Science.gov

Sample records for copolymer thermoplastic vulcanizates

  1. Thermoplastic vulcanizates: new materials of choice.

    PubMed

    Severyns, K

    2000-03-01

    Increasingly, thermoplastic vulcanizates of ethylene propylene diene monomer rubber-polypropylene are being specified for medical applications. This article describes their properties and advantages over thermoset rubbers and other conventional medical elastomeric materials.

  2. Preparation of polypropylene (PP)/ethylene octene copolymer (EOC) thermoplastic vulcanizates (TPVs) by high energy electron reactive processing

    NASA Astrophysics Data System (ADS)

    Rajeshbabu, R.; Gohs, U.; Naskar, K.; Thakur, V.; Wagenknecht, U.; Heinrich, G.

    2011-12-01

    Thermoplastic vulcanizates (TPVs) based on 50/50 composition of PP/EOC blend were prepared by electron induced reactive processing. To facilitate dynamic crosslinking in the PP/EOC blend, a 1.5 MeV electron accelerator was directly coupled to an internal mixer to induce chemical reactions via high energy electrons under dynamic conditions of melt mixing process. This kind of setup has been conceptualized for the first time in our laboratory and termed as electron induced reactive processing (EIReP) technique. Mechanical, morphological, and rheological properties of PP/EOC TPVs were studied with special reference to the exposure time (16-64 s) keeping absorbed dose (100 kGy) and electron energy (1.5 MeV) invariable. Chain scission dominates over chain crosslinking in both EOC as well as PP phases with the increase in exposure time. The primary factor is found to be the predominance of oxidative degradation during electron induced reactive processing in air atmosphere. The above observation was supported by Fourier Transform Infrared analyses and gel content values. Furthermore, it was found that mechanical properties depend not only on the extent of degradation in the blend system but also on the state and the mode of dispersion of the blend components.

  3. Investigation the degradation and devulcanization reaction of thermoplastic vulcanizate using peroxide compound

    NASA Astrophysics Data System (ADS)

    Temram, Chokkanit; Wattanakul, Karnthidaporn

    2012-09-01

    Investigation the Degradation and Devulcanization Reaction of Thermoplastic Vulcanizate using Peroxide Compound was carried out by means of benzoyl peroxide as a devulcanizing agent. The temperature for the recycling condition was gradually increased from 80°C to 190°C because of the half-life of benzoyl peroxide. Furthermore, the effects of time and concentration of devulcanizing agent on the recycling process were investigated. The extent of devulcanization of thermoplastic vulcanizate was studied by estimation of percent devulcanization, gel fraction of rubber after swelling and crosslink density. According to the results, we found that the crosslink density of devulcanized thermoplastic vulcanizate was 29.37% less than virgin thermoplastic vulcanizate by adding benzoyl peroxide for 1 phr. This result is correspondence to the decreasing in gel fraction of devulcanized thermoplastic vulcanizate. Moreover, the addition of 5 phr and 10 phr to TPVs result to the significant decrement in crosslink density about 64%. The effect of temperature for devulcanization was also investigated to obtain the optimum conditions. The result shows that the percentage of devulcanization was slightly increased as the increasing in the starting temperature from 80°C to 105°C.

  4. Fly ash reinforced thermoplastic vulcanizates obtained from waste tire powder.

    PubMed

    Sridhar, V; Xiu, Zhang Zhen; Xu, Deng; Lee, Sung Hyo; Kim, Jin Kuk; Kang, Dong Jin; Bang, Dae-Suk

    2009-03-01

    Novel thermoplastic composites made from two major industrial and consumer wastes, fly ash and waste tire powder, have been developed. The effect of increasing fly ash loadings on performance characteristics such as tensile strength, thermal, dynamic mechanical and magnetic properties has been investigated. The morphology of the blends shows that fly ash particles have more affinity and adhesion towards the rubbery phase when compared to the plastic phase. The fracture surface of the composites shows extensive debonding of fly ash particles. Thermal analysis of the composites shows a progressive increase in activation energy with increase in fly ash loadings. Additionally, morphological studies of the ash residue after 90% thermal degradation shows extensive changes occurring in both the polymer and filler phases. The processing ability of the thermoplastics has been carried out in a Monsanto processability testing machine as a function of shear rate and temperature. Shear thinning behavior, typical of particulate polymer systems, has been observed irrespective of the testing temperatures. Magnetic properties and percolation behavior of the composites have also been evaluated.

  5. Characterization the effect of disulfide compound on the devulcanization of thermoplastic vulcanizate

    NASA Astrophysics Data System (ADS)

    Rodsuk, Sikarin; Ritsuar, Suphattarachai; Wattanakul, Karnthidaporn

    2012-09-01

    The use of disulfides and the application of mechanical force in rubber devulcanization have been reported in the literatures. In this work, the devulcanization of thermoplastic vulcanizate (TPVs) which is polypropylene/ethylene propylene diene rubber blend, is conducted in a Brabender batch mixer using diphenyl disulfide as the devulcanizing agent. Considering the complexity of the compound, the effect of devulcanizing agent concentration, temperature and time were investigated to obtain the optimum condition. The extent of devulcanization of thermoplastic vulcanizate was studied by determination the volume fraction of dried rubber after swelling and crosslink density. The result show that the crosslink density of devulcanized TPVs decreased to 60.33% and 68.24% for 1 phr and 5 phr, respectively, and significantly decreased to 68.94% by adding 10 phr of diphenyl disulfide at 190°C. Moreover, the percent devulcanization of TPVs increased from 68.24% to 72.12% with increased in the reaction temperature up to 230 °C.

  6. Finite element analysis as a design tool for thermoplastic vulcanizate glazing seals

    SciTech Connect

    Gase, K.M.; Hudacek, L.L.; Pesevski, G.T.

    1998-12-31

    There are three materials that are commonly used in commercial glazing seals: EPDM, silicone and thermoplastic vulcanizates (TPVs). TPVs are a high performance class of thermoplastic elastomers (TPEs), where TPEs have elastomeric properties with thermoplastic processability. TPVs have emerged as materials well suited for use in glazing seals due to ease of processing, economics and part design flexibility. The part design and development process is critical to ensure that the chosen TPV provides economics, quality and function in demanding environments. In the design and development process, there is great value in utilizing dual durometer systems to capitalize on the benefits of soft and rigid materials. Computer-aided design tools, such as Finite Element Analysis (FEA), are effective in minimizing development time and predicting system performance. Examples of TPV glazing seals will illustrate the benefits of utilizing FEA to take full advantage of the material characteristics, which results in functional performance and quality while reducing development iterations. FEA will be performed on two glazing seal profiles to confirm optimum geometry.

  7. Influence of different crosslinking systems on the mechanical and morphological properties of thermoplastic vulcanizates

    NASA Astrophysics Data System (ADS)

    Patermann, Simone; Altstädt, Volker

    2015-05-01

    Thermoplastic vulcanizates (TPVs) combine the elastic properties of thermoset cross-linked rubbers with the melt processability of thermoplastics. The most representative examples of this class are the TPVs based on polypropylene (PP) and ethylene-propylene-diene terpolymer rubber (EPDM). The PP/EPDM blends were produced by dynamic vulcanization in a continuous extrusion process. The influence of different crosslinking systems was studied with regard to cross-link density, compression set, tensile strength/elongation at break and morphology. With increasing peroxide concentration, the cross-link density increases, leading to a reduction of the compression set by 50 %. The same improvement is only reachable with twice the concentration of phenolic resin. Only the peroxide cross-linked blends show smaller dispersed EPDM particles with increasing peroxide concentration. With a peroxide concentration between 0.2 and 0.5 wt. %, a maximum in tensile strength and elongation at break was found. For the phenolic resin cross-linked blends, the tensile strength stays almost constant with increasing phenolic resin concentration and the elongation at break shows best results at 0.5 wt. % phenolic resin. Compared to batch processes, the results show different values, but comparable trends.

  8. Study of friction and wear of thermoplastic vulcanizates: the correlation with abraded surfaces topology

    NASA Astrophysics Data System (ADS)

    Harea, E.; Stoček, R.; Machovský, M.

    2017-05-01

    The work was focused on the study of friction and wear properties of thermoplastic vulcanizates (TPV) based on polypropylene (PP), natural rubber (NR) and styrene butadiene rubber (SBR) compounds containing all common additives and curatives using ball-on-flat method. Pure materials and binary TPV blends of PP/NR, as well those of PP/SBR with the compositions 95/5, 75/25 and 50/50 (in weight %) were compounded and analysed. It is very well known that the coefficient of friction (COF), as well as wear values of pure thermoplastic matrix are significantly lower than those for pure rubber. Thus, it was found that the friction coefficient and wear of TPVs significantly increased in accordance with increased content of rubber material. Surprisingly, NR compared with SBR of similar concentrations in PP matrix, considerably affected wear of samples and the friction coefficient remained almost unaffected. Finally the topology of abraded surfaces were examined by using scanning electron microscopy (SEM) in order to understand the relationship between the COF, wear process and the composition of TPVs.

  9. New understanding of microstructure formation of the rubber phase in thermoplastic vulcanizates (TPV).

    PubMed

    Wu, Hanguang; Tian, Ming; Zhang, Liqun; Tian, Hongchi; Wu, Youping; Ning, Nanying

    2014-03-21

    The breakup of the rubber phase in an ethylene-propylene-diene monomer (EPDM)/polypropylene (PP) blend at the early stage of dynamic vulcanization is similar to that in an unvulcanized EPDM/PP blend because of the low crosslink density of the EPDM phase. In this work, the minimum size of the rubber phase in the unvulcanized EPDM/PP blend was first calculated by using the critical breakup law of viscoelastic droplets in a matrix. The calculated results showed that the minimum size of the rubber phase in the unvulcanized blend was in the nanometer scale (25-46 nm), not the micrometer scale as reported in many works. Meanwhile, the actual size of the rubber phase in the thermoplastic vulcanizate (TPV) at both the early stage and the final stage of dynamic vulcanization was observed by using peak force tapping atomic force microscopy (PF-AFM). The results indicated that the EPDM phase indeed broke up into nanoparticles at the early stage of dynamic vulcanization, in good agreement with the calculated results. More interestingly, we first revealed that the micrometer-sized rubber particles commonly observed in TPV were actually the agglomerates of rubber nanoparticles with diameters between 40 and 60 nm. The mechanism for the formation of rubber nanoparticles and their agglomerates during dynamic vulcanization was then discussed. Our work provides guidance to control the microstructure of the rubber phase in TPV to prepare high performance TPV products for a wide range of applications in the automobile and electronic industries.

  10. Fully biobased and supertough polylactide-based thermoplastic vulcanizates fabricated by peroxide-induced dynamic vulcanization and interfacial compatibilization.

    PubMed

    Liu, Guang-Chen; He, Yi-Song; Zeng, Jian-Bing; Li, Qiu-Tong; Wang, Yu-Zhong

    2014-11-10

    A fully biobased and supertough thermoplastic vulcanizate (TPV) consisting of polylactide (PLA) and a biobased vulcanized unsaturated aliphatic polyester elastomer (UPE) was fabricated via peroxide-induced dynamic vulcanization. Interfacial compatibilization between PLA and UPE took place during dynamic vulcanization, which was confirmed by gel measurement and NMR analysis. After vulcanization, the TPV exhibited a quasi cocontinuous morphology with vulcanized UPE compactly dispersed in PLA matrix, which was different from the pristine PLA/UPE blend, exhibiting typically phase-separated morphology with unvulcanized UPE droplets discretely dispersed in matrix. The TPV showed significantly improved tensile and impact toughness with values up to about 99.3 MJ/m(3) and 586.6 J/m, respectively, compared to those of 3.2 MJ/m(3) and 16.8 J/m for neat PLA, respectively. The toughening mechanisms under tensile and impact tests were investigated and deduced as massive shear yielding of the PLA matrix triggered by internal cavitation of VUPE. The fully biobased supertough PLA vulcanizate could serve as a promising alternative to traditional commodity plastics.

  11. Tough and Sustainable Graft Block Copolymer Thermoplastics

    SciTech Connect

    Zhang, Jiuyang; Li, Tuoqi; Mannion, Alexander M.; Schneiderman, Deborah K.; Hillmyer, Marc A.; Bates, Frank S.

    2016-03-15

    Fully sustainable poly[HPMC-g-(PMVL-b-PLLA)] graft block copolymer thermoplastics were prepared from hydroxypropyl methylcellulose (HPMC), β-methyl-δ-valerolactone (MVL), and l-lactide (LLA) using a facile two-step sequential addition approach. In these materials, rubbery PMVL functions as a bridge between the semirigid HPMC backbone and the hard PLLA end blocks. This specific arrangement facilitates PLLA crystallization, which induces microphase separation and physical cross-linking. By changing the backbone molar mass or side chain composition, these thermoplastic materials can be easily tailored to access either plastic or elastomeric behavior. Moreover, the graft block architecture can be utilized to overcome the processing limitations inherent to linear block polymers. Good control over molar mass and composition enables the deliberate design of HPMC-g-(PMVL-b-PLLA) samples that are incapable of microphase separation in the melt state. These materials are characterized by relatively low zero shear viscosities in the melt state, an indication of easy processability. The simple and scalable synthetic procedure, use of inexpensive and renewable precursors, and exceptional rheological and mechanical properties make HPMC-g-(PMVL-b-PLLA) polymers attractive for a broad range of applications.

  12. Thermoplastic vulcanizate nanocomposites based on polypropylene/ethylene propylene diene terpolymer (PP/EPDM) prepared by reactive extrusion

    NASA Astrophysics Data System (ADS)

    Mirzadeh, Amin

    For this work, different grades of polypropylene-g-maleic anhydride polymers were chosen to elucidate the effect of compatibilizer on the nanoclay dispersion level in thermoplastic phase. X-ray diffraction (XRD) patterns along with transmission electron microscopy (TEM) and scanning electron microscope (SEM) micrographs confirmed that prepared PP nanocomposites ranged from intercalated structure to a coexistence of intercalated tactoids and exfoliated layers namely “partially exfoliated” nanocomposite. Among various factors affecting the compatibilizer performance, it is shown that only the relaxation behaviour of compatibilizer correlates directly with the nanocomposites characterization results; higher relaxation times of the compatibilizer are associated with better dispersion of nanoclay. To study the co-continuity development of the nonreactive blends, EPDM and the mentioned PP nanocomposites at various compositions were melt blended using an internal mixer. Based on continuity measurements of TPEs and TPE nanocomposites for both thermoplastic and rubber phase, it is shown that the presence of nanoclay decreases the co-continuity composition range and alters its symmetrical feature. However, this effect is more pronounced in the intercalated nanocomposites than in partially exfoliated nanocomposites. It seems that better nanoclay dispersion limits the reduction of the thermoplastic phase continuity in a manner that the continuity index of the thermoplastic phase for partially exfoliated TPE nanocomposite prepared at high EPDM content (i.e. at 70 wt%) is greater than that of corresponding TPE without nanoclay. According to these results, it is possible to shift to higher EPDM content using partially exfoliated system before formation of matrix-dispersed particle structure which limits thermoplastic vulcanizate production. This should be mentioned that gamma irradiation was carried out in order to fix the EPDM morphology to estimate the continuity of PP

  13. Polypropylene/natural rubber thermoplastic vulcanizates by eco-friendly and sustainable electron induced reactive processing

    NASA Astrophysics Data System (ADS)

    Mondal, Manas; Gohs, Uwe; Wagenknecht, Udo; Heinrich, Gert

    2013-07-01

    TPVs are a special class of thermoplastic and elastomer blend where cross-linking of elastomeric phase takes place during melt mixing process known as dynamic vulcanization (DV). A 50/50 blend of natural rubber (NR) and polypropylene (PP) were dynamically vulcanized using Electron Induced Reactive Processing (EIReP) as a function of absorbed dose (150, 250, and 350 kGy) at fixed electron energy (1.5 MeV) and dose per rotation. Different methods like tensile test, DSC, melt rheology, and SEM have been employed to understand the structure-property relationship of the prepared samples. The results suggest that EIReP is a novel technique to offer handful of additional features without compromising the end user property.

  14. Deformation mechanisms of sub-micrometer thermoplastic vulcanizates obtained by reaction-induced phase separation of miscible poly(ε-caprolactone)/dimethacrylate systems.

    PubMed

    l'Abee, Roy; van Duin, Martin; Goossens, Han

    2017-08-24

    The micromechanical deformation mechanisms of sub-μm thermoplastic vulcanizates (TPVs) based on poly(ε-caprolactone) (PCL) and cross-linked methacrylate rubbers were studied by time-resolved small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) measurements in order to better understand the underlying deformation mechanisms responsible for the high elongation at break and good elastic recovery of sub-μm TPVs. It is demonstrated that, in contrast to neat PCL, the interlamellar void formation in the PCL matrix and subsequent coalescence of voids is suppressed by the presence of the rubber (nano)particles in these TPVs. The deformation of the TPVs under tensile conditions is dominated by yielding of the PCL matrix, which is initially localized at the equatorial regions of the rubber particles and progresses towards the polar regions at higher strains. Re-ordering of the crystal structures is both time and stress dependent, and stress relaxation of the TPV under tension is primarily governed by the break-up of the crystal lamellae at the equatorial regions of the rubber particles. This study demonstrates that the rubber particle size as well as chemical grafting of thermoplastic polymer chains onto the surface of cross-linked rubber particles are important parameters to control the mechanical deformation behavior of TPVs.

  15. In situ reactive compatibilization of polypropylene/ethylene-propylene-diene monomer thermoplastic vulcanizate by zinc dimethacrylate via peroxide-induced dynamic vulcanization.

    PubMed

    Chen, Yukun; Xu, Chuanhui; Liang, Xingquan; Cao, Liming

    2013-09-12

    This work demonstrates an approach of in situ reactive compatibilization between polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) by using zinc dimethacrylate (ZDMA) as a compatibilizer and, simultaneously, as a very strong reinforcing agent. With the incorporation of 7phr ZDMA in the PP/EPDM (30/70, w/w) thermoplastic vulcanizate (TPV), the tensile strength, tear strength, elongation at break, and hardness of PP/EPDM/ZDMA TPV were increased from 5.3 MPa, 31.3 kN/m, 222%, and 78 up to 11.2 MPa, 64.2 kN/m, 396%, and 83, respectively. This tremendous reinforcing as well as the compatibilization effect of the ZDMA was understood by polymerization of ZDMA and ZDMA reacted with EPDM and PP during peroxide-induced dynamic vulcanization. A peculiar phase structure that rubber particles were surrounded and "bonded" by a thick transition zone that contained numerous of nanoparticles with dimensions of about 20-30 nm was observed from transmission electron microscopy. Scanning electron microscopy results confirmed that incorporation of ZDMA reduced the size of the cross-linked EPDM particles. Moreover, we found that the compatibilized TPV showed a higher tan δ peak temperature for EPDM phase and a lower tan δ peak temperature for PP phase. The suggested method for in situ reactive compatibilization of PP and EPDM offers routes to the design of new TPV-based technical products for diversified applications.

  16. Supertoughened Biobased Poly(lactic acid)-Epoxidized Natural Rubber Thermoplastic Vulcanizates: Fabrication, Co-continuous Phase Structure, Interfacial in Situ Compatibilization, and Toughening Mechanism.

    PubMed

    Wang, Youhong; Chen, Kunling; Xu, Chuanhui; Chen, Yukun

    2015-09-10

    In the presence of dicumyl peroxide (DCP), biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization. Interfacial in situ compatibilization between PLA and ENR phases was confirmed by Fourier transform infrared spectroscopy (FT-IR). A novel "sea-sea" co-continuous phase in the PLA/ENR TPVs was observed through scanning electron microscopy (SEM) and differed from the typical "sea-island" morphology that cross-linked rubber particles dispersed in plastic matrix. A sharp, brittle-ductile transition occurred with 40 wt % of ENR, showing a significantly improved impact strength of 47 kJ/m(2), nearly 15 times that of the neat PLA and 2.6 times that of the simple blend with the same PLA/ENR ratio. Gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) results suggested that a certain amount of DCP was consumed in the PLA phase, causing a slight cross-linking or branching of PLA molecules. the effects of various DCP contents on the impact property were investigated. The toughening mechanism under impact testing was researched, and the influence factors for toughening were discussed.

  17. Recent Developments on Thermoplastic Elastomers by Dynamic Vulcanization

    NASA Astrophysics Data System (ADS)

    Babu, R. Rajesh; Naskar, Kinsuk

    A comprehensive overview is given of the recent developments of thermoplastic vulcanizates (TPVs) with special reference to the technological advancements. TPVs combine the high volume molding capability of thermoplastics with the elastomeric properties of thermoset rubber. Therefore, they lend themselves to a broad range of applications in various fields. TPVs represent the second largest group of soft thermoplastic elastomers, after styrenic-based block copolymers. TPVs have undergone evolutionary changes in terms of the selection of polymers, design of crosslinking, compounding techniques, and methods of production, and have achieved better elastic recovery, easy processability and low hardness etc.

  18. Lignin-derived thermoplastic co-polymers and methods of preparation

    DOEpatents

    Naskar, Amit K.; Saito, Tomonori; Pickel, Joseph M.; Baker, Frederick S.; Eberle, Claude Clifford; Norris, Robert E.; Mielenz, Jonathan Richard

    2014-06-10

    The present invention relates to a crosslinked lignin comprising a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, wherein said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100.degree. C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. Thermoplastic copolymers containing the crosslinked lignin are also described. Methods for producing the crosslinked lignin and thermoplastic copolymers are also described.

  19. Thermoplastic rubber comprising ethylene-vinyl acetate copolymer, asphalt and fluxing oil

    NASA Technical Reports Server (NTRS)

    Hendel, F. J. (Inventor)

    1970-01-01

    A thermoplastic rubber is made from a mixture of between about 10 percent and about 50 percent of asphalt, between about 5 percent and about 30 percent fluxing oil, and between about 35 percent and about 70 percent of a copolymer of polyethylene and vinyl acetate.

  20. Toward Strong Thermoplastic Elastomers with Asymmetric Miktoarm Block Copolymer Architectures

    DTIC Science & Technology

    2014-03-05

    plastic -to- rubber ” transition and can lead to higher recovery of the total strain (Figure S3 in Supporting Information).25 The miktoarm S(IS′)3...and elastic materials. A straightforward and very promising future direction consists in blending the miktoarm block copolymers with a second polymer...SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 See Attached

  1. Thermoplastic Adhesives based on polyolefin and olefinic copolymers

    NASA Astrophysics Data System (ADS)

    Paul, Rituparna

    2014-03-01

    H.B. Fuller has been a leading global industrial adhesive manufacturer for over 125 years. It is a company with a rich history of consistently delivering adhesive innovations for enhancing product performance in the market place. H.B. Fuller technologies/products find application in several markets including packaging, personal hygiene and nonwovens, durable assembly and electronics. In this presentation, H. B. Fuller's technology innovation journey will be shared with emphasis on groundbreaking technologies/products based on polyolefin and olefin copolymers.

  2. Thermoplastic Dielectric Elastomer of Triblock Copolymer with High Electromechanical Performance.

    PubMed

    Ma, Zipeng; Xie, Yuhan; Mao, Jie; Yang, Xuxu; Li, Tiefeng; Luo, Yingwu

    2017-08-01

    Dielectric elastomer (DE) actuators have been shown to have promising applications as soft electromechanical transducers in many emerging technologies. The DE actuators, which are capable of large actuation strain over a wide range of excitation frequencies, are highly desirable. Here, the first single-component DE of a triblock copolymer with attractive electromechanical performance is reported. Symmetric poly(styrene-b-butyl acrylate-b-styrene) (SBAS) is designed and synthesized. The SBAS actuator exhibits about 100% static actuation area strain and excellent dynamic performance, as evidenced by a wide half bandwidth of 300 Hz and a very high specific power of 1.2 W g(-1) within the excitation frequency range of 300-800 Hz. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Injection molding of thermoplastic elastomers for microstructured substrates

    NASA Astrophysics Data System (ADS)

    Birkar, Smita

    Amorphous and semi-crystalline thermoplastic polymers have been widely investigated for injection molding of parts with microstructured surfaces. Microstructured surfaces injection molded from thermoplastic elastomers have emerging applications as superhydrobic surfaces and patterned adhesives, but there is a limited understanding of the factors affecting replication with these materials. This research was a continued investigation of block copolymer thermoplastic elastomers as well as the first in-depth examination of thermoplastic vulcanizates for injection molding microfeatures. The first focus of this research was the interactions between tooling aspect ratio and feature orientation (negative and positive tooling) and thermoplastic elastomer hard segment content on microfeature replication. Electroformed nickel tooling having positive and negative features with different geometries and aspect ratios of 0.02:1 to 2:1 were molded from three copolyester thermoplastic elastomers with similar chemistry and different hardness values. The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Results were correlated with elastomer properties. In the second parts of this research, the effects of microfeature spacing on the replication of thermoplastic elastomer features was investigated using micropillars with two diameters (10 and 20 mum) and three spacing ratios (0.5:1, 1:1, and 2:1). The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Feature spacing significantly affected the replication of micropillars using a thermoplastic elastomer. This replication was competition between cooling and pressurization of the melt. Wider spacing between smaller features allowed cooling in the tooling lands to dominate the feature filling. Higher pressures did

  4. New blends of ethylene-butyl acrylate copolymers with thermoplastic starch. Characterization and bacterial biodegradation.

    PubMed

    Morro, A; Catalina, F; Corrales, T; Pablos, J L; Marin, I; Abrusci, C

    2016-09-20

    Ethylene-butyl acrylate copolymer (EBA) with 13% of butyl acrylate content was used to produce blends with 10, 30 and 60% of thermoplastic starch (TPS) plasticized with glycerol. Ethylene-acrylic acid copolymer (EAA) was used as compatibilizer at 20% content with respect to EBA. The blends were characterized by X-ray diffraction, ATR-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), water-Contact Angle measurements (CA), Differential Scanning Calorimetry (DSC) and Stress-strain mechanical tests. Initiated autoxidation of the polymer blends was studied by chemiluminescence (CL) confirming that the presence of the polyolefin-TPS interphase did not substantially affect the oxidative thermostability of the materials. Three bacterial species have been isolated from the blend films buried in soil and identified as Bacillus subtilis, Bacillus borstelensis and Bacillus licheniformis. Biodegradation of the blends (28days at 45°C) was evaluated by carbon dioxide measurement using the indirect impedance technique. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Compatible blends of thermoplastic starch and hydrolyzed ethylene-vinyl acetate copolymers.

    PubMed

    Da Róz, A L; Ferreira, A M; Yamaji, F M; Carvalho, A J F

    2012-09-01

    Ethylene-vinyl acetate copolymer (EVA) with 19% of vinyl acetate and its derivatives modified by hydrolysis of 50 and 100% of the initial vinyl acetate groups were used to produce blends with thermoplastic starch (TPS) plasticized with 30 wt% glycerol. The blends were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, water absorption, stress-strain mechanical tests, dynamic mechanical analysis and thermogravimetric analysis. In contrast to the blends with unmodified EVA, those made with hydrolyzed EVA were compatible, as demonstrated by the brittle fracture surface analysis and the results of thermal and mechanical tests. The mechanical characteristics and water absorption of the TPS were improved even with a small addition (2.5 wt%) of hydrolyzed EVA. The glass transition temperature rose with the degree of hydrolysis of EVA by 40 and 50°, for the EVA with 50 and 100% hydrolysis, respectively. The addition of hydrolyzed EVA proved to be an interesting approach to improving TPS properties, even when very small quantities were used, such as 2.5 wt%.

  6. Thermoplastic biodegradable elastomers based on ε-caprolactone and L-lactide block co-polymers: a new synthetic approach.

    PubMed

    Lipik, Vitali T; Kong, Jen Fong; Chattopadhyay, Sujay; Widjaja, Leonardus K; Liow, Sing S; Venkatraman, Subbu S; Abadie, Marc J M

    2010-11-01

    Although biodegradable polymers have found extensive application in medical devices, there are very few commercially available elastomeric biodegradable polymers. In this work, starting with the well-known monomers L-lactide and ε-caprolactone, we developed elastomers using a multiblock co-polymer approach. This ensures that the degradation products of such elastomers are also acceptable from a cytotoxicity standpoint. A series of polymers with various structures was synthesized utilizing a design of experiment approach. The basic structure is that of a diblock, with each block being modified by the addition of co-monomer. The synthesized polymers exhibited a range of mechanical properties from a typical thermoplastic polymer to that approaching a good thermoplastic elastomer. 13C nuclear magnetic resonance analysis, size exclusion chromatography and differential scanning calorimetry measurements have been utilized to relate the observed range of mechanical properties to the structure. In addition, the elastomeric nature has been established with the use of creep and recovery measurements. Such elastomers may find a variety of biomedical applications, ranging from stent coatings to atrial septal defect occluders.

  7. Self-Consistent Field Theory for the Design of Thermoplastic Elastomers from Miktoarm Block Copolymer - Homopolymer Blends

    NASA Astrophysics Data System (ADS)

    Hamilton, Andrew Lawrence

    We have used self-consistent field theory to study the morphological characteristics of blends of miktoarm block copolymers and homopolymers. More specifically, we have studied the effects of segregation strength, miktoarm block copolymer composition, and homopolymer size and volume fraction on the phase diagrams of these systems. A15 domains with discrete A-monomer spherical domains were found to be stable with A-monomer loading fractions of at least as high as 52%. Hexagonally-packed cylindrical domains were found to be stable at A-monomer loadings of at least as high as 72%. These findings represent a significant improvement from the loading fractions of 43% and 60% reported by Lynd et al. for spherical and cylindrical domains in neat miktoarm block copolymers, respectively. It is also quite possible that even greater loading fractions are achievable in systems too large for our simulations. These results predict exciting new materials for next-generation thermoplastic elastomers, since the ideal TPE has a large loading of A monomers in discrete, crystalline or glassy domains, surrounded by a continuous matrix of elastomeric B domains. Additionally, we have performed SCFT simulations modelled after experimental blends of polystyrene and polyisoprene-based miktoarm block copolymers and homopolymers. Certain experimental samples showed fascinating new "bricks and mortar" phases and swollen asymmetric lamellar phases. In both cases, the A domains are highly swollen with homopolymer, forcing the miktoarm block copolymer to segregate near the interface and adopt the role of a surfactant. The resulting structures maintain separate A and B domains, but lack long-range order. While it is not possible to study these mesophases using SCFT, since they lack long-range order and therefore well-defined symmetry, our SCFT results show the onset of macrophase separation at similar homopolymer loadings, for both the bricks and mortar phases and the highly swollen lamellae. This

  8. Heat shrinkability of electron-beam-modified thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer and polyethylene

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Chaki, T. K.; Bhowmick, Anil K.

    2000-11-01

    The heat shrinkability of electron-beam-irradiated thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer (EVA) and low-density polyethylene (LDPE) has been investigated in this paper. The effects of temperature, time and extent of stretching and shrinkage temperature and time have been reported. Based on the above data, the optimized conditions in terms of high heat shrinkage and low amnesia rating have been evaluated. Influence of radiation doses (0-500 kGy), multifunctional sensitizer levels (ditrimethylol propane tetraacrylate, DTMPTA), and blend proportions on heat shrinkability has been explained with the help of gel fraction and X-ray data. With the increase in radiation dose, gel fraction increases, which in turn gives rise to low values of heat shrinkage and amnesia rating. At a constant radiation dose and blend ratio, percent heat shrinkage is found to decrease with increase in DTMPTA level. Gel content increases with the increase in EVA content of the blend at a constant radiation dose and monomer level, giving rise to decrease in heat shrinkability. Heat shrinkage increases with the increase in percent crystallinity, although the amnesia rating follows the reverse trend.

  9. Investigation into the structure-property relationship and technical properties of TPEs and TPVs derived from ethylene octene copolymer (EOC) and polydimethyl siloxane (PDMS) rubber blends

    NASA Astrophysics Data System (ADS)

    Padmanabhan, R.; Naskar, Kinsuk; Nando, Golok B.

    2015-10-01

    This work focuses on the study of thermoplastic vulcanizates based on ethylene octene copolymer (EOC) and poly dimethyl siloxane (PDMS) rubber prepared by melt mixing technique using dicumyl peroxide (DCP). It is found that the addition of peroxide causes crosslinking in both the phases. However, crosslinking without affecting the crystallinity of the EOC polymer leads to tremendous improvement in the mechanical properties, including the tensile strength which has improved by nearly 60%. For better understanding about the crosslinking characteristics of thermoplastic vulcanizates (TPVs), significant correlation has been made between the vulcanized network and the physico-mechanical properties. Further, the dynamic mechanical properties and creep behavior of these thermoplastic elastomers (TPEs) and TPVs have also been studied. It is inferred that the TPVs show a 19% decrease in the creep compliance, i.e. higher creep resistance compared to uncrosslinked blends. Subsequently, the morphology of the blends before and after vulcanization shows a decrease in the spherical PDMS domains from 0.8 μm to > 0.4 μm. Ageing and reprocessing studies of the prepared TPVs also show better physico-mechanical properties even after reprocessing twice. Thus, the prepared TPVs may have tremendous applications in automobile sectors.

  10. Deformational characteristics of thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Indukuri, Kishore K.

    This thesis focuses primarily on the structure-property relationships of poly (styrene-ethylene-butylene-styrene) triblock copolymer TPEs. First evidence for strain-induced crystallization occurring in certain SEBS block copolymers has been established using unique techniques like deformation calorimetry, combined in-situ small angle X-ray and wide angle X-ray diffraction (SAXD/WAXD). Also the ramifications of such strain-induced crystallization on the mechanical properties like cyclic hysteresis, stress relaxation/creep retention of these SEBS systems have been studied. In addition, the structural changes in the morphology of these systems on deformation have been investigated using combined SAXD/WAXD setup. Small angle X-ray diffraction probed the changes at the nano-scale of polystyrene (PS) cylinders, while wide angle X-ray diffraction probed the changes at molecular length scales of the amorphous/crystalline domains of the elastomeric mid-block in these systems. New structural features at both these length scales have been observed and incorporated into the overall deformation mechanisms of the material. Continuous processing techniques like extrusion have been used to obtain ultra long-range order and orientation in these SEBS systems. Thus well ordered crystal like hexagonal packing of cylinders, where in each element in this hexagonal lattice can be individually addressed without any grain boundaries can be realized using these robust techniques. The effect of long-range order/orientation on the mechanical properties has been studied. In addition, these well ordered systems serve as model systems for evaluating deformation mechanisms of these SEBS systems, where the relative contributions of each of the phases can be estimated. EPDM/i-PP thermoplastic vulcanizates (TPVs) have micron size scale phase separated morphologies of EPDM rubber dispersed in a semicrystalline i-PP matrix as a result of the dynamic vulcanization process. Confocal microscopy studies

  11. Thermoplastic rubberlike material produced at low cost

    NASA Technical Reports Server (NTRS)

    Hendel, F. J.

    1966-01-01

    Thermoplastic rubberlike material is prepared by blending a copolymer of ethylene and vinyl acetate with asphalt and a petroleum distillate. This low cost material is easily molded or extruded and is compatible with a variety of fillers.

  12. Neutron absorbing room temperature vulcanizable silicone rubber compositions

    DOEpatents

    Zoch, Harold L.

    1979-11-27

    A neutron absorbing composition comprising a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide.

  13. Lignin poly(lactic acid) copolymers

    DOEpatents

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  14. Basic physical properties/structure of polystyrene-polyisobutylene-polystyrene triblock copolymers

    SciTech Connect

    Kaszas, G.

    1993-12-31

    Polystyrene-b-polyisobutylene-b-polystyrene (PSt-PIB-PSt) triblock copolymers, with various molecular architectures, have been synthesized to establish basic physical properties/structure correlations for this novel thermoplastics elastomer (TPE). The test results have confirmed that these triblock copolymers have a unique combination of physical properties which is currently unavailable on the TPE market. The fully saturated character of the PIB backbone provides excellent ozone resistance. Barrier, electrical, and low-temperature properties, were measured, and found to be equivalent to those of conventional butyl vulcanizates. The low initial modules of PIB, and the fact that the PSt content can be kept low without significant loss in tensile properties, renders the material soft. The high incompatibility of PIB and PSt allows the overall chain length and, therefore, the melt viscosity, to be kept low. This could bring an important advantage, in processing, over other TPE`s. The combination of the above properties, and the inherent properties of PIB, makes this material in excellent candidate for wire and cable coating, seal and gasket, adhesive and vibration damping applications.

  15. Tough, soluble, aromatic, thermoplastic copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    1994-01-01

    Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as acetamide, Nmethylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

  16. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... *Polyimides *Polypropylene Resins Polystyrene (Crystal) Polystyrene (Crystal) Modified *Polystyrene—Copolymers...

  17. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... *Polyimides *Polypropylene Resins Polystyrene (Crystal) Polystyrene (Crystal) Modified *Polystyrene—Copolymers...

  18. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... *Polyimides *Polypropylene Resins Polystyrene (Crystal) Polystyrene (Crystal) Modified *Polystyrene—Copolymers...

  19. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... *Polyimides *Polypropylene Resins Polystyrene (Crystal) Polystyrene (Crystal) Modified *Polystyrene—Copolymers...

  20. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... *Polyimides *Polypropylene Resins Polystyrene (Crystal) Polystyrene (Crystal) Modified *Polystyrene—Copolymers...

  1. Polyamide copolymers having 2,5-furan dicarboxamide units

    DOEpatents

    Chisholm, Bret Ja; Samanta, Satyabrata

    2017-09-19

    Polyamide copolymers, and methods of making and using polyamide copolymers, having 2,5-furan dicarboxamide units are disclosed herein. Such polymers can be useful for engineering thermoplastics having advantageous physical and/or chemical properties.

  2. Tough, Soluble, Aromatic, Thermoplastic Copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    1998-01-01

    Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

  3. The role of water on the structure and mechanical properties of a thermoplastic natural block co-polymer from squid sucker ring teeth.

    PubMed

    Rieu, Clément; Bertinetti, Luca; Schuetz, Roman; Salinas-Zavala, Cesar Ca; Weaver, James C; Fratzl, Peter; Miserez, Ali; Masic, Admir

    2016-09-02

    Hard biological polymers exhibiting a truly thermoplastic behavior that can maintain their structural properties after processing are extremely rare and highly desirable for use in advanced technological applications such as 3D-printing, biodegradable plastics and robust composites. One exception are the thermoplastic proteins that comprise the sucker ring teeth (SRT) of the Humboldt jumbo squid (Dosidicus gigas). In this work, we explore the mechanical properties of reconstituted SRT proteins and demonstrate that the material can be re-shaped by simple processing in water and at relatively low temperature (below 100 °C). The post-processed material maintains a high modulus in the GPa range, both in the dry and the wet states. When transitioning from low to high humidity, the material properties change from brittle to ductile with an increase in plastic deformation, where water acts as a plasticizer. Using synchrotron x-ray scattering tools, we found that water mostly influences nano scale structure, whereas at the molecular level, the protein structure remains largely unaffected. Furthermore, through simultaneous in situ x-ray scattering and mechanical tests, we show that the supramolecular network of the reconstituted SRT material exhibits a progressive alignment along the strain direction, which is attributed to chain alignment of the amorphous domains of SRT proteins. The high modulus in both dry and wet states, combined with their efficient thermal processing characteristics, make the SRT proteins promising substitutes for applications traditionally reserved for petroleum-based thermoplastics.

  4. Microscale patterning of thermoplastic polymer surfaces by selective solvent swelling.

    PubMed

    Rahmanian, Omid; Chen, Chien-Fu; DeVoe, Don L

    2012-09-04

    A new method for the fabrication of microscale features in thermoplastic substrates is presented. Unlike traditional thermoplastic microfabrication techniques, in which bulk polymer is displaced from the substrate by machining or embossing, a unique process termed orogenic microfabrication has been developed in which selected regions of a thermoplastic surface are raised from the substrate by an irreversible solvent swelling mechanism. The orogenic technique allows thermoplastic surfaces to be patterned using a variety of masking methods, resulting in three-dimensional features that would be difficult to achieve through traditional microfabrication methods. Using cyclic olefin copolymer as a model thermoplastic material, several variations of this process are described to realize growth heights ranging from several nanometers to tens of micrometers, with patterning techniques include direct photoresist masking, patterned UV/ozone surface passivation, elastomeric stamping, and noncontact spotting. Orogenic microfabrication is also demonstrated by direct inkjet printing as a facile photolithography-free masking method for rapid desktop thermoplastic microfabrication.

  5. Microscale Patterning of Thermoplastic Polymer Surfaces by Selective Solvent Swelling

    PubMed Central

    Rahmanian, Omid; Chen, Chien-Fu; DeVoe, Don L.

    2012-01-01

    A new method for the fabrication of microscale features in thermoplastic substrates is presented. Unlike traditional thermoplastic microfabrication techniques, in which bulk polymer is displaced from the substrate by machining or embossing, a unique process termed orogenic microfabrication has been developed in which selected regions of a thermoplastic surface are raised from the substrate by an irreversible solvent swelling mechanism. The orogenic technique allows thermoplastic surfaces to be patterned using a variety of masking methods, resulting in three-dimensional features that would be difficult to achieve through traditional microfabrication methods. Using cyclic olefin copolymer as a model thermoplastic material, several variations of this process are described to realize growth heights ranging from several nanometers to tens of microns, with patterning techniques include direct photoresist masking, patterned UV/ozone surface passivation, elastomeric stamping, and noncontact spotting. Orogenic microfabrication is also demonstrated by direct inkjet printing as a facile photolithography-free masking method for rapid desktop thermoplastic microfabrication. PMID:22900539

  6. Drying Thermoplastics

    NASA Technical Reports Server (NTRS)

    1976-01-01

    In searching for an improved method of removing water from polyester type resins without damaging the materials, Conair Inc. turned to the NASA Center at the University of Pittsburgh for assistance. Taking an organized, thorough look at existing technology before beginning research has helped many companies save significant time and money. They searched the NASA and other computerized files for microwave drying of thermoplastics. About 300 relevant citations were retrieved - eight of which were identified as directly applicable to the problem. Company estimates it saved a minimum of a full year in compiling research results assembled by the information center.

  7. Dynamically cured thermoplastic olefin polymers

    SciTech Connect

    Hazelton, D.R.; Puydak, R.C.; Booth, D.A.

    1986-08-19

    A thermoplastic composition is described comprising a polyolefin resin, a first rubber component selected from the group consisting of polyisobutylene, and ethylene propylene copolymer (EPM) and EPDM and a second rubber component selected from the group consisting of halogenated butyl rubber and polychoroprene, the second rubber component being cured utilizing a curative other than a peroxide, which is a vulcanizing agent for the second rubber but not for the first rubber, the second rubber being cured to a fully vulcanized state by dynamic vulcanization in the presence of the polyolefin resin and first rubber compound.

  8. Development of Internal Fine Structure in Stretched Rubber Vulcanizates

    SciTech Connect

    M Tosaka; S Toki; J Che; L Rong; B Hsiao

    2011-12-31

    Small-angle X-ray scattering (SAXS) pattern and tensile stress during relaxation of stretched rubber vulcanizates (synthetic polyisoprene) were measured simultaneously at room temperature and at 0 C. The samples were quickly stretched to the prefixed strain and then allowed to relax for 1 h. In every SAXS pattern, the intensity distribution was elongated along the equator, indicating the formation of structures elongated in the stretching direction. The so-called two-spots pattern corresponding to the long period of stacked lamellar crystals did not appear even when the critical strain to induce crystallization was exceeded. On the other hand, even below the critical strain, additional development of equatorial streaks was detected in the differential SAXS patterns. This result suggests the growth of the density fluctuation elongated in the stretching direction, which is not directly related to strain-induced crystallization.

  9. Development of Lignin-Based Polyurethane Thermoplastics

    SciTech Connect

    Saito, Tomonori; Perkins, Joshua H; Jackson, Daniel C; Trammell, Neil E; Hunt, Marcus A; Naskar, Amit K

    2013-01-01

    In our continued effort to develop value-added thermoplastics from lignin, here we report utilizing a tailored feedstock to synthesize mechanically robust thermoplastic polyurethanes at very high lignin contents (75 65 wt %). The molecular weight and glass transition temperature (Tg) of lignin were altered through cross-linking with formaldehyde. The cross-linked lignin was coupled with diisocyanate-based telechelic polybutadiene as a network-forming soft segment. The appearance of two Tg s, around 35 and 154 C, for the polyurethanes indicates the existence of two-phase morphology, a characteristic of thermoplastic copolymers. A calculated Flory-Huggins interaction parameter of 7.71 also suggests phase immiscibility in the synthesized lignin polyurethanes. An increase in lignin loading increased the modulus, and an increase in crosslink-density increased the modulus in the rubbery plateau region of the thermoplastic. This path for synthesis of novel lignin-based polyurethane thermoplastics provides a design tool for high performance lignin-based biopolymers.

  10. A nanostructured carbon-reinforced polyisobutylene-based thermoplastic elastomer.

    PubMed

    Puskas, Judit E; Foreman-Orlowski, Elizabeth A; Lim, Goy Teck; Porosky, Sara E; Evancho-Chapman, Michelle M; Schmidt, Steven P; El Fray, Mirosława; Piatek, Marta; Prowans, Piotr; Lovejoy, Krystal

    2010-03-01

    This paper presents the synthesis and characterization of a polyisobutylene (PIB)-based nanostructured carbon-reinforced thermoplastic elastomer. This thermoplastic elastomer is based on a self-assembling block copolymer having a branched PIB core carrying -OH functional groups at each branch point, flanked by blocks of poly(isobutylene-co-para-methylstyrene). The block copolymer has thermolabile physical crosslinks and can be processed as a plastic, yet retains its rubbery properties at room temperature. The carbon-reinforced thermoplastic elastomer had more than twice the tensile strength of the neat polymer, exceeding the strength of medical grade silicone rubber, while remaining significantly softer. The carbon-reinforced thermoplastic elastomer displayed a high T(g) of 126 degrees C, rendering the material steam-sterilizable. The carbon also acted as a free radical trap, increasing the onset temperature of thermal decomposition in the neat polymer from 256.6 degrees C to 327.7 degrees C. The carbon-reinforced thermoplastic elastomer had the lowest water contact angle at 82 degrees and surface nano-topography. After 180 days of implantation into rabbit soft tissues, the carbon-reinforced thermoplastic elastomer had the thinnest tissue capsule around the microdumbbell specimens, with no eosinophiles present. The material also showed excellent integration into bones. Copyright 2009 Elsevier Ltd. All rights reserved.

  11. Dielectric Relaxation Behavior of Exfoliated Graphite Nanoplatelet-Filled EPDM Vulcanizates

    NASA Astrophysics Data System (ADS)

    Dash, Bikash Kumar; Achary, P. Ganga Raju; Nayak, Nimai C.; Choudhary, R. N. P.

    2017-01-01

    The present study investigates the dielectric relaxation and mechanical behavior of exfoliated graphite nanoplatelet (XgnP)-filled ethylene-propylene-diene terpolymer (EPDM) vulcanizates with variation in frequency, temperature and xGnP loading. The samples were prepared by a solution-cast method using toluene as the solvent followed by compression molding. The enhanced permittivity and ac conductivity which sharply changes above 20 wt.% of xGnP loading shows the conducting behavior of the composites. The real parts of the impedance for the vulcanizates were continuously decreased up to 40 wt.% whereas the complex part shows an increasing tendency at the same loading expressing the increase in the conductivity of the vulcanizates. The percolation threshold of the xGnP-loaded EPDM vulcanizates was at 25 wt.% of xGnP loading. A more prominent effect of temperature on dielectric loss tangent is observed at 85°C, and 100°C. The ac conductivity increases with the rise in temperature. The Nyquist plots of xGnP-reinforced EPDM show the small intercepts on the Z' axis at 85°C, and 100°C for the 40 wt.% loading. The experimental complex impedance plots were in good agreement with the model-fitted plots. The tensile strength of 15 wt.% xGnP-filled vulcanizate increases up to 12 times more than the unfilled EPDM whereas the elongation at break (%) increases up to 700% at the same loading of xGnP. Young's modulus has been doubled and quadrupled for the vulcanizates with 20 and 40 wt.% of xGnPs, respectively, compared to the pure EPDM samples. The results indicate that the xGnP-EPDM conductive composite can find applications in the area of antistatic material, electrostatic discharge gaskets, etc.

  12. Polyolefin Thermoplastics for Multiple Shape and Reversible Shape Memory.

    PubMed

    Gao, Yuan; Liu, Weifeng; Zhu, Shiping

    2017-02-08

    This work reports the first pure hydrocarbon thermoplastic polyolefin material with reversible shape memory effect under stress-free or very small external loading condition. A thermoplastic ethylene/1-octene diblock copolymer with designed chain microstructure was synthesized. The polyolefin material performed not only the conventional one-way multishape memory effects, but also a two-way reversible shape memory effect (RSME). The elongation and contraction induced by oriented crystallization with heating was confirmed as the mechanism of RSME without chemical cross-linking. This work demonstrated that the thermoplastic reversible shape memory could be achieved through careful design of chain microstructure, based on sole hydrocarbon materials such as ethylene-1-octene copolymer.

  13. Polystyrene/wood composites and hydrophobic wood coatings from water-based hydrophilic-hydrophobic block copolymers

    Treesearch

    Marja-Leena Kosonen; Bo Wang; Gerard T. Caneba; Douglas J. Gardner; Tim G. Rials

    2000-01-01

    The combination of synthetic thermoplastic polymers and wood is normally problematic because wood surfaces are hydrophilic while typical thermoplastic polymers are hydrophobic. A possible solution is to use block copolymer coupling agents. In this work we show the use of a potentially useful synthetic method of producing hydrophilic-hydrophobic block copolymers as...

  14. Pen microfluidics: rapid desktop manufacturing of sealed thermoplastic microchannels.

    PubMed

    Rahmanian, Omid; DeVoe, Don L

    2013-03-21

    A unique technique for the rapid fabrication of thermoplastic microfluidic chips is described. The method enables the realization of fully-sealed microchannels in around one hour while requiring only minimal infrastructure by taking advantage of a solvent swelling mechanism that allows raised features to be patterned on the surface of homogeneous thermoplastic materials. Patterning is achieved without photolithography by simply drawing the desired microchannel pattern onto the polymer surface using a suitable ink as a masking layer, either manually or under robotic control, followed by timed exposure to solvent vapor to yield a desired depth for the masked channel features. The channels are then permanently sealed through solvent bonding of the microchannel chip to a mating thermoplastic substrate. The process is demonstrated using cyclic olefin copolymer as a thermoplastic material, with fully operational microfluidic devices fabricated following a true desktop manufacturing model suitable for rapid prototyping.

  15. Pen microfluidics: rapid desktop manufacturing of sealed thermoplastic microchannels

    PubMed Central

    Rahmanian, Omid

    2013-01-01

    A unique technique for the rapid fabrication of thermoplastic microfluidic chips is described. The method enables the realization of fully-sealed microchannels in around one hour while requiring only minimal infrastructure by taking advantage of a solvent swelling mechanism that allows raised features to be patterned on the surface of homogeneous thermoplastic materials. Patterning is achieved without photolithography by simply drawing the desired microchannel pattern onto the polymer surface using a suitable ink as a masking layer, either manually or under robotic control, followed by timed exposure to solvent vapor to yield a desired depth for the masked channel features. The channels are then permanently sealed through solvent bonding of the microchannel chip to a mating thermoplastic substrate. The process is demonstrated using cyclic olefin copolymer as a thermoplastic material, with fully operational microfluidic devices fabricated following a true desktop manufacturing model suitable for rapid prototyping. PMID:23344819

  16. Tough soluble aromatic thermoplastic copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    2000-01-01

    Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. Alternatively, these copolyimides may be prepared by reacting 4,4'-oxydiphthalic anhydride with 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydiisocyanate. Also, the copolyimide may be prepared by reacting the corresponding tetra acid and ester precursors of 4,4'-oxydiphthalic anhydride and 3,4,3',4'-biphenyltetracarboxylic dianhydride with 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

  17. Thermoforming of thermoplastic composites

    NASA Astrophysics Data System (ADS)

    McKillop, Brian E.

    Although originally devised for forming unreinfored thermoplastics in sheet form, thermoforming it has been successfully adapted to continuous reinforced thermoplastic composite materials. The conversion rate of this technique is limited only by how fast heat can be added to the thermoplastic matrix to bring it to the processing temperature and the rate at which heat can be removed from the material after the forming process has been completed. Load-to-load cycle times of four minutes have been demonstrated. Processing procedures, equipment, tooling, design consideration and applications are presented to demonstrate that thermoplastic composites can be successfully thermoformed into practical shapes.

  18. Thermoplastic welding apparatus and method

    DOEpatents

    Matsen, Marc R.; Negley, Mark A.; Geren, William Preston; Miller, Robert James

    2017-03-07

    A thermoplastic welding apparatus includes a thermoplastic welding tool, at least one tooling surface in the thermoplastic welding tool, a magnetic induction coil in the thermoplastic welding tool and generally encircling the at least one tooling surface and at least one smart susceptor in the thermoplastic welding tool at the at least one tooling surface. The magnetic induction coil is adapted to generate a magnetic flux field oriented generally parallel to a plane of the at least one smart susceptor.

  19. Baroplastic Block copolymers

    NASA Astrophysics Data System (ADS)

    Hewlett, Sheldon A.

    2005-03-01

    Block copolymers with rubbery and glassy components have been observed to have pressure induced miscibility. These microphase-separated materials, termed baroplastics, were able to flow and be processed at temperatures below the Tg of the glassy component by simple compression molding and extrusion. Diblock and triblock copolymers of polystyrene and poly(butyl acrylate) or poly(2-ethyl hexyl acrylate) were synthesized by atom transfer radical polymerization (ATRP) and processed at room temperature into well defined transparent objects. SAXS and SANS measurements demonstrated partial mixing between components as a result of pressure during processing. DSC results also show the presence of distinct domains even after several processing cycles. Their mechanical properties after processing were tested and compared with commercial thermoplastic elastomers.

  20. Ten-Year Aging of Elastomeric Vulcanizates in Panama, Alaska, and Illinois

    DTIC Science & Technology

    1974-07-01

    Rycar h021 { Zk ^JF), and Genthane SR (Z60DU) vulcanizates where tensile strength deterioration is the best cri- terion of the change which takes...reversion over a period of many months., The cracking appears to result from microbiological attack. The hydrolytic decomposition of polyester urethanes...Commander U. S. Army Medical Biomechanical Research Laboratory ATTN: Library Fort Detrick, Bldg. 56ö Frederick, MD 21701 Commander Natick

  1. Preparation of sulfonic acid-containing rubbers from natural rubber vulcanizates

    NASA Astrophysics Data System (ADS)

    Poonsawat, Worapong; Poompradub, Sirilux; Ngamcharussrivichai, Chawalit

    2014-06-01

    In this work, a series of sulfonic acid-containing rubbers were prepared by aqueous phase oxidation of natural rubber vulcanizates in the presence of hydrogen peroxide (H2O2) and formic acid (HCOOH). The starting vulcanizates were neatly prepared via an efficient vulcanization (EV) system by varying mass ratio of N-cyclohexyl-2-benzothiazole sulfonamide (CBS), as an accelerator, to sulfur. The oxidation conditions were controlled at the molar ratio of H2O2: HCOOH = 1:1, the concentration of H2O2 = 15 wt.%, the temperature = 50 °C, and the reaction time = 3 h. The rubber materials before and after the oxidation were characterized for their physicochemical properties by using Fourier transform infrared spectroscopy, bomb calorimetry, acid-base titration and swelling measurements. The results indicated the presence of sulfonic acid group in the oxidized rubbers, generated by the oxidative cleaves of sulfide crosslinks in the rubber vulcanizates. The oxidation decreased the sulfur content of the rubber in which the level of sulfur loss was determined by the CBS/sulfur ratio. Moreover, the acidity of the oxidized products was correlated with the amount of sulfur remaining.

