. Paul, MN, USA) and G-CEM Cerasmart (GC, GC corporation, Tokyo, Japan). RXU and GC groups included different curing modes (light-curing (L) and auto-curing (A)). Shear bond strength (SBS) analyses were performed on all the specimens. The RXC group revealed the highest SBS and the GC A group revealed the lowest SBS. According to Tukey’s post hoc test, the RXC group showed a significant difference compared to the GC A group (p < 0.05). For the curing mode, RXU A and RXU L did not show any significant difference between groups and GC A and GC L did not show any significant difference either. Most of the groups except RXC and RXU L revealed adhesive failure patterns predominantly. The RXC group showed a predominant cohesive failure pattern in their CAD/CAM composite, LavaTM Ultimate (LU, 3M ESPE, St. Paul, MN, USA). Within the limitations of this study, no significant difference was found regarding curing modes but more mixed fracture patterns were showed when using the light-curing mode than when using the self-curing mode. PMID:28773334

  8. Microleakage of class V resin composites using various self-etching adhesives: an in vitro study.

    PubMed

    Chandra, P V Ravi; Harikumar, V; Ramkiran, D; Krishna, M J N; Gouda, M Veerabhadra

    2013-01-01

    Microleakage has been identified as a significant problem with composite restorations because of interfacial gap formation which can result in tooth discoloration, recurrent caries, possible pulpal involvement and restoration replacement. Aim of this study is to evaluate the microleakage of self-etch adhesive system at the coronal and apical margins of class V resin composite restorations under stereomicroscope at 20× magnification. Class V cavities were prepared on the facial surfaces of 48 human premolars with coronal margins located in enamel and apical margins located in dentin. Teeth were divided into four groups: Group one-Xeno V; group two- G-Bond; group three-Clearfil S(3) Bond; group four-control. After application of bonding agent and restoration, the teeth were subjected to thermocycling. The teeth were then immersed in 1% aqueous solution of methylene blue dye for 24 hours and sectioned to allow the assessment of microleakage under microscope. Coronal and apical margins were scored separately using a 0-3 ordinal ranking system and the recorded values were statistically analyzed using Kruskal-Wallis, Mann- Whitney U-test and Wilcoxon signed rank test. Statistical analysis showed that there was less microleakage in Xeno V at coronal region and Clearfil S(3) Bond in apical region, overall Clearfil S(3) Bond showed less marginal permeability in both coronal and apical regions. Specimens restored with the Xeno V and Clearfil S(3) Bond adhesive systems revealed reduced leakage at the coronal margin. At the apical margin, Xeno V showed greater leakage than the other groups, except the control. In class V restorations restored with composite resin, the choice of material affects the microleakage and retention of the restoration. This study theorizes that the self-etch adhesives show less microleakage in the coronal area than the apical margin.

  9. Adhesive Wear Performance of CFRP Multilayered Polyester Composites Under Dry/wet Contact Conditions

    NASA Astrophysics Data System (ADS)

    Danaelan, D.; Yousif, B. F.

    The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0-0.6 km) at different sliding velocities (0.1-0.28 m/s). The effect of applied load and sliding velocity was evaluated. The results showed that all test parameters have significant influence on friction and wear characteristics of the composites. Moreover, friction coefficient increased as the normal load and speed increased, the values were about 0.7-0.9 under dry contact condition. Meanwhile, under wet contact condition, there was a great reduction in the friction coefficient, i.e. the values were about 0.1-0.2. Furthermore, the specific wear rates were found to be around 2-4 (10-3) mm3/Nm under dry contact condition and highly reduced under wet condition. In other words, the presence of water as cleaner and polisher assisted to enhance the adhesive wear performance of CFRP by about 10%. The images from optical microscope showed evidence of adhesive wear mode with transition to abrasive wear mode at higher sliding velocities due to third body abrasion. On the other hand, optical images for wet condition showed less adhesive wear and smooth surfaces.

  10. Bacterial adhesion on direct and indirect dental restorative composite resins: An in vitro study on a natural biofilm.

    PubMed

    Derchi, Giacomo; Vano, Michele; Barone, Antonio; Covani, Ugo; Diaspro, Alberto; Salerno, Marco

    2017-05-01

    Both direct and indirect techniques are used for dental restorations. Which technique should be preferred or whether they are equivalent with respect to bacterial adhesion is unclear. The purpose of this in vitro study was to determine the affinity of bacterial biofilm to dental restorative composite resins placed directly and indirectly. Five direct composite resins for restorations (Venus Diamond, Adonis, Optifil, Enamel Plus HRi, Clearfil Majesty Esthetic) and 3 indirect composite resins (Gradia, Estenia, Signum) were selected. The materials were incubated in unstimulated whole saliva for 1 day. The biofilms grown were collected and their bacterial cells counted. In parallel, the composite resin surface morphology was analyzed with atomic force microscopy. Both bacterial cell count and surface topography parameters were subjected to statistical analysis (α=.05). Indirect composite resins showed significantly lower levels than direct composite resins for bacterial cell adhesion, (P<.001). No significant differences were observed within the direct composite resins (P>.05). However, within the indirect composite resins a significantly lower level was found for Gradia than Estenia or Signum (P<.01). A partial correlation was observed between composite resin roughness and bacterial adhesion when the second and particularly the third-order statistical moments of the composite resin height distributions were considered. Indirect dental restorative composite resins were found to be less prone to biofilm adhesion than direct composite resins. A correlation of bacterial adhesion to surface morphology exists that is described by kurtosis; thus, advanced data analysis is required to discover possible insights into the biologic effects of morphology. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  11. Synthesis and characterization of high temperature curable poly(arylene ether) structural adhesive and composite matrices

    SciTech Connect

    Mecham, S.J.; Jayaraman, S.; Bobbitt, M.M.

    1996-12-31

    Crosslinked poly(arylene ether) systems are projected to display many desirable properties suitable for aerospace structural adhesive and composite matrix applications. The synthesis and characterization of a series of processable high temperature curing poly(arylene ether) oligomers incorporating terminally reactive phenylethynyl endgroups will be discussed. Characterization of the oligomers includes NMR, intrinsic viscosity, parallel plate rheological behavior, TGA, and DSC. Curing of these oligomers was conducted at or above 380{degrees}C, providing a large processing window. Thermal stability is very good and the melt viscosity of the oligomers in the processing temperature range is exceptionally low.

  12. Influence of Interface Gap on the Stress Behaviour of Smart Single Lap Joints Under Time Harmonic Load

    NASA Astrophysics Data System (ADS)

    Ivanova, Jordanka; Valeva, Varbinka

    2017-06-01

    Adhesive joints are frequently used in different composite structures due to their improved mechanical performance and better understanding of the failure mechanics. The application of such structures can be seen in aerospace and high technology components. The authors developed and applied modified shear lag analysis to investigate the hygrothermalpiezoelectric response of a smart single lap joint at environmental conditions (with/without an interface gap along the overlap zone) and under dynamic time harmonic mechanical and electric loads. The main key is the study of the appearance of possible delamination along the interface. As illustrative examples, the analytical closed form solution of the structure shear and the axial stresses response, as well as the interface debond length, including influence of mechanical, piezoelectric, thermal characteristics and frequencies is performed and discussed. All results are presented in figures. The comparison of the shear stress and electric fields for both cases of overlap zone (continuous or with a gap) is also shown in figures and discussed.

  13. Petrography of Lunar Meteorite LAP 02205, a New Low-Ti Basalt Possibly Launch Paired with NWA 032

    NASA Technical Reports Server (NTRS)

    Jolliff, B. L.; Zeigler, R. A.; Korotev, R. L.

    2004-01-01

    Lunar meteorite LAP 02205 is a 1.23 kg basalt collected during the 2002 field season in the La- Paz ice field, Antarctica [1]. We present a petrographic description including mineral modes and compositions, and the major-element composition of the bulk meteorite. LAP 02205 is an Fe-rich, moderately low-Ti mare basalt that is similar in composition, mineralogy, and mineral chemistry to the NWA 032 basaltic lunar meteorite. LAP 02205 is yet another of the moderately low- Ti basaltic meteorites that are underrepresented among Apollo and Luna samples but that appear from remote sensing to be the most common basalt type on the Moon.

  14. Develop, demonstrate, and verify large area composite structural bonding with polyimide adhesives. [adhesively bonding graphite-polyimide structures

    NASA Technical Reports Server (NTRS)

    Bhombal, B. D.; Wykes, D. H.; Hong, K. C.; Stenersen, A. A.

    1982-01-01

    The technology required to produce graphite-polyimide structural components with operational capability at 598 K (600 F) is considered. A series of polyimide adhesives was screened for mechanical and physical properties and processibility in fabricating large midplane bonded panels and honeycomb sandwich panels in an effort to fabricate a structural test component of the space shuttle aft body flap. From 41 formulations, LaRC-13, FM34B-18, and a modified LaRC-13 adhesive were selected for further evaluation. The LaRC-13 adhesive was rated as the best of the three adhesives in terms of availability, cost, processibility, properties, and ability to produce void fee large area (12" x 12") midplane bonds. Surface treatments and primers for the adhesives were evaluated and processes were developed for the fabrication of honeycomb sandwich panels of very good quality which was evidenced by rupture in the honeycomb core rather than in the facesheet bands on flatwise tensile strength testing. The fabrication of the adhesively bonded honeycomb sandwich cover panels, ribs, and leading edge covers of Celion graphite/LARC-160 polyimide laminates is described.

  15. Impact of head and neck radiotherapy on the mechanical behavior of composite resins and adhesive systems: A systematic review.

    PubMed

    Madrid Troconis, Cristhian Camilo; Santos-Silva, Alan Roger; Brandão, Thaís Bianca; Lopes, Marcio Ajudarte; de Goes, Mario Fernando

    2017-08-08

    To analyze the evidence regarding the impact of head and neck radiotherapy (HNRT) on the mechanical behavior of composite resins and adhesive systems. Searches were conducted on PubMed, Embase, Scopus and ISI Web of Science databases using "Radiotherapy", "Composite resins" and "Adhesive systems" as keywords. Selected studies were written in English and assessed the mechanical behavior of composite resins and/or adhesive systems when bonding procedure was conducted before and/or after a maximum radiation dose ≥50Gy, applied under in vitro or in vivo conditions. In total, 115 studies were found but only 16 were included, from which five evaluated the effect of in vitro HNRT on microhardness, wear resistance, diametral tensile and flexural strength of composite resins, showing no significant negative effect in most of reports. Regarding bond strength of adhesive systems, 11 studies were included from which five reported no meaningful negative effect when bonding procedure was conducted before simulated HNRT. Conversely, five studies showed that bond strength diminished when adhesive procedure was done after in vitro radiation therapy. Only two studies about dental adhesion were conducted after in vivo radiotherapy but the results were not conclusive. The mechanical behavior of composite resins and adhesive systems seems not to be affected when in vitro HNRT is applied after bonding procedure. However, bond strength of adhesive systems tends to decrease when simulated radiotherapy is used immediately before bonding procedure. Studies assessing dentin bond strength after in-vivo HNRT were limited and controversial. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Continuous fiber reinforced composite materials as alternatives for metal alloys used for dental appliances.

    PubMed

    Karmaker, A C; DiBenedetto, A T; Goldberg, A J

    1997-01-01

    Two types of uniaxially oriented long S2-glass fiber reinforced composites were prepared for use in various dental appliances. Matrix polymers were polycarbonate (PC) and bisphenol A bis (2-hydroxy-propyl) methacrylate (Bis-GMA) based copolymers. Flexural tests were conducted on the composites using a procedure which simulates clinical usages. To evaluate the adhesion between the composites and the adhesive, the single-lap shear test was conducted. Mechanical properties of the small cross-sectional composite strips were superior to those used previously in clinical studies.

  17. Sealing of adhesive systems in ferric sulfate-contaminated dentinal margins in class V composite resin restorations

    PubMed Central

    Shadman, Niloofar; Farzin Ebrahimi, Shahram; Mollaie, Najmeh

    2016-01-01

    Background. Hemostatic agents are applied to prepare an isolated bleeding-free condition during dental treatments and can influence adhesive restorations. This study evaluated the effect of a hemostatic agent (ViscoStat) on microleakage of contaminated dentinal margin of class V composite resin restorations with three adhesives. Methods. Sixty freshly extracted human molars were selected and class V cavities (3×3×1.5 mm) were prepared on buccal and lingual surfaces. Gingival margins of the cavities were placed below the cementoenamel junction. The teeth were divided into six groups randomly. The adhesives were Excite, AdheSE and AdheSE One. In three groups, the gingival walls of the cavities were contaminated with ViscoStat and then rinsed. The cavities were restored with composite resin and light-cured. After storage in distilled water (37°C) for 24 hours and polishing, the samples were thermocycled and sealed with nail varnish. Then they were stored in 1% basic fuchsin for 24 hours, rinsed and mounted in self-cured acryl resin, followed by sectioning buccolingually. Dye penetration was observed under a stereomicroscope and scored. Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests. P<0.05 was set as the level of significance. Results. Only in the Excite group, contamination did not have adverse effects on dentin microleakage (P > 0.05). In the contaminated groups, Excite had significantly less microleakage than the others (P = 0.003). AdheSE and AdheSE One did not exhibit significant difference in microleakage (P > 0.05). Conclusion. ViscoStat hemostatic agent increased dentinal microleakage in AdheSE and AdheSE One adhesives with no effect on Excite. PMID:27092210

  18. Sealing of adhesive systems in ferric sulfate-contaminated dentinal margins in class V composite resin restorations.

    PubMed

    Shadman, Niloofar; Farzin Ebrahimi, Shahram; Mollaie, Najmeh

    2016-01-01

    Background. Hemostatic agents are applied to prepare an isolated bleeding-free condition during dental treatments and can influence adhesive restorations. This study evaluated the effect of a hemostatic agent (ViscoStat) on microleakage of contaminated dentinal margin of class V composite resin restorations with three adhesives. Methods. Sixty freshly extracted human molars were selected and class V cavities (3×3×1.5 mm) were prepared on buccal and lingual surfaces. Gingival margins of the cavities were placed below the cementoenamel junction. The teeth were divided into six groups randomly. The adhesives were Excite, AdheSE and AdheSE One. In three groups, the gingival walls of the cavities were contaminated with ViscoStat and then rinsed. The cavities were restored with composite resin and light-cured. After storage in distilled water (37°C) for 24 hours and polishing, the samples were thermocycled and sealed with nail varnish. Then they were stored in 1% basic fuchsin for 24 hours, rinsed and mounted in self-cured acryl resin, followed by sectioning buccolingually. Dye penetration was observed under a stereomicroscope and scored. Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests. P<0.05 was set as the level of significance. Results. Only in the Excite group, contamination did not have adverse effects on dentin microleakage (P > 0.05). In the contaminated groups, Excite had significantly less microleakage than the others (P = 0.003). AdheSE and AdheSE One did not exhibit significant difference in microleakage (P > 0.05). Conclusion. ViscoStat hemostatic agent increased dentinal microleakage in AdheSE and AdheSE One adhesives with no effect on Excite.

  19. [In vitro study of marginal microleakage of Clearfil S3 BOND adhesive systems and Majesty composite resin].

    PubMed

    Wang, Bei; Zhu, Ya-qin

    2009-08-01

    To evaluate the microleakage of standard box-type cavity filled with Clearfil S3 BOND self-etch adhesive systems and Majesty composite resin. 40 permanent molars were randomly divided into experimental and control groups, 20 of each . The box-type cavities, 3mm in length and width and 2mm in depth, were prepared at the cemento-enamel junction on buccal surface of forty permanent extracted teeth. According to grouping, the experimental group was filled with Clearfil S(3) BOND self-adhesive systems and Majesty composite resin, and the control group was filled with 3M Adper Prompt self-adhesive and Filtek Z350 composite resin. After thermal circulation(2000 times, 5 degrees centigrade-55 degrees centigrade) and soaked for 24 hours in 2% methyl blue solution, the samples were cut through the midline of the restoration and the leakage depth was measured with vernier caliper. The microleakage degrees and microleakage depth of 2 groups were analyzed with SPSS 17.0 software package for Mann-Whitney U test and independent-samples t test. Microleakage was observed in both groups. But the microleakage degrees and microleakage depth of 2 groups had no significant difference (P>0.05). The marginal sealibility of Clearfil S(3) BOND self-adhesive systems and Majesty composite resin is as good as Adper Prompt self-adhesive and Filtek Z350 composite resin,it may be an ideal clinical restoration material.

  20. Shear bond strength of composite bonded with three adhesives to Er,Cr:YSGG laser-prepared enamel.

    PubMed

    Türkmen, Cafer; Sazak-Oveçoğlu, Hesna; Günday, Mahir; Güngör, Gülşad; Durkan, Meral; Oksüz, Mustafa

    2010-06-01

    To assess in vitro the shear bond strength of a nanohybrid composite resin bonded with three adhesive systems to enamel surfaces prepared with acid and Er,Cr:YSGG laser etching. Sixty extracted caries- and restoration-free human maxillary central incisors were used. The teeth were sectioned 2 mm below the cementoenamel junction. The crowns were embedded in autopolymerizing acrylic resin with the labial surfaces facing up. The labial surfaces were prepared with 0.5-mm reduction to receive composite veneers. Thirty specimens were etched with Er,Cr:YSGG laser. This group was also divided into three subgroups, and the following three bonding systems were then applied on the laser groups and the other three unlased groups: (1) 37% phosphoric acid etch + Bond 1 primer/adhesive (Pentron); (2) Nano-bond self-etch primer (Pentron) + Nano-bond adhesive (Pentron); and (3) all-in-one adhesive-single dose (Futurabond NR, Voco). All of the groups were restored with a nanohybrid composite resin (Smile, Pentron). Shear bond strength was measured with a Zwick universal test device with a knife-edge loading head. The data were analyzed with two-factor ANOVA. There were no significant differences in shear bond strength between self-etch primer + adhesive and all-in-one adhesive systems for nonetched and laser-etched enamel groups (P > .05). However, bond strength values for the laser-etched + Bond 1 primer/adhesive group (48.00 +/- 13.86 MPa) were significantly higher than the 37% phosphoric acid + Bond 1 primer/adhesive group (38.95 +/- 20.07 MPa) (P < .05). The Er,Cr:YSGG laser-powered hydrokinetic system etched the enamel surface more effectively than 37% phosphoric acid for subsequent attachment of composite material.

  1. Prediction of fracture toughness and durability of adhesively bonded composite joints with undesirable bonding conditions

    NASA Astrophysics Data System (ADS)

    Musaramthota, Vishal

    Advanced composite materials have enabled the conventional aircraft structures to reduce weight, improve fuel efficiency and offer superior mechanical properties. In the past, materials such as aluminum, steel or titanium have been used to manufacture aircraft structures for support of heavy loads. Within the last decade or so, demand for advanced composite materials have been emerging that offer significant advantages over the traditional metallic materials. Of particular interest in the recent years, there has been an upsurge in scientific significance in the usage of adhesively bonded composite joints (ABCJ's). ABCJ's negate the introduction of stress risers that are associated with riveting or other classical techniques. In today's aircraft transportation market, there is a push to increase structural efficiency by promoting adhesive bonding to primary joining of aircraft structures. This research is focused on the issues associated with the durability and related failures in bonded composite joints that continue to be a critical hindrance to the universal acceptance of ABCJ's. Of particular interest are the short term strength, contamination and long term durability of ABCJ's. One of the factors that influence bond performance is contamination and in this study the influence of contamination on composite-adhesive bond quality was investigated through the development of a repeatable and scalable surface contamination procedure. Results showed an increase in the contaminant coverage area decreases the overall bond strength significantly. A direct correlation between the contaminant coverage area and the fracture toughness of the bonded joint was established. Another factor that influences bond performance during an aircraft's service life is its long term strength upon exposure to harsh environmental conditions or when subjected to severe mechanical loading. A test procedure was successfully developed in order to evaluate durability of ABCJ's comprising severe

  2. Bonding and nondestructive evaluation of graphite/PEEK composite and titanium adherends with thermoplastic adhesives

    NASA Technical Reports Server (NTRS)

    Hodges, W. T.; Tyeryar, J. R.; Berry, M.

    1985-01-01

    Bonded single overlap shear specimens were fabricated from Graphite/PEEK (Polyetheretherketone) composite adherends and titanium adherends. Six advanced thermoplastic adhesives were used for the bonding. The specimens were bonded by an electromagnetic induction technique producing high heating rates and high-strength bonds in a few minutes. This contrasts with conventionally heated presses or autoclaves that take hours to process comparable quality bonds. The Graphite/PEEK composites were highly resistant to delamination during the testing. This allowed the specimen to fail exclusively through the bondline, even at very high shear loads. Nondestructive evaluation of bonded specimens was performed ultrasonically by energizing the entire thickness of the material through the bondline and measuring acoustic impedance parameters. Destructive testing confirmed the unique ultrasonic profiles of strong and weak bonds, establishing a standard for predicting relative bond strength in subsequent specimens.

  3. Ultrasonic, microwave, and millimeter wave inspection techniques for adhesively bonded stacked open honeycomb core composites

    NASA Astrophysics Data System (ADS)

    Thomson, Clint D.; Cox, Ian; Ghasr, Mohammad Tayeb Ahmed; Ying, Kuang P.; Zoughi, Reza

    2015-03-01

    Honeycomb sandwich composites are used extensively in the aerospace industry to provide stiffness and thickness to lightweight structures. A common fabrication method for thick, curved sandwich structures is to stack and bond multiple honeycomb layers prior to machining core curvatures. Once bonded, each adhesive layer must be inspected for delaminations and the presence of unwanted foreign materials. From a manufacturing and cost standpoint, it can be advantageous to inspect the open core prior to face sheet closeout in order to reduce end-article scrap rates. However, by nature, these honeycomb sandwich composite structures are primarily manufactured from low permittivity and low loss materials making detection of delamination and some of the foreign materials (which also are low permittivity and low loss) quite challenging in the microwave and millimeter wave regime. Likewise, foreign materials such as release film in adhesive layers can be sufficiently thin as to not cause significant attenuation in through-transmission ultrasonic signals, making them difficult to detect. This paper presents a collaborative effort intended to explore the efficacy of different non-contact NDI techniques for detecting flaws in a stacked open fiberglass honeycomb core panel. These techniques primarily included air-coupled through-transmission ultrasonics, single-sided wideband synthetic aperture microwave and millimeter-wave imaging, and lens-focused technique. The goal of this investigation has been to not only evaluate the efficacy of these techniques, but also to determine their unique advantages and limitations for evaluating parameters such as flaw type, flaw size, and flaw depth.

  4. Molar fracture resistance after adhesive restoration with ceramic inlays or resin-based composites.

    PubMed

    Bremer, B D; Geurtsen, W

    2001-08-01

    To determine the fracture resistance of teeth, following treatment with various types of adhesive restorations. 5 0 caries-free, extracted human molars were randomly divided into five groups consisting of 10 molars each. MOD cavities were prepared in 40 molars with a width in the facio-lingual direction of 50% of the intercuspal distances. The cavities were filled with the following materials: Cerec or IPS Empress ceramic inlays, Arabesk or Charisma F resin-based composite (RBC) restorations. The control group consisted of 10 sound, non-restored molars. All 50 teeth were loaded occlusally until fracture using a tensile testing machine. The statistical analysis included ANOVA, Kolmogorov-Smimov-test, Scheffé test, and boxplots. There was no significant difference (P > 0.05) between the mean values of the sound teeth (2,102 N) and the teeth with the Cerec ceramic inlays (2,139 N). However, both groups demonstrated a significant difference (P < 0.05) when compared with the teeth with IPS Empress ceramic inlays (1,459 N) and Arabesk RBC restorations (1459 N). No significant differences were found between the last two groups. Molars restored with Charisma F composite restorations (1,562 N) revealed no significant difference when compared with all other groups including controls (P > 0.05). A stabilization of molars is possible by means of an adhesive restoration in the form of an "internal splinting" regardless of the restorative material used.