  2. Morphology and vulcanizate properties of ethylene-propylene-diene rubber/ styrene-butadiene rubber blends.

    PubMed

    Park, Gayoung; Kim, Yun Hee; Kim, Dong Soo; Ko, Young Chun

    2010-05-01

    Morphology and vulcanizate properties of EPDM/SBR blends were investigated. AAHR (a mixture of aliphatic and aromatic hydrocarbon resins) was used as a compatibilizer and bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) was used as a coupling agent. The vulcanizate properties and the morphological studies revealed that EPDM and SBR were incompatible, and the addition of AAHR was very effective to enhance the compatibility between EPDM and SBR. The weight percent of bound rubbers was increased with increasing SBR contents. The addition of an AAHR increased the amounts of bound rubbers, and hence the vulcanizate properties such as tear strength and fatigue resistance of the EPDM/SBR blends were improved. The dynamic mechanical analysis and the morphological studies revealed that the addition of TESPT increased the weight of bound rubbers and provided better dispersion of carbon black, resulting in good mechanical properties such as tear strength and fatigue resistance of the vulcanized EPDM/SBR blends. The smaller particle of zinc oxide (i.e., 50 nm > 100 nm > 1000 nm) yielded to the better blending properties of the polymer blend.

  3. Effect of silica nanoparticles on reinforcement of poly(phenylene ether) based thermoplastic elastomer.

    PubMed

    Gupta, Samik; Maiti, Parnasree; Krishnamoorthy, Kumar; Krishnamurthy, Raja; Menon, Ashok; Bhowmick, Anil K

    2008-04-01

    Reinforcement of a novel poly(phenylene ether) (PPE) based thermoplastic elastomer (TPE), i.e., styrene-ethylene-butylene-styrene (SEBS)/ethylene vinyl acetate (EVA) and PPE-polystyrene (PS), was studied to develop a reinforced thermoplastic elastomer or thermoplastic vulcanizate (TPV). An effort was made to reinforce selectively the elastomeric dispersed phase of EVA by silica nanoparticles and silica sol-gel precursors, like alkoxy orthosilanes, using twin-screw extrusion and injection molding processes. Improvement of tensile strength and percent elongation at break was observed both with silica nanoparticles and tetraethoxy orthosilane (TEOS). Addition of TEOS transformed the dispersed EVA lamellar morphology into semispherical domains as a consequence of possible crosslinking. Soxhlet extraction was done on the silica and TEOS reinforced materials. The insoluble residues collected from both the silica and TEOS reinforced samples were analyzed in detail using both morphological and spectroscopic studies. This extensive study also provided an in-depth conceptual understanding of the PPE based TPE behavior upon reinforcement with silica nanoparticles and silica sol-gel precursors and the effect of reinforcement on recycling behavior.

  4. Lignin-Based Thermoplastic Materials.

    PubMed

    Wang, Chao; Kelley, Stephen S; Venditti, Richard A

    2016-04-21

    Lignin-based thermoplastic materials have attracted increasing interest as sustainable, cost-effective, and biodegradable alternatives for petroleum-based thermoplastics. As an amorphous thermoplastic material, lignin has a relatively high glass-transition temperature and also undergoes radical-induced self-condensation at high temperatures, which limits its thermal processability. Additionally, lignin-based materials are usually brittle and exhibit poor mechanical properties. To improve the thermoplasticity and mechanical properties of technical lignin, polymers or plasticizers are usually integrated with lignin by blending or chemical modification. This Review attempts to cover the reported approaches towards the development of lignin-based thermoplastic materials on the basis of published information. Approaches reviewed include plasticization, blending with miscible polymers, and chemical modifications by esterification, etherification, polymer grafting, and copolymerization. Those lignin-based thermoplastic materials are expected to show applications as engineering plastics, polymeric foams, thermoplastic elastomers, and carbon-fiber precursors.

  5. UV-absorbent lignin-based multi-arm star thermoplastic elastomers.

    PubMed

    Yu, Juan; Wang, Jifu; Wang, Chunpeng; Liu, Yupeng; Xu, Yuzhi; Tang, Chuanbing; Chu, Fuxiang

    2015-02-01

    Lignin-grafted copolymers, namely lignin-graft-poly(methyl methacrylate-co-butyl acrylate) (lignin-g-P(MMA-co-BA)), are synthesized via "grafting from" atom transfer radical polymerization (ATRP) with the aid of lignin-based macroinitiators. By manipulating the monomer feed ratios of MMA/BA, grafted copolymers with tunable glass transition temperatures (-10-40 °C) are obtained. These copolymers are evaluated as sustainable thermoplastic elastomers (TPEs). The results suggest that the mechanical properties of these TPEs lignin-g-P(MMA-co-BA) copolymers are improved significantly by comparing with those of linear P(MMA-co-BA) copolymer counterparts, and the elastic strain recovery is nearly 70%. Lignin-g-P(MMA-co-BA) copolymers exhibit high absorption in the range of the UV spectrum, which might allow for applications in UV-blocking coatings.

  6. Wood thermoplastic composites

    Treesearch

    Daniel F. Caulfield; Craig Clemons; Roger M. Rowell

    2010-01-01

    The wood industry can expand into new sustainable markets with the formation of a new class of composites with the marriage of the wood industry and the plastics industry. The wood component, usually a flour or fiber, is combined with a thermoplastic to form an extrudable, injectable or thermoformable composite that can be used in many non-structural applications....

  7. Wood thermoplastic composites

    Treesearch

    Daniel F. Caulfield; Craig Clemons; Rodney E. Jacobson; Roger M. Rowell

    2005-01-01

    The term “wood-plastic composites” refers to any number of composites that contain wood (of any form) and either thermoset or thermoplastic polymers. Thermosets or thermoset polymers are plastics that, once cured, cannot be remelted by heating. These include cured resins, such as epoxies and phenolics, plastics with which the forest products industry is most familiar (...

  8. High temperature thermoplastic elastomers synthesized by living anionic polymerization in hydrocarbon solvent at room temperature

    DOE PAGES

    Schlegel, Ralf; Williams, Katherine; Voyloy, Dimitry; ...

    2016-03-30

    We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (Tg) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffinemore » tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. Additionally, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy.« less

  9. High temperature thermoplastic elastomers synthesized by living anionic polymerization in hydrocarbon solvent at room temperature

    SciTech Connect

    Schlegel, Ralf; Williams, Katherine; Voyloy, Dimitry; Steren, Carlos A.; Goodwin, Andrew; Coughlin, E. Bryan; Gido, Samuel; Beiner, Mario; Hong, Kunlun; Kang, Nam -Goo; Mays, Jimmy; Wang, Weiyu; White, Benjamin T.

    2016-03-30

    We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (Tg) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffine tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. Additionally, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy.

  10. Process Makes Thermoplastic Prepreg Ribbon

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Johnson, Gary S.

    1995-01-01

    Manufacturing process produces ribbon of composite material (prepreg) consisting of continuous lengthwise fibers impregnated with thermoplastic resin. Ribbon can later be cut into sheets of required sizes and shapes, stacked, then heated under pressure to form composite-material structural components. Process accommodates variety of thermoplastic resins and variety of fibers.

  11. Reinforcement of SBR/waste rubber powder vulcanizate with in situ generated zinc dimethacrylate

    NASA Astrophysics Data System (ADS)

    Wang, X. P.; Cheng, B. K.; Zhang, X.; Jia, D. M.

    2016-07-01

    Methyl acrylic acid/zinc oxide (MAA/ZnO) was introduced to modify styrene- butadiene rubber/waste rubber powder (SBR/WRP) composites by blending. The enhanced mechanical properties and processing ability were presumably originated from improved compatibility and interfacial interaction between WRP and the SBR matrix by the in situ polymerization of zinc dimethacrylate (ZDMA). A refined interface of the modified SBR/WRP composite was observed by scanning electron microscopy. The formation of ZDMA significantly increased the ionic bond content in the vulcanizate, resulting in exceptional mechanical performance. The comprehensive mechanical properties including tensile strength, tear strength and dynamic heat-building performance reached optimum values with 16 phr MAA.

  12. Bonding thermoplastic polymers

    SciTech Connect

    Wallow, Thomas I.; Hunter, Marion C.; Krafcik, Karen Lee; Morales, Alfredo M.; Simmons, Blake A.; Domeier, Linda A.

    2008-06-24

    We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.

  13. THERMOPLASTIC WAVES IN MAGNETARS

    SciTech Connect

    Beloborodov, Andrei M.; Levin, Yuri E-mail: yuri.levin@monash.edu.au

    2014-10-20

    Magnetar activity is generated by shear motions of the neutron star surface, which relieve internal magnetic stresses. An analogy with earthquakes and faults is problematic, as the crust is permeated by strong magnetic fields which greatly constrain crustal displacements. We describe a new deformation mechanism that is specific to strongly magnetized neutron stars. The magnetically stressed crust begins to move because of a thermoplastic instability, which launches a wave that shears the crust and burns its magnetic energy. The propagating wave front resembles the deflagration front in combustion physics. We describe the conditions for the instability, the front structure, and velocity, and discuss implications for observed magnetar activity.

  14. Multiple-length-scale deformation analysis in a thermoplastic polyurethane

    PubMed Central

    Sui, Tan; Baimpas, Nikolaos; Dolbnya, Igor P.; Prisacariu, Cristina; Korsunsky, Alexander M.

    2015-01-01

    Thermoplastic polyurethane elastomers enjoy an exceptionally wide range of applications due to their remarkable versatility. These block co-polymers are used here as an example of a structurally inhomogeneous composite containing nano-scale gradients, whose internal strain differs depending on the length scale of consideration. Here we present a combined experimental and modelling approach to the hierarchical characterization of block co-polymer deformation. Synchrotron-based small- and wide-angle X-ray scattering and radiography are used for strain evaluation across the scales. Transmission electron microscopy image-based finite element modelling and fast Fourier transform analysis are used to develop a multi-phase numerical model that achieves agreement with the combined experimental data using a minimal number of adjustable structural parameters. The results highlight the importance of fuzzy interfaces, that is, regions of nanometre-scale structure and property gradients, in determining the mechanical properties of hierarchical composites across the scales. PMID:25758945

  15. Graphite fiber reinforced thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1975-01-01

    Mechanical properties of neat resin samples and graphite fiber reinforced samples of thermoplastic resins were characterized with particular emphasis directed to the effects of environmental exposure (humidity, temperature and ultraviolet radiation). Tensile, flexural, interlaminar shear, creep and impact strengths were measured for polysulfone, polyarylsulfone and a state-of-the-art epoxy resin samples. In general, the thermoplastic resins exhibited environmental degradation resistance equal to or superior to the reference epoxy resin. Demonstration of the utility and quality of a graphite/thermoplastic resin system was accomplished by successfully thermoforming a simulated compressor blade and a fan exit guide vane.

  16. Thermoplastic coating of carbon fibers

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Lickfield, G. C.; Drews, M. J.; Ellison, M. S.; Gantt, B. W.

    1989-01-01

    A process is being developed which evenly coats individual carbon fibers with thermoplastic polymers. In this novel, continuous coating process, the fiber tow bundle is first spread cover a series of convex rollers and then evenly coated with a fine powder of thermoplastic matrix polymer. Next, the fiber is heated internally by passing direct current through the powder coated fiber. The direct current is controlled to allow the carbon fiber temperature to slightly exceed the flow temperature of the matrix polymer. Analysis of the thermoplastic coated carbon fiber tows produced using this continuous process indicates that 30 to 70 vol pct fiber prepregs can be obtained.

  17. Processable Aromatic Polyimide Thermoplastic Blends

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M; Johnston, Norman J.; St. Clair, Terry L.; Nelson, James B.; Gleason, John R.; Proctor, K. Mason

    1988-01-01

    Method developed for preparing readily-processable thermoplastic polyimides by blending linear, high-molecular-weight, polyimic acid solutions in ether solvents with ultrafine, semicrystalline, thermoplastic polyimide powders. Slurries formed used to make prepregs. Consolidation of prepregs into finsihed composites characterized by excellent melt flow during processing. Applied to film, fiber, fabric, metal, polymer, or composite surfaces. Used to make various stable slurries from which prepregs prepared.

  18. Graphite/Thermoplastic-Pultrusion Die

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Frye, Mark W.; Johnson, Gary S.; Stanfield, Clarence E.

    1990-01-01

    Attachment to extruder produces thermoplastic-impregnated graphite tape. Consists of profile die, fiber/resin collimator, and crosshead die body. Die designed to be attached to commercially available extrusion machine capable of extruding high-performance thermoplastics. Simple attachment to commercial extruder enables developers of composites to begin experimenting with large numbers of proprietary resins, fibers, and hybrid composite structures. With device, almost any possible fiber/resin combination fabricated.

  19. Graphite/Thermoplastic-Pultrusion Die

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Frye, Mark W.; Johnson, Gary S.; Stanfield, Clarence E.

    1990-01-01

    Attachment to extruder produces thermoplastic-impregnated graphite tape. Consists of profile die, fiber/resin collimator, and crosshead die body. Die designed to be attached to commercially available extrusion machine capable of extruding high-performance thermoplastics. Simple attachment to commercial extruder enables developers of composites to begin experimenting with large numbers of proprietary resins, fibers, and hybrid composite structures. With device, almost any possible fiber/resin combination fabricated.

  20. Poly(butylene succinate) and its copolymers: research, development and industrialization.

    PubMed

    Xu, Jun; Guo, Bao-Hua

    2010-11-01

    Poly(butylene succinate) (PBS) and its copolymers are a family of biodegradable polymers with excellent biodegradability, thermoplastic processability and balanced mechanical properties. In this article, production of the monomers succinic acid and butanediol, synthesis, processing and properties of PBS and its copolymers are reviewed. The physical properties and biodegradation rate of PBS materials can be varied in a wide range through copolymerization with different types and various contents of monomers. PBS has a wide temperature window for thermoplastic processing, which makes the resin suitable for extrusion, injection molding, thermoforming and film blowing. Finally, we summarized industrialization and applications of PBS.

  1. The devulcanization of unfilled and carbon black filled isoprene rubber vulcanizates by high power ultrasound

    NASA Astrophysics Data System (ADS)

    Sun, Ximei

    The effects of ultrasound on virgin gum isoprene rubber (IR) and on the devulcanization of unfilled and carbon black (CB) filled IR were studied. Ultrasonic treatment altered the structure and properties of gum IR by creating low molecular weight tails which broadened the molecular weight distribution and improved processability. Ultrasonic devulcanization of IR vulcanizates resulted in a reduction of gel fraction and crosslink density. Increasing the ultrasonic amplitude yielded a further reduction, regardless of CB loading, in the IR vulcanizates. This is contrary to the previous work on natural rubber (NR), the natural counterpart of IR which showed a minimum gel fraction and crosslink density at an intermediate ultrasonic amplitude. The devulcanization of filled IR resulted in more main chain scission than in unfilled IR due to the immobility of bound rubber at the filler surface which leads to lower properties in revulcanized rubbers than in virgin rubber. Upon blending the devulcanized IR with virgin IR, properties comparable to those of virgin rubber were obtained at certain blending ratios. A cure kinetics model with reversion adequately predicted the evolution of state of cure in curing and reversion stages under isothermal and non-isothermal conditions. The higher reversion observed in filled IR than in unfilled IR was consistent with the difference of reversion rate constant obtained in simulation. NMR proton transverse relaxation technique was unable to differentiate the contribution of short component mobility between physically entangled (heavy sol) and chemically crosslinked (gel) networks. Ultrasound severed both the chemical crosslinks and the main chain, creating dangling chain ends, with no generation of additional fragments of oligomeric species. Simulation of network structures using the Dobson-Gordon theory of network statistics indicated crosslinks were easier to break than main chains under ultrasonic exposure. Unfilled IR and NR had similar

  2. Thermoplastic tape compaction device

    DOEpatents

    Campbell, V.W.

    1994-12-27

    A device is disclosed for bonding a thermoplastic tape to a substrate to form a fully consolidated composite. This device has an endless chain associated with a frame so as to rotate in a plane that is perpendicular to a long dimension of the tape, the chain having pivotally connected chain links with each of the links carrying a flexible foot member that extends outwardly from the chain. A selected number of the foot members contact the tape, after the heating thereof, to cause the heated tape to bond to the substrate. The foot members are each a thin band of metal oriented transversely to the chain, with a flexibility and width and length to contact the tape so as to cause the tape to conform to the substrate to achieve consolidation of the tape and the substrate. A biased leaf-type spring within the frame bears against an inner surface of the chain to provide the compliant pressure necessary to bond the tape to the substrate. The chain is supported by sprockets on shafts rotatably supported in the frame and, in one embodiment, one of the shafts has a drive unit to produce rotation such that the foot members in contact with the tape move at the same speed as the tape. Cooling jets are positioned along the frame to cool the resultant consolidated composite. 5 figures.

  3. Thermoplastic tape compaction device

    DOEpatents

    Campbell, Vincent W.

    1994-01-01

    A device for bonding a thermoplastic tape to a substrate to form a fully consolidated composite. This device has an endless chain associated with a frame so as to rotate in a plane that is perpendicular to a long dimension of the tape, the chain having pivotally connected chain links with each of the links carrying a flexible foot member that extends outwardly from the chain. A selected number of the foot members contact the tape, after the heating thereof, to cause the heated tape to bond to the substrate. The foot members are each a thin band of metal oriented transversely to the chain, with a flexibility and width and length to contact the tape so as to cause the tape to conform to the substrate to achieve consolidation of the tape and the substrate. A biased leaf-type spring within the frame bears against an inner surface of the chain to provide the compliant pressure necessary to bond the tape to the substrate. The chain is supported by sprockets on shafts rotatably supported in the frame and, in one embodiment, one of the shafts has a drive unit to produce rotation such that the foot members in contact with the tape move at the same speed as the tape. Cooling jets are positioned along the frame to cool the resultant consolidated composite.

  4. Advanced thermoplastic resins, phase 1

    NASA Technical Reports Server (NTRS)

    Hendricks, C. L.; Hill, S. G.; Falcone, A.; Gerken, N. T.

    1991-01-01

    Eight thermoplastic polyimide resin systems were evaluated as composite matrix materials. Two resins were selected for more extensive mechanical testing and both were versions of LaRC-TPI (Langley Research Center - Thermoplastic Polyimide). One resin was made with LaRC-TPI and contained 2 weight percent of a di(amic acid) dopant as a melt flow aid. The second system was a 1:1 slurry of semicrystalline LaRC-TPI powder in a polyimidesulfone resin diglyme solution. The LaRC-TPI powder melts during processing and increases the melt flow of the resin. Testing included dynamic mechanical analysis, tension and compression testing, and compression-after-impact testing. The test results demonstrated that the LaRC-TPI resins have very good properties compared to other thermoplastics, and that they are promising matrix materials for advanced composite structures.

  5. Graphite fiber reinforced thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Navak, R. C.

    1977-01-01

    The results of a program designed to optimize the fabrication procedures for graphite thermoplastic composites are described. The properties of the composites as a function of temperature were measured and graphite thermoplastic fan exit guide vanes were fabricated and tested. Three thermoplastics were included in the investigation: polysulfone, polyethersulfone, and polyarylsulfone. Type HMS graphite was used as the reinforcement. Bending fatigue tests of HMS graphite/polyethersulfone demonstrated a gradual shear failure mode which resulted in a loss of stiffness in the specimens. Preliminary curves were generated to show the loss in stiffness as a function of stress and number of cycles. Fan exit guide vanes of HMS graphite polyethersulfone were satisfactorily fabricated in the final phase of the program. These were found to have stiffness and better fatigue behavior than graphite epoxy vanes which were formerly bill of material.

  6. Structure and thermoplasticity of coal

    SciTech Connect

    Komaki, I.; Itagaki, S.; Miura, T.

    2004-07-01

    Chapters cover: molecular structure and thermoplastic properties of coal; {sup 1}H-nmr study of relaxation mechanisms of coal aggregate; structural changes of coal macromolecules during softening; quantitative estimation of metaplsat in heat-treated coal by solvent extraction; effects of surface oxidation on thermoplastic properties of coal; analysis of dilatation and contraction of coal during carbonization; formation mechanisms of coke texture during resolidification; modified CPD model for coal devolatilization; mathematical modelling of coke mechanical structure; and simulating particulate dynamics in the carbonization process based on discrete element treatment.

  7. Turning Renewable Resources into Recyclable Polymer: Development of Lignin-Based Thermoplastic

    SciTech Connect

    Saito, Tomonori; Brown, Rebecca H; Hunt, Marcus A; Pickel, Deanna L; Pickel, Joseph M; Messman, Jamie M; Baker, Frederick S; Keller, Martin; Naskar, Amit K

    2012-01-01

    Productive uses of lignin, the third most abundant natural polymer, have been sought for decades. One especially attractive possibility is that of developing value-added products including thermoplastics based on lignin. This possibility warrants special attention due to growth of the modern biofuel industries. However, the polydisperse molecular weight and hyper-branched structure of lignin has hindered the creation of high-performance biopolymers. Here, we report the preparation and characterization of novel lignin-based, partially carbon-neutral thermoplastics. We first altered the molecular weight of lignin, either by fractionation with methanol, or by formaldehyde crosslinking. A crosslinking of lignin increases the molecular weight, exhibiting Mn = 31000 g/mol, whereas that of native lignin is 1840 g/mol. Tuning the molecular weight of lignin enabled successful preparation of novel lignin-derived thermoplastics, when coupled with telechelic polybutadiene soft-segments at proper feed ratios. Characteristic to thermoplastic rubbers, free-standing films of the resulting copolymers exhibit two-phase morphology and associated relaxations in the dynamic mechanical loss spectrum. To our knowledge this article is the first report to demonstrate phase immiscibility, melt-processibility, and biphasic morphology of soft and hard segments in a lignin-based copolymer for all feed ratios of two macromolecular components. The use of higher molecular weight lignin enhanced the resulting shear modulus due to efficient network formation of telechelic polybutadiene bridges. The storage modulus in the rubbery plateau region increased with increasing lignin content. The successful synthesis of novel lignin-based thermoplastics will open a new pathway to biomass utilization and will help conserve petrochemicals.

  8. Multigraft Copolymer Superelastomers: Synthesis Morphology, and Properties

    SciTech Connect

    Uhrig, David; Schlegel, Ralf; Weidisch, Roland; Mays, Jimmy

    2011-01-01

    The synthesis of well-defined multigraft copolymers having a polydiene backbone with polystyrene side chains is briefly reviewed, with particular focus on controlling branch point spacing and branch point functionality. Use of living anionic polymerization and chlorosilane linking chemistry has led to the synthesis of series of materials having regularly spaced trifunctional (comb), tetrafunctional (centipede), and hexafunctional (barbwire) branch points. The morphologies of these materials were characterized by transmission electron microscopy and small-angle X-ray scattering, and it was found that the morphologies were controlled by the local architectural asymmetry associated with each branch point. Mechanical properties studies revealed that such multigraft copolymers represent a new class of thermoplastic elastomers (TPEs) with superior elongation at break and low residual strains as compared to conventional TPEs.

  9. Nano-Structural Elucidation in Carbon Black Loaded NR Vulcanizate by 3D-TEM and In Situ WAXD Measurements

    SciTech Connect

    Ikeda,Y.; Kato, A.; Shimanuki, J.; Kohjiya, S.; Tosaka, M.; Poompradub, S.; Toki, S.; Hsiao, B.

    2007-01-01

    Three dimensional (3D) visualization of nanometer structure of carbon black dispersion in rubbery matrix has successfully been studied and reported in this paper. Use of 3D-TEM, which is computerized tomography combined with transmission electron microscopy (TEM), enabled us to reconstruct 3D images of carbon black aggregates in natural rubber (NR) matrix. The TEM measurements were conducted by a bright-field method on thin samples without any electron staining. The sample was subject to uni-axial tilting (+65 degree to -65 degree with 2 degree increment) in the sample chamber, and 66 TEM images were taken on each sample. These TEM images were used for computerized tomography to reconstruct the 3D image. This technique is designated as 3D-TEM. The nano-structural features observed by 3D-TEM were in conformity with the electron-conductivity results, and the percolation behavior was recognized. These results were further supplemented by in situ wide-angle X-ray diffraction (WAXD), i.e., simultaneous WAXD and tensile measurements on the sample to observe the strain-induced crystallization in NR vulcanizate. Upon tensile elongation, the crystallization was clearly observed in WAXD in the presence of carbon black, and it contributed to the tensile properties. In order to understand the performances of filled NR vulcanizates, it surely is necessary to know the structural states of the mixed nano-filler and the crystallites produced upon elongation.

  10. Sustainable thermoplastic elastomers derived from cellulose, fatty acid and furfural via ATRP and click chemistry.

    PubMed

    Yu, Juan; Lu, Chuanwei; Wang, Chunpeng; Wang, Jifu; Fan, Yimin; Chu, Fuxiang

    2017-11-15

    Cellulose-based thermoplastic elastomers (TPEs) have attracted considerable attention because of their rigid backbone, good mechanical properties, renewable nature and abundance. In the present study, sustainable TPEs based on ethyl cellulose (EC), fatty acid and furfural were generated by the combination of ATRP and "click chemistry". To fabricate sustainable TPEs with higher toughness, a range of polymers, including mono random-copolymer poly(tetrahydrofurfuryl methacrylate-co-lauryl methacrylate) (P(THFMA-co-LMA), dual polymer side chains PTHFMA and PLMA, and mono-block copolymer PTHFMA-b-PLMA, were designed as side chains to fabricate EC brush copolymers with random, dual or block side chain architectures using the "grafting from" and "grafting onto" methods. The multi-armed structures, chemical compositions and phase separation of these EC brush copolymers were confirmed by FT-IR, (1)H NMR, GPC, DSC, TEM and SEM. Overall, three types of EC brush copolymers all exhibited the desired mechanical properties of TPEs. In addition, the EC brush copolymers with dual/block side chain architectures showed higher tensile strength than that of the random polymers with similar compositions. Copyright © 2017. Published by Elsevier Ltd.

  11. The reclaiming of butyl rubber and in-situ compatibilization of thermoplastic elastomer by power ultrasound

    NASA Astrophysics Data System (ADS)

    Feng, Wenlai

    This is a study of the continuous ultrasound aided extrusion process for the in-situ compatibilization of isotactic polypropylene (iPP)/ethylene-propylene diene rubber (EPDM) thermoplastic elastomer (TPE) using a newly developed ultrasonic treatment reactor. The rheological, mechanical properties and morphology of the TPE with and without ultrasonic treatment were studied. In-situ compatibilization in the ultrasonically treated blends was observed as evident by their more stable morphology after annealing, improved mechanical properties and IR spectra. The obtained results indicated that ultrasonic treatment induced the thermo-mechanical degradations and led to the possibility of enhanced molecular transport and chemical reactions at the interfaces. Processing conditions were established for enhanced in situ compatibilization of the PP/EPDM TPE. The ultrasonic treatments of butyl rubber gum and ultrasonic devulcanization of butyl rubber, tire-curing bladder during extrusion using a grooved barrel ultrasonic reactor were carried out. The ultrasonic treatment of gum caused degradation of the polymer main chain leading to lower molecular weight, broader molecular weight distribution, less unsaturation and changes in physical properties. The devulcanization of butyl rubber was successfully accomplished only at severe conditions of ultrasonic treatment. The mechanical properties of vulcanizates prepared from devulcanized butyl rubber are comparable to that of the virgin vulcanizate. The molecular characterization of sol fraction of devulcanized butyl rubber showed the devulcanization and degradation of butyl rubber occurred simultaneously. 1H NMR transverse relaxation was also used to study butyl rubber gum before and after ultrasonic treatment, and ultrasonically devulcanized unfilled butyl rubber. The T2 relaxation decays were successfully described using a two-component model. The recyclability of tire-curing bladder was also investigated. Gel fraction, crosslink

  12. Bicomponent Block Copolymers Derived from One or More Random Copolymers as an Alternative Route to Controllable Phase Behavior.

    PubMed

    Ashraf, Arman R; Ryan, Justin J; Satkowski, Michael M; Lee, Byeongdu; Smith, Steven D; Spontak, Richard J

    2017-09-01

    Block copolymers have been extensively studied due to their ability to spontaneously self-organize into a wide variety of morphologies that are valuable in energy-, medical-, and conservation-related (nano)technologies. While the phase behavior of bicomponent diblock and triblock copolymers is conventionally governed by temperature and individual block masses, it is demonstrated here that their phase behavior can alternatively be controlled through the use of blocks with random monomer sequencing. Block random copolymers (BRCs), i.e., diblock copolymers wherein one or both blocks are a random copolymer comprised of A and B repeat units, have been synthesized, and their phase behavior, expressed in terms of the order-disorder transition (ODT), has been investigated. The results establish that, depending on the block composition contrast and molecular weight, BRCs can microphase-separate. We also report that large variation in incompatibility can be generated at relatively constant molecular weight and temperature with these new soft materials. This sequence-controlled synthetic strategy is extended to thermoplastic elastomeric triblock copolymers differing in chemistry and possessing a random-copolymer midblock. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Hemocompatibility of styrenic block copolymers for use in prosthetic heart valves.

    PubMed

    Brubert, Jacob; Krajewski, Stefanie; Wendel, Hans Peter; Nair, Sukumaran; Stasiak, Joanna; Moggridge, Geoff D

    2016-02-01

    Certain styrenic thermoplastic block copolymer elastomers can be processed to exhibit anisotropic mechanical properties which may be desirable for imitating biological tissues. The ex-vivo hemocompatibility of four triblock (hard-soft-hard) copolymers with polystyrene hard blocks and polyethylene, polypropylene, polyisoprene, polybutadiene or polyisobutylene soft blocks are tested using the modified Chandler loop method using fresh human blood and direct contact cell proliferation of fibroblasts upon the materials. The hemocompatibility and durability performance of a heparin coating is also evaluated. Measures of platelet and coagulation cascade activation indicate that the test materials are superior to polyester but inferior to expanded polytetrafluoroethylene and bovine pericardium reference materials. Against inflammatory measures the test materials are superior to polyester and bovine pericardium. The addition of a heparin coating results in reduced protein adsorption and ex-vivo hemocompatibility performance superior to all reference materials, in all measures. The tested styrenic thermoplastic block copolymers demonstrate adequate performance for blood contacting applications.

  14. Aminosilane layers on the plasma activated thermoplastics: influence of solvent on its structure and morphology.

    PubMed

    Sunkara, Vijaya; Cho, Yoon-Kyoung

    2013-12-01

    The chemistry and the structure of aminosilane layer on the plasma activated thermoplastic substrates, e.g., polycarbonate (PC), polystyrene (PS), poly(methyl methacrylate) (PMMA), and cyclic olefin co-polymer (COC) were investigated at the molecular level. The nature of the surface functional groups of the silane layers prepared by solution phase deposition in aqueous and anhydrous solvents were studied using various techniques including ellipsometry, goniometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance infrared spectroscopy (ATR-IR). The XPS analyses revealed the presence of various oxygen functionalities on the plasma activated thermoplastics. Considerable differences were observed for the structure of aminosilane depending on the solvent used for the reaction. Deposition from aqueous solution resulted in relatively flat and smooth surfaces with consistent thickness compared to the anhydrous solution deposition. In the former case, 33% of the total nitrogen accounted for protonated amine and 16% for the free amino groups. In the latter, only 6% accounted for the protonated amine. The point of zero charge (pzc), on the aminosilane modified PC was found to be around 7, indicated that the surface is positively charged below pH 7 and negatively charged above pH 7. The surface analysis data suggested that various interactions are possible between the plasma activated thermoplastic surface and the aminosilane. In general, they are bound to the surface through covalent bond formation between the oxygen functionalities on the thermoplastic surface and the amino or the silanol groups of the aminosilane.

  15. Chemical-Assisted Bonding of Thermoplastics/Elastomer for Fabricating Microfluidic Valves

    PubMed Central

    Gu, Pan; Liu, Ke; Chen, Hong; Nishida, Toshikazu; Fan, Z. Hugh

    2010-01-01

    Thermoplastics such as cyclic olefin copolymer (COC) and polymethylmethacrylate (PMMA) have been increasingly used in fabricating microfluidic devices. However, the state-of-the-art microvalve technology is a polydimethylsiloxane (PDMS)-based three-layer structure. In order to integrate such a valve with a thermoplastics-based microfluidic device, a bonding method for thermoplastics/PDMS must be developed. We report here a method to bond COC with PDMS through surface activation by corona discharge, surface modification using 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), and thermal annealing. The method is also applicable to PMMA. The bonding strength between thermoplastics and PDMS was represented by the peeling force, which was measured using a method established by the International Organization for Standardization (ISO). The bonding strength measurement offered an objective and quantitative indicator for protocol optimization, as well as comparison with other PDMS-associated bonding methods. Using optimized bonding conditions, two valve arrays were fabricated in a COC/PDMS/COC device and cyclic operations of valve closing/opening were successfully demonstrated. The valve-containing devices withstood 100 psi (~689 KPa) without delamination. Further, we integrated such valve arrays in a device for protein separation and demonstrated isoelectric focusing in the presence of valves. PMID:21121689

  16. [Mechanical properties of thermoplastic materials].

    PubMed

    Zhang, Ning; Bai, Yu-xing; Zhang, Kun-ya

    2010-09-14

    To investigate the mechanical properties of various brands of thermoplastic materials under different test conditions so as to analyze their influencing factors so as to provide a reference for improving the effect of invisible orthodontics. Three brands of thermoplastic materials, DR, Biolon and Erkodent, were selected. They were tested by Instron testing machine to measure their maximal stress and modulus under different processing modes, including pre-thermoforming, post-thermoforming and dipped in artificial saliva for two weeks after thermoforming. The data were analyzed by SPSS 11.5. Analyzed the mechanical properties change-trend under each test condition. The modulus (MPa) and maximum stress (MPa) of control group were significantly higher than those of thermoforming group (DR: 9.63±0.68 vs 7.85±0.61, 267±8 vs 199±6; Erkodent: 8.28±0.28 vs 7.59±0.45, 226±6 vs 199±6; Biolon: 8.85±0.41 vs 7.07±0.22, 237±6 vs 169±7, all P<0.05). The modulus (MPa) and maximum stress (MPa) of thermoforming group were significantly lower than those of saliva immersion group (DR: 7.85±0.61 vs 9.14±0.41, 199±6 vs 243±7; Erkodent: 7.59 ± 0.45 vs 8.38±0.29, 199±6 vs 212±7; Biolon: 7.07±0.22 vs 7.90±0.31, 169±7 vs 197±5, all P<0.05). The different brands of thermoplastic materials have different mechanical properties. The different processing modes influence the mechanical properties of thermoplastic materials. The mechanical properties decrease after thermoforming and increase after saliva immersion.

  17. Diamond turning of thermoplastic polymers

    SciTech Connect

    Smith, E.; Scattergood, R.O.

    1988-12-01

    Single point diamond turning studies were made using a series of thermoplastic polymers with different glass transition temperatures. Variations in surface morphology and surface roughness were observed as a function of cutting speed. Lower glass transition temperatures facilitate smoother surface cuts and better surface finish. This can be attributed to the frictional heating that occurs during machining. Because of the very low glass transition temperatures in polymeric compared to inorganic glasses, the precision machining response can be very speed sensitive.

  18. Electrostatic prepregging of thermoplastic matrices

    NASA Technical Reports Server (NTRS)

    Muzzy, John D.; Varughese, Babu; Thammongkol, Vivan; Tincher, Wayne

    1989-01-01

    Thermoplastic towpregs of PEEK/AS-4, PEEK/S-2 glass and LaRC-TPI/AS-4, produced by electrostatic deposition of charged and fluidized polymer powders on spread continuous fiber tows, are described. Processing parameters for combining PEEK 150 powder with unsized 3k AS-4 carbon fiber are presented. The experimental results for PEEK 150/AS-4 reveal that electrostatic fluidized bed coating may be an economically attractive process for producing towpreg.

  19. Single-use thermoplastic microfluidic burst valves enabling on-chip reagent storage.

    PubMed

    Rahmanian, Omid D; DeVoe, Don L

    2015-05-01

    A simple and reliable method for fabricating single-use normally closed burst valves in thermoplastic microfluidic devices is presented, using a process flow that is readily integrated into established workflows for the fabrication of thermoplastic microfluidics. An experimental study of valve performance reveals the relationships between valve geometry and burst pressure. The technology is demonstrated in a device employing multiple valves engineered to actuate at different inlet pressures that can be generated using integrated screw pumps. On-chip storage and reconstitution of fluorescein salt sealed within defined reagent chambers are demonstrated. By taking advantage of the low gas and water permeability of cyclic olefin copolymer, the robust burst valves allow on-chip hermetic storage of reagents, making the technology well suited for the development of integrated and disposable assays for use at the point of care.

  20. Rheology of Hyperbranched Poly(triglyceride)-Based Thermoplastic Elastomers via RAFT polymerization

    NASA Astrophysics Data System (ADS)

    Yan, Mengguo; Cochran, Eric

    2014-03-01

    In this contribution we discuss how melt- and solid-state properties are influenced by the degree of branching and molecular weight in a family of hyperbranched thermoplastics derived from soybean oil. Acrylated epoxidized triglycerides from soybean oils have been polymerized to hyperbranched thermoplastic elastomers using reversible addition-fragmentation chain transfer (RAFT) polymerization. With the proper choice of chain transfer agent, both homopolymer and block copolymer can be synthesized. By changing the number of acrylic groups per triglycerides, the chain architectures can range from nearly linear to highly branched. We show how the fundamental viscoelastic properties (e.g. entanglement molecular weight, plateau modulus, etc.) are influenced by chain architecture and molecular weight.

  1. Single-use thermoplastic microfluidic burst valves enabling on-chip reagent storage

    PubMed Central

    Rahmanian, Omid D.

    2014-01-01

    A simple and reliable method for fabricating single-use normally closed burst valves in thermoplastic microfluidic devices is presented, using a process flow that is readily integrated into established workflows for the fabrication of thermoplastic microfluidics. An experimental study of valve performance reveals the relationships between valve geometry and burst pressure. The technology is demonstrated in a device employing multiple valves engineered to actuate at different inlet pressures that can be generated using integrated screw pumps. On-chip storage and reconstitution of fluorescein salt sealed within defined reagent chambers are demonstrated. By taking advantage of the low gas and water permeability of cyclic olefin copolymer, the robust burst valves allow on-chip hermetic storage of reagents, making the technology well suited for the development of integrated and disposable assays for use at the point of care. PMID:25972774

  2. Rapid, controllable and environmentally benign fabrication of thermoplastic nanofibers and applications

    NASA Astrophysics Data System (ADS)

    Wang, Dong

    In situ fibrillar and lamellar hybrid morphology was found in various immiscible polymer blends prepared by melt ram extrusion of cellulose acetate butyrate (CAB)/Thermoplastics at a weight ratio of 80 to 20. The formation process was analyzed and proposed. The presence of the elongational flow field determines the formation of the fibrils, and the improvement of the mixing efficiency can significantly reduce the dimensions of formed fibrils into the submicro- or nano-scale. With above results, continuous and uniform yarns of thermoplastic nanofibers were prepared via direct melt twin-screw extrusion, providing better mixing efficiency of immiscible blends of thermoplastic polymers with cellulose acetate butyrate (CAB), and subsequent extraction removal of CAB matrix. The thermoplastics which can be made into nanofibers include polyesters, polyolefins, thermoplastic polyurethane and functional copolymers, such as PE-co-GMA (Poly(Ethylene-co-Glycidyl Methacrylate)), PVA-co-PE (Poly(Vinyl Alcohol-co-Ethylene)). Ratios of thermoplastics to sacrificial CAB matrix, melt viscosity, and interfacial tensions affect formation of the nanofibers. Moreover, the crystal structures of isotactic polypropylene (iPP) nanofiber prepared were characterized with DSC and WAXD. To further demonstrate the size and shape controllability of the thermoplastic nanomaterials, polyethylene materials were selected and prepared into micro- or submicrospheres or nanofibers with different diameters and shapes by varying the composition ratio and modifying the interface properties via melt blending or extrusion of cellulose acetate butyrate (CAB)/LDPE melt blends and subsequent removal of the CAB. The surface structures of the LDPE micro- or submicrospheres and nanofibers were analyzed using SEM, FTIR-ATR spectroscopy, DSC and torque rheometer. The biotechnological applications of the thermoplastic nanofibers are also exploited. Poly(ethylene-co-glycidyl methacrylate) (PE-co-GMA) nanofibers with

  3. Bond strength of a chairside autopolymerizing reline resin to injection-molded thermoplastic denture base resins.

    PubMed

    Hamanaka, Ippei; Shimizu, Hiroshi; Takahashi, Yutaka

    2017-01-01

    This study evaluated the shear bond strength of a chairside autopolymerizing reline resin to injection-molded thermoplastic denture base resins. Four kinds of injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) and PMMA, as a control, were tested. The eight types of surface treatment: ((1) no treatment, (2) air abrasion, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) air abrasion and 4-META/MMA-TBB resin, (7) tribochemical silica coating, and (8) tribochemical silica coating and 4-META/MMA-TBB resin) were applied to each specimen. The chairside autopolymerizing reline resins were bonded to disks of the injection-molded thermoplastic denture base resins. All of the specimens were immersed in water for 4 months and then thermocycled for 10,000 cycles in water between 5 and 55°C. The shear bond strengths were determined. The shear bond strengths of the two polyamides treated using air abrasion, dichloromethane and ethyl acetate and no treatment were exceedingly low. The greatest bond strength was recorded for the polyethylene terephthalate copolymer specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (22.5MPa). The bond strengths of the other injection-molded thermoplastic denture base resins increased using 4-META/MMA-TBB resin. Tribochemical silica coating and 4-META/MMA-TBB resin were the most effective surface treatments among all denture base resins tested. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  4. An overview of long fiber reinforced thermoplastics

    SciTech Connect

    Bockstedt, R.J.; Skarlupka, R.J.

    1995-12-01

    Long fiber reinforced thermoplastics (LFRTP) are a class of injection molding materials that extend the physical property envelope of thermoplastics polymers. These materials are manufactured by pulling continuous fiber tows through a thermoplastic polymer melt in a specialized processing die. The strands are subsequently cooled and chopped into pellets of equal length. LFRTP materials are available in virtually every common thermoplastic resin with glass, aramid, stainless steel, or carbon fiber reinforcement at levels up to 60% by weight. Unlike short fiber reinforced thermoplastics manufactured by conventional screw compounding processes, LFRTP exhibit simultaneous improvements in both flexural modulus and impact resistance. Improvements in load transfer, creep resistance at elevated temperatures, and dimensional stability can also be attributed to the long fiber network formed in the molded part. This unique combination of properties makes LFRTP the material of choice for replacement of metal structural assemblies in many automotive, industrial, consumer and recreational applications.

  5. Thermoplastic polymides and composites therefrom

    NASA Technical Reports Server (NTRS)

    Harris, Frank W. (Inventor)

    1994-01-01

    A new class polyimide and polyimide precursors based on diaryl oxyalkylene diamines, such as 1,3-bis[4-aminophenoxy]-2,2-dimethyl propane, a process for their preparation and their use as the continuous phase for the manufacture of composites and composite laminates reinforced by reinforcing agents such as carbon fibers, Kevlar.TM., and other similar high strength reinforcing agents. The polyimides and molecular composites obtained from the diamines according to the invention show thermoplastic properties, excellent flex fatigue and fracture resistance, and excellent thermal and oxidative stability.

  6. Thermoplastic coating of carbon fibers

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Lickfield, G. C.; Drews, M. J.; Ellison, M. S.; Allen, L. E.; Mccollum, J. R.; Thomas, H. L.

    1988-01-01

    Now that quantities of prepreg were made on the thermoplastic coating line, they are being formed into both textile preform structures and directly into composite samples. The textile preforms include both woven and knitted structures which will be thermoformed into a finished part. In order to determine if the matrix resin is properly adhering to the fibers or if voids are being formed in the coating process, the tensile strength and modulus of these samples will be tested. The matrix uniformity of matrix distribution in these samples is also being determined using an image analyzer.

  7. Block and Graft Copolymers of Polyhydroxyalkanoates

    NASA Astrophysics Data System (ADS)

    Marchessault, Robert H.; Ravenelle, François; Kawada, Jumpei

    2004-03-01

    Polyhydroxyalkanoates (PHAs) were modified for diblock copolymer and graft polymer by catalyzed transesterification in the melt and by chemical synthesis to extend the side chains of the PHAs, and the polymers were studied by transmission electron microscopy (TEM) X-ray diffraction, thermal analysis and nuclear magnetic resonance (NMR). Catalyzed transesterification in the melt is used to produce diblock copolymers of poly[3-hydroxybutyrate] (PHB) and monomethoxy poly[ethylene glycol] (mPEG) in a one-step process. The resulting diblock copolymers are amphiphilic and self-assemble into sterically stabilized colloidal suspensions of PHB crystalline lamellae. Graft polymer was synthesized in a two-step chemical synthesis from biosynthesized poly[3-hydroxyoctanoate-co-3-hydroxyundecenoate] (PHOU) containing ca. 25 mol chains. 11-mercaptoundecanoic acid reacts with the side chain alkenes of PHOU by the radical addition creating thioether linkage with terminal carboxyl functionalities. The latter groups were subsequently transformed into the amide or ester linkage by tridecylamine or octadecanol, respectively, producing new graft polymers. The polymers have different physical properties than poly[3-hydroxyoctanoate] (PHO) which is the main component of the PHOU, such as non-stickiness and higher thermal stability. The combination of biosynthesis and chemical synthesis produces a hybrid thermoplastic elastomer with partial biodegradability.

  8. Thermoplastic film prevents proppant flowback

    SciTech Connect

    Nguyen, P.D.; Weaver, J.D.; Parker, M.A.; King, D.G.

    1996-02-05

    Thermoplastic film added to proppants is effective and economical for preventing proppant flowback after an hydraulic fracturing treatment. Most other methods, such as resin-coated proppant and fiber, for controlling proppant flowback have drawbacks that added to treatment costs by requiring long downtime, costly additives, or frequent equipment replacement. Thermoplastic film does not react chemically with fracturing fluids. After the proppant is placed in the fracture, the film strips intertwine with the proppant grains or at higher temperatures, the strips become adhesive and shrink forming consolidated clusters that hold open the newly created fractures and prevent proppant from flowing back. The low cost of the film means that the strips can be used throughout the fracturing job or in selected stages. The strips are compatible with fracturing fluid chemistry, including breakers and crosslinkers, and can be used in wells with a wide range of bottom hole temperatures. The end result is a well that can be brought back on-line in a short time with little proppant flowback. This paper reviews the cost benefits and performance of these proppants.

  9. Thermoplastic coating of carbon fibers

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Lickfield, G. C.; Allen, L. E.; Mccollum, J. R.

    1989-01-01

    A continuous powder coating system was developed for coating carbon fiber with LaRC-TPI (Langley Research Center-Thermoplastic Polyimide), a high-temperature thermoplastic polymide invented by NASA-Langley. The coating line developed used a pneumatic fiber spreader to separate the individual fibers. The polymer was applied within a recirculating powder coating chamber then melted using a combination of direct electrical resistance and convective heating to make it adhere to the fiber tow. The tension and speed of the line were controlled with a dancer arm and an electrically driven fiber wind-up and wind-off. The effects of heating during the coating process on the flexibility of the prepreg produced were investigated. The uniformity with which the fiber tow could be coated with polymer also was examined. Composite specimens were fabricated from the prepreg and tested to determine optimum process conditions. The study showed that a very uniform and flexible prepeg with up to 50 percent by volume polymer could be produced with this powder coating system. The coating line minimized powder loss and produced prepeg in lengths of up to 300 m. The fiber spreading was found to have a major effect on the coating uniformity and flexibility. Though test results showed low composite tensile strengths, analysis of fracture surfaces under scanning electron microscope indicated that fiber/matrix adhesion was adequate.

  10. Joining of thermoplastic substrates by microwaves

    DOEpatents

    Paulauskas, Felix L.; Meek, Thomas T.

    1997-01-01

    A method for joining two or more items having surfaces of thermoplastic material includes the steps of depositing an electrically-conductive material upon the thermoplastic surface of at least one of the items, and then placing the other of the two items adjacent the one item so that the deposited material is in intimate contact with the surfaces of both the one and the other items. The deposited material and the thermoplastic surfaces contacted thereby are then exposed to microwave radiation so that the thermoplastic surfaces in contact with the deposited material melt, and then pressure is applied to the two items so that the melted thermoplastic surfaces fuse to one another. Upon discontinuance of the exposure to the microwave energy, and after permitting the thermoplastic surfaces to cool from the melted condition, the two items are joined together by the fused thermoplastic surfaces. The deposited material has a thickness which is preferably no greater than a skin depth, .delta..sub.s, which is related to the frequency of the microwave radiation and characteristics of the deposited material in accordance with an equation.

  11. Consolidation modelling for thermoplastic composites forming simulation

    NASA Astrophysics Data System (ADS)

    Xiong, H.; Rusanov, A.; Hamila, N.; Boisse, P.

    2016-10-01

    Pre-impregnated thermoplastic composites are widely used in the aerospace industry for their excellent mechanical properties, Thermoforming thermoplastic prepregs is a fast manufacturing process, the automotive industry has shown increasing interest in this manufacturing processes, in which the reconsolidation is an essential stage. The model of intimate contact is investigated as the consolidation model, compression experiments have been launched to identify the material parameters, several numerical tests show the influents of the temperature and pressure applied during processing. Finally, a new solid-shell prismatic element has been presented for the simulation of consolidation step in the thermoplastic composites forming process.

  12. Nonlinear rheology and strain recovery of short chain branched polyolefin elastomers and thermoplastic olefin blends

    NASA Astrophysics Data System (ADS)

    Patham, Bhaskar

    Polyolefin elastomers are random copolymers having a polyethylene backbone with the higher olefinic comonomer incorporated as short-chain branches. These random copolymers are widely used as polymer modifiers for thermoplastic materials such as polypropylenes, resulting in thermoplastic olefin (TPO) blends. This thesis addresses the nonlinear rheological behavior of the elastomers and then of the TPO blends. The effects of varying short chain branch density (SCB) on the melt rheology of three ethylene-octene random copolymers have been investigated. In particular, the strain-hardening behavior in extensional flow and strain recovery following nonlinear shear creep has been evaluated. The zero-shear viscosity followed trends in the backbone molecular weight closely. While the three copolymers were indistinguishable in linear viscoelastic creep and recovery, recovery following nonlinear shear creep decreased progressively with increasing SCB density. This reveals that the extent of rapid chain equilibration that occurs over Rouse time scales at higher strains was progressively lower with increasing SCB density. Strain hardening in uniaxial extensional flow was observed for all three copolymers. At strain rates below the primitive chain equilibration rates, strain hardening increases progressively with increasing SCB density. At higher rates, upon onset of primitive chain stretch, the strain hardening behavior for the three melts merges. Two thermoplastic olefin (TPO) blends were characterized in the context of injection molding; the surface morphology of injection molded tensile bars with these materials showed surface defects or flow marks to different extents. The flow marks were traced to different degrees of strain recovery in the dispersed phases of the two blends. This recovery occurred over injection molding timescales of the order of a few seconds. Strain recovery after shear creep was higher in the blend that displayed more severe flow marks in injection

  13. Phase separations in a copolymer copolymer mixture

    NASA Astrophysics Data System (ADS)

    Zhang, Jin-Jun; Jin, Guojun; Ma, Yuqiang

    2006-01-01

    We propose a three-order-parameter model to study the phase separations in a diblock copolymer-diblock copolymer mixture. The cell dynamical simulations provide rich information about the phase evolution and structural formation, especially the appearance of onion-rings. The parametric dependence and physical reason for the domain growth of onion-rings are discussed.

  14. Plastic wastes as modifiers of the thermoplasticity of coal

    SciTech Connect

    M.A. Diez; C. Barriocanal; R. Alvarez

    2005-12-01

    Plastic waste recycling represents a major challenge in environmental protection with different routes now available for dealing with mechanical, chemical, and energy recycling. New concepts in plastic waste recycling have emerged so that now such wastes can be used to replace fossil fuels, either as an energy source or as a secondary raw material. Our objective is to explore the modification of the thermoplastic properties of coal in order to assess the possibility of adding plastic waste to coal for the production of metallurgical coke. Two bituminous coals of different rank and thermoplastic properties were used as a base component of blends with plastic wastes such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), poly(ethylene terephthalate) (PET), and acrilonitrile-butadiene-styrene copolymer (ABS). In all cases, the addition of plastic waste led to a reduction in Gieseler maximum fluidity, the extent of the reduction depending on the fluidity of the base coal, and the amount, the molecular structure, and the thermal behavior of the polymer. As a consequence, the amount of volatile matter released by the plastic waste before, during, and after the maximum fluidity of the coal and the hydrogen-donor and hydrogen-acceptor capacities of the polymer were concluded to be key factors in influencing the extent of the reduction in fluidity and the development of anisotropic carbons. The incorporation of the plastic to the carbon matrix was clearly established in semicokes produced from blends of a high-fluid coal and the plastic tested by SEM examination. 42 refs., 10 figs., 7 tabs.

  15. Synthesis and Structure - Property Relationships for Regular Multigraft Copolymers

    SciTech Connect

    Mays, Jimmy; Uhrig, David; Gido, Samuel; Zhu, Yuqing; Weidisch, Roland; Iatrou, Hermis; Hadjichristidis, Nikos; Hong, Kunlun; Beyer, Frederick; Lach, Ralph

    2004-01-01

    Multigraft copolymers with polyisoprene backbones and polystyrene branches, having multiple regularly spaced branch points, were synthesized by anionic polymerization high vacuum techniques and controlled chlorosilane linking chemistry. The functionality of the branch points (1, 2 and 4) can be controlled, through the choice of chlorosilane linking agent. The morphologies of the various graft copolymers were investigated by transmission electron microscopy and X-ray scattering. It was concluded that the morphology of these complex architectures is governed by the behavior of the corresponding miktoarm star copolymer associated with each branch point (constituting block copolymer), which follows Milner's theoretical treatment for miktoarm stars. By comparing samples having the same molecular weight backbone and branches but different number of branches it was found that the extent of long range order decreases with increasing number of branch points. The stress-strain properties in tension were investigated for some of these multigraft copolymers. For certain compositions thermoplastic elastomer (TPE) behavior was observed, and in many instances the elongation at break was much higher (2-3X) than that of conventional triblock TPEs.

  16. Thermoplastic-carbon fiber hybrid yarn

    NASA Technical Reports Server (NTRS)

    Ketterer, M. E.