  5. Atomic force and super-resolution microscopy support a role for LapA as a cell-surface biofilm adhesin of Pseudomonas fluorescens

    PubMed Central

    Ivanov, Ivan E.; Boyd, Chelsea D.; Newell, Peter D.; Schwartz, Mary E.; Turnbull, Lynne; Johnson, Michael S.; Whitchurch, Cynthia B.; O’Toole, George A.; Camesano, Terri A.

    2012-01-01

    Pseudomonas fluorescence Pf0-1 requires the large repeat protein LapA for stable surface attachment. This study presents direct evidence that LapA is a cell-surface-localized adhesin. Atomic force microscopy (AFM) revealed a significant twofold reduction in adhesion force for mutants lacking the LapA protein on the cell surface compared to the wild-type strain. Deletion of lapG, a gene encoding a periplasmic cysteine protease that functions to release LapA from the cell surface, resulted in a twofold increase in the force of adhesion. Three-dimensional structured illumination microscopy (3D-SIM) revealed the presence of the LapA protein on the cell surface, consistent with its role as an adhesin. The protein is only visualized in the cytoplasm for a mutant of the ABC transporter responsible for translocating LapA to the cell surface. Together, these data highlight the power of combining the use of AFM and 3D-SIM with genetic studies to demonstrate that LapA, a member of a large group of RTX-like repeat proteins, is a cell-surface adhesin. PMID:23064158

  6. How dogs lap: ingestion and intraoral transport in Canis familiaris.

    PubMed

    Crompton, A W; Musinsky, Catherine

    2011-12-23

    It has recently been suggested that the mechanism for lifting liquid from a bowl into the oral cavity during lapping is fundamentally different in cats and dogs: cats use adhesion of liquid to the tongue tip while dogs 'scoop' with their backwardly curled tongue. High-speed light videos and X-ray videos show that on the contrary, both cats and dogs use the mechanism of adhesion. Liquid is transported through the oral cavity to the oesophagus, against gravity, on the surface of the tongue as it is drawn upwards, then a tight contact between the tongue surface and palatal rugae traps liquid and prevents its falling out as the tongue is protruded. At least three cycles are needed for intraoral transport of liquid in the dog.

  7. Fatigue strength of a single lap joint SPR-bonded

    NASA Astrophysics Data System (ADS)

    Di Franco, G.; Fratini, L.; Pasta, A.

    2011-05-01

    In the last years, hybrid joints, meaning with this the joints which consist in combining a traditional mechanical joint to a layer of adhesive, are gradually attracting the attention of various sectors of the construction of vehicles and transportation industries, for their better performance compared to just mechanical joints (self-piercing riveting SPR, riveting, and so on) or just to bonded joints. The paper investigates the fatigue behavior of a single lap joint self-piercing riveted (SPR) and bonded throughout fatigue tests. The considered geometric configuration allowed the use of two rivets placed longitudinally; an epoxy resin was used as adhesive. In the first part of the work static characterization of the joints was carried out through tensile tests. Then fatigue tests were made with the application of different levels of load. The fatigue curves were also obtained at the varying the distance between the two rivets in order to better assess the joint strength for a given length of overlap.

  8. Decreased astroglial cell adhesion and proliferation on zinc oxide nanoparticle polyurethane composites

    PubMed Central

    Seil, Justin T; Webster, Thomas J

    2008-01-01

    Nanomaterials offer a number of properties that are of interest to the field of neural tissue engineering. Specifically, materials that exhibit nanoscale surface dimensions have been shown to promote neuron function while simultaneously minimizing the activity of cells such as astrocytes that inhibit central nervous system regeneration. Studies demonstrating enhanced neural tissue regeneration in electrical fields through the use of conductive materials have led to interest in piezoelectric materials (or those materials which generate a transient electrical potential when mechanically deformed) such as zinc oxide (ZnO). It has been speculated that ZnO nanoparticles possess increased piezoelectric properties over ZnO micron particles. Due to this promise in neural applications, the objective of the present in vitro study was, for the first time, to assess the activity of astroglial cells on ZnO nanoparticle polymer composites. ZnO nanoparticles embedded in polyurethane were analyzed via scanning electron microscopy to evaluate nanoscale surface features of the composites. The surface chemistry was characterized via X-ray photoelectron spectroscopy. Astroglial cell response was evaluated based on cell adhesion and proliferation. Astrocyte adhesion was significantly reduced on ZnO nanoparticle/polyurethane (PU) composites with a weight ratio of 50:50 (PU:ZnO) wt.%, 75:25 (PU:ZnO) wt.%, and 90:10 (PU:ZnO) wt.% in comparison to pure PU. The successful production of ZnO nanoparticle composite scaffolds suitable for decreasing astroglial cell density demonstrates their potential as a nerve guidance channel material with greater efficiency than what may be available today. PMID:19337420

  9. Micro-Energy Rates for Damage Tolerance and Durability of Composite Structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Minnetyan, Levon

    2006-01-01

    In this paper, the adhesive bond strength of lap-jointed graphite/aluminum composites is examined by computational simulation. Computed micro-stress level energy release rates are used to identify the damage mechanisms associated with the corresponding acoustic emission (AE) signals. Computed damage regions are similarly correlated with ultrasonically scanned damage regions. Results show that computational simulation can be used with suitable NDE methods for credible in-service monitoring of composites.

  10. In vitro effect of Paullinia cupana (guaraná) on hydrophobicity, biofilm formation, and adhesion of Candida albicans' to polystyrene, composites, and buccal epithelial cells.

    PubMed

    Matsuura, Ermelinda; Godoy, Janine Silva Ribeiro; Bonfim-Mendonça, Patrícia de Souza; de Mello, João Carlos Palazzo; Svidzinski, Terezinha Inez Estivalet; Gasparetto, André; Maciel, Sandra Mara

    2015-03-01

    In vitro evaluation of the effect of guaraná (GUAR) on cell surface hydrophobicity (CSH), on biofilm formation, and on adhesion of C. albicans to polystyrene, to composite resins, and to buccal epithelial cells (BEC). Lyophilised aqueous extract of GUAR was tested on C. albicans ATCC (90028). The effect of GUAR was evaluated by examining the CSH of C. albicans, as determined by microbial adhesion to hydrocarbons test, by assessing biofilm production and through adhesion assays (microplates of polystyrene, BEC and composites). One nanoparticle (Z350(®)) and two microhybrid (LLis(®), Opallis(®)) composites were tested. Scanning electron microscopy (SEM) was used to analyse adhesion of C. albicans composites. Assays were performed in triplicate and the results analysed by Chi-square test, Kruskal-Wallis test and Dunn's Multiple Comparison post hoc test at 5% significance level. GUAR did not inhibit growth of C. albicans at any concentration, but it reduced adhesion to polystyrene surface (p < 0.001). Exposure to GUAR did not change CSH and biofilm formation, but it increased adhesion of C. albicans to the nanoparticle composite (p = 0.042) and reduced its adhesion to BEC (p < 0.001). SEM confirmed an aggregatory pattern of adhesion of C. albicans to composites. GUAR increased the adhesion of C. albicans to the surface of the nanoparticle composite. However, it reduced the adhesion of C. albicans to BEC and to polystyrene, which reveals its potential use in prevention of oral diseases. Copyright © 2014. Published by Elsevier Ltd.

  11. Nondestructive Evaluation of Adhesive Bonds via Ultrasonic Phase Measurements

    NASA Technical Reports Server (NTRS)

    Haldren, Harold A.; Perey, Daniel F.; Yost, William T.; Cramer, K. Elliott; Gupta, Mool C.

    2016-01-01

    The use of advanced composites utilizing adhesively bonded structures offers advantages in weight and cost for both the aerospace and automotive industries. Conventional nondestructive evaluation (NDE) has proved unable to reliably detect weak bonds or bond deterioration during service life conditions. A new nondestructive technique for quantitatively measuring adhesive bond strength is demonstrated. In this paper, an ultrasonic technique employing constant frequency pulsed phased-locked loop (CFPPLL) circuitry to monitor the phase response of a bonded structure from change in thermal stress is discussed. Theoretical research suggests that the thermal response of a bonded interface relates well with the quality of the adhesive bond. In particular, the effective stiffness of the adhesive-adherent interface may be extracted from the thermal phase response of the structure. The sensitivity of the CFPPLL instrument allows detection of bond pathologies that have been previously difficult-to-detect. Theoretical results with this ultrasonic technique on single epoxy lap joint (SLJ) specimens are presented and discussed. This technique has the potential to advance the use of adhesive bonds - and by association, advanced composite structures - by providing a reliable method to measure adhesive bond strength, thus permitting more complex, lightweight, and safe designs.

  12. Transverse Reinforcement of Adhesive Joints

    NASA Astrophysics Data System (ADS)

    Sapozhnikov, S.; Shakirov, A.

    2015-05-01

    The shear of single-lap adhesive joints causes significant peel stresses in the adhesive layer, which is a particularly urgent problem for low-modulus polyurethane compositions. An experimental and computational analysis of various methods for increasing the load-bearing capacity of the joints by their strengthening with metallic z-elements was carried out. This strengthening hinders their delamination by the action of peel stresses, which allows one to reduce the overall dimensions and weight of adhesive joints. Two main strengthening methods were considered: with steel tapping screws (of diameter 2.5 mm) and blind aluminum rivets (of diameter 4.0 mm). The peculiarity of the strengthening lies in the fact that z-elements of minimum available diameter were used for reducing the effect of stress concentrations on the strength of the joints. The test of specimens for each type of strengthening showed an average increase in the ultimate load by 40% for the threaded reinforcements and by 10% for the rivets. During an analysis of stress state of the joints by the FEM, the nonlinear behavior of constituent materials and stress concentration in the region of reinforcing elements were taken into account. The mechanical properties of the adhesive layer and the GFRP covering were determined in separate experiments. The analysis showed that the weight of the reinforced adhesive joints could be lowered by 20-25% relative to that of unreinforced ones without reducing their load-bearing capacity. An additional effect caused by using the threaded reinforcing elements was a more than threefold increase in their rigidity as compared with that of analogous nonreinforced ones.

  13. Acetylene-terminated polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Hanky, A. O.

    1983-01-01

    The nadic-encapped LARC-13 addition polyimide exhibits excellent flow, is easy to process, and can be utilized for short terms at temperatures up to 593 C. It retains good lap shear strength as an adhesive for titanium after aging in air up to 125 hours at 316 C; but lap shear strength degrades with longer exposures at that temperature. Thermid 600, an addition polyimide that is acetylene encapped, exhibits thermomechanical properties even after long term exposure in at air at 316 C. An inherent drawback of this system is that it has a narrow processing window. An acetylene encapped, addition polyimide which is a hybrid of these two systems was developed. It has good retention of strength after long term aging and is easily processed. The synthesis and characterization of various molecular weight oligomers of this system are discussed as well as the bonding, aging, and testing of lap shear adhesive samples.

  14. Seam bonding of graphite reinforced composite panels

    NASA Technical Reports Server (NTRS)

    Buckley, John D.; Fox, Robert L.; Tyeryar, James R.

    1986-01-01

    An account is given of the design features and operating characteristics of a method for the joining of composite parts, at a rate of 2 to 6 inches/min, in which the heating process responsible for adhesive flow at 800 F is focused upon the overlapped seam. The heating element is a self-tuning solid state power oscillator whose ferrite's toroid geometry generates a uniform, concentrated magnetic flux in the component to be bonded. Specimens cut from graphite/epoxy panels bonded with epoxy-phenolic adhesive by this process have exhibited average lap-shear strengths of the order of 3400 lbs/sq in.

  15. Composites containing albumin protein or cyanoacrylate adhesives and biodegradable scaffolds: I. Acute wound closure study in a rat model

    NASA Astrophysics Data System (ADS)

    Hoffman, Grant T.; Soller, Eric C.; Heintzelman, Douglas L.; Duffy, Mark T.; Bloom, Jeffrey N.; Gilmour, Travis M.; Gonnerman, Krista N.; McNally-Heintzelman, Karen M.

    2004-07-01

    Composite adhesives composed of biodegradable scaffolds impregnated with a biological or synthetic adhesive were investigated for use in wound closure as an alternative to using either one of the adhesives alone. Two different scaffold materials were investigated: (i) a synthetic biodegradable material fabricated from poly(L-lactic-co-glycolic acid); and (ii) a biological material, small intestinal sub mucosa, manufactured by Cook BioTech. The biological adhesive was composed of 50%(w/v) bovine serum albumin solder and 0.5mg/ml indocyanine green dye mixed in deionized water, and activated with an 808-nm diode laser. The synthetic adhesive was Ethicon's Dermabond, a 2-octyl-cyanoacrylate. The tensile strength of skin incisions repaired ex vivo in a rat model, by adhesive alone or in combination with a scaffold, as well as the time-to-failure, were measured and compared. The tensile strength of repairs formed using the scaffold-enhanced biological adhesives were on average, 80% stronger than their non-enhanced counterparts, with an accompanying increase in the time-to-failure of the repairs. These results support the theory that a scaffold material with an irregular surface that bridges the wound provides a stronger, more durable and consistent adhesion, due to the distribution of the tensile stress forces over the many micro-adhesions provided by the irregular surface, rather than the one large continuous adhesive contact. This theory is also supported by several previous ex vivo experiments demonstrating enhanced tensile strength of irregular versus smooth scaffold surfaces in identical tissue repairs performed on bovine thoracic aorta, liver, spleen, small intestine and lung tissue.

  16. Quadruple Lap Shear Processing Evaluation

    NASA Technical Reports Server (NTRS)

    Thornton, Tony N.; McCool, A. (Technical Monitor)

    2000-01-01

    The Thiokol, Science and Engineering Huntsville Operations (SEHO) Laboratory has previously experienced significant levels of variation in testing Quadruple Lap Shear (QLS) specimens. The QLS test is used at Thiokol / Utah for the qualification of Reusable Solid Rocket Motor (RSRM) nozzle flex bearing materials. A test was conducted to verify that process changes instituted by SEHO personnel effectively reduced variability, even with normal processing variables introduced. A test matrix was designed to progress in a series of steps; the first establishing a baseline, then introducing additional solvents or other variables. Variables included normal test plan delay times, pre-bond solvent hand-wipes and contaminants. Each condition tested utilized standard QLS hardware bonded with natural rubber, two separate technicians and three replicates. This paper will report the results and conclusions of this investigation.

  17. Evaluation of a thermoplastic polyimide (422) for bonding GR/PI composite

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.

    1988-01-01

    A hot-melt processable copolyimide previously studied and characterized as an adhesive for bonding Ti-6Al-4V was used to bond Celion 6000/LARC-160 composite. Comparisons are made for the two adherend systems. A bonding cycle was determined for the composite bonding and lap shear specimens were prepared which were thermally exposed in a forced-air oven for up to 5000 h at 204 C. The lap shear strengths (LSSs) were determined at RT, 177, and 204 C. After thermal exposure at RT, 177, and 204 C the LSS decreased significantly; however, a slight increase was noted for the 204 C tests. Initially the LSS values are higher for the bonded Ti-6Al-4V than for the bonded composite, however, the LSS decreases dramatically between 5000 and 10,000 h of 204 C thermal exposure. Longer periods of thermal exposure up to 20,000 h results in further decreases in the LSSs. Although the bonded composite retained useful strengths for exposures up to 5000 h, based on the poor results of the bonded Ti-6Al-4V beyond 5000 h, the 422 adhesive bonded composites would most likely also produce poor strengths beyond 5000 h exposure. Adhesive bonded composite lap shear specimens exposed to boiling water for 72 h exhibited greatly reduced strengths at all test temperatures. The percent retained after water boil for each test temperature was essentially the same for both systems.

  18. Evaluation of a thermoplastic polyimide (422) for bonding GR/PI composite

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.

    1988-01-01

    A hot-melt processable copolyimide previously studied and characterized as an adhesive for bonding Ti-6Al-4V was used to bond Celion 6000/LARC-160 composite. Comparisons are made for the two adherend systems. A bonding cycle was determined for the composite bonding and lap shear specimens were prepared which were thermally exposed in a forced-air oven for up to 5000 h at 204 C. The lap shear strengths (LSSs) were determined at RT, 177, and 204 C. After thermal exposure at RT, 177, and 204 C the LSS decreased significantly; however, a slight increase was noted for the 204 C tests. Initially the LSS values are higher for the bonded Ti-6Al-4V than for the bonded composite, however, the LSS decreases dramatically between 5000 and 10,000 h of 204 C thermal exposure. Longer periods of thermal exposure up to 20,000 h results in further decreases in the LSSs. Although the bonded composite retained useful strengths for exposures up to 5000 h, based on the por results of the bonded Ti-6Al-4V beyond 5000 h, the 422 adhesive bonded composites would most likely also produce poor strengths beyond 5000 h exposure. Adhesive bonded composite lap shear specimens exposed to boiling water for 72 h exhibited greatly reduced strengths at all test temperatures. The percent retained after water boil for each test temperature was essentially the same for both systems.

  19. Evaluation of a thermoplastic polyimide (422) for bonding GR/PI composite

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.

    1988-01-01

    A hot-melt processable copolyimide previously studied and characterized as an adhesive for bonding Ti-6Al-4V was used to bond Celion 6000/LARC-160 composite. Comparisons are made for the two adherend systems. A bonding cycle was determined for the composite bonding and lap shear specimens were prepared which were thermally exposed in a forced-air oven for up to 5000 h at 204 C. The lap shear strengths (LSSs) were determined at RT, 177, and 204 C. After thermal exposure at RT, 177, and 204 C the LSS decreased significantly; however, a slight increase was noted for the 204 C tests. Initially the LSS values are higher for the bonded Ti-6Al-4V than for the bonded composite, however, the LSS decreases dramatically between 5000 and 10,000 h of 204 C thermal exposure. Longer periods of thermal exposure up to 20,000 h results in further decreases in the LSSs. Although the bonded composite retained useful strengths for exposures up to 5000 h, based on the por results of the bonded Ti-6Al-4V beyond 5000 h, the 422 adhesive bonded composites would most likely also produce poor strengths beyond 5000 h exposure. Adhesive bonded composite lap shear specimens exposed to boiling water for 72 h exhibited greatly reduced strengths at all test temperatures. The percent retained after water boil for each test temperature was essentially the same for both systems.

  20. A new fluorinated urethane dimethacrylate with carboxylic groups for use in dental adhesive compositions.

    PubMed

    Buruiana, Tinca; Melinte, Violeta; Aldea, Horia; Pelin, Irina M; Buruiana, Emil C

    2016-05-01

    A urethane macromer containing hexafluoroisopropylidene, poly(ethylene oxide) and carboxylic moieties (UF-DMA) was synthesized and used in proportions varying between 15 and 35 wt.% (F1-F3) in dental adhesive formulations besides BisGMA, triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate. The FTIR and (1)H ((13)C) NMR spectra confirmed the chemical structure of the UF-DMA. The experimental adhesives were characterized with regard to the degree of conversion, water sorption/solubility, contact angle, diffusion coefficient, Vickers hardness, and morphology of the crosslinked networks and compared with the specimens containing 10 wt.% hydroxyapatite (HAP) or calcium phosphate (CaP). The conversion degree (after 180 s of irradiation with visible light) ranged from 59.5% (F1) to 74.8% (F3), whereas the water sorption was between 23.15 μg mm(-3) (F1) and 40.52 μg mm(-3) (F3). Upon the addition of HAP or CaP this parameter attained values of 37.82-49.14 μg mm(-3) (F1-F3-HAP) and 34.58-45.56 μg mm(-3), respectively. Also, the formation of resin tags through the infiltration of a dental composition (F3) was visualized by SEM analysis. The results suggest that UF-DMA taken as co-monomer in dental adhesives of acrylic type may provide improved properties in the moist environment of the mouth. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Rapid adhesive bonding concepts for specimen and panel fabrication and field repair

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Hodges, W. T.

    1984-01-01

    The NASA Langley Research Center has developed bonding concepts for aerospace composite materials which employ induction heating to directly apply heat to the bond line and/or adherends without simultaneously heating the entire structure, supports, and fixtures of a bonding assembly. These methods have demonstrated bonding process time reductions of two to three orders of magnitude, by comparison with conventional press molding. Attention is presently given to rapid adhesive bonding for lap shear specimens for aerospace panel bonding or field repair, as well as for the field repair requirements of metallic and advanced polymeric matrix composite structures.

  2. Single-Phase Photo-Cross-Linkable Bioinspired Adhesive for Precise Control of Adhesion Strength.

    PubMed

    Harper, Tristan; Slegeris, Rimantas; Pramudya, Irawan; Chung, Hoyong

    2017-01-18

    A bioinspired, modular terpolymer adhesive, poly(N-methacryloyl-3,4-dihydroxyl-l-phenylalanine-co-9-(acryloyloxy)butyl anthracene-9-carboxylate-co-acrylic acid), has been synthesized containing three different functionalities: a photo-cross-linking segment, a wet interfacial adhesion segment, and a water-soluble segment. The synthesized adhesive polymer is the first example of a single-phase, photo-cross-linkable adhesive which does not require additional photoinitiator or other cross-linking agents. The terpolymer demonstrates strong adhesion when it swells in water and/or ethanol. The terpolymer is composed of three repeating units: N-methacryloyl-3,4-dihydroxyl-l-phenylalanine (MDOPA), which has been known to generate strong adhesion under wet conditions, poly(acrylic acid), which has been known to increase water solubility of polymers, and a photo-cross-linking segment consisting of an anthracene-based monomer used for enhancement of cohesion properties via UV irradiation (352 nm). A photomediated [4 + 4] cycloaddition reaction of anthracene results in the cross-linking of individual polymer chains after interfacial adhesion between substrates and adhesive polymers. Chemically, the covalent photo-cross-linking was confirmed by UV-vis, (1)H NMR, and gel permeation chromatography (GPC). The cross-linking-fortified cohesion of the adhesive polymer network yields strengthened cohesion properties of the bulk material. The photoreaction was conveniently controlled via the duration of UV-irradiation. The adhesion properties of new adhesives were characterized by lap shear strength on transparent Mylar film and glasses after the adhesive was swollen in biologically friendly solvents including water and ethanol. The adhesion strength (J/m(2)) was enhanced by 850% under 352 nm UV-irradiation. Multiple application variables were tested to determine the optimal conditions, such as solvent, concentration, polymer composition, and substrate. The best adhesion properties were

  3. Use of plasma polymerization to improve adhesion strength in carbon fiber composites cured by electron beam.

    PubMed

    Vautard, Frédéric; Fioux, Philippe; Vidal, Loïc; Siffer, Frédéric; Roucoules, Vincent; Schultz, Jacques; Nardin, Michel; Defoort, Brigitte

    2014-02-12

    Maleic anhydride plasma polymer was deposited at the surface of carbon fibers and functionalized with vinyl and thiol groups to improve its adhesion strength with an acrylate matrix cured by an electron beam. A characterization of the fiber surface properties was done before and after coating (topography, surface chemistry, and surface energy). Sharp improvements of the interfacial shear strength (+ 120%), measured by a micromechanical test derived from the pull-out test, were obtained and, to the best of our knowledge, never reported before. The values were close to the ones obtained with a thermal cure. The comparison of this approach with other types of surface treatments (oxidation, grafting of coupling agents) enabled the establishment of a general strategy for the improvement of the interfacial adhesion in carbon fiber composites cured by an electron beam and potentially the improvement of their mechanical properties. This strategy is based on a high surface density of functionalities that are generating covalent bonding during the polymerization of the matrix and on the insertion of a polymer layer strongly attached to the fiber surface and acting as a buffer between the fiber surface and the matrix to counteract the generation of stress in the interphase.

  4. Shear Bond Strengths of Methacrylate- and Silorane-based Composite Resins to Feldspathic Porcelain using Different Adhesive Systems

    PubMed Central

    Mohammadi, Narmin; Shakur Shahabi, Maryam; Kimyai, Soodabeh; Pournagi Azar, Fatemeh; Ebrahimi Chaharom, Mohammad Esmaeel

    2015-01-01

    Background and aims. Use of porcelain as inlays, laminates and metal-ceramic and all-ceramic crowns is common in modern dentistry. The high cost of ceramic restorations, time limitations and difficulty of removing these restorations result in delays in replacing fractured restorations; therefore, their repair is indicated. The aim of the present study was to compare the shear bond strengths of two types of composite resins (methacrylate-based and silorane-based) to porcelain, using three adhesive types. Materials and methods. A total of 156 samples of feldspathic porcelain surfaces were prepared with air-abrasion and randomly divided into 6 groups (n=26). In groups 1-3, Z250 composite resin was used to repair porcelain samples with Ad-per Single Bond 2 (ASB), Clearfil SE Bond (CSB) and Silorane Adhesive (SA) as the bonding systems, afterapplication of silane, respectively. In groups 4-6, the same adhesives were used in the same manner with Filtek Silorane composite resin. Finally, the shear bond strengths of the samples were measured. Two-way ANOVA and post hoc Tukey tests were used to compare bond strengths between the groups with different adhesives at P<0.05. Results. There were significant differences in the mean bond strength values in terms of the adhesive type (P<0.001). In addition, the interactive effect of the adhesive type and composite resin type had no significant effect on bond strength (P=0.602). Conclusion. The results of the present study showed the highest repair bond strength values to porcelain with both composite resin types with the application of SA and ASB. PMID:26697151

  5. Effect of the applied power of atmospheric pressure plasma on the adhesion of composite resin to dental ceramic.

    PubMed

    Han, Geum-Jun; Chung, Sung-No; Chun, Bae-Hyeock; Kim, Chang-Keun; Oh, Kyu-Hwan; Cho, Byeong-Hoon

    2012-08-01

    To evaluate the effect of applied power on dental ceramic bonding of composite resin using nonthermal atmospheric pressure plasma (APP). A pencil-type APP torch was used to modify the surface chemical composition and hydrophilicity of dental ceramic and to improve the adhesion of composite resin to the surface. The effect of the applied power on chemical changes of the plasma polymer on a ceramic surface and the adhesive strength between the composite resin and feldspathic porcelain were examined. Adhesion was evaluated by comparing shear bond strengths (SBS) using the iris method. The chemical composition of the plasma polymer deposited on the ceramic surface was evaluated using x-ray photoelectron spectroscopy (XPS). Hydrophilicity was evaluated by contact angle measurements. The fracture mode at the interface was also evaluated. The APP treatment was effective and the SBS of the experimental groups were significantly higher than those of the negative control group (p < 0.05). Moreover, the SBS obtained with the APP treatment at the highest input voltage was statistically similar to the gold standard of HF etching and silane coupling-agent coating. Two-thirds of the fractures observed in the specimens bonded with application of APP were mixed and cohesive fractures. Application of APP enhanced adhesion by producing carboxyl groups on the ceramic surface and as a result by improving surface hydrophilicity. The carboxyl group contents in the plasma polymer on the ceramic surface increased as the applied power increased.

  6. Quantitative comparison of the water permeable zone among four types of dental adhesives used with a dual-cured composite.

    PubMed

    Chang, Juhea; Platt, Jeffrey A; Yi, Keewook; Cochran, Michael A

    2006-01-01

    This study compared silver penetration in the adhesive interface among four versions of adhesives from the same manufacturer: OptiBond FL, OptiBond Solo Plus, OptiBond Solo Plus Dual Cure, and OptiBond Solo Plus Self-Etch, when coupled with dual-cured composite, CoreRestore 2 (Kerr). Twenty flat dentin surfaces were prepared using one of the adhesives and bonded with the composite, following the manufacturer's instructions. The surfaces were sectioned into 2-mm slabs and immersed in ammoniacal silver nitrate for 24 hours. Each specimen was exposed to a photodeveloping solution for eight hours and examined with a scanning electron microscope (SEM). The water permeable area occupied by the silver nitrate tracer was determined, and the relative weight of silver was analyzed by wavelength dispersive spectrometry (WDS). The OptiBond FL group had a significantly lower silver content than the other groups (p < 0.0001). Each group demonstrated different patterns of silver deposition within the adhesive layer and within various features of artifactual fracture from dehydration stress of the SEM. This may be indicative of weak links in the bonded interfaces. Simplified-step adhesives showed increased permeability, which can lead to disruption of coupling with composites.

  7. Supersonic Retropulsion Surface Preparation of Carbon Fiber Reinforced Epoxy Composites for Adhesive Bonding

    NASA Technical Reports Server (NTRS)

    Palmieri, Frank L.; Belcher, Marcus A.; Wohl, Christopher J.; Blohowiak, Kay Y.; Connell, John W.

    2013-01-01

    Surface preparation is widely recognized as a key step to producing robust and predictable bonds in a precise and reproducible manner. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, can lack precision and reproducibility, which can lead to variation in surface properties and subsequent bonding performance. The use of a laser to ablate composite surface resin can provide an efficient, precise, and reproducible means of preparing composite surfaces for adhesive bonding. Advantages include elimination of physical waste (i.e., grit media and sacrificial peel ply layers that ultimately require disposal), reduction in process variability due to increased precision (e.g. increased reproducibility), and automation of surface preparation, all of which improve reliability and process control. This paper describes a Nd:YAG laser surface preparation technique for composite substrates and the mechanical performance and failure modes of bonded laminates thus prepared. Additionally, bonded specimens were aged in a hot, wet environment for approximately one year and subsequently mechanically tested. The results of a one year hygrothermal aging study will be presented.

  8. Effect of time on the flexural strength of glass ionomer and composite orthodontic adhesives.

    PubMed

    Azevedo, Christophe; Forestier, Jean-Paul; Tavernier, Bruno

    2005-01-01

    The purpose of this study was to compare the effects of time on the flexural strength of a resin-reinforced glass ionomer and a composite adhesive system, specifically at three time frames corresponding to the three stages of polymerization of Fuji Ortho LC. Ten rectangular specimens of each material were prepared in a metal mold (25 x 2 x 2 mm) and then stored at 37 degrees C and 100% humidity in an incubator. Six test groups were created, in which each specimen was fractured using a 3-point-bending test at a crosshead speed of 0.5 mm/min. The test results indicated that there were significant differences among the groups (P = .0001). The flexural strengths were significantly higher in the two groups (III and VI) that were fractured after seven days. This was true for both the Fuji Ortho LC (x = 77 +/- 6.1 MPa) and the Concise (x = 103.9 +/- 4.2 MPa). The flexural strength of the resin-modified glass ionomer adhesive was significantly lower than that for the composite whatever the time of fracture, 10 minutes, one hour, or seven days. The analysis of the strength-deformation curve of the group of Fuji Ortho LC, which was fractured within 10 minutes after setting (group I), showed viscoplastic behavior, whereas that of all the others groups showed elastic behavior. According to this study, clinicians must consider the mechanics of Fuji Ortho LC setting and, when this material is used, wait for at least one hour to ligate initial or repaired arch wires.

  9. Elastomer-toughened polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Saint Clair, A. K.; Saint Clair, T. L.

    1980-01-01

    A study has been conducted to determine the effects of added elastomers on the Tg, thermal stability, adhesive strength, and fracture toughness of LARC-13, a high-temperature addition polyimide adhesive. Various butadiene/acrylonitrile and silicone elastomers were incorporated into the polyimide resin (1) as physical polyblends, and (2) by chemically reacting the elastomers with the polyimide backbone. Adhesive single lap-shear and T-peel strengths were measured before and after aging at elevated temperature. A tapered double-cantilever beam specimen was used to determine the fracture toughness of the elastomer-modified polyimide adhesives.

  10. The Effect of Surface Irregularities on Wing Drag. II - Lap Joints. 2; Lap Joints

    NASA Technical Reports Server (NTRS)

    Hood, Manley J.

    1938-01-01

    Tests have been made in the NACA 8-foot high-speed wind tunnel of the drag caused by four types of lap joint. The tests were made on an airfoil of NACA 23012 section and 5-foot chord and covered in a range of speeds from 80 to 500 miles per hour and lift coefficients from 0 to 0.30. The increases in profile drag caused by representative arrangements of laps varied from 4 to 9%. When there were protruding rivet heads on the surface, the addition of laps increased the drag only slightly. Laps on the forward part of a wing increased the drag considerably more than those farther back.

  11. Active Metal Brazing and Adhesive Bonding of Titanium to C/C Composites for Heat Rejection System

    NASA Technical Reports Server (NTRS)

    Singh, M.; Shpargel, Tarah; Cerny, Jennifer

    2006-01-01

    Robust assembly and integration technologies are critically needed for the manufacturing of heat rejection system (HRS) components for current and future space exploration missions. Active metal brazing and adhesive bonding technologies are being assessed for the bonding of titanium to high conductivity Carbon-Carbon composite sub components in various shapes and sizes. Currently a number of different silver and copper based active metal brazes and adhesive compositions are being evaluated. The joint microstructures were examined using optical microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). Several mechanical tests have been employed to ascertain the effectiveness of different brazing and adhesive approaches in tension and in shear that are both simple and representative of the actual system and relatively straightforward in analysis. The results of these mechanical tests along with the fractographic analysis will be discussed. In addition, advantages, technical issues and concerns in using different bonding approaches will also be presented.

  12. Conditioning of root canals prior to dowel cementation with composite luting cement and two dentine adhesive systems.

    PubMed

    Liberman, R; Ben-Amar, A; Urstein, M; Gontar, G; Fitzig, S

    1989-11-01

    Two hundred and forty root canals of extracted single-rooted teeth were prepared to the same dimension, and Dentatus posts of equal size were cemented without screwing them into the dentine. Five cleansing solutions and two dentine adhesive systems were evaluated prior to post-cementation using chemical-cure composite resin. 'Pull-out' tests were then conducted in order to evaluate the bond strength of these intra-pulpal posts. The use of Conclude (composite luting cement) alone, with or without the cleansing solutions, resulted in significantly lower pull-out forces. Scotchbond Dental Adhesive gave significantly better results, regardless of the cleansing solution used. Gluma Dentine Adhesive significantly increased the pull-out forces only when used with its supplied cleanser or Tubulicid.

  13. Comparison of Shear Bond Strength and Estimation of Adhesive Remnant Index between Light-cure Composite and Dual-cure Composite: An in vitro Study

    PubMed Central

    Trehan, Mridula; Sharma, Sunil

    2013-01-01

    ABSTRACT Aims and objectives: To measure and compare the shear bond strength and adhesive remnant index of light-cure composite. (Enlight, Ormco.) and dual-cure composite (Phase II dual cure, Reliance Ortho). Materials and methods: Sixty extracted human premolar teeth were divided into two groups: group I (blue): conventional light cure composite resin. (Enlight, Ormco.) and group II (green): dual cure composite resin. (Phase II dual cure, Reliance Ortho.) with 30 teeth in each group. These samples were tested on the universal testing machine to measure the shear bond strength. Results: Student t-test showed that the mean shear bond strength of the conventional light cure group (8.54 MPa - 10.42 MPa) was significantly lower than dual cure group (10.45 MPa -12.17 MPa). Conclusion: These findings indicate that the shear bond strength of dual-cure composite resin (Phase II dual cure, Reliance Ortho) is comparatively higher than conventional light-cure composite resin (Enlight, Ormco). In the majority of the samples, adhesive remnant index (ARI) scores were 4 and 5 in both the groups whereas score 1 is attained by the least number of samples in both the groups. How to cite this article: Verma G, Trehan M, Sharma S. Comparison of Shear Bond Strength and Estimation of Adhesive Remnant Index between Light-cure Composite and Dual-cure Composite: An in vitro Study. Int J Clin Pediatr Dent 2013;6(3):166-170. PMID:25206216

  14. Effect of Atmospheric Pressure Plasma Treatment on Surface Characteristics and Adhesive Bond Quality of Peel Ply Prepared Composites

    NASA Astrophysics Data System (ADS)

    Tracey, Ashley C.

    The purpose of this research was to investigate if atmospheric pressure plasma treatment could modify peel ply prepared composite surfaces to create strong adhesive bonds. Two peel ply surface preparation composite systems previously shown to create weak bonds (low fracture energy and adhesion failure) that were potential candidates for plasma treatment were Toray T800/3900-2 carbon fiber reinforced polymer (CFRP) prepared with Precision Fabrics Group, Inc. (PFG) 52006 nylon peel ply and Hexcel T300/F155 CFRP prepared with PFG 60001 polyester peel ply. It was hypothesized that atmospheric pressure plasma treatment could functionalize and/or remove peel ply remnants left on the CFRP surfaces upon peel ply removal. Surface characterization measurements and double cantilever beam (DCB) testing were used to determine the effects of atmospheric pressure plasma treatment on surface characteristics and bond quality of peel ply prepared CFRP composites. Previous research showed that Toray T800/3900-2 carbon fiber reinforced epoxy composites prepared with PFG 52006 peel ply and bonded with Cytec MetlBond 1515-3M structural film adhesive failed in adhesion at low fracture energies when tested in the DCB configuration. Previous research also showed that DCB samples made of Hexcel T300/F155 carbon fiber reinforced epoxy composites prepared with PFG 60001 peel ply and bonded with Henkel Hysol EA 9696 structural film adhesive failed in adhesion at low fracture energies. Recent research suggested that plasma treatment could be able to activate these "un-bondable" surfaces and result in good adhesive bonds. Nylon peel ply prepared 177 °C cure and polyester peel ply prepared 127 °C cure CFRP laminates were treated with atmospheric pressure plasma after peel ply removal prior to bonding. Atmospheric pressure plasma treatment was capable of significantly increasing fracture energies and changing failure modes. For Toray T800/3900-2 laminates prepared with PFG 52006 and bonded with

  15. Effect of lining with a flowable composite on internal adaptation of direct composite restorations using all-in-one adhesive systems.

    PubMed

    Yahagi, Chika; Takagaki, Tomohiro; Sadr, Alireza; Ikeda, Masaomi; Nikaido, Toru; Tagami, Junji

    2012-01-01

    The purpose of this study was to evaluate the effect of lining with a flowable composite on internal adaptation of composite restorations using three all-in-one adhesive systems; Bond Force (BF), G-Bond Plus (GP), and OptiBond All-in-one (OP), and a two-step self-etching adhesive system; Clearfil SE Bond (SE). They were applied to each cylindrical cavity prepared on the human dentin. The cavity surface was lined with/without a flowable resin composite prior to filling with a resin composite (FL/NL). After water storage for 24 h, the specimens were sectioned and polished, and internal adaptation of the restorations was assessed using a confocal laser scanning microscopy. For SE, a perfect cavity adaptation was recognized in both FL and NL. For BF, GP and OP, cavity adaptation was material dependent in NL, whereas no gap formation was observed in FL. However, voids formation was observed at the composite-adhesive-dentin interface in every all-in-one adhesive system.

  16. Plant-derived micronutrients suppress monocyte adhesion to cultured human aortic endothelial cell layer by modulating its extracellular matrix composition.

    PubMed

    Ivanov, Vadim; Ivanova, Svetlana; Kalinovsky, Tatiana; Niedzwiecki, Aleksandra; Rath, Matthias

    2008-07-01

    Monocyte adhesion to endothelium plays an important role in atherosclerosis. We investigated the effects of micronutrients on monocyte-binding properties of extracellular matrix (ECM) produced by human aortic endothelial cells (AoEC). Confluent cultures of AoEC were exposed to ascorbic acid, quercetin, gotu kola extract (10% asiatic acid), green tea extract (40% epigallocatechin gallate), or a mixture of these micronutrients for 48 hours. AoEC-produced ECM was exposed by differential treatment. U937 monocyte adhesion was assayed by fluorescence. ECM composition was assayed immunochemically and with radiolabeled metabolic precursors. AoEC exposure to micronutrients reduced ECM capacity to bind monocytes in a dose-dependent manner. This effect was accompanied by profound changes in the ECM composition. Correlation analysis revealed that changes in monocyte adhesion to ECM had the strongest positive correlation with ECM content for laminin (CC = 0.9681, P < 0.01), followed by fibronectin, collagens type III, I, and IV, biglycan, heparan sulfate, and elastin. The strongest negative correlation was with chondroitin sulfate (CC = -0.9623, P < 0.01), followed by perlecan and versican. Individual micronutrients had diverse effects on ECM composition and binding properties, and their mixture was the most effective treatment. In conclusion, micronutrient-dependent reduction of monocyte adhesion to endothelium is partly mediated through specific modulation of ECM composition and properties.

  17. Direct Pen Writing of Adhesive Particle-Free Ultrahigh Silver Salt-Loaded Composite Ink for Stretchable Circuits.

    PubMed

    Hu, Mingjun; Cai, Xiaobing; Guo, Qiuquan; Bian, Bin; Zhang, Tengyuan; Yang, Jun

    2016-01-26

    In this article, we describe a writable particle-free ink for fast fabrication of highly conductive stretchable circuits. The composite ink mainly consists of soluble silver salt and adhesive rubber. Low toxic ketone was employed as the main solvent. Attributed to ultrahigh solubility of silver salt in short-chain ketone and salt-assisted dissolution of rubber, the ink can be prepared into particle-free transparent solution. As-prepared ink has a good chemical stability and can be directly filled into ballpoint pens and use to write on different substrates to form well adhesive silver salt-based composite written traces as needed. As a result of high silver salt loading, the trace can be converted into highly conductive silver nanoparticle-based composites after in situ reduction. Because of the introduction of adhesive elastomeric rubber, the as-formed conductive composite written trace can not only maintain good adhesion to various substrates but also show good conductivity under various deformations. The conductivity of written traces can be enhanced by repeated writing-reduction cycles. Different patterns can be fabricated by either direct handwriting or hand-copying. As proof-of-concept demonstrations, a typical handwriting heart-like circuit was fabricated to show its capability to work under different deformations, and a pressure-sensitive switch was also manufactured to present pressure-dependent change of resistance.

  18. Lamination of Hardwood Composite Framing With an Emulsion Polymer-lsocyanate Adhesive and Radio-Frequency Curing

    Treesearch

    Charles B. Vick

    1987-01-01

    Composite framing msde from yellow-poplar and sweetgum parallel-laminated veneer and oriented flakeboard was effectively laminated with an emulsion polymer/isocyanate adhesive and radio-frequency curing at an assumed but typical range of material surface characteristics and factory assembly conditions.

  19. ADHESIVES WITH DIFFERENT PHS: EFFECT ON THE MTBS OF CHEMICALLY ACTIVATED AND LIGHT-ACTIVATED COMPOSITES TO HUMAN DENTIN

    PubMed Central

    Mallmann, André; de Melo, Renata Marques; Estrela, Verbênia; Pelogia, Fernanda; Campos, Laura; Bottino, Marco Antonio; Valandro, Luiz Felipe

    2007-01-01

    Purpose: To evaluate the bond strength between human dentin and composites, using two light-activated single-bottle total-etch adhesive systems with different pHs combined with chemically activated and light-activated-composites. The tested hypothesis was that the dentin bond strength is not influenced by an adhesive system of low pH, combined with chemically activated or light-activated composites. Material and Method: Flat dentin surfaces of twenty-eight human third molars were allocated in 4 groups (n=7), depending on the adhesive system: (One Step Plus-OS and Prime & Bond NT-PB) and composite (light-activated Filtek Z-100 [Z100] and chemically activated Bisfil 2B [B2B]). Each adhesive system was applied on acid-etched dentin and then one of the composites was added to form a 5 mm-high resin block. The specimens were stored in tap water (37°C/24 h) and sectioned into two axes, x and y. This was done with a diamond disk under coolant irrigation to obtain beams with a cross-section area of approximately 0.8 mm2. Each specimen was then attached to a custom-made device and submitted to the microtensile test (1 mm.min−1). Data were analyzed using two-way ANOVA and Tukey’s tests (p<0.05). Results: The anticipated hypothesis was not confirmed (p<0.0001). The bond strengths (MPa) were not statistically different between the two adhesive systems when light-activated composite was used (OS+Z100 = 24.7±7.1ª; PB+Z100 = 23.8±5.7ª). However, with use of the chemically activated composite (B2B), PB (7.8±3.6b MPa) showed significantly lower dentin bond strengths than OS (32.2±7.6ª). Conclusion: The low pH of the adhesive system can affect the bond of chemically activated composite to dentin. On the other hand, under the present conditions, the low pH did not seem to affect the bond of light-activated composites to dentin significantly. PMID:19089142

  20. Effect of the number of coats of simplified adhesive systems on microleakage of dentin-bordered composite restorations.

    PubMed

    Harada, Tánia Sayuri; Pazinatto, Flávia Bittencourt; Wang, Linda; Atta, Maria Teresa

    2006-11-01

    This study tested the null hypothesis that there is no difference on microleakage of dentin-bordered composite restorations using single or double coats of adhesive from one-bottle adhesive systems. The enamel surface was removed from freshly extracted bovine teeth, and standardized Class V cavities (3 x 3 x 1.5 mm) were made at the cervical areas of buccal surfaces. Teeth were restored and grouped according to type of adhesive systems [Prime Bond 2.1 (PB2.1), Prime & Bond NT (PBNT), and Single Bond (SB)] and to the number of coats (one or two) to be used. The restorations were polished and immersed in a 0.5% aqueous solution of basic fuchsin for four hours. Teeth were then sectioned and the most infiltrated section of each tooth was selected under magnification, scanned, and quantitatively analyzed using a computer program. Data were analyzed using two-way analysis of variance (ANOVA) and Student-Newman-Keuls (a=0.05). Groups without filler content (PB2.1 and SB) showed no difference in microleakage using single or double coats. However, PBNT (with nanofiller) showed statistically less microleakage when only one coat was applied. The influence of the number of coats of the adhesive systems on dentin margin microleakage was material dependent. All adhesive systems demonstrated microleakage, however, it could be minimized using two coats of non-filled or one coat of a filled adhesive system.

  1. The effect of oxalate desensitizers on the microleakage of resin composite restorations bonded by etch and rinse adhesive systems.

    PubMed

    Shafiei, Fereshteh; Motamedi, Mehran; Alavi, Ali Asghar; Namvar, Babak

    2010-01-01

    This in vitro study evaluated the effect of an oxalate desensitizer (OX) on the marginal microleakage of resin composite restorations bonded by two three-step and two two-step etch and rinse adhesives. Class V cavities were prepared on the buccal surfaces of 126 extracted premolars at the cementoenamel junction and randomly divided into nine groups of 14 each. In the control groups (1-4), four adhesives were applied, respectively, including Adper Scotchbond Multi-Purpose (SBMP), Optibond FL (OBFL), One-Step Plus (OS) and Excite (EX). In the experimental groups (5-8), the same adhesives, in combination with OX (BisBlock), were applied. And, in one group, OX was applied without any adhesive, as the negative control group (9). All the groups were restored with a resin composite. After 24 hours of storage in distilled water and thermocycling, the samples were placed in 1% methylene blue dye solution. The dye penetration was evaluated using a stereomicroscope. The data were analyzed using non-parametric tests. The OX application, in combination with OBFL and EX, resulted in significantly increasing microleakage at the gingival margins (p < 0.05), while it had no effect on OS and SBMP (p > 0.05). At the occlusal margins, no significant difference in microleakage was observed after OX application for each of four adhesives (p > 0.05).

  2. LAPS Grid generation and adaptation

    NASA Astrophysics Data System (ADS)

    Pagliantini, Cecilia; Delzanno, Gia Luca; Guo, Zehua; Srinivasan, Bhuvana; Tang, Xianzhu; Chacon, Luis

    2011-10-01

    LAPS uses a common-data framework in which a general purpose grid generation and adaptation package in toroidal and simply connected domains is implemented. The initial focus is on implementing the Winslow/Laplace-Beltrami method for generating non-overlapping block structured grids. This is to be followed by a grid adaptation scheme based on Monge-Kantorovich optimal transport method [Delzanno et al., J. Comput. Phys,227 (2008), 9841-9864], that equidistributes application-specified error. As an initial set of applications, we will lay out grids for an axisymmetric mirror, a field reversed configuration, and an entire poloidal cross section of a tokamak plasma reconstructed from a CMOD experimental shot. These grids will then be used for computing the plasma equilibrium and transport in accompanying presentations. A key issue for Monge-Kantorovich grid optimization is the choice of error or monitor function for equi-distribution. We will compare the Operator Recovery Error Source Detector (ORESD) [Lapenta, Int. J. Num. Meth. Eng,59 (2004) 2065-2087], the Tau method and a strategy based on the grid coarsening [Zhang et al., AIAA J,39 (2001) 1706-1715] to find an ``optimal'' grid. Work supported by DOE OFES.