    1984-01-01

    Efforts were directed to develop processing methods to make carbon fiber/thermoplastic fiber preforms that are easy to handle and drapeable, and to consolidate them into low void content laminates. The objectives were attained with the development of the hybrid yarn concept; whereby, thermoplastic fiber can be intimately intermixed with carbon fiber into a hybrid yarn. This was demonstrated with the intermixing of Celion 3000 with a Celanese liquid crystal polymer fiber, polybutylene terepthalate fiber, or polyetheretherketone fiber. The intermixing of the thermoplastic matrix fiber and the reinforcing carbon fiber gives a preform that can be easily fabricated into laminates with low void content. Mechanical properties of the laminates were not optimized; however, initial results indicated properties typical of a thermoplastic/carbon fiber composites prepared by more conventional methods.

  17. Thermoplastic matrix composite processing model

    NASA Technical Reports Server (NTRS)

    Dara, P. H.; Loos, A. C.

    1985-01-01

    The effects the processing parameters pressure, temperature, and time have on the quality of continuous graphite fiber reinforced thermoplastic matrix composites were quantitatively accessed by defining the extent to which intimate contact and bond formation has occurred at successive ply interfaces. Two models are presented predicting the extents to which the ply interfaces have achieved intimate contact and cohesive strength. The models are based on experimental observation of compression molded laminates and neat resin conditions, respectively. Identified as the mechanism explaining the phenomenon by which the plies bond to themselves is the theory of autohesion (or self diffusion). Theoretical predictions from the Reptation Theory between autohesive strength and contact time are used to explain the effects of the processing parameters on the observed experimental strengths. The application of a time-temperature relationship for autohesive strength predictions is evaluated. A viscoelastic compression molding model of a tow was developed to explain the phenomenon by which the prepreg ply interfaces develop intimate contact.

  18. Tough, High-Performance, Thermoplastic Addition Polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H.; Proctor, K. Mason; Gleason, John; Morgan, Cassandra; Partos, Richard

    1991-01-01

    Series of addition-type thermoplastics (ATT's) exhibit useful properties. Because of their addition curing and linear structure, ATT polymers have toughness, like thermoplastics, and easily processed, like thermosets. Work undertaken to develop chemical reaction forming stable aromatic rings in backbone of ATT polymer, combining high-temperature performance and thermo-oxidative stability with toughness and easy processibility, and minimizing or eliminating necessity for tradeoffs among properties often observed in conventional polymer syntheses.

  19. Multi angle laser light scattering evaluation of field exposed thermoplastic photovoltaic encapsulant materials

    DOE PAGES

    Kempe, Michael D.; Miller, David C.; Wohlgemuth, John H.; ...

    2016-01-08

    As creep of polymeric materials is potentially a safety concern for photovoltaic modules, the potential for module creep has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. To investigate the possibility of creep, modules were constructed, using several thermoplastic encapsulant materials, into thin-film mock modules and deployed in Mesa, Arizona. The materials examined included poly(ethylene)-co-vinyl acetate (EVA, including formulations both cross-linked and with no curing agent), polyethylene/polyoctene copolymer (PO), poly(dimethylsiloxane) (PDMS), polyvinyl butyral (PVB), and thermoplastic polyurethane (TPU). The absence of creep in this experiment is attributable to several factors of which themore » most notable one was the unexpected cross-linking of an EVA formulation without a cross-linking agent. It was also found that some materials experienced both chain scission and cross-linking reactions, sometimes with a significant dependence on location within a module. The TPU and EVA samples were found to degrade with cross-linking reactions dominating over chain scission. In contrast, the PO materials degraded with chain scission dominating over cross-linking reactions. Furthermore, we found no significant indications that viscous creep is likely to occur in fielded modules capable of passing the qualification tests, we note that one should consider how a polymer degrades, chain scission or cross-linking, in assessing the suitability of a thermoplastic polymer in terrestrial photovoltaic applications.« less

  20. Precision synthesis of bio-based acrylic thermoplastic elastomer by RAFT polymerization of itaconic acid derivatives.

    PubMed

    Satoh, Kotaro; Lee, Dong-Hyung; Nagai, Kanji; Kamigaito, Masami

    2014-01-01

    Bio-based polymer materials from renewable resources have recently become a growing research focus. Herein, a novel thermoplastic elastomer is developed via controlled/living radical polymerization of plant-derived itaconic acid derivatives, which are some of the most abundant renewable acrylic monomers obtained via the fermentation of starch. The reversible addition-fragmentation chain-transfer (RAFT) polymerizations of itaconic acid imides, such as N-phenylitaconimide and N-(p-tolyl)itaconimide, and itaconic acid esters, such as di-n-butyl itaconate and bis(2-ethylhexyl) itaconate, are examined using a series of RAFT agents to afford well-defined polymers. The number-average molecular weights of these polymers increase with the monomer conversion while retaining relatively narrow molecular weight distributions. Based on the successful controlled/living polymerization, sequential block copolymerization is subsequently investigated using mono- and di-functional RAFT agents to produce block copolymers with soft poly(itaconate) and hard poly(itaconimide) segments. The properties of the obtained triblock copolymer are evaluated as bio-based acrylic thermoplastic elastomers. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Polyaryl ethers and related polysiloxane copolymer molecular coatings preparation and radiation degrdation

    NASA Technical Reports Server (NTRS)

    Mcgrath, J. E.; Hedrick, J. L.; Webster, D. C.; Johnson, B. C.; Mohanty, D. K.; Yilgor, I.

    1983-01-01

    Poly(arylene ether sulfones) comprise a class of materials known as engineering thermoplastics which have a variety of important applications. These polymers are tough, rigid materials with good mechanical properties over a wide temperature range, and they are processed by conventional methods into products typically having excellent hydrolytic, thermal, oxidative and dimensional stability. Wholly aromatic random copolymers of hydroquinone and biphenol with 4.4 prime dichlorodiphenyl sulfone were synthesized via mechanical nucleophilic displacement. Their structures were characterized and mechanical behavior studied. These tough, ductile copolymers show excellent radiation resistance to electron beam treatment and retain much of the mechanical properties up to at least 700 Mrads under argon.

  2. Dynamic viscoelasticities for short fiber-thermoplastic elastomer composites

    SciTech Connect

    Guo, Wuyun; Ashida, Michio . Graduate School of Science and Technology)

    1993-11-20

    Dynamic moduli, E[prime] and E[double prime], and loss tangent tan [delta] were investigated for thermoplastic elastomers (TPEs), styrene-isoprene-styrene copolymers (SISs), styrene-butadiene-styrene copolymer (SBS), and Hytrel and composites reinforced by poly(ethylene terephthalate) (PET) short fibers. The styrenic TPEs have a typical rubbery behavior and the Hytrel TPE has medial characteristics between rubber and plastic. Both E[prime] and E[double prime] of the composites depended on the matrix as well as the fiber loading and fiber length. Based on the viewpoint of different extensibility between the fiber and the matrix elastomer, a triblock model was considered for estimating the storage modulus of the short fiber-TPE composites as follows: E[sub c] = [alpha] V[sub f]E[sub f] + [beta](1 [minus] V[sub f])E[sub m], where [alpha] and [beta] are the effective deformation coefficients for the fiber and the matrix elastomer, respectively. They can be quantitatively represented by modulus ratio M (= E[sub m]/E[sub f]) and fiber length L: [alpha] = (L[sup n] + k)M/(L[sup n]M + k), [beta] = (1 [minus] [alpha]V[sub f])/(1 [minus] V[sub f]), where the constants n and k are obtained experimentally. When k = 0.0222 and n = 0.45, E[sub c] of the TPE composites agreed well with the prediction of the proposed model. The relaxation spectrum of the composites showed a distinct main peak ascribed to the matrix elastomer, but no peak to the PET fiber.

  3. Laser beam welding of thermoplastics

    NASA Astrophysics Data System (ADS)

    Russek, Ulrich A.; Palmen, A.; Staub, H.; Poehler, J.; Wenzlau, C.; Otto, G.; Poggel, M.; Koeppe, A.; Kind, H.

    2003-07-01

    Current product development showing an ever shrinking physical volume is asking for new, reliable joining technologies. Laser beam technologies conceal innovative solutions to overcome limitations of conventional joining technologies. Laser beam welding of thermoplastics offers several process technical advantages. The joining energy is fed contact-less into the joining area, avoiding mechanical stress and thermal load to the joining partners. The energy is supplied spatially (seam width on the order of 100 μm) and timely (interaction time on the order of ms) very well defined. Different process strategies are possible leading to flexibility, product adapted irradiation, short process times and high quality weld seams as well as to high integration abilities and automation potentials. During the joining process no vibration, no thermal stress, no particle release takes place. Therefore, destruction of mechanically and electronically highly sensitive components, such as microelectronics, is avoided. The work place pollution is neglectable compared to other joining technologies, such as gluing (fume) or ultrasonic welding (noise, pieces of fluff). Not only micro-components can be welded in a reproducible way but also macro-components while obtaining a hermetic sealing with good optical appearance. In this publication firstly, an overview concerning process technical basis, aspects and challenges is given. Next, results concerning laser penetration welding of polymers using high power diode lasers are presented, while comparing contour and simultaneous welding by experimental results and the on-line process monitoring.

  4. An overview of long fiber reinforced thermoplastics

    SciTech Connect

    Bockstedt R.J.; Skarlupka, R.J.

    1997-12-31

    Long fiber reinforced thermoplastics (LFRTP) are a class of injection molding materials that extend the physical property envelope of thermoplastic polymers. The technology to manufacture LFRTP has improved during the last 10 years. This has resulted in dramatic improvements in the quality of these materials. They are now used in numerous, high volume commercial applications. LFRTP are pelletized, fiber reinforced thermoplastic polymers which are injection molded to form parts. The reinforcing fibers are 9-12 mm in length, compared to 0.5-1.0 mm typically found in other fiber reinforced thermoplastic materials. These longer fibers provide several property enhancements: higher impact strength, improved modulus at elevated temperatures and better dimensional stability. LFRTP are manufactured by pulling continuous fiber tows through a thermoplastic polymer melt in a specialized processing die. The ratio of fiber to resin is controlled by a metering orifice. The resulting rods are cut into pellets, 8-12 mm in length, that can be injection molded to form a part. Early manufacturing attempts mimicked wire-coating technology and did not wet-out the individual fibers within the tow. This resulted in poorly wet-out pellets, containing high levels of loose fibers. This creates problems in automated material handling and produces potential flaws in a molded part.

  5. Microstructure and thermomechanical properties relationship of segmented thermoplastic polyurethane (TPU)

    NASA Astrophysics Data System (ADS)

    Frick, Achim; Borm, Michael; Kaoud, Nouran; Kolodziej, Jan; Neudeck, Jens

    2014-05-01

    Thermoplastic polyurethanes (TPU) are important polymeric materials for seals. In competition with Acrylonitrile butadiene rubbers (NBR), TPU exhibits higher strength and a considerable better abrasion resistance. The advantage of NBR over TPU is a smaller compression set but however TPU excels in its much shorter processing cycle times. Generally a TPU is a block copolymer composed of hard and soft segments, which plays an important role in determining the material properties. TPU can be processed either to ready moulded parts or can be incorporated by multi component moulding, in both cases it shows decent mechanical properties. In the present work, the relationship between melt-process induced TPU morphology and resultant thermo mechanical properties were examined and determined by means of quasi-static tensile test, creep experiment, tension test and dynamical mechanical analysis (DMA). Scanning electron beam microscope (SEM) and differential scanning calorimeter (DSC) were used to study the morphology of the samples. A significant mathematical description of the stress-strain behaviour of TPU was found using a 3 term approach. Moreover it became evident that processing conditions such as processing temperature have crucial influence on morphology as well as short and long-term performance. To be more precise, samples processed at higher temperatures showed a lack of large hard segment agglomerates, a smaller strength for strains up to 250% and higher creep compliance.

  6. Microstructure and thermomechanical properties relationship of segmented thermoplastic polyurethane (TPU)

    SciTech Connect

    Frick, Achim Borm, Michael Kaoud, Nouran Kolodziej, Jan Neudeck, Jens

    2014-05-15

    Thermoplastic polyurethanes (TPU) are important polymeric materials for seals. In competition with Acrylonitrile butadiene rubbers (NBR), TPU exhibits higher strength and a considerable better abrasion resistance. The advantage of NBR over TPU is a smaller compression set but however TPU excels in its much shorter processing cycle times. Generally a TPU is a block copolymer composed of hard and soft segments, which plays an important role in determining the material properties. TPU can be processed either to ready moulded parts or can be incorporated by multi component moulding, in both cases it shows decent mechanical properties. In the present work, the relationship between melt-process induced TPU morphology and resultant thermo mechanical properties were examined and determined by means of quasi-static tensile test, creep experiment, tension test and dynamical mechanical analysis (DMA). Scanning electron beam microscope (SEM) and differential scanning calorimeter (DSC) were used to study the morphology of the samples. A significant mathematical description of the stress-strain behaviour of TPU was found using a 3 term approach. Moreover it became evident that processing conditions such as processing temperature have crucial influence on morphology as well as short and long-term performance. To be more precise, samples processed at higher temperatures showed a lack of large hard segment agglomerates, a smaller strength for strains up to 250% and higher creep compliance.

  7. Analysis of ageing of amorphous thermoplastic polymers by PVT analysis

    NASA Astrophysics Data System (ADS)

    Greco, Antonio; Maffezzoli, Alfonso; Gennaro, Riccardo; Rizzo, Michele

    2012-07-01

    The aim of this work is the analysis of ageing phenomenon occurring in amorphous thermoplastic polymers below their glass transition temperature by pressure-volume-temperature (PVT) analysis. The ageing behavior of different polymers as a function of the heating and cooling rates has been widespread studied. Also, different works in literature are aimed to study the effect of the applied pressure on the glass transition behavior. Another relevant aspect related to the glass transition behavior is related to the ageing effects, which can also be influenced by the applied pressure. This is a very relevant issue, since most of the polymers, during ageing, are subjected to mechanical loading. PVT analysis was used to study the ageing of amorphous PET copolymer (PETg) at different pressure levels. Specific volume-temperature curves measured during the cooling and the heating steps were used for calculating the relaxed specific volume, showing that ageing effects increase with increasing applied pressure. The evolution of the fictive temperature as a function of time was calculated from experimental data.

  8. Protein based Block Copolymers

    PubMed Central

    Rabotyagova, Olena S.; Cebe, Peggy; Kaplan, David L.

    2011-01-01

    Advances in genetic engineering have led to the synthesis of protein-based block copolymers with control of chemistry and molecular weight, resulting in unique physical and biological properties. The benefits from incorporating peptide blocks into copolymer designs arise from the fundamental properties of proteins to adopt ordered conformations and to undergo self-assembly, providing control over structure formation at various length scales when compared to conventional block copolymers. This review covers the synthesis, structure, assembly, properties, and applications of protein-based block copolymers. PMID:21235251

  9. Semicrystalline polyamide engineering thermoplastics based on the renewable monomer, 1,9-nonane diamine: Thermal properties and water absorption

    SciTech Connect

    Kugel, Alex; He, Jie; Samanta, Satyabrata; Bahr, James; Lattimer, Jessica L.; Fuqua, Michael A.; Ulven, Chad A.; Chisholm, Bret J.

    2012-08-27

    Here, a series of poly(1,9-nonamethylene adipamide-co-1,9-nonamethylene terephthalamide) copolymers were produced using melt polymerization and the thermal properties, crystal structure, and moisture uptake characterized. The results confirmed that the copolymers exhibit isomorphism. As expected, glass transition temperature and the apparent melting temperature increased with increasing terephthalmide content. Using the difference in the apparent melting temperature to the crystallization temperature as a measure of relative crystallization rate, it was observed that crystallization rate decreased as the terephthalamide content of the copolymer was increased from 0 to 50 mole percent but then sharply increased when increased beyond 50 mole percent. This behavior may be the result of extensive inter- and intramolecular interactions in the melt associated with terephthalmide units in the polymer chain that nucleate crystallization upon cooling below the equilibrium melting temperature. Comparing the thermal properties of copolymers possessing an excess of terephthalmide units to the commodity polyamide Nylon 6,6, it is believed that these copolymers may have utility as partially renewable engineering thermoplastics.

  10. Semicrystalline polyamide engineering thermoplastics based on the renewable monomer, 1,9-nonane diamine: Thermal properties and water absorption

    DOE PAGES

    Kugel, Alex; He, Jie; Samanta, Satyabrata; ...

    2012-08-27

    Here, a series of poly(1,9-nonamethylene adipamide-co-1,9-nonamethylene terephthalamide) copolymers were produced using melt polymerization and the thermal properties, crystal structure, and moisture uptake characterized. The results confirmed that the copolymers exhibit isomorphism. As expected, glass transition temperature and the apparent melting temperature increased with increasing terephthalmide content. Using the difference in the apparent melting temperature to the crystallization temperature as a measure of relative crystallization rate, it was observed that crystallization rate decreased as the terephthalamide content of the copolymer was increased from 0 to 50 mole percent but then sharply increased when increased beyond 50 mole percent. This behavior maymore » be the result of extensive inter- and intramolecular interactions in the melt associated with terephthalmide units in the polymer chain that nucleate crystallization upon cooling below the equilibrium melting temperature. Comparing the thermal properties of copolymers possessing an excess of terephthalmide units to the commodity polyamide Nylon 6,6, it is believed that these copolymers may have utility as partially renewable engineering thermoplastics.« less

  11. Investigations into the mechanical and physical behavior of thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Wright, Kathryn Janelle

    This thesis describes investigations into the physical and mechanical characteristics of two commercial thermoplastic elastomer (TPE) systems. Both systems studied exhibit elastomeric behavior similar to more traditional crosslinked elastomers; however, in these TPEs non-conventional polymer architectures and morphologies are used to produce their elastomeric behavior. The two TPEs of interest are ethylene-propylene random copolymers and dynamically vulcanized blends of ethylene-propylene-diene monomer (EPDM) and isotactic polypropylene (iPP). Very few studies have examined the mechanical behavior of these materials in terms of their composition and morphology. As such, the primary goal of this research is to both qualitatively and quantitatively understand the influence of composition and morphology on mechanical behavior. In additional very little information is available that compares their performance with that of crosslinked elastomers. As a result, the secondary goal is to qualitatively compare the mechanical responses of these TPEs with that of their more traditional counterparts. The ethylene-propylene copolymers studied have very high comonomer contents and exhibit slow crystallization kinetics. Their morphology consists of nanoscale crystallites embedded in an amorphous rubbery matrix. These crystallites act as physical crosslinks that allow for elasticity. Slow crystallization causes subsequent changes in mechanical behavior that take place over days and even weeks. Physical responses (e.g., density, crystallization kinetics, and crystal structure) of five copolymer compositions are investigated. Mechanical responses (e.g., stiffness, ductility, yielding, and reversibility) are also examined. Finally, the influence of morphology on deformation is studied using in situ analytical techniques. The EPDM/iPP blends are dynamically vulcanized which produces a complex morphology consisting of chemically crosslinked EPDM domains embedded within a semicrystalline

  12. Thermoplastic coated carbon fibers for textile preforms

    NASA Technical Reports Server (NTRS)

    Allen, L. E.; Edie, D. D.; Lickfield, G. C.; Mccollum, J. R.

    1988-01-01

    A continuous process for producing prepreg from carbon fiber and thermoplastic matrix is described. After the tow has been spread using a pneumatic device, the process utilizes a fluidized bed to apply thermoplastic powder to the bundle. Finally, direct electrical heating of the coated fiber tow melts the polymer on the individual fibers, creating a uniform and extremely flexible prepreg. The efficiency of the process was evaluated during initial trials in which a thermoplastic polyimide, LaRC-TPI, was applied to T-300, 3K (3000 filament) carbon fiber tow. The physical properties of unidirectional composite specimens fabricated from this prepreg were measured, and the matrix uniformity and void content of the samples was determined. The results of these evaluations are detailed and discussed.

  13. Toughening Thermoplastics with Thermotropic Liquid Crystal Polymers

    NASA Astrophysics Data System (ADS)

    Wiff, Donald

    1997-03-01

    Blends of thermotropic liquid crystalline and thermoplastic polymers have improvements in mechanical properties when high elongational flow provides LC needle shaped domains. This means the test sample must be a filament. Without elongational flow the LC domains are globular in shape and provide little or no mechanical property enhancement. One solution to this problem is to make the LC domains small enough so that their size approaches that of microvoids in the thermoplastic polymer system. Such an approach can potentially provide a pseudo-compatible blend. Thus if the thermoplastic matrix polymer is transparent, the nano size LC domains can provide reinforcement, modified optical properties, and still leave the bulk material transparent. This investigation focusses on the process and improvement in mechanical and fracture resistant properties.

  14. Experimental simulation of the thermoplastic pultrusion process

    SciTech Connect

    Squires, C.; Almaraz, J.; O`Toole, B.

    1996-12-31

    An experimental procedure is being developed to simulate the thermoplastic pultrusion process. A compression molding die has been designed to produce a part with the same cross-sectional geometry as the pultrusion machine being developed. Processing variables such as heating and cooling rates, pressure profiles and fiber tension may be varied to simulate the pultrusion fabrication. Processing experiments can be conducted quickly on a relatively small amount of material. Results of the experiments may be useful in determining a range of acceptable processing cycles can be used with the theoretical thermoplastic pultrusion process models under development to design appropriate heating and cooling systems as well as an optimized die cross-section. These efforts will hopefully lead to components with acceptable mechanical properties and appearance which have been pultruded at high speed. To date, attempts at high speed thermoplastic pultrusion have met with limited success.

  15. Selecting thermoplastics for engineering applications. Second edition

    SciTech Connect

    MacDermott, C.P.; Shenoy, A.V.

    1997-12-31

    The difficult problem of selecting the best thermoplastic resin is made easier by the guidelines presented in this book. Included are methods of ranking the thermoplastics by their properties, price, and processability, along with quick-reference tables of rankings. Example programs for computerized ranking are also included. The problems of matching part design and molding conditions are also addressed. Contents include: (1) the selection process; (2) physical properties; (3) rheological properties; (4) injection molding; (5) prototype parts; (6) estimating part costs; (7) ranking of resins; (8) computerized approach to selection; (9) expert system SELECTHER; (10) resin suppliers; and (11) nomenclature and glossary.

  16. Design and manufacturing concepts for thermoplastic structures

    NASA Technical Reports Server (NTRS)

    Renieri, Michael P.; Burpo, Steven J.; Roundy, Lance M.

    1991-01-01

    Results to date on the application of two manufacturing techniques, fiber placement and single diaphragm/coconsolidation, to produce cost-effective, thermoplastic composite (TPC), primary fuselage structure are presented. Applications relative to fuselage upper cover structure indicate potential cost savings relative to conventional approaches. Progress is also presented on efforts concerned with other design details which take advantage of thermoplastic composites such as fastener less stiffener/frame attachments. In addition, results are presented on the development and verification testing of a composite lug analysis program which incorporates through-the-thickness effects.

  17. Method of forming a foamed thermoplastic polymer

    DOEpatents

    Duchane, David V.; Cash, David L.

    1986-01-01

    A method of forming a foamed thermoplastic polymer. A solid thermoplastic lymer is immersed in an immersant solution comprising a compatible carrier solvent and an infusant solution containing an incompatible liquid blowing agent for a time sufficient for the immersant solution to infuse into the polymer. The carrier solvent is then selectively extracted, preferably by a solvent exchange process in which the immersant solution is gradually diluted with and replaced by the infusant solution, so as to selectively leave behind the infusant solution permanently entrapped in the polymer. The polymer is then heated to volatilize the blowing agent and expand the polymer into a foamed state.

  18. New Polytetrahydrofuran Graft Copolymers.

    DTIC Science & Technology

    1979-03-15

    chioroprene) , chiorobutyl - ~~~~~ rubber , bromobutyl rubber , chlorinated EPDM , chlorinated poly(buta— diene) and chlorinated butadiene styrene copolymer...bromobutyl rubber , which after dehalogenation is unstable with respect to conjugated dienes, the yields of graft copolymer are low. With poly(chloroprerte

  19. Silicone/Acrylate Copolymers

    NASA Technical Reports Server (NTRS)

    Dennis, W. E.

    1982-01-01

    Two-step process forms silicone/acrylate copolymers. Resulting acrylate functional fluid is reacted with other ingredients to produce copolymer. Films of polymer were formed by simply pouring or spraying mixture and allowing solvent to evaporate. Films showed good weatherability. Durable, clear polymer films protect photovoltaic cells.

  20. Biodegradation Of thermoplastic polyurethanes from vegetable oils

    USDA-ARS?s Scientific Manuscript database

    Thermoplastic urethanes based on polyricinoleic acid soft segments and MDI/BD hard segments with varied soft segment concentration were prepared. Soft segment concentration was varied fro, 40 to 70 wt %. Biodegradation was studied by respirometry. Segmented polyurethanes with soft segments based ...

  1. Apparatus for thermoforming thermoplastic sheet materials

    SciTech Connect

    Bullock, L.W.; Kovacs, F.; Vlahek, J.

    1985-02-19

    The present invention relates to an improved plug or tool for use in the production of shaped articles from thermoplastic sheet materials. An important feature of the present invention is that the tool or plug comprises a body portion which incorporates one or more inserts which possess a thermal conductivity different from the thermal conductivity of the body portion.

  2. Thermoforming of thermoplastic matrix composites. Part I

    SciTech Connect

    Harper, R.C.

    1992-03-01

    Long-fiber-reinforced polymer matrix composites find widespread use in a variety of commercial applications requiring properties that cannot be provided by unreinforced plastics or other common materials of construction. However, thermosetting matrix resins have long been plagued by production processes that are slow and difficult to automate. This has limited the use of long-fiber-reinforced composites to relatively low productivity applications in which higher production costs can be justified. Unreinforced thermoplastics, by their very nature, can easily be made into sheet form and processed into a variety of formed shapes by various pressure assisted thermoforming means. It is possible to incorporate various types of fiber reinforcement to suit the end use of the thermoformed shape. Recently developed thermoplastic resins can also sometimes correct physical property deficiencies in a thermoset matrix composite. Many forms of thermoplastic composite material now exist that meet all the requirements of present day automotive and aerospace parts. Some of these are presently in production, while others are still in the development stage. This opens the possibility that long-fiber-reinforced thermoplastics might break the barrier that has long limited the applications for fiber-reinforced composites. 37 refs., 8 figs., 5 tabs.

  3. Ultrasonic Welding of Graphite/Thermoplastic Composite

    NASA Technical Reports Server (NTRS)

    Hardy, S. S.; Page, D. B.

    1982-01-01

    Ultrasonic welding of graphite/thermoplastic composite materials eliminates need for fasteners (which require drilling or punching, add weight, and degrade stiffness) and can be totally automated in beam fabrication and assembly jigs. Feasibility of technique has been demonstrated in laboratory tests which show that neither angular orientation nor vacuum affect weld quality.

  4. Ultrasonic Welding of Graphite/Thermoplastic Composite

    NASA Technical Reports Server (NTRS)

    Hardy, S. S.; Page, D. B.

    1982-01-01

    Ultrasonic welding of graphite/thermoplastic composite materials eliminates need for fasteners (which require drilling or punching, add weight, and degrade stiffness) and can be totally automated in beam fabrication and assembly jigs. Feasibility of technique has been demonstrated in laboratory tests which show that neither angular orientation nor vacuum affect weld quality.

  5. Modeling of a thermoplastic pultrusion process

    SciTech Connect

    Astroem, B.T. ); Pipes, R.B. )

    1991-07-01

    To obtain a fundamental understanding of the effects of processing parameters and die geometry in a pultrusion process, a mathematical model is essential in order to minimize the number of trial-and-error experiments. Previous investigators have suggested a variety of more or less complete models for thermoset pultrusion, while little effort seems to have been spent modeling its less well-understood thermoplastic equivalent. Hence, a set of intricately related models to describe the temperature and pressure distributions, as well as the matrix flow, in a thermoplastic composite as it travels through the pultrusion die is presented. An approach to calculate the accumulated pulling force is also explored, and the individual mechanisms contributing to the pulling force are discussed. The pressure model incorporates a matrix viscosity that varies with shear rate, temperature, and pressure. Comparisons are made between shear-rate-dependent and Newtonian viscosity representations, indicating the necessity of including non-Newtonian fluid behavior when modeling thermoplastic pultrusion. The governing equations of the models are stated in general terms, and simplifications are implemented in order to obtain solutions without extensive numerical efforts. Pressure, temperature, cooling rate, and pulling force distributions are presented for carbon-fiber-reinforced polyetheretherketone. Pulling force predictions are compared to data obtained from preliminary experiments conducted with a model pultrusion line that was built solely for the pultrusion of thermoplastic matrix composites, and the correlation is found to be qualitatively satisfactory.

  6. Chemicals having estrogenic activity can be released from some bisphenol A-free, hard and clear, thermoplastic resins.

    PubMed

    Bittner, George D; Denison, Michael S; Yang, Chun Z; Stoner, Matthew A; He, Guochun

    2014-12-04

    Chemicals that have estrogenic activity (EA) can potentially cause adverse health effects in mammals including humans, sometimes at low doses in fetal through juvenile stages with effects detected in adults. Polycarbonate (PC) thermoplastic resins made from bisphenol A (BPA), a chemical that has EA, are now often avoided in products used by babies. Other BPA-free thermoplastic resins, some hypothesized or advertised to be EA-free, are replacing PC resins used to make reusable hard and clear thermoplastic products such as baby bottles. We used two very sensitive and accurate in vitro assays (MCF-7 and BG1Luc human cell lines) to quantify the EA of chemicals leached into ethanol or water/saline extracts of fourteen unstressed or stressed (autoclaving, microwaving, UV radiation) thermoplastic resins. Estrogen receptor (ER)-dependent agonist responses were confirmed by their inhibition with the ER antagonist ICI 182,780. Our data showed that some (4/14) unstressed and stressed BPA-free thermoplastic resins leached chemicals having significant levels of EA, including one polystyrene (PS), and three Tritan™ resins, the latter reportedly EA-free. Exposure to UV radiation in natural sunlight resulted in an increased release of EA from Tritan™ resins. Triphenyl-phosphate (TPP), an additive used to manufacture some thermoplastic resins such as Tritan™, exhibited EA in both MCF-7 and BG1Luc assays. Ten unstressed or stressed glycol-modified polyethylene terephthalate (PETG), cyclic olefin polymer (COP) or copolymer (COC) thermoplastic resins did not release chemicals with detectable EA under any test condition. This hazard survey study assessed the release of chemicals exhibiting EA as detected by two sensitive, widely used and accepted, human cell line in vitro assays. Four PC replacement resins (Tritan™ and PS) released chemicals having EA. However, ten other PC-replacement resins did not leach chemicals having EA (EA-free-resins). These results indicate that PC

  7. Structural Color for Additive Manufacturing: 3D-Printed Photonic Crystals from Block Copolymers.

    PubMed

    Boyle, Bret M; French, Tracy A; Pearson, Ryan M; McCarthy, Blaine G; Miyake, Garret M

    2017-03-28

    The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing. The wavelength of reflected light could be tuned across the visible spectrum by synthetically controlling the block copolymer molecular weight and manufacture parts that reflected violet, green, or orange light with the capacity to serve as selective optical filters and light guides.

  8. Controlling sub-microdomain structure in microphase-ordered block copolymers and their nanocomposites

    NASA Astrophysics Data System (ADS)

    Bowman, Michelle Kathleen

    Block copolymers exhibit a wealth of morphologies that continue to find ubiquitous use in a diverse variety of mature and emergent (nano)technologies, such as photonic crystals, integrated circuits, pharmaceutical encapsulents, fuel cells and separation membranes. While numerous studies have explored the effects of molecular confinement on such copolymers, relatively few have examined the sub-microdomain structure that develops upon modification of copolymer molecular architecture or physical incorporation of nanoscale objects. This work will address two relevant topics in this vein: (i) bidisperse brushes formed by single block copolymer molecules and (ii) copolymer nanocomposites formed by addition of molecular or nanoscale additives. In the first case, an isomorphic series of asymmetric poly(styrene-b -isoprene-b-styrene) (S1IS2) triblock copolymers of systematically varied chain length has been synthesized from a parent SI diblock copolymer. Small-angle x-ray scattering, coupled with dynamic rheology and self-consistent field theory (SCFT), reveals that the progressively grown S2 block initially resides in the I-rich matrix and effectively reduces the copolymer incompatibility until a critical length is reached. At this length, the S2 block co-locates with the S1 block so that the two blocks generate a bidisperse brush (insofar as the S1 and S2 lengths differ). This single-molecule analog to binary block copolymer blends affords unique opportunities for materials design at sub-microdomain length scales and provides insight into the transition from diblock to triblock copolymer (and thermoplastic elastomeric nature). In the second case, I explore the distribution of molecular and nanoscale additives in microphase-ordered block copolymers and demonstrate via SCFT that an interfacial excess, which depends strongly on additive concentration, selectivity and relative size, develops. These predictions are in agreement with experimental findings. Moreover, using a

  9. Blends of Thermoplastic Polyurethane and Polydimethylsiloxane Rubber: Assessment of Biocompatibility and Suture Holding Strength of Membranes

    PubMed Central

    Al-Ghamdi, Ahmed; Parameswar, Ramesh; Nando, G. B.

    2013-01-01

    In the present investigation, a compatibilized blend of thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS) is prepared by using copolymer of ethylene and methyl acrylate (EMA) as a reactive compatibilizer. Detailed in vitro biocompatibility studies were carried out for this compatibilized blend and the material was found noncytotoxic towards L929 mouse fibroblast subcutaneous connective tissue cell line. Microporosity was created on the surface of membranes prepared from the blend material by adopting the crazing mechanism. Cell proliferation and growth studies on the membranes surface showed that the microporous surface favoured ingrowth of the cells compared with a nonmicroporous surface. Suture holding strength studies indicate that the microporous membranes have enough strength to withstand the cutting and tearing forces through the suture hole. This blend material could be evaluated further to find its suitability in various implant applications. PMID:24454376

  10. Blends of thermoplastic polyurethane and polydimethylsiloxane rubber: assessment of biocompatibility and suture holding strength of membranes.

    PubMed

    Rajan, Krishna Prasad; Al-Ghamdi, Ahmed; Parameswar, Ramesh; Nando, G B

    2013-01-01

    In the present investigation, a compatibilized blend of thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS) is prepared by using copolymer of ethylene and methyl acrylate (EMA) as a reactive compatibilizer. Detailed in vitro biocompatibility studies were carried out for this compatibilized blend and the material was found noncytotoxic towards L929 mouse fibroblast subcutaneous connective tissue cell line. Microporosity was created on the surface of membranes prepared from the blend material by adopting the crazing mechanism. Cell proliferation and growth studies on the membranes surface showed that the microporous surface favoured ingrowth of the cells compared with a nonmicroporous surface. Suture holding strength studies indicate that the microporous membranes have enough strength to withstand the cutting and tearing forces through the suture hole. This blend material could be evaluated further to find its suitability in various implant applications.

  11. Effects of mechanical properties of thermoplastic materials on the initial force of thermoplastic appliances.

    PubMed

    Kohda, Naohisa; Iijima, Masahiro; Muguruma, Takeshi; Brantley, William A; Ahluwalia, Karamdeep S; Mizoguchi, Itaru

    2013-05-01

    To measure the forces delivered by thermoplastic appliances made from three materials and investigate effects of mechanical properties, material thickness, and amount of activation on orthodontic forces. Three thermoplastic materials, Duran (Scheu Dental), Erkodur (Erkodent Erich Kopp GmbH), and Hardcast (Scheu Dental), with two different thicknesses were selected. Values of elastic modulus and hardness were obtained from nanoindentation measurements at 28°C. A custom-fabricated system with a force sensor was employed to obtain measurements of in vitro force delivered by the thermoplastic appliances for 0.5-mm and 1.0-mm activation for bodily tooth movement. Experimental results were subjected to several statistical analyses. Hardcast had significantly lower elastic modulus and hardness than Duran and Erkodur, whose properties were not significantly different. Appliances fabricated from thicker material (0.75 mm or 0.8 mm) always produced significantly greater force than those fabricated from thinner material (0.4 mm or 0.5 mm). Appliances with 1.0-mm activation produced significantly lower force than those with 0.5-mm activation, except for 0.4-mm thick Hardcast appliances. A strong correlation was found between mechanical properties of the thermoplastic materials and force produced by the appliances. Orthodontic forces delivered by thermoplastic appliances depend on the material, thickness, and amount of activation. Mechanical properties of the polymers obtained by nanoindentation testing are predictive of force delivery by these appliances.

  12. Hierarchically UVO patterned elastomeric and thermoplastic structures

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Kulkarni, Manish; Marshall, Allan; Karim, Alamgir

    2014-03-01

    We demonstrate a simple yet versatile method to fabricate tunable hierarchical micro-nanostructures on flexible Poly(dimethylsiloxane) (PDMS) elastomer and thermoplastic polymer surface by a two-step process. Nanoscale patterned PDMS was obtained by imprinting compact disc (CD)/digital video disc (DVD) patterns. The second micro pattern was superposed by selective densification of PDMS by exposing to ultraviolet-ozone radiation (UVO) through micro-patterned TEM grid as a mask. The nanoscale patterns are preserved through UVO exposure step leading to formation of deep hierarchical patterns, so that for a 19 um square mesh, the micro pattern has a depth of 600nm with 6h PDMS UVO exposure time. This simple method can be promoted to fabricate hierarchical structures of thermoplastic materials (such as polystyrene), from which the mechanism of capillary imprinting and thermal stability of hierarchical patterns are investigated. This study is potentially important to various applications ranging from biomimetic scaffolds to solar cell.

  13. A dual plate thermoplastic recording device for holographic interferometry

    NASA Technical Reports Server (NTRS)

    Umstatter, Holly L.; Craig, James E.; Trolinger, James D.; Lee, George

    1986-01-01

    The development of a dual plate holographic interferometer using thermoplastic recording devices is described. The operational characteristics of the thermoplastic devices are investigated and optimized for fringe contrast and signal-to-noise ratio. The dual plate device was demonstrated in a transonic wind tunnel at NASA Ames Research Center. The interferograms derived from the thermoplastic device are compared with those derived from conventional photographic emulsions. The fringe contrast achieved with the optimized thermoplastic device is equivalent to the contrast achieved with conventional techniques.

  14. Patternable Solvent-Processed Thermoplastic Graphite Electrodes.

    PubMed

    Klunder, Kevin J; Nilsson, Zach; Sambur, Justin B; Henry, Charles S

    2017-09-13

    Since their invention in the 1950s, composite carbon electrodes have been employed in a wide variety of applications, ranging from batteries and fuel cells to chemical sensors, because they are easy to make and pattern at millimeter scales. Despite their widespread use, traditional carbon composite electrodes have substandard electrochemistry relative to metallic and glassy carbon electrodes. As a result, there is a critical need for new composite carbon electrodes that are highly electrochemically active, have universal and easy fabrication into complex geometries, are highly conductive, and are low cost. Herein, a new solvent-based method is presented for making low-cost composite graphite electrodes containing a thermoplastic binder. The electrodes, which are termed thermoplastic electrodes (TPEs), are easy to fabricate and pattern, give excellent electrochemical performance, and have high conductivity (700 S m(-1)). The thermoplastic binder enables the electrodes to be hot embossed, molded, templated, and/or cut with a CO2 laser into a variety of intricate patterns. Crucially, these electrodes show a marked improvement in peak current, peak separation, and resistance to charge transfer over traditional carbon electrodes. The impact of electrode composition, surface treatment (sanding, polishing, plasma treatment), and graphite source were found to significantly impact fabrication, patterning, conductivity, and electrochemical performance. Under optimized conditions, electrodes generated responses similar to more expensive and difficult to fabricate graphene and highly oriented pyrolytic graphite electrodes. The TPE electrode system reported here provides a new approach for fabricating high performance carbon electrodes with utility in applications ranging from sensing to batteries.

  15. Fiber reinforced thermoplastic resin matrix composites

    NASA Technical Reports Server (NTRS)

    Jones, Robert J. (Inventor); Chang, Glenn E. C. (Inventor)

    1989-01-01

    Polyimide polymer composites having a combination of enhanced thermal and mechanical properties even when subjected to service temperatures as high as 700.degree. F. are described. They comprise (a) from 10 to 50 parts by weight of a thermoplastic polyimide resin prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and (b) from 90 to 50 parts by weight of continuous reinforcing fibers, the total of (a) and (b) being 100 parts by weight. Composites based on polyimide resin formed from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and pyromellitic dianhydride and continuous carbon fibers retained at least about 50% of their room temperature shear strength after exposure to 700.degree. F. for a period of 16 hours in flowing air. Preferably, the thermoplastic polyimide resin is formed in situ in the composite material by thermal imidization of a corresponding amide-acid polymer prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. It is also preferred to initially size the continuous reinforcing fibers with up to about one percent by weight of an amide-acid polymer prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. In this way imidization at a suitable elevated temperature results in the in-situ formation of a substantially homogeneous thermoplastic matrix of the polyimide resin tightly and intimately bonded to the continuous fibers. The resultant composites tend to have optimum thermo-mechanical properties.

  16. Resilient bioresorbable copolymers based on trimethylene carbonate, L-lactide, and 1,5-dioxepan-2-one.

    PubMed

    Andronova, Natalia; Albertsson, Ann-Christine

    2006-05-01

    The new combinations of monomers presented in this work were evaluated in order to create an elastic material for potential application in soft tissue engineering. Thermoplastic elastomers (TPE) of trimethylene carbonate (TMC) with L-lactide (LLA) and 1,5-dioxepan-2-one (DXO) have been synthesized using a cyclic five-membered tin alkoxide initiator. The block copolymers were designed in such a way that poly(trimethylene carbonate-co-1,5-dioxepan-2-one) formed an amorphous middle block and the poly(L-lactide) (PLLA) formed semicrystalline terminal blocks. The amorphous middle block consisted of relatively randomly distributed TMC and DXO monomer units, and the defined block structure of the PLLA terminal segments was confirmed by 13C NMR. The properties of the TMC-DXO-LLA copolymers were compared with those of triblock copolymers based either on LLA-TMC or on LLA-DXO. Differential scanning calorimetry and dynamic mechanical analysis data confirmed the micro-phase separation in the copolymers. The mechanical properties of the copolymers were evaluated using tensile testing and cycling loading. All of the copolymers synthesized showed a highly elastic behavior. The properties of copolymers could be tailored by altering the proportions of the different monomers.

  17. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    McCool, Raurí; Murphy, Adrian; Wilson, Ryan; Jiang, Zhenyu; Price, Mark

    2011-05-01

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available

  18. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

    McCool, Rauri; Murphy, Adrian; Wilson, Ryan; Jiang Zhenyu; Price, Mark

    2011-05-04

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available

  19. Olefinic Thermoplastic Elastomer Gels: Combining Polymer Crystallization and Microphase Separation in a Selective Solvent

    SciTech Connect

    Armstrong, Daniel P.; Mineart, Kenneth P.; Lee, Byeongdu; Spontak, Richard J.

    2016-01-01

    Since selectively swollen thermoplastic elastomer gels (TPEGs) afford a wide range of beneficial properties that open new doors to developing elastomer-based technologies, we examine the unique structure−property behavior of TPEGs composed of olefinic block copolymers (OBCs) in this study. Unlike their styrenic counterparts typically possessing two chemically different blocks, this class of multiblock copolymers consists of linear polyethylene hard blocks and poly(ethylene-co-α-octene) soft blocks, in which case, microphase separation between the hard and the soft blocks is accompanied by crystallization of the hard blocks. Here, we prepare olefinic TPEGs (OTPEGs) through the incorporation of a primarily aliphatic oil that selectively swells the soft block and investigate the resultant morphological features through the use of polarized light microscopy and small-/wideangle X-ray scattering. These features are correlated with thermal and mechanical property measurements from calorimetry, rheology, and extensiometry to elucidate the roles of crystallization and self-assembly on gel characteristics and establish useful structure−property relationships.

  20. Olefinic Thermoplastic Elastomer Gels: Combining Polymer Crystallization and Microphase Separation in a Selective Solvent

    DOE PAGES

    Armstrong, Daniel P.; Mineart, Kenneth P.; Lee, Byeongdu; ...

    2016-11-01

    Since selectively swollen thermoplastic elastomer gels (TPEGs) afford a wide range of beneficial properties that open new doors to developing elastomer-based technologies, in this study we examine the unique structure-property behavior of TPEGs composed of olefinic block copolymers (OBCs). Unlike their styrenic counterparts typically possessing two chemically different blocks, this class of multiblock copolymers consists of linear polyethylene hard blocks and poly(ethylene-co-α-octene) soft blocks, in which case, microphase separation between the hard and the soft blocks is accompanied by crystallization of the hard blocks. We prepare olefinic TPEGs (OTPEGs) through the incorporation of a primarily aliphatic oil that selectively swellsmore » the soft block and investigate the resultant morphological features through the use of polarized light microscopy and small-/wideangle X-ray scattering. These features are correlated with thermal and mechanical property measurements from calorimetry, rheology, and extensiometry to elucidate the roles of crystallization and self-assembly on gel characteristics and establish useful structure-property relationships.« less

  1. Olefinic Thermoplastic Elastomer Gels: Combining Polymer Crystallization and Microphase Separation in a Selective Solvent

    SciTech Connect

    Armstrong, Daniel P.; Mineart, Kenneth P.; Lee, Byeongdu; Spontak, Richard J.

    2016-11-01

    Since selectively swollen thermoplastic elastomer gels (TPEGs) afford a wide range of beneficial properties that open new doors to developing elastomer-based technologies, in this study we examine the unique structure-property behavior of TPEGs composed of olefinic block copolymers (OBCs). Unlike their styrenic counterparts typically possessing two chemically different blocks, this class of multiblock copolymers consists of linear polyethylene hard blocks and poly(ethylene-co-α-octene) soft blocks, in which case, microphase separation between the hard and the soft blocks is accompanied by crystallization of the hard blocks. We prepare olefinic TPEGs (OTPEGs) through the incorporation of a primarily aliphatic oil that selectively swells the soft block and investigate the resultant morphological features through the use of polarized light microscopy and small-/wideangle X-ray scattering. These features are correlated with thermal and mechanical property measurements from calorimetry, rheology, and extensiometry to elucidate the roles of crystallization and self-assembly on gel characteristics and establish useful structure-property relationships.

  2. Imprinting of confining sites for cell cultures on thermoplastic substrates

    NASA Technical Reports Server (NTRS)

    Cone, C. D.; Fleenor, E. N.

    1969-01-01

    Prevention of test cell migration beyond the field of observation involves confining cells or cultures in microlagoons made in either a layer of grease or a thermoplastic substrate. Thermoplastic films or dishes are easily imprinted with specifically designed patterns of microlagoons.

  3. Synthesis and characterization of brush-like multigraft copolymers PnBA-g-PMMA by a combination of emulsion AGET ATRP and emulsion polymerization.

    PubMed

    Li, Hui; Wang, Wenwen; Li, Chunmei; Tan, Jiaojun; Yin, Dezhong; Zhang, Hepeng; Zhang, Baoliang; Yin, Changjie; Zhang, Qiuyu

    2015-09-01

    In this paper, poly(n-butyl acrylate)-g-poly(methyl methacrylate) multigraft copolymers were synthesized by macromonomer technique and miniemulsion copolymerization. The PMMA macromonomers were obtained by an activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) in emulsion system and subsequent allylation. Then the copolymerization of different macromonomers with nBA was carried out in miniemulsion system, obtaining multigraft copolymers with high molecular weight. The latex particles and distribution of emulsion AGET ATRP and miniemulsion copolymerization were characterized using laser light scattering. The molecular weight and polydispersity indices of macromonomers and multigraft copolymers were analyzed by gel permeation chromatography, and the number-average molecular weight range is 187,600-554,800 g/mol for PnBA-g-PMMA copolymers. In addition, the structural characteristics of macromonomer and brush-like copolymers were determined by infrared spectra and (1)H nuclear magnetic resonance spectroscopy. The thermal performance of brush-like copolymers were characterized by differential scanning calorimetry and thermogravimetric analysis. Atomic force microscopy results showed that the degree of microphase separation was varying with increasing PMMA content in PnBA-g-PMMA. The dynamic rheometer analysis revealed that multigraft copolymer with PMMA content of 31.4% exhibited good elastomeric properties to function as a TPE. These multigraft copolymers show a promising low cost and environmental friendly thermoplastic elastomer. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Structure-property relationships of polyisobutylene- block-polyamide thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Hooks, Edward T., Jr.

    Thermoplastic elastomers (TPEs) are a class of polymer fit for a wide variety of applications due to their customizability. In the synthesis of these types of materials, an elastically-performing polymer, deemed the "soft block," is combined with a stiffer "hard block" polymer, each of which can be selected based on their own specific properties in order to achieve desired material behavior in the final copolymer. Recently, the use of polyisobutylene as a soft block in combination with a polyamide hard block has been investigated for use in TPE synthesis. While the material showed some promising behavior, many properties were still below those of the commercially standard TPE material PebaxRTM. Polyisobutylene and polyamide samples of varying molecular weights and types were synthesized and combined in different ratios to form a variety of polyisobutylene-block-polyamide (PIB-PA) samples. Mechanical stirring as opposed to magnetic mixing and an increase in the soft block component of the copolymer were the most important adjustments made from previous PIB-PA syntheses. The effect of overall block length and the incorporation of a wider variety of polyamide (PA) types were also investigated. Mechanical stirring allowed for the achievement of higher molecular weights, and use of PA-6,6 as a hard block also produced a TPE with a markedly higher melting point than previously witnessed. Increasing the PIB content as well as using longer blocks of both precursors produced tougher copolymers, allowing them to undergo more mechanical deformation before failure as compared to previous PIB-PA formulations.

  5. Method of forming a foamed thermoplastic polymer

    DOEpatents

    Duchane, D.V.; Cash, D.L.

    1984-11-21

    A solid thermoplastic polymer is immersed in an immersant solution comprising a compatible carrier solvent and an infusant solution containing an incompatible liquid blowing agent for a time sufficient for the immersant solution to infuse into the polymer. The carrier solvent is then selectively extracted, preferably by a solvent exchange process in which the immersant solution is gradually diluted with and replaced by the infusant solution, so as to selectively leave behind the infustant solution permanently entrapped in the polymer. The polymer is then heated to volatilize the blowing agent and expand the polymer into a foamed state.

  6. Program For Two-Dimensional Thermoplastic Deformation

    NASA Technical Reports Server (NTRS)

    Orient, George E.

    1993-01-01

    SOLAS contains number of utility programs for use with finite-element simulations. Designed to handle two-dimensional problems of quasi-static thermoplastic deformation. Includes optional postprocessing software, independent of solution codes, generating unified element-by-element list of quantitative results of computation, plus file containing signed equivalent stresses, equivalent strains, and multiaxiality factor parameter. Signs of equivalent quantities expressed either with respect to maximum principal quantities or with respect to directions defined by user. Written in UNIX shell script and FORTRAN 77.

  7. Radiation effects on carbon fiber reinforced thermoplastics

    SciTech Connect

    Sasuga, Tsuneo; Udagawa, Akira; Seguchi, Tadao

    1993-12-31

    Polyether-ether-ketone (PEEK) and a newly developed thermoplastic polyimide ``new-TPI`` were applied to carbon fiber reinforced plastic (CFRP) as a matrix resin. PEEK and new-TPI showed excellent resistance over 50 MGy to electron irradiation and the crosslinking proceeded predominantly by irradiation. The changes in mechanical properties induced by electron irradiation of the CFRP with the two resins were examined at various temperatures. The flexural strength and modulus measured at {minus}196 and 25{degree}C were scarcely affected up to 120 MGy and both the values measured at high temperature were increased with dose.

  8. Thermoforming continuous fiber-reinforced thermoplastic composites

    SciTech Connect

    Wu, Xiang.

    1990-01-01

    In this research the forming process was first decomposed into basic deformation elements with simple geometries, and models were then developed for these elements. A series-parallel model was developed for predicting the upper and lower bounds of composite shear modulus at forming temperature based on the fiber content, fiber distribution, and matrix shear modulus. A shear-flexure model was proposed to describe the initial load-deflection behavior of thermoplastic composites in bending. A ply buckling model was developed which included the contributions from both a surface tension term and a ply buckling term.

  9. Model of holographic recording in thermoplastic materials.

    PubMed

    Bányász, I

    1998-04-10

    A method for the evaluation of images reconstructed from holograms recorded in thermoplastic materials is reported. The method is based on the use of the experimental modulation transfer function and nonlinear holographic characteristics of the recording material. Calculations have been carried out for high-numerical-aperture holograms of a five-element Ronchi ruling. The quality of the reconstructed image as a function of the recording parameters has been computed. The model predicts that it is possible to optimize holographic recording in these materials.

  10. Nanoembossing of thermoplastic polymers for microfluidic applications

    NASA Astrophysics Data System (ADS)

    Studer, V.; Pépin, A.; Chen, Y.

    2002-05-01

    We present a method for the fabrication of plastic microfluidic devices based on nanoembossing and thermal bonding. By nanoembossing of thermoplastic polymer pellets, both microfluidic deep channels and high resolution features can be formed using a silicon mold fabricated by electron beam lithography and reactive ion etching. By thermal bonding with another plastic sheet, the fabricated microfluidic devices can be sealed without clogging. Observation of pressure driven and electrokinetic flows through high density pillar arrays indicates the feasibility of nanofluidic analysis using plastic devices.

  11. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G.; Matzger, Adam J.; Benin, Annabelle I.; Willis, Richard R.

    2012-12-04

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  12. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2012-11-13

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  13. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2014-11-11

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  14. Ultraviolet absorbing copolymers

    DOEpatents

    Gupta, Amitava; Yavrouian, Andre H.

    1982-01-01

    Photostable and weather stable absorping copolymers have been prepared from acrylic esters such as methyl methacrylate containing 0.1 to 5% of an 2-hydroxy-allyl benzophenone, preferably the 4,4' dimethoxy derivative thereof. The pendant benzophenone chromophores protect the acrylic backbone and when photoexcited do not degrade the ester side chain, nor abstract hydrogen from the backbone.

  15. Multiblock thermoplastic polyurethanes for biomedical and shape memory applications

    NASA Astrophysics Data System (ADS)

    Gu, Xinzhu

    Polyurethanes are a class of polymers that are capable of tailoring the overall polymer structure and thus final properties by many factors. The great potential in tailoring polymer structures imparts PUs unique mechanical properties and good cytocompatibility, which make them good candidates for many biomedical devices. In this dissertation, three families of multiblock thermoplastic polyurethanes are synthesized and characterized for biomedical and shape memory applications. In the first case described in Chapters 2, 3 and 4, a novel family of multiblock thermoplastic polyurethanes consisting of poly(ɛ-caprolactone) (PCL) and poly(ethylene glycol) (PEG) are presented. These materials were discovered to be very durable, with strain-to-break higher than 1200%. Heat-triggered reversible plasticity shape memory (RPSM) was observed, where the highly deformed samples completely recovered their as-cast shape within one minute when heating above the transition temperature. Instead of conventional "hard" blocks, entanglements, which result from high molecular weight, served as the physical crosslinks in this system, engendering shape recovery and preventing flow. Moreover, water-triggered shape memory effect of PCL-PEG TPUs is explored, wherein water permeated into the initially oriented PEG domains, causing rapid shape recovery toward the equilibrium shape upon contact with liquid water. The recovery behavior is found to be dependent on PEG weight percentage in the copolymers. By changing the material from bulk film to electrospun fibrous mat, recovery speed was greatly accelerated. The rate of water recovery was manipulated through structural variables, including thickness of bulk film and diameter of e-spun webs. A new, yet simple shape memory cycle, "wet-fixing" is also reported, where both the fixing and recovery ratios can be greatly improved. A detailed microstructural study on one particular composition is presented, revealing the evolution of microphase

  16. Properties of radiation cured vinyl-divinyl copolymers. Part I. Thermomechanical properties of crosslinked methyl methacrylate polymers

    SciTech Connect

    Micko, M.M.; Paszner, L.