  3. Adhesion of Type 1-Fimbriated Escherichia coli to Abiotic Surfaces Leads to Altered Composition of Outer Membrane Proteins

    PubMed Central

    Otto, Karen; Norbeck, Joakim; Larsson, Thomas; Karlsson, Karl-Anders; Hermansson, Malte

    2001-01-01

    Phenotypic differences between planktonic bacteria and those attached to abiotic surfaces exist, but the mechanisms involved in the adhesion response of bacteria are not well understood. By the use of two-dimensional (2D) polyacrylamide gel electrophoresis, we have demonstrated that attachment of Escherichia coli to abiotic surfaces leads to alteration in the composition of outer membrane proteins. A major decrease in the abundance of resolved proteins was observed during adhesion of type 1-fimbriated E. coli strains, which was at least partly caused by proteolysis. Moreover, a study of fimbriated and nonfimbriated mutants revealed that these changes were due mainly to type 1 fimbria-mediated surface contact and that only a few changes occurred in the outer membranes of nonfimbriated mutant strains. Protein synthesis and proteolytic degradation were involved to different extents in adhesion of fimbriated and nonfimbriated cells. While protein synthesis appeared to affect adhesion of only the nonfimbriated strain, proteolytic activity mostly seemed to contribute to adhesion of the fimbriated strain. Using matrix-assisted laser desorption ionization–time of flight mass spectrometry, six of the proteins resolved by 2D analysis were identified as BtuB, EF-Tu, OmpA, OmpX, Slp, and TolC. While the first two proteins were unaffected by adhesion, the levels of the last four were moderately to strongly reduced. Based on the present results, it may be suggested that physical interactions between type 1 fimbriae and the surface are part of a surface-sensing mechanism in which protein turnover may contribute to the observed change in composition of outer membrane proteins. This change alters the surface characteristics of the cell envelope and may thus influence adhesion. PMID:11274103

  4. Bond strength evaluation in adhesive joints using NDE and DIC methods

    NASA Astrophysics Data System (ADS)

    Poudel, Anish

    Adhesive bonding of graphite epoxy composite laminates to itself or traditional metal alloys in modern aerospace and aircraft structural applications offers an excellent opportunity to use the most efficient and intelligent combination of materials available thus providing an attractive package for efficient structural designs. However, one of the major issues of adhesive bonding is the occasional formation of interfacial defects such as kissing or weak bonds in the bondline interface. Also, there are shortcomings of existing non-destructive evaluation (NDE) methods to non-destructively detect/characterize these interfacial defects and reliably predicting the bond shear strength. As a result, adhesive bonding technology is still not solely implemented in primary structures of an aircraft. Therefore, there is a greater demand for a novel NDE tool that can meet the existing aerospace requirement for adhesive bondline characterization. This research implemented a novel Acoustography ultrasonic imaging and digital image correlation (DIC) technique to detect and characterize interfacial defects in the bondline and determine bond shear strength in adhesively bonded composite-metal joints. Adhesively bonded Carbon Fiber Reinforced Plastic (CFRP) laminate and 2024-T3 Aluminum single lap shear panels subjected to various implanted kissing/weak bond defects were the primary focus of this study. Kissing/weak bonds were prepared by controlled surface contamination in the composite bonding surface and also by improperly mixing the adhesive constituent. SEM analyses were also conducted to understand the surface morphology of substrates and their interaction with the contaminants. Morphological changes were observed in the microscopic scale and the chemical analysis confirmed the stability of the contaminant at or very close to the interface. In addition, it was also demonstrated that contaminants migrated during the curing of the adhesive from CFRP substrate which caused a

  5. An experimental study on infrared drying kinetics of an aqueous adhesive supported by polymer composite

    NASA Astrophysics Data System (ADS)

    Allanic, Nadine; Le Bideau, Pascal; Glouannec, Patrick; Deterre, Rémi

    2017-01-01

    The infrared drying of an aqueous polymer emulsion spread on a thin composite flat film is experimentally studied. The composite film is composed of polyamide fibers supported by a poly(vinyl fluoride) film. The aqueous polymer is an Ethylene Vinyl Acetate emulsion playing the role of adhesive. It is spread over the film with a low thickness, about one hundred micrometers. The aim of this work is to understand the effects of the presence of fibers on the drying of this thin-layer product. With this in mind, a specific laboratory set up composed of a near infrared heater is used in order to get the drying kinetics. First, incident heat fluxes received at the product surface and transmittances of materials (semi-transparent medium) are measured with an ad-hoc heat flux sensor. Then, many experiments are performed with and without fibers. For linking the final moisture content to the fibers thermal and hydric behavior, a microscopic analysis of the dried samples is investigated. This analysis is performed for two thicknesses of polymer corresponding to two covering rates of fibers.

  6. Shock adhesion test for composite bonded assembly using a high pulsed power generator

    NASA Astrophysics Data System (ADS)

    Gay, E.; Berthe, L.; Buzaud, E.; Boustie, M.; Arrigoni, M.

    2013-07-01

    In a context of the rising use of composite assemblies in aeronautic or defense fields, the assessment of their strength is a key issue. The method developed in this study attempts to provide solutions. A shock adhesion test based on short compressive loads, obtained by a high pulsed power generator, is proposed as a proof test to ensure the quality of composite bonded assemblies. A calibrated load induces a local tensile stress able to damage the bond interface. The high pulsed power source is the GEnerateur de Pression Isentropique device (Isentropic Pressure Generator), used to generate the required stresses, with a 450 ns pulse duration to test assemblies above the mm thickness range. The understanding of the mechanisms of wave propagation and tensile stress generation within these multilayer assemblies are scientific challenges. The ability of the technique to induce a tensile stress able to disbond the laminates and the assemblies is demonstrated. This paper details the response of carbon epoxy laminates and their bonded assemblies to a shock loading near the damage threshold.

  7. Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites.

    PubMed

    Bertolo, Marcus Vinicius Loureiro; Moraes, Rita de Cássia Martins; Pfeifer, Carmem; Salgado, Vinícius Esteves; Correr, Ana Rosa Costa; Schneider, Luis Felipe J

    2017-01-01

    The aim of this study was to determine the influence of photoinitiator systems on physical-chemical properties of flowable composites. Conventional (CFC), composed by bisphenol-glycidyl dimethacrylate (BisGMA)+triethyleneglycol dimethacrylate (TEGDMA), and self-adhesive (SAFC), composed by BisGMA+TEDGMA+bis{2-(methacryloyloxy) ethyl} phosphate (2MP), flowable composites were developed. Five photoinitiator systems were tested: camphorquinone (CQ), ethyl-4-dimethylaminobenzoate (EDMAB), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis (2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), CQ+EDMAB+TPO and CQ+EDMAB+BAPO. A two-peak LED was used; degree of conversion (DC) and the maximum polymerization rate (RPmax) were determined by near infrared spectroscopy. For the yellowing degree a spectrophotometer was used. Water sorption (Wsp) was obtained after 30 days of water storage (n=5). Data were submitted to two-way analysis of variance and Tukey's test (a=0.05). BAPO presented the highest DC and RPmax values for both series. SAFCs presented lower DC and RPmax for CQ+EDMAB-based materials. Greater yellowing was observed for SAFCs compared with CFCs, except for BAPO. Greater Wsp was observed for SAFCs compared with CFCs. The photoinitiator did not influence Wsp for CFCs, but TPO and BAPO presented the highest Wsp in SAFCs. The photoinitiator system affected differently the physical-chemical properties of CFCs and SAFCs.

  8. In vitro detection of DNA damage in human leukocytes induced by combined effect of resin composites and adhesive systems.

    PubMed

    Marovic, Danijela; Tadin, Antonija; Mladinic, Marin; Juric-Kacunic, Danijela; Galic, Nada

    2014-02-01

    To simultaneously evaluate the genotoxicity of dental composites and adhesive systems in vitro using a cytogenetic assay, with respect to the influence of composite shade. Genotoxicity assessment was carried out in human peripheral blood leukocytes using the comet assay. Three resin composite materials, two microhybrids and one nano-hybrid, in shade A1 and A3.5 were used with manufacturer-recommended four adhesive systems. Cultures were treated for 48 hours with samples after elusion for 1 hour, 1 day, 7 days or 30 days, in two different concentrations (4.16 mg/mL, 8.33 mg/mL). Kruskall-Wallis test was used for the statistical analysis (alpha = 0.05). For combinations of micro-hybrid composite (A3.5) with two self-etch adhesives (16.1 +/- 5.50 and 16.2 +/- 9.52) after exposure to samples eluted for 1 day, the incidence of primary DNA damage was significantly higher than for the corresponding negative control (14.7 +/- 2.85). Genotoxicity was also higher after treatment with samples eluted for 1 hour (15.3 +/- 4.70) and 1 day (15.3 +/- 9.10), comprised of nano-hybrid composite (A1) with self-etch adhesive in relation to the control (13.1 +/- 1.70). There was no clear trend of increased DNA damage in material combinations with darker shades of composites. Material composition and higher material concentrations showed greater influence on the genotoxicity.

  9. Evaluation of dental adhesive systems with amalgam and resin composite restorations: comparison of microleakage and bond strength results.

    PubMed

    Neme, A L; Evans, D B; Maxson, B B

    2000-01-01

    A variety of laboratory tests have been developed to assist in predicting the clinical performance of dental restorative materials. Additionally, more than one methodology is in use for many types of tests performed in vitro. This project assessed and compared results derived from two specific laboratory testing methods, one for bond strength and one for microleakage. Seven multi-purpose dental adhesives were tested with the two methodologies in both amalgam and resin composite restorations. Bond strength was determined with a punch-out method in sections of human molar dentin. Microleakage was analyzed with a digital imaging system (Image-Pro Plus, Version 1.3) to determine the extent of dye penetration in Class V preparations centered at the CEJ on both the buccal and lingual surfaces of human molar teeth. There were 32 treatment groups (n = 10); seven experimental (dental adhesives) and one control (copal varnish, 37% phosphoric acid) followed by restoration with either amalgam or resin composite. Specimens were thermocycled 500 times in 5 degrees and 55 degrees C water with a one-minute dwell time. Bond strength and microleakage values were determined for each group. ANOVA and Student-Newman-Keuls tests demonstrated an interaction between restorative material and adhesive system with a significant difference among adhesives (p < 0.05). Using a multi-purpose adhesive system resulted in both a statistically significant increase in bond strength and a statistically significant decrease in extent of microleakage (p < 0.05). The effect of the adhesive upon both microleakage and bond strength was greater in the resin composite restorations than in the amalgam restorations. Bond strength testing was more discriminating than microleakage evaluation in identifying differences among materials.

  10. Delamination Damage Analyses of FRP Composite Spar Wingskin Joints with Modified Elliptical Adhesive Load Coupler Profile

    NASA Astrophysics Data System (ADS)

    Panigrahi, S. K.; Pradhan, B.

    2008-11-01

    Three-dimensional non-linear finite element analyses (FEA) for delamination damage onset and its growth in Graphite Fiber Reinforced Plastic (GFRP) composite Spar Wingskin Joints (SWJ) with modified elliptical adhesive load coupler profile for varied ratios of base width to height of the spar have been presented in this paper. Both in-plane and out-of-plane normal and shear stress variations on the interfacial surface of the wingskin between the spar and the wingskin have been evaluated. Coupled stress failure criterion has been used to predict the locations of initiation of failures due to delamination induced damages. Based on the stress and delamination damage analyses, suitable geometry of the modified elliptical adhesive load coupler profile of the SWJ has been recommended. The delamination damage has been observed to be initiated from the toe-end of the interfacial surface of the spar and the wingskin of the SWJ. Subsequently, the delamination propagations have also been studied by calculating the individual and the total Mode of Strain Energy Release Rate (SERR) along the delamination front using Modified Crack Closure Integral (MCCI) technique based on Linear Elastic Fracture Mechanics (LEFM) approach. It is seen that SERR variations along the delamination front i.e. across the width of the SWJ are not uniform. Therefore, a straight delamination front may grow into a curved delamination front as the delamination propagates. Also, it is found that Mode I SERR ( G I) governs the delamination propagation predominantly for the SWJ. Accordingly, suitable delamination arresting mechanism has been suggested.

  11. The effect of different adhesive types and curing methods on microleakage and the marginal adaptation of composite veneers.

    PubMed

    Maleknejad, Fathemeh; Moosavi, Horieh; Shahriari, Resa; Sarabi, Nasrin; Shayankhah, Taybeh

    2009-05-01

    The aim of this in vitro study was to evaluate the influence of application techniques (with pre-curing vs without pre-curing) for dentin adhesive on microleakage and marginal adaptation of indirect composite veneer restorations. A total-etch bonding system, Excite/Variolink II (EXV), and a self-etching primer system, Panavia F2.0 (PF2), were used in the study. Forty-eight human central incisors were prepared for composite veneer restorations. The teeth were divided into two groups (n=24). For each resin cement, one half of each experimental group included an adhesive pre-cure (PC) with a halogen light source while the other half received no pre-cure (NPC) prior to resin cement insertion. Thus, four experimental groups were created: A (PC+EXV), B (NPC+EXV), C (PC+PF2), and D (NPC+PF2). Veneers made of Tetric Ceram resin composite were cemented using dual-cured resin luting agents. After storage in distilled water at 37 degrees C for 24 hours, the teeth were prepared for marginal leakage. Two samples of each group were selected at random for scanning electron microscopic (SEM) observation and evaluation of marginal adaptation at 1050x magnification. Data were analyzed using the Kruskal-Wallis and Mann-Whitney tests (a <0.05). The highest and lowest microleakage values were observed in dentinal margins of groups B and A, respectively. Dentin margins opposite to enamel margins had a significant difference in microleakage values of PC and NPC groups (P<0.05). The influence of the adhesive pre-cure was more pronounced than the type of resin cement used. No adhesive layer was visualized for the adhesives used without employing the pre-curing step. The effect of pre-cured adhesives was not material specific. The pre-cured adhesives showed the best resistance to dye penetration although the film thickness of these luting agents was only slightly increased. Different curing methods (with pre-curing/without pre-curing) regardless of total-etch or self-etch adhesive systems

  12. Shear bond strength of a novel light cured calcium silicate based-cement to resin composite using different adhesive systems.

    PubMed

    Alzraikat, Hanan; Taha, Nessrin A; Qasrawi, Deema; Burrow, Michael F

    2016-12-01

    The shear bond strength (SBS) of TheraCal LC to resin composite was evaluated in comparison to Mineral trioxide aggregate (ProRoot MTA) and conventional glass ionomer cement (GIC) using two adhesive systems. A hole was prepared in 90 acrylic blocks (6 mm diameter, 2 mm deep) then filled with TheraCal LC, MTA or Fuji IX (n=30/group). Each group was bonded with either an etch and rinse or 1-step self-etch adhesive. Filtek Z250 composite was bonded to each capping material. Bond strength was tested in a universal testing machine, and data were analyzed using 2-way ANOVA and Duncan's Multiple range test (p<0.05). TheraCal LC displayed the highest SBS (p<0.001). MTA bonded with the 1-step self-etch adhesive showed the lowest SBS (p<0.001), while SBS of TheraCal LC and Fuji IX did not differ between either adhesive (p>0.05). TheraCal LC is the preferred choice in pulp capping procedures when using resin composite restorations.

  13. Effect of food and oral simulating fluids on structure of adhesive composite systems.

    PubMed

    Lee, S Y; Greener, E H; Mueller, H J

    1995-02-01

    This work evaluates the degradation of three adhesive/composite systems (Tenure/Marathon One. Scotchbond Multi-Purpose/Z100 and Optibond/Herculite XRV) upon immersion in 75% ethanol solution and in an artificial saliva (Moi-Stir). Shear bond strength (SBS) and diametral tensile strength (DTS) specimens were employed for this study. For the SBS specimens, the bonded interface and composite were exposed to food and oral simulating fluids at 37 degrees C for up to 30 days. A similar control series was stored in air. DTS specimens were stored in 75% ethanol at 37 degrees C for up to 30 days. The SBS specimens were sheared to failure. Small quantities of bonding resin were removed from the tooth side of the fractured surface and from the non-fractured fractured end of the composite for Fourier transform infrared microscopic evaluation. Similar scrapings were taken from DTS specimen surfaces. The infrared absorbance intensity (AI) of the major peaks was measured as a function of storage time and ratioed against the aromatic C = C (1609.4 cm-1) peak. The data were analysed using ANOVA and the Tukey LSD test. The AI of major peaks was similar for the materials stored either in air or in Moi-Stir for all testing periods. Storage in ethanol caused the AI of aliphatic C = C (1638 cm-1) and of O-H (approximately 3500 cm-1) bonds to significantly decrease (30-50%) for specimens of bonding resin while the AI of C = O bonds (1730 cm-1) increased (60-120%).(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Time-temperature effect in adhesively bonded joints

    NASA Technical Reports Server (NTRS)

    Delale, F.; Erdogan, F.

    1981-01-01

    The viscoelastic analysis of an adhesively bonded lap joint was reconsidered. The adherends are approximated by essentially Reissner plates and the adhesive is linearly viscoelastic. The hereditary integrals are used to model the adhesive. A linear integral differential equations system for the shear and the tensile stress in the adhesive is applied. The equations have constant coefficients and are solved by using Laplace transforms. It is shown that if the temperature variation in time can be approximated by a piecewise constant function, then the method of Laplace transforms can be used to solve the problem. A numerical example is given for a single lap joint under various loading conditions.

  15. Effects of molecular weight and surface functionalization on surface composition and cell adhesion to Hyaluronan coated titanium.

    PubMed

    Morra, M; Cassinelli, C; Carpi, A; Giardino, R; Fini, M

    2006-09-01

    This paper describes the effect of surface functionalization on surface composition and cell adhesion to titanium samples by high and low molecular weight Hyaluronan (HA). HA was covalently linked to aminated Ti surfaces obtained by two different surface functionalization techniques, that is polyethyleneimine (PEI) adsorption and deposition from allylamine plasma. The two approaches yield very different surface densities of available amino groups, affecting this way the number and frequency of surface-HA bonds and the configurational freedom of the latter. Results of cell adhesion test are dependent on the surface functionalization approach adopted, low molecular weight HA coupled to PEI functionalized Ti does not yield the same degree of resistance to cell adhesion found on other samples. These results indicate that the details of the surface functionalization step are crucial for surface engineering of implant devices by biological molecules.

  16. Adhesive properties of bonded orthodontic retainers to enamel: stainless steel wire vs fiber-reinforced composites.

    PubMed

    Foek, Dave Lie Sam; Ozcan, Mutlu; Krebs, Eliza; Sandham, Andrew

    2009-10-01

    +/- 6.7 MPa) (p > 0.05). Failure types varied within the FRC groups, but mainly composite was found left adhered on the enamel surface at varying degrees. In the stainless steel wire groups, when the retainer was applied onto the bonding agent and then covered with flowable resin, partially attached composite on the enamel was often found after debonding. When the wires were embedded in the flowable composite, the Heliobond group (group 8) showed more adhesive failures between the enamel and the composite compared to group 5, where the bonding agent was Stick Resin. Regardless of their application mode, stainless steel orthodontic bonded retainers delivered higher bond strengths than those of fiber retainers. The differences were statistically significant compared to those of Angelus Fibrex Ribbon and DentaPreg Splint.

  17. Application of Spline Variational Analysis Method in the Modeling of Composite Repairs

    DTIC Science & Technology

    2006-03-01

    mechanically fastened external metal or composite patch. In this technique, damaged material is removed by cutting a hole, filler and adhesive materials...However, because the stepped- lap configuration is readily produced by the laminating process, it is particularly well- suited to join laminated...panels ( CFRP ) with circular scarf repair patches for three repair systems: two wet lay-ups and one prepreg system. The wet lay-up was made using a

  18. Influence of methyl mercaptan on the repair bond strength of composites fabricated using self-etch adhesives.

    PubMed

    Yokokawa, Miho; Rikuta, Akitomo; Tsujimoto, Akimasa; Tsuchiya, Kenji; Shibasaki, Syo; Matsuyoshi, Saki; Miyazaki, Masashi

    2015-02-01

    The influence of methyl mercaptan on the repair bond strength of composites fabricated using self-etch adhesives was investigated. The surface free-energies were determined by measuring the contact angles of test liquids placed on composites that had been immersed in different concentrations of methyl mercaptan (0.01, 0.1, and 1.0 M). To determine the repair bond strength, self-etch adhesives were applied to the aged composite, and then newly added composites were condensed. Ten samples of each specimen were subjected to shear testing at a crosshead speed of 1.0 mm min(-1). Samples were analyzed using two-way ANOVA followed by Tukey's honestly significant difference (HSD) test. Although the dispersion force of the composites remained relatively constant, their polar force increased slightly as the concentration of methyl mercaptan increased. The hydrogen-bonding forces were significantly higher after immersion in 1.0 M methyl mercaptan, leading to higher surface-free energies. However, the repair bond strengths for the repair restorations prepared from composites immersed in 1.0 M methyl mercaptan were significantly lower than for those immersed in 0.01 and 0.10 M methyl mercaptan. Considering the results of this study, it can be concluded that the repair bond strengths of both the aged and newly added composites were affected by immersion in methyl mercaptan solutions.

  19. Effects of non-thermal atmospheric pressure pulsed plasma on the adhesion and durability of resin composite to dentin.

    PubMed

    Han, Geum-Jun; Kim, Jae-Hoon; Chung, Sung-No; Chun, Bae-Hyeock; Kim, Chang-Keun; Seo, Deog-Gyu; Son, Ho-Hyun; Cho, Byeong-Hoon

    2014-12-01

    This study investigated the effect of low-power, non-thermal atmospheric pressure plasma (NT-APP) treatments, in pulsed and conventional modes, on the adhesion of resin composite to dentin and on the durability of the bond between resin composite and dentin. A pencil-type NT-APP jet was applied in pulsed and conventional modes to acid-etched dentin. The microtensile bond strength (MTBS) of resin composite to dentin was evaluated at 24 h and after thermocycling in one control group (no plasma) and in two experimental groups (pulsed plasma and conventional plasma groups) using the Scotchbond Multi-Purpose Plus Adhesive System. Data were analyzed using two-factor repeated-measures anova and Weibull statistics. Fractured surfaces and the bonded interfaces were evaluated using a field-emission scanning electron microscope. Although there were no significant differences between the plasma treatment groups, the plasma treatment improved the MTBS compared with the control group. After thermocycling, the MTBS did not decrease in the control or conventional plasma group but increased in the pulsed plasma group. Thermocycling increased the Weibull moduli of plasma-treated groups. In conclusion, plasma treatment using NT-APP improved the adhesion of resin composite to dentin. Using a pulsed energy source, the energy delivered to the dentin was effectively reduced without any reduction in bond strength or durability.

  20. Effect of Storage Time on Bond Strength Performance of Multimode Adhesives to Indirect Resin Composite and Lithium Disilicate Glass Ceramic.

    PubMed

    Makishi, P; André, C B; Silva, Jp Lyra E; Bacelar-Sá, R; Correr-Sobrinho, L; Giannini, M

    2016-01-01

    To investigate the bond strength performance of multimode adhesives (MMAs) to indirect resin composite and lithium disilicate glass ceramic after 24 hours or one year of water storage. Thirty flat and polished plates of indirect resin composite (Epricord) and thirty lithium disilicate glass ceramic plates (IPS e.max Press) were prepared. Surfaces were pretreated using sandblasting (indirect resin composite) or hydrofluoric acid (glass-based ceramic). Specimens were bonded with one of two MMAs (Scotchbond Universal [SBU] or All-Bond Universal [ABU]) or ceramic primer and hydrophobic bonding (RelyX Ceramic Primer and Adper Scotchbond Multi-Purpose Bond) as a control (n=10). Resin cement cylinders (0.75 mm in diameter × 0.5 mm in height) were bonded to both substrate surfaces using the respective adhesives. After 24 hours or one year of water storage, bonding performance was measured by microshear bond strength (MSBS) testing. Results were analyzed using three-way ANOVA with Bonferroni post hoc tests (α=0.05). For indirect resin composite, significantly higher MSBS values were found for ABU after 24 hours (ABU > SBU = control); however, no significant difference among the adhesives was observed after one year (p>0.05). For glass-based ceramic, significantly different bond strengths were observed among the adhesives after 24 hours (control = ABU > SBU) and one year (control > SBU = ABU; p<0.05). Both MMAs tested can be considered effective alternatives for bonding to sandblasted indirect resin composite after aging, as they showed similar bond performance to that of the control group. However, separate bottles of silane bonding resin showed higher MSBS values and more durable bonding for etched glass-based ceramic.