    1980-01-01

    Radiation copolymerization (crosslinking) of methyl methacrylate (MMA) with a series of divinyl monomers containing 1 to 4 ethyleneglycol connecting units between the terminal reactive divinyl units was found to provide numerous improvements in the thermomechanical properties of the copolymers. Thermoplastic poly-MMA was converted to a thermoset copolymer with only small additions (2 to 5%) of the divinyl crosslinking agent. When the measured thermomechanical properties (glass transition temperature, Tg, thermal distortion temperature, TDT; and thermomechanical deformation degree, TDD) of the above crosslinked copolymers were related to the respective crosslink densities (expressed by the copolymer connection number, CN/sub co/) the crosslink efficiency increased in terms of the above parameters in a reverse order as observed for acceleration, i.e., TEGDMA < TrEGDMA < DEGDMA < EGDMA. This observation is readily explained by the relation between segmental mobility of the respective macromolecules of the copolymers formed and the critical thermomechanical parameters which can be determined for such solid copolymers. Segmental mobility of the crosslinking agent increases with increasing molecular bridge length and hence the increased temperature sensitivity of the copolymers to thermal softening and distortion as the bridge length increases from a single ethyleneglycol (EGDMA) to four ethyleneglycol (TEGDMA) units in the bridge connecting the vinyl functions of the divinyl monomers. For all copolymers of this study, the linear thermomechanical deformation coefficient, representing thermal deformation between the plastic and rubbery states, remained relatively constant across a broad temperature interval until the respective TDT temperatures are reached, and decreased exponentially with the divinyl monomer concentration in the copolymer regardless of the connecting bridge length.

  17. An Innovative Approach to Retention: Thermoplastic Retainer.

    PubMed

    Ozeer, K A Adam; David, Sumitha A; Mohamed, Umar; Sunil, P C; Paul, Sam; Paul, Parson

    2017-07-01

    The aim of this study was to design and introduce a retainer that overcomes the common shortcomings seen in other retainers. Hard thermoplastic sheet of 0.5 mm thickness is vacuum or pressure-molded onto the patient cast. Lingual portion of the retainer is trimmed according to the contours of the anterior teeth. Contact points between the maxillary and mandibular anterior teeth are marked on the retainer and reduced. Punch cut holes are placed on the retainer for the exit of flash and air bubbles while fixation. The retainer is bonded onto the lingual surface of the anterior teeth using composite. A 1-month review of the retainer showed no patient discomfort, occlusal interference, or bond failure. The aim of the article was found to have been achieved. Initial evaluation has shown positive findings. Long-term clinical findings will determine the overall success of this new retainer. As compared with other retainers, thermoplastic retainer has shown reduced tendency to debond from occlusal forces, decreased patient discomfort, and occlusal interference.

  18. Supportability evaluation of thermoplastic and thermoset composites

    NASA Technical Reports Server (NTRS)

    Chanani, G. R.; Boldi, D.; Cramer, S. G.; Heimerdinger, M. W.

    1990-01-01

    Nearly 300 advanced composite components manufactured by Northrop Corporation are flying on U.S. Air Force and U.S. Navy supersonic aircraft as part of a three-year Air Force/Navy/Northrop supportability evaluation. Both thermoplastic and high-temperature thermoset composites were evaluated for their in-service performance on 48 USAF and Navy F-5E fighter and USAFT-38 trainer aircraft in the first large-scale, long-term maintenance evaluation of these advanced materials. Northrop manufactured four types of doors for the project-avionics bay access, oil fill, inlet duct inspection, and a main landing gear door. The doors are made of PEEK (polyetheretherketone) thermoplastic, which is tougher and potentially less expensive to manufacture than conventional composites; and 5250-3 BMI (bismaleimide) thermoset, which is manufactured like a conventional epoxy composite but can withstand higher service temperatures. Results obtained so far indicate that both the BMI and PEEK are durable with PEEK being somewhat better than BMI.

  19. Acetylation of rice straw for thermoplastic applications.

    PubMed

    Zhang, Guangzhi; Huang, Kai; Jiang, Xue; Huang, Dan; Yang, Yiqi

    2013-07-01

    An inexpensive and biodegradable thermoplastic was developed through acetylation of rice straw (RS) with acetic anhydride. Acetylation conditions were optimized. The structure and properties of acetylated RS were characterized by fourier transform infrared (FTIR), solid-state (13)C NMR spectroscopy, X-ray diffractometer (XRD), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results showed that acetylation of RS has successfully taken place, and comparing with raw RS, the degree of crystallinity decreased and the decomposition rate was slow. The acetylated RS has got thermoplasticity when weight ratio of RS and acetic anhydride was 1:3, using sulphuric acid (9% to RS) as catalyst in glacial acetic acid 35°C for 12h, and the dosage of solvent was 9 times RS, in which weight percent gain (WPG) of the modified RS powder was 35.5% and its percent acetyl content was 36.1%. The acetylated RS could be formed into transparent thin films with different amount of plasticizer diethyl phthalate (DEP) using tape casting technology.

  20. A 69 cent look at thermoplastic softening

    NASA Technical Reports Server (NTRS)

    Vanasupa, Linda S.

    1993-01-01

    The objectives are to demonstrate the change in mechanical properties of a thermoplastic polymer when the polymer is heated above the glass transition temperature. The instructor or student can perform this demonstration. In preparation for the demonstration, fill the flask or beaker 3/4 full with water and bring the water to a boil. First observe the initial stiffness of the toothbrush by slightly flexing it. Note that it is fairly stiff and retains its initial shape when the forces are removed. If you were to apply enough force, the toothbrush would break in a somewhat brittle fashion. Now place the toothbrush in the boiling water for 2 minutes. After the 2 minutes are up, remove the toothbrush from the boiling water with the washcloth. At this time, you will be able to bend the toothbrush easily. When it cools it will retain this bent shape. You've just demonstrated heating the polymer above the glass transition temperature, demonstrating thermoplastic softening. Instructor notes are provided.

  1. Method and apparatus for extruding thermoplastic material

    SciTech Connect

    McKelvey, J.M.

    1985-02-26

    A gear pump assisted screw conveyor extrusion system utilizing a cartridge heating device disposed axially within the screw and having the drives for the gear pump and the screw correlated in speed to create relatively little pressure in the thermoplastic material being extruded such that relatively little mechanical working thereof occurs. The thermoplastic material is melted in the screw conveyor primarily by heat transfer from the cartridge heater and the gear pump is utilized for conveying the melted material under pressure to a subsequent work station. A relatively deep material-conveying spiral channel is provided in the screw for maximized extrusion output per revolution of the screw and minimized mechanical energy generation by the screw. A motionless mixer may be employed intermediate the screw and the work station to homogenize the melted material for reducing temperature gradients therein. The system advantageously is capable of extruding material at a substantially greater rate and a lower material temperature and with substantially increased power economy than conventional systems utilizing a high pressure, externally heated screw conveyor portion.

  2. Processing parameters for thermoplastic filament winding

    NASA Astrophysics Data System (ADS)

    Colton, J.; Leach, D.

    The consolidation pressure and winding speed for thermoplastic filament winding were studied. Thermoplastic composite parts were manufactured from tape prepreg (APC-2); powder-coated, semiconsolidated towpreg; and commingled fiber towpeg. The material used was carbon fiber (AS-4) (60 vol pct) in a PEEK matrix. The parts made were open-ended cylinders of the three materials, 177.8 mmID, 228.6 mm long, 17 plies thick with a 0 deg lay-up angle; and rings, 50 plies of APC-2 thick, 6.35 mm wide (one strip wide), 177.8 mm ID, and a lay-up of 0 deg. Their quality was determined by surface finish and void percentage. The tubes made from APC-2 appeared to have the best quality of the three prepregs. For the rings, the speed of lay down had a significant effect on both the final width of the parts and on the percentage of voids. The pressure of the roller had a significant effect on the final widths at a 99 percent confidence level, but only a significant effect on the percentage of voids at a 95 percent confidence level.

  3. Acoustic and ultrasonic characterization constraints of self-healing (ethylene-co-methacrylic acid) copolymers

    NASA Astrophysics Data System (ADS)

    Pestka, Kenneth, II; Buckley, Jonathan; Kalista, Stephen; Bowers, Nicholas

    Recent experiments indicate that small sample poly (ethylene-co-methacrylic acid) copolymers (EMAA copolymers) exhibit time dependent variation in their acoustic and ultrasonic resonant spectra after exposure to a damage event. However, due to the relatively soft nature of these thermoplastic materials, several experimental constraints affect efficacy of resonant spectral analysis. In this work we will the address the effect of several characterization constraints on a self-healing EMAA ionomer (commercially known as Dupont Surlyn 8920) including the effects of transducer loading, continuous rapid resonant excitation and temporally separated long-term resonant excitation. In some circumstances, these experimental constraints can influence the time dependence of sample resonant frequency evolution, quality factor, and variation in spectral waveform. By quantifying these effects, robust characterization of post-damage self-healing EMAA samples is possible and will be presented.

  4. Thermal monitoring of the thermoplastic injection molding process with FBGs

    NASA Astrophysics Data System (ADS)

    Alberto, Nélia J.; Nogueira, Rogério N.; Neto, Victor F.

    2014-08-01

    Injection molding is an important polymer processing method for manufacturing plastic components. In this work, the thermal monitoring of the thermoplastic injection molding is presented, since temperature is a critical parameter that influences the process features. A set of fiber Bragg gratings were multiplexed, aiming a two dimensional monitoring of the mold. The results allowed to identify the different stages of the thermoplastic molding cycle. Additionally, the data provide information about the heat transfer phenomena, an important issue for the thermoplastic injection sector, and thus for an endless number of applications that employ this type of materials.

  5. Processing carbon nanotube/thermoplastic composites for enhanced mechanical strength

    NASA Astrophysics Data System (ADS)

    Peng, Kern

    Carbon nanotube (CNT)/thermoplastic composites have many potential applications. However, processing CNT/thermoplastic composites has been extremely challenging due to the inherently strong affinity of CNT to themselves. Two major issues in processing CNT/thermoplastic composites for enhanced mechanical properties are achieving uniform dispersion and producing alignment of the nanotubes in the polymer matrix. This study used a combination of surfactant-aided mixing, extrusion, and various drawing processing techniques to successfully obtain significant improvement of nanotube dispersion and alignment in a semi-crystalline polymer matrix.

  6. Imide/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor); Bass, Robert G. (Inventor)

    1992-01-01

    Imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly(arylene ethers) in polar aprotic solvents and by chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The resulting block copolymers have one glass transition temperature or two, depending upon the particular structure and/or the compatibility of the block units. Most of these block copolymers form tough, solvent resistant films with high tensile properties.

  7. Block copolymer battery separator

    DOEpatents

    Wong, David; Balsara, Nitash Pervez

    2016-04-26

    The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

  8. Clickable Amphiphilic Triblock Copolymers.

    PubMed

    Isaacman, Michael J; Barron, Kathryn A; Theogarajan, Luke S

    2012-06-15

    Amphiphilic polymers have recently garnered much attention due to their potential use in drug-delivery and other biomedical applications. A modular synthesis of these polymers is extremely desirable since it offers precise individual block characterization and increased yields. We present here for the first time a modular synthesis of poly(oxazoline)-poly(siloxane)-poly(oxazoline) block copolymers that have been clicked together using the copper-catalyzed azide-alkyne cycloaddition reaction. Various click methodologies for the synthesis of these polymers have been carefully evaluated and optimized. The approach using copper nanoparticles was found to be the most optimal among the methods evaluated. Furthermore, these results were extended to allow for a reactive Si-H group-based siloxane middle block to be successfully clicked. This enables the design of more complex amphiphilic block copolymers that have additional functionality, such as stimuli responsiveness, to be synthesized via a simple hydrosilylation reaction.

  9. Lactic acid polymers: strong, degradable thermoplastics

    SciTech Connect

    Wehrenberg, R.H.

    1981-01-01

    Copolymers of lactic and glycolic acids are being developed by researchers at Battelle and elsewhere as renewable-resource plastics. Other uses include matrices for controlled release of drugs and pesticides as well as in prosthetic devices. In contrast to conventional plastics, lactic acid polymers are biodegradable, and after several months exposure to moisture, these materials convert back to natural harmless products. The properties of lactic acid polymers are examined.

  10. Imide/Arylene Ether Copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Hergenrother, Paul M.; Bass, Robert G.

    1991-01-01

    New imide/arylene ether copolymers prepared by reacting anhydride-terminated poly(amic acids) with amine-terminated poly(arylene ethers) in polar aprotic solvents. Each resulting copolymer may have one glass-transition temperature or two, depending on chemical structure and/or compatibility of block units. Most of copolymers form tough, solvent-resistant films with high tensile properties. Films cast from solution tough and flexible, and exhibit useful thermal and mechanical properties. Potentially useful as moldings, adhesives, or composite matrices. Because of flexible arylene ether blocks, these copolymers easier to process than polyimides.

  11. Analysis of melt copolymers.

    PubMed

    Montaudo, Maurizio S

    2007-01-01

    Melt copolymer chains are the main (most abundant) reaction product obtained when heating a blend of two (or more) condensation polymers (such as polyester + polycarbonate or polyester + polyamide or polyester + polyester) in which exchange reactions occur. In fact, during the melt-mixing reaction, an AB copolymer is formed and, as a consequence, the sample is a complex mixture made of three components or simply "parts", referred to as Z1, Z2 and Z3, where Z1 and Z2 are the parts for unreacted homopolymers (A and B), whereas Z3 is the part for the copolymer. In this paper, it is shown that matrix-assisted laser desorption/ionization mass spectrometry (and mass spectrometry in general) can be used to monitor the yield of the reactive blending reaction, YR, by measuring the amount of unreacted homopolymer (Z1 and Z2). In order to allow for comparisons, the paper also discusses conventional methods for measuring Z1 and Z2, such as liquid chromatography and nuclear magnetic resonance.

  12. Thermoplastic Single-Ply Roof Relieves Water Damage and Inconvenience.

    ERIC Educational Resources Information Center

    Williams, Jennifer Lynn

    2002-01-01

    Assesses use of thermoplastic single-ply roofs by North Carolina's Mars Hill College to prevent leaks, reduce maintenance costs, and enhance the value of their older historic buildings. Administrators comment on the roof's installation efficiency and cleanliness. (GR)

  13. Influence of oxidized starch on the properties of thermoplastic starch.

    PubMed

    Zhang, Yu-Rong; Wang, Xiu-Li; Zhao, Guo-Ming; Wang, Yu-Zhong

    2013-07-01

    Thermoplastic starch was prepared by adding oxidized starches and glycerol together into starch. The addition of oxidized starch improved the rheological properties and also increased the toughness of thermoplastic starch. Compared with TPS30, the elongation at break increased from 126.8% to 152.5% when 5wt% OS 117% was added. Good compatibility of thermoplastic starch between the matrix and oxidized starch was confirmed by SEM. The addition of oxidized starch lowered the storage modulus and glass transition temperature (Tg) of thermoplastic starch, decreasing Tg from 34.1 to 30°C when 10 wt% OS117% was added. The thermal stability of blending was improved by adding oxidized starches, i.e. when 5 wt% OS70% was added, T5% increased from 134 to 156°C. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Heating of thermoplastic-based unidirectional composite prepregs

    SciTech Connect

    Wang, X.; Weber, M.E.; Charrier, J.M. )

    1989-04-01

    Thermoplastic-based prepregs offer a potential for faster manufacture of composite products than with thermoset-based prepregs. The winding or controlled placement of thermoplastic-based prepreg tapes requires the rapid heating of the moving tape, just prior to its contact with the substrate on the mandrel. In the case of complex shapes, geometrical constraints and significant variations in tape speeds in the course of manufacture, make it particularly desirable to be able to model the heating process. A mathematical model and its experimental verification for convection/conduction heat transfer to and through either a homogeneous thermoplastic material, or thermoplastic-based unidirectional composites featuring glass, aramid and carbon fibers, is discussed. 12 refs.

  15. Induction Consolidation/Molding of Thermoplastic Composites Using Smart Susceptors

    SciTech Connect

    2009-02-01

    This factsheet describes a research project whose objective is to explore and define the technical and economic viability of induction consolidation for thermoplastic composites and to fabricate a wide spectrum of components in an energy-efficient manner.

  16. Manufacturing developments of filament winding for thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Kimura, Minoru; Saigoku, Haruyoshi; Tsuchiya, Kiyoshi; Ishikawa, Takashi

    Thermoplastic composite materials for aerospace structures are examined. A forming method for filament windings is described, and the hot pressing technology is discussed. The test results are given, and the nondestructive inspection of fracture surfaces is considered.

  17. Thermoplastic Single-Ply Roof Relieves Water Damage and Inconvenience.

    ERIC Educational Resources Information Center

    Williams, Jennifer Lynn

    2002-01-01

    Assesses use of thermoplastic single-ply roofs by North Carolina's Mars Hill College to prevent leaks, reduce maintenance costs, and enhance the value of their older historic buildings. Administrators comment on the roof's installation efficiency and cleanliness. (GR)

  18. Long-short fiber reinforced thermoplastics

    SciTech Connect

    Gore, C.R.; Cuff, G.; Cianelli, D.A.; Travis, J.E.

    1986-01-01

    This paper presents information on a new family of fiber-reinforced thermoplastic compounds developed by ICI PLC and now produced by LNP under the trade mark ''Verton.'' Production is by a pultrusion process, rather than by the usual compounding extruder, which enables a high level of impregnation to be achieved without damaging the fibers. The result in molded parts is a 0.24-0.40 inch (6-10 mm) typical fiber length versus 0.008-0.016 inches (0.2-0.4 mm) for conventional short fiber products. Consequently, this enables fabricators to achieve typically a 10 to 20-fold increase in average fiber length in the finished component. These long-short fiber reinforced compounds exhibit substantial property improvements over short fiber system. Processing conditions are similar to corresponding short fiber compounds.

  19. Thermoplastic starch films reinforced with talc nanoparticles.

    PubMed

    Castillo, Luciana; López, Olivia; López, Cintia; Zaritzky, Noemí; García, M Alejandra; Barbosa, Silvia; Villar, Marcelo

    2013-06-20

    Nanocomposite films of thermoplastic corn starch (TPS) with talc particles were obtained by thermo-compression in order to study the effect of filler on structure, optical, and thermal properties. Talc increased the films rigid phase, thus their cross-sections resulted more irregular. Talc preferential orientation within matrix and good compatibility between particles and TPS was observed by SEM. Slight crystalline structure changes in TPS matrix were measured by XRD and DSC, due to talc nucleating effect. Randomly dispersed talc nanoagglomerates and individual platelets were assessed by TEM. Laminar morphology and nano-sized particles allowed that nanocomposite films were optically transparent. TPS-talc films resulted heterogeneous materials, presenting domains rich in glycerol and others rich in starch. Talc incorporation higher than 3%, w/w increased softening resistance of the nanocomposites as stated by DMA. Relaxation temperatures of glycerol-rich phase shifted to higher values since talc reduces the mobility of starch chains.

  20. Thermoplastic Elastomers: Materials for Heart Assist Devices.

    PubMed

    Piegat, Agnieszka; Fray, Mirosława El

    2016-01-01

    Heart assisting devices have become a standard element in clinical practice and provide support for the traditional methods of treating heart disease. Regardless of the construction of VAD (ventricular assist devices), there are crucial requirements that have to be met by the construction materials: high purity, desired physical, chemical and mechanical properties, easy fabrication and high stability and susceptibility to sterilization. They must not cause thrombosis, destroy cellular elements, alter plasma protein, destroy enzymes, deplete electrolytes, cause immune response and cancer, and must not produce toxic and allergic reactions, when they are applied in direct contact with biological tissues and fluids. This paper provides an overview of the polymeric materials as construction materials for cardiovascular support systems, focusing on the group of thermoplastic elastomers, mainly polyurethane and polyester based ones. It also highlights the advantages and disadvantages of currently used materials and the progress in the design of new materials with potential application in the biomedical field.

  1. Thermoplastic polyimide NEW-TPI (trademark)

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Reddy, Rakasi M.

    1990-01-01

    Thermal and rheological properties of a commercial thermoplastic polyimide, NEW-TPI (trademark), were characterized. The as-received material possesses initially a transient crystallite form with a bimodal distribution in peak melting temperatures. After the melting of the initial crystallite structure, the sample can be recrystallized by various thermal treatments. A bimodal or single modal melting peak distribution is formed for annealing temperatures below or above 360 C, respectively. The recrystallized crystallinities are all transient in nature. The polymers are unable to be recrystallized after being subjected to elevated temperature annealing above 450 C. The recrystallization mechanism was postulated, and a simple kinetics model was found to describe the behavior rather satisfactory under the conditions of prolonged thermal annealing. Rheological measurements made in the linear viscoelastic range support the evidence observed in the thermal analysis. Furthermore, the measurements sustain the manufacturer's recommended processing window of 400 to 420 C for this material.

  2. Thermoplastic polymers for improved fire safety

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Parker, J. A.; Hilado, C. J.

    1976-01-01

    The thermochemical and flammability characteristics of some typical thermoplastic materials currently in use and others being considered for use in aircraft interiors are described. The properties studied included (1) thermomechanical properties such as glass transition and melt temperature, (2) changes in polymer enthalpy by differential scanning calorimetry, (3) thermogravimetric analysis in anaerobic and oxidative environments, (4) oxygen index, (5) smoke evolution, (6) relative toxicity of the volatile products of pyrolysis, and (7) selected physical properties. The generic polymers that were evaluated included: acrylonitrile butadiene styrene, bisphenol A polycarbonate, 9,9 bis (4-hydroxyphenyl) fluorene polycarbonatepoly (dimethyl siloxane) block polymer, phenolphthalein bisphenol A polycarbonate, phenolphthalein polycarbonate, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyaryl sulfone, chlorinated polyvinyl chloride homopolymer, polyvinyl fluoride, and polyvinylidene fluoride. Processing parameters, including molding characteristics of some of the advanced polymers, are described. Test results and relative ranking of some of the flammability, smoke, and toxicity properties are presented.

  3. Thermoplastic composite matrices with improved solvent resistance

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.; Jensen, B. J.; Havens, S. J.

    1984-01-01

    In order to improve solvent resistance of aromatic thermoplastic polymers, ethynyl-terminated aromatic sulfone polymers (ETS), sulfone/ester polymers (SEPE) containing pendent ethynyl groups, and phenoxy resin containing pendent ethynyl groups are synthesized. Cured polysulfones and phenoxy resins containing ethynyl groups on the ends or pendent on the molecules exhibited systematic behavior in solvent resistance, film flexibility, and toughness as a function of crosslink density. The film and composite properties of a cured solvent-resistant ETS were better than those of a commercially available solvent sensitive polysulfone. The study was part of a NASA program to better understand the trade-offs between solvent resistance, processability and mechanical properties which may be useful in designing composite structures for aerospace vehicles.

  4. ACT/ICAPS: Thermoplastic composite activities

    NASA Technical Reports Server (NTRS)

    Renieri, M. P.; Burpo, S. J.; Roundy, L. M.; Todd, S. M.

    1992-01-01

    McDonnell Aircraft Company (MCAIR) is teamed with Douglas Aircraft Company (DAC) under NASA's Advanced Composite Technology (ACT) initiative in a program entitled Innovative Composite Aircraft Primary Structures (ICAPS). Efforts at MCAIR have focused on the use of thermoplastic composite materials in the development of structural details associated with an advanced fighter fuselage section with applicability to transport design. Based on innovative design/manufacturing concepts for the fuselage section primary structure, elements were designed, fabricated, and structurally tested. These elements focused on key issues such as thick composite lugs and low cost forming of fastenerless, stiffener/moldline concepts. Manufacturing techniques included autoclave consideration, single diaphragm co-consolidation (SDCC), and roll-forming.

  5. Thermoplastic Ribbon-Ply Bonding Model

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.; Marchello, Joseph M.; Messier, Bernadette C.

    1996-01-01

    The aim of the present work was to identify key variables in rapid weldbonding of thermoplastic tow (ribbon) and their relationship to matrix polymer properties and to ribbon microstructure. Theoretical models for viscosity, establishment of ply-ply contact, instantaneous (Velcro) bonding, molecular interdiffusion (healing), void growth suppression, and gap filling were reviewed and synthesized. Consideration of the theoretical bonding mechanisms and length scales and of the experimental weld/peel data allow the prediction of such quantities as the time and pressure required to achieve good contact between a ribbon and a flat substrate, the time dependence of bond strength, pressures needed to prevent void growth from dissolved moisture and conditions for filling gaps and smoothing overlaps.

  6. Thermoplastic composite matrices with improved solvent resistance

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.; Jensen, B. J.; Havens, S. J.

    1984-01-01

    In order to improve solvent resistance of aromatic thermoplastic polymers, ethynyl-terminated aromatic sulfone polymers (ETS), sulfone/ester polymers (SEPE) containing pendent ethynyl groups, and phenoxy resin containing pendent ethynyl groups are synthesized. Cured polysulfones and phenoxy resins containing ethynyl groups on the ends or pendent on the molecules exhibited systematic behavior in solvent resistance, film flexibility, and toughness as a function of crosslink density. The film and composite properties of a cured solvent-resistant ETS were better than those of a commercially available solvent sensitive polysulfone. The study was part of a NASA program to better understand the trade-offs between solvent resistance, processability and mechanical properties which may be useful in designing composite structures for aerospace vehicles.

  7. Metallic glass-strengthened thermoplastic elastomer composites

    NASA Astrophysics Data System (ADS)

    Liu, Xue; Liu, Hao; Wang, Dong; Wang, Enpeng; Liu, Wenjian; Yao, Kefu; Chen, Na

    2017-06-01

    Thermoplastic elastomers (TPEs) and metallic glasses (MGs), both lack of long-range ordering structure, have different physical and mechanical properties. To combine unique viscoelasticity of elastomers and excellent wear resistance of MGs, we propose to introduce a Pd40Ni40Si4P16 MG into a commercial styrene-butadiene-styrene (SBS) TPE to form MG/TPE composites. Serving as a hard and strong second phase dispersed in the SBS matrix, the micrometer-sized MG particles can effectively improve the wear resistance of the matrix due to a strengthening effect. In particular, the MG/TPE composite with an addition of 60 wt% MG shows significantly enhanced wear resistance up to about three times that of the SBS matrix. The present results provide a new way to enhance the wear resistance of the widely used TPEs, which may generate immense economic value by extending their service life.

  8. Monitoring impact damaging of thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Boccardi, S.; Carlomagno, G. M.; Meola, C.; Russo, P.; Simeoli, G.

    2015-11-01

    Thermoplastic composites are becoming ever more attractive also to the aeronautical sector. The main advantage lies in the possibility to modify the interface strength of polypropylene based laminates by adjusting the composition of the matrix. Understanding these aspects is of great importance to establish a possible link between the material toughness and the matrix ingredients. The aim of the present work is to ascertain the ability of an infrared imaging device to visualize any change, in the material behaviour to low energy impact, induced by changes in the matrix composition. Attention is given to image processing algorithms; in particular, an original procedure to measure the extension of the impact-affected area is proposed.

  9. Large area in situ fabrication of poly(pyrrole)-nanowires on flexible thermoplastic films using nanocontact printing

    NASA Astrophysics Data System (ADS)

    Garcia-Cruz, Alvaro; Lee, Michael; Marote, Pedro; Zine, Nadia; Sigaud, Monique; Bonhomme, Anne; Pruna, Raquel; Lopez, Manuel; Bausells, Joan; Jaffrezic, Nicole; Errachid, Abdelhamid

    2016-08-01

    Highly efficient nano-engineering tools will certainly revolutionize the biomedical and sensing devices research and development in the years to come. Here, we present a novel high performance conducting poly(pyrrole) nanowires (PPy-NW) patterning technology on thermoplastic surfaces (poly(ethylene terephthalate (PETE), poly(ethylene 2,6-naphthalate (PEN), polyimide (PI), and cyclic olefin copolymer) using nanocontact printing and controlled chemical polymerization (nCP-CCP) technique. The technique uses a commercial compact disk as a template to produce nanopatterned polydimethylsiloxane (PDMS) stamps. The PDMS nanopatterned stamp was applied to print the PPy-NWs and the developed technology of nCP-CCP produced 3D conducting nanostructures. This new and very promising nanopatterning technology was achieved in a single step and with a low cost of fabrication over large areas.

  10. Forming of fiber reinforced thermoplastic sheets

    SciTech Connect

    Bhattacharyya, D.; Burt, C.R.; Martin, T.A.

    1993-12-31

    The development of fiber reinforced thermoplastic (FRTP) sheets has added a new dimension to the manufacturing industry. The ability of the thermoplastic matrix to soften and melt with the application of heat allows secondary processing of these composites. The material can be formed into components using conventional sheet metal forming processes with necessary modification. Ideally this opens the way for low cycle-time, non-labor intensive manufacturing processes. However, before there can be any wide scale application of the fiber reinforced sheet material, a better understanding is required regarding the formability of these reinforced sheets and the parameters influencing their forming characteristics. In sheet metal industry the term formability is described as the ease of forming and can be judged by various factors which may vary with the needs of a particular manufacturer. It is not always easy to prejudge formability as in many instances the actual sheet forming mechanism is quite complex. However, often a reasonable understanding of the process characteristics can be obtained through some relatively simple laboratory experiments. The present paper describes the results of a series of such tests namely hemispherical dome forming, cup drawing and vee bending using mainly polypropylene/glass fiber composite sheets with various fiber architecture, forming temperature and speed. Grid strain analysis has been applied to measure the magnitudes and directions of the principal strains and how they are influenced by fiber orientation. A kinematic approach has been shown to theoretically predict the deformation pattern with reasonable accuracy. Some salient features such as fiber buckling, sheet wrinkling, springback have been discussed in the context of forming process variables.

  11. Effect of annealing history on free volume in thermoplastics

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; St.clair, T. L.

    1986-01-01

    Two different types of thermoplastic glassy polymers have been investigated for the effects of thermal annealing on their free volumes. It has been observed that free volumes in glassy polymers decrease asymptotically to a steady level after about four thermal anneals lasting for 24 hours at a temperature about 50 C below their glass transition temperatures. These results indicate that composites incorporating properly annealed thermoplastic matrices may not experience any additional internal stresses due to subsequent thermal excursions experienced while in service.

  12. Methods for Preparing Nanoparticle-Containing Thermoplastic Composite Laminates

    NASA Technical Reports Server (NTRS)

    Gruber, Mark B. (Inventor); Jensen, Brian J. (Inventor); Cano, Roberto J. (Inventor)

    2016-01-01

    High quality thermoplastic composites and composite laminates containing nanoparticles and/or nanofibers, and methods of producing such composites and laminates are disclosed. The composites comprise a thermoplastic polymer and a plurality of nanoparticles, and may include a fibrous structural reinforcement. The composite laminates are formed from a plurality of nanoparticle-containing composite layers and may be fused to one another via an automated process.

  13. Some properties of thermoplastic mixtures for forming ceramics by extrusion

    SciTech Connect

    Mosin, Yu.M.; Leonov, V.G.

    1995-11-01

    The change in the rheological properties of mixtures for plastic forming based on cordierite and aluminum nitride as a function of the composition of the thermoplastic binder and the temperature is considered. A supposition on the influence of the ratio between the crystalline and the amorphous components of the thermoplastic dispersion medium on the properties of the mixture is made. Some recommendations on forming of ceramic pieces are given.

  14. Spontaneously Healable Thermoplastic Elastomers Achieved through One-Pot Living Ring-Opening Metathesis Copolymerization of Well-Designed Bulky Monomers.

    PubMed

    Yang, Ji-Xing; Long, Ying-Yun; Pan, Li; Men, Yong-Feng; Li, Yue-Sheng

    2016-05-18

    We report here a series of novel spontaneously healable thermoplastic elastomers (TPEs) with a combination of improved mechanical and good autonomic self-healing performances. Hard-soft diblock and hard-soft-hard triblock copolymers with poly[exo-1,4,4a,9,9a,10-hexahydro-9,10(1',2')-benzeno-l,4-methanoanthracene] (PHBM) as the hard block and secondary amide group containing norbornene derivative polymer as the soft block were synthesized via living ring-opening metathesis copolymerization by use of Grubbs third-generation catalyst through sequential monomer addition. The microstructure, mechanical, self-healing, and surface morphologies of the block copolymers were thoroughly studied. Both excellent mechanical performance and self-healing capability were achieved for the block copolymers because of the interplayed physical cross-link of hard block and dynamic interaction formed by soft block in the self-assembled network. Under an optimized hard block (PHBM) weight ratio of 5%, a significant recovery of tensile strength (up to 100%) and strain at break (ca. 85%) was achieved at ambient temperature without any treatment even after complete rupture. Moreover, the simple reaction operations and well-designed monomers offer versatility in tuning the architectures and properties of the resulting block copolymers.

  15. Alignment of Fatty Acid-Derived Triblock Copolymers under Large Amplitude Oscillatory Shear

    NASA Astrophysics Data System (ADS)

    Ding, Wenyue; Wang, Shu; Kesava, Sameer; Gomez, Enrique; Robertson, Megan

    Linear ABA triblock copolymers find widespread utilization as thermoplastic elastomers (TPEs): materials which exhibit elastomeric behavior at room temperature and can be readily processed at elevated temperatures. Traditional TPEs are derived from fossil fuels; however, the finite availability of petroleum and the environmental impact of petroleum processing has led to an increased interest in developing alternative sources for polymers. Vegetable oils and their fatty acids are promising replacements for petroleum sources due to their abundance, low cost, lack of toxicity, biodegradability and ease of functionalization that provides convenient routes to polymerization. In this study, triblock copolymer TPEs were synthesized containing lauryl and stearyl acrylate, derived from fatty acids found in vegetable oils. Small-angle X-ray scattering experiments revealed highly aligned triblock copolymer morphologies after the application of large amplitude oscillatory shear. The temperature and frequency dependence of the degree of alignment was investigated. In contrast to prior studies on shear-aligned morphologies in bulk and thin film block copolymers, hexagonal close packed and face centered cubic spherical structures were observed.

  16. Self-organization of graft copolymers at surfaces, interfaces and in bulk

    SciTech Connect

    Rabeony, M.; Peiffer, D.G.; Behal, S.K.; Disko, M.; Dozier, W.D.; Thiyagarajan, P.; Lin, M.Y.

    1994-07-01

    The morphology in bulk and thin film of high-integrity graft copolymers has been investigated by small angle neutron and light scattering, neutron reflectivity, and transmission electron microscopy. The model graft copolymers are based on two chemically incompatible-blocks composed of an elastomeric polyethylacrylate backbone onto which pendant monodisperse thermoplastic polystyrene are statistically placed. Two different levels of graft corresponding to an average of 1 and 3 per chain were investigated. In the bulk phase, the low graft level shows irregular fractal-like structures while the high graft level exhibits lamellar microdomains. In thin film, ordered structures were observed also in both compositions. The interphase adhesion between the polystyrene and the polyethylacrylate microdomain was investigated by uniaxially elongating the copolymer films. The low level graft material exhibits normal behavior characteristic of filler-reinforced rubber: the isotropic scattering pattern deforms in an anisotropic manner, i.e., ellipsoid-shaped with the long axis perpendicular to the stretching direction. An ``abnormal Butterfly`` pattern was observed with the high graft level. The butterfly pattern is attributed to the deformation of the lamellar morphology of the copolymer.

  17. Block copolymer investigations

    NASA Astrophysics Data System (ADS)

    Yufa, Nataliya A.

    The research presented in this thesis deals with various aspects of block copolymers on the nanoscale: their behavior at a range of temperatures, their use as scaffolds, or for creation of chemically striped surfaces, as well as the behavior of metals on block copolymers under the influence of UV light, and the healing behavior of copolymers. Invented around the time of World War II, copolymers have been used for decades due to their macroscopic properties, such as their ability to be molded without vulcanization, and the fact that, unlike rubber, they can be recycled. In recent years, block copolymers (BCPs) have been used for lithography, as scaffolds for nano-objects, to create a magnetic hard drive, as well as in photonic and other applications. In this work we used primarily atomic force microscopy (AFM) and transmission electron microscopy (TEM), described in Chapter II, to conduct our studies. In Chapter III we demonstrate a new and general method for positioning nanoparticles within nanoscale grooves. This technique is suitable for nanodots, nanocrystals, as well as DNA. We use AFM and TEM to demonstrate selective decoration. In Chapters IV and V we use AFM and TEM to study the structure of polymer surfaces coated with metals and self-assembled monolayers. We describe how the surfaces were created, exhibit their structure on the nanoscale, and prove that their macroscopic wetting properties have been altered compared to the original polymer structures. Finally, Chapters VI and VII report out in-situ AFM studies of BCP at high temperatures, made possible only recently with the invention of air-tight high-temperature AFM imaging cells. We locate the transition between disordered films and cylinders during initial ordering. Fluctuations of existing domains leading to domain coarsening are also described, and are shown to be consistent with reptation and curvature minimization. Chapter VII deals with the healing of PS-b-PMMA following AFM-tip lithography or

  18. Thermoplastic elastomer with advanced hydrophilization and bonding performances for rapid (30 s) and easy molding of microfluidic devices.

    PubMed

    Lachaux, Julie; Alcaine, Clara; Gómez-Escoda, Blanca; Perrault, Cécile M; Duplan, David Olea; Wu, Pei-Yun Jenny; Ochoa, Iñaki; Fernandez, Luis; Mercier, Olaf; Coudreuse, Damien; Roy, Emmanuel

    2017-07-25

    One of the most important areas of research on microfluidic technologies focuses on the identification and characterisation of novel materials with enhanced properties and versatility. Here we present a fast, easy and inexpensive microstructuration method for the fabrication of novel, flexible, transparent and biocompatible microfluidic devices. Using a simple hot press, we demonstrate the rapid (30 s) production of various microfluidic prototypes embossed in a commercially available soft thermoplastic elastomer (sTPE). This styrenic block copolymer (BCP) material is as flexible as PDMS and as thermoformable as classical thermoplastics. It exhibits high fidelity of replication using SU-8 and epoxy master molds in a highly convenient low-isobar (0.4 bar) and iso-thermal process. Microfluidic devices can then be easily sealed using either a simple hot plate or even a room-temperature assembly, allowing them to sustain liquid pressures of 2 and 0.6 bar, respectively. The excellent sorption and biocompatibility properties of the microchips were validated via a standard rhodamine dye assay as well as a sensitive yeast cell-based assay. The morphology and composition of the surface area after plasma treatment for hydrophilization purposes are stable and show constant and homogenous distribution of block nanodomains (∼22° after 4 days). These domains, which are evenly distributed on the nanoscale, therefore account for the uniform and convenient surface of a "microfluidic scale device". To our knowledge, this is the first thermoplastic elastomer material that can be used for fast and reliable fabrication and assembly of microdevices while maintaining a high and stable hydrophilicity.

  19. Wear resistance of injection-molded thermoplastic denture base resins.

    PubMed

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo V J; Vallittu, Pekka K; Takahashi, Yutaka

    2016-12-01

    Objective This study investigated the wear resistance of injection-molded thermoplastic denture base resins using nanoindentation instrument. Materials and methods Six injection-molded thermoplastic denture base resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate [PMMA]) and a PMMA conventional heat-polymerized denture-based polymer control were tested. Elastic modulus, hardness, wear depth, and roughness were calculated using a nanoindentation instrument. Results Elastic modulus and hardness of the injection-molded thermoplastic denture base resins were significantly lower than those of the PMMA conventional heat-polymerized denture-based polymer. Wear depth of polycarbonate and PMMA conventional heat-polymerized denture-based polymer were significantly higher than that of other injection-molded thermoplastic denture base resins. The roughness of injection-molded thermoplastic denture base resins was significantly more than that of PMMA conventional heat-polymerized denture-based polymer after testing. Conclusions Wear resistance of injection-molded thermoplastic denture base was low compared to PMMA conventional heat-polymerized denture-based polymers.

  20. Wear resistance of injection-molded thermoplastic denture base resins

    PubMed Central

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo V. J.; Vallittu, Pekka K.; Takahashi, Yutaka

    2016-01-01

    Abstract Objective This study investigated the wear resistance of injection-molded thermoplastic denture base resins using nanoindentation instrument. Materials and methods Six injection-molded thermoplastic denture base resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate [PMMA]) and a PMMA conventional heat-polymerized denture-based polymer control were tested. Elastic modulus, hardness, wear depth, and roughness were calculated using a nanoindentation instrument. Results Elastic modulus and hardness of the injection-molded thermoplastic denture base resins were significantly lower than those of the PMMA conventional heat-polymerized denture-based polymer. Wear depth of polycarbonate and PMMA conventional heat-polymerized denture-based polymer were significantly higher than that of other injection-molded thermoplastic denture base resins. The roughness of injection-molded thermoplastic denture base resins was significantly more than that of PMMA conventional heat-polymerized denture-based polymer after testing. Conclusions Wear resistance of injection-molded thermoplastic denture base was low compared to PMMA conventional heat-polymerized denture-based polymers. PMID:28642909

  1. The use of polyurethane as an elastomer in thermoplastic microfluidic devices and the study of its creep properties.

    PubMed

    Gu, Pan; Nishida, Toshikazu; Fan, Z Hugh

    2014-02-01

    We report using polyurethane (PU) as an elastomer in microvalves integrated with thermoplastic microfluidic devices. Elastomer-based microvalves have been used in a number of applications and the elastomer often used is PDMS. Although it is a convenient material for prototyping, PDMS has been recognized to possess shortcomings such as solvent incompatibility and unfavorable manufacturability. We investigated the use of PU as an elastomer to address the challenges. A reliable method was developed to bond hybrid materials such as PU and cyclic olefin copolymer. The film thickness from 3.5 to 24.5 μm was studied to identify an appropriate thickness of PU films for desirable elasticity in microvalves. We integrated PU with thermally actuated, elastomer-based microvalves in thermoplastic devices. Valve actuations were demonstrated, and the relationship between the valve actuation time and heater power was studied. We compared PU with PDMS in terms of their microvalve performance. Valves with PDMS failed to function after two weeks since the thermal-sensitive solution evaporated through porous PDMS membrane, whereas the same valve with PU functioned properly after eight months. In addition, we evaluated the creep and creep recovery of PU, which is a common phenomenon of viscoelastic materials and is related to the long-term elastic property of PU after prolonged use.

  2. The Use of Polyurethane as an Elastomer in Thermoplastic Microfluidic Devices and the Study of its Creep Properties

    PubMed Central

    Gu, Pan; Nishida, Toshikazu; Fan, Z. Hugh

    2013-01-01

    We report using polyurethane (PU) as an elastomer in microvalves integrated with thermoplastic microfluidic devices. Elastomer-based microvalves have been used in a number of applications and the elastomer often used is polydimethylsiloxane (PDMS). Although it is a convenient material for prototyping, PDMS has been recognized to possess shortcomings such as solvent incompatibility and unfavorable manufacturability. We investigated the use of PU as an elastomer to address the challenges. A reliable method was developed to bond hybrid materials such as PU and cyclic olefin copolymer (COC). The film thickness from 3.5 to 24.5 μm was studied to identify an appropriate thickness of PU films for desirable elasticity in microvalves. We integrated PU with thermally actuated, elastomer-based microvalves in thermoplastic devices. Valve actuations were demonstrated, and the relationship between the valve actuation time and heater power was studied. We compared PU with PDMS in terms of their microvalve performance. Valves with PDMS failed to function after 2 weeks since the thermal-sensitive solution evaporated through porous PDMS membrane, whereas the same valve with PU functioned properly after 8 months. In addition, we evaluated the creep and creep recovery of PU, which is a common phenomenon of viscoelastic materials and is related to the long-term elastic property of PU after prolonged use. PMID:23868507

  3. Interfacial Modification by Copolymers: The Importance of Copolymer Microstructure

    NASA Astrophysics Data System (ADS)

    Dadmun, Mark; Eastwood, Eric

    2002-03-01

    The dispersion of nanoscale particles or domains in a polymer matrix can readily lead to nonlinear enhancement of material properties. Our research group has been examining two primary methods to improve the properties of multicomponent polymer systems: compatibilization of a blend with an interfacial modifier or improving the miscibility and properties of polymer blends with specific interactions. In this talk, the importance of specific copolymer microstructure on its ability to strengthen a biphasic interface will be discussed. Atom transfer radical polymerization has been utilized to polymerize a series of multiblock copolymers containing styrene and methyl methacrylate. This, in turn, has allowed the synthesis of a series of copolymers with careful control of the sequence distribution. Subsequent experiments that determine the interfacial strength between two polymers in the presence and absence of these copolymers has provided critical information that documents the importance of copolymer sequence distribution on its ability to strengthen a biphasic interface.

  4. Polyether/Polyester Graft Copolymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L., Jr.; Wakelyn, N.; Stoakley, D. M.; Proctor, K. M.

    1986-01-01

    Higher solvent resistance achieved along with lower melting temperature. New technique provides method of preparing copolymers with polypivalolactone segments grafted onto poly (2,6-dimethyl-phenylene oxide) backbone. Process makes strong materials with improved solvent resistance and crystalline, thermally-reversible crosslinks. Resulting graft copolymers easier to fabricate into useful articles, including thin films, sheets, fibers, foams, laminates, and moldings.

  5. High Temperature Reactive Thermoplastic Aromatic Polyimides

    DTIC Science & Technology

    1980-04-01

    incorporated into an imide containing backbone. Aromatic enyne imide copolymers VIlla-c employing 1,3- bis -(aminophenoxy) benzene VI and 2,2- bis [ 4 -(3,4...ynylene) dianiline, 4 ml of m-cresol and two drops of isoquinoline. After the diamine had dissolved, 0.9260 g (1.707 mmol) of 1,4- bis (3,4-dicarboxy...unylene) dianiline, 4 ml of freshly distilled m-crlesol and two drops of isoquinoline. After the diamine had dissolved, 0.7583 g (1.707 mmol) of 2,2- bis

  6. Polylactide-Poly(6-methyl-ε-caprolactone)-Polylactide Thermoplastic Elastomers

    SciTech Connect

    Martello, Mark T; Hillmyer, Marc A

    2012-11-14

    Amorphous ABA type block aliphatic polyesters can be useful as degradable and biorenewable thermoplastic elastomers. These materials can be prepared by sequential ring-opening transesterification polymerization (ROTEP) reactions and can exhibit a range of physical properties and morphologies. In this work a set of amorphous polylactide-poly(6-methyl-ε-caprolactone)-polylactide aliphatic polyester ABA triblock copolymers were prepared by consecutive controlled ring-opening polymerizations. Ring-opening polymerization of neat 6-methyl-ε-caprolactone in the presence of 1,4-benzenedimethanol and tin(II) octoate afforded α,ω-hydroxyl-terminated poly(6-methyl-ε-caprolactone). High conversions of 6-methyl-ε-caprolactone (>96%) afforded polymers with molar masses ranging from 12 to 98 kg mol-1, depending on monomer-to-initiator ratios, polymers with narrow, monomodal molecular weight distributions. An array of polylactide-poly(6-methyl-ε-caprolactone)-polylactide triblock copolymers with controlled molecular weights and narrow molecular weight distributions were synthesized using the telechelic poly(6-methyl-ε-caprolactone) samples as macroinitiators for the ring-opening polymerization of D,L-lactide. The morphological, thermal, and mechanical behaviors of these materials were explored. Several triblocks adopted well-ordered microphase-separated morphologies, and both hexagonally packed cylindrical and lamellar structures were observed. The Flory-Huggins interaction parameter was determined, x(T) = 61.2 T-1 - 0.1, based on the order-to-disorder transition temperatures of two symmetric triblocks using the calculated mean field theory result. The elastomeric mechanical behavior of two high molecular weight triblocks was characterized by tensile and elastic recovery experiments.

  7. Novel polymer blends with thermoplastic starch

    NASA Astrophysics Data System (ADS)

    Taghizadeh, Ata

    A new class of polymers known as "bioplastics" has emerged and is expanding rapidly. This class consists of polymers that are either bio-based or biodegradable, or both. Among these, polysaccharides, namely starch, are of great interest for several reasons. By gelatinizing starch via plasticizers, it can be processed in the same way as thermoplastic polymers with conventional processing equipment. Hence, these bio-based and biodegradable plastics, with their low source and refinery costs, as well as relatively easy processability, have made them ideal candidates for incorporation into various current plastic products. Four different plasticizers have been chosen here for gelatinization of thermoplastic starch (TPS): glycerol, sorbitol, diglycerol and polyglycerol, with the latter two being used for the first time in such a process. Two methodological categories are used. The first involves a calorimetric method (Differential Scanning Calorimetry) as well as optical microscopy; these are "static" methods where no shear is applied A wide range of starch/water/plasticizer compositions were prepared to explore the gelatinization regime for each plasticizer. The onset and conclusion gelatinization temperatures for sorbitol and glycerol were found to be in the same vicinity, while diglycerol and polyglycerol showed significantly higher transition temperatures. The higher molecular weight and viscosity of polyglycerol allow this transition to occur at an even higher temperature than with diglycerol. This is due to the increase in molecular weight and viscosity of the two new plasticizers, as well as their significant decrease in water solubility. It is demonstrated that the water/plasticizer ratio has a pronounced effect on gelatinization temperatures. When plasticizer content was held constant and water content was increased, it was found that the gelatinization temperature decreased for all the plasticizers. Meanwhile, when the water content was held constant and the

  8. Effect of chain microstructure on physical properties of olefin copolymers

    NASA Astrophysics Data System (ADS)

    Poon, Benjamin Chunman

    The effect of chain microstructure on various physical properties was studied in polyethylene and polypropylene copolymers. Adhesion of Ziegler-Natta (ZNPE) and metallocene (mPE) catalyzed ethylene-octene copolymers to polypropylene (PP) were studied by measuring the delamination toughness G of coextruded microlayers using the T-peel test. It was found that the heterogeneous ZNPE exhibited poor adhesion to polypropylene. It was proposed that the low molecular weight, highly branched ZNPE fractions migrate to the interface to form an amorphous layer. The homogeneous mPE with the same short chain branch content showed very high G. Blending ZNPE with an mPE increased G. Atomic force microscopy revealed that blending mPE into ZNPE reduced or eliminated the amorphous interfacial layer. It was hypothesized that mPE increased miscibility of low molecular weight, highly branched fractions of ZNPE and prevented their segregation at the interface. The solid state structure and properties of homogeneous propylene-octene copolymers were examined. Based on the combined observations from melting behavior, dynamic mechanical response, morphology with primarily atomic force microscopy, X-ray diffraction, and tensile deformation, a classification scheme with 4 distinct categories is proposed. The homopolymer with 60 wt% crystallinity constitutes Type IV. It is characterized by large alpha-positive spherulite. Copolymers with up to 5 mol% octene, with at least 35 wt% crystallinity, are classified as Type III. They crystallize as alpha-positive spherulites that are smaller than the homopolymer. Both Type IV and Type III materials exhibit thermoplastic behavior. Copolymers classified as Type II have between 5 and 10 mol% octene with crystallinity in the range of 20--35%. Type II materials have smaller impinging spherulites than Type III copolymers and they are negative. The materials in this category have plastomeric behavior. Type I copolymers have more than 10 mol% octene and less

  9. Improved Thermoplastic/Iron-Particle Transformer Cores

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.; Bryant, Robert G.; Namkung, Min

    2004-01-01

    A method of fabricating improved transformer cores from composites of thermoplastic matrices and iron-particles has been invented. Relative to commercially available laminated-iron-alloy transformer cores, the cores fabricated by this method weigh less and are less expensive. Relative to prior polymer-matrix/ iron-particle composite-material transformer cores, the cores fabricated by this method can be made mechanically stronger and more magnetically permeable. In addition, whereas some prior cores have exhibited significant eddy-current losses, the cores fabricated by this method exhibit very small eddy-current losses. The cores made by this method can be expected to be attractive for use in diverse applications, including high-signal-to-noise transformers, stepping motors, and high-frequency ignition coils. The present method is a product of an experimental study of the relationships among fabrication conditions, final densities of iron particles, and mechanical and electromagnetic properties of fabricated cores. Among the fabrication conditions investigated were molding pressures (83, 104, and 131 MPa), and molding temperatures (250, 300, and 350 C). Each block of core material was made by uniaxial-compression molding, at the applicable pressure/temperature combination, of a mixture of 2 weight percent of LaRC (or equivalent high-temperature soluble thermoplastic adhesive) with 98 weight percent of approximately spherical iron particles having diameters in the micron range. Each molded block was cut into square cross-section rods that were used as core specimens in mechanical and electromagnetic tests. Some of the core specimens were annealed at 900 C and cooled slowly before testing. For comparison, a low-carbon-steel core was also tested. The results of the tests showed that density, hardness, and rupture strength generally increased with molding pressure and temperature, though the correlation was rather weak. The weakness of the correlation was attributed to

  10. Chemical Modification and Structure-property Relationships of Acrylic and Ionomeric Thermoplastic Elastomer Gels

    NASA Astrophysics Data System (ADS)

    Vargantwar, Pruthesh Hariharrao

    Block copolymers (BCs) have remained at the forefront of materials research due to their versatility in applications ranging from hot-melt/pressure-sensitive adhesives and impact modifiers to compatibilizing agents and vibration-dampening/nanotemplating media. Of particular interest are macromolecules composed of two or more chemically dissimilar blocks covalently linked together to form triblock or pentablock copolymers. If the blocks are sufficiently incompatible and the copolymer behaves as a thermoplastic elastomer, the molecules can spontaneously self-assemble to form nanostructured materials that exhibit shape memory due to the formation of a supramolecular network. The BCs of these types are termed as conventional. When BCs contain blocks having ionic moieties such as sulfonic acid groups, they are termed as block ionomers. Designing new systems based on either conventional or ionic BCs, characterizing their structure-property relationships and later using them as electroacive polymers form the essential objectives of this work. Electroactive polymers (EAPs) exhibit electromechanical actuation when stimulated by an external electric field. In the first part of this work, it is shown that BCs resolve some of the outstanding problems presently encountered in the design of two different classes of EAP actuators: dielectric elastomers (DEs) and ionic polymer metal composites (IPMCs). All-acrylic triblock copolymer gels used as DEs actuate with high efficacy without any requirement of mechanical prestrain and, thus, eliminate the need for bulky and heavy hardware essential with prestrained dielectric actuators, as well as material problems associated with stress relaxation. The dependence of actuation behavior on gel morphology as evaluated from mechanical and microstructure studies is observed. In the case of IPMCs, ionic BCs employed in this study greatly facilitate processing compared to other contenders such as NafionRTM, which is commonly used in this class

  11. Second generation copolymers for EOR

    SciTech Connect

    McCormick, C.L.

    1988-05-01

    In this report, the authors review four types of acrylamide-based copolymers with distinctly different dilute solutions and rheological behavior. Each of these ''second generation'' systems possesses characteristics which, in theory, should be superior to conventional polymers under certain operational conditions. Type I copolymers are prepared from acrylamide (AM) and sodium-3-acrylamido-3-methylbutanoate (NaAMB). The high molecular weight, viscosity maintenance, and phase stability in the presence of divalent ions make these copolymers especially attractive for mobility control in EOR. Type II copolymers address the problems of entrapment, pore clogging, and shear degradation often encountered with ultrahigh molecular weight copolymers. The copolymers of this type are lower molecular weight than Type 1 but associate in a cooperative manner in semi-dilute solutions to enhance solution viscoscity. In this report, the authors discuss associative polymers of acrylamide/N-alkyl acrylamides which contain low mole percentages of C/sub 8/, C/sub 10/, or C/sub 12/ comonomers. In practice, a third charged comonomer such as carboxylated or sulfonated one, might be necessary to reduce adsorption to reservoir rock. Type III systems are relatively low molecular weight and hyrophibically modified in order to bring about intramolecular micelle-like association in aqueous solution. The aqueous solutions are non-viscous; viscosification occurs upon solubilization of hydrocarbons in the hydrophobic domains. Copolymers of acrylamide with N-propyl diacetone acrylamide are examples of Type III.

  12. A Thermoplasticity Model for Oil Shale

    NASA Astrophysics Data System (ADS)

    White, Joshua A.; Burnham, Alan K.; Camp, David W.

    2017-03-01

    Several regions of the world have abundant oil shale resources, but accessing this energy supply poses a number of challenges. One particular difficulty is the thermomechanical behavior of the material. When heated to sufficient temperatures, thermal conversion of kerogen to oil, gas, and other products takes place. This alteration of microstructure leads to a complex geomechanical response. In this work, we develop a thermoplasticity model for oil shale. The model is based on critical state plasticity, a framework often used for modeling clays and soft rocks. The model described here allows for both hardening due to mechanical deformation and softening due to thermal processes. In particular, the preconsolidation pressure—defining the onset of plastic volumetric compaction—is controlled by a state variable representing the kerogen content of the material. As kerogen is converted to other phases, the material weakens and plastic compaction begins. We calibrate and compare the proposed model to a suite of high-temperature uniaxial and triaxial experiments on core samples from a pilot in situ processing operation in the Green River Formation. We also describe avenues for future work to improve understanding and prediction of the geomechanical behavior of oil shale operations.

  13. Accelerated Strength Testing of Thermoplastic Composites

    NASA Technical Reports Server (NTRS)

    Reeder, J. R.; Allen, D. H.; Bradley, W. L.

    1998-01-01

    Constant ramp strength tests on unidirectional thermoplastic composite specimens oriented in the 90 deg. direction were conducted at constant temperatures ranging from 149 C to 232 C. Ramp rates spanning 5 orders of magnitude were tested so that failures occurred in the range from 0.5 sec. to 24 hrs. (0.5 to 100,000 MPa/sec). Below 204 C, time-temperature superposition held allowing strength at longer times to be estimated from strength tests at shorter times but higher temperatures. The data indicated that a 50% drop in strength might be expected for this material when the test time is increased by 9 orders of magnitude. The shift factors derived from compliance data applied well to the strength results. To explain the link between compliance and strength, a viscoelastic fracture model was investigated. The model, which used compliance as input, was found to fit the strength data only if the critical fracture energy was allowed to vary with temperature reduced stress rate. This variation in the critical parameter severely limits its use in developing a robust time-dependent strength model. The significance of this research is therefore seen as providing both the indication that a more versatile acceleration method for strength can be developed and the evidence that such a method is needed.

  14. Photochromic Inorganic/Organic Thermoplastic Elastomers.

    PubMed

    Zhang, Jiuyang; Li, Jing; Huo, Mengmeng; Li, Naixu; Zhou, Jiancheng; Li, Tuoqi; Jiang, Jing

    2017-08-01

    Photochromic materials are an important class of "smart materials" and are broadly utilized in technological devices. However, most photochromic materials reported so far are composed of inorganic compounds that are challenging to process and suffer from poor mechanical performance, severely limiting their applications in various markets. In this paper, inorganic photochromic tungsten trioxide (WO3 ) nanocrystals are conveniently grafted with polymers to hurdle the deficiency in processability and mechanical properties. This new type of photochromic material can be thermally processed into desired geometries like disks and dog-bone specimens. Fully reversible photochromic response under UV light is also achieved for WO3 -graft polymers, exhibiting tunable response rate, outperforming the pristine WO3 nanocrystals. Notably, the resulted graft polymers show extraordinary mechanical performance with excellent ductility (≈800% breaking strain) and relatively high breaking strength (≈2 MPa). These discoveries elucidate an effective pathway to design smart inorganic/organic hybrid thermoplastic elastomers endowed with outstanding photochromic and mechanical properties as well as exceptional processability. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Relaxation in bolted thermoplastic composite joints

    NASA Astrophysics Data System (ADS)

    Horn, Walter J.; Schmitt, Ron R.

    1993-04-01

    The long term effects of the relaxation of fastener clamp-up force on the strength of mechanically fastened joints were investigated through a test program of single-shear joints. Static tests of two graphite/thermoplastic composite materials, IM6/KIII and IM8/APC (HTA), established joint bearing strength as a function of clamp-up force for both protruding head and countersunk fasteners. Test results indicated that joint bearing strength of both materials increased by as much as twenty-eight percent over the range of clamp-up force. Short-term fastener clamp-up force relaxation was monitored with special bolt force sensor washers. The results of these tests indicated that the fastener clamp-up force decreased an average of six percent from the initial value during the short-term room temperature tests and was projected to be as high as sixteen percent after 100,000 hours of service. The relaxation rate at the elevated temperature of 250F was projected to be as high as thirty-seven percent for HTA and sixty percent for KIII after 100,000 hours of service. It was concluded that the short-term relaxation of the clamp-up force did not significantly lower the bearing strength of either material, but an extended exposure to 250F could affect the bearing strength.

  16. Development and characterization of hybrid thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Karkhanis, Priyanka Chandrashekhar

    This work is aimed at studying the possibility of using interply hybrid woven thermoplastic semi-pregs in secondary structures in aircrafts at TenCate Advanced Composites, Netherlands and Purdue University. Three different interply hybrids were designed from combination of Cetex(c) carbon-PPS semi-preg, Owen corning's woven glass with PPS sheets and discontinuous chopped Cetex(c) carbon-PPS semi-preg to get desired flexural, out of plane and bearing properties. The design calculations are done based on classical laminate theory and the selection of materials to be used with carbon-PPS was done based on cost and availability. The Hybrid laminate performances are analyzed and compared to the conventional Cetex (c) Carbon-PPS semi-preg laminates. Observations are reported on three point bend test (European standard 2562), four point bend test(ASTM D6415-99) and bearing test (Airbus standards AITM 1-0009) for the laminates and it was found that hybrid laminates show a reduction of 5-10% in bending stiffness, 20-40% reduction in out-of-plane strength and 2-5%reduction in bearing with a cost reduction of 20-30%. The research identifies and documents the different factors responsible for failures and reduction in strength in the Hybrids.

  17. Thermoplastic Polyurethanes with Isosorbide Chain Extender

    SciTech Connect

    Javni, Ivan; Bilic, Olivera; Bilic, Nikola; Petrovic, Zoran; Eastwood, Eric; Zhang, Fan; Ilavsky, Jan

    2015-12-15

    Isosorbide, a renewable diol derived from starch, was used alone or in combination with butane diol (BD) as the chain extender in two series of thermoplastic polyurethanes (TPU) with 50 and 70% polytetramethylene ether glycol (PTMEG) soft segment concentration (SSC), respectively. In the synthesized TPUs, the hard segment composition was systematically varied in both series following BD/isosorbide molar ratios of 100 : 0; 75 : 25; 50 : 50; 25 : 75, and 0 : 100 to examine in detail the effect of chain extenders on properties of segmented polyurethane elastomers with different morphologies. We found that polyurethanes with 50% SSC were hard elastomers with Shore D hardness of around 50, which is consistent with assumed co-continuous morphology. Polymers with 70% SSC displayed lower Shore A hardness of 74–79 (Shore D around 25) as a result of globular hard domains dispersed in the soft matrix. Insertion of isosorbide increased rigidity, melting point and glass transition temperature of hard segments and tensile strength of elastomers with 50% SSC. These effects were weaker or non-existent in 70% SSC series due to the short hard segments and low content of isosorbide. We also found that the thermal stability was lowered by increasing isosorbide content in both series.

  18. Development of thermoplastic composite aircraft structures

    NASA Technical Reports Server (NTRS)

    Renieri, Michael P.; Burpo, Steven J.; Roundy, Lance M.; Todd, Stephanie A.; Kim, H. J.

    1992-01-01

    Efforts focused on the use of thermoplastic composite materials in the development of structural details associated with an advanced fighter fuselage section with applicability to transport design. In support of these designs, mechanics developments were conducted in two areas. First, a dissipative strain energy approach to material characterization and failure prediction, developed at the Naval Research Laboratory, was evaluated as a design/analysis tool. Second, a finite element formulation for thick composites was developed and incorporated into a lug analysis method which incorporates pin bending effects. Manufacturing concepts were developed for an upper fuel cell cover. A detailed trade study produced two promising concepts: fiber placement and single-step diaphragm forming. Based on the innovative design/manufacturing concepts for the fuselage section primary structure, elements were designed, fabricated, and structurally tested. These elements focused on key issues such as thick composite lugs and low cost forming of fastenerless, stiffener/moldine concepts. Manufacturing techniques included autoclave consolidation, single diaphragm consolidation (SDCC) and roll-forming.

  19. Renewable Aliphatic Polyester Block Polymer Thermoplastic Elastomers

    NASA Astrophysics Data System (ADS)

    Martello, Mark Thomas

    The performance of thermoplastic elastomers is predicated on their ability to form mechanically tough physically crosslinked elastomeric networks at low temperatures and be able to flow at elevated temperatures. This dissertation focuses on renewable aliphatic polyester block polymers with amorphous polylactide (PLA) and their performance as TPEs. The goal of this work was to enhance the mechanical toughness of PLA containing TPEs; fundamental properties ranging from chemical composition and phase behavior, molecular architecture and melt processability, to melt polymerization strategies were investigated. ABA triblock polymers with PLA end-blocks and rubbery mid-blocks from substituted lactones comprised of poly(6-methyl-epsilon-caprolactone)(PMCL), poly(delta-decalactone), and poly(epsilon-decalactone)(PDL) were produced by sequential ring-opening polymerizations in the bulk. The bulk microstructure of symmetric PLA-PMCL-PLA and PLA-PDL-PLA triblock polymers formed long-range ordered morphologies and the interaction parameter of the repeat units was determined. High molar mass triblocks exhibited elastomeric behavior with good tensile strengths and high elongations. Small triblocks were coupled to produced (PLA-PDL-PLA)n multiblock polymers with high molar mass and accessible order-disorder transitions allowing for melt processing via injection molding. The mechanical toughness of the multiblocks was comparable to the high molar mass triblocks. The controlled polymerization of renewable delta-decalactone was accomplished with an organocatalyst at low temperatures in the bulk to maximize the equilibrium conversion of the monomer.

  20. Interlaminar interaction in paper thermoplastic laminate composites

    NASA Astrophysics Data System (ADS)

    Prambauer, M.; Paulik, C.; Burgstaller, C.

    2016-07-01

    Bio-based composites are a research topic since several decades, which aims for sustainable and durable materials. In the scope of this research, many different sources for biobased reinforcements have been investigated. Typical issues associated with the use of such are property variations due to cultivation area and climate, besides the influences of the type, pretreatment and fibre geometry. Another issue can be the availability of such natural fibres. Due to these reasons, we started using paper sheets as reinforcements in laminate composites with thermoplastic materials. In preliminary studies with polypropylene composites, we found good mechanical properties, even higher than could be expected by estimating the composite properties from the constituents by applying simple rule of mixtures type models. We suspect, besides some effect of paper compaction, interlaminar effects to be the reason for this. Therefore, the aim of this work is to investigate the effects of the interfacial interaction on the different paper laminate properties due to different matrix polymers. For this work, we used polypropylene, polyamide 6 and 12 as well as polystyrene. Composites were produced via compression moulding and samples for mechanical testing and density evaluation were cut from the moulded plates. The results from mechanical tests show, that there is a reinforcing effect, regardless of matrix polymer used. Simple rule of mixtures evaluations show, that the different matrices exhibit different degrees of interaction, based on their chemical structure. In addition, also influences due to processing were found.

  1. Materials for Heated Head Automated Thermoplastic Tape Placement

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Kinney, Megan C.; Cano, Roberto J.; Grimsley, Brian W.

    2012-01-01

    NASA Langley Research Center (LaRC) is currently pursuing multiple paths to develop out of autoclave (OOA) polymeric composite materials and processes. Polymeric composite materials development includes the synthesis of new and/or modified thermosetting and thermoplastic matrix resins designed for specific OOA processes. OOA processes currently under investigation include vacuum bag only (VBO) prepreg/composite fabrication, resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM) and heated head automated thermoplastic tape placement (HHATP). This paper will discuss the NASA Langley HHATP facility and capabilities and recent work on characterizing thermoplastic tape quality and requirements for quality part production. Samples of three distinct versions of APC-2 (AS4/PEEK) thermoplastic dry tape were obtained from two materials vendors, TENCATE, Inc. and CYTEC Engineered Materials** (standard grade and an experimental batch). Random specimens were taken from each of these samples and subjected to photo-microscopy and surface profilometry. The CYTEC standard grade of APC-2 tape had the most voids and splits and the highest surface roughness and/or waviness. Since the APC-2 tape is composed of a thermoplastic matrix, it offers the flexibility of reprocessing to improve quality, and thereby improve final quality of HHATP laminates. Discussions will also include potential research areas and future work that is required to advance the state of the art in the HHATP process for composite fabrication.

  2. Non-invasive primate head restraint using thermoplastic masks.

    PubMed

    Drucker, Caroline B; Carlson, Monica L; Toda, Koji; DeWind, Nicholas K; Platt, Michael L

    2015-09-30

    The success of many neuroscientific studies depends upon adequate head fixation of awake, behaving animals. Typically, this is achieved by surgically affixing a head-restraint prosthesis to the skull. Here we report the use of thermoplastic masks to non-invasively restrain monkeys' heads. Mesh thermoplastic sheets become pliable when heated and can then be molded to an individual monkey's head. After cooling, the custom mask retains this shape indefinitely for day-to-day use. We successfully trained rhesus macaques (Macaca mulatta) to perform cognitive tasks while wearing thermoplastic masks. Using these masks, we achieved a level of head stability sufficient for high-resolution eye-tracking and intracranial electrophysiology. Compared with traditional head-posts, we find that thermoplastic masks perform at least as well during infrared eye-tracking and single-neuron recordings, allow for clearer magnetic resonance image acquisition, enable freer placement of a transcranial magnetic stimulation coil, and impose lower financial and time costs on the lab. We conclude that thermoplastic masks are a viable non-invasive form of primate head restraint that enable a wide range of neuroscientific experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Non-invasive primate head restraint using thermoplastic masks

    PubMed Central

    Drucker, Caroline B.; Carlson, Monica L.; Toda, Koji; DeWind, Nicholas K.; Platt, Michael L.

    2015-01-01

    Background The success of many neuroscientific studies depends upon adequate head fixation of awake, behaving animals. Typically, this is achieved by surgically affixing a head-restraint prosthesis to the skull. New Method Here we report the use of thermoplastic masks to non-invasively restrain monkeys’ heads. Mesh thermoplastic sheets become pliable when heated and can then be molded to an individual monkey’s head. After cooling, the custom mask retains this shape indefinitely for day-to-day use. Results We successfully trained rhesus macaques (Macaca mulatta) to perform cognitive tasks while wearing thermoplastic masks. Using these masks, we achieved a level of head stability sufficient for high-resolution eye-tracking and intracranial electrophysiology. Comparison with Existing Method Compared with traditional head-posts, we find that thermoplastic masks perform at least as well during infrared eye-tracking and single-neuron recordings, allow for clearer magnetic resonance image acquisition, enable freer placement of a transcranial magnetic stimulation coil, and impose lower financial and time costs on the lab. Conclusions We conclude that thermoplastic masks are a viable non-invasive form of primate head restraint that enable a wide range of neuroscientific experiments. PMID:26112334

  4. Analytical Prediction of Forming Limits for Thermoplastic Tubes

    NASA Astrophysics Data System (ADS)

    Azhikannickal, Elizabeth; Jain, Mukesh K.

    2005-08-01

    Commodity thermoplastics such as polypropylene and polyethylene are gaining more attention from the automotive industries for applications requiring weight and cost savings. In order to assess the feasibility of employing thermoplastic tubes for subsequent forming into automotive structural components, first an establishment of the forming limits (or the forming limit diagram) for these materials is required. An analytical model, which is able to predict the forming limits for thermoplastic tubes, is useful from the perspective of examining the effect of material properties on the forming of a given shape without numerous experimental forming trials. Knowledge of the forming limits for these materials is also useful in die design as well as process control. Since thermoplastics such as polypropylene are temperature and strain rate dependent, the proposed analytical model would be able to predict the effect of temperature and strain rate on the resulting forming limits for the tube along various loading paths. Preliminary results from the model indicate that thermoplastic tubes formed at elevated temperature undergo larger strains in both the hoop and axial directions of the tube prior to localized necking.

  5. Thermoplastic Micro-Forming of Bulk Metallic Glasses: A Review

    NASA Astrophysics Data System (ADS)

    Li, Ning; Chen, Wen; Liu, Lin

    2016-04-01

    Bulk metallic glasses are a fascinating class of metallic alloys with an isotropic amorphous structure that is rapidly quenched from liquid melts. The absence of a crystalline micro-structure endows them with a portfolio of properties such as high strength, high elasticity, and excellent corrosion resistance. Whereas the limited plasticity and hence poor workability at ambient temperature impede the structural application of bulk metallic glasses, the unique superplasticity within the supercooled liquid region opens an alternative window of so-called thermoplastic forming, which allows precise and versatile net-shaping of complex geometries on length scales ranging from nanometers to centimeters that were previously unachievable with conventional crystalline metal processing. Thermoplastic forming not only breaks through the bottleneck of the manufacture of bulk metallic glasses at ambient temperature but also offers an alluring prospect in micro-engineering applications. This paper comprehensively reviews some pivotal aspects of bulk metallic glasses during thermoplastic micro-forming, including an in-depth understanding of the crystallization kinetics of bulk metallic glasses and the thermoplastic processing time window, the thermoplastic forming map that clarifies the relationship between the flow characteristics and the formability, the interfacial friction in micro-forming and novel forming methods to improve the formability, and the potential applications of the hot-embossed micro-patterns/components.

  6. Initiation of shape-memory effect by inductive heating of magnetic nanoparticles in thermoplastic polymers

    PubMed Central

    Mohr, R.; Kratz, K.; Weigel, T.; Lucka-Gabor, M.; Moneke, M.; Lendlein, A.

    2006-01-01

    In shape-memory polymers, changes in shape are mostly induced by heating, and exceeding a specific switching temperature, Tswitch. If polymers cannot be warmed up by heat transfer using a hot liquid or gaseous medium, noncontact triggering will be required. In this article, the magnetically induced shape-memory effect of composites from magnetic nanoparticles and thermoplastic shape-memory polymers is introduced. A polyetherurethane (TFX) and a biodegradable multiblock copolymer (PDC) with poly(p-dioxanone) as hard segment and poly(ε-caprolactone) as soft segment were investigated as matrix component. Nanoparticles consisting of an iron(III)oxide core in a silica matrix could be processed into both polymers. A homogeneous particle distribution in TFX could be shown. Compounds have suitable elastic and thermal properties for the shape-memory functionalization. Temporary shapes of TFX compounds were obtained by elongating at increased temperature and subsequent cooling under constant stress. Cold-drawing of PDC compounds at 25°C resulted in temporary fixation of the mechanical deformation by 50–60%. The shape-memory effect of both composite systems could be induced by inductive heating in an alternating magnetic field (f = 258 kHz; H = 30 kA·m−1). The maximum temperatures achievable by inductive heating in a specific magnetic field depend on sample geometry and nanoparticle content. Shape recovery rates of composites resulting from magnetic triggering are comparable to those obtained by increasing the environmental temperature. PMID:16537442

  7. Thickness and fit of mouthguards adjusted by notching thermoplastic sheets under different heating conditions.

    PubMed

    Mizuhashi, Fumi; Koide, Kaoru; Takahashi, Mutsumi

    2015-08-01

    This study examines the thickness and fit of mouthguards by notching thermoplastic copolymer ethylene vinyl acetate (EVA) sheets and then heating them to various degrees. The material used was a 3.8-mm-thick sports mouthguard. Notches with a length of 90 and 80 mm were cut into an EVA sheet 20 mm from the anterior and posterior margins and 15 mm from the right and left margins, respectively, and the sheet was compared with the original. The sheets were formed using a vacuum former when the sheets were heated until they hung 1.5, 2.0, 2.5, and 3.0 cm from the baseline. We measured the thickness and fit of the mouthguard at the central incisor and first molar. Differences in thickness and fit according to the measurement parts, sheet type, and heating conditions were analyzed by three-way anova. The measurement parts and sheet type significantly differed (P < 0.01), and the notched sheet maintained the required thickness. Fit differed among the measurement parts and by heating conditions (P < 0.01), but was not affected by the notching. The mouthguard fit was optimal when the sheets were heated to a hanging distance of 3.0 cm. These results suggest that the thickness and fit of the EVA sheet could be maintained by notching and heating the sheet to a hanging distance of 3.0 cm. These findings could be useful for fabricating appropriate mouthguards.

  8. Green technology for conversion of food scraps to biodegradable thermoplastic polyhydroxyalkanoates.

    PubMed

    Du, Guocheng; Yu, Jian

    2002-12-15

    A new technology is developed and demonstrated that couples anaerobic digestion of food scraps with production of biodegradable thermoplastics, polyhydroxyalkanoates (PHAs). The food wastes were digested in an anaerobic reactor producing four major organic acids. The concentrations of acetic, propionic, butyric, and lactic acids reached 5.5, 1.8, 27.4, and 32.7 g/L, respectively. The fermentative acids were transferred through membranes via molecule diffusion into an air-bubbling reactor where the acids were utilized to produce PHAs in an enriched culture of Ralstonia eutropha. With a silicone rubber membrane, butyric acid and small amounts of acetic and propionic acids were transferred and used, producing a homopolymer PHA, poly(3-hydroxybutyrate). The dry cell weight and PHA content reached 11.3 g/L and 60.2% (w/w), respectively. With a dialysis membrane, the mass transfer rates of fermentative acids were enhanced, and the PHA production was significantly improved. The dry cell weight and its PHA content reached 22.7 g/L and 72.6% (w/w), respectively. The formed PHA was a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (HV) with 2.8 mol % HV monomer unit. The polymer content (72.6% of dry cell mass) reported in this study is the highest one obtained from organic wastes and is comparable with the PHA content from pure glucose fermentation.

  9. Effects of Compression and Filler Particle Coating on the Electrical Conductivity of Thermoplastic Elastomer Composites

    NASA Astrophysics Data System (ADS)

    Albers, Willem M.; Karttunen, Mikko; Wikström, Lisa; Vilkman, Taisto

    2013-10-01

    Elastomeric polymers can be filled with metallic micro- or nanoparticles to obtain electrical conductivity, in which the conductivity is largely determined by the intrinsic conductivity of and contact resistance between the particles. Electrons will flow through the material effectively when the percolation threshold for near-neighbor contacts is exceeded and sufficiently close contacts between the filler particles are realized for electron tunneling to occur. Silver-coated glass microparticles of two types (fibers and spheres) were used as fillers in a thermoplastic elastomer composite based on styrene-ethylene-butylene-styrene copolymer, and the direct-current (DC) resistance and radiofrequency impedance were significantly reduced by coating the filler particles with octadecylmercaptan. Not only was the resistance reduced but also the atypical positive piezoresistivity effect observed in these elastomers was strongly reduced, such that resistivity values below 0.01 Ω cm were obtained for compression ratios up to 20%. In the DC measurements, an additional decrease of resistivity was obtained by inclusion of π-extended aromatic compounds, such as diphenylhexatriene. Some qualitative theories are presented to illuminate the possible mechanisms of action of these surface coatings on the piezoresistivity.

  10. Highly hydrophobic electrospun fiber mats from polyisobutylene-based thermoplastic elastomers.

    PubMed

    Lim, Goy Teck; Puskas, Judit E; Reneker, Darrell H; Jákli, Antal; Horton, Walter E

    2011-05-09

    This paper is the first report of electrospinning neat polyisobutylene-based thermoplastic elastomers. Two generations of these materials are investigated: a linear poly(styrene-b-isobutylene-b-styrene) (L_SIBS) triblock copolymer and a dendritic poly(isobutylene-b-p-methylstyrene) (D_IB-MS), also a candidate for biomedical applications. Cross-polarized optical microscopy shows birefringence, indicating orientation in the electrospun fibers, which undergo large elongation and shear during electrospinning. In contrast to the circular cross section of L_SIBS fibers, D_IB-MS yields dumbbell-shaped fiber cross sections for the combination of processing conditions, molecular weight, and architecture. Hydrophobic surfaces with a water contact angle as high as 146 ± 3° were obtained with D_IB-MS that had the noncircular fiber cross section and a hierarchical arrangement of nano- to micrometer-sized fibers in the mat. These highly water repellent fiber mats were found to serve as an excellent scaffold for bovine chondrocytes to produce cartilage tissue.

  11. Thermoplastic elastomer gels: an advanced substrate for microfluidic chemical analysis systems.

    PubMed

    Sudarsan, Arjun P; Wang, Jian; Ugaz, Victor M

    2005-08-15

    We demonstrate the use of thermoplastic elastomer gels as advanced substrates for construction of complex microfluidic networks suitable for use in miniaturized chemical analysis systems. These gels are synthesized by combining inexpensive polystyrene-(polyethylene/polybutylene)-polystyrene triblock copolymers with a hydrocarbon extender oil for which the ethylene/butylene midblocks are selectively miscible. The insoluble styrene end blocks phase separate into localized nanodomains, resulting in the formation of an optically transparent, viscoelastic, and biocompatible gel network that is melt-processable at temperatures in the vicinity of 100 degrees C. This unique combination of properties allows microfluidic channels to be fabricated in a matter of minutes by simply making impressions of the negative relief structures on heated master molds. Melt processability allows multiple impressions to be made against different masters to construct complex geometries incorporating multi-height features within the same microchannel. Intricate interconnected multilayered structures are also easily fabricated owing to the ability to bond and seal multiple layers by briefly heating the material at the bond interface. Thermal and mechanical properties are tunable over a wide range through proper selection of gel composition.

  12. A drug-in-adhesive matrix based on thermoplastic elastomer: evaluation of percutaneous absorption, adhesion, and skin irritation.

    PubMed

    Wang, ChengXiao; Liu, Ran; Tang, XiuZhen; Han, Wei

    2012-12-01

    A novel drug-in-adhesive matrix was designed and prepared. A thermoplastic elastomer, styrene-isoprene-styrene (SIS) block copolymer, in combination with tackifying resin and plasticizer, was employed to compose the matrix. Capsaicin was selected as the model drug. The drug percutaneous absorption, adhesion properties, and skin irritation were investigated. The results suggested that the diffusion through SIS matrix was the rate-limiting step of capsaicin percutaneous absorption. [SI] content in SIS and SIS proportions put important effects on drug penetration and adhesion properties. The chemical enhancers had strong interactions with the matrix and gave small effect on enhancement of drug skin permeation. The in vivo absorption of samples showed low drug plasma peaks and a steady and constant plasma level for a long period. These results suggested that the possible side effects of drug were attenuated, and the pharmacological effects were enhanced with an extended therapeutic period after application of SIS matrix. The significant differences in pharmacokinetic parameters produced by different formulations demonstrated the influences of SIS copolymer on drug penetrability. Furthermore, the result of skin toxicity test showed that no skin irritation occurred in guinea pig skin after transdermal administration of formulations.

  13. A high throughput, controllable and environmentally benign fabrication process of thermoplastic nanofibers

    USDA-ARS?s Scientific Manuscript database

    Continuous and uniform yarns of thermoplastic nanofibers were prepared via direct melt extrusion of immiscible blends of thermoplastic polymers with CAB and subsequent extraction removal of CAB. Ratios of thermoplastic/sacrificial polymers, melt viscosity, and interfacial tensions affect the formati...

  14. Thermoplastic starch-nanohybrid films with polyhedral oligomeric silsesquioxane.

    PubMed

    Martinez-Pardo, I; Shanks, Robert A; Adhikari, Benu; Adhikari, Raju

    2017-10-01

    Thermoplastic starch forms packaging films that have low gas permeability, but they are more permeable to water vapour and they are attacked by water. Our approach was to create surface and internal localised hydrophobicity using added reactive nano-materials to form nano-silica hybrids with emphasis on enhancing surface water resistance. Functionalization was via epoxy-POS, that were further linked to hydrophobic erucamide or an amphiphilic poly(oxyethylene-co-oxypropylene) mono-amine. High amylose thermoplastic starch was combined with mono-functionalised hepta-isobutyl polyhedral oligomeric silsesquioxane (POS). POS modified thermoplastic starch increased water resistance of TPS film. Wettability kinetics was a function of two distinct mechanisms each with independent linear behaviour. Surface water resistance increased and is proposed to be due to preferential location of the POS derivatives at the surface with associated increase of hydrophobicity due a surface change. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Nanocellular thermoplastic foam and process for making the same

    SciTech Connect

    Zhu, Lingbo; Costeux, Stephane; Patankar, Kshitish A.; Moore, Jonathan D.

    2015-09-29

    Prepare a thermoplastic polymer foam having a porosity of 70% or more and at least one of: (i) an average cell size of 200 nanometers or less; and (ii) a nucleation density of at least 1.times.1015 effective nucleation sites per cubic centimeter of foamable polymer composition not including blowing agent using a foamable polymer composition containing a thermoplastic polymer selected from styrenic polymer and (meth)acrylic polymers, a blowing agent comprising at least 20 mole-percent carbon dioxide based on moles of blowing agent and an additive having a Total Hansen Solubility Parameter that differs from that of carbon dioxide by less than 2 and that is present at a concentration of 0.01 to 1.5 weight parts per hundred weight parts thermoplastic polymer.

  16. Preparation of polypropylene thermoplastic container via thermoforming process

    NASA Astrophysics Data System (ADS)

    Ruqiyah Nik Hassan, Nik; Amira Mohd Ghazali, Farah; Aziz Jaafar, Abdul; Mazni Ismail, Noor

    2016-02-01

    In this study, plastic containers made of polypropylene (PP) sheets were fabricated via vacuum thermoforming. Thermoforming is a process used in fabricating plastic parts by changing flat thermoplastic sheet to three dimensional shapes. In preparing these thermoplastic containers, the design and fabrication of mould were first done by using Catia V5 software and CNC milling machine, respectively. The thermoforming process was then performed at various temperatures ranging from 160°C until 200°C on the PP sheet to form the container. From the experiment, it can be suggested that the outcomes of final thermoplastic containers are significantly depends on temperature control during thermoforming process and also the vent holes design of the mould.

  17. Aliphatic-Aromatic Heterocyclics as Potential Thermoplastics for Composite Matrices

    NASA Technical Reports Server (NTRS)

    Delano, C. B.; Kiskiras, C. J.

    1984-01-01

    The successful development of impact- and solvent-resistant thermoplastic systems for glass graphite composites is particularly attractive because of the demonstrated streamlined manufacturability of such composites. Hypothetically, thermoplastics only require simple heating and cooling cycles for component manufacture, whereas thermosets require precise, and possibly extended heating schedules which must be consistent with the cure chemistry. The sensitivity of the majority of existing thermoplastics to aircraft fluids and other solvents preempts their serious consideration in aircraft components. This is the basic reason that Acurex proposed insolubility in common solvents as the starting point. The target properties are summarized as follows: (1) prepreg properties (use of conventional prepregging equipment, 6+ months shelf stability, processability, and thermoformability); and (2) composite properties (-54 C to 93 C capability, good mechanical properties, good environmental properties, and impact resistance).

  18. Process for preparing solvent resistant, thermoplastic aromatic poly(imidesulfone)

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.; Yamaki, D. A. (Inventor)

    1984-01-01

    A process for preparing a thermoplastic poly(midesulfone) is disclosed. This resulting material has thermoplastic properties which are generally associated with polysulfones but not polyimides, and solvent resistant which is generally associated with polyimides but not polysulfones. This system is processable in the 250 to 350 C range for molding, adhesive and laminating applications. This unique thermoplastic poly(imidesulfone) is obtained by incorporating an aromatic sulfone moiety into the backbone of an aromatic linear polyimide by dissolving a quantity of a 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) in a solution of 3,3'-diaminodiphenylsulfone and bis(2-methoxyethyl)ether, precipitating the reactant product in water, filtering and drying the recovered poly(amide-acid sulfone) and converting it to the poly(imidesulfone) by heating.

  19. Analysis techniques for the design of thermoplastic bumpers

    SciTech Connect

    Nimmer, R.P.; Bailey, O.A.; Paro, T.W.

    1987-01-01

    Increasingly, thermoplastic resins are being applied to automotive components which require structural performance. The work reported in this paper summarizes an ongoing effort to develop efficient mechanical technology for application in the design of thermoplastic bumpers. The technology development has included identification of material properties, investigation of basic component behavior, and finally the development of an automated system of analysis. A basic question often posed with regard to the analysis of structural components made of thermoplastics is whether the appropriate material properties are available and whether available analysis procedures can be applied accurately. This question was addressed through a program of fundamental material characterization, followed by structural component analysis. The analysis was then compared to test results from a parallel experimental program.

  20. Hyperviscous diblock copolymer vesicles

    NASA Astrophysics Data System (ADS)

    Dimova, R.; Seifert, U.; Pouligny, B.; Förster, S.; Döbereiner, H.-G.

    2002-03-01

    Giant vesicles prepared from the diblock copolymer polybutadien-b-polyethyleneoxide (PB-PEO) exhibit a shear surface viscosity, which is about 500 times higher than those found in common phospholipid bilayers. Our result constitutes the first direct measurement of the shear surface viscosity of such polymersomes. At the same time, we measure bending and stretching elastic constants, which fall in the range of values typical for lipid membranes. Pulling out a tether from an immobilized polymersome and following its relaxation back to the vesicle body provides an estimate of the viscous coupling between the two monolayers composing the polymer membrane. The detected intermonolayer friction is about an order of magnitude higher than the characteristic one for phospholipid membranes. Polymersomes are tough vesicles with a high lysis tension. This, together with their robust rheological properties, makes them interesting candidates for a number of technological applications.

  1. Star-like copolymer stabilized noble-metal nanoparticle powders

    NASA Astrophysics Data System (ADS)

    Cao, Peng-Fei; Yan, Yun-Hui; Mangadlao, Joey Dacula; Rong, Li-Han; Advincula, Rigoberto

    2016-03-01

    The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials.The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials. Electronic supplementary information (ESI) available: Synthesis scheme and the 1H NMR spectrum of PEI

  2. LARC-TPI: A multi-purpose thermoplastic polyimide

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    A linear thermoplastic polyimide, LARC-TPI, was characterized and developed for a variety of high temperature applications. In its fully imidized form, this material can be used as an adhesive for bonding metals such as titanium, aluminum, copper, brass, and stainless steel. LARC-TPI was evaluated as a thermoplastic for bonding large pieces of polyimide film to produce flexible, 100 void-free laminates for flexible circuit applications. The development of LARC-TPI as a potential molding powder, composite matrix resin, high temperature film and fiber is also discussed.

  3. Carbon fiber reinforced thermoplastic composites for future automotive applications

    NASA Astrophysics Data System (ADS)

    Friedrich, K.

    2016-05-01

    After a brief introduction to polymer composite properties and markets, the state of the art activities in the field of manufacturing of advanced composites for automotive applications are elucidated. These include (a) long fiber reinforced thermoplastics (LFT) for secondary automotive components, and (b) continuous carbon fiber reinforced thermosetting composites for car body applications. It is followed by future possibilities of carbon fiber reinforced thermoplastic composites for e.g. (i) crash elements, (ii) racing car seats, and (iii) production and recycling of automotive fenders.

  4. Adsorption depth profile of water on thermoplastic starch films

    SciTech Connect

    Bonno, B.; Laporte, J.L.; Paris, D.; D'Leon, R.T.

    2000-01-01

    It is well known that petroleum derived polymers are primary environmental contaminants. The study of new packing biodegradable materials has been the object of numerous papers in past years. Some of these new materials are the thermoplastic films derived from wheat starch. In the present paper, the authors study some of properties of wheat starch thermoplastic films, with various amounts of absorbed water, using photoacoustic spectroscopy techniques. The absorption depth profile of water in the starch substrate is determined for samples having a variable water level.

  5. Absorption depth profile of water on thermoplastic starch films

    SciTech Connect

    Bonno, B.; Laporte, J.L.; Paris, D.; D'Leon, R.T.

    2000-01-01

    It is well known that petroleum derived polymers are primary environmental contaminants. The study of new packing biodegradable materials has been the object of numerous papers in past years. Some of these new materials are the thermoplastic films derived from wheat starch. In the present paper, the authors study some of properties of wheat starch thermoplastic films, with various amounts of absorbed water, using photoacoustic spectroscopy techniques. The absorption depth profile of water in the starch substrate is determined for samples having a variable water level.

  6. Viscous and thermal modelling of thermoplastic composites forming process

    NASA Astrophysics Data System (ADS)

    Guzman, Eduardo; Liang, Biao; Hamila, Nahiene; Boisse, Philippe

    2016-10-01

    Thermoforming thermoplastic prepregs is a fast manufacturing process. It is suitable for automotive composite parts manufacturing. The simulation of thermoplastic prepreg forming is achieved by alternate thermal and mechanical analyses. The thermal properties are obtained from a mesoscopic analysis and a homogenization procedure. The forming simulation is based on a viscous-hyperelastic approach. The thermal simulations define the coefficients of the mechanical model that depend on the temperature. The forming simulations modify the boundary conditions and the internal geometry of the thermal analyses. The comparison of the simulation with an experimental thermoforming of a part representative of automotive applications shows the efficiency of the approach.

  7. Flexural fatigue of short fiber reinforced high temperature thermoplastics

    SciTech Connect

    Yau, S.; Chou, T.W.

    1985-04-01

    Short fiber reinforced thermoplastics are gaining increasing importance in the development of composite technology. In this investigation, the studies focus on three types of short glass fiber reinforced thermoplastics: (1) polyetherimide (PEI), (2) polyethersulphone (PES), and (3) polyetheretherketone (PEEK). These matrices possess good resistance to aviation fluids and ability to withstand high temperatures up to 600/sup 0/F. Specimens were evaluated at room temperature and at elevated temperatures under both static and dynamic loads. Fatigue tests reported herein were performed on Krouse sheet bending fatigue machines, operating at 1750 cpm and a constant deflection mode. Fatigue data are presented in traditional S-N plots. 3 references, 5 figures.

  8. Applications of azidosilane coupling agents in reinforced thermoplastic composites

    SciTech Connect

    Kolpak, F.J.

    1986-10-01

    Treatment of mica, glass microspheres, milled glass fibers and commercial chopped fiberglass with azidosilane coupling agents is shown to significantly improve the mechanical properties of these fillers/reinforcements in polyolefins relative to untreated controls. The unique chemistry of the azido groups allows for coupling with a wide variety of thermoplastic polymers. Surface characterization of native and modified fillers has proven to be a valuable adjunct to composite testing in optimizing the performance of acidosilanes coupling agents in filled or reinforced thermoplastics. 9 references, 9 figures, 3 tables.

  9. Pultrusion process development of a graphite reinforced polyetherimide thermoplastic composite

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Buckley, John D.; Dickerson, George E.; Johnson, Gary S.; Taylor, Edward C.; Covington, Edward W.

    1989-01-01

    High performance thermoplastic polymers do not contain reactants and solvents able to react with a pultrusion die to yield polymerization; consolidation is therefore performed with a rigid or a boardy prepreg, and consolidation must occur with polymers whose viscosities are of the order of 1 million centipoises or more. Die temperatures are typically above 400 C, by comparison with the 150-200 C encountered in thermosets. A methodical approach is presented here for the development of a pultrusion process suitable for polyetherimide and other engineering thermoplastics, employing SEM, DSC, TGA, and ultrasonic C-scanning.

  10. Failure behavior of a glass-fiber reinforced thermoplastic composite

    NASA Astrophysics Data System (ADS)

    Liang, Jiaai; Kalyanasundaram, Shankar

    2017-05-01

    In this work, experiments were conducted to stamp form glass-fiber reinforced thermoplastics with different widths of hour-glass shapes. A forming limit diagram (FLD) is established based on the experimental data for this material, depicting strain forming limits at different deformation modes. The material system involved in the study is a glass-fiber reinforced polypropylene composite (TWINTEX®) with a fiber orientation of 0°/90° along the warp and weft directions. In this study, the conventional FLD method is adapted to use on thermoplastic composites and it is found that the major principle strain limit is the highest when the strain ratio is around -0.5.

  11. Mechanical Properties of Isotactic Polypropylene Modified with Thermoplastic Potato Starch

    NASA Astrophysics Data System (ADS)

    Knitter, M.; Dobrzyńska-Mizera, M.

    2015-05-01

    In this paper selected mechanical properties of isotactic polypropylene (iPP) modified with potato starch have been presented. Thermoplastic starch (TPS) used as a modifier in the study was produced from potato starch modified with glycerol. Isotactic polypropylene/thermoplastic potato starch composites (iPP/TPS) that contained 10, 30, 50 wt.% of modified starch were examined using dynamic mechanical-thermal analysis, static tensile, Brinell hardness, and Charpy impact test. The studies indicated a distinct influence of a filler content on the mechanical properties of composites in comparison with non-modified polypropylene.

  12. Thermodynamics of coil-hyperbranched poly(styrene-b-acrylated epoxidized soybean oil) block copolymers

    NASA Astrophysics Data System (ADS)

    Lin, Fang-Yi; Hohmann, Austin; Hernández, Nacú; Cochran, Eric

    Here we present the phase behavior of a new type of coil-hyperbranched diblock copolymer: poly(styrene- b-acrylated epoxidized soybean oil), or PS-PAESO. PS-PAESO is an example of a biorenewable thermoplastic elastomer (bio-TPE). To date, we have shown that bio-TPEs can be economical commercial substitutes for their petrochemically derived analogues--such as poly(styrene- b-butadiene- b-styrene) (SBS)--in a range of applications including pressure sensitive adhesives and bitumen modification. From a polymer physics perspective, PS-PAESO is an interesting material in that it couples a linear coil-like block with a highly branched block. Thus in contrast to the past five decades of studies on linear AB diblock copolymers, coil-hyperbranched block copolymers are relatively unknown to the community and can be expected to deviate substantially from the standard ``universal'' phase behavior in the AB systems. To explore these new materials, we have constructed a library of PS-PAESO materials spanning a range of molecular weight and composition values. The phase transition behavior and the morphology information will be interpreted by isochronal temperature scanning in dynamic shear rheology, small angle X-ray scattering and the corresponding transmission electron microscopy.

  13. Laccase-mediated synthesis of lignin-core hyperbranched copolymers

    DOE PAGES

    Cannatelli, Mark D.; Ragauskas, Arthur J.

    2017-06-06

    Lignin, one of the major chemical constituents of woody biomass, is the second most abundant biopolymer found in nature. The pulp and paper industry has long produced lignin on the scale of millions of tons annually as a by-product of the pulping process, and the dawn of cellulosic ethanol production has further contributed to this amount. Historically, lignin has been perceived as a waste material and burned as a fuel for the pulping process. But, recent research has been geared toward developing cost-effective technologies to convert lignin into valuable commodities. Attributing to the polyphenolic structure of lignin, enzymatic modification ofmore » its surface using laccases (benzenediol:oxygen oxidoreductases, EC 1.10.3.2) has demonstrated to be highly successful. The current study aims at developing lignin-core hyperbranched copolymers via the laccase-assisted copolymerization of kraft lignin with methylhydroquinone and a trithiol. Based on the physical properties of the resulting material, it is likely that crosslinking reactions have taken place during the drying process to produce a copolymeric network rather than discrete hyperbranched copolymers, with NMR data providing evidence of covalent bonding between monomers. A preliminary thermal analysis data reveals that the copolymeric material possesses a moderate glass transition temperature and exhibits good thermostability, thus may have potential application as a lignin-based thermoplastic. Scanning electron microscopy images confirm the smooth, glossy surface of the material and that it is densely packed. Our results are a sustainable, ecofriendly, economic method to create an exciting novel biomaterial from a renewable feedstock while further enhancing lignin valorization.« less

  14. Laccase-mediated synthesis of lignin-core hyperbranched copolymers.

    PubMed

    Cannatelli, Mark D; Ragauskas, Arthur J

    2017-08-01

    Lignin, one of the major chemical constituents of woody biomass, is the second most abundant biopolymer found in nature. The pulp and paper industry has long produced lignin on the scale of millions of tons annually as a by-product of the pulping process, and the dawn of cellulosic ethanol production has further contributed to this amount. Historically, lignin has been perceived as a waste material and burned as a fuel for the pulping process. However, recent research has been geared toward developing cost-effective technologies to convert lignin into valuable commodities. Attributing to the polyphenolic structure of lignin, enzymatic modification of its surface using laccases (benzenediol:oxygen oxidoreductases, EC 1.10.3.2) has demonstrated to be highly successful. The current study aims at developing lignin-core hyperbranched copolymers via the laccase-assisted copolymerization of kraft lignin with methylhydroquinone and a trithiol. Based on the physical properties of the resulting material, it is likely that crosslinking reactions have taken place during the drying process to produce a copolymeric network rather than discrete hyperbranched copolymers, with NMR data providing evidence of covalent bonding between monomers. Preliminary thermal analysis data reveals that the copolymeric material possesses a moderate glass transition temperature and exhibits good thermostability, thus may have potential application as a lignin-based thermoplastic. Scanning electron microscopy images confirm the smooth, glossy surface of the material and that it is densely packed. The presented results are a sustainable, ecofriendly, economic method to create an exciting novel biomaterial from a renewable feedstock while further enhancing lignin valorization.

  15. Advanced thermoplastic materials for district heating piping systems

    SciTech Connect

    Raske, D.T.; Karvelas, D.E.

    1988-04-01

    The work described in this report represents research conducted in the first year of a three-year program to assess, characterize, and design thermoplastic piping for use in elevated-temperature district heating (DH) systems. The present report describes the results of a program to assess the potential usefulness of advanced thermoplastics as piping materials for use in DH systems. This includes the review of design rules for thermoplastic materials used as pipes, a survey of candidate materials and available mechanical properties data, and mechanical properties testing to obtain baseline data on a candidate thermoplastic material extruded as pipe. The candidate material studied in this phase of the research was a polyetherimide resin, Ultem 1000, which has a UL continuous service temperature rating of 338/degree/F (170/degree/C). The results of experiments to determine the mechanical properties between 68 and 350/degree/F (20 and 177/degree/C) were used to establish preliminary design values for this material. Because these prototypic pipes were extruded under less than optimal conditions, the mechanical properties obtained are inferior to those expected from typical production pipes. Nevertheless, the present material in the form of 2-in. SDR 11 pipe (2.375-in. O. D. by 0.216-in. wall) would have a saturated water design pressure rating of /approximately/34 psig at 280/degree/F. 16 refs., 6 figs., 8 tabs.

  16. Development and evaluation of thermoplastic street maintenance material

    NASA Technical Reports Server (NTRS)

    Siemens, W. D.

    1973-01-01

    An all-weather permanent street patching material was investigated for flexible and rigid pavements. The economic, operational, and material requirements are discussed along with the results of field tests with various mixtures of EVA resins and asphalt. Cost analyses for thermoplastic patching methods are included.

  17. Review of methods for fusion bonding thermoplastic composites

    SciTech Connect

    Benatar, A.; Gutowski, T.G.

    1987-02-01

    Bonding of thermoplastic composites is a critical step in the manufacture of aerospace structures. The objective of this project is to investigate different methods for fusion bonding thermoplastic composites quickly, with a good bond strength, and without warping and deconsolidation. This is best accomplished by heating and melting the thermoplastic on the bond surface only, and then pressing the parts together for a fusion bond. For this purpose, a variety of surface heating techniques were examined for bonding of PEEK and J Polymer composites. These included: resistance heating, infrared heating, induction heating, dielectric/microwave heating, and ultrasonic welding. In resistance heating, a single prepreg ply was placed between the composites and heated by passing electric current through the graphite fibers. With induction heating, a single ply of nickel coated graphite fibers was placed between the composites and heated. Ultrasonic welding was done by molding thermoplastic-only energy directors into the composites; the ultrasonic vibration melted these energy directors thereby fusion bonding the parts. 20 references.

  18. Antimicrobial thermoplastic materials for biomedical applications prepared by melt processing

    NASA Astrophysics Data System (ADS)

    Botta, L.; Scaffaro, R.; Ceraulo, M.; Gallo, G.

    2014-05-01

    In this work thermoplastic polymers with antimicrobial properties were prepared by incorporating an antibiotic, i.e., ciprofloxacin (CFX), by melt processing. Two different polymers were used as matrices, i.e., polypropylene (PP) and poly(lactid acid) (PLA) and different concentrations of CFX have been incorporated. The antimicrobial properties, the release kinetic and the mechanical performances of the prepared materials were evaluated.

  19. Hybridized Thermoplastic Aramids: Enabling Material Technology For Future Force Headgear

    DTIC Science & Technology

    2006-11-01

    weight polyethylene (UHMWPE) fibers with thermoplastic elastomer matrices. The properties and use of these materials have been well described... elastomer Glass stitch bond Epoxy UHMWPE reported as a pass/fail based on the threshold criteria defined in performance specifications... elastomer Glass stitch bond Epoxy UHMWPE CANDIDATE MATERIALS FOR IMPROVED BALLISTIC EFFICIENCY DETAILS OF POLYOLEFIN-BASED ARAMID microscopy SEM Stage I

  20. Elastic/viscoplastic constitutive model for fiber reinforced thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Gates, T. S.; Sun, C. T.

    1991-01-01

    A constitutive model to describe the elastic/viscoplastic behavior of fiber-reinforced thermoplastic composites under plane stress conditions is presented. Formulations are given for quasi-static plasticity and time-dependent viscoplasticity. Experimental procedures required to generate the necessary material constants are explained, and the experimental data is compared to the predicted behavior.

  1. Method for preparing spherical thermoplastic particles of uniform size

    DOEpatents

    Day, J.R.

    1975-11-17

    Spherical particles of thermoplastic material of virtually uniform roundness and diameter are prepared by cutting monofilaments of a selected diameter into rod-like segments of a selected uniform length which are then heated in a viscous liquid to effect the formation of the spherical particles.

  2. The compression of wood/thermoplastic fiber mats during consolidation

    Treesearch

    Karl R. Englund; Michael P. Wolcott; John C. Hermanson

    2004-01-01

    Secondary processing of non-woven wood and wood/thermoplastic fiber mats is generally performed using compression molding, where heated platens or dies form the final product. Although the study and use of wood-fiber composites is widespread, few research efforts have explicitly described the fundamentals of mat consolidation. In contrast, the wood composite literature...

  3. Processing and characterization of unidirectional thermoplastic nanocomposites

    NASA Astrophysics Data System (ADS)

    Narasimhan, Kameshwaran

    The manufacture of continuous fibre-reinforced thermoplastic nanocomposites is discussed for the case of E-Glass reinforced polypropylene (PP) matrix and for E-Glass reinforced Polyamide-6 (Nylon-6), with and without dispersed nanoclay (montmorillonite) platelets. The E-Glass/PP nanocomposite was manufactured using pultrusion, whereas the E-Glass/Nylon-6 nanocomposite was manufactured using compression molding. Mechanical characterization of nanocomposites were performed and compared with traditional microcomposites. Compressive as well as shear strength of nanocomposites was improved by improving the yield strength of the surrounding matrix through the dispersion of nanoclay. Significant improvements were achieved in compressive strength and shear strength with relatively low nanoclay loadings. Initially, polypropylene with and without nanoclay were melt intercalated using a single-screw extruder and the pultruded nanocomposite was fabricated using extruded pre-impregnated (pre-preg) tapes. Compression tests were performed as mandated by ASTM guidelines. SEM and TEM characterization revealed presence of nanoclay in an intercalated and partially exfoliated morphology. Mechanical tests confirmed significant improvements in compressive strength (˜122% at 10% nanoclay loading) and shear strength (˜60% at 3% nanoclay loading) in modified pultruded E-Glass/PP nanocomposites in comparison with baseline properties. Uniaxial tensile tests showed a small increase in tensile strength (˜3.4%) with 3% nanoclay loading. Subsequently, E-Glass/Nylon-6 nanocomposite panels were manufactured by compression molding. Compression tests were performed according to IITRI guidelines, whereas short beam shear and uni-axial tensile tests were performed according to ASTM standards. Mechanical tests confirmed strength enhancement with nanoclay addition, with a significant improvement in compressive strength (50% at 4% nanoclay loading) and shear strength (˜36% at 4% nanoclay loading

  4. On-line consolidation of thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Shih, Po-Jen

    An on-line consolidation system, which includes a computer-controlled filament winding machine and a consolidation head assembly, has been designed and constructed to fabricate composite parts from thermoplastic towpregs. A statistical approach was used to determine the significant processing parameters and their effect on the mechanical and physical properties of composite cylinders fabricated by on-line consolidation. A central composite experimental design was used to select the processing conditions for manufacturing the composite cylinders. The thickness, density, void content, degree of crystallinity and interlaminar shear strength (ILSS) were measured for each composite cylinder. Micrographs showed that complete intimate contact and uniform fiber-matrix distribution were achieved. The degree of crystallinity of the cylinders was found to be in the range of 25-30%. Under optimum processing conditions, an ILSS of 58 MPa and a void content of <1% were achieved for APC-2 (PEEK/Carbon fiber) composite cylinders. An in-situ measurement system which uses a slip ring assembly and a computer data acquisition system was developed to obtain temperature data during winding. Composite cylinders were manufactured with eight K-type thermocouples installed in various locations inside the cylinder. The temperature distribution inside the composite cylinder during winding was measured for different processing conditions. ABAQUS finite element models of the different processes that occur during on-line consolidation were constructed. The first model was used to determine the convective heat transfer coefficient for the hot-air heat source. A convective heat transfer coefficient of 260 w/msp{2°}K was obtained by matching the calculated temperature history to the in-situ measurement data. To predict temperature distribution during winding an ABAQUS winding simulation model was developed. The winding speed was modeled by incrementally moving the convective boundary conditions

  5. ABC triblock surface active block copolymer with grafted ethoxylated fluoroalkyl amphiphilic side chains for marine antifouling/fouling-release applications.