  1. Personal electronics printing via tapping mode composite liquid metal ink delivery and adhesion mechanism.

    PubMed

    Zheng, Yi; He, Zhi-Zhu; Yang, Jun; Liu, Jing

    2014-04-04

    Printed electronics is becoming increasingly important in a variety of newly emerging areas. However, restricted to the rather limited conductive inks and available printing strategies, the current electronics manufacture is usually confined to industry level. Here, we show a highly cost-effective and entirely automatic printing way towards personal electronics making, through introducing a tapping-mode composite fluid delivery system. Fundamental mechanisms regarding the reliable printing, transfer and adhesion of the liquid metal inks on the substrate were disclosed through systematic theoretical interpretation and experimental measurements. With this liquid metal printer, a series of representative electronic patterns spanning from single wires to desired complex configurations such as integrated circuit (IC), printed-circuits-on-board (PCB), electronic paintings, or more do-it-yourself (DIY) devices, were demonstrated to be printed out with high precision in a moment. And the total machine cost already reached personally affordable price. This is hard to achieve by a conventional PCB technology which generally takes long time and is material, water and energy consuming, while the existing printed electronics is still far away from the real direct printing goal. The present work opens the way for large scale personal electronics manufacture and is expected to generate important value for the coming society.

  2. Loading Analysis of Composite Wind Turbine Blade for Fatigue Life Prediction of Adhesively Bonded Root Joint

    NASA Astrophysics Data System (ADS)

    Salimi-Majd, Davood; Azimzadeh, Vahid; Mohammadi, Bijan

    2015-06-01

    Nowadays wind energy is widely used as a non-polluting cost-effective renewable energy resource. During the lifetime of a composite wind turbine which is about 20 years, the rotor blades are subjected to different cyclic loads such as aerodynamics, centrifugal and gravitational forces. These loading conditions, cause to fatigue failure of the blade at the adhesively bonded root joint, where the highest bending moments will occur and consequently, is the most critical zone of the blade. So it is important to estimate the fatigue life of the root joint. The cohesive zone model is one of the best methods for prediction of initiation and propagation of debonding at the root joint. The advantage of this method is the possibility of modeling the debonding without any requirement to the remeshing. However in order to use this approach, it is necessary to analyze the cyclic loading condition at the root joint. For this purpose after implementing a cohesive interface element in the Ansys finite element software, one blade of a horizontal axis wind turbine with 46 m rotor diameter was modelled in full scale. Then after applying loads on the blade under different condition of the blade in a full rotation, the critical condition of the blade is obtained based on the delamination index and also the load ratio on the root joint in fatigue cycles is calculated. These data are the inputs for fatigue damage growth analysis of the root joint by using CZM approach that will be investigated in future work.

  3. Personal electronics printing via tapping mode composite liquid metal ink delivery and adhesion mechanism

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; He, Zhi-Zhu; Yang, Jun; Liu, Jing

    2014-04-01

    Printed electronics is becoming increasingly important in a variety of newly emerging areas. However, restricted to the rather limited conductive inks and available printing strategies, the current electronics manufacture is usually confined to industry level. Here, we show a highly cost-effective and entirely automatic printing way towards personal electronics making, through introducing a tapping-mode composite fluid delivery system. Fundamental mechanisms regarding the reliable printing, transfer and adhesion of the liquid metal inks on the substrate were disclosed through systematic theoretical interpretation and experimental measurements. With this liquid metal printer, a series of representative electronic patterns spanning from single wires to desired complex configurations such as integrated circuit (IC), printed-circuits-on-board (PCB), electronic paintings, or more do-it-yourself (DIY) devices, were demonstrated to be printed out with high precision in a moment. And the total machine cost already reached personally affordable price. This is hard to achieve by a conventional PCB technology which generally takes long time and is material, water and energy consuming, while the existing printed electronics is still far away from the real direct printing goal. The present work opens the way for large scale personal electronics manufacture and is expected to generate important value for the coming society.

  4. Aminophenoxycyclotriphosphazene cured epoxy resins and the composites, laminates, adhesives and structures thereof

    NASA Technical Reports Server (NTRS)

    Kumar, Devendra (Inventor); Fohlen, George M. (Inventor); Parker, John A. (Inventor)

    1977-01-01

    Aminophenoxy cyclotriphosphazenes such as hexakis (4-aminophenoxy) cyclotriphosphazene and tris (4-aminophenoxy)-tris phenoxy cyclotriphosphazene are used as curing agents for epoxy resins. These 1,2-epoxy resins are selected from di- or polyepoxide containing organic moieties of the formula (CH2-CHO-CH2) m-W-R-W- (CH2CH-CH2O)m where R is diphenyl dimethylmethane, diphenylmethane; W is a nitrogen or oxygen atom; and m is 1 when W is oxygen and 2 when W is nitrogen. The resins are cured thermally in stages at between about 110 to 135 C for between about 1 and 10 min, then at between about 175 to 185 C for between 0.5 to 10 hr and post cured at between about 215 and 235 C for between 0.1 and 2 hr. These resins are useful for making fire resistant elevated temperature stable composites, laminates, molded parts, and adhesives and structures, usually for aircraft secondary structures and for spacecraft construction.

  5. Effect of adherend thickness and mixed mode loading on debond growth in adhesively bonded composite joints

    NASA Technical Reports Server (NTRS)

    Mangalgiri, P. D.; Johnson, W. S.; Everett, R. A., Jr.

    1986-01-01

    Symmetric and unsymmetric double cantilever beam (DCB) specimens were tested and analyzed to assess the effect of: (1) adherend thickness, and (2) a predominantly mode I mixed mode loading on cyclic debond growth and static fracture toughness. The specimens were made of unidirectional composite (T300/5208) adherends bonded together with EC3445 structural adhesive. The thickness was 8, 16, or 24 plies. The experimental results indicated that the static fracture toughness increases and the cyclic debond growth rate decreases with increasing adherend thickness. This behavior was related to the length of the plastic zone ahead of the debond tip. For the symmetric DCB specimens, it was further found that displacement control tests resulted in higher debond growth rates than did load control tests. While the symmetric DCB tests always resulted in cohesive failures in the bondline, the unsymmetric DCB tests resulted in the debond growing into the thinner adherend and the damage progressing as delamination in that adherend. This behavior resulted in much lower fracture toughness and damage growth rates than found in the symmetric DCB tests.

  6. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    NASA Astrophysics Data System (ADS)

    Li, Ying; Manolache, Sorin; Qiu, Yiping; Sarmadi, Majid

    2016-02-01

    In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  7. Personal electronics printing via tapping mode composite liquid metal ink delivery and adhesion mechanism

    PubMed Central

    Zheng, Yi; He, Zhi-Zhu; Yang, Jun; Liu, Jing

    2014-01-01

    Printed electronics is becoming increasingly important in a variety of newly emerging areas. However, restricted to the rather limited conductive inks and available printing strategies, the current electronics manufacture is usually confined to industry level. Here, we show a highly cost-effective and entirely automatic printing way towards personal electronics making, through introducing a tapping-mode composite fluid delivery system. Fundamental mechanisms regarding the reliable printing, transfer and adhesion of the liquid metal inks on the substrate were disclosed through systematic theoretical interpretation and experimental measurements. With this liquid metal printer, a series of representative electronic patterns spanning from single wires to desired complex configurations such as integrated circuit (IC), printed-circuits-on-board (PCB), electronic paintings, or more do-it-yourself (DIY) devices, were demonstrated to be printed out with high precision in a moment. And the total machine cost already reached personally affordable price. This is hard to achieve by a conventional PCB technology which generally takes long time and is material, water and energy consuming, while the existing printed electronics is still far away from the real direct printing goal. The present work opens the way for large scale personal electronics manufacture and is expected to generate important value for the coming society. PMID:24699375

  8. Deproteinization technique stabilizes the adhesion of the fiberglass post relined with resin composite to root canal.

    PubMed

    Cecchin, Doglas; Almeida, José F A; Gomes, Brenda P F A; Zaia, Alexandre A; Ferraz, Caio C R

    2012-02-01

    To evaluate the effects of pretreatment of root dentin by 5.25% sodium hypochlorite (NaOCl) alone, associated with 2% chlorhexidine in gel base (CHX) and/or ethanol (EtOH), and the air-drying technique (Air) on the bond strength and adhesive durability of fiberglass post relined with resin composite to root dentin. A total of 100 bovine incisor roots were divided into 10 groups: G1 (control), irrigation with physiologic solution; G2, Air; G3, NaOCl; G4, NaOCl + Air; G5, NaOCl + EtOH; G6, NaOCl + EtOH + Air; G7, NaOCl + CHX; G8, NaOCl + CHX + Air; G9, NaOCl + CHX + EtOH; G10, NaOCl + CHX + EtOH + Air. Fiberglass post relined with resin composite was cemented and each group was randomly divided into two subgroups: 24 h of water storage and 12 months of water storage. The push-out test was performed and bond strength values were analyzed by ANOVA and Tukey's test. The use of NaOCl alone or associated with CHX had the highest values of bond strength with or without Air in the immediate and stored groups, being statistically similar to the immediate control group (p > 0.05). The groups using EtOH or Air alone had lower bond strength in the immediate and stored groups (p < 0.05). A significant decrease with the time of the bond strength in the control group was observed after 12 months of storage (p > 0.05). The use of NaOCl or NaOCl associated with CHX preserved the bond strength immediate and for 12 months. The air-drying technique and the other associations decreased the immediate bond strength values. Copyright © 2011 Wiley Periodicals, Inc.

  9. The effect of acrylate-based dental adhesive solvent content on microleakage in composite restorations

    PubMed Central

    Mirzakhani, Mahboubeh; Mousavinasab, Sayed Mostafa; Atai, Mohammad

    2016-01-01

    Background: This study aimed to evaluate the effect of different percentages of ethanol solvent of an experimental methacrylate-based dentin bonding agent containing polyhedral oligomeric silsesquioxanes (POSS) on the microleakage of resin composite restorations. Materials and Methods: In this experimental study, 42 extracted human premolar teeth used and 84 standard Class V cavities were prepared on the buccal and lingual surfaces of the teeth. The teeth were divided into 6 groups of 7. Experimental bonding agents with different percentages of solvent were used in 5 groups and Single Bond® as a control. The teeth were restored with resin composite and subjected to thermal cycling test. Teeth were then immersed in a solution of 2% basic fuchsine dye for 24 h and sectioned buccolingually and scored using stereomicroscope with ×32 magnification. Microleakage data were analyzed using the Kruskal–Wallis, Mann–Whitney U, and Wilcoxon tests. Results: There were significant differences between the microleakage enamel margins (P = 0.036) and dentinal margins (P = 0.008) in all the groups. These significant differences were seen between the control group and groups containing 46 wt% solvent (P = 0.011), 46 wt% and 31 wt% solvent in dentinal (P = 0.027), 31 wt% and 0 wt% in enamel (P = 0.021), also 0 wt% and control in enamel (P = 0.039), and dentinal margins microleakage (P = 0.004). The microleakage in dentinal margins was higher than enamel margins (P < 0.001). In the groups with 46 wt% solvent (P = 0.103), 0 wt% (P = 0.122), and control group (P = 0.096), however, this difference was not significant. Conclusion: The adhesive containing 31 wt% solvent showed the least marginal microleakage, presence of POSS filler may also result in the reduction of microleakage. PMID:28182040

  10. An orientation-selective orthogonal lapped transform.

    PubMed

    Kunz, Dietmar

    2008-08-01

    A novel critically sampled orientation-selective orthogonal lapped transform called the lapped Hartley transform (LHT) is derived. In a first step, overlapping basis functions are generated by modulating basis functions of a 2-D block Hartley transform by a cosine wave. To achieve invertibility and orthogonality, an iterative filter is applied as prefilter in the analysis and as postfilter in the synthesis operation, respectively. Alternatively, filtering can be restricted to analysis or synthesis, ending up with a biorthogonal transform (LHT-PR, LHT-PO). A statistical analysis based on a 4000-image data base shows that the LHT and LHT-PO have better redundancy removal properties than other block or lapped transforms. Finally, image compression and noise removal examples are given, showing the advantages of the LHT especially in images containing oriented textures.

  11. LAPS discretization and solution of plasma equilibrium

    NASA Astrophysics Data System (ADS)

    Missanelli, Maria; Delzanno, Gian Luca; Guo, Zehua; Srinivasan, Bhuvana; Tang, Xianzhu

    2011-10-01

    LAPS provides spectral element discretization for solving steady state plasma profiles. Our initial focus is on its implementation for two dimensional open magnetic field equilibria in linear and toroidal geometries. The linear geometry is an axisymmetric magnetic mirror with anisotropic pressure. The toroidal case is a tokamak scrape-off layer plasma. Structured grids are produced by the grid generation package in LAPS. The spectral element discretization uses modal bases over quadrilateral elements. A Newton-Krylov solver implemented with the Portable, Extensible Toolkits for Scientific Computing PETSc is applied to iteratively converge the solution. Care has been taken in the code design to separate the grid generation, spectral element discretization, and (non)linear solver from the user-specified equilibrium equations, so the LAPS infrastructure can be easily used for different applications. Work supported by DOE OFES.

  12. Notebook computer use on a desk, lap and lap support: effects on posture, performance and comfort.

    PubMed

    Asundi, Krishna; Odell, Dan; Luce, Adam; Dennerlein, Jack T

    2010-01-01

    This study quantified postures of users working on a notebook computer situated in their lap and tested the effect of using a device designed to increase the height of the notebook when placed on the lap. A motion analysis system measured head, neck and upper extremity postures of 15 adults as they worked on a notebook computer placed on a desk (DESK), the lap (LAP) and a commercially available lapdesk (LAPDESK). Compared with the DESK, the LAP increased downwards head tilt 6 degrees and wrist extension 8 degrees . Shoulder flexion and ulnar deviation decreased 13 degrees and 9 degrees , respectively. Compared with the LAP, the LAPDESK decreased downwards head tilt 4 degrees , neck flexion 2 degrees , and wrist extension 9 degrees. Users reported less discomfort and difficulty in the DESK configuration. Use of the lapdesk improved postures compared with the lap; however, all configurations resulted in high values of wrist extension, wrist deviation and downwards head tilt. STATEMENT OF RELEVANCE: This study quantifies postures of users working with a notebook computer in typical portable configurations. A better understanding of the postures assumed during notebook computer use can improve usage guidelines to reduce the risk of musculoskeletal injuries.

  13. Translucent titanium coating altered the composition of focal adhesions and promoted migration of osteoblast-like MG-63 cells on glass.

    PubMed

    Ho, Yi; Kok, Sang-Heng; Wang, Juo-Song; Lin, Li-Deh

    2014-04-01

    "TiGlass" was designed and was known to promote initial adhesion and increase migration of rat calvarial osteoblats. In this article, migration study and a series of epifluorescence microscopic studies were conducted to find out the composition of focal adhesion on titanium surface. The translucent titanium surface was applied in random migration analysis and immunofluorescence cell staining. In the immunofluorescent double staining, phosphorylated focal adhesion kinase was tested with vinculin. Various integrin subunits were then tested with vinculin to study the composition of activated focal adhesions. Integrin subunit α5 and αV were tested against β3; integrin subunits α5, αV, β3, and αVβ3 were tested with F-actin, respectively. The MG-63 cells began migration earlier and migrated faster on "TiGlass." Immunofluorescent double staining revealed that all focal adhesion kinase in the focal adhesions were activated on both the surfaces. The osteoblast was inferred to made adhesion to titanium and glass through integrins. The focal adhesions on glass were found to be composed of integrin subunits αV and β3. However, on "TiGlass," integrin subunits α5 might have supplemented the adhesion to titanium. Results from double staining of integrin subunits α5, αV, β3, and αVβ3 with F-actin also supported integrin subunits α5 might have involved in adhesion of titanium.

  14. Even between-lap pacing despite high within-lap variation during mountain biking.

    PubMed

    Martin, Louise; Lambeth-Mansell, Anneliese; Beretta-Azevedo, Liane; Holmes, Lucy A; Wright, Rachel; St Clair Gibson, Alan

    2012-09-01

    Given the paucity of research on pacing strategies during competitive events, this study examined changes in dynamic high-resolution performance parameters to analyze pacing profiles during a multiple-lap mountain-bike race over variable terrain. A global-positioning-system (GPS) unit (Garmin, Edge 305, USA) recorded velocity (m/s), distance (m), elevation (m), and heart rate at 1 Hz from 6 mountain-bike riders (mean±SD age=27.2±5.0 y, stature=176.8±8.1 cm, mass=76.3±11.7 kg, VO2max=55.1±6.0 mL·kg(-1)·min1) competing in a multilap race. Lap-by-lap (interlap) pacing was analyzed using a 1-way ANOVA for mean time and mean velocity. Velocity data were averaged every 100 m and plotted against race distance and elevation to observe the presence of intralap variation. There was no significant difference in lap times (P=.99) or lap velocity (P=.65) across the 5 laps. Within each lap, a high degree of oscillation in velocity was observed, which broadly reflected changes in terrain, but high-resolution data demonstrated additional nonmonotonic variation not related to terrain. Participants adopted an even pace strategy across the 5 laps despite rapid adjustments in velocity during each lap. While topographical and technical variations of the course accounted for some of the variability in velocity, the additional rapid adjustments in velocity may be associated with dynamic regulation of self-paced exercise.

  15. Microleakage evaluation of core buildup composite resins with total-etch and self-etch adhesive systems.

    PubMed

    Moosavi, Horieh; Moazzami, Saieds Mostafa; Loh, Shaghayegh; Salari, Soheil

    2010-03-01

    Core buildup composite resins with prefabricated posts are commonly used to restore endodontically treated teeth. This study compared the sealing ability of Core Max II and Panavia F2.0 cement with total-etch and self-etch adhesive systems. Sixty recently extracted human second premolar teeth were chosen and their crowns were cut 3 mm above the CEJ. After preparing proximal boxes (4+/-1 mm buccolingually and 3 mm occlusogingivally dimensions) and finishing root canal therapy, the teeth were randomly divided into four groups (n=15): groups 1 and 2, Core Max II without and with total-etch adhesive; groups 3 and 4, Clearfil photocore composite, A2 shade, and Panavia F2.0 cement without and with self-etch adhesive respectively. The Dentatus posts (# 2 Long) were used in canals approximately 8 mm depth. According to manufacturer guidelines, pins were cemented and cores were restored. After keeping the specimens for 24 hours at 37 degrees C and 100% humidity, they were thermally cycled for 500 cycles, sealed with nail varnish except 1 mm beyond the margins of restoration, and then immersed in a 0.5% fuschin basic for 24 hours. Samples were embedded in clear epoxy resin, sectioned mesiodistally, and observed at 20x magnification. The microleakage was assessed under stereomicroscope and the results were recorded in percentage of dye penetration to the whole path from the cavosurface margin of the proximal boxes to the end of the post. Analysis of variance and the Tukey test were used to evaluate the data (p=0.05). Groups 1 and 4 had the highest and the lowest values of microleakage respectively. Microleakage of Panavia F2.0 cement was lower than for Core Max II and for both cements using adhesive made the microleakage smaller than without it (p<0.05). Application of adhesive using Core Max II cement and Panavia F2.0 cement is strongly recommended to decrease microleakage. Self-etch adhesive performed better than total-etch adhesive. With regards to microleakage, the self

  16. The effect of sodium hypochlorite on microleakage of composite resin restorations using three adhesive systems.

    PubMed

    Shinohara, Mirela Sanae; Bedran-de-Castro, Ana Karina Barbieri; Amaral, Cristiane Mariote; Pimenta, Luiz André Freire

    2004-01-01

    The aim of this study was to evaluate the effect of three different adhesive systems on microleakage of Class V restorations after the use of sodium hypochlorite. One-hundred eighty bovine incisors were selected and randomly divided into 9 groups (n = 20): G1: Single Bond (SB); G2: 10% NaOCl solution (NS) + SB; G3: 10% NaOCl gel (NG) + SB; G4: Prime & Bond NT (PB); G5: NS + PB; G6: NG + PB; G7: Gluma One Bond (GOB); G8: NS + GOB; G9: NG + GOB. Standardized Class V cavities were prepared. All teeth were etched with 37% phosphoric acid for 15 s. In groups 2, 5, and 8, a 10% NaOCl solution was applied for 60 s to the dentin, and in groups 3, 6, and 9, a 10% NaOCl gel was applied to dentin for 60 s. All cavities were restored with composite resin Definite. The specimens were thermocycled for 1000 cycles (5 degrees C to 55 degrees C) and then immersed in 2% buffered solution of methylene blue for 4 h. The specimens were sectioned and analyzed according to a ranking score (0 to 4). Kruskal-Wallis and Mann-Whitney non-parametric tests (p < or = 0.05) were used for statistical analysis. The NaOCl treatment significantly increased microleakage at the dentin margin (p = 0.0129) as shown by the following sums of ranks: G1 = 1008.0a; G4 = 1301.5ab; G3 = 1687.0ab; G7 = 1744.0bc; G2 = 1802.0c; G9 = 1880.0c; G5 = 1889.0c; G8 = 1950.0c; G6 = 1963.0c (different superscripts indicate significant differences). For enamel, there were no statistically significant differences among the groups (p > 0.05). Depending on the adhesive system used, the application of NaOCl increased microleakage along dentin margins.

  17. Buckling and debond growth of partial debonds in adhesively bonded composite flanges

    NASA Astrophysics Data System (ADS)

    Kwon, Hyukbong

    The strains at which buckling and debond growth occur in adhesively bonded composite flanges containing an initial debond were experimentally measured using sandwich panel and coupon type specimens. Test parameters investigated were: initial debond geometry, the adhesive critical strain energy release rate (Gc), flange material stiffness, and layup sequence. Buckling strains were found to be dependent on initial debond length, flange stiffness and layup sequence. Flanges with a longer initial debond length showed lower buckling strains. Buckling strains increased as the twisting to bending stiffness ratio (D66/D11) increased due to changes in flange layup sequence. Debond growth was found to be strongly dependent on initial debond length but, weakly dependent on flange width. Flanges having higher bending stiffness exhibited a significantly lower debonding strain. Ultrasonic C-scans revealed that debond growth occurred along a curved front, as dictated by the post-buckling deformation of the flanges. Finally, changes in twisting to bending stiffness ratio (D66/D11) due to different flange layup sequences resulted in a variation of post-buckled flange out-of-plane (u3) deformation shape. This was found to affect the debond front shapes as the debond grew. Finite Element Analysis (FEA) based Virtual Crack Closure Technique (VCCT) fracture analysis was conducted. Critical strain energy release rates measured from Double Cantilever Beam (DCB) and Mixed-Mode Fracture (MMF) tests were used as input values and the FEA predictions were shown to be capable of accurately simulating the buckling and debonding behaviors. The FEA study included all the testing parameters investigated in the experiments and also revealed the mode-I, II and III strain energy release rate profiles at the debond front. From the strain energy release rate profiles, fracture mode content and the major fracture mode in each specimen type were clearly understood. The FEA methodology developed within

  18. Bonding of composite resins to PEEK: the influence of adhesive systems and air-abrasion parameters.

    PubMed

    Stawarczyk, Bogna; Taufall, Simon; Roos, Malgorzata; Schmidlin, Patrick R; Lümkemann, Nina

    2017-06-24

    The objective of the study was to investigate the tensile bond strength (TBS) to polyaryletheretherketone (PEEK) after different pretreatment and conditioning methods. Four hundred PEEK specimens were fabricated and allocated to the following air-abrasion methods (n 1 = 80/pretreatment): (i) 50 μm Al2O3 (0.05 MPa); (ii) 50 μm Al2O3 (0.35 MPa); (iii) 110 μm Al2O3 (0.05 MPa); (iv) 110 μm Al2O3 (0.35 MPa); and (v) Rocatec 110 μm (0.28 MPa). These pretreatments were combined with the following conditioning methods (n 2 = 20/pretreatment/conditioning): (a) visio.link (VL); (b) Monobond Plus/Heliobond (MH); (c) Scotchbond Universal (SU); and (d) dialog bonding fluid (DB). After veneering of all specimens with dialog occlusal and aging (28 days H2O, 37 °C + 20,000 thermal cycles, 5/55 °C), TBS was measured. Data was analysed using Kaplan-Meier survival analysis with Breslow-Gehan test and Cox-regressions. The major impact on TBS showed the conditioning, followed by the air-abrasion-pressure, while the grain size of the air-abrasion powder did not show any effect. Specimens air-abraded at 0.35 MPa showed the highest survival rates. However, within VL groups, this observation was not statistically significant. Within MH groups, pretreatment using 110 μm Al2O3 and 0.05 MPa resulted in higher survival rates compared to groups treated with 50 and 110 μm Al2O3 using a pressure of 0.35 MPa. The use of VL showed the highest survival rates between the adhesive systems and the TBS values higher than 25 MPa independent of the pretreatment method. As an exception, only VL showed significantly higher survival rates when compared to MH. The adequate choice of the adhesive system and higher pressures improved the TBS between PEEK and veneering resin composite. The particle size had no major impact. According to this study, best veneering of PEEK with dialog occlusal can be achieved by conditioning with visio.link in combination with the pretreatment of

  19. Experimental study of lap splice bolted connection

    NASA Astrophysics Data System (ADS)

    Zhao, Dehui; Tian, Lishan; Jiang, Wenqiang; An, Liqiang; Zhang, Ziyang

    2017-01-01

    The bolted connection is prone to slip under external load in the lattice transmission tower, which will affect the internal forces and deformation of tower. In order to better simulate the effect of bolt connection slippage on transmission tower, the load deformation relationship should be established. In this paper, the single lap splice bolt connection under tension load is tested and the load displacement curve is obtained. Furthermore, the existing model of single lap splice bolted connection is modified, which will plays an important role in the influence of the bolt slippage of the transmission lines towers more accurately and reasonably.

  20. Adhesion of resin composite to hydrofluoric acid-exposed enamel and dentin in repair protocols.

    PubMed

    Saracoglu, A; Ozcan, M; Kumbuloglu, O; Turkun, M

    2011-01-01

    Intraoral repairs of ceramic fixed-dental-prostheses (FDP) often include cervical recessions that require pretreatment of the exposed tooth surfaces either before or after the ceramic is conditioned with hydrofluoric (HF) acid gel. The sequence of repair protocol may cross-contaminate the exposed etched enamel or dentin surfaces during the application or rinsing process and thereby affect the adhesion. This study evaluated the influence of HF acid gel with two concentrations on bond strengths of composite to enamel and dentin. Human third molars (N=100, n=10 per group) with similar sizes were selected and randomly divided into 10 groups. Flat surfaces of enamel and dentin were created by wet ground finishing. Before or after the enamel (E) or dentin (D) was conditioned with phosphoric acid (P), substrate surfaces were conditioned with either 9.5% HF (HF(9.5)) or 5% HF (HF(5)). Subsequently, a bonding agent (B) was applied. The experimental groups by conditioning sequence were as follows where the first letter of the group abbreviation represents the substrate (E or D) followed by the acid type and concentration: group 1 (EPHF(9.5)), group 2 (EPHF(5)), group 3 (EHF(9.5)P), group 4 (EHF(5)P), group 5 (DPHF(9.5)), group 6 (DPHF(5)), group 7 (DHF(9.5)P), and group 8 (DHF(5)P). Group 9 (EPB) and group 10 (DPB) acted as the control groups. Repair resin was adhered incrementally onto the conditioned enamel and dentin in polyethylene molds. Each layer was photo-polymerized for 40 seconds. All specimens were thermocycled (×1000, 5°-55°C) and subjected to shear test (universal testing machine, 1 mm/min). Specimens that debonded during thermocycling were considered as 0 MPa. The bond strength data were analyzed using Kruskal-Wallis test and failure types using the chi-square test (α=0.05). Overall, the bond results (MPa) were lower on dentin than on enamel (p<0.01). EPB (25.6 ± 6.6) and DPB (20.2 ± 4.9) control groups showed significantly higher results than those of

  1. The effect of acrylic latex-based polymer on cow blood adhesive resins for wood composites

    NASA Astrophysics Data System (ADS)

    Yan, J.; Lin, H. L.; Feng, G. Z.; Gunasekaran, S.

    2016-07-01

    In this paper, alkali-modified cow blood adhesive (BA) and blood adhesive/acrylic latex-based adhesive (BA/ALB) were prepared. The physicochemical and adhesion properties of cow blood adhesive such as UV- visible spectra, particle size, viscosity were evaluated; share strength, water resistance were tested. UV- visible spectra indicates that the strong bonding strength of BA/ALB appeared after incorporating; the particle size of adhesive decreased with the increase of ALB concentration, by mixing ALB and BA, hydrophilic polymer tends locate or extand the protein chains and provide stability of the particles; viscosity decreased as shear rate increased in concordance with a pseudoplastic behavior; both at dry and soak conditions, BA and ALB/BA show significant difference changes when mass fraction of ALB in blend adhesive was over 30% (p < 0.05). ALB/ BA (ALB30%) is not significant different than that of phenol formaldehyde which was used as control. A combination of cow blood and acrylic latex-based adhesive significantly increased the strength and water resistance of the resulting wood.

  2. Stress distributions in adhesively cemented ceramic and resin-composite Class II inlay restorations: a 3D-FEA study.

    PubMed

    Ausiello, Pietro; Rengo, Sandro; Davidson, Carel L; Watts, David C

    2004-11-01

    The purpose of this study was to investigate the effect of differences in the resin-cement elastic modulus on stress-transmission to ceramic or resin-based composite inlay-restored Class II MOD cavities during vertical occlusal loading. Three finite-element (FE) models of Class II MOD cavity restorations in an upper premolar were produced. Model A represented a glass-ceramic inlay in combination with an adhesive and a high Young's modulus resin-cement. Model B represented the same glass-ceramic inlay in combination with the same adhesive and a low Young's modulus resin-cement. Model C represented a heat-cured resin-composite inlay in combination with the same adhesive and the same low Young's modulus resin cement. Occlusal vertical loading of 400 N was simulated on the FE models of the restored teeth. Ansys FE software was used to compute the local von Mises stresses for each of the models and to compare the observed maximum intensities and distributions. Experimental validation of the FE models was conducted. Complex biomechanical behavior of the restored teeth became apparent, arising from the effects of the axial and lateral components of the constant occlusal vertical loading. In the ceramic-inlay models, the greatest von Mises stress was observed on the lateral walls, vestibular and lingual, of the cavity. Indirect resin-composite inlays performed better in terms of stress dissipation. Glass-ceramic inlays transferred stresses to the dental walls and, depending on its rigidity, to the resin-cement and the adhesive layers. For high cement layer modulus values, the ceramic restorations were not able to redistribute the stresses properly into the cavity. However, stress-redistribution did occur with the resin-composite inlays. Application of low modulus luting and restorative materials do partially absorb deformations under loading and limit the stress intensity, transmitted to the remaining tooth structures.

  3. Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements

    PubMed Central

    PAMIR, Tijen; ŞEN, Bilge Hakan; EVCIN, Özgür

    2012-01-01

    Objective This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements. Material and Methods Conventional (KetacTM Molar Quick ApplicapTM) or resin-modified (PhotacTM Fil Quick AplicapTM) glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (AdperTM Single Bond 2) or single-step self-etching adhesive (AdperTM PromptTM L-PopTM) was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1) no etching, (2) 15 s of etching with 35% phosphoric acid, (3) 30 s of etching, and (4) 60 s of etching. Following the placement of the composite resin (FiltekTM Z250), the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA) followed by the Tukey's HSD post hoc analysis (p=0.05). Then, the fractured surfaces were examined by scanning electron microscopy. Results The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p<0.001). No significant differences were determined between the self-etching and etch-rinse & bond adhesives at any etching time (p>0.05). However, a greater bond strength was obtained with 30 s of phosphoric acid application. Conclusions The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal. PMID:23329245

  4. Select aspects of FEM analysis for bonded joints of polymer composite materials

    NASA Astrophysics Data System (ADS)

    Rudawska, A.

    2015-07-01

    The paper presents selected aspects of modelling bonded joints of polymer composite materials by finite element method. The shear-loaded adhesive lap joints made of epoxy-graphite and epoxy-glass composite materials were investigated. The research objective was to determine correct modelling of adhesive layers using cohesive elements and of bonded joints for selected epoxy composite materials with different mechanical properties (e.g. Young's modulus) and geometrical dimensions, using, however, the same type of adhesive. The numerical analysis was performed based on experimental tests. A comparison is made between the distribution of reduced stress in the examined joint models according to the H-M- H hypothesis and that determined according to the maximum principal stress hypothesis. The finite elements analysis was performed in ABAQUS software and the traction-separation failure criterion was used for the damage onset and growth in the adhesive layer.

  5. Two-year clinical performance of self-etching adhesive systems in composite restorations of anterior teeth.

    PubMed

    Barcellos, D C; Batista, G R; Silva, M A; Pleffken, P R; Rangel, P M; Fernandes, V V B; Di Nicoló, R; Torres, C R G

    2013-01-01

    The aim of this study was to evaluate the two-year clinical performance of Class III, IV, and V composite restorations using a two-step etch-and-rinse adhesive system (2-ERA) and three one-step self-etching adhesive systems (1-SEAs). Two hundred Class III, IV, and V composite restorations were placed into 50 patients. Each patient received four composite restorations (Amaris, Voco), and these restorations were bonded with one of three 1-SEAs (Futurabond M, Voco; Clearfil S3 Bond, Kuraray; and Optibond All-in-One, Kerr) or one 2-ERA (Adper Single Bond 2/3M ESPE). The four adhesive systems were evaluated at baseline and after 24 months using the following criteria: restoration retention, marginal integrity, marginal discoloration, caries occurrence, postoperative sensitivity and preservation of tooth vitality. After two years, 162 restorations were evaluated in 41 patients. Data were analyzed using the χ(2) test (p<0.05). There were no statistically significant differences between the 2-ERA and the 1-SEAs regarding the evaluated parameters (p>0.05). The 1-SEAs showed good clinical performance at the end of 24 months.

  6. Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Barclay, D. L.

    1980-01-01

    Results of an experimental program to develop several types of graphite/polyimide (GR/PI) bonded and bolted joints for lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Tasks accomplished include: a literature survey; design of static discriminator specimens; design allowables testing; fabrication of test panels and specimens; small specimen testing; and standard joint testing. Detail designs of static discriminator specimens for each of the four major attachment types are presented. Test results are given for the following: (1) transverse tension of Celion 3000/PMR-15 laminate; (2) net tension of a laminate for both a loaded and unloaded bolt hole; (3) comparative testing of bonded and co-cured doublers along with pull-off tests of single and double bonded angles; (4) single lap shear tests, transverse tension and coefficient of thermal expansion tests of A7F (LARC-13 amide-imide modified) adhesive; and (5) tension tests of standard single lap, double lap, and symmetric step lap bonded joints. Also, included are results of a finite element analysis of a single lap bonded composite joint.

  7. Effect of dentin dehydration and composite resin polymerization mode on bond strength of two self-etch adhesives.

    PubMed

    Samimi, Pooran; Alizadeh, Mehdi; Shirban, Farinaz; Davoodi, Amin; Khoroushi, Maryam

    2016-01-01

    Dual-cured composite resins are similar to self-cured composite resins in some of their clinical applications due to inadequate irradiation, lack of irradiation, or delayed irradiation. Therefore, incompatibility with self-etch adhesives (SEAs) should be taken into account with their use. On the other, the extent of dentin dehydration has a great role in the quality of adhesion of these resin materials to dentin. The aim of this study was to investigate the effect of dentin dehydration and composite resin polymerization mode on bond strength of two SEAs. A total of 120 dentinal specimens were prepared from extracted intact third molars. Half of the samples were dehydrated in ethanol with increasing concentrations. Then Clearfil SE Bond (CSEB) and Prompt L-Pop (PLP) adhesives were applied in the two groups. Cylindrical composite resin specimens were cured using three polymerization modes: (1) Immediate light-curing, (2) delayed light-curing after 20 min, and (3) self-curing. Bond strength was measured using universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and Duncan post hoc tests. Statistical significance was defined at P < 0.05. There were no significant differences for CSEB subgroups with hydrated and dehydrated dentin samples between the three different curing modes (P > 0.05). PLP showed significant differences between subgroups with the lowest bond strength in hydrated dentin with delayed light-curing and self-cured mode of polymerization. Within the limitations of this study, a delay in composite resin light-curing or using chemically cured composite resin had a deleterious effect on dentin bond strength of single-step SEAs used in the study.

  8. Effect of dentin dehydration and composite resin polymerization mode on bond strength of two self-etch adhesives

    PubMed Central

    Samimi, Pooran; Alizadeh, Mehdi; Shirban, Farinaz; Davoodi, Amin; Khoroushi, Maryam

    2016-01-01

    Background: Dual-cured composite resins are similar to self-cured composite resins in some of their clinical applications due to inadequate irradiation, lack of irradiation, or delayed irradiation. Therefore, incompatibility with self-etch adhesives (SEAs) should be taken into account with their use. On the other, the extent of dentin dehydration has a great role in the quality of adhesion of these resin materials to dentin. The aim of this study was to investigate the effect of dentin dehydration and composite resin polymerization mode on bond strength of two SEAs. Materials and Methods: A total of 120 dentinal specimens were prepared from extracted intact third molars. Half of the samples were dehydrated in ethanol with increasing concentrations. Then Clearfil SE Bond (CSEB) and Prompt L-Pop (PLP) adhesives were applied in the two groups. Cylindrical composite resin specimens were cured using three polymerization modes: (1) Immediate light-curing, (2) delayed light-curing after 20 min, and (3) self-curing. Bond strength was measured using universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and Duncan post hoc tests. Statistical significance was defined at P < 0.05. Results: There were no significant differences for CSEB subgroups with hydrated and dehydrated dentin samples between the three different curing modes (P > 0.05). PLP showed significant differences between subgroups with the lowest bond strength in hydrated dentin with delayed light-curing and self-cured mode of polymerization. Conclusion: Within the limitations of this study, a delay in composite resin light-curing or using chemically cured composite resin had a deleterious effect on dentin bond strength of single-step SEAs used in the study. PMID:27041894

  9. The effect of adhesive systems on the pullout strength of a fiberglass-reinforced composite post system in bovine teeth.

    PubMed

    Valandro, Luiz Felipe; Filho, Osvaldo Daniel Andreatta; Valera, Márcia Carneiro; de Araujo, Maria Amélia Maximo

    2005-01-01

    To evaluate the pullout strength of a glass fiber-reinforced composite post (glass FRC) cemented with three different adhesive systems and one resin cement. The null hypothesis was that pullout strengths yielded by the adhesive systems are similar. Thirty bovine teeth were selected. The size of the specimens was standardized at 16 mm by sectioning off the coronal portion and part of the root. The specimens were divided into three groups, according to the adhesive system, which were applied following the manufacturers' instructions: G1, ScotchBond Multi-Purpose Plus; G2, Single Bond; G3, Tyrian SPE/One-Step Plus. The glass FRCs (Reforpost) were etched with 37% H3PO4 for 1 min and silanized (Porcelain Primer). Thereafter, they were cemented with the dual resin cement En-Force. The specimens were stored for 24 h, attached to an adapted device, and submitted to the pullout test in a universal testing machine (1 mm/min). The data were submitted to the one-way ANOVA and Tukey's test (alpha = 0.05). G1 (30.2 +/- 5.8 Kgf) displayed the highest pullout strength (p < 0.001) when compared to G2 (18.6 +/- 5.8 Kgf) and G3 (14.3 +/- 5.8 Kgf), which were statistically similar. Analysis of the specimens revealed that all failures occurred between the adhesive system and the root dentin (pullout of the post cement), regardless of group. The multiple-bottle, total-etch adhesive system provided higher pullout strength of the glass FRC when compared to the single-bottle, total-etch, and single-step self-etching adhesive systems. The null hypothesis was rejected (p < 0.001).

  10. Bond Strength of Resin Composite to Dentin with Different Adhesive Systems: Influence of Relative Humidity and Application Time.

    PubMed

    Amsler, Fabienne; Peutzfeldt, Anne; Lussi, Adrian; Flury, Simon

    2015-06-01

    To investigate the influence of relative humidity and application time on bond strength to dentin of different classes of adhesive systems. A total of 360 extracted human molars were ground to mid-coronal dentin. The dentin specimens were treated with one of six adhesive systems (Syntac Classic, OptiBond FL, Clearfil SE Bond, AdheSE, Xeno Select, or Scotchbond Universal), and resin composite (Filtek Z250) was applied to the treated dentin surface under four experimental conditions (45% relative humidity/application time according to manufacturers' instructions; 45% relative humidity/reduced application time; 85% relative humidity/application time according to manufacturers' instructions; 85% relative humidity/reduced application time). After storage (37°C, 100% humidity, 24 h), shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA followed by Kruskal-Wallis tests and Mann-Whitney U-tests with Bonferroni-Holm correction for multiple testing (level of significance: α = 0.05). Increased relative humidity and reduced application time had no effect on SBS for Clearfil SE Bond and Scotchbond Universal (p = 1.00). For Syntac Classic, OptiBond FL, AdheSE, and Xeno Select there was no effect on SBS of reduced application time of the adhesive system (p ≥ 0.403). However, increased relative humidity significantly reduced SBS for Syntac Classic, OptiBond FL, and Xeno Select irrespective of application time (p ≤ 0.003), whereas for AdheSE, increased relative humidity significantly reduced SBS at recommended application time only (p = 0.002). Generally, increased relative humidity had a detrimental effect on SBS to dentin, but reduced application time had no effect.

  11. A two-dimensional stress analysis of single lap joints subjected to external bending moments

    SciTech Connect

    Sawa, Toshiyuki; Nakano, Katsuyuki; Toratani, Hiroshi

    1995-11-01

    The stress distribution of single lap adhesive joints subjected to external bending moments are analyzed as a three-body contact problem by using a two-dimensional theory of elasticity. In the analysis, two similar adherends and an adhesive are replaced by finite strips, respectively. In the numerical calculations, the effects of the ratio of Young;s modulus of adherends to that of adhesive and the adhesive thickness on the stress distribution at the interface are examined. As the results, it is seen that the stress singularity causes at the edges of the interfaces and the peel stress at the edges of the interface increases with a decrease of Young`s modulus of the adherends. In addition, photoelastic experiments are carried out. A fairly good agreement is seen between the analytical and the experimental results.

  12. Effect of postoperative peroxide bleaching on the marginal seal of composite restorations bonded with self-etch adhesives.

    PubMed

    Roubickova, A; Dudek, M; Comba, L; Housova, D; Bradna, P

    2013-01-01

    The aim of this study was to determine the effect of peroxide bleaching on the marginal seal of composite restorations bonded with several adhesive systems. Combined cylindrical Class V cavities located half in enamel and half in dentin were prepared on the buccal and lingual surfaces of human molars. The cavities were bonded with the self-etch adhesives Clearfil SE-Bond (CLF), Adper Prompt (ADP), and iBond (IBO) and an etch-and-rinse adhesive Gluma Comfort Bond (GLU) and restored with a microhybrid composite Charisma. Experimental groups were treated 25 times for eight hours per day with a peroxide bleaching gel Opalescence PF 20, while the control groups were stored in distilled water for two months and then subjected to a microleakage test using a dye penetration method. Scanning electron microscopy was used to investigate the etching and penetration abilities of the adhesives and morphology of debonded restoration-enamel interfaces after the microleakage tests. Statistical analyses were performed using nonparametric Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests at p=0.05. The microleakage of all GLU groups was low and not significantly affected by peroxide bleaching. Low microleakage was recorded for CLF control groups, but after bleaching, a small but significant increase in microleakage at the enamel margin indicated its sensitivity to peroxide bleaching. For ADP and IBO control groups, the microleakage at the enamel margins was significantly higher than for GLU and CLF and exceeded that at the dentin margins. Bleaching did not induce any significant changes in the microleakage. Electron microscopy analysis indicated that in our experimental setup, decreased adhesion and mechanical resistance of the ADP- and IBO-enamel interfaces could be more important than the chemical degradation effects induced by the peroxide bleaching gel.

  13. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Lap-joint seam boilers. 230.30 Section 230.30..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal...

  14. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Lap-joint seam boilers. 230.30 Section 230.30..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal...

  15. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Lap-joint seam boilers. 230.30 Section 230.30..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal...

  16. The influence of alloy composition on anaerobic adhesives in dental bonding.

    PubMed

    Ireland, A J; Sherriff, M

    1998-11-01

    Single-component anaerobic adhesives are in common use in the electronics and engineering industries. They are generally diacrylate monomers which do not require conventional sources of heat, light or chemicals for activation. Their advantages include activation by the bonding substrate, as well as inhibition of polymerisation until the necessary anaerobic environment is created. The aim of this experiment was to determine whether metal attachments could be successfully bonded to enamel in vitro by such adhesives. Metal attachments capable of providing an anaerobic environment were fabricated from one of three alloys: stainless steel, copper or cobalt-chromium. They were bonded to prepared human enamel with one of four adhesives: Orthodontic Concise, as a control, and three anaerobic adhesives, Perma Metal, Permabond A134 and Loctite 326. The specimens were then bond tested in shear to failure after bench curing for one of four time periods. The results were analysed in terms of mean force to debond (N) and 95% confidence intervals. Kaplan-Meier survival probabilities and log-rank tests were performed for the 10 min test times. Both Orthodontic Concise and the three anaerobic adhesives displayed a specificity towards different attachment alloys. Whereas Orthodontic Concise displayed the highest force to debond with stainless steel attachments, for the anaerobic adhesives this was true of the copper attachments. With stainless steel attachments, however, the force to debond with the anaerobic adhesives was similar to that observed with Orthodontic Concise and steel, at least after the relatively short 10 min bench curing time.

  17. Black Silicon/Elastomer Composite Surface with Switchable Wettability and Adhesion between Lotus and Rose Petal Effects by Mechanical Strain.

    PubMed

    Park, Jun Kyu; Yang, Zining; Kim, Seok

    2017-09-13

    Although many recent studies demonstrate surfaces with switchable wettability under various external stimuli, a deliberate effort to self-propel liquid droplets utilizing a surface wetting mode switch between slippery lotus and adhesive rose petal states via a mechanical strain has not been made yet, which would otherwise further benefit microfluidic applications. In this work, we present a black silicon/elastomer (bSi/elastomer) composite surface which shows switchable wettability and adhesion across the two wetting modes by mechanical stretching. The composite surface is composed of a scale-like nanostructured silicon platelet array that covers an elastomer surface. The gap between the neighboring silicon platelets is reversibly changeable as a function of a mechanical strain, leading to the transition between the two wetting modes. Moreover, the composite surface is highly flexible although its wetting properties primarily originate from superhydrophobic bSi platelets. Different wetting characteristics of the composite surface in various mechanical strains are studied, and droplet manipulation such as droplet self-propulsion and pick-and-place using the composite surface is demonstrated, which highlights its potentials for microfluidic applications.