    PubMed

    Weinman, Craig J; Finlay, John A; Park, Daewon; Paik, Marvin Y; Krishnan, Sitaraman; Sundaram, Harihara S; Dimitriou, Michael; Sohn, Karen E; Callow, Maureen E; Callow, James A; Handlin, Dale L; Willis, Carl L; Kramer, Edward J; Ober, Christopher K

    2009-10-20

    An amphiphilic triblock surface-active block copolymer (SABC) possessing ethoxylated fluoroalkyl side chains was synthesized through the chemical modification of a polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene polymer precursor. Bilayer coatings on glass slides consisting of a thin layer of the amphiphilic SABC spray coated on a thick layer of a polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) thermoplastic elastomer were prepared for biofouling assays with the green alga Ulva and the diatom Navicula. Dynamic water contact angle analysis and X-ray photoelectron spectroscopy (XPS) were used to characterize the surfaces. Additionally, the effect of the Young's modulus of the coating on the release properties of sporelings (young plants) of the green alga Ulva was examined through the use of two different SEBS thermoplastic elastomers possessing modulus values of an order of magnitude in difference. The amphiphilic SABC was found to reduce the settlement density of zoospores of Ulva as well as the strength of attachment of sporelings. The attachment strength of the sporelings was further reduced for the amphiphilic SABC on the "low"-modulus SEBS base layer. The weaker adhesion of diatoms, relative to a PDMS standard, further highlights the antifouling potential of this amphiphilic triblock hybrid copolymer.

  6. Copolymers For Capillary Gel Electrophoresis

    DOEpatents

    Liu, Changsheng; Li, Qingbo

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  7. An asymmetric A-B-A' metallo-supramolecular triblock copolymer linked by Ni(2+)-bis-terpyridine complexes at one junction.

    PubMed

    Li, Haixia; Wei, Wei; Xiong, Huiming

    2016-02-07

    A metallo-supramolecular triblock copolymer polystyrene-b-polyisoprene-[Ni(2+)]-polystyrene (SI-[Ni(2+)]-S') has been efficiently prepared using a one-pot, two-step procedure, where the blocks are held by bis-terpyridine complexes at the junction of SI-S'. This specific metallo-supramolecular chemistry is demonstrated to be a robust approach to potentially broaden the diversity of block copolymers. The location of the metal-ligand complexes has a profound influence on the phase separation of the triblock copolymer in the bulk, which results in a distinctive phase segregation between the end blocks and leads to an unexpected asymmetry of the triblock copolymer. The metal-ligand complexes are found to be preferentially located on the adjacent spherical domain and form a core-shell structure. The resulting multiphase material exhibits distinct elastomeric properties with significant toughness and creep recovery behavior. This type of triblock copolymer is anticipated to be a novel class of hybrid thermo-plastic elastomeric material with wide tunability and functionality.

  8. Individual chromosomes as viscoelastic copolymers

    NASA Astrophysics Data System (ADS)

    Almagro, S.; Dimitrov, S.; Hirano, T.; Vallade, M.; Riveline, D.

    2003-09-01

    We report elastic measurements of individual chromosomes observed in vitro. Free fluctuations of shapes show that a chromosome can be seen as a copolymer, exhibiting rigid regions alternating with semi-flexible regions. We characterize this behavior and compare it with known biopolymers. We further show that the inner part of a chromosome exhibits viscoelasticity, as extracted by the loading rate dependence of the stretch modulus. Taken together, these data suggest an organization for the chromosome as a copolymer composed of an inner rigid core exhibiting viscoelasticity surrounded by an elastic soft envelope.

  9. Ultrashort pulse laser micro-welding of cyclo-olefin copolymers

    NASA Astrophysics Data System (ADS)

    Roth, Gian-Luca; Rung, Stefan; Hellmann, Ralf

    2017-06-01

    We report on the joining of transparent thermoplastic polymers using infrared femtosecond laser pulses. Due to nonlinear absorption, the developed micro-welding process for cyclo-olefin copolymers does not require any intermediate absorbing layers or any surface pre-processing of the welding partners. In view of an optimized and stable micro-welding process, the influence of the welding speed and focal position on both, the quality and shear force strength are investigated. We highlight that welding seam widths of down to 65 μm are feasible for welding speeds of up to 75 mm/s. However, a variation of the welding speed affects the required focal position for a successful joining process. The shear force strength of the welding seam is determined to 37 MPa, which corresponds to 64% of the shear strength of the bulk material and is not affected by the welding speed.

  10. Polyhydroxyalkanoate-based natural synthetic hybrid copolymer films: A small-angle neutron scattering study

    NASA Astrophysics Data System (ADS)

    Foster, L. John R.; Knott, Robert; Sanguanchaipaiwong, Vorapat; Holden, Peter J.

    2006-11-01

    Polyhydroxyalkanoates have attracted attention as biodegradable alternatives to conventional thermoplastics and as biomaterials. Through modification of their biosynthesis using Pseudomonas oleovorans, we have manipulated the material properties of these biopolyesters and produced a natural-synthetic hybrid copolymer of polyhydroxyoctanoate- block-diethylene glycol (PHO- b-DEG). A mixture of PHO and PHO-DEG were solvent cast from analytical grade chloroform and analysed using small-angle neutron scattering. A scattering pattern, easily distinguished above the background, was displayed by the films with a diffraction ring at q∼0.12 Å -1. This narrow ring of intensity is suggestive of a highly ordered system. Analysis of the diffraction pattern supported this concept and showed a d-spacing of approximately 50 Å. In addition, conformation of the hybrid polymer chains can be manipulated to support their self-assembly into ordered microporous films.

  11. Gradient copolymers - a new class of materials

    SciTech Connect

    Greszta, D.; Matyjaszewski, K.

    1996-10-01

    In this work preparation of a new class of copolymers, namely gradient copolymers via controlled Atom Transfer Radical Polymerization (ATRP) is described. Due to the compositional gradient along the chain, gradient copolymers are expected to exhibit unique physical characteristics as compared to block and random copolymers with similar composition and molecular weight. These include unusual phase separation behavior, and mechanical and thermal properties. Using ATRP one can prepare gradient copolymers via two routes. The first one is the one-pot copolymerization of monomers with different reactitvity ratios r{sub 1}{much_gt}r{sub 2}. The second one is a copolymerization while continuously changing the comonomers feed composition.

  12. Crystalline imide/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor); Bass, Robert G. (Inventor)

    1995-01-01

    Crystalline imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly)arylene ethers) in polar aprotic solvents and chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The block copolymers of the invention have one glass transition temperature or two, depending on the particular structure and/or the compatibility of the block units. Most of these crystalline block copolymers for tough, solvent resistant films with high tensile properties. While all of the copolymers produced by the present invention are crystalline, testing reveals that copolymers with longer imide blocks or higher imide content have increased crystallinity.

  13. Thermoplastic Elastomers as LOVA (Low Vulnerability Ammunition) Binders.

    DTIC Science & Technology

    1983-12-01

    copolymers is being studied. This series is prepared by capping PPO using the diisocyanate NDI and chain extension using 4,4’-diamino-diphenylether and...series consists of the reaction of polypropylene oxide (PPO) with 1.4 diphenyl methane diisocyanate (MDI) as capping agent to form a capped diol. This...diphenyl methane diisocyanate (MDI). The capped diol reacts with pyromellitic dianhydride to form a segmented polyether-polyimide copolymer. A detailed

  14. Interfacial strength development in thermoplastic resins and fiber-reinforced thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Howes, Jeremy C.; Loos, Alfred C.

    1987-01-01

    An experimental program to develop test methods to be used to characterize interfacial (autohesive) strength development in polysulfone thermoplastic resin and graphite-polysulfone prepreg during processing is reported. Two test methods were used to examine interfacial strength development in neat resin samples. These included an interfacial tension test and a compact tension (CT) fracture toughness test. The interfacial tensile test proved to be very difficult to perform with a considerable amount of data scatter. Thus, the interfacial test was discarded in favor of the fracture toughness test. Interfacial strength development was observed by measuring the refracture toughness of precracked compact tension specimens that were rehealed at a given temperature and contact time. The measured refracture toughness was correlated with temperature and contact time. Interfacial strength development in graphite-polysulfone unidirectional composites was measured using a double cantilever beam (DCB) interlaminar fracture toughness test. The critical strain energy release rate of refractured composite specimens was measured as a function of healing temperature and contact time.

  15. Study of correlations between microstructure and conductivity in a thermoplastic polyurethane electrolyte

    SciTech Connect

    Furtado, C.A.

    1999-08-26

    Micro-Raman and positron annihilation lifetime spectroscopy (PALS) have been used to investigate the structure of a thermoplastic polyurethane/LiClO{sub 4} solid flexible polymer electrolyte at room temperature. Correlation between the free volume and carrier concentration with ionic conductivity was observed. The polyurethane soft phase consisted of a poly(tetramethylene glycol-co-ethylene glycol) copolymer reinforced by condensation with hexamethyldiisocianate. The range of salt concentration between 5 and 35 wt %, which attained the beginning of phase segregation, was also studied by differential scanning calorimetry (DSC), which showed the presence of three thermal events; the soft-phase T{sub g}, a change in heat capacity suggested as the hard-phase T{sub g}, and a hard-phase ordering endotherm. The total ionic conductivity was found to be approximately 4 {times} 10{sup {minus}6} S cm{sup {minus}1} at 23 C up to 27 wt % salt, whereas there were pronounced changes observed by the spectroscopic techniques. The PALS measurements indicated a decrease of 40% of the ratio (V{sub f}I{sub 3}/(V{sub f}I{sub 3}){sub 0}) between the free volume parameters probed by the positron particle. This ratio is proportional to the fractional free volume of the system. The micro-Raman results showed an increase of ionic aggregation, although the charge carrier concentration increased significantly in the range of compositions studied. The opposite effects of the microstructural changes and the maximum conductivity value, in the observed range of concentrations, are discussed.

  16. Processing and Damage Tolerance of Continuous Carbon Fiber Composites Containing Puncture Self-Healing Thermoplastic Matrix

    NASA Technical Reports Server (NTRS)

    Grimsley, Brian W.; Gordon, Keith L.; Czabaj, Michael W.; Cano, Roberto J.; Siochi, Emilie J.

    2012-01-01

    Research at NASA Langley Research Center (NASA LaRC) has identified several commercially available thermoplastic polymers that self-heal after ballistic impact and through-penetration. One of these resins, polybutadiene graft copolymer (PB(sub g)), was processed with unsized IM7 carbon fibers to fabricate reinforced composite material for further evaluation. Temperature dependent characteristics, such as the degradation point, glass transition (T(sub g)), and viscosity of the PBg polymer were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic parallel plate rheology. The PBg resin was processed into approximately equal to 22.0 cm wide unidirectional prepreg tape in the NASA LaRC Advanced Composites Processing Research Laboratory. Data from polymer thermal characterization guided the determination of a processing cycle used to fabricate quasi-isotropic 32-ply laminate panels in various dimensions up to 30.5cm x 30.5cm in a vacuum press. The consolidation quality of these panels was analyzed by optical microscopy and acid digestion. The process cycle was further optimized based on these results and quasi-isotropic, [45/0/-45/90]4S, 15.24cm x 15.24cm laminate panels were fabricated for mechanical property characterization. The compression strength after impact (CAI) of the IM7/pBG composites was measured both before and after an elevated temperature and pressure healing cycle. The results of the processing development effort of this composite material as well as the results of the mechanical property characterization are presented in this paper.

  17. Influence of carbon nanotubes on the properties of epoxy based composites reinforced with a semicrystalline thermoplastic

    NASA Astrophysics Data System (ADS)

    Díez-Pascual, A.; Shuttleworth, P.; Gónzalez-Castillo, E.; Marco, C.; Gómez-Fatou, M.; Ellis, G.

    2014-08-01

    Novel ternary nanocomposites based on a thermoset (TS) system composed of triglycidyl p-aminophenol (TGAP) epoxy resin and 4,4'-diaminodiphenylsulfone (DDS) curing agent incorporating 5 wt% of a semicrystalline thermoplastic (TP), an ethylene/1-octene copolymer, and 0.5 or 1.0 wt% multi-walled carbon nanotubes (MWCNTs) have been prepared via physical blending and curing. The influence of the TP and the MWCNTs on the curing process, morphology, thermal and mechanical properties of the hybrid nanocomposites has been analyzed. Different morphologies evolved depending on the CNT content: the material with 0.5 wt% MWCNTs showed a matrix-dispersed droplet-like morphology with well-dispersed nanofiller that selectively located at the TS/TP interphase, while that with 1.0 wt% MWCNTs exhibited coarse dendritic TP areas containing agglomerated MWCNTs. Although the cure reaction was accelerated in its early stage by the nanofillers, curing occurred at a lower rate since these obstructed chain crosslinking. The nanocomposite with lower nanotube content displayed two crystallization peaks at lower temperature than that of pure TP, while a single peak appearing at similar temperature to that of TP was observed for the blend with higher nanotube loading. The highest thermal stability was found for TS/TP (5.0 wt%)/MWCNTs (0.5 wt%), due to a synergistic barrier effect of both TP and the nanofiller. Moreover, this nanocomposite displayed the best mechanical properties, with an optimal combination of stiffness, strength and toughness. However, poorer performance was found for TS/TP (5.0 wt%)/MWCNTs (1.0 wt%) due to the less effective reinforcement of the agglomerated nanotubes and the coalescence of the TP particles into large areas. Therefore, finely tuned morphologies and properties can be obtained by adjusting the nanotube content in the TS/TP blends, leading to high-performance hybrid nanocomposites suitable for structural and high-temperature applications.

  18. The relative fire resistance of select thermoplastic materials. [for aircraft interiors

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Parker, J. A.

    1978-01-01

    The relative thermal stability, flammability, and related thermochemical properties of some thermoplastic materials currently used in aircraft interiors as well as of some candidate thermoplastics were investigated. Currently used materials that were evaluated include acrylonitrile butadiene styrene, bisphenol A polycarbonate, polyphenylene oxide, and polyvinyl fluoride. Candidate thermoplastic materials evaluated include: 9,9-bis(4-hydroxyphenyl)fluorene polycarbonate-poly(dimethylsiloxane) block polymer, chlorinated polyvinylchloride homopolymer, phenolphthalein polycarbonate, polyethersulfone, polyphenylene sulfide, polyarylsulfone, and polyvinylidene fluoride.

  19. The relative fire resistance of select thermoplastic materials. [for aircraft interiors

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Parker, J. A.

    1978-01-01

    The relative thermal stability, flammability, and related thermochemical properties of some thermoplastic materials currently used in aircraft interiors as well as of some candidate thermoplastics were investigated. Currently used materials that were evaluated include acrylonitrile butadiene styrene, bisphenol A polycarbonate, polyphenylene oxide, and polyvinyl fluoride. Candidate thermoplastic materials evaluated include: 9,9-bis(4-hydroxyphenyl)fluorene polycarbonate-poly(dimethylsiloxane) block polymer, chlorinated polyvinylchloride homopolymer, phenolphthalein polycarbonate, polyethersulfone, polyphenylene sulfide, polyarylsulfone, and polyvinylidene fluoride.

  20. 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

  1. Liquid ethylene-propylene copolymers

    NASA Technical Reports Server (NTRS)

    Rhein, R. A.; Ingham, J. D.; Humphrey, M. F.

    1975-01-01

    Oligomers are prepared by heating solid ethylene-propylene rubber in container that retains solid and permits liquid product to flow out as it is formed. Molecular weight and viscosity of liquids can be predetermined by process temperature. Copolymers have low viscosity for given molecular weight.

  2. Polyether-polyester graft copolymer

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor)

    1987-01-01

    Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

  3. Electrochemical Deposition Of Conductive Copolymers

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, Ganesan; Distefano, Salvador; Liang, Ranty H.

    1991-01-01

    Experiments show electrically conductive films are deposited on glassy carbon or indium tin oxide substrates by electrochemical polymerization of N-{(3-trimethoxy silyl) propyl} pyrrole or copolymerization with pyrrole. Copolymers of monomer I and pyrrole exhibit desired electrical conductivity as well as desired adhesion and other mechanical properties. When fully developed, new copolymerization process useful in making surface films of selectable conductivity.

  4. Process for Preparing a Tough, Soluble, Aromatic, Thermoplastic Copolyimide

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    1997-01-01

    A process for preparing a tough, soluble, aromatic, thermoplastic copolyimide is provided. The process comprises the steps of (a) providing 4.4'-oxydiphthalic anhydride to 3,4,3',4'-biphenyltetracarboxylic dianhydride at a mole ratio ranging from about 25 mole percent to 75 mole percent to 75 mole percent to about 25 mole percent; (b) adding 3,4'-oxydianiline to form a mixture; (c) adding a polar aprotic or polar protic solvent to the mixture to form a solution having a percentage of solids capable of maintaining polymer solubility; (d) stirring the solution to allow it to react; (e) adding an azeotropic solvent to the solution and heating to remove water; (f) cooling the solution of step (e) to room temperature and recovering the tough, soluble, aromatic, thermoplastic copolyimide.

  5. Toroid Joining Gun. [thermoplastic welding system using induction heating

    NASA Technical Reports Server (NTRS)

    Buckley, J. D.; Fox, R. L.; Swaim, R J.

    1985-01-01

    The Toroid Joining Gun is a low cost, self-contained, portable low powered (100-400 watts) thermoplastic welding system developed at Langley Research Center for joining plastic and composite parts using an induction heating technique. The device developed for use in the fabrication of large space sructures (LSST Program) can be used in any atmosphere or in a vacuum. Components can be joined in situ, whether on earth or on a space platform. The expanded application of this welding gun is in the joining of thermoplastic composites, thermosetting composites, metals, and combinations of these materials. Its low-power requirements, light weight, rapid response, low cost, portability, and effective joining make it a candidate for solving many varied and unique bonding tasks.

  6. Pultrusion with thermoplastics for the fabrication of structures in space

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Macconochie, Ian O.; Johnson, Gary S.

    1988-01-01

    The use of the pultrusion method to produce structures in space is proposed. This technique is based on transporting materials in coils or bundles and fabricating the structures in space. Two methods for thermoplastic impregnation of advanced composite are described. The properties of three pultruded thermoplastic matrix materials, polyphenylene sulfide, polyetherimide (PEI), and polyetheretherketone (PEEK) are discussed and evaluated. It is observed that the pultrusions containing PEI and PEEK reveal post-fabrication potential of lightweight, high strength advanced composites and this method of fabrication produces strength values comparable to those of conventional techniques. Earth-based and space-based planetary shelter models are developed and compared. It is noted that cargo storage volume is dependent on a combination of profiles, packaging, and manufacturing methods.

  7. Micro hot embossing of thermoplastic polymers: a review

    NASA Astrophysics Data System (ADS)

    Peng, Linfa; Deng, Yujun; Yi, Peiyun; Lai, Xinmin

    2014-01-01

    Micro hot embossing of thermoplastic polymers is a promising process to fabricate high precision and high quality features in micro/nano scale. This technology has experienced more than 40 years development and has been partially applied in industrial production. Three modes of micro hot embossing including plate-to-plate, roll-to-plate and roll-to-roll have been successively developed to meet the increasing demand for large-area patterned polymeric films. This review surveys recent progress of micro hot embossing in terms of polymeric material behavior, embossing process and corresponding apparatus. Besides, challenges and innovations in mold fabrication techniques are comprehensively summarized and industrial applications are systematically cataloged as well. Finally, technical challenges and future trends are presented for micro hot embossing of thermoplastic polymers.

  8. Thermoplastic starch-waxy maize starch nanocrystals nanocomposites.

    PubMed

    Angellier, Hélène; Molina-Boisseau, Sonia; Dole, Patrice; Dufresne, Alain

    2006-02-01

    Waxy maize starch nanocrystals obtained by hydrolysis of native granules were used as a reinforcing agent in a thermoplastic waxy maize starch matrix plasticized with glycerol. Compared to our previous studies on starch nanocrystals reinforced natural rubber (NR) [Macromolecules 2005, 38, 3783; 2005, 38, 9161], the present system presents two particularities: (i) thermoplastic starch is a polar matrix, contrarily to NR, and (ii) the chemical structures of the matrix and the filler are similar. The influence of the glycerol content, filler content, and aging on the reinforcing properties of waxy maize starch nanocrystals (tensile tests, DMA) and crystalline structure (X-ray diffraction) of materials were studied. It was shown that the reinforcing effect of starch nanocrystals can be attributed to strong filler/filler and filler/matrix interactions due to the establishment of hydrogen bonding. The presence of starch nanocrystals leads to a slowing down of the recrystallization of the matrix during aging in humid atmosphere.

  9. Toroid Joining Gun. [thermoplastic welding system using induction heating

    NASA Technical Reports Server (NTRS)

    Buckley, J. D.; Fox, R. L.; Swaim, R J.

    1985-01-01

    The Toroid Joining Gun is a low cost, self-contained, portable low powered (100-400 watts) thermoplastic welding system developed at Langley Research Center for joining plastic and composite parts using an induction heating technique. The device developed for use in the fabrication of large space sructures (LSST Program) can be used in any atmosphere or in a vacuum. Components can be joined in situ, whether on earth or on a space platform. The expanded application of this welding gun is in the joining of thermoplastic composites, thermosetting composites, metals, and combinations of these materials. Its low-power requirements, light weight, rapid response, low cost, portability, and effective joining make it a candidate for solving many varied and unique bonding tasks.

  10. Screw-actuated displacement micropumps for thermoplastic microfluidics.

    PubMed

    Han, J Y; Rahmanian, O D; Kendall, E L; Fleming, N; DeVoe, D L

    2016-10-05

    The fabrication of on-chip displacement pumps integrated into thermoplastic chips is explored as a simple and low cost method for achieving precise and programmable flow control for disposable microfluidic systems. The displacement pumps consist of stainless steel screws inserted into threaded ports machined into a thermoplastic substrate which also serve as on-chip reagent storage reservoirs. Three different methods for pump sealing are investigated to enable high pressure flows without leakage, and software-defined control of multiple pumps is demonstrated in a self-contained platform using a compact and self-contained microcontroller for operation. Using this system, flow rates ranging from 0.5-40 μl min(-1) are demonstrated. The pumps are combined with on-chip burst valves to fully seal multiple reagents into fabricated chips while providing on-demand fluid distribution in a downstream microfluidic network, and demonstrated for the generation of size-tunable water-in-oil emulsions.

  11. Development and Characterization of Amorphous Thermoplastic Matrix Graphene Nanocomposites

    PubMed Central

    Greco, Antonio; Timo, Alessia; Maffezzoli, Alfonso

    2012-01-01

    The aim of the present work is the development of amorphous thermoplastic matrix nanocomposites based on graphite nanoparticles. Different types of graphite were used, including unmodified graphite, graphene nanoplatelets and graphite intercalation compounds. Graphite intercalation compounds were subjected to thermal treatment to attain exfoliation of the nanofiller. The exfoliation process was studied by means of thermal analysis. The nanofillers and nanocomposites were characterized by means of X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analysis. The nanocomposites were further characterized by means of mechanical and dielectric analysis. The flammability of the nanocomposites was also analyzed. Results obtained indicate that addition of the nanofiller allows improving the proprieties of the amorphous thermoplastic matrix. The effect of the degree of dispersion of the nanofiller is particularly relevant for the dielectric properties of the nanocomposites, whereas no direct correlation between degree of dispersion and mechanical properties can be observed.

  12. Method for shaping sheet thermoplastic and the like

    NASA Technical Reports Server (NTRS)

    Akilian, Mireille K. (Inventor); Schattenburg, Mark L. (Inventor)

    2011-01-01

    Processes and apparati for shaping sheet glass or thermoplastic materials use force from a layer of a flowing fluid, such as air, between the sheet and a mandrel at close to the softening temperature of the thermoplastic. The shape is preserved by cooling. The shape of the air bearing mandrel and the pressure distribution of the fluid contribute to the final shape. A process can be conducted on one or two surfaces such that the force from the air layer is on one or two surfaces of the sheet. The gap size between the sheet and mandrel determines the pressure profile in the gap, which also determines the final sheet shape. In general, smaller gaps lead to larger viscous forces. The pressure profile depends on the shape of the mandrel, the size of the fluid gap and the sheet and the fluid supply pressure.

  13. Numerical Modeling for Combustion of Thermoplastic Materials in Microgravity

    NASA Technical Reports Server (NTRS)

    Butler, Kathryn M.

    1997-01-01

    A time-dependent, three-dimensional model is under development to predict the temperature field, burning rate, and bubble bursting characteristics of burning thermoplastic materials in microgravity. Model results will be compared with experiments performed under microgravity and normal gravity conditions. The model will then be used to study the effects of variations in material properties and combustion conditions on burning rate and combustion behavior.

  14. TOPICAL REVIEW: Review on micro molding of thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Heckele, M.; Schomburg, W. K.

    2004-03-01

    Molding of micro components from thermoplastic polymers has become a routinely used industrial production process. This paper describes both the more than 30-year-old history and the present state of development and applications. Hot embossing, injection molding, reaction injection molding, injection compression molding, thermoforming, and various types of tool fabrication are introduced and their advantages and drawbacks are discussed. In addition, design considerations, process limitations, and commercially available micro molding machines are presented.

  15. Method to determine factors contributing to thermoplastic sheet shrinkage

    NASA Astrophysics Data System (ADS)

    Rensch, Greg J.; Frye, Brad A.

    A test method is presented for the determination of shrinkage behavior in vacuum-formed thermoplastic resin sheeting, as presently simulated for various resin lots, sheet-gage thicknesses, sheet orientations, and mold profiles. The thermoforming machine and vacuum-forming mold characteristics are discussed. It is established that the four variable factors exert statistically significant effects on the shrinkage response of three Declar resin lots, but that these are of no real practical significance for either engineering or manufacturing operations.

  16. Structural response of bead-stiffened thermoplastic shear webs

    NASA Technical Reports Server (NTRS)

    Rouse, Marshall

    1991-01-01

    The results of an experimental and analytical study of the structural response and failure characteristics of selected bead-stiffened thermoplastic shear-webs are presented. Results are given for specimens with one stiffeneer, with two stiffeners, and different stiffener geometries. Selected analytical results that were obtained with the Computational Structural Mechanics (CSM) Testbed computer code are presented. Analytical results that describe normal and transverse shear stress are also presented.

  17. Laminated thermoplastic composite material from recycled high density polyethylene

    NASA Technical Reports Server (NTRS)

    Liu, Ping; Waskom, Tommy L.

    1994-01-01

    The design of a materials-science, educational experiment is presented. The student should understand the fundamentals of polymer processing and mechanical property testing of materials. The ability to use American Society for Testing and Materials (ASTM) standards is also necessary for designing material test specimens and testing procedures. The objectives of the experiment are (1) to understand the concept of laminated composite materials, processing, testing, and quality assurance of thermoplastic composites and (2) to observe an application example of recycled plastics.

  18. Modified Single-Wall Carbon Nanotubes for Reinforce Thermoplastic Polyimide

    NASA Technical Reports Server (NTRS)

    Lebron-COlon, Marisabel; Meador, Michael A.

    2006-01-01

    A significant improvement in the mechanical properties of the thermoplastic polyimide film was obtained by the addition of noncovalently functionalized single-wall carbon nanotubes (SWNTs). Polyimide films were reinforced using pristine SWNTs and functionalized SWNTs (F-SWNTs). The tensile strengths of the polyimide films containing F-SWNTs were found to be approximately 1.4 times higher than those prepared from pristine SWNTs.

  19. Potential for Advanced Thermoplastic Composites in Space Systems

    DTIC Science & Technology

    1990-11-01

    Rapid cycle times, reprocessiblity, and thermoformability have led to projections of 30 to 90% costs savings for six aeronautical components—F/A 18 LEX...processes such as diaphragm forming, stamping, fully consolidated tape placement, welding, pultrusion, thermoform shaping, and thermoplastic joining...INTERCEPTOR STRUCTURE SKIN MODULE • Optical • Kinetic • Platform • Packaging Size Configuration Production Rate Special Features • Very large

  20. Elastic/viscoplastic behavior of fiber-reinforced thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Wang, C.; Sun, C. T.; Gates, T. S.

    1990-01-01

    An elastic/viscoplastic constitutive model was used to characterize the nonlinear and rate dependent behavior of a continuous fiber-reinforced thermoplastic composite. This model was incorporated into a finite element program for the analysis of laminated plates and shells. Details on the finite element formulation with the proposed constitutive model were presented. The numerical results were compared with experimental data for uniaxial tension and three-point bending tests of (+ or - 45 deg)3s APC-2 laminates.

  1. Ultrasonic assisted consolidation of commingled thermoplastic/glass fibers rovings

    NASA Astrophysics Data System (ADS)

    Lionetto, Francesca; Dell'Anna, Riccardo; Montagna, Francesco; Maffezzoli, Alfonso

    2015-04-01

    Thermoplastic matrix composites are finding new applications in different industrial area thanks to their intrinsic advantages related to environmental compatibility and processability. The approach presented in this work consists in the development of a technology for the simultaneous deposition and consolidation of commingled thermoplastic rovings through to the application of high energy ultrasound. An experimental equipment, integrating both fiber impregnation and ply consolidation in a single process, has been designed and tested. It is made of an ultrasonic welder, whose titanium sonotrode is integrated on a filament winding machine. During winding, the commingled roving is at the same time in contact with the mandrel and the horn. The intermolecular friction generated by ultrasound is able to melt the thermoplastic matrix and impregnate the reinforcement fibers. The heat transfer phenomena occurring during the in situ consolidation were simulated solving by finite element (FE) analysis an energy balance accounting for the heat generated by ultrasonic waves and the melting characteristics of the matrix. To this aim, a calorimetric characterization of the thermoplastic matrix has been carried out to obtain the input parameters for the model. The FE analysis has enabled to predict the temperature distribution in the composite during heating and cooling The simulation results have been validated by the measurement of the temperature evolution during ultrasonic consolidation. The reliability of the developed consolidation equipment was proved by producing hoop wound cylinder prototypes using commingled continuous E-glass rovings and Polypropylene (PP) filaments. The consolidated composite cylinders are characterized by high mechanical properties, with values comparable with the theoretical ones predicted by the micromechanical analysis.

  2. Distribution of Oil in a PP/EPDM Thermoplastic Elastomer

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yutaka; Okada, Tetsuo; Inoue, Takashi

    Distribution of oil in a commercial PP(polypropylene)/EPDM(ethylene-propyrene-diene rubber) thermoplastic elastomer was analyzed by light scattering. It was shown that the oil preferentially stays in EPDM particles at low temperatures and it migrates to PP matrix at high temperatures. That is, the oil is expected to play a dual role; softener at ambient temperature and plasticizer at processing temperature. The temperature dependence of oil distribution was nicely interpreted by a thermodynamic discussion.

  3. Poly(hydroxy amide ethers): New high-barrier thermoplastics

    SciTech Connect

    Brennan, D.J.; White, J.E.; Haag, A.P.; Kram, S.L.; Brown, C.N.; Pikulin, S.

    1993-12-31

    Over the last several years the authors have been involved in a program to prepare thermoplastic resins having high-barrier to oxygen, good processing characteristics, and excellent mechanical properties. One result of these efforts has been the synthesis of poly(hydroxy amide ethers), a new class of high-barrier thermoplastics. These high-molecular-weight polymers are formed by reactions of aromatic diglycidyl ethers with amide-containing bisphenols in high-boiling alcohol solvent. The polymers have good to outstanding barrier to oxygen, with oxygen transmission rates (O{sub 2}TR) of 0.1 - 5.0 cc-mil/100 in{sup 2}-atm-day (barrier units or BU) at high relative humidity (60-80%). Glass transition temperatures (Tg) of the polymers range from 80 to 200{degrees}C. The example shown combines the Tg of an engineering thermoplastic (152{degrees}C) with good barrier (1.5 BU) and mechanical performance. The effect that structure has on O{sub 2}TR and Tg of the polymers will be discussed. Physical properties of selected examples will also be presented.

  4. Process for preparing tapes from thermoplastic polymers and carbon fibers

    NASA Technical Reports Server (NTRS)

    Chung, Tai-Shung (Inventor); Furst, Howard (Inventor); Gurion, Zev (Inventor); McMahon, Paul E. (Inventor); Orwoll, Richard D. (Inventor); Palangio, Daniel (Inventor)

    1986-01-01

    The instant invention involves a process for use in preparing tapes or rovings, which are formed from a thermoplastic material used to impregnate longitudinally extended bundles of carbon fibers. The process involves the steps of (a) gas spreading a tow of carbon fibers; (b) feeding the spread tow into a crosshead die; (c) impregnating the tow in the die with a thermoplastic polymer; (d) withdrawing the impregnated tow from the die; and (e) gas cooling the impregnated tow with a jet of air. The crosshead die useful in the instant invention includes a horizontally extended, carbon fiber bundle inlet channel, means for providing melted polymer under pressure to the die, means for dividing the polymeric material flowing into the die into an upper flow channel and a lower flow channel disposed above and below the moving carbon fiber bundle, means for applying the thermoplastic material from both the upper and lower channels to the fiber bundle, and means for withdrawing the resulting tape from the die.

  5. Block copolymer self-assembly fundamentals and applications in formulation of nano-structured fluids

    NASA Astrophysics Data System (ADS)

    Sarkar, Biswajit

    Dispersions of nanoparticles in polymer matrices form hybrid materials that can exhibit superior structural and functional properties and find applications in e.g. thermo-plastics, electronics, polymer electrolytes, catalysis, paint formulations, and drug delivery. Control over the particle location and orientation in the polymeric matrices are essential in order to realize the enhanced mechanical, electrical, and optical properties of the nanohybrids. Block copolymers, composed of two or more different monomers, are promising for controlling particle location and orientation because of their ability to organize into ordered nanostructures. Fundamental questions pertaining to nanoparticle-polymer interfacial interactions remain open and formulate the objectives of our investigation. Particle-polymer enthalpic and entropic interactions control the nanoparticle dispersion in polymer matrices. Synthetic chemical methods for modifying the particle surface in order to control polymer-particle interactions are involved and large scale production is not possible. In the current approach, a physical method is employed to control polymer-particle interactions. The use of commercially available solvents is found to be effective in modifying particle-polymer interfacial interactions. The approach is applicable to a wide range of particle-polymer systems and can thereby enable large scale processing of polymer nanohybrids. The systems of silica nanoparticles dispersed in long-range or short-range self-assembled structures of aqueous poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronics) is considered here. The effect of various parameters such as the presence of organic solvents, pH, and particle size on the block copolymer organization and the ensuing particle-polymer interactions are investigated. Favorable surface interactions between the deprotonated silica nanoparticle and PEO-rich domain facilitate particle

  6. Impacts of Repeat Unit Structure and Copolymer Architecture on Thermal and Solution Properties in Homopolymers, Copolymers, and Copolymer Blends

    NASA Astrophysics Data System (ADS)

    Marrou, Stephen Raye

    Gradient copolymers are a relatively new type of copolymer architecture in which the distribution of comonomers gradually varies over the length of the copolymer chain, resulting in a number of unusual properties derived from the arrangement of repeat units. For example, nanophase-segregated gradient copolymers exhibit extremely broad glass transition temperatures (Tgs) resulting from the wide range of compositions present in the nanostructure. This dissertation presents a number of studies on how repeat unit structure and copolymer architecture dictate bulk and solution properties, specifically taking inspiration from the gradient copolymer architecture and comparing the response from this compositionally heterogeneous material to other more conventional materials. The glass transition behavior of a range of common homopolymers was studied to determine the effects of subunit structure on Tg breadth, observing a significant increase in T g breadth with increasing side chain length in methacrylate-based homopolymers and random copolymers. Additionally, increasing the composition distribution of copolymers, either by blending individual random copolymers of different overall composition or synthesizing random copolymers to high conversion, resulted in significant increases to Tg breadth. Plasticization of homopolymers and random copolymers with low molecular weight additives also served to increase the Tg breadth; the most dramatic effect was observed in the selective plasticization of a styrene/4-vinylpyridine gradient copolymer with increases in T g breadth to values above 100 °C. In addition, the effects of repeat unit structure and copolymer architecture on other polymer properties besides Tg were also investigated. The intrinsic fluorescence of styrene units in styrene-containing copolymers was studied, noting the impact of repeat unit structure and copolymer architecture on the resulting fluorescence spectra in solution. The impact of repeat unit structure on

  7. Protein-like copolymers: computer simulation

    NASA Astrophysics Data System (ADS)

    Khokhlov, Alexei R.; Khalatur, Pavel G.

    The notion of protein-like AB copolymers is introduced. Such copolymers can be generated with the help of the “ instant image” of a dense homopolymer globule by assigning that the monomeric units closer to the globular surface are of A type, while the core is formed by the B type units. After that the primary structure of the chain is fixed, and one introduces different interaction potentials for A and B units. In doing so, we have in mind mainly aqueous systems and analogy with globular proteins, therefore A units are regarded as hydrophilic, and B units as hydrophobic. By means of Monte Carlo simulation using the bond fluctuation model we study the coil-globule transition for a protein-like copolymer upon the increase of attraction of hydrophobic B units, and compare the results with those for random AB copolymers. From the analysis of the primary structure of protein-like copolymers one can see that the “ degree of blockiness” of the protein-like sequence is higher than for random copolymers, therefore the copolymers with the “ random-block” primary structure are generated for comparison as well (the average length of A and B sequences being the same as for protein-like copolymers). It is shown that the coil-globule transition in protein-like copolymers occurs at higher temperatures, is more abrupt and has faster kinetics than for random copolymers with the same A/ B composition and for random-block copolymers with the same A/ B composition and “ degree of blockiness”. The globules of protein-like copolymers exhibit a dense micelle-like core of hydrophobic B units stabilized by the long dangling loops of hydrophilic A units. Apparently, a protein-like copolymer “ inherits” some of the properties of the “ parent globule” which is reflected in the special long-range correlations in primary structure.

  8. Bioinspired catecholic copolymers for antifouling surface coatings.

    PubMed

    Cho, Joon Hee; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2013-05-01

    We report here a synthetic approach to prepare poly(methyl methacrylate)-polydopamine diblock (PMMA-PDA) and triblock (PDA-PMMA-PDA) copolymers combining mussel-inspired catecholic oxidative chemistry and atom transfer radical polymerization (ATRP). These copolymers display very good solubility in a range of organic solvents and also a broad band photo absorbance that increases with increasing PDA content in the copolymer. Spin-cast thin films of the copolymer were stable in water and showed a sharp reduction (by up to 50%) in protein adsorption compared to those of neat PMMA. Also the peak decomposition temperature of the copolymers was up to 43°C higher than neat PMMA. The enhanced solvent processability, thermal stability and low protein adsorption characteristics of this copolymer makes it attractive for variety of applications including antifouling coatings on large surfaces such as ship hulls, buoys, and wave energy converters.

  9. In situ development of self-reinforced cellulose nanocrystals based thermoplastic elastomers by atom transfer radical polymerization.

    PubMed

    Yu, Juan; Wang, Chunpeng; Wang, Jifu; Chu, Fuxiang

    2016-05-05

    Recently, the utilization of cellulose nanocrystals (CNCs) as a reinforcing material has received a great attention due to its high elastic modulus. In this article, a novel strategy for the synthesis of self-reinforced CNCs based thermoplastic elastomers (CTPEs) is presented. CNCs were first surface functionalized with an initiator for surface-initiated atom transfer radical polymerization (SI-ATRP). Subsequently, SI-ATRP of methyl methacrylate (MMA) and butyl acrylate (BA) was carried out in the presence of sacrificial initiator to form CTPEs in situ. The CTPEs together with the simple blends of CNCs and linear poly(MMA-co-BA) copolymer (P(MMA-co-BA)) were characterized for comparative study. The results indicated that P(MMA-co-BA) was successfully grafted onto the surface of CNCs and the compatibility between CNCs and the polymer matrix in CTPEs was greatly enhanced. Specially, the CTPEs containing 2.15wt% CNCs increased Tg by 19.2°C and tensile strength by 100% as compared to the linear P(MMA-co-BA). Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Multi-shape memory polymers achieved by the spatio-assembly of 3D printable thermoplastic building blocks.

    PubMed

    Li, Hongze; Gao, Xiang; Luo, Yingwu

    2016-04-07

    Multi-shape memory polymers were prepared by the macroscale spatio-assembly of building blocks in this work. The building blocks were methyl acrylate-co-styrene (MA-co-St) copolymers, which have the St-block-(St-random-MA)-block-St tri-block chain sequence. This design ensures that their transition temperatures can be adjusted over a wide range by varying the composition of the middle block. The two St blocks at the chain ends can generate a crosslink network in the final device to achieve strong bonding force between building blocks and the shape memory capacity. Due to their thermoplastic properties, 3D printing was employed for the spatio-assembly to build devices. This method is capable of introducing many transition phases into one device and preparing complicated shapes via 3D printing. The device can perform a complex action via a series of shape changes. Besides, this method can avoid the difficult programing of a series of temporary shapes. The control of intermediate temporary shapes was realized via programing the shapes and locations of building blocks in the final device.

  11. Properties of novel bone hemostat prepared using sugar-modified hydroxyapatite, phosphoryl oligosaccharides of calcium and thermoplastic resin

    NASA Astrophysics Data System (ADS)

    Mimira, Tokio; Umeda, Tomohiro; Musha, Yoshiro; Itatani, Kiyoshi

    2013-12-01

    A novel hemostatic agent was prepared using phosphoryl oligosaccharides of calcium (POs-Ca), hydroxyapatite (Ca10(PO4)6(OH)2; HAp) obtained by the hydrolysis of POs-Ca or sugar-containing HAp (s-HAp; 60.3 mass% calcium-deficient HAp and 39.5 mass% organic materials, Ca/P ratio = 1.56) and thermoplastic resin (the mixture of random copolymer of ethylene oxide/propylene oxide (EPO) and polyethylene oxide (EO); EPO : EO : water = 25 : 15 : 60 (mass ratio); 25EPO-15EO). The gel formed by mixing 25EPO-15EO with water (25EPO-15EO/water mass ratio: 0.20) was flash frozen at -80°C, freeze-dried at -50°C for 15 h and then ground using mixer. The consistency conditions of hemostats mixed with POs-Ca or s-HAp were optimized for the practical uses. The mean stanching times of hemostats were: s-HAp/25EPO-15EO (8.2 h; s-HAp/25EPO-15EO = 0.20) > 25EPO-15EO (5.3 h) > POs-Ca/25EPO-15EO (4.7 h; POs-Ca/25EPO-15EO = 0.20). The gentamicin, a typical antibiotic agent, loaded s-HAp/25EPO-15EO composite hemostat showed the steady state releasing in phosphate buffered saline till 10 h immersion at 37.0°C.

  12. Fracture Toughness of Carbon Fiber Composites Containing Various Fiber Sizings and a Puncture Self-Healing Thermoplastic Matrix

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Grimsley, Brian W.; Ratcliffe, James G.; Gordon, Keith L.; Smith, Joseph G.; Siochi, Emilie J.

    2015-01-01

    Ongoing efforts at NASA Langley Research Center (LaRC) have resulted in the identification of several commercially available thermoplastic resin systems which self-heal after ballistic impact and through penetration. One of these resins, polybutylene graft copolymer (PBg), was selected as a matrix for processing with unsized carbon fibers to fabricate reinforced composites for further evaluation. During process development, data from thermo-physical analyses was utilized to determine a processing cycle to fabricate laminate panels, which were analyzed by photo microscopy and acid digestion. The process cycle was further optimized based on these results to fabricate panels for mechanical property characterization. The results of the processing development effort of this composite material, as well as the results of the mechanical property characterization, indicated that bonding between the fiber and PBg was not adequate. Therefore, three sizings were investigated in this work to assess their potential to improve fiber/matrix bonding compared to previously tested unsized IM7 fiber. Unidirectional prepreg was made at NASA LaRC from three sized carbon fibers and utilized to fabricate test coupons that were tested in double cantilever beam configurations to determine GIc fracture toughness.

  13. Crystalline Imide/Arylene Ether Copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Hergenrother, Paul M.; Bass, Robert G.

    1991-01-01

    Series of imide/arylene ether block copolymers prepared by using arylene ether blocks to impart low melt viscosity, and imide blocks to provide high strength and other desirable mechanical properties. Work represents extension of LAR-14159 on imide/arylene ether copolymers in form of films, moldings, adhesives, and composite matrices. Copolymers potentially useful in variety of high-temperature aerospace and microelectronic applications.

  14. Effects of block copolymer self-assembly on optical anisotropy in azobenzene-containing PS-b-PMMA films.

    PubMed

    Orofino, A B; Camezzana, M F; Galante, M J; Oyanguren, P A; Zucchi, I A

    2012-03-23

    Polystyrene-b-polymethylmethacrylate (PS-b-PMMA) was selected as the host for 4-(4-nitrophenylazo)aniline (Disperse Orange 3, DO3) based on a previous study of DO3/PMMA and DO3/PS binary blends. Selective location of DO3 into the PMMA block of the copolymer was expected during self-assembly of the block copolymer since a preferential interaction of DO3 with PMMA has been demonstrated. However, surface segregation of DO3 was found during the thermal annealing used to nanostructure the copolymer. To avoid this, a thermoplastic polymer (Azo-TP) was synthesized from the bulk reaction of DO3 and diglycidyl ether of bisphenol A (DGEBA). The choice of DGEBA as a co-reactant was an attempt to encourage the selective location of azo groups in the PMMA phase of PS-b-PMMA. An inspection of solutions of Azo-TP in PS and PMMA, corroborates the preferential affinity of Azo-TP for PMMA. The Azo-TP could be satisfactorily dissolved in PS-b-PMMA. We have investigated the growth and decay processes of the optically induced birefringence in films of PS-b-PMMA containing 12 wt% Azo-TP. The resulting materials showed a good photoinduced time response, high maximum birefringence and an elevated fraction of remnant anisotropy.

  15. 40 CFR Table 5 to Subpart Jjj of... - Group 1 Storage Vessels at New Affected Sources Producing the Listed Thermoplastics

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Group 1 Storage Vessels at New Affected Sources Producing the Listed Thermoplastics 5 Table 5 to Subpart JJJ of Part 63 Protection of Environment... Storage Vessels at New Affected Sources Producing the Listed Thermoplastics Thermoplastic Chemical a...

  16. 40 CFR Table 3 to Subpart Jjj of... - Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics 3 Table 3 to Subpart JJJ of Part 63 Protection of... Thermoplastics Thermoplastic Chemical a Vessel capacity (cubic meters) Vapor pressure b (kilopascals) ASA/AMSAN c...

  17. 40 CFR Table 3 to Subpart Jjj of... - Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 12 2013-07-01 2013-07-01 false Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics 3 Table 3 to Subpart JJJ of Part 63 Protection of... Thermoplastics Thermoplastic Chemical a Vessel capacity (cubic meters) Vapor pressure b (kilopascals) ASA/AMSAN c...

  18. 40 CFR Table 3 to Subpart Jjj of... - Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Affected Sources Producing the Listed Thermoplastics 3 Table 3 to Subpart JJJ of Part 63 Protection of... 63—Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics Thermoplastic Chemical a Vessel capacity (cubic meters) Vapor pressure b (kilopascals) ASA/AMSAN c styrene...

  19. 40 CFR Table 3 to Subpart Jjj of... - Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Affected Sources Producing the Listed Thermoplastics 3 Table 3 to Subpart JJJ of Part 63 Protection of... 63—Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics Thermoplastic Chemical a Vessel capacity (cubic meters) Vapor pressure b (kilopascals) ASA/AMSAN c styrene...

  20. 40 CFR Table 3 to Subpart Jjj of... - Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Affected Sources Producing the Listed Thermoplastics 3 Table 3 to Subpart JJJ of Part 63 Protection of... 63—Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics Thermoplastic Chemical a Vessel capacity (cubic meters) Vapor pressure b (kilopascals) ASA/AMSAN c styrene...

  1. Hydrothermal Conditioning of Physical Hydrogels Prepared from a Midblock-Sulfonated Multiblock Copolymer.

    PubMed

    Mineart, Kenneth P; Dickerson, Joshua D; Love, Dillon M; Lee, Byeongdu; Zuo, Xiaobing; Spontak, Richard J

    2017-03-01

    Since nanostructured amphiphilic macromolecules capable of affording high ion and water transport are becoming increasingly important in a wide range of contemporary energy and environmental technologies, the swelling kinetics and temperature dependence of water uptake are investigated in a series of midblock-sulfonated thermoplastic elastomers. Upon self-assembly, these materials maintain a stable hydrogel network in the presence of a polar liquid. In this study, real-time water-sorption kinetics in copolymer films prepared by different casting solvents are elucidated by synchrotron small-angle X-ray scattering and gravimetric measurements, which directly correlate nanostructural changes with macroscopic swelling to establish fundamental structure-property behavior. By monitoring the equilibrium swelling capacity of these materials over a range of temperatures, an unexpected transition in the vicinity of 50 °C has been discovered. Depending on copolymer morphology and degree of sulfonation, hydrothermal conditioning of specimens to temperatures above this transition permits retention of superabsorbent swelling at ambient temperature. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for non metal clasp denture.

    PubMed

    Jang, Dae-Eun; Lee, Ji-Young; Jang, Hyun-Seon; Lee, Jang-Jae; Son, Mee-Kyoung

    2015-08-01

    The aim of this study was to compare the color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for the non-metal clasp dentures to those of thermoplastic polyamide and conventional heat-polymerized denture base resins. Three types of denture base resin, which are conventional heat-polymerized acrylic resin (Paladent 20), thermoplastic polyamide resin (Bio Tone), thermoplastic acrylic resin (Acrytone) were used as materials for this study. One hundred five specimens were fabricated. For the color stability test, specimens were immersed in the coffee and green tee for 1 and 8 weeks. Color change was measured by spectrometer. Water sorption was tested after 1 and 8 weeks immersion in the water. For the test of cytotoxicity, cell viability assay was measured and cell attachment was analyzed by FE-SEM. All types of denture base resin showed color changes after 1 and 8 weeks immersion. However, there was no significant difference between denture base resins. All specimens showed significant color changes in the coffee than green tee. In water sorption test, thermoplastic acrylic resin showed lower values than conventional heat-polymerized acrylic resin and thermoplastic polyamide resin. Three types of denture base showed low cytotoxicity in cell viability assay. Thermoplastic acrylic resin showed the similar cell attachment but more stable attachment than conventional heat-polymerized acrylic resin. Thermoplastic acrylic resin for the non-metal clasp denture showed acceptable color stability, water sorption and cytotoxicity. To verify the long stability in the mouth, additional in vitro studies are needed.

  3. Thermal Degradation, Mechanical Properties and Morphology of Wheat Straw Flour Filled Recycled Thermoplastic Composites

    PubMed Central

    Mengeloglu, Fatih; Karakus, Kadir

    2008-01-01

    Thermal behaviors of wheat straw flour (WF) filled thermoplastic composites were measured applying the thermogravimetric analysis and differential scanning calorimetry. Morphology and mechanical properties were also studied using scanning electron microscope and universal testing machine, respectively. Presence of WF in thermoplastic matrix reduced the degradation temperature of the composites. One for WF and one for thermoplastics, two main decomposition peaks were observed. Morphological study showed that addition of coupling agent improved the compatibility between WFs and thermoplastic. WFs were embedded into the thermoplastic matrix indicating improved adhesion. However, the bonding was not perfect because some debonding can also be seen on the interface of WFs and thermoplastic matrix. In the case of mechanical properties of WF filled recycled thermoplastic, HDPE and PP based composites provided similar tensile and flexural properties. The addition of coupling agents improved the properties of thermoplastic composites. MAPE coupling agents performed better in HDPE while MAPP coupling agents were superior in PP based composites. The composites produced with the combination of 50-percent mixture of recycled HDPE and PP performed similar with the use of both coupling agents. All produced composites provided flexural properties required by the ASTM standard for polyolefin-based plastic lumber decking boards. PMID:27879719

  4. Determination of carbon fiber adhesion to thermoplastic polymers using the single fiber/matrix tensile test

    NASA Technical Reports Server (NTRS)

    Bascom, W. D.; Cordner, L. W.; Hinkley, J. L.; Johnston, N. J.

    1986-01-01

    The single fiber adhesion shear test has been adapted to testing the adhesion between carbon fiber and thermoplastic polymers. Tests of three thermoplastics, polycarbonate, polyphenylene oxide and polyetherimide indicate the shear adhesion strength is significantly less than of an epoxy polymer to the same carbon fiber.

  5. Thermoplastic composites: Recycling. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1995-12-01

    The bibliography contains citations concerning the recycling of thermoplastic composites. Multilayer thermoplastics, high density polyethylenes, polypropylenes, polycarbonates, and polyamides reinforced with fibers are considered. Granulators, recovery plants, and gasification of plastic waste are among the recycling techniques discussed.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  6. Thermoplastic composites: Recycling. (Latest citations from the Rubber and Plastics Research Association database). NewSearch

    SciTech Connect

    Not Available

    1994-11-01

    The bibliography contains citations concerning the recycling of thermoplastic composites. Multilayer thermoplastics, high density polyethylenes, polypropylenes, polycarbonates, and polyamides reinforced with fibers are considered. Granulators, recovery plants, and gasification of plastic waste are among the recycling techniques discussed. (Contains a minimum of 218 citations and includes a subject term index and title list.)

  7. Thermoplastic composites: Recycling. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1996-11-01

    The bibliography contains citations concerning the recycling of thermoplastic composites. Multilayer thermoplastics, high density polyethylenes, polypropylenes, polycarbonates, and polyamides reinforced with fibers are considered. Granulators, recovery plants, and gasification of plastic waste are among the recycling techniques discussed.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  8. Thermoplastic composites: Recycling. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    Not Available

    1994-03-01

    The bibliography contains citations concerning the recycling of thermoplastic composites. Multilayer thermoplastics, high density polyethylenes, polypropylenes, polycarbonates, and polyamides reinforced with fibers are considered. Granulators, recovery plants, and gasification of plastic waste are among the recycling techniques discussed. (Contains a minimum of 182 citations and includes a subject term index and title list.)

  9. Recycling of ligno-cellulosic and polyethylene wastes from agricultural operations in thermoplastic composites

    USDA-ARS?s Scientific Manuscript database

    In the US, wood plastic composites (WPC) represent one of the successful markets for natural fiber-filled thermoplastic composites. The WPC typically use virgin or recycled thermoplastic as the substrate and wood fiber as the filler. A major application of the WPC is in non-structural building appli...

  10. Effects of weathering on color loss of natural fiber : thermoplastic composites

    Treesearch

    Robert H. Falk; Colin. Felton; Thomas. Lundin

    2000-01-01

    The technology currently exists to manufacture natural fiber-thermoplastic composites from recycled materials. Development of commodity building products from these composites would open huge markets for waste-based materials in the United States. To date, the construction industry has only accepted wood-thermoplastic composite lumber and only for limited applications...

  11. Effects of weathering on color loss of natural fiber thermoplastic composites

    Treesearch

    R.H. Falk; C. Felton; T. Lundin

    2001-01-01

    The technology currently exists to manufacture natural fiber thermoplastic composites from recycled materials. Development of commodity-building products from these composites would open up huge markets for waste-based materials in the US. To date, the construction industry has only accepted wood thermoplastic composite lumber (and only for limited applications). In...