  18. Composite resin's adhesive resistance to dentin: influence of Er:YAG laser focal distance variation.

    PubMed

    Corona, Silmara Aparecida Milori; Atoui, Juliana Abdallah; Chimello, Daniela Thomazatti; Borsatto, Maria Cristina; Pecora, Jesus Djalma; Dibb, Regina Guenka Palma

    2005-04-01

    The aim of this study was to analyze in vitro the influence of Er:YAG laser focal distance variation on tensile bond strength of a composite resin to dentin. Although there are several studies using the Er:YAG laser for dentin treatment, there is a lack of available literature related to the Er:YAG laser focal distance variation. Sixty vestibular and lingual dentin surfaces from extracted human third molars, kept in a 0.4% azide sodium solution, were ground and assigned to six groups. The control group was conditioned with 35% phosphoric acid (CA). In the lased groups, the dentin surface treatment was performed by irradiation with Er:YAG laser (80 mJ/2 Hz), varying the focal distance (11, 12, 14, 16, and 17 mm), followed by acid etching. The Single Bond/Filtek Z250 (3M) resinous system was used for the specimen manufacture. The tensile bond strength tests were performed in a Universal Testing Machine with 50 kgf load cell and 0.5 mm/min cross head speed. The averages in MPa were: CA: 18.03 (+/-2.09); 11 mm; 9.92 (+/-3.34); 12 mm: 9.49 (+/-2.29); 14 mm: 10.99 (+/-3.45); 16 mm: 10.56 (+/-1.93); and 17 mm: 17.05 (+/-2.31). It was concluded that the application of Er:YAG laser in a defocused mode (17 mm) associated with acid etching was similar to the treatment of acid solely. Er:YAG laser irradiation in a focused (12 mm) and a defocused (11, 14, and 16 mm) mode coupled with acid conditioning produced the lowest values of adhesion.

  19. Glass fibre-reinforced composite laced with chlorhexidine digluconate and yeast adhesion.

    PubMed

    Waltimo, T; Luo, G; Samaranayake, L P; Vallittu, P K

    2004-02-01

    The aim of this study was to lace dental glass fibre reinforced composite (FRC) prepreg with chlorhexidine digluconate and to examine the adherence of common oral fungal pathogen Candida albicans to FRC made of the prepreg. Four different test and control material groups each comprising 16 test specimens ((5.0 x 5.0 x 0.8) mm3) each were used as substrates for C. albicans adherence. A porous polymer pre-impregnated woven glass fibre prepreg was laced with solution of chlorhexidine gluconate and it was used with autopolymerized denture base polymer to fabricate FRC test specimens. Control group (Group 1) consisted of FRC test specimens stored in water. In Group 2, the test specimens were stored in 10% chlorhexidine digluconate solution for 24 h. Group 3 consisted of specimens fabricated using such fibre reinforcements which were pre-soaked in 20% chlorhexidine digluconate and dried before preparation with denture base resin, and followed by storage of the specimens in water. Group 4 was similar to Group 3 but instead of water storage the specimens were immersed in 10% chlorhexidine digluconate for 24 h. For the candidal adhesion assay the test and control specimens were incubated in standardized suspensions of four different strains of C. albicans, rinsed and prepared for light-microscopy. The mean number of adherent cells in each group was counted microscopically and analysed statistically. There were significantly (P < 0.05) more adherent C. albicans cells found in Group 1 than in the other three groups which did not differ significantly from each other. The lowest numbers of adherent cells were found in Group 3. Pretreating the porous polymer pre-impregnated glass fibre reinforcement with chlorhexidine digluconate result in reduction in the number of adherent yeast cells on the surface FRC material.

  20. Three-dimensional finite element analysis of strength and adhesion of composite resin versus ceramic inlays in molars.

    PubMed

    Dejak, Beata; Mlotkowski, Andrzej

    2008-02-01

    Previous studies on strength of teeth reconstructed with ceramic or composite resin inlays have not resolved which restoration material provides the highest strength and marginal integrity. The purpose of this study was to compare strength of mandibular molars restored with composite resin inlays to those restored with ceramic inlays, according to the Mohr-Coulomb failure criterion, and to analyze contact stresses in cement-tooth adhesive interfaces of these inlays. The investigation used a 3-dimensional (3-D) finite element analysis with the use of contact elements. Seven 3-D models of first molars of the same shape and size were created: IT, intact tooth; UT, unrestored tooth with an MOD cavity preparation; CRIT, tooth restored with composite resin inlays (True Vitality) with an elastic modulus equal to 5.4 GPa; CRIH, tooth restored with composite resin inlays (Herculite XRV) (9.5 GPa); CRIC, tooth restored with composite resin inlays (Charisma) (14.5 GPa); CRIZ, tooth restored with composite resin inlays (Z100) (21 GPa); and CI, tooth restored with a ceramic (IPS Empress) inlay with an elastic modulus equal to 65 GPa. Each model was subjected to a force of 200 N directed to the occlusal surface. The stresses occurring in the tested inlays, composite resin cement layer, and tooth tissues were calculated. To evaluate the strength of materials, the Mohr-Coulomb failure criterion was used. Contact stresses in the cement-tissue adhesive interface were calculated and compared to tensile and shear bond strength of the luting cement to enamel and dentin. In the teeth restored with composite resin and ceramic inlays, the values of the Mohr-Coulomb failure criterion were lower than in the unrestored tooth with a preparation (UT), but still 2.5 times higher than in the intact tooth (IT). For the ceramic inlay (CI), the values of the Mohr-Coulomb failure criterion were nearly 3 times higher than in the composite resin inlays. For the luting agent for the ceramic inlay model

  1. Five-year clinical performance of a silorane- vs a methacrylate-based composite combined with two different adhesive approaches.

    PubMed

    Baracco, Bruno; Fuentes, M Victoria; Ceballos, Laura

    2016-06-01

    The objective of this study was to compare the 5-year clinical performance in posterior restorations of three restorative systems including a low-shrinkage system and a methacrylate-based composite combined either with an etch-and-rinse or a self-etch adhesive. Each of 25 patients received three class I (occlusal) or class II restorations performed with each one of the three restorative systems: Filtek Silorane Restorative System including a two-step self-etch adhesive, Adper Scotchbond 1 XT (two-step etch-and-rinse adhesive) + Filtek Z250, and Adper Scotchbond SE (two-step self-etch adhesive) + Filtek Z250. All materials were applied as per manufacturer's instructions. Two blind observers evaluated the restorations at four different moments (baseline, after 1, 2, and 5 years) according to the USPHS-modified criteria. Kruskal-Wallis and Mann-Whitney U tests were conducted to compare the behavior of the restorative systems, while Friedman and Wilcoxon tests were applied to analyze the intrasystem data (p < 0.05). After 5 years, marginal staining around the restorations with Adper Scotchbond SE + Filtek Z250 was statistically more frequent and severe than that of the restorations performed with the other two systems. Intrasystem comparisons revealed a deterioration of the marginal adaptation after 5 years for all systems. A significant number of restorations bonded with self-etch adhesives showed marginal staining after 5 years of clinical service. A deterioration of the color appearance and an increase of the surface roughness were also detected in the restorations performed with Adper Scotchbond SE + Filtek Z250. A deterioration of the marginal adaptation was evidenced for all restorative systems, while marginal staining was more frequently seen only around the restorations performed with self-etch adhesives. No advantage was found of the silorane- over the methacrylate-based composite when combined with an etch-and-rinse adhesive.

  2. A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics

    NASA Technical Reports Server (NTRS)

    Dwight, D. W.; Wightman, J. P.

    1977-01-01

    The ability of SEM/EDAX to determine the physical and chemical composition of very small areas was used to study several diverse types of samples representative of NASA-LaRC technology. More systematic investigation was carried out on differences in the results of grit-blasting Ti 6-4 adherends and the presence of extraneous elements, primarily silicon, in some polymer/HT-S fiber composites. Initial results were obtained from a fractured (ILS) short-beam shear specimen, and from Ti 6-4 alloy, before and after a proprietary Boeing anodizing surface preparation for adhesive bonding. Photomicrographs and EDAX spectra were also obtained from new, fractured lap shear strength specimens that employed PPQ and LARC-13 adhesives.

  3. The development of autoclave processable, thermally stable adhesives for titanium alloy and graphite composite structures

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Jones, R. J.

    1971-01-01

    The A-type polyimide adhesive resin P11B was modified by use of mixed diamines (thio-dianiline and meta phenylene diamine) which provided the desired autoclave processability. This new resin was termed P11BA. It was shown that copolymeric blends of P11BA and Amoco AI-1137 amide-imide resin provided improved adhesive properties when autoclave processed over the properties obtained previously by press bonding with P11B based copolymeric blended adhesives. Properties of bonded assemblies are presented for long-term aging at both elevated and low temperatures, and also stress-rupture tests at elevated temperature.

  4. Lindsey with lap top in the Spacehab

    NASA Image and Video Library

    1998-11-04

    STS095-E-5218 (4 Nov. 1998) --- Astronaut Steven W. Lindsey, STS-95 pilot, inputs data on a lap top computer in the Spacehab facility onboard the Space Shuttle Discovery. The photo was taken with an electronic still camera (ESC) at 02:58:43 GMT, Nov. 4.

  5. Shear Bond Strength of Calcium Enriched Mixture Cement and Mineral Trioxide Aggregate to Composite Resin with Two Different Adhesive Systems

    PubMed Central

    Savadi Oskoee, Siavash; Bahari, Mahmoud; Kimyai, Soodabeh; Motahhari, Paria; Eghbal, Mohammad Jafar; Asgary, Saeed

    2014-01-01

    Objective: Immediate restoration after vital pulp therapy is essential in order to create and maintain effective coronal seal. Purpose of Study: The aim of this study was to evaluate the shear bond strength of recently used pulp capping materials: white mineral trioxide aggregate (MTA), and calcium enriched mixture cement (CEM) to composite resin with the use of etch-and-rinse and self-etch adhesive systems and compare them with the bond strength of commonly used resin modified glass ionomer (RMGI) cement. Materials and Methods: Forty specimens from each test material were fabricated, measuring 4 mm in diameter and 2 mm in depth. The specimens of each material were divided into 2 groups of 20 specimens according to the adhesive system (Single Bond vs. Clearfil SE Bond) used for bonding of resin composite. The shear bond strength values were measured at a crosshead speed of 1.0 mm/min and fractured surfaces were examined. Data were analyzed using two-way ANOVA and a post hoc Tukey’s test (P<0.05). Results: Analysis of data showed a significantly higher bond strength for RMGI compared to MTA and CEM (P<0.001); however, no significant differences were observed in the bond strength values of MTA and CEM (P=0.9). Furthermore, there were no significant differences in relation to the type of the adhesive system irrespective of the type of the material used (P=0.95) All the failures were of cohesive type in RMGI, MTA and CEM. Conclusion: Bond strength of RMGI cement to composite resin was higher than that of MTA or CEM cement irrespective of the type of the adhesive system. PMID:25628696

  6. MAPs/bFGF-PLGA microsphere composite-coated titanium surfaces promote increased adhesion and proliferation of fibroblasts.

    PubMed

    Wang, Zhongshan; Wu, Guofeng; Bai, Shizhu; Feng, Zhihong; Dong, Yan; Zhou, Jian; Qin, Haiyan; Zhao, Yimin

    2014-06-01

    Infection and epithelial downgrowth are two major problems with maxillofacial transcutaneous implants, and both are mainly due to lack of stable closure of soft tissues at transcutaneous sites. Fibroblasts have been shown to play a key role in the formation of biological seals. In this work, titanium (Ti) model surfaces were coated with mussel adhesive proteins (MAPs) utilizing its unique adhesion ability on diverse inorganic and organic surfaces in wet environments. Prepared basic fibroblast growth factor (bFGF)-poly(lactic-co-glycolic acid) (PLGA) microspheres can be easily synthesized and combined onto MAPs-coated Ti surfaces, due to the negative surface charges of microspheres in aqueous solution, which is in contrast to the positive charges of MAPs. Titanium model surfaces were divided into three groups. Group A: MAPs/bFGF-PLGA microspheres composite-coated Ti surfaces. Group B: MAPs-coated Ti surfaces. Group C: uncoated Ti surfaces. The effects of coated Ti surfaces on adhesion of fibroblasts, cytoskeletal organization, proliferation, and extracellular matrix (ECM)-related gene expressions were examined. The results revealed increased adhesion (P < 0.05), enhanced actin cytoskeletal organization, and up-regulated ECM-related gene expressions in groups A and B compared with group C. Increased proliferation of fibroblasts during five days of incubation was observed in group A compared with groups B and C (P < 0.05). Collectively, the results from this in vitro study demonstrated that MAPs/bFGF-PLGA microspheres composite-coated Ti surfaces had the ability to increase fibroblast functionality. In addition, MAPs/bFGF-PLGA microsphere composite-coated Ti surfaces should be studied further as a method of promoting formation of stable biological seals around transcutaneous sites.

  7. Improved enrichment culture technique for methane-oxidizing bacteria from marine ecosystems: the effect of adhesion material and gas composition.

    PubMed

    Vekeman, Bram; Dumolin, Charles; De Vos, Paul; Heylen, Kim

    2017-02-01

    Cultivation of microbial representatives of specific functional guilds from environmental samples depends largely on the suitability of the applied growth conditions. Especially the cultivation of marine methanotrophs has received little attention, resulting in only a limited number of ex situ cultures available. In this study we investigated the effect of adhesion material and headspace composition on the methane oxidation activity in methanotrophic enrichments obtained from marine sediment. Addition of sterilized natural sediment or alternatively the addition of acid-washed silicon dioxide significantly increased methane oxidation. This positive effect was attributed to bacterial adhesion on the particles via extracellular compounds, with a minimum amount of particles required for effect. As a result, the particles were immobilized, thus creating a stratified environment in which a limited diffusive gas gradients could build up and various microniches were formed. Such diffusive gas gradient might necessitate high headspace concentrations of CH4 and CO2 for sufficient concentrations to reach the methane-oxidizing bacteria in the enrichment culture technique. Therefore, high concentrations of methane and carbon dioxide, in addition to the addition of adhesion material, were tested and indeed further stimulated methane oxidation. Use of adhesion material in combination with high concentrations of methane and carbon dioxide might thus facilitate the cultivation and subsequent enrichment of environmentally important members of this functional guild. The exact mechanism of the observed positive effects on methane oxidation and the differential effect on methanotrophic diversity still needs to be explored.

  8. Composites for Advanced Space Transportation Systems - (CASTS). [graphite fiber/polyimide matrix composites and polyimide adhesives for the space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Davis, J. G., Jr.

    1979-01-01

    The CASTS Project initiated to develop graphite fiber/polyimide matrix (GR/PI) composite structures with 589K operational capability for aerospace vehicles is described. Near term tasks include screening composites and adhesives for 589K service, developing fabrication procedures and specifications, developing design allowables test methods and data, design and test of structural elements, and construction of a full scale aft body flap for the space shuttle orbiter vehicle for ground testing. Far term tasks include research efforts directed at new materials, manufacturing procedures and design/analysis methodology. Specific results discussed include: (1) identification of four GR/PI composites and three PI adhesives with 589K service potential for periods ranging from 125 to 500 hours; (2) development of an adhesive formulation suitable for bonding reusable surface insulation (RSI) titles to 589K (GR/PI) substructure; (3) the capability to fabricate and nondestructively inspect laminates, hat section shaped stiffeners, honeycomb sandwich panels, and chopped fiber moldings; and (4) test methods for measuring design allowables at 117K.

  9. Composites for Advanced Space Transportation Systems - (CASTS). [graphite fiber/polyimide matrix composites and polyimide adhesives for the space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Davis, J. G., Jr.

    1979-01-01

    The CASTS Project initiated to develop graphite fiber/polyimide matrix (GR/PI) composite structures with 589K operational capability for aerospace vehicles is described. Near term tasks include screening composites and adhesives for 589K service, developing fabrication procedures and specifications, developing design allowables test methods and data, design and test of structural elements, and construction of a full scale aft body flap for the space shuttle orbiter vehicle for ground testing. Far term tasks include research efforts directed at new materials, manufacturing procedures and design/analysis methodology. Specific results discussed include: (1) identification of four GR/PI composites and three PI adhesives with 589K service potential for periods ranging from 125 to 500 hours; (2) development of an adhesive formulation suitable for bonding reusable surface insulation (RSI) titles to 589K (GR/PI) substructure; (3) the capability to fabricate and nondestructively inspect laminates, hat section shaped stiffeners, honeycomb sandwich panels, and chopped fiber moldings; and (4) test methods for measuring design allowables at 117K.

  10. [Pre-treatment of dental alloy for adhesive restorations. Part 3. Alkyl ammonium/Sn composite plating to various dental alloys].

    PubMed

    Kondo, Y; Yamashita, A; Suzuki, K; Omura, I; Yamauchi, J

    1989-01-01

    The effect of alkyl ammonium salt/Sn composite plating on the adhesive characteristics of dental alloys was examined. The surface of dental alloys, on which such a composite plating was made, was analyzed by ESCA. The effect of the length of alkyl chain and its terminal atomic groups on the tensile adhesive strength to an adhesive resin was also examined. ESCA analysis revealed that both C and N atoms from the alkyl ammonium salts were certified on the surface of the dental alloys. Stable tensile adhesive strength, as high as 500 kg/cm2, was obtained when the number of C atoms of alkyl chain was 10 to 16. The alkyl ammonium salts containing such groups as hydroxyl, amino and vinyl at the terminal of the alkyl chain, were effective for increasing the tensile adhesive strength.

  11. Fatigue strength of a single lap joint SPR-bonded

    SciTech Connect

    Di Franco, G.; Fratini, L.; Pasta, A.

    2011-05-04

    In the last years, hybrid joints, meaning with this the joints which consist in combining a traditional mechanical joint to a layer of adhesive, are gradually attracting the attention of various sectors of the construction of vehicles and transportation industries, for their better performance compared to just mechanical joints (self-piercing riveting SPR, riveting, and so on) or just to bonded joints.The paper investigates the fatigue behavior of a single lap joint self-piercing riveted (SPR) and bonded throughout fatigue tests. The considered geometric configuration allowed the use of two rivets placed longitudinally; an epoxy resin was used as adhesive. In the first part of the work static characterization of the joints was carried out through tensile tests. Then fatigue tests were made with the application of different levels of load. The fatigue curves were also obtained at the varying the distance between the two rivets in order to better assess the joint strength for a given length of overlap.

  12. Efficacy of Hydrophobic Layer on Sealing Ability of Dentin Adhesive Systems in Class V Composite Resin Restorations

    PubMed Central

    Maleknejad, Fatemeh; Moazzami, Saied Mostafa; Baradaran Nasseri, Elham; Baradaran Nasseri, Ehsan

    2011-01-01

    Background and aims Adhesive permeability is hindered by application of an additional layer of hydrophobic resin, which increases its concentration within the hydrophilic layer, reduces its affinity to water, and enhances its physical prop-erties. The aim of the present study was to evaluate the effect of a hydrophobic layer on the microleakage of class V composite restorations using different adhesives. Materials and methods The adhesives including total-etch Scotchbond MP and Single Bond, and the self-etch Clearfil SE Bond and Clearfil S3 Bond were applied to 80 class V cavities in vitro on the buccal surface in CEJ and then were fol-lowed by hydrophobic resin (Margin Bond) in half of the cavities in each group (n=10). After restoration with microhybrid composite, Z100 and immersion in fuchsine, the degree of microleakage was assessed. Data were analyzed using the Krus-kal-Wallis, Man-Whitney, and Wilcoxon tests. Results The hydrophobic layer significantly reduced the microleakage of Clearfil SE Bond and Clearfil S3 Bond only in dentin (p<0.05). There was no significant difference between enamel and dentinal margins in Clearfil S3 Bond, Clearfil SE Bond plus Margin Bond, and Clearfil S3 Bond plus Margin Bond (p>0.05). Conclusion Within the limitation of this study, only Clearfil S3 Bond could demonstrate the identical values of microle-akage in enamel and dentinal margins. PMID:23019500

  13. Improved interfacial adhesion in carbon fiber/polyether sulfone composites through an organic solvent-free polyamic acid sizing

    NASA Astrophysics Data System (ADS)

    Yuan, Haojie; Zhang, Shouchun; Lu, Chunxiang; He, Shuqing; An, Feng

    2013-08-01

    An organic solvent-free polyamic acid (PAA) nanoemulsion was obtained by direct ionization of the solid PAA in deionized water, with the average particle size of 261 nm and Zeta potential of -55.1 mV, and used as a carbon fiber sizing to improve the interfacial adhesion between the carbon fiber and polyether sulfone (PES). The surface characteristics of PAA coated carbon fibers were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and dynamic contact angle measurement. The results demonstrated that a continuous and uniform PAA sizing layer was formed on the surface of carbon fibers, and the surface energy of carbon fibers increased from 42.91 to 54.55 mN/m after sizing treatment. The single fiber pull-out testing was also performed, which showed the increased interfacial shear strength (IFSS) of carbon fiber/PES composites from 33.6 to 49.7 MPa by 47.9%. The major reasons for the improved interfacial adhesion were the increased van der Waals forces between the PES matrix and sizing layer as well as the chemical bonding between the sizing layer and carbon fiber surface. Furthermore, the PAA sizing also presented a positive effect on the interfacial adhesion of carbon fiber/PES composites under hydrothermal condition.

  14. Micro-tensile bond strength of different adhesive systems on sound dentin and resin-based composite: An in-vitro study

    PubMed Central

    Mallick, Rashmirekha; Sarangi, Priyanka; Mohanty, Sandhyarani; Behera, Subasish; Nanda, Soumyaranjan; Satapathy, Sukanta Kumar

    2015-01-01

    Aim: To analyze the difference in the micro-tensile bond strength of specimens made with two different adhesive systems and compare them with two homogenous substrates. Materials and Methods: Sixty permanent mandibular molars were mounted in acrylic blocks and sectioned with exposed dentin surfaces. Samples were then divided into four groups. To Group-I Adper Single Bond 2 and to Group-II Adper Self-Etch plus bonding agents were applied. For Group-I and Group-II beams consisted of resin composite in the upper half and dentin in the lower half. In Group-III beams were made of only dentin. In Group-IV beams were made of only composite. Fifteen specimens of each group were taken for the micro-tensile bond strength test. Statistical Analysis: The results are analyzed using one-way analysis of variance and Critical Difference test. Results: The interface bonded with the two adhesive systems had lower micro-tensile bond strength than those of dentin and resin composite and the self-etching adhesive Adper Self-Etch plus had comparable bond strength with total-etch adhesive Adper Single Bond 2. Conclusion: The bond strength values for current adhesive systems cannot be compared to the micro-tensile bond strength of dentin and resin composite, and self-etching adhesives have comparable bond strength with total-etch adhesives. PMID:26430301

  15. Micro-tensile bond strength of different adhesive systems on sound dentin and resin-based composite: An in-vitro study.

    PubMed

    Mallick, Rashmirekha; Sarangi, Priyanka; Mohanty, Sandhyarani; Behera, Subasish; Nanda, Soumyaranjan; Satapathy, Sukanta Kumar

    2015-01-01

    To analyze the difference in the micro-tensile bond strength of specimens made with two different adhesive systems and compare them with two homogenous substrates. Sixty permanent mandibular molars were mounted in acrylic blocks and sectioned with exposed dentin surfaces. Samples were then divided into four groups. To Group-I Adper Single Bond 2 and to Group-II Adper Self-Etch plus bonding agents were applied. For Group-I and Group-II beams consisted of resin composite in the upper half and dentin in the lower half. In Group-III beams were made of only dentin. In Group-IV beams were made of only composite. Fifteen specimens of each group were taken for the micro-tensile bond strength test. The results are analyzed using one-way analysis of variance and Critical Difference test. The interface bonded with the two adhesive systems had lower micro-tensile bond strength than those of dentin and resin composite and the self-etching adhesive Adper Self-Etch plus had comparable bond strength with total-etch adhesive Adper Single Bond 2. The bond strength values for current adhesive systems cannot be compared to the micro-tensile bond strength of dentin and resin composite, and self-etching adhesives have comparable bond strength with total-etch adhesives.

  16. Effect of adhesive luting on the fracture resistance of zirconia compared to that of composite resin and lithium disilicate glass ceramic

    PubMed Central

    Lim, Myung-Jin

    2017-01-01

    Objectives The purpose of this study was to evaluate the effect of adhesive luting on the fracture resistance of zirconia compared to that of a composite resin and a lithium disilicate glass ceramic. Materials and Methods The specimens (dimension: 2 mm × 2 mm × 25 mm) of the composite resin, lithium disilicate glass ceramic, and yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) were prepared. These were then divided into nine groups: three non-luting groups, three non-adhesive luting groups, and three adhesive luting groups, for each restorative material. In the non-luting groups, specimens were placed on the bovine tooth without any luting agents. In the non-adhesive luting groups, only zinc phosphate cement was used for luting the specimen to the bovine tooth. In the adhesive luting groups, specimens were pretreated, and the adhesive luting procedure was performed using a self-adhesive resin cement. For all the groups, a flexural test was performed using universal testing machine, in which the fracture resistance was measured by recording the force at which the specimen was fractured. Results The fracture resistance after adhesive luting increased by approximately 29% in the case of the composite resin, 26% in the case of the lithium disilicate glass ceramic, and only 2% in the case of Y-TZP as compared to non-adhesive luting. Conclusions The fracture resistance of Y-TZP did not increased significantly after adhesive luting as compared to that of the composite resin and the lithium disilicate glass ceramic. PMID:28194358

  17. Mechanical properties of adhesive systems at cryogenic and other temperatures

    NASA Technical Reports Server (NTRS)

    Staton, W. L.; Klich, P. J.; Cockrell, C. E.

    1982-01-01

    This paper presents a summary of the National Transonic Facility (NTF) fan blade adhesive characterization tests. Data was obtained at -300 F, room temperature (RT) and 200 F. The adhesive characterization data was acquired using specimens fabricated from materials orientated to simulate the lay up of the fan blades. Specimen fabrication, characterization tests, test equipment, test data, results and concluding remarks are reported. Adhesive test results are presented for specimens of the following types: lap shear, double lap shear, butt, short beam shear, flexure, and differential strain.

  18. Analytical and experimental study of the vibration of bonded beams with a lap joint

    NASA Technical Reports Server (NTRS)

    Rao, M. D.; Crocker, M. J.

    1990-01-01

    A theoretical model to study the flexural vibration of a bonded lap joint system is described in this paper. First, equations of motion at the joint region are derived using a differential element approach. The transverse displacements of the upper and lower beam are considered to be different. The adhesive is assumed to be linearly viscoelastic and the widely used Kelvin-Voight model is used to represent the viscoelastic behavior of the adhesive. The shear force at the interface between the adhesive and the beam is obtained from the simple bending motion equations of the two beams. The resulting equations of motion are combined with the equations of transverse vibration of the beams in the unjointed regions. These are later solved as a boundary value problem to obtain the eigenvalues and eigenvectors of the system. The model can be used to predict the natural frequencies, modal damping ratios, and mode shapes of the system for free vibration. Good agreement between numerical and experimental results was obtained for a system of graphite epoxy beams lap-jointed by an epoxy adhesive.

  19. Effect of different adhesives combined with two resin composite cements on shear bond strength to polymeric CAD/CAM materials.

    PubMed

    Bähr, Nora; Keul, Christine; Edelhoff, Daniel; Eichberger, Marlis; Roos, Malgorzata; Gernet, Wolfgang; Stawarczyk, Bogna

    2013-01-01

    This study tested the impact of different adhesives and resin composite cements on shear bond strength (SBS) to polymethyl methacrylate (PMMA)- and composite-based CAD/CAM materials. SBS specimens were fabricated and divided into five main groups (n=30/group) subject to conditioning: 1. Monobond Plus/Heliobond (MH), 2. Visio.link (VL), 3. Ambarino P60 (AM), 4. exp. VP connect (VP), and 5. no conditioning-control group (CG). All cemented specimens using a. Clearfil SA Cement and b. Variolink II were stored in distilled water for 24 h at 37 °C. Additionally, one half of the specimens were thermocycled for 5,000 cycles (5 °C/55 °C, dwell time 20 s). SBS was measured; data were analyzed using descriptive statistics, four- and one-way ANOVA, unpaired two-sample t-test and Chi(2)-test. CAD/CAM materials without additional adhesives showed no bond to resin composite cements. Highest SBS showed VL with Variolink II on composite-based material, before and after thermocycling.

  20. Laser ablation of enamel and composite using 355-nm laser pulses: influence of fluoride and laser treatment on adhesion

    NASA Astrophysics Data System (ADS)

    Larson, Michael D.; Gardner, Andrew K.; Staninec, Michal; Fried, Daniel

    2006-02-01

    Previous studies have demonstrated that Q-switched 355-nm laser pulses can be used to remove composite sealants and restorations from tooth surfaces without significant damage to sound tooth surfaces and have also shown that 355-nm lasers pulses can also be used to selectively etch the interprismatic protein of enamel to increase the effectiveness of topical fluoride for inhibiting decay and increase the bond strength to restorative materials without acid-etching. The first aim of this study was to test the hypothesis that topical fluoride can be applied after laser irradiation before composite resin placement without significantly reducing the bond-strength. The second aim was to test the hypothesis that thermal damage to existing composite due to laser irradiation does not compromise the adhesion of newly applied composite. There was a slight but significant reduction in the magnitude of the shear-bond strength of laser-treated surfaces with and without fluoride application. There was no significant difference in the magnitude of the bond strength between laser irradiated and non-laser irradiated aged composite to newly applied composite. These results suggest that after composite removal with 355-nm laser pulses fluoride can be subsequently applied to inhibit secondary caries before placement of composite restorative materials and that 355-nm laser pulses can be used for the repair of existing restorations.

  1. Adhesion improvement of electroless copper plating on phenolic resin matrix composite through a tin-free sensitization process

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Bian, Cheng; Jing, Xinli

    2013-04-01

    In order to improve the adhesion of electroless copper plating on phenolic resin matrix composite (PRMC), a new and efficient tin-free sensitization process has been developed. Electroless copper plating could be achieved in three steps, namely: (i) chemical etching with potassium permanganate solution; (ii) sensitization and activation with glucose and silver nitrate solution respectively; and (iii) electroless copper plating. Compared with the sample sensitized with stannous chloride (SnCl2), the copper plating obtained in the tin-free process showed excellent adhesion with the PRMC substrate, but had lower plating rate and conductivity. Additionally, the morphology of the copper plating was affected by the sensitization process, and the tin-free process was conducive to the formation of the large spherical copper polycrystal. Although the process is slightly complicated, the new sensitization process is so low-cost and environment-friendly that it is of great significance and could be applied into large-scale commercial manufacturing.

  2. Effect of Cigarette Smoke on Resin Composite Bond Strength to Enamel and Dentin Using Different Adhesive Systems.

    PubMed

    Theobaldo, J D; Catelan, A; Rodrigues-Filho, U; Marchi, G M; Lima, Danl; Aguiar, Fhb

    2016-01-01

    To evaluate the microshear bond strength of composite resin restorations in dental blocks with or without exposure to cigarette smoke. Eighty bovine dental blocks were divided into eight groups (n=10) according to the type of adhesive (Scotchbond Multi-Purpose, 3M ESPE, St Paul, MN, USA [SBMP]; Single Bond 2, 3M ESPE [SB]; Clearfil SE Bond, Kuraray Medical Inc, Okayama, Japan [CSEB]; Single Bond Universal, 3M ESPE [SBU]) and exposure to smoke (no exposure; exposure for five days/20 cigarettes per day). The adhesive systems were applied to the tooth structure, and the blocks received a composite restoration made using a matrix of perforated pasta. Data were statistically analyzed using analysis of variance and Tukey test (α<0.05). For enamel, there was no difference between the presence or absence of cigarette smoke (p=0.1397); however, there were differences among the adhesive systems (p<0.001). CSEB showed higher values and did not differ from SBU, but both were statistically different from SB. The SBMP showed intermediate values, while SB demonstrated lower values. For dentin, specimens subjected to cigarette smoke presented bond strength values that were lower when compared with those not exposed to smoke (p<0.001). For the groups without exposure to cigarette smoke, CSEB showed higher values, differing from SBMP. SB and SBU showed intermediary values. For the groups with exposure to cigarette smoke, SBU showed values that were higher and statistically different from SB and CSEB, which presented lower values of bond strength. SBMP demonstrated an intermediate value of bond strength. The exposure of dentin to cigarette smoke influenced the bonding strength of adhesives, but no differences were noted in enamel.

  3. Nucleation kinetics, growth and characterization of dLAP, dLAP:KF and dLAP:NaN 3 crystals

    NASA Astrophysics Data System (ADS)

    Hameed, A. S. Haja; Ravi, G.; Jayavel, R.; Ramasamy, P.

    2003-03-01

    The nucleation parameters, such as interfacial tension, radius of the critical nucleus and critical free energy change have been estimated for deuterated L-arginine phosphate (dLAP), potassium fluoride mixed dLAP and sodium azide mixed dLAP single crystals. Pure and additive mixed dLAP single crystals are grown by slow cooling technique. The effect of microbial contamination and colouration on the growth solutions has been studied. The crystalline powder of the grown crystals has been examined by X-ray diffraction and thermal analyses in order to estimate the lattice parameters and study thermal properties respectively.

  4. High Temperature Adhesives for Bonding Kapton

    NASA Technical Reports Server (NTRS)

    Stclair, A. K.; Slemp, W. S.; Stclair, T. L.

    1978-01-01

    Experimental polyimide resins were developed and evaluated as potential high temperature adhesives for bonding Kapton polyimide film. Lap shear strengths of Kapton/Kapton bonds were obtained as a function of test temperature, adherend thickness, and long term aging at 575K (575 F) in vacuum. Glass transition temperatures of the polyimide/Kapton bondlines were monitored by thermomechanical analysis.

  5. Dynamic fracture of adhesively bonded composite structures using cohesive zone models

    NASA Astrophysics Data System (ADS)

    Makhecha, Dhaval P.

    Using experimental data obtained from standard fracture test configurations, theoretical and numerical tools are developed to mathematically describe non-self-similar progression of cracks without specifying an initial crack. A cohesive-decohesive zone model, similar to the cohesive zone model known in the fracture mechanics literature as the Dugdale-Barenblatt model, is adopted to represent the degradation of the material ahead of the crack tip. This model unifies strength-based crack initiation and fracture-mechanics-based crack progression. The cohesive-decohesive zone model is implemented with an interfacial surface material that consists of an upper and a lower surface that are connected by a continuous distribution of normal and tangential nonlinear elastic springs that act to resist either Mode I opening, Mode II sliding, Mode III sliding, or a mixed anode. The initiation of fracture is determined by the interfacial strength and the progression of the crack is determined by the critical energy release rate. The adhesive is idealized with an interfacial surface material to predict interfacial fracture. The interfacial surface material is positioned within the bulk material to predict discrete cohesive cracks. The interfacial surface material is implemented through an interface element, which is incorporated in ABAQUS using the user defined element (UEL) option. A procedure is established to formulate a rate dependent model based on experiments carried out on compact tension test specimens. The rate dependent model is incorporated into the interface element approach to capture the unstable crack growth observed in experiments under quasi-static loading conditions. The compact tension test gives the variation of the fracture toughness with the rate of loading, this information is processed and a relationship between the fracture toughness and the rate of the opening displacement is established. The cohesive-decohesive zone model is implemented through a

  6. Effect of adhesive matrix composition and terpinolene on indomethacin bioavailability in rats from transdermal therapeutic system.

    PubMed

    Cal, Krzysztof; Sznitowska, Malgorzata; Janicki, Stanislaw

    2008-10-01

    Drug-in-adhesive matrix-type transdermal therapeutic systems for indomethacin (IND) were formulated and evaluated. Silicone and two types of polyacrylates were used as the bases of matrices. Terpinolene was used as a penetration enhancer. The physicochemical properties of matrices were determined. The bioavailability study of IND was performed in rats. The presence of IND in blood was demonstrated for each system. The calculated pharmacokinetics parameters for IND mainly depend on the solubility of IND in the adhesive layer. The positive influence of a penetration enhancer on IND bioavailability was observed only for one type of polyacrylate matrices.

  7. Rapid adhesive bonding and field repair of aerospace materials

    NASA Technical Reports Server (NTRS)

    Stein, B. A.

    1985-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process are often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid Adhesive Bonding concepts are developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens can be cut by a factor of 10 to 100 compared to standard press or autoclave bonding. The development of Rapid Adhesive Bonding for lap shear specimens (per ASTM D1002 and D3163), for aerospace panel or component bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric-matrix composite structures is reviewed. Equipment and procedures are described for bonding and repairing thin sheets, simple geometries, and honeycomb core panels.

  8. Large-scale Advanced Propfan (LAP) program

    NASA Technical Reports Server (NTRS)

    Sagerser, D. A.; Ludemann, S. G.

    1985-01-01

    The propfan is an advanced propeller concept which maintains the high efficiencies traditionally associated with conventional propellers at the higher aircraft cruise speeds associated with jet transports. The large-scale advanced propfan (LAP) program extends the research done on 2 ft diameter propfan models to a 9 ft diameter article. The program includes design, fabrication, and testing of both an eight bladed, 9 ft diameter propfan, designated SR-7L, and a 2 ft diameter aeroelastically scaled model, SR-7A. The LAP program is complemented by the propfan test assessment (PTA) program, which takes the large-scale propfan and mates it with a gas generator and gearbox to form a propfan propulsion system and then flight tests this system on the wing of a Gulfstream 2 testbed aircraft.

  9. Self-healing Nanofiber-Reinforced Polymer Composites. 2. Delamination/Debonding and Adhesive and Cohesive Properties.

    PubMed

    Lee, Min Wook; An, Seongpil; Jo, Hong Seok; Yoon, Sam S; Yarin, Alexander L

    2015-09-09

    The capacity for core-shell nanofiber mats containing healing agents (resin monomer and cure) in their cores to adhere to a substrate was studied using blister testing. After extended periodic bending, the adhesion energy was measured, and the effect of self-healing on the composite's delamination from the substrate was considered. In addition, the cohesion of two layers of the self-healing nanofibers was examined using blister testing and compared to that of ordinary nanofiber mats. The damage inflicted by prolonged periodic bending to the interface of the two nanofiber mats was demonstrated to have self-healed, and the cohesion energy was measured.

  10. Analysis of lap times in international swimming competitions.

    PubMed

    Robertson, Eileen; Pyne, David; Hopkins, Will; Anson, Judith

    2009-02-15

    Swimming performances were analysed for the top 16 finishers (semi-finalists, finalists) in nine international competitions over a 7-year period (1530 males, 1527 female). Total race time and intermediate lap times were log-transformed and analysed for effects of sex (male, female), stroke (freestyle, form strokes, individual medley), event (100, 200, and 400 m), and place (1-16). Between-athlete correlations characterized the relationship of each lap to final time, and within-athlete estimates quantified the effect of lap time on improvements in final time. Finalists exhibited very large correlations (r = 0.7-0.9) with final time in the second 50-m lap of 100-m events and the middle two 50-m and 100-m laps of 200-m and 400-m events respectively. For an individual swimmer, an achievable change in lap time was associated with an approximate 0.4-0.8% improvement in final time for finalists and an approximate 0.5-1.1% improvement in final time for semi-finalists, depending on sex, stroke, and event. The pattern of lap times was similar for the top 16 swimmers and between the best and worst swims for finalists. These findings indicate that substantial improvements can be made via the final lap in sprints and the middle two laps of 200- to 400-m events, but the overall pattern of lap times should not be changed.

  11. Inorganic composition and filler particles morphology of conventional and self-adhesive resin cements by SEM/EDX.

    PubMed

    Aguiar, Thaiane Rodrigues; Di Francescantonio, Marina; Bedran-Russo, Ana Karina; Giannini, Marcelo

    2012-10-01

    The purpose of this study was to characterize the inorganic components and morphology of filler particles of conventional and self-adhesive, dual-curing, resin luting cements. The main components were identified by energy dispersive X-ray spectroscopy microanalysis (EDX), and filler particles were morphologically analyzed by scanning electron microscopy (SEM). Four resin cements were used in this study: two conventional resin cements (RelyX ARC/3M ESPE and Clearfil Esthetic Cement/Kuraray Medical) and two self-adhesive resin cements (RelyX Unicem/3M ESPE and Clearfil SA Luting/Kuraray Medical). The materials (n = 5) were manipulated according to manufacturers' instructions, immersed in organic solvents to eliminate the organic phase and observed under SEM/EDX. Although EDX measurements showed high amount of silicon for all cements, differences in elemental composition of materials tested were identified. RelyX ARC showed spherical and irregular particles, whereas other cements presented only irregular filler shape. In general, self-adhesive cements contained higher filler size than conventional resin luting cements. The differences in inorganic components and filler particles were observed between categories of luting material and among them. All resin cements contain silicon, however, other components varied among them.

  12. Embedded optical fibres as strain sensors in polymer matrix fibre composites: The influence of adhesion in strain transfer

    NASA Astrophysics Data System (ADS)

    Ekroth, M.

    1994-06-01

    Optical fibers can serve as strain sensors embedded in load carrying polymer matrix fiber composites. The aim of the study was to investigate the influence of chemical bonding between the optical fiber, its protective polyimide coating and the surrounding composite, in strain transfer from the composite to the optical fiber. The degree of adhesion was determined by measuring the force during debonding and pull-out of the optical fiber from the composite. Debonding occurred between the quartz fiber and the coating for both untreated and ammonia modified fibers. The PTFE coated fibers debonded between the coating and the composite. The modified fibers debonded at a lower applied load than the untreated fibers. The strain during tensile loading was measured both with conventional resistance strain gages mounted on the specimen surfaces, and optically with a Mach-Zehnder-interferometer. The optically measured strains, obtained with the untreated fiber and the modified fibers, were all in good agreement with the response from the resistance strain gages. It is concluded that the chemical bonding between the quartz fiber/coating/composite consequently has little or no influence on the strain transfer. Internal stresses (mechanical pressure and friction forces) arising from the laminate fabrication process are sufficient for strain transfer.

  13. Marginal adaptation and fracture resistance of adhesively luted glass fibre-composite reinforced molar crowns with different inner crown surfaces.

    PubMed

    Behr, M; Rosentritt, M; Sikora, M I; Karl, P; Handel, G

    2003-09-01

    This study compared the influence of different inner crown surfaces on the fracture resistance and marginal adaptation of adhesively fixed glass fibre-reinforced molar crowns. Vectris/Targis crowns were constructed with an inner framework of glass fibres (directly on the tooth) or an inner veneering composite layer between the fibre-framework and the tooth-substance. Both groups were sandblasted inside using Al(2)O(3); 50 microm grain size (200 kPa, 20 s) and silane coated. A control group had the inner fibre framework, but was neither sandblasted nor silane coated. The crowns were adhesively cemented on extracted human teeth, and thermally cycled and mechanically loaded (TCML: 6000 x 5 degrees C/55 degrees C; 1.2 x 10(6) x 50 N, 1.66 Hz). The marginal adaptation before and after TCML was evaluated and the fracture resistance was investigated using a Zwick universal testing machine. After TCML the proportion of 'perfect margin' of the control group decreased significantly at the interface crown/cement. For the variations with an inner fibre framework or inner composite layer the marginal adaptation or fracture resistance did not decrease significantly after ageing. The fracture resistance values were control: 1509N+/-486; inner fibre framework: 1896N+/-342; inner composite layer: 1754N+/-340. In the case of the investigated fibre framework and veneering composite, the inner surface of glass fibre-reinforced molar crowns can be covered with a composite layer or with a glass fibre framework. Both methods achieve comparable high fracture strengths and reliable marginal adaptation.

  14. Quantitative analysis of aqueous phase composition of model dentin adhesives experiencing phase separation

    PubMed Central

    Ye, Qiang; Park, Jonggu; Parthasarathy, Ranganathan; Pamatmat, Francis; Misra, Anil; Laurence, Jennifer S.; Marangos, Orestes; Spencer, Paulette

    2013-01-01

    There have been reports of the sensitivity of our current dentin adhesives to excess moisture, for example, water-blisters in adhesives placed on over-wet surfaces, and phase separation with concomitant limited infiltration of the critical dimethacrylate component into the demineralized dentin matrix. To determine quantitatively the hydrophobic/hydrophilic components in the aqueous phase when exposed to over-wet environments, model adhesives were mixed with 16, 33, and 50 wt % water to yield well-separated phases. Based upon high-performance liquid chromatography coupled with photodiode array detection, it was found that the amounts of hydrophobic BisGMA and hydrophobic initiators are less than 0.1 wt % in the aqueous phase. The amount of these compounds decreased with an increase in the initial water content. The major components of the aqueous phase were hydroxyethyl methacrylate (HEMA) and water, and the HEMA content ranged from 18.3 to 14.7 wt %. Different BisGMA homologues and the relative content of these homologues in the aqueous phase have been identified; however, the amount of crosslinkable BisGMA was minimal and, thus, could not help in the formation of a crosslinked polymer network in the aqueous phase. Without the protection afforded by a strong crosslinked network, the poorly photoreactive compounds of this aqueous phase could be leached easily. These results suggest that adhesive formulations should be designed to include hydrophilic multimethacrylate monomers and water compatible initiators. PMID:22331596

  15. Effect of different adhesive strategies on the post-operative sensitivity of class I composite restorations.

    PubMed

    Sancakli, Hande Sar; Yildiz, Esra; Bayrak, Isil; Ozel, Sevda

    2014-01-01

    To evaluate the post-operative sensitivity of occlusal restorations using different dentin adhesives performed by an undergraduate and a post-doctorate dentist. One hundred and eighty-eight molar occlusal restorations were placed in 39 patients (ages between 18 and 30) using 3 different kind of adhesive systems; Optibond FL (OBF), Clearfil Protect Bond (CPB), and iBond (IB) by a post-doctorate dentist or a fifth-year dental student according to the manufacturers' instructions. Post-operative sensitivity to cold and air was evaluated using a Visual Analog Scale (VAS) after 24 hours, 30, 90, and 180 days. Data were analyzed using the Mann-Whitney U and Friedman tests (P < 0.05). Post-operative sensitivity scores for OBF and CPB were higher for the dental student (P < 0.05), while IB scores did not differ statistical significantly according to the operator (P > 0.05). Operator skill and experience appears to play a role in determining the outcome of post-operative sensitivity of multi-step adhesive systems although the post-operative sensitivity was low. It is suggested that the less experienced clinicians (rather than experienced clinicians) should better use the self-etching dentin bonding systems with reduced application steps to minimize the potential risk of post-operative sensitivity of dental adhesives.

  16. Effect of different adhesive strategies on the post-operative sensitivity of class I composite restorations

    PubMed Central

    Sancakli, Hande Sar; Yildiz, Esra; Bayrak, Isil; Ozel, Sevda

    2014-01-01

    Objective: To evaluate the post-operative sensitivity of occlusal restorations using different dentin adhesives performed by an undergraduate and a post-doctorate dentist. Materials and Methods: One hundred and eighty-eight molar occlusal restorations were placed in 39 patients (ages between 18 and 30) using 3 different kind of adhesive systems; Optibond FL (OBF), Clearfil Protect Bond (CPB), and iBond (IB) by a post-doctorate dentist or a fifth-year dental student according to the manufacturers’ instructions. Post-operative sensitivity to cold and air was evaluated using a Visual Analog Scale (VAS) after 24 hours, 30, 90, and 180 days. Data were analyzed using the Mann-Whitney U and Friedman tests (P < 0.05). Results: Post-operative sensitivity scores for OBF and CPB were higher for the dental student (P < 0.05), while IB scores did not differ statistical significantly according to the operator (P > 0.05). Conclusion: Operator skill and experience appears to play a role in determining the outcome of post-operative sensitivity of multi-step adhesive systems although the post-operative sensitivity was low. It is suggested that the less experienced clinicians (rather than experienced clinicians) should better use the self-etching dentin bonding systems with reduced application steps to minimize the potential risk of post-operative sensitivity of dental adhesives. PMID:24966741

  17. Spider's super-glue: thread anchors are composite adhesives with synergistic hierarchical organization.

    PubMed

    Wolff, Jonas O; Grawe, Ingo; Wirth, Marina; Karstedt, André; Gorb, Stanislav N

    2015-03-28

    Silk is a key innovation in spiders, fascinating both biologists and material scientists. However, to fulfil their biological function silken threads must be strongly fastened to substrates or other threads. The majority of modern spiders produce a unique and rather unexplored bio-adhesive: the two-compound pyriform secretion, which is spun into elaborate patterns (so called attachment discs) and used to anchor silken threads to substrates. Strong adhesion is achieved on a high variety of surfaces with a minimum of mate