  12. Phase Behavior of Symmetric Sulfonated Block Copolymers

    SciTech Connect

    Park, Moon Jeong; Balsara, Nitash P.

    2008-08-21

    Phase behavior of poly(styrenesulfonate-methylbutylene) (PSS-PMB) block copolymers was studied by varying molecular weight, sulfonation level, and temperature. Molecular weights of the copolymers range from 2.9 to 117 kg/mol. Ordered lamellar, gyroid, hexagonally perforated lamellae, and hexagonally packed cylinder phases were observed in spite of the fact that the copolymers are nearly symmetric with PSS volume fractions between 0.45 and 0.50. The wide variety of morphologies seen in our copolymers is inconsistent with current theories on block copolymer phase behavior such as self-consistent field theory. Low molecular weight PSS-PMB copolymers (<6.2 kg/mol) show order-order and order-disorder phase transitions as a function of temperature. In contrast, the phase behavior of high molecular weight PSS-PMB copolymers (>7.7 kg/mol) is independent of temperature. Due to the large value of Flory-Huggins interaction parameter, x, between the sulfonated and non-sulfonated blocks, PSS-PMB copolymers with PSS and PMB molecular weights of 1.8 and 1.4 kg/mol, respectively, show the presence of an ordered gyroid phase with a 2.5 nm diameter PSS network. A variety of methods are used to estimate x between PSS and PMB chains as a function of sulfonation level. Some aspects of the observed phase behavior of PSS-PMB copolymers can be rationalized using x.

  13. Self-assembly of Random Copolymers

    PubMed Central

    Li, Longyu; Raghupathi, Kishore; Song, Cunfeng; Prasad, Priyaa; Thayumanavan, S.

    2014-01-01

    Self-assembly of random copolymers has attracted considerable attention recently. In this feature article, we highlight the use of random copolymers to prepare nanostructures with different morphologies and to prepare nanomaterials that are responsive to single or multiple stimuli. The synthesis of single-chain nanoparticles and their potential applications from random copolymers are also discussed in some detail. We aim to draw more attention to these easily accessible copolymers, which are likely to play an important role in translational polymer research. PMID:25036552

  14. Copolymers of fluorinated polydienes and sulfonated polystyrene

    DOEpatents

    Mays, Jimmy W.; Gido, Samuel P.; Huang, Tianzi; Hong, Kunlun

    2009-11-17

    Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

  15. Scanning probe block copolymer lithography

    PubMed Central

    Chai, Jinan; Huo, Fengwei; Zheng, Zijian; Giam, Louise R.; Shim, Wooyoung; Mirkin, Chad A.

    2010-01-01

    Integration of individual nanoparticles into desired spatial arrangements over large areas is a prerequisite for exploiting their unique electrical, optical, and chemical properties. However, positioning single sub-10-nm nanoparticles in a specific location individually on a substrate remains challenging. Herein we have developed a unique approach, termed scanning probe block copolymer lithography, which enables one to control the growth and position of individual nanoparticles in situ. This technique relies on either dip-pen nanolithography (DPN) or polymer pen lithography (PPL) to transfer phase-separating block copolymer inks in the form of 100 or more nanometer features on an underlying substrate. Reduction of the metal ions via plasma results in the high-yield formation of single crystal nanoparticles per block copolymer feature. Because the size of each feature controls the number of metal atoms within it, the DPN or PPL step can be used to control precisely the size of each nanocrystal down to 4.8 ± 0.2 nm. PMID:21059942

  16. Interfaces between Block Copolymer Domains

    NASA Astrophysics Data System (ADS)

    Kim, Jaeup; Jeong, Seong-Jun; Kim, Sang Ouk

    2011-03-01

    Block copolymers naturally form nanometer scale structures which repeat their geometry on a larger scale. Such a small scale periodic pattern can be used for various applications such as storage media, nano-circuits and optical filters. However, perfect alignment of block copolymer domains in the macroscopic scale is still a distant dream. The nanostructure formation usually occurs with spontaneously broken symmetry; hence it is easily infected by topological defects which sneak in due to entropic fluctuation and incomplete annealing. Careful annealing can gradually reduce the number of defects, but once kinetically trapped, it is extremely difficult to remove all the defects. One of the main reasons is that the defect finds a locally metastable morphology whose potential depth is large enough to prohibit further morphology evolution. In this work, the domain boundaries between differently oriented lamellar structures in thin film are studied. For the first time, it became possible to quantitatively study the block copolymer morphology in the transitional region, and it was shown that the twisted grain boundary is energetically favorable compared to the T-junction grain boundary. [Nano Letters, 9, 2300 (2010)]. This theoretical method successfully explained the experimental results.

  17. Use of Melt Flow Rate Test in Reliability Study of Thermoplastic Encapsulation Materials in Photovoltaic Modules

    SciTech Connect

    Moseley, J.; Miller, D.; Shah, Q.-U.-A. S. J.; Sakurai, K.; Kempe, M.; Tamizhmani, G.; Kurtz, S.

    2011-10-01

    Use of thermoplastic materials as encapsulants in photovoltaic (PV) modules presents a potential concern in terms of high temperature creep, which should be evaluated before thermoplastics are qualified for use in the field. Historically, the issue of creep has been avoided by using thermosetting polymers as encapsulants, such as crosslinked ethylene-co-vinyl acetate (EVA). Because they lack crosslinked networks, however, thermoplastics may be subject to phase transitions and visco-elastic flow at the temperatures and mechanical stresses encountered by modules in the field, creating the potential for a number of reliability and safety issues. Thermoplastic materials investigated in this study include PV-grade uncured-EVA (without curing agents and therefore not crosslinked); polyvinyl butyral (PVB); thermoplastic polyurethane (TPU); and three polyolefins (PO), which have been proposed for use as PV encapsulation. Two approaches were used to evaluate the performance of these materials as encapsulants: module-level testing and a material-level testing.

  18. Synthesis and Characterization of Graft Copolymers Poly(isoprene-g-styrene) of High Molecular Weight by a Combination of Anionic Polymerization and Emulsion Polymerization

    SciTech Connect

    Wang, Wenwen; Wang, Weiyu; Li, Hui; Lu, Xinyi; Chen, Jihua; Kang, Nam-goo; Zhang, Qiuyu; Mays, Jimmy

    2015-01-14

    In this study, high molecular weight “comb-shaped” graft copolymers, poly(isoprene-g-styrene), with polyisoprene as the backbone and polystyrene as side chains, were synthesized via free radical emulsion polymerization by copolymerization of isoprene with a polystyrene macromonomer synthesized using anionic polymerization. A small amount of toluene was used in order to successfully disperse the macromonomer. Both a redox and thermal initiation system were used in the emulsion polymerization, and the latex particle size and distribution were investigated by dynamic light scattering. The structural characteristics of the macromonomer and comb graft copolymers were investigated through use of size exclusion chromatography, spectroscopy, microscopy, thermal analysis, and rheology. While the macromonomer was successfully copolymerized to obtain the desired multigraft copolymers, small amounts of unreacted macromonomer remained in the products, reflecting its reduced reactivity due to steric effects. Nevertheless, the multigraft copolymers obtained were very high in molecular weight (5–12 × 105 g/mol) and up to 10 branches per chain, on average, could be incorporated. A material incorporating 29 wt% polystyrene exhibits a disordered microphase separated morphology and elastomeric properties. As a result, these materials show promise as new, highly tunable, and potentially low cost thermoplastic elastomers.

  19. Synthesis and Characterization of Graft Copolymers Poly(isoprene-g-styrene) of High Molecular Weight by a Combination of Anionic Polymerization and Emulsion Polymerization

    DOE PAGES

    Wang, Wenwen; Wang, Weiyu; Li, Hui; ...

    2015-01-14

    In this study, high molecular weight “comb-shaped” graft copolymers, poly(isoprene-g-styrene), with polyisoprene as the backbone and polystyrene as side chains, were synthesized via free radical emulsion polymerization by copolymerization of isoprene with a polystyrene macromonomer synthesized using anionic polymerization. A small amount of toluene was used in order to successfully disperse the macromonomer. Both a redox and thermal initiation system were used in the emulsion polymerization, and the latex particle size and distribution were investigated by dynamic light scattering. The structural characteristics of the macromonomer and comb graft copolymers were investigated through use of size exclusion chromatography, spectroscopy, microscopy, thermalmore » analysis, and rheology. While the macromonomer was successfully copolymerized to obtain the desired multigraft copolymers, small amounts of unreacted macromonomer remained in the products, reflecting its reduced reactivity due to steric effects. Nevertheless, the multigraft copolymers obtained were very high in molecular weight (5–12 × 105 g/mol) and up to 10 branches per chain, on average, could be incorporated. A material incorporating 29 wt% polystyrene exhibits a disordered microphase separated morphology and elastomeric properties. As a result, these materials show promise as new, highly tunable, and potentially low cost thermoplastic elastomers.« less

  20. Additive Manufacturing of Thermoplastic Matrix Composites Using Ultrasonics

    NASA Astrophysics Data System (ADS)

    Olson, Meghan

    Advanced composite materials have great potential for facilitating energy efficient product design and their manufacture if improvements are made to current composite manufacturing processes. This thesis focuses on the development of a novel manufacturing process for thermoplastic composite structures entitled Laser-Ultrasonic Additive Manufacturing ('LUAM'), which is intended to combine the benefits of laser processing technology, developed by Automated Dynamics Inc., with ultrasonic bonding technology that is used commercially for unreinforced polymers. These technologies used together have the potential to significantly reduce the energy consumption and void content of thermoplastic composites made using Automated Fiber Placement (AFP). To develop LUAM in a methodical manner with minimal risk, a staged approach was devised whereby coupon-level mechanical testing and prototyping utilizing existing equipment was accomplished. Four key tasks have been identified for this effort: Benchmarking, Ultrasonic Compaction, Laser Assisted Ultrasonic Compaction, and Demonstration and Characterization of LUAM. This thesis specifically addresses Tasks 1 and 2, i.e. Benchmarking and Ultrasonic Compaction, respectively. Task 1, fabricating test specimens using two traditional processes (autoclave and thermal press) and testing structural performance and dimensional accuracy, provide results of a benchmarking study by which the performance of all future phases will be gauged. Task 2, fabricating test specimens using a non-traditional process (ultrasonic conpaction) and evaluating in a similar fashion, explores the the role of ultrasonic processing parameters using three different thermoplastic composite materials. Further development of LUAM, although beyond the scope of this thesis, will combine laser and ultrasonic technology and eventually demonstrate a working system.

  1. Tough, high performance, addition-type thermoplastic polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1992-01-01

    A tough, high performance polyimide is provided by reacting a triple bond conjugated with an aromatic ring in a bisethynyl compound with the active double bond in a compound containing a double bond activated toward the formation of a Diels-Adler type adduct, especially a bismaleimide, a biscitraconimide, or a benzoquinone, or mixtures thereof. Addition curing of this product produces a high linear polymeric structure and heat treating the highly linear polymeric structure produces a thermally stable aromatic addition-type thermoplastic polyimide, which finds utility in the preparation of molding compounds, adhesive compositions, and polymer matrix composites.

  2. Thermoplastic adhesives based on 4,4'-isophthaloyldiphthalic anhydride (IDPA)

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.; Stclair, Terry L.; Pratt, J. Richard

    1988-01-01

    Thermoplastic polyimides were prepared and evaluated as adhesives. These materials are based on 4,4'-isophthaloyldiphathalic anhydride (IDAP) and either metaphenylene diamine (MPD) or 3,3'-diaminobenzophenone (DBAP). Both polymers exhibit excellent adhesive properties; however, the IDPA-MPD is the more attractive system because of a combination of high mechanical and physical properties as well as being made from commercially attractive monomers. The IDPA-MPD is an isomeric form of the commercially available adhesive and matrix resin, LARC-TPI and both systems have the same glass transition temperature and exhibit similar adhesive properties.

  3. Time Issues in Semi-Crystalline Thermoplastics Processing

    NASA Astrophysics Data System (ADS)

    Iannone, Michele

    2010-06-01

    Cooling rate of semicrystalline thermoplastic (PEEK) based composite parts has been assessed by means of a thermal flow model. Cold tool thermoforming was found suitable for thin parts, but the use of a preheated tool is suggested. Cooling rate is critical for automated lay-up; consequently the optimization of this technique requires the use of a complex apparatus, able to provide both heating of the part during lay-up and a control of the cooling rate. Alternatively a modified cooling rate vs. crystallinity behavior of the material must be achieved.

  4. Nonlinear mechanical behavior of thermoplastic matrix materials for advanced composites

    NASA Technical Reports Server (NTRS)

    Arenz, R. J.; Landel, R. F.

    1989-01-01

    Two recent theories of nonlinear mechanical response are quantitatively compared and related to experimental data. Computer techniques are formulated to handle the numerical integration and iterative procedures needed to solve the associated sets of coupled nonlinear differential equations. Problems encountered during these formulations are discussed and some open questions described. Bearing in mind these cautions, the consequences of changing parameters that appear in the formulations on the resulting engineering properties are discussed. Hence, engineering approaches to the analysis of thermoplastic matrix material can be suggested.

  5. Three-dimensional microstructure characterisation of thermoplastic polyolefin blends.

    PubMed

    Lin, J-C; Huang, Y; Harris, J; Weinlander, B; Jones, M A

    2017-09-01

    The size, shape and distribution of different phases in thermoplastic polyolefin (TPO) blends and composites are critical to the properties of the materials, but can be difficult to characterise. Here we report the combination of heavy metal staining and focused ion beam - scanning electron microscopy (FIB-SEM) to reveal the three-dimensional (3D) structure of an elastomer-modified poly(propylene) and a talc filled elastomer-modified poly(propylene). High-quality, high-resolution serial images were collected and the 3D structures were characterised quantitatively. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  6. Silver Streaks on Surface of Injected Thermoplastic Parts

    NASA Astrophysics Data System (ADS)

    Bílik, Jozef; Náplava, Antonín; Kusý, Martin; Košík, Miroslav; Likavčan, Lukáš

    2014-06-01

    Silver streaks on injected thermoplastic parts are the undesirable features, considered as a visual surface defect. If they appear, elimination of this technological problem can be very difficult, especially in case the cause of their occurrence is not actually known. In this study, the detailed analysis of silver streaks formation was carried out. At first, the defect was microscopically studied. Then, the several analyses were performed to find the cause of silver streaks formation. Finally, solutions to the problem and elimination and this kind of surface defect were suggested.

  7. Temperature-dependent dielectric properties of a thermoplastic gelatin

    NASA Astrophysics Data System (ADS)

    Landi, Giovanni; Neitzert, Heinz C.; Sorrentino, Andrea

    2016-05-01

    The frequency and the temperature dependence of the dielectric properties of a thermoplastic gelatin based bio-material have been investigated. At lower frequencies the dielectric response is strongly affected by charge carrier accumulation at the electrodes which modifies the dominating hopping conduction mechanism. The variation of the ac conductivity with frequency obeys a Jonscher type power law except for a small deviation in the low frequency range due to the electrode polarization effect. The master curve of the ac conductivity data shows that the conductivity relaxation of the gelatin is temperature independent.

  8. Induction Consolidation of Thermoplastic Composites Using Smart Susceptors

    SciTech Connect

    Matsen, Marc R

    2012-06-14

    This project has focused on the area of energy efficient consolidation and molding of fiber reinforced thermoplastic composite components as an energy efficient alternative to the conventional processing methods such as autoclave processing. The expanding application of composite materials in wind energy, automotive, and aerospace provides an attractive energy efficiency target for process development. The intent is to have this efficient processing along with the recyclable thermoplastic materials ready for large scale application before these high production volume levels are reached. Therefore, the process can be implemented in a timely manner to realize the maximum economic, energy, and environmental efficiencies. Under this project an increased understanding of the use of induction heating with smart susceptors applied to consolidation of thermoplastic has been achieved. This was done by the establishment of processing equipment and tooling and the subsequent demonstration of this fabrication technology by consolidating/molding of entry level components for each of the participating industrial segments, wind energy, aerospace, and automotive. This understanding adds to the nation's capability to affordably manufacture high quality lightweight high performance components from advanced recyclable composite materials in a lean and energy efficient manner. The use of induction heating with smart susceptors is a precisely controlled low energy method for the consolidation and molding of thermoplastic composites. The smart susceptor provides intrinsic thermal control based on the interaction with the magnetic field from the induction coil thereby producing highly repeatable processing. The low energy usage is enabled by the fact that only the smart susceptor surface of the tool is heated, not the entire tool. Therefore much less mass is heated resulting in significantly less required energy to consolidate/mold the desired composite components. This energy efficiency

  9. Computational modelling of a thermoforming process for thermoplastic starch

    NASA Astrophysics Data System (ADS)

    Szegda, D.; Song, J.; Warby, M. K.; Whiteman, J. R.

    2007-05-01

    Plastic packaging waste currently forms a significant part of municipal solid waste and as such is causing increasing environmental concerns. Such packaging is largely non-biodegradable and is particularly difficult to recycle or to reuse due to its complex composition. Apart from limited recycling of some easily identifiable packaging wastes, such as bottles, most packaging waste ends up in landfill sites. In recent years, in an attempt to address this problem in the case of plastic packaging, the development of packaging materials from renewable plant resources has received increasing attention and a wide range of bioplastic materials based on starch are now available. Environmentally these bioplastic materials also reduce reliance on oil resources and have the advantage that they are biodegradable and can be composted upon disposal to reduce the environmental impact. Many food packaging containers are produced by thermoforming processes in which thin sheets are inflated under pressure into moulds to produce the required thin wall structures. Hitherto these thin sheets have almost exclusively been made of oil-based polymers and it is for these that computational models of thermoforming processes have been developed. Recently, in the context of bioplastics, commercial thermoplastic starch sheet materials have been developed. The behaviour of such materials is influenced both by temperature and, because of the inherent hydrophilic characteristics of the materials, by moisture content. Both of these aspects affect the behaviour of bioplastic sheets during the thermoforming process. This paper describes experimental work and work on the computational modelling of thermoforming processes for thermoplastic starch sheets in an attempt to address the combined effects of temperature and moisture content. After a discussion of the background of packaging and biomaterials, a mathematical model for the deformation of a membrane into a mould is presented, together with its

  10. Fused Deposition Technique for Continuous Fiber Reinforced Thermoplastic

    NASA Astrophysics Data System (ADS)

    Bettini, Paolo; Alitta, Gianluca; Sala, Giuseppe; Di Landro, Luca

    2017-02-01

    A simple technique for the production of continuous fiber reinforced thermoplastic by fused deposition modeling, which involves a common 3D printer with quite limited modifications, is presented. An adequate setting of processing parameters and deposition path allows to obtain components with well-enhanced mechanical characteristics compared to conventional 3D printed items. The most relevant problems related to the simultaneous feeding of fibers and polymer are discussed. The properties of obtained aramid fiber reinforced polylactic acid (PLA) in terms of impregnation quality and of mechanical response are measured.

  11. Fused Deposition Technique for Continuous Fiber Reinforced Thermoplastic

    NASA Astrophysics Data System (ADS)

    Bettini, Paolo; Alitta, Gianluca; Sala, Giuseppe; Di Landro, Luca

    2016-12-01

    A simple technique for the production of continuous fiber reinforced thermoplastic by fused deposition modeling, which involves a common 3D printer with quite limited modifications, is presented. An adequate setting of processing parameters and deposition path allows to obtain components with well-enhanced mechanical characteristics compared to conventional 3D printed items. The most relevant problems related to the simultaneous feeding of fibers and polymer are discussed. The properties of obtained aramid fiber reinforced polylactic acid (PLA) in terms of impregnation quality and of mechanical response are measured.

  12. Nonlinear mechanical behavior of thermoplastic matrix materials for advanced composites

    NASA Technical Reports Server (NTRS)

    Arenz, R. J.; Landel, R. F.

    1989-01-01

    Two recent theories of nonlinear mechanical response are quantitatively compared and related to experimental data. Computer techniques are formulated to handle the numerical integration and iterative procedures needed to solve the associated sets of coupled nonlinear differential equations. Problems encountered during these formulations are discussed and some open questions described. Bearing in mind these cautions, the consequences of changing parameters that appear in the formulations on the resulting engineering properties are discussed. Hence, engineering approaches to the analysis of thermoplastic matrix material can be suggested.

  13. Heat flow analysis in connection with thermoplastic filament winding

    NASA Astrophysics Data System (ADS)

    Brage, Anders; Lamrell, Charles

    1988-04-01

    In thermoplastic filament winding the calculated rate of cooling is found to be in the order of 100000 degr.C/second at the bonding interface. Short range heat flow phenomena are analyzed, and the result provides a simple rule of thumb for practice, together with a winding speed dependant correction for glass and carbon fiber composites. This enables an easy method to calculate the lower temperature limits for the process of continuous welding, as well as the upper temperature limit where resin starved laminates result from excessive resin flow due to heat buildup. The applied model of heat transfer is given in analytical expressions. Calculated results are given in several graphs.

  14. Use of Vacuum Bagging for Fabricating Thermoplastic Microfluidic Devices

    PubMed Central

    Cassano, Christopher L.; Simon, Andrew J.; Liu, Wei; Fredrickson, Carl; Fan, Z. Hugh

    2014-01-01

    In this work we present a novel thermal bonding method for thermoplastic microfluidic devices. This simple method employs a modified vacuum bagging technique, a concept borrowed from the aerospace industry, to produce conventional thick substrate microfluidic devices, as well as multi-layer film devices. The bonds produced using this method are superior to those obtained using conventional thermal bonding methods, including thermal lamination, and are capable of sustaining burst pressures in excess of 550 kPa. To illustrate the utility of this method, thick substrate devices were produced, as well as a six-layer film device that incorporated several complex features. PMID:25329244

  15. Processing of thermoplastic matrix-carbon fiber composites

    SciTech Connect

    Adams, M.E.

    1992-01-01

    The effect of processing on the adhesion of AS-4 graphite fibers to polycarbonate, polyetherimide and polyester is examined. The adhesion is quantified using single fiber composite specimens. The specimens are carefully fabricated with different levels of applied pressure and cooling rate. It is found experimentally that both pressure and cooling rate can affect adhesion of the graphite fibers to the thermoplastic matrix materials. In general, adhesion is improved with higher pressures and slower cooling rates. Residual stress in a model composite is calculated and compared to the differences in adhesion with different processing histories. The results of the theory agree qualitatively with the experimental results.

  16. Laser Processing of Thermoplastic Composites for Wound Solid Rocket Boosters

    NASA Astrophysics Data System (ADS)

    Krzeminski, M.; Jaguenaud, L.; Defoort, B.; Briant, P.

    2014-06-01

    Airbus Defence and space is currently developing laser- assisted winding of thermoplastic based composites with in-situ consolidation as well as automated fiber placement of the same materials. The objective is to be able to manufacture large scale out-of-autoclave motor cases for future launchers application with reduced costs, high productivity and reliability and taking into account environmental concerns and regulations. The paper presents the developments that have been carried out on materials and process and presents the manufacturing of various different demonstrators.

  17. Biodegradation of thermoplastic starch/eggshell powder composites.

    PubMed

    Bootklad, Munlika; Kaewtatip, Kaewta

    2013-09-12

    Thermoplastic starch (TPS) was prepared using compression molding and chicken eggshell was used as a filler. The effect of the eggshell powder (EP) on the properties of TPS was compared with the effect of commercial calcium carbonate (CC). The organic compound on the surface of the eggshell powder acted as a coupling agent that resulted in a strong adhesion between the eggshell powder and the TPS matrix, as confirmed by SEM micrographs. The biodegradation was determined by the soil burial test. The TPS/EP composites were more rapidly degraded than the TPS/CC composites. In addition, the eggshell powder improved the water resistance and thermal stability of the TPS.

  18. FIBER ORIENTATION IN INJECTION MOLDED LONG CARBON FIBER THERMOPLASTIC COMPOSITES

    SciTech Connect

    Wang, Jin; Nguyen, Ba Nghiep; Mathur, Raj N.; Sharma, Bhisham; Sangid, Michael D.; Costa, Franco; Jin, Xiaoshi; Tucker III, Charles L.; Fifield, Leonard S.

    2015-03-23

    A set of edge-gated and center-gated plaques were injection molded with long carbon fiber-reinforced thermoplastic composites, and the fiber orientation was measured at different locations of the plaques. Autodesk Simulation Moldflow Insight (ASMI) software was used to simulate the injection molding of these plaques and to predict the fiber orientation, using the anisotropic rotary diffusion and the reduced strain closure models. The phenomenological parameters of the orientation models were carefully identified by fitting to the measured orientation data. The fiber orientation predictions show very good agreement with the experimental data.

  19. Use of vacuum bagging for fabricating thermoplastic microfluidic devices.

    PubMed

    Cassano, Christopher L; Simon, Andrew J; Liu, Wei; Fredrickson, Carl; Fan, Z Hugh

    2015-01-07

    In this work we present a novel thermal bonding method for thermoplastic microfluidic devices. This simple method employs a modified vacuum bagging technique, a concept borrowed from the aerospace industry, to produce conventional thick substrate microfluidic devices, as well as multi-layer film devices. The bonds produced using this method are superior to those obtained using conventional thermal bonding methods, including thermal lamination, and are capable of sustaining burst pressures in excess of 550 kPa. To illustrate the utility of this method, thick substrate devices were produced, as well as a six-layer film device that incorporated several complex features.

  20. Multicomponent Solvated Triblock Copolymer Network Systems: Fundamental Insights and Emerging Applications

    NASA Astrophysics Data System (ADS)

    Krishnan, Arjun Sitaraman

    Block copolymers have received significant research attention in recent times due to their ability to spontaneously self-assemble into a variety of nanostructures. Thermoplastic elastomers composed of styrenic triblock copolymers are of great importance in applications such as adhesives and vibration dampening due to their shape memory, resilience and facile processing. The swelling of these polymers by adding midblock selective solvents or oligomers provides an easy route by which to modify the morphology and mechanical behavior of these systems. We first consider a ternary blend of a poly[styrene- b-(ethylene-co-butylene)-b-styrene] triblock copolymer (SEBS) and mixtures of two midblock selective co-solvents, with significantly different physical states. We use dynamic rheology to study the viscoelastic response of a wide variety of systems under oscillatory shear. Frequency spectra acquired at ambient temperature display viscoelastic behavior that shifts in the frequency domain depending on the co-solvent composition. For each copolymer concentration, all the frequency data can be shifted by time-composition superpositioning (tCS) to yield a single master-curve. tCS fails at low frequencies due to presence of endblock pullout, which is a fundamentally different relaxation process from segmental relaxation of the midblock. As an emerging technology, we examine SEBS-oil gels as dielectric elastomers. Dielectric elastomers constitute one class of electroactive polymers (EAPs), polymeric materials that respond to an electric stimulus by changing their macroscopic dimensions, thereby converting electrical energy into mechanical work. We use standard configuration of EAP devices involving stretching, or "prestraining," the elastomer film biaxially. The effect of experimental parameters such as film thickness and amount of prestrain on the (electro)mechanical properties of the material become apparent by recasting as-obtained electroactuation data into compressive

  1. Triblock copolymers based on ε-caprolactone and trimethylene carbonate for the 3D printing of tissue engineering scaffolds.

    PubMed

    Güney, Aysun; Malda, Jos; Dhert, Wouter J A; Grijpma, Dirk W

    2017-05-09

    Biodegradable PCL-b-PTMC-b-PCL triblock copolymers based on trimethylene carbonate (TMC) and ε-caprolactone (CL) were prepared and used in the 3D printing of tissue engineering scaffolds. Triblock copolymers of various molecular weights containing equal amounts of TMC and CL were prepared. These block copolymers combine the low glass transition temperature of amorphous PTMC (approximately -20°C) and the semi-crystallinity of PCL (glass transition approximately -60°C and melting temperature approximately 60°C). PCL-b-PTMC-b-PCL triblock copolymers were synthesized by sequential ring opening polymerization (ROP) of TMC and ε-CL. From these materials, films were prepared by solvent casting and porous structures were prepared by extrusion-based 3D printing. Films prepared from a polymer with a relatively high molecular weight of 62 kg/mol had a melting temperature of 58°C and showed tough and resilient behavior, with values of the elastic modulus, tensile strength and elongation at break of approximately 120 MPa, 16 MPa and 620%, respectively. Porous structures were prepared by 3D printing. Ethylene carbonate was used as a crystalizable and water-extractable solvent to prepare structures with microporous strands. Solutions, containing 25 wt% of the triblock copolymer, were extruded at 50°C then cooled at different temperatures. Slow cooling at room temperature resulted in pores with widths of 18 ± 6 μm and lengths of 221 ± 77 μm, rapid cooling with dry ice resulted in pores with widths of 13 ± 3 μm and lengths of 58 ± 12 μm. These PCL-b-PTMC-b-PCL triblock copolymers processed into porous structures at relatively low temperatures may find wide application as designed degradable tissue engineering scaffolds. In this preliminary study we prepared biodegradable triblock copolymers based on 1,3-trimethylene carbonate and ε-caprolactone and assessed their physical characteristics. Furthermore, we evaluated their potential as melt-processable thermoplastic

  2. Responsive copolymers for enhanced petroleum recovery

    SciTech Connect

    McCormick, C.; Hester, R.

    1992-01-01

    The overall goal of this research is the development of advanced water-soluble copolymers for use in enhanced oil recovery which rely on reversible microheterogeneous associations for mobility control and reservoir conformance. Technical progress is summarized for the following tasks: advanced copolymer synthesis; characterization of macromolecular structure and properties; and solution rheology in a porous media.

  3. Thermochemical characteristics of chitosan-polylactide copolymers

    NASA Astrophysics Data System (ADS)

    Goruynova, P. E.; Larina, V. N.; Smirnova, N. N.; Tsverova, N. E.; Smirnova, L. A.

    2016-05-01

    The energies of combustion of chitosan and its block-copolymers with different polylactide contents are determined in a static bomb calorimeter. Standard enthalpies of combustion and formation are calculated for these substances. The dependences of the thermochemical characteristics on block-copolymer composition are determined and discussed.

  4. Dimensionally Stable Ether-Containing Polyimide Copolymers

    NASA Technical Reports Server (NTRS)

    Fay, Catharine C. (Inventor); St.Clair, Anne K. (Inventor)

    1999-01-01

    Novel polyimide copolymers containing ether linkages were prepared by the reaction of an equimolar amount of dianhydride and a combination of diamines. The polyimide copolymers described herein possess the unique features of low moisture uptake, dimensional stability, good mechanical properties, and moderate glass transition temperatures. These materials have potential application as encapsulants and interlayer dielectrics.

  5. Process-Accessible States of Block Copolymers

    NASA Astrophysics Data System (ADS)

    Sun, De-Wen; Müller, Marcus

    2017-02-01

    Process-directed self-assembly of block copolymers refers to thermodynamic processes that reproducibly direct the kinetics of structure formation from a starting, unstable state into a selected, metastable mesostructure. We investigate the kinetics of self-assembly of linear A C B triblock copolymers after a rapid transformation of the middle C block from B to A . This prototypical process (e.g., photochemical transformation) converts the initial, equilibrium mesophase of the A B B copolymer into a well-defined but unstable, starting state of the A A B copolymer. The spontaneous structure formation that ensues from this unstable state becomes trapped in a metastable mesostructure, and we systematically explore which metastable mesostructures can be fabricated by varying the block copolymer composition of the initial and final states. In addition to the equilibrium mesophases of linear A B diblock copolymers, this diagram of process-accessible states includes 7 metastable periodic mesostructures, inter alia, Schoen's F-RD periodic minimal surface. Generally, we observe that the final, metastable mesostructure of the A A B copolymer possesses the same symmetry as the initial, equilibrium mesophase of the A B B copolymer.

  6. Nanostructured high-performance dielectric block copolymers.

    PubMed

    Liu, Wenmei; Liao, Xiaojuan; Li, Yawei; Zhao, Qiuhua; Xie, Meiran; Sun, Ruyi

    2015-10-25

    A new type of insulating-conductive block copolymer was synthesized by metathesis polymerization. The copolymer can self-assemble into unique nanostructures of micelles or hollow spheres. It exhibits a high dielectric constant, low dielectric loss, and high stored/released energy density due to the strong dipolar and nano-interfacial polarization contributions.

  7. Process-Accessible States of Block Copolymers.

    PubMed

    Sun, De-Wen; Müller, Marcus

    2017-02-10

    Process-directed self-assembly of block copolymers refers to thermodynamic processes that reproducibly direct the kinetics of structure formation from a starting, unstable state into a selected, metastable mesostructure. We investigate the kinetics of self-assembly of linear ACB triblock copolymers after a rapid transformation of the middle C block from B to A. This prototypical process (e.g., photochemical transformation) converts the initial, equilibrium mesophase of the ABB copolymer into a well-defined but unstable, starting state of the AAB copolymer. The spontaneous structure formation that ensues from this unstable state becomes trapped in a metastable mesostructure, and we systematically explore which metastable mesostructures can be fabricated by varying the block copolymer composition of the initial and final states. In addition to the equilibrium mesophases of linear AB diblock copolymers, this diagram of process-accessible states includes 7 metastable periodic mesostructures, inter alia, Schoen's F-RD periodic minimal surface. Generally, we observe that the final, metastable mesostructure of the AAB copolymer possesses the same symmetry as the initial, equilibrium mesophase of the ABB copolymer.

  8. Synthesis and Characterization of Block Copolymers.

    DTIC Science & Technology

    1987-07-01

    Polyether-Polyimide Block Copolymers; Three series of Polyether-Polyimide (PEPI) block copolymers were synthesized. Soft segments were poly( propylene ... glycol ) (PPO) Mn = 2,000 and 4,000. Hard segments were pyromellitic dianhydride (PMDA) and di-(2-hydroxyethyl)-dimethylhydantoin (H). The hard

  9. Imide/arylene ether block copolymers

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Two series of imide/arylene either block copolymers were prepared using an arylene ether block and either an amorphous or semi-crystalline imide block. The resulting copolymers were characterized and selected physical and mechanical properties were determined. These results, as well as comparisons to the homopolymer properties, are discussed.

  10. Magnetostrictive pressure device for thermoplastic fiber placement process

    NASA Astrophysics Data System (ADS)

    Ahrens, Markus; Mallick, Vishal

    1999-07-01

    Fiber reinforced composites offer excellent specific stiffness and strength and are therefore interesting for rotating machinery applications. The main disadvantage of high performance composites is the manufacturing process which is labor intensive and thus slow and expensive. The Thermoplastic Fiber Placement process overcomes these difficulties due to its high degree of automation. During the process, an impregnated tape is heated up and then consolidated in-situ under pressure. The process which is used at ABB consists of a six axis robot, a heat source and a pressure device for consolidation. Today mechanical roller element are used to apply the forces normal to the surface to the composite part. These forces are necessary for proper consolidation. The roller action prevents damage due to shearing of the tape during lay down. To improve the processing sped, and to expand the use of the Thermoplastic Fiber Placement process for more complex structures, two severe drawbacks of the solid roller approach need to be overcome; the small pressure contact area which limits the speed of the process and the poor conformability which prevents the process from being applied to highly 3D surfaces. Smart materials such as piezoelectrics, electrostrictives and magnetostrictives can produce high forces at high operating frequencies and enable a large, conformable actuated surface to be realized. A pressure device made with a magnetostrictive actuator has been tested. The main design goal is to apply the consolidation pressure correctly, without introducing shear forces on the tape, in order to produce parts with optimal mechanical properties.

  11. Interlaminate Deformation in Thermoplastic Composite Laminates: Experimental-Numerical Correlation

    NASA Astrophysics Data System (ADS)

    Shen, M.; Tong, J.; Wang, S.; Fang, Y.

    2010-06-01

    The interlaminar deformation behaviors of thermoplastic AS4/PEEK composite laminates subjected to static tensile loading are investigated by means of microscopic moiré interferometry with high spatial resolution. The fully threedimensional orthotropic elastic-plastic analysis of interlaminar deformation for the thermoplastic laminates is developed in this paper, and used to simulate the stress-strain curves of tensile experiment for its angle-ply laminates. Under uniaxial tensile loading, the 3D orthotropic elastic-plastic FE analysis and microscopic moiré interferometry of interlaminar deformations are carried out for the [±25]S4 laminates. The quantitative local-filed experimental results of interlaminar shear strain and displacements at freeedge surface of the laminate are compared with corresponding numerical results of the orthotropic elastic-plastic FE model. It is indicated that the numerical tensile stressstrain curves of angle-ply laminates computed with 3D orthotropic elastic-plastic model are agree with experimental results. The numerical interlaminar displacement U and shear strain γxz are also consistent with the experimental results obtained by moiré interferometry. It is expected the elastic-plastic interlaminar stresses and deformations analysis for the optimal design and application of AS4/PEEK laminates and its structures.

  12. Stress-induced structural changes in thermoplastic composites

    SciTech Connect

    Kitano, A.

    1991-01-01

    Polymeric Composites: Cyclic stress effects on PEEK (Poly-ether-ether-ketone) matrix thermoplastic composite system were examined by thermal-analysis techniques: DSC (Differential Scanning Calorimeter), DMA (Dynamic Mechanical Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), DGT (Density Gradient Technique), and WAXS (Wide angle X-ray Scattering). These measurements identified for the first time stress-induced crystallization of PEEK below the glass transition temperature (Tg). Also, PEEK crystallization above T[sub g] was kinetically studied by DSC and DMA, and a previously developed dual-crystallization methodology was extended to account for the influence of stress on crystallization. Finally, a fatigue kinetic model for un-notched PEEK films and a crack propagation model for PEEK composites were also developed providing a relation between matrix morphology and end-use performance. Collectively, this work established the importance of structural changes in thermoplastic-based composites that can be both monitored and influenced by dynamic (cyclic) mechanical experiments.

  13. 3D thermoplastic elastomer microfluidic devices for biological probe immobilization.

    PubMed

    Brassard, Daniel; Clime, Liviu; Li, Kebin; Geissler, Matthias; Miville-Godin, Caroline; Roy, Emmanuel; Veres, Teodor

    2011-12-07

    Microfluidics has emerged as a valuable tool for the high-resolution patterning of biological probes on solid supports. Yet, its widespread adoption as a universal biological immobilization tool is still limited by several technical challenges, particularly for the patterning of isolated spots using three-dimensional (3D) channel networks. A key limitation arises from the difficulties to adapt the techniques and materials typically used in prototyping to low-cost mass-production. In this paper, we present the fabrication of thin thermoplastic elastomer membranes with microscopic through-holes using a hot-embossing process that is compatible with high-throughput manufacturing. The membranes provide the basis for the fabrication of highly integrated 3D microfluidic devices with a footprint of only 1 × 1 cm(2). When placed on a solid support, the device allows for the immobilization of up to 96 different probes in the form of a 10 × 10 array comprising isolated spots of 50 × 50 μm(2). The design of the channel network is optimized using 3D simulations based on the Lattice-Boltzmann method to promote capillary action as the sole force distributing the liquid in the device. Finally, we demonstrate the patterning of DNA and protein arrays on hard thermoplastic substrates yielding spots of excellent definition that prove to be highly specific in subsequent hybridization experiments.

  14. The analysis of thermoplastic characteristics of special polymer sulfur composite

    NASA Astrophysics Data System (ADS)

    Książek, Mariusz

    2017-01-01

    Specific chemical environments step out in the industry objects. Portland cement composites (concrete and mortar) were impregnated by using the special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot was applied as the industrial waste. Portland cement composites were made of the same aggregate, cement and water. The process of special polymer sulfur composite applied as the industrial waste is a thermal treatment process in the temperature of about 150-155°C. The result of such treatment is special polymer sulfur composite in a liquid state. This paper presents the plastic constants and coefficients of thermal expansion of special polymer sulfur composites, with isotropic porous matrix, reinforced by disoriented ellipsoidal inclusions with orthotropic symmetry of the thermoplastic properties. The investigations are based on the stochastic differential equations of solid mechanics. A model and algorithm for calculating the effective characteristics of special polymer sulfur composites are suggested. The effective thermoplastic characteristics of special polymer sulfur composites, with disoriented ellipsoidal inclusions, are calculated in two stages: First, the properties of materials with oriented inclusions are determined, and then effective constants of a composite with disoriented inclusions are determined on the basis of the Voigt or Rice scheme. A brief summary of new products related to special polymer sulfur composites is given as follows: Impregnation, repair, overlays and precast polymer concrete will be presented. Special polymer sulfur as polymer coating impregnation, which has received little attention in recent years, currently has some very interesting applications.

  15. Injection Molding of Flat Glass Fiber Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuto; Katayama, Tsutao; Tanaka, Tatsuya; Anguri, Akihiro

    During an injection molding of composite materials, fiber attrition occurs and the average fiber length is reduced. In order to control the breakage of fibers and degradation of mechanical properties during processing, Flat glass Fiber (FF), that has oval cross-section shape, has been developed to use for glass fiber reinforced thermoplastic (GFRTP). Using FF as reinforcement of GFRTP has advantages as following: (1) Fluidity of FF is better than conventional Normal glass Fiber (NF) with 'circular' cross-section; (2) Fiber breakage during the injection molding process using FF is smaller than that using NF. In this study, the mechanical properties of FF and NF were compared for reinforcement of long fiber thermoplastics pellets (LFT pellets). We have also investigated the effect of screw design on fiber damage and the mechanical properties. The mechanical properties of specimens molded by FF reinforcement LFT (FF-LFT) pellets were superior to these of NF reinforcement LFT (NF-LFT) pellets. The former could give composites with higher fluidity and longer residual fiber length. Moreover, FF was able to strengthen injection-molded samples with higher fiber content than NF. Low shear type screw was effective to prevent the fiber attrition during plasticization process, hence leads to better mechanical properties of GFRTP

  16. Thermoplastic processing of proteins for film formation--a review.

    PubMed

    Hernandez-Izquierdo, V M; Krochta, J M

    2008-03-01

    Increasing interest in high-quality food products with increased shelf life and reduced environmental impact has encouraged the study and development of edible and/or biodegradable polymer films and coatings. Edible films provide the opportunity to effectively control mass transfer among different components in a food or between the food and its surrounding environment. The diversity of proteins that results from an almost limitless number of side-chain amino-acid sequential arrangements allows for a wide range of interactions and chemical reactions to take place as proteins denature and cross-link during heat processing. Proteins such as wheat gluten, corn zein, soy protein, myofibrillar proteins, and whey proteins have been successfully formed into films using thermoplastic processes such as compression molding and extrusion. Thermoplastic processing can result in a highly efficient manufacturing method with commercial potential for large-scale production of edible films due to the low moisture levels, high temperatures, and short times used. Addition of water, glycerol, sorbitol, sucrose, and other plasticizers allows the proteins to undergo the glass transition and facilitates deformation and processability without thermal degradation. Target film variables, important in predicting biopackage performance under various conditions, include mechanical, thermal, barrier, and microstructural properties. Comparisons of film properties should be made with care since results depend on parameters such as film-forming materials, film formulation, fabrication method, operating conditions, testing equipment, and testing conditions. Film applications include their use as wraps, pouches, bags, casings, and sachets to protect foods, reduce waste, and improve package recyclability.

  17. Extrusion foaming of protein-based thermoplastic and polyethylene blends

    NASA Astrophysics Data System (ADS)

    Gavin, Chanelle; Lay, Mark C.; Verbeek, Casparus J. R.

    2016-03-01

    Currently the extrusion foamability of Novatein® Thermoplastic Protein (NTP) is being investigated at the University of Waikato in collaboration with the Biopolymer Network Ltd (NZ). NTP has been developed from bloodmeal (>86 wt% protein), a co-product of the meat industry, by adding denaturants and plasticisers (tri-ethylene glycol and water) allowing it to be extruded and injection moulded. NTP alone does not readily foam when sodium bicarbonate is used as a chemical blowing agent as its extensional viscosity is too high. The thermoplastic properties of NTP were modified by blending it with different weight fractions of linear low density polyethylene (LLDPE) and polyethylene grafted maleic anhydride (PE-g-MAH) compatibiliser. Extrusion foaming was conducted in two ways, firstly using the existing water content in the material as the blowing agent and secondly by adding sodium bicarbonate. When processed in a twin screw extruder (L/D 25 and 10 mm die) the material readily expanded due to the internal moisture content alone, with a conditioned expansion ratio of up to ± 0.13. Cell structure was non-uniform exhibiting a broad range cell sizes at various stages of formation with some coalescence. The cell size reduced through the addition of sodium bicarbonate, overall more cells were observed and the structure was more uniform, however ruptured cells were also visible on the extrudate skin. Increasing die temperature and introducing water cooling reduced cell size, but the increased die temperature resulted in surface degradation.

  18. CREEP MODELING FOR INJECTION-MOLDED LONG-FIBER THERMOPLASTICS

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

    2008-06-30

    This paper proposes a model to predict the creep response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the nonlinear viscoelastic behavior described by the Schapery’s model. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber length and orientation distributions were measured and used in the analysis that applies the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption (termed as the Eshelby-Mori-Tanaka approach) and the fiber orientation averaging technique to compute the overall strain increment resulting from an overall constant applied stress during a given time increment. The creep model for LFTs has been implemented in the ABAQUS finite element code via user-subroutines and has been validated against the experimental creep data obtained for long-glass-fiber/polypropylene specimens. The effects of fiber orientation and length distributions on the composite creep response are determined and discussed.

  19. Processible Polyaniline Copolymers and Complexes.

    NASA Astrophysics Data System (ADS)

    Liao, Yun-Hsin

    1995-01-01

    Polyaniline (PANI) is an intractable polymer due to the difficulty of melt processing or dissolving it in common solvents. The purpose of the present investigation was to prepare a new class of conducting polyanilines with better solubility both in base and dope forms by (1) adding external salt to break aggregated chains, (2) introducing ring substituted units onto the backbone without disturbing the coplanar structure, and (3) complexing with polymeric dopants to form a soluble polymer complex. Aggregation of PANI chains in dilute solution was investigated in N-methyl-2-pyrrolidinone (NMP) by light scattering, gel permeation chromatography, and viscosity measurements. The aggregation of chains resulted in a negative second virial coefficient in light scattering measurement, a bimodal molecular weight distribution in gel permeation chromatography, and concave reduced viscosity curves. The aggregates can be broken by adding external salt, which resulting in a higher reduced viscosity. The driving force for aggregation is assumed to be a combination of hydrogen bonding between the imine and amine groups, and the rigidity of backbone. The aggregation was modeled to occur via side-on packing of PANI chains. The ring substituted PANI copolymers, poly(aniline -co-phenetidine) were synthesized by chemical oxidation copolymerization using ammonium persulfate as an oxidant. The degree of copolymerization declined with an increasing feed of o-phenetidine in the reaction mixture. The o-phenetidine had a higher reactivity than aniline in copolymerization resulting in a higher content of o-phenetidine in copolymers. The resulting copolymers can be readily dissolved in NMP up to 20% (w/w), and other common solvents, and solutions possess a longer gelation time. The highly soluble copolymer with 20 mole % o-phenetidine in the backbone has same order of conductivity as the unsubstituted PANI after it is doped by HCl. Complexation of PANI and polymeric dopant, poly

  20. Hybridization of Block Copolymer Micelles

    DTIC Science & Technology

    1993-01-01

    J. Macromol. Sci., Part A 1973, 7,601. (10) Tiara, M.; Ramireddy, C.; Webber, S. K; Munk,P. Collect. Czer" (14) 0snford, C. In The Hydrophobic Effect ...equilibrate In the first series of experiments we have studied the within 20 min, similarly as ASA-10 micelles do. However, effect of the copolymer...high. This may happen after a sudden The Johnston-Ogston effect 2’ 6- also may play a role in jump in temperature or in the composition of the mixed

  1. Dielectric characterization of PCL-based thermoplastic materials for microwave diagnostic and therapeutic applications.

    PubMed

    Aguilar, Suzette M; Shea, Jacob D; Al-Joumayly, Mudar A; Van Veen, Barry D; Behdad, Nader; Hagness, Susan C

    2012-03-01

    We propose the use of a polycaprolactone (PCL)-based thermoplastic mesh as a tissue-immobilization interface for microwave imaging and microwave hyperthermia treatment. An investigation of the dielectric properties of two PCL-based thermoplastic materials in the frequency range of 0.5-3.5 GHz is presented. The frequency-dependent dielectric constant and effective conductivity of the PCL-based thermoplastics are characterized using measurements of microstrip transmission lines fabricated on substrates comprised of the thermoplastic meshes. We also examine the impact of the presence of a PCL-based thermoplastic mesh on microwave breast imaging. We use a numerical test bed comprised of a previously reported 3-D anatomically realistic breast phantom and a multi-frequency microwave inverse scattering algorithm. We demonstrate that the PCL-based thermoplastic material and the assumed biocompatible medium of vegetable oil are sufficiently well matched such that the PCL layer may be neglected by the imaging solution without sacrificing imaging quality. Our results suggest that PCL-based thermoplastics are promising materials as tissue immobilization structures for microwave diagnostic and therapeutic applications.

  2. Dielectric Characterization of PCL-Based Thermoplastic Materials for Microwave Diagnostic and Therapeutic Applications

    PubMed Central

    Aguilar, Suzette M.; Shea, Jacob D.; Al-Joumayly, Mudar A.; Van Veen, Barry D.; Behdad, Nader; Hagness, Susan C.

    2011-01-01

    We propose the use of a polycaprolactone (PCL)-based thermoplastic mesh as a tissue-immobilization interface for microwave imaging and microwave hyperthermia treatment. An investigation of the dielectric properties of two PCL-based thermoplastic materials in the frequency range of 0.5 – 3.5 GHz is presented. The frequency-dependent dielectric constant and effective conductivity of the PCL-based thermoplastics are characterized using measurements of microstrip transmission lines fabricated on substrates comprised of the thermoplastic meshes. We also examine the impact of the presence of a PCL-based thermoplastic mesh on microwave breast imaging. We use a numerical test bed comprised of a previously reported three-dimensional anatomically realistic breast phantom and a multi-frequency microwave inverse scattering algorithm. We demonstrate that the PCL-based thermoplastic material and the assumed biocompatible medium of vegetable oil are sufficiently well matched such that the PCL layer may be neglected by the imaging solution without sacrificing imaging quality. Our results suggest that PCL-based thermoplastics are promising materials as tissue immobilization structures for microwave diagnostic and therapeutic applications. PMID:21622068

  3. Manufacturing of a REBCO racetrack coil using thermoplastic resin aiming at Maglev application

    NASA Astrophysics Data System (ADS)

    Mizuno, Katsutoshi; Ogata, Masafumi; Hasegawa, Hitoshi

    2015-11-01

    The REBCO coated conductor is a promising technology for the Maglev application in terms of its high critical temperature. The operating temperature of the on-board magnets can be around 40-50 K with the coated conductor. The REBCO coils are cooled by cryocoolers directly, and hence the thermal design of the REBCO coils significantly changes from that of LTS coils. We have developed a novel REBCO coil structure using thermoplastic resin. The coil is not impregnated and the thermoplastic resin is used to bond the coil winding and the heat transfer members, e.g. copper and aluminum plates. The viscosity of the thermoplastic resin is high enough for the thermoplastic resin not to permeate between the turns in the coil. Therefore, the thermal stress does not occur and the risk of degradation is removed. This paper contains the following three topics. First, the thermal resistance of the thermoplastic resin was measured at cryogenic temperature. Then, a small round REBCO coil was experimentally produced. It has been confirmed that the thermoplastic resin does not cause the degradation and, the adhesion between the coil winding and copper plates withstands the thermal stress. Finally, we successfully produced a full-scale racetrack REBCO coil applying the coil structure with the thermoplastic resin.

  4. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false n-Alkylglutarimide/acrylic copolymers. 177.1060... Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic...) Identity. For the purpose of this section, n-alkylglutarimide/acrylic copolymers are copolymers obtained by...

  5. Rapid self-assembly of block copolymers to photonic crystals

    DOEpatents

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

    2016-07-05

    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  6. Utilization of Network-Forming Block Copolymers and Ionomers in the Development of Novel Nanostructures and Responsive Media

    NASA Astrophysics Data System (ADS)

    Mineart, Kenneth

    Network forming block copolymers, i.e. thermoplastic elastomers (TPEs), are one of the highest commodity forms of block copolymers due to their competitive elasticity and extendability as well as their ability to be melt and solution processed. TPEs owe many of their advantages to a combination of hard and soft blocks. The soft blocks, which must be covalently bound at both ends to hard blocks, connect adjacent hard domains resulting in physically cross-linked systems. Herein, simulations and theory are used to provide a molecular-level depiction of the evolution from diblock copolymers, which do not contain the ability to form physical cross-links, to network forming triblock copolymers. In addition, systems with high interblock incompatibility that are within the diblock-to-triblock transition (i.e. having high molecular asymmetry) are identified to form three component (ABC triblock copolymer) phases from copolymer containing only two chemically distinct blocks. Following this work, which emphasizes the fundamental principle of TPEs, the dissertation shifts focus to physically- and chemically-modified triblock and pentablock copolymer TPEs. Recent progress has sought to broaden TPEs to include properties that are above and beyond their inherent mechanical benefits, including responsiveness to external stimuli. The first examples presented here consist of TPEs prepared in combination with amorphous hydrocarbon additives to yield TPE gels (TPEGs). The resulting TPEGs, which maintain the beneficial processing properties of TPEs, are subsequently molded into 1- and 2-D arrays of microchannels that are filled with liquid metal. The final devices exhibit strain-sensitive electrical conductivity to at least 600% strain, have tunable compliance (ease of stretching), and are fully recyclable. The substitution of the amorphous hydrocarbon component for crystalline analogues with melting points <100 °C yield TPE composites (TPECs). The TPECs gain the added capability of

  7. Sub-second thermoplastic forming of bulk metallic glasses by ultrasonic beating.

    PubMed

    Ma, Jiang; Liang, Xiong; Wu, Xiaoyu; Liu, Zhiyuan; Gong, Feng

    2015-12-08

    The work proposed a novel thermoplastic forming approach-the ultrasonic beating forming (UBF) method for bulk metallic glasses (BMGs) in present work. The rapid forming approach can finish the thermoplastic forming of BMGs in less than one second, avoiding the time-dependent crystallization and oxidation to the most extent. Besides, the UBF is also proved to be competent in the fabrication of structures with the length scale ranging from macro scale to nano scale. Our results propose a novel route for the thermoplastic forming of BMGs and have promising applications in the rapid fabrication of macro to nano scale products and devices.

  8. Sub-second thermoplastic forming of bulk metallic glasses by ultrasonic beating

    PubMed Central

    Ma, Jiang; Liang, Xiong; Wu, Xiaoyu; Liu, Zhiyuan; Gong, Feng

    2015-01-01

    The work proposed a novel thermoplastic forming approach–the ultrasonic beating forming (UBF) method for bulk metallic glasses (BMGs) in present work. The rapid forming approach can finish the thermoplastic forming of BMGs in less than one second, avoiding the time-dependent crystallization and oxidation to the most extent. Besides, the UBF is also proved to be competent in the fabrication of structures with the length scale ranging from macro scale to nano scale. Our results propose a novel route for the thermoplastic forming of BMGs and have promising applications in the rapid fabrication of macro to nano scale products and devices. PMID:26644149

  9. High performance thermoplastics: A review of neat resin and composite properties

    NASA Technical Reports Server (NTRS)

    Johnston, Norman J.; Hergenrother, Paul M.

    1987-01-01

    A review was made of the principal thermoplastics used to fabricate high performance composites. Neat resin tensile and fracture toughness properties, glass transition temperatures (Tg), crystalline melt temperatures (Tm) and approximate processing conditions are presented. Mechanical properties of carbon fiber composites made from many of these thermoplastics are given, including flexural, longitudinal tensile, transverse tensile and in-plane shear properties as well as short beam shear and compressive strengths and interlaminar fracture toughness. Attractive features and problems involved in the use of thermo-plastics as matrices for high performance composites are discussed.

  10. Analytical and experimental evaluation of techniques for the fabrication of thermoplastic hologram storage devices

    NASA Technical Reports Server (NTRS)

    Rogers, J. W.

    1975-01-01

    The results of an experimental investigation on recording information on thermoplastic are given. A description was given of a typical fabrication configuration, the recording sequence, and the samples which were examined. There are basically three configurations which can be used for the recording of information on thermoplastic. The most popular technique uses corona which furnishes free charge. The necessary energy for deformation is derived from a charge layer atop the thermoplastic. The other two techniques simply use a dc potential in place of the corona for deformation energy.

  11. Biodegradable polymer blends based on corn starch and thermoplastic chitosan processed by extrusion.

    PubMed

    Mendes, J F; Paschoalin, R T; Carmona, V B; Sena Neto, Alfredo R; Marques, A C P; Marconcini, J M; Mattoso, L H C; Medeiros, E S; Oliveira, J E

    2016-02-10

    Blends of thermoplastic cornstarch (TPS) and chitosan (TPC) were obtained by melt extrusion. The effect of TPC incorporation in TPS matrix and polymer interaction on morphology and thermal and mechanical properties were investigated. Possible interactions between the starch molecules and thermoplastic chitosan were assessed by XRD and FTIR techniques. Scanning Electron Microscopy (SEM) analyses showed a homogeneous fracture surface without the presence of starch granules or chitosan aggregates. Although the incorporation of thermoplastic chitosan caused a decrease in both tensile strength and stiffness, films with better extensibility and thermal stability were produced.

  12. Characterization of bonding between poly(dimethylsiloxane) and cyclic olefin copolymer using corona discharge induced grafting polymerization.

    PubMed

    Liu, Ke; Gu, Pan; Hamaker, Kiri; Fan, Z Hugh

    2012-01-01

    Thermoplastics have been increasingly used for fabricating microfluidic devices because of their low cost, mechanical/biocompatible attributes, and well-established manufacturing processes. However, there is sometimes a need to integrate such a device with components made from other materials such as polydimethylsiloxane (PDMS). Bonding thermoplastics with PDMS to produce hybrid devices is not straightforward. We have reported our method to modify the surface property of a cyclic olefin copolymer (COC) substrate by using corona discharge and grafting polymerization of 3-(trimethoxysilyl)propyl methacrylate; the modified surface enabled strong bonding of COC with PDMS. In this paper, we report our studies on the surface modification mechanism using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurement. Using this bonding method, we fabricated a three-layer (COC/PDMS/COC) hybrid device consisting of elastomer-based valve arrays. The microvalve operation was confirmed through the displacement of a dye solution in a fluidic channel when the elastomer membrane was pneumatically actuated. Valve-enabled microfluidic handling was demonstrated.

  13. Microphase separation in random multiblock copolymers

    NASA Astrophysics Data System (ADS)

    Govorun, E. N.; Chertovich, A. V.

    2017-01-01

    Microphase separation in random multiblock copolymers is studied with the mean-field theory assuming that long blocks of a copolymer are strongly segregated, whereas short blocks are able to penetrate into "alien" domains and exchange between the domains and interfacial layer. A bidisperse copolymer with blocks of only two sizes (long and short) is considered as a model of multiblock copolymers with high polydispersity in the block size. Short blocks of the copolymer play an important role in the microphase separation. First, their penetration into the "alien" domains leads to the formation of joint long blocks in their own domains. Second, short blocks localized at the interface considerably change the interfacial tension. The possibility of penetration of short blocks into the "alien" domains is controlled by the product χ Nsh (χ is the Flory-Huggins interaction parameter and Nsh is the short block length). At not very large χ Nsh , the domain size is larger than that for a regular copolymer consisting of the same long blocks as in the considered random copolymer. At a fixed mean block size, the domain size grows with an increase in the block size dispersity, the rate of the growth being dependent of the more detailed parameters of the block size distribution.

  14. Synthesis and characterization of aryl phosphine oxide containing thermoplastic polyimides and thermosetting polyimides with controlled reactivity

    NASA Astrophysics Data System (ADS)

    Zhuang, Hong

    1998-11-01

    Phosphorus containing monomers, bis(3-aminophenyl)methyl phosphine oxide (m-DAMPO) and bis(3-aminophenyl)phenyl phosphine oxide (m-DAPPO), were synthesized and incorporated into a thermoplastic poly(arylene ether imide) based upon 2,2sp'-bis (4-(3,4-dicarboxyphenoxy)phenyl) propane dianhydride and 1,3-phenylene diamine, in order to study their influence on flame resistance and other properties. DAMPO or DAPPO were quantitatively incorporated in concentrations of 25, 50, 75 and 100 mole percent, using the "one pot" ester-acid method. The number average molecular weights of the prepared materials were controlled to 20,000g/mol by off-setting the stoichiometry and endcapping with phthalic anhydride. This strategy enabled one to distinguish the effects of the phosphine oxide incorporation from the influence of molecular weight. The resulting copolymers demonstrated a significant increase in char yield as a function of the phosphine oxide content, thus suggesting improved fire resistance. Glass transition temperatures similar to the control were determined by DSC analysis. Analysis of the mechanical behavior of the DAMPO system at room temperature showed that tensile strength and elongation at failure values were comparable to the control system, while the DAPPO containing copolymers were surprisingly brittle. The influence of the reactive endgroup on the synthesis, cure behavior and network properties of thermosetting polyetherimides was investigated. Reactive phenylacetylene, acetylene and maleimide terminated poly(ether imide) oligomers were prepared and characterized. Optimal reaction conditions were established to produce fully endcapped oligomers with imidized structures and controlled molecular weight. The phenylacetylene endcapped system was synthesized by a conventional ester-acid method. The acetylene endcapped system was prepared via modified ester-acid method and the maleimide endcapped system was fabricated utilizing an amic-acid route. It was determined

  15. Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor); Grimsley, Brian W. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor)

    2015-01-01

    A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

  16. LaRC-ITPI/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Working, Dennis C.

    1991-01-01

    As part of an effort to develop high performance structural resins for aerospace applications, work has continued on block copolymers containing imide and arylene ether segments. The arylene ether block used in this study contains a bulky fluorene group in the polymer backbone while the imide block contains an arylene ketone segment similar to that in the arylene ether block and has been named LaRC-ITPI. A series of imide/arylene ether block and segmented copolymers were prepared and characterized. Films were prepared from these copolymers and mechanical properties were measured.

  17. Block Copolymer Membranes for Biofuel Purification

    NASA Astrophysics Data System (ADS)

    Evren Ozcam, Ali; Balsara, Nitash

    2012-02-01

    Purification of biofuels such as ethanol is a matter of considerable concern as they are produced in complex multicomponent fermentation broths. Our objective is to design pervaporation membranes for concentrating ethanol from dilute aqueous mixtures. Polystyrene-b-polydimethylsiloxane-b-polystyrene block copolymers were synthesized by anionic polymerization. The polydimethylsiloxane domains provide ethanol-transporting pathways, while the polystyrene domains provide structural integrity for the membrane. The morphology of the membranes is governed by the composition of the block copolymer while the size of the domains is governed by the molecular weight of the block copolymer. Pervaporation data as a function of these two parameters will be presented.

  18. Injectible bodily prosthetics employing methacrylic copolymer gels

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.

    2007-02-27

    The present invention provides novel block copolymers as structural supplements for injectible bodily prosthetics employed in medical or cosmetic procedures. The invention also includes the use of such block copolymers as nucleus pulposus replacement materials for the treatment of degenerative disc disorders and spinal injuries. The copolymers are constructed by polymerization of a tertiary amine methacrylate with either a (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer, such as the commercially available Pluronic.RTM. polymers, or a poly(ethylene glycol) methyl ether polymer.

  19. Biobased composites from thermoplastic polyurethane elastomer and cross-linked acrylated-epoxidized soybean oil

    USDA-ARS?s Scientific Manuscript database

    Soybean oil is an important sustainable material. Crosslinked acrylated epoxidized soybean oil (AESO) is brittle without flexibility and the incorporation of thermoplastic polyurethane improves its toughness for industrial applications. The hydrophilic functional groups from both oil and polyurethan...

  20. Relaxation map of a 100% green thermoplastic film. Glass transition and fragility

    NASA Astrophysics Data System (ADS)

    Saiter, J. M.; Dobircau, L.; Saiah, R.; Sreekumar, P. A.; Galandon, A.; Gattin, R.; Leblanc, N.; Adhikari, R.

    2010-02-01

    A 100% green thermoplastic obtained by extrusion of a mixture of wheat flour and plasticizers has been realized. The existence of two vitreous phases in this 100% green thermoplastic film has been pointed out by means of calorimetric measurements ( T g=-56 °C and T g=10 °C) and confirmed by electron microscopy. The molecular dynamics have been investigated by means of DMA measurements for temperature domains in the vicinity of the glass transition of each phase. We show that each phase exhibits a molecular dynamic characteristic of a fragile glass liquid former. The size of the cooperative domain engaged in the relaxation processes have also been estimated and we show that this new green thermoplastic exhibits relaxation mechanisms as expected for a conventional thermoplastic, as for instance a PMMA.

  1. A review of recent developments in joining high-performance thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Cole, K. C.

    1991-06-01

    There is currently a great deal of interest in the use of thermoplastic polymers as matrices in fiber reinforced composites for high performance applications, such as those encountered in the aerospace industry. These materials include polyether ether ketone (PEEK), polyphenylene sulphide (PPS), polyetherimide (PEI), polyamideimide (PAI), polyamides, polyimides, and polysulphones. A literature review is provided on the different ways of joining high performance thermoplastic composites by adhesive and fusion bonding. The discussion on adhesive bonding includes examination of the performance of specific adhesive/thermoplastic combinations and of techniques for the preparation of composite surfaces: abrasion, etching, flame, and plasma treatments. Thermoplastic composite welding techniques discussed in depth include the following: heated press welding, resistance welding, induction welding, and ultrasonic welding. Works which examine or compare applications for these bonding techniques are also reviewed.

  2. Preprosthetic minor tooth movement with thermoplastic appliances and interproximal stripping: a clinical report.

    PubMed

    Cho, Seok-Hwan

    2014-11-01

    This clinical report describes preprosthodontic minor tooth movement with serial thermoplastic appliances and interproximal stripping. A patient with rotated and labially tipped anterior teeth sought care with a request for improved appearance. The prosthodontic planning and treatment approach are discussed.

  3. Damage healing ability of a shape-memory-polymer-based particulate composite with small thermoplastic contents

    NASA Astrophysics Data System (ADS)

    Nji, Jones; Li, Guoqiang

    2012-02-01

    The purpose of this study is to investigate the potential of a shape-memory-polymer (SMP)-based particulate composite to heal structural-length scale damage with small thermoplastic additive contents through a close-then-heal (CTH) self-healing scheme that was introduced in a previous study (Li and Uppu 2010 Comput. Sci. Technol. 70 1419-27). The idea is to achieve reasonable healing efficiencies with minimal sacrifice in structural load capacity. By first closing cracks, the gap between two crack surfaces is narrowed and a lesser amount of thermoplastic particles is required to achieve healing. The particulate composite was fabricated by dispersing copolyester thermoplastic particles in a shape memory polymer matrix. It is found that, for small thermoplastic contents of less than 10%, the CTH scheme followed in this study heals structural-length scale damage in the SMP particulate composite to a meaningful extent and with less sacrifice of structural capacity.

  4. Thermosetting epoxy resin/thermoplastic system with combined shape memory and self-healing properties

    NASA Astrophysics Data System (ADS)

    Yao, Yongtao; Wang, Jingjie; Lu, Haibao; Xu, Ben; Fu, Yongqing; Liu, Yanju; Leng, Jinsong

    2016-01-01

    A novel and facile strategy was proposed to construct a thermosetting/thermoplastic system with both shape memory and self-healing properties based on commercial epoxy resin and poly(ɛ-caprolactone)-PCL. Thermoplastic material is capable of re-structuring and changing the stiffness/modulus when the temperature is above melting temperature. PCL microfiber was used as a plasticizer in epoxy resin-based blends, and served as a ‘hard segment’ to fix a temporary shape of the composites during shape memory cycles. In this study, the electrospun PCL membrane with a porous network structure enabled a homogenous PCL fibrous distribution and optimized interaction between fiber and epoxy resin. The self-healing capability is achieved by phase transition during curing of the composites. The mechanism of the shape memory effect of the thermosetting (rubber)/thermoplastic composite is attributed to the structural design of the thermoplastic network inside the thermosetting resin/rubber matrix.

  5. Diode Laser Assisted Filament Winding of Thermoplastic Matrix Composites

    PubMed Central

    Quadrini, Fabrizio; Squeo, Erica Anna; Prosperi, Claudia

    2010-01-01

    A new consolidation method for the laser-assisted filament winding of thermoplastic prepregs is discussed: for the first time a diode laser is used, as well as long glass fiber reinforced polypropylene prepregs. A consolidation apparatus was built by means of a CNC motion table, a stepper motor and a simple tensioner. Preliminary tests were performed in a hoop winding configuration: only the winding speed was changed, and all the other process parameters (laser power, distance from the laser focus, consolidation force) were kept constant. Small wound rings with an internal diameter of 25 mm were produced and compression tests were carried out to evaluate the composite agglomeration in dependence of the winding speed. At lower winding speeds, a strong interpenetration of adjacent layers was observed.

  6. Water-Assisted Production of Thermoplastic Nanocomposites: A Review

    PubMed Central

    Karger-Kocsis, József; Kmetty, Ákos; Lendvai, László; Drakopoulos, Stavros X.; Bárány, Tamás

    2014-01-01

    Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basically a combination of solution-assisted and traditional melt mixing methods. It is an emerging technique to overcome several disadvantages of the above two. Water or aqueous liquids with additives, do not work merely as temporary carrier materials of suitable nanofillers. During batchwise and continuous compounding, these liquids are fully or partly evaporated. In the latter case, the residual liquid is working as a plasticizer. This processing technique contributes to a better dispersion of the nanofillers and affects markedly the morphology and properties of the resulting nanocomposites. A survey is given below on the present praxis and possible future developments of water-assisted melt mixing techniques for the production of thermoplastic nanocomposites. PMID:28787925

  7. Multiphase design of autonomic self-healing thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Chen, Yulin; Kushner, Aaron M.; Williams, Gregory A.; Guan, Zhibin

    2012-06-01

    The development of polymers that can spontaneously repair themselves after mechanical damage would significantly improve the safety, lifetime, energy efficiency and environmental impact of man-made materials. Most approaches to self-healing materials require the input of external energy, healing agents, solvent or plasticizer. Despite intense research in this area, the synthesis of a stiff material with intrinsic self-healing ability remains a key challenge. Here, we show a design of multiphase supramolecular thermoplastic elastomers that combine high modulus and toughness with spontaneous healing capability. The designed hydrogen-bonding brush polymers self-assemble into a hard-soft microphase-separated system, combining the enhanced stiffness and toughness of nanocomposites with the self-healing capability of dynamic supramolecular assemblies. In contrast to previous self-healing polymers, this new system spontaneously self-heals as a single-component solid material at ambient conditions, without the need for any external stimulus, healing agent, plasticizer or solvent.

  8. Processing Optimization of Deformed Plain Woven Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    Smith, John R.; Vaidya, Uday K.

    2013-12-01

    This research addresses the processing optimization of post-manufactured, plain weave architecture composite panels consisted of four glass layers and thermoplastic polyurethane (TPU) when formed with only localized heating. Often times, during the production of deep drawn composite parts, a fabric preform experiences various defects, including non-isothermal heating and thickness variations. Minimizing these defects is of utmost importance for mass produceability in a practical manufacturing process. The broad objective of this research was to implement a design of experiments approach to minimize through-thickness composite panel variation during manufacturing by varying the heating time, the temperature of heated components and the clamping pressure. It was concluded that the heated tooling with least area contact was most influential, followed by the length of heating time and the amount of clamping pressure.

  9. An automated technique for manufacturing thermoplastic stringers in continuous length

    NASA Astrophysics Data System (ADS)

    Pantelakis, Sp.; Baxevani, E.; Spelz, U.

    In the present work an automated Continuous Compression Moulding Technique for the manufacture of stringers in continuous length is presented. The method combines pultrusion and hot-pressing. The technique is utilized for the production of L-shape stringers which are widely applied in aerospace constructions. The investigation was carried out on carbon reinforced PEEK (C/PEEK), as well as, for comparison, on the thermoplastic composites carbon reinforced polyethersulfon (C/PES), glass and carbon reinforced polyphenylene-sulfide (G/PPS, C/PPS) and Kevlar reinforced Polyamide 6 (K/PA 6). For the materials investigated the optimized process parameters for manufacturing the L-shape stringers were derived experimentally. To achieve this goal, the quality of the produced parts was controlled by using non-destructive testing techniques. Parts providing satisfactory quality were also tested destructively to measure their mechanical properties. The investigation results have shown the suitability of the technique to produce continuous length stringers.

  10. Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Gilwee, W. J., Jr.; Parker, J. A.

    1979-01-01

    The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated include polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated include epoxy, bismaleimide, a modified phenolic, and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass-reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented, and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

  11. Modeling Fatigue Damage in Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

    2009-10-30

    This paper applies a fatigue damage model recently developed for injection-molded long-fiber thermoplastics (LFTs) to predict the modulus reduction and fatigue lifetime of glass/polyamide 6,6 (PA6,6) specimens. The fatigue model uses a multiscale mechanistic approach to describe fatigue damage accumulation in these materials subjected to cyclic loading. Micromechanical modeling using a modified Eshelby-Mori-Tanaka approach combined with averaging techniques for fiber length and orientation distributions is performed to establish the stiffness reduction relation for the composite as a function of the microcrack volume fraction. Next, continuum damage mechanics and a thermodynamic formulation are used to derive the constitutive relations and the damage evolution law. The fatigue damage model has been implemented in the ABAQUS finite element code and has been applied to analyze fatigue of the studied glass/PA6,6 specimens. The predictions agree well with the experimental results.

  12. Fabrication of metallic glass micro grooves by thermoplastic forming

    NASA Astrophysics Data System (ADS)

    Wang, Fengyan; Zhang, Hong; Liang, Xiong; Gong, Feng; Ma, Jiang

    2017-02-01

    Metallic glasses (MGs) are considered as ideal materials for miniature fabrication because of their excellent thermoplastic forming ability in the supercooled liquid region. We show that Pd-based MG micro grooves, which are essential for microdluidic devices, can be prepared by a highly efficient and precise fabrication method. The scanning electron microscope observation and surface profiler measurement show that the MG micro grooves have superior dimensional accuracy. The excellent corrosion resistance of MGs compared with silicon, which is the conventional microfluidic device material, is also proved by the weight-loss corrosion method. Our results indicate that MG can be a promising candidate material for the fabrication of microfluidic devices and may have broad applications in the biomedical areas.

  13. Nanoscale pattern fidelity and transfer of hierarchically patterned thermoplastics films

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Kulkarni, Manish; Marshall, Allan; Douglas, Jack; Karim, Alamgir; the university of akron Team

    2015-03-01

    We demonstrate a versatile and inexpensive method for controlling the surface relief structure of both flexible elastomeric and glassy polymer films over large areas through a two-step imprinting process. First, nanoscale patterns were formed by nanoimprinting polymer films with a pattern on a DVD disk, obtained originally by nanoimprinting from a lithographically etched master pattern on a silicon wafer; micron-scale patterns were then superimposed on the nanoimprinted films by exposing them to ultraviolet radiation in oxygen (UVO) through a TEM grid mask having variable micron-scale patterning. This simple two-stage imprinting method allows for facile fabrication of hierarchically structured elastomer and thermoplastic polymer films. Besides, the thermodynamic properties of dewetting phenomenon of polystyrene film under the confinement of hierarchically patterned PDMS is studied.

  14. Tape Placement Head for Applying Thermoplastic Tape to an Object

    NASA Technical Reports Server (NTRS)

    Cope, Ralph D. (Inventor); Funck, Steve B. (Inventor); Gruber, Mark B. (Inventor); Lamontia, Mark A. (Inventor); Johnson, Anthony D. (Inventor)

    2008-01-01

    A tape placement head for applying thermoplastic tape to an object includes a heated feeder which guides the tape/tow to a heated zone. The heated zone has a line compactor having a single row of at least one movable heated member. An area compactor is located in the heated zone downstream from the line compactor. The area compactor includes a plurality of rows of movable feet which are extendable toward the tape/tow different distances with respect to each other to conform to the shape of the object. A shim is located between the heated compactors and the tape/tow. A chilled compactor is in a chilled zone downstream from the heated zone. The chilled zone includes a line chilled compactor and an area chilled compactor. A chilled shim is mounted between the chilled compactor and the tape/tow.

  15. Permittivity measurement of thermoplastic composites at elevated temperature.

    PubMed

    Ku, H S; Horsfield, B; Ball, J A; Siores, E

    2001-01-01

    The material properties of greatest importance in microwave processing of a dielectric are the complex relative permittivity epsilon = epsilon'-jepsilon", and the loss tangent, tan delta = epsilon"/epsilon'. This paper describes two convenient laboratory based methods to obtain epsilon', epsilon" and hence tan delta of fibre-reinforced thermoplastic (FRTP) composites. One method employs a microwave network analyzer in conjunction with a waveguide transmission technique, chosen because it provides the widest possible frequency range with high accuracy. The values of the dielectric constant and dielectric loss of glass fibre reinforced (33%) low density polyethylene, LDPE/GF (33%), polystyrene, PS/GF (33%), and Nylon 66/GF (33%), were obtained. Results are compared with those obtained by another method using a high-temperature dielectric probe.

  16. Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Gilwee, W. J., Jr.; Parker, J. A.

    1979-01-01

    The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated include polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated include epoxy, bismaleimide, a modified phenolic, and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass-reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented, and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

  17. Multiphase design of autonomic self-healing thermoplastic elastomers.

    PubMed

    Chen, Yulin; Kushner, Aaron M; Williams, Gregory A; Guan, Zhibin

    2012-04-01

    The development of polymers that can spontaneously repair themselves after mechanical damage would significantly improve the safety, lifetime, energy efficiency and environmental impact of man-made materials. Most approaches to self-healing materials require the input of external energy, healing agents, solvent or plasticizer. Despite intense research in this area, the synthesis of a stiff material with intrinsic self-healing ability remains a key challenge. Here, we show a design of multiphase supramolecular thermoplastic elastomers that combine high modulus and toughness with spontaneous healing capability. The designed hydrogen-bonding brush polymers self-assemble into a hard-soft microphase-separated system, combining the enhanced stiffness and toughness of nanocomposites with the self-healing capability of dynamic supramolecular assemblies. In contrast to previous self-healing polymers, this new system spontaneously self-heals as a single-component solid material at ambient conditions, without the need for any external stimulus, healing agent, plasticizer or solvent.

  18. Intrinsic manufacture of hollow thermoplastic composite/metal structures

    NASA Astrophysics Data System (ADS)

    Barfuss, Daniel; Grützner, Raik; Garthaus, Christian; Gude, Maik; Müller, Roland; Langrebe, Dirk

    2016-10-01

    In contrast to common and classical joining technologies for composite/metal hybrid structures such as bonding and riveting, profile and contour joints offer a promising potential for novel lightweight hybrid structures. First and foremost, joining systems with a form closure function enable to pass very high loads into rod- and tube-shaped fibre reinforced structures and achieve high degrees of material utilization for the composite part. This paper demonstrates the theoretical and technological principals for a resource efficient design and production of highly loaded thermoplastic composite profile structures with integrated metallic load introduction elements and a multi scale form closure. The hybrid structures are produced in an integral blow moulding process in which a braided tape-preform is simultaneously consolidated and formed into the metallic load introduction element. These metallic load introduction elements are manufactured in a two-stage process of external and internal hydroforming, after forming simulations have assured process stability for consistent quality.

  19. Microcellular Foams Based on High Performance Thermoplastic Nanocomposites

    SciTech Connect

    Sorrentino, Luigi; Iannace, Salvatore; Gargiulo, Marcella; Pezzullo, Giuseppe

    2010-06-02

    Foams from engineering thermoplastics nanocomposites based on Polyethersulphone and Polyethylene-2,6-naphthalate were prepared by using two different nanofillers (Silica nanoparticles and Graphite nanosheets). The effects of the nanofiller type and content on the foaming process was investigated and related to the density and cellular morphology of foams. The nanocomposite foams based on PES matrix exhibited improved nucleated cells both with SiO{sub 2} and Graphite nanosheets, but the density increased at all temperatures. On the contrary, nanocomposite foams based on PEN matrix showed different behaviors with the filler type. In this case, in fact, silica nanoparticles allowed lower densities when compared to the unfilled polymer foams, without influencing cells density. The Graphite nanosheets extended towards higher temperatures the foaming window of PEN nanocomposites, allowing densities as low as 0.15 at 260 deg. C.

  20. Production and properties of micro-cellulose reinforced thermoplastic starch

    NASA Astrophysics Data System (ADS)

    Kmetty, Á.; Karger-Kocsis, J.; Czigány, T.

    2015-02-01

    Thermoplastic starch (TPS)/micro-fibrillated cellulose (MFC) composites were prepared from maize starch with different amount of distilled water, glycerol and cellulose reinforcement. The components were homogenized by kneader and twin roll technique. The produced TPS and TPS-based polymer composites were qualified by static and dynamic mechanical tests and their morphology was analysed by microscopic techniques. The results showed that the amount of water and the order of the production steps control the properties of both the TPS and its MFC reinforced version. With increasing content of MFC the stiffness and strength of the TPS matrix increased, as expected. Microscopic inspection revealed that the TPS has a homogenous structure and the MFC is well dispersed therein when suitable preparation conditions were selected.

  1. Adjustable forming of thermoplastic composites for orthopaedic applications.

    PubMed

    Hou, M; Friedrich, K

    1998-02-01

    The present study was focused on the development of a special thermoforming technique for manufacturing of continuous fibre reinforced thermoplastic composite parts with complex surface contours. In particular, a stamp forming process was modified to investigate the potential manufacturing advantages of thermoplastic composites in orthopaedic applications. An apparatus was designed which allowed the thermoforming procedure to be fully automatic, i.e. a cold pre-consolidated laminate panel, as the feed material, was heated up in an infrared heating zone and then transferred into a cold mould system, where it was stamp formed. Both halves of the mould were made of many tiny round metal sticks in a metal frame. This needle-bed mould allowed one to copy any contour by pushing it slightly on spring fixed sticks. The desired position of these sticks could then be adjusted by forcing the side plates of the metal frame together. To prevent any press mark of stick-tops on the composite, i.e. to achieve smooth surfaces of the themoformed composite parts, flexible rubber pads were needed to cover the mould surfaces. Experimental results showed that the surface profile of CF/PP and GF/PP composites formed by the needle-bed mould reproduced fairly well the contour of a saddle shaped, complex model sample. Unique properties of this needle-bed mould are that it can be repeatedly used, and that it can copy any complex surface contours, for example a bone surface, by simply adjusting the stick positions according to the special surface requirements.

  2. Field Testing of Thermoplastic Encapsulants in High-Temperature Installations

    DOE PAGES

    Kempe, Michael D.; Miller, David C.; Wohlgemuth, John H.; ...

    2015-11-01

    Recently there has been increased interest in using thermoplastic encapsulant materials in photovoltaic modules, but concerns have been raised about whether these would be mechanically stable at high temperatures in the field. This has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. We constructed eight pairs of crystalline-silicon modules and eight pairs of glass/encapsulation/glass thin-film mock modules using different encapsulant materials, of which only two were formulated to chemically crosslink. One module set was exposed outdoors with thermal insulation on the back side in Mesa, Arizona, in the summer (hot-dry), and an identicalmore » module set was exposed in environmental chambers. High-precision creep measurements (±20 μm) and electrical performance measurements indicate that despite many of these polymeric materials operating in the melt or rubbery state during outdoor deployment, no significant creep was seen because of their high viscosity, lower operating temperature at the edges, and/or the formation of chemical crosslinks in many of the encapsulants with age despite the absence of a crosslinking agent. Only an ethylene-vinyl acetate (EVA) encapsulant formulated without a peroxide crosslinking agent crept significantly. When the crystalline-silicon modules, the physical restraint of the backsheet reduced creep further and was not detectable even for the EVA without peroxide. Because of the propensity of some polymeric materials to crosslink as they age, typical thermoplastic encapsulants would be unlikely to result in creep in the vast majority of installations.« less

  3. Color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for non metal clasp denture

    PubMed Central

    Jang, Dae-Eun; Lee, Ji-Young; Jang, Hyun-Seon; Lee, Jang-Jae

    2015-01-01

    PURPOSE The aim of this study was to compare the color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for the non-metal clasp dentures to those of thermoplastic polyamide and conventional heat-polymerized denture base resins. MATERIALS AND METHODS Three types of denture base resin, which are conventional heat-polymerized acrylic resin (Paladent 20), thermoplastic polyamide resin (Bio Tone), thermoplastic acrylic resin (Acrytone) were used as materials for this study. One hundred five specimens were fabricated. For the color stability test, specimens were immersed in the coffee and green tee for 1 and 8 weeks. Color change was measured by spectrometer. Water sorption was tested after 1 and 8 weeks immersion in the water. For the test of cytotoxicity, cell viability assay was measured and cell attachment was analyzed by FE-SEM. RESULTS All types of denture base resin showed color changes after 1 and 8 weeks immersion. However, there was no significant difference between denture base resins. All specimens showed significant color changes in the coffee than green tee. In water sorption test, thermoplastic acrylic resin showed lower values than conventional heat-polymerized acrylic resin and thermoplastic polyamide resin. Three types of denture base showed low cytotoxicity in cell viability assay. Thermoplastic acrylic resin showed the similar cell attachment but more stable attachment than conventional heat-polymerized acrylic resin. CONCLUSION Thermoplastic acrylic resin for the non-metal clasp denture showed acceptable color stability, water sorption and cytotoxicity. To verify the long stability in the mouth, additional in vitro studies are needed. PMID:26330974

  4. Photoinitiated grafting of porous polymer monoliths and thermoplastic polymers for microfluidic devices

    DOEpatents

    Frechet, Jean M. J. [Oakland, CA; Svec, Frantisek [Alameda, CA; Rohr, Thomas [Leiden, NL

    2008-10-07

    A microfluidic device preferably made of a thermoplastic polymer that includes a channel or a multiplicity of channels whose surfaces are modified by photografting. The device further includes a porous polymer monolith prepared via UV initiated polymerization within the channel, and functionalization of the pore surface of the monolith using photografting. Processes for making such surface modifications of thermoplastic polymers and porous polymer monoliths are set forth.

  5. The crystallization of tough thermoplastic resins in the presence of carbon fibers

    NASA Technical Reports Server (NTRS)

    Theil, M. H.

    1986-01-01

    The crystallization kinetics of the thermoplastic resins poly(phenylene sulfide) (PPS) and poly(aryl-ether-ether-ketone) (PEEK) in the presence and in the abscence of carbon fibers was studied. How carbon fiber surfaces in composites affect the crystallization of tough thermoplastic polymers that may serve as matrix resins were determined. The crystallization kinetics of such substances can provide useful information about the crystallization mechanisms and, thus, indicate if the presence of carbon fibers cause any changes in such mechanisms.

  6. FIBER LENGTH DISTRIBUTION MEASUREMENT FOR LONG GLASS AND CARBON FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil; Frame, Barbara J; Nguyen, Ba N.; TuckerIII, Charles L.; Velez-Garcia, Gregorio

    2007-01-01

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7 mm (1/2 in.) using equipment optimized for molding short fiber reinforced thermoplastics.

  7. Separating effective high density polyethylene segments from olefin block copolymers using high temperature liquid chromatography with a preloaded discrete adsorption promoting solvent barrier.

    PubMed

    Chatterjee, Tirtha; Rickard, Mark A; Pearce, Eric; Pangburn, Todd O; Li, Yongfu; Lyons, John W; Cong, Rongjuan; deGroot, A Willem; Meunier, David M

    2016-09-23

    Recent advances in catalyst technology have enabled the synthesis of olefin block copolymers (OBC). One type is a "hard-soft" OBC with a high density polyethylene (HDPE) block and a relatively low density polyethylene (VLDPE) block targeted as thermoplastic elastomers. Presently, one of the major challenges is to fractionate HDPE segments from the other components in an experimental OBC sample (block copolymers and VLDPE segments). Interactive high temperature liquid chromatography (HTLC) is ineffective for OBC separation as the HDPE segments and block copolymer chains experience nearly identical enthalpic interactions with the stationary phase and co-elute. In this work we have overcome this challenge by using liquid chromatography under the limiting conditions of desorption (LC LCD). A solvent plug (discrete barrier) is introduced in front of the sample which specifically promotes the adsorption of HDPE segments on the stationary phase (porous graphitic carbon). Under selected thermodynamic conditions, VLDPE segments and block copolymer chains crossed the barrier while HDPE segments followed the pore-included barrier solvent and thus enabled separation. The barrier solvent composition was optimized and the chemical composition of fractionated polymer chains was investigated as a function of barrier solvent strength using an online Fourier-transform infrared (FTIR) detector. Our study revealed that both the HDPE segments as well as asymmetric block copolymer chains (HDPE block length≫VLDPE block length) are retained in the separation and the barrier strength can be tailored to retain a particular composition. At the optimum barrier solvent composition, this method can be applied to separate effective HDPE segments from the other components, which has been demonstrated using an experimental OBC sample. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Organosilane Polymers. III. Block Copolymers.

    DTIC Science & Technology

    1980-04-01

    5446 (1969) 9) R. West, J. Polym. Sci., C, 29, 65 (1970) 10) V.F. Traven and R. West, J. Am. Chem. Soc., 95, 6824 (1973) 11) W.G. Boberski and-A.L...COMPOSITION Alkyl H/Aryl H (2 ) Copolymer Method,1 , Calculated Found 111-3 A 0.72 0.73 B 0.72 0.73 111-5 A 0.80 0.85 B 0.80 0.80 111-8 A 1.0 1.4 B 1.0...1.1 (1) A: Chloro-oligomer added to lithio-oligomer. B : Lithio-oligomer added to chloro-oligomer. (2) By HI-NMR TABLE 2 INFRA-RED ABSORPTIONS

  9. Curable polyphosphazene copolymers and terpolymers

    NASA Technical Reports Server (NTRS)

    Reynard, Kennard A. (Inventor); Rose, Selwyn H. (Inventor)

    1976-01-01

    Copolymers and terpolymers comprising randomly repeating units represented by the general formulae ##EQU1## wherein the R' radicals contain OH functionality and R being at least one member of the group of monovalent radicals selected from alkyl, substituted alkyl, aryl, substituted aryl and arylalkyl, and R' is represented by ##EQU2## wherein Q represents either --(CH.sub.2).sub. n or --C.sub.6 H.sub.4 X(CH.sub.2).sub. m, the --X(CH.sub.2).sub. m group being either meta or para and n is an integer from 1 to 6, m is an integer from 1 to 3, X is O or CH.sub.2, and R is H or a lower alkyl radical with up to four carbon atoms (methyl, ethyl, etc.). The ratio of R to R' is between 99.5 to 0.5 and 65 to 35.

  10. Salt Complexation in Block Copolymer Thin Films

    SciTech Connect

    Kim,S.; Misner, M.; Yang, L.; Gang, O.; Ocko, B.; Russell, T.

    2006-01-01

    Ion complexation within cylinder-forming block copolymer thin films was found to affect the ordering process of the copolymer films during solvent annealing, significantly enhancing the long-range positional order. Small amounts of alkali halide or metal salts were added to PS-b-PEO, on the order of a few ions per chain, where the salt complexed with the PEO block. The orientation of the cylindrical microdomains strongly depended on the salt concentration and the ability of the ions to complex with PEO. The process shows large flexibility in the choice of salt used, including gold or cobalt salts, whereby well-organized patterns of nanoparticles can be generated inside the copolymer microdomains. By further increasing the amount of added salts, the copolymer remained highly ordered at large degrees of swelling and demonstrated long-range positional correlations of the microdomains in the swollen state, which holds promise as a route to addressable media.

  11. Electrostatic control of block copolymer morphology

    NASA Astrophysics Data System (ADS)

    Sing, Charles E.; Zwanikken, Jos W.; Olvera de La Cruz, Monica

    2014-07-01

    Energy storage is at present one of the foremost issues society faces. However, material challenges now serve as bottlenecks in technological progress. Lithium-ion batteries are the current gold standard to meet energy storage needs; however, they are limited owing to the inherent instability of liquid electrolytes. Block copolymers can self-assemble into nanostructures that simultaneously facilitate ion transport and provide mechanical stability. The ions themselves have a profound, yet previously unpredictable, effect on how these nanostructures assemble and thus the efficiency of ion transport. Here we demonstrate that varying the charge of a block copolymer is a powerful mechanism to predictably tune nanostructures. In particular, we demonstrate that highly asymmetric charge cohesion effects can induce the formation of nanostructures that are inaccessible to conventional uncharged block copolymers, including percolated phases desired for ion transport. This vastly expands the design space for block copolymer materials and is informative for the versatile design of battery electrolyte materials.

  12. Arbitrary lattice symmetries via block copolymer nanomeshes

    PubMed Central

    Majewski, Pawel W.; Rahman, Atikur; Black, Charles T.; Yager, Kevin G.

    2015-01-01

    Self-assembly of block copolymers is a powerful motif for spontaneously forming well-defined nanostructures over macroscopic areas. Yet, the inherent energy minimization criteria of self-assembly give rise to a limited library of structures; diblock copolymers naturally form spheres on a cubic lattice, hexagonally packed cylinders and alternating lamellae. Here, we demonstrate multicomponent nanomeshes with any desired lattice symmetry. We exploit photothermal annealing to rapidly order and align block copolymer phases over macroscopic areas, combined with conversion of the self-assembled organic phase into inorganic replicas. Repeated photothermal processing independently aligns successive layers, providing full control of the size, symmetry and composition of the nanoscale unit cell. We construct a variety of symmetries, most of which are not natively formed by block copolymers, including squares, rhombuses, rectangles and triangles. In fact, we demonstrate all possible two-dimensional Bravais lattices. Finally, we elucidate the influence of nanostructure on the electrical and optical properties of nanomeshes. PMID:26100566

  13. Morphologies in Sulfonated Styrenic Pentablock Copolymer Membranes

    NASA Astrophysics Data System (ADS)

    Choi, Jae-Hong; Bramson, Matt; Winey, Karen I.

    2010-03-01

    Membranes of pentablock and triblock copolymers consisting of poly(tert-butyl styrene) (TBS), hydrogenated polyisoprene (HI), and partially sulfonated poly(styrene-ran-styrene sulfonate) (SS) were studied using small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The TBS-HI-SS-HI-TBS pentablock and TBS-HI-SS triblock copolymer membranes exhibit anisotropic microphase separated morphologies. Because the pentablock and triblock copolymers can be expected to have complex morphologies, thermal annealing was conducted to promote well-defined morphologies. The annealed membranes exhibit stronger peaks and more high order reflections in SAXS patterns, as well as better defined microstructures in the TEM. Electron microcopy studies with various staining protocols are underway to establish the morphology of the pentablock copolymer membranes including the size and shape of the three microdomains (TBS, HI and SS). We gratefully acknowledge Kraton Polymers, Inc. for materials.

  14. Block copolymer structures in nano-pores

    NASA Astrophysics Data System (ADS)

    Pinna, Marco; Guo, Xiaohu; Zvelindovsky, Andrei

    2010-03-01

    We present results of coarse-grained computer modelling of block copolymer systems in cylindrical and spherical nanopores on Cell Dynamics Simulation. We study both cylindrical and spherical pores and systematically investigate structures formed by lamellar, cylinders and spherical block copolymer systems for various pore radii and affinity of block copolymer blocks to the pore walls. The obtained structures include: standing lamellae and cylinders, ``onions,'' cylinder ``knitting balls,'' ``golf-ball,'' layered spherical, ``virus''-like and mixed morphologies with T-junctions and U-type defects [1]. Kinetics of the structure formation and the differences with planar films are discussed. Our simulations suggest that novel porous nano-containers can be formed by confining block copolymers in pores of different geometries [1,2]. [4pt] [1] M. Pinna, X. Guo, A.V. Zvelindovsky, Polymer 49, 2797 (2008).[0pt] [2] M. Pinna, X. Guo, A.V. Zvelindovsky, J. Chem. Phys. 131, 214902 (2009).

  15. Evaluation of adhesion of reline resins to the thermoplastic denture base resin for non-metal clasp denture.

    PubMed

    Kim, Ji Hye; Choe, Han Cheol; Son, Mee Kyoung

    2014-01-01

    This study aimed to evaluate the tensile and transverse bond strength of chairside reline resins (Tokuyama Rebase II, Mild Rebaron LC) to a thermoplastic acrylic resin (Acrytone) used for non metal clasp denture. The results were compared with those of a conventional heat polymerized acrylic resin (Paladent 20) and a thermoplastic polyamide resin (Biotone). The failure sites were examined by scanning electron microscopy to evaluate the mode of failure. As results, the bond strength of reline resins to a thermoplastic acrylic resin was similar to the value of a conventional heat polymerized acrylic resin. However, thermoplastic polyamide resin showed the lowest value. The results of this study indicated that a thermoplastic acrylic resin for non metal clasps denture allows chairside reline and repair. It was also found that the light-polymerized reline resin had better bond strength than the autopolymerizing reline resin in relining for a conventional heat polymerized acrylic resin and a thermoplastic acrylic resin.

  16. Method for making block siloxane copolymers

    DOEpatents

    Butler, N.L.; Jessop, E.S.; Kolb, J.R.

    1981-02-25

    A method for synthesizing block polysiloxane copolymers is disclosed. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

  17. Responsive Copolymers for Enhanced Petroleum Recovery

    SciTech Connect

    McCormick, C.; Hester, R.

    2001-02-27

    The objectives of this work was to: synthesize responsive copolymer systems; characterize molecular structure and solution behavior; measure rheological properties of aqueous fluids in fixed geometry flow profiles; and to tailor final polymer compositions for in situ rheology control under simulated conditions. This report focuses on the synthesis and characterization of novel stimuli responsive copolymers, the investigation of dilute polymer solutions in extensional flow and the design of a rheometer capable of measuring very dilute aqueous polymer solutions at low torque.

  18. Reactivity ratios for organotin copolymer systems.

    PubMed

    El-Newehy, Mohamed H; Al-Deyab, Salem S; Al-Hazmi, Ali Mohsen Ali

    2010-04-15

    Di(tri-n-butyltin) itaconate (DTBTI) and monoethyl tributyltin fumarate (METBTF) were synthesized as organotin monomers. The organotin monomers were copolymerized with styrene (ST) and methyl methacrylate (MMA) via a free radical polymerization technique. The overall conversion was kept low (copolymer composition was determined from tin analysis. The synthesized monomers and copolymers were characterized by elemental analysis, 1H- and 13C-NMR, and FTIR spectroscopy.

  19. Method for making block siloxane copolymers

    DOEpatents

    Butler, Nora; Jessop, Edward S.; Kolb, John R.

    1982-01-01

    A method for synthesizing block polysiloxane copolymers. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

  20. ABA and ABC type thermoplastic elastomer toughening of epoxy matrices and its effect on carbon fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Pitchiaya, Gomatheeshwar

    Epoxy-matrices have high modulus, strength, excellent creep resistance, but lacks ductility. One approach to improve the mechanical toughness is the addition of thermoplastic elastomers (TPEs). The TPEs investigated here are triblock copolymers of styrene-butadiene-methyl methacrylate (SBM) and methylmethacrylate-butylacrylate-methylmethacrylate (MAM) of the ABC and ABA type, respectively. The effect of concentration (1-12.5 wt %) of these TPEs on a diglycidyl ether of bisphenol-A (DGEBA) epoxy cured with metaphenylenediamine (mPDA), has been investigated. The TPE-DGEBA epoxies were characterized by TGA, DMA, SEM and impact. The flexural modulus, flexural strength and thermal resistance remained unaffected up to 5 wt% loading of TPEs, and exhibited less than 10% decrease at higher weight percent. T g was unaffected for all concentrations. Fracture toughness was improved 250% and up to 375% (when non- stoichiometric amount of curing agent was used) with TPE addition to epoxy/mPDA matrix. A SBM(1phr)EPON system was chosen to be the matrix of choice for a fiber reinforced composite system with a 4wt% aromatic epoxy sizing on a AS4 (UV-treated) carbon fiber. The 0° and 90° flexural modulus and strength of a SBM modified system was compared with the neat and their fracture surfaces were analyzed. A 89% increase in flexural strength was observed in a 90° flexural test for the modified system when compared with the neat. Novel sizing agents were also developed to enhance interfacial shear strength (IFSS) and the fiber-matrix adhesion and their birefringence pattern were analyzed.

  1. Diffusion of copolymers composed of monomers with drastically different friction factors in copolymer/homopolymer blends

    NASA Astrophysics Data System (ADS)

    Duranty, Edward R.; Baschnagel, Jörg; Dadmun, Mark

    2017-02-01

    Copolymers are commonly used as interface modifiers that allow for the compatibilization of polymer components in a blend. For copolymers to function as a compatibilizer, they must diffuse through the matrix of the blend to the interface between the two blend components. The diffusivity of a copolymer in a blend matrix therefore becomes important in determining good candidates for use as compatibilizers. In this work, coarse-grained Monte Carlo simulations using the bond fluctuation model modified with an overlap penalty have been developed to study the diffusive behavior of PS/PMMA random copolymers in a PMMA homopolymer blend. The simulations vary the connectivity between different monomers, the thermodynamic interactions between the monomers which manifest within a chain, and between copolymer and homopolymer matrix and define the monomer friction coefficient of each component independently, allowing for the determination of the combined effect of these parameters on copolymer chain diffusion. The results of this work indicate that PS-r-PMMA copolymer diffusion is not linearly dependent on the copolymer composition on a logarithmic scale, but its diffusion is a balance of the kinetics governed by the dominant motion of the faster styrene monomers and thermodynamics, which are governed by the concentration of styrene monomer within a given monomer's local volume.

  2. Diffusion of copolymers composed of monomers with drastically different friction factors in copolymer/homopolymer blends

    DOE PAGES

    Duranty, Edward R.; Baschnagel, Jörg; Dadmun, Mark

    2017-02-07

    Copolymers are commonly used as interface modifiers that allow for the compatibilization of polymer components in a blend. For copolymers to function as a compatibilizer, they must diffuse through the matrix of the blend to the interface between the two blend components. The diffusivity of a copolymer in a blend matrix therefore becomes important in determining good candidates for use as compatibilizers. In this paper, coarse-grained Monte Carlo simulations using the bond fluctuation model modified with an overlap penalty have been developed to study the diffusive behavior of PS/PMMA random copolymers in a PMMA homopolymer blend. The simulations vary themore » connectivity between different monomers, the thermodynamic interactions between the monomers which manifest within a chain, and between copolymer and homopolymer matrix and define the monomer friction coefficient of each component independently, allowing for the determination of the combined effect of these parameters on copolymer chain diffusion. Finally, the results of this work indicate that PS-r-PMMA copolymer diffusion is not linearly dependent on the copolymer composition on a logarithmic scale, but its diffusion is a balance of the kinetics governed by the dominant motion of the faster styrene monomers and thermodynamics, which are governed by the concentration of styrene monomer within a given monomer’s local volume.« less

  3. Polyhydroxyalkanoate copolymers from forest biomass.

    PubMed

    Keenan, Thomas M; Nakas, James P; Tanenbaum, Stuart W

    2006-07-01

    The potential for the use of woody biomass in poly-beta-hydroxyalkanoate (PHA) biosynthesis is reviewed. Based on previously cited work indicating incorporation of xylose or levulinic acid (LA) into PHAs by several bacterial strains, we have initiated a study for exploring bioconversion of forest resources to technically relevant copolymers. Initially, PHA was synthesized in shake-flask cultures of Burkholderia cepacia grown on 2.2% (w/v) xylose, periodically amended with varying concentrations of levulinic acid [0.07-0.67% (w/v)]. Yields of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) [P(3HB-co-3HV)] from 1.3 to 4.2 g/l were obtained and could be modulated to contain from 1.0 to 61 mol% 3-hydroxyvalerate (3HV), as determined by 1H and 13C NMR analyses. No evidence for either the 3HB or 4HV monomers was found. Characterization of these P(3HB-co-3HV) samples, which ranged in molecular mass (viscometric, Mv) from 511-919 kDa, by differential scanning calorimetry and thermogravimetric analyses (TGA) provided data which were in agreement for previously reported P(3HB-co-3HV) copolymers. For these samples, it was noted that melting temperature (Tm) and glass transition temperature (Tg) decreased as a function of 3HVcontent, with Tm demonstrating a pseudoeutectic profile as a function of mol% 3HV content. In order to extend these findings to the use of hemicellulosic process streams as an inexpensive carbon source, a detoxification procedure involving sequential overliming and activated charcoal treatments was developed. Two such detoxified process hydrolysates (NREL CF: aspen and CESF: maple) were each fermented with appropriate LA supplementation. For the NREL CF hydrolysate-based cultures amended with 0.25-0.5% LA, P(3HB-co-3HV) yields, PHA contents (PHA as percent of dry biomass), and mol% 3HV compositions of 2.0 g/l, 40% (w/w), and 16-52 mol% were obtained, respectively. Similarly, the CESF hydrolysate-based shake-flask cultures yielded 1.6 g/l PHA, 39% (w

  4. Random hydrophilic-hydrophobic copolymers

    NASA Astrophysics Data System (ADS)

    Garel, T.; Leibler, L.; Orland, H.

    1994-12-01

    We study a single statistical amphiphilic copolymer chain AB in a selective solvent (e.g. water). Two situations are considered. In the annealed case, hydrophilic (A) and hydrophobic (B) monomers are at local chemical equilibrium and both the fraction of A monomers and their location along the chain can vary, whereas in the quenched case (which is relevant to proteins), the chemical sequence along the chain is fixed by synthesis. In both cases, the physical behaviour depends on the average hydrophobicity of the polymer chain. For a strongly hydrophobic chain (large fraction of B), we find an ordinary continuous θ collapse, with a large conformational entropy in the collapsed phase. For a weakly hydrophobic, or a hydrophilic chain, there is an unusual first-order collapse transition. In particular, for the case of Gaussian disorder, this discontinuous transition is driven by a change of sign of the third virial coefficient. The entropy of this collapsed phase is strongly reduced with respect to the θ collapsed phase. Nous étudions un copolymère aléatoire amphiphile AB dans un solvant sélectif (par exemple, de l'eau). Nous considérons deux cas. Dans le cas du désordre mobile, les monomères hydrophiles (A) et hydrophobes (B) sont à l'équilibre chimique local, et la fraction de monomères A ainsi que leur position dans l'espace peuvent varier, alors que dans le cas du désordre gelé (qui est relié au problème des protéines), la séquence chimique est fixée par synthèse. Dans les deux cas, le comportement de la chaîne depend de son hydrophobicité moyenne. Pour une chaîne fortement hydrophobe (grande fraction de B), on trouve un point d'effondrement θ continu ordinaire, avec une grande entropie conformationnelle. Pour une chaîne faiblement hydrophobe ou hydrophile, on trouve une transition inhabituelle du premier ordre. En particulier, dans le cas du désordre gaussien, cette transition discontinue est pilotée par un changement de signe du troisi

  5. Initiator Effects in Reactive Extrusion of Starch Graft Copolymers

    USDA-ARS?s Scientific Manuscript database

    Graft copolymers of starch with water-soluble polymers such as polyacrylamide have potential applications including hydrogels, superabsorbents, and thickening agents. Reactive extrusion is a rapid, continuous method for production of starch graft copolymers with high reaction and grafting efficienc...

  6. Hydrogen-bonded aggregates in precise acid copolymers

    SciTech Connect

    Lueth, Christopher A.; Bolintineanu, Dan S.; Stevens, Mark J. Frischknecht, Amalie L.

    2014-02-07

    We perform atomistic molecular dynamics simulations of melts of four precise acid copolymers, two poly(ethylene-co-acrylic acid) (PEAA) copolymers, and two poly(ethylene-co-sulfonic acid) (PESA) copolymers. The acid groups are spaced by either 9 or 21 carbons along the polymer backbones. Hydrogen bonding causes the acid groups to form aggregates. These aggregates give rise to a low wavevector peak in the structure factors, in agreement with X-ray scattering data for the PEAA materials. The structure factors for the PESA copolymers are very similar to those for the PEAA copolymers, indicating a similar distance between aggregates which depends on the spacer length but not on the nature of the acid group. The PEAA copolymers are found to form more dimers and other small aggregates than do the PESA copolymers, while the PESA copolymers have both more free acid groups and more large aggregates.

  7. Universal hydrophilic coating of thermoplastic polymers currently used in microfluidics.

    PubMed

    Zilio, Caterina; Sola, Laura; Damin, Francesco; Faggioni, Lucia; Chiari, Marcella

    2014-02-01

    A number of materials used to fabricate disposable microfluidic devices are hydrophobic in nature with water contact angles on their surface ranging from 80° to over 100°. This characteristic makes them unsuitable for a number of microfluidic applications. Both the wettability and analyte adsorption parameters are highly dependent on the surface hydrophobicity. In this article, we propose a general method to coat the surface of five materials: polydimethylsiloxane (PDMS), cyclic olefin copolymer (COC), polyethylene terephthalate (PET), polycarbonate (PC), and polytetrafluoroethylene (PTFE). This fast and robust process, which is easily implementable in any laboratory including microfabrication clean room facilities, was devised by combining gas-phase and wet chemical modification processes. Two different coatings that improve the surface hydrophilicity were prepared via the "dip and rinse" approach by immersing the plasma oxidized materials into an aqueous solution of two different poly(dimethylacrylamide) copolymers incorporating a silane moiety and functionalized with either N-acryloyloxysuccinimide (NAS) (poly(DMA-NAS-MAPS) or glycidyl methacrylate (GMA) (poly(DMA-GMA-MAPS). The coating formation was confirmed by contact angle (CA) analysis comparing the variation of CAs of uncoated and coated surfaces subjected to different aging treatments. The antifouling character of the polymer was demonstrated by fluorescence and interferometric detection of proteins adsorbed on the surafce. This method is of great interest in microfluidics due to its broad applicability to a number of materials with varying chemical compositions.

  8. Adhesion promotion with random copolymers

    NASA Astrophysics Data System (ADS)

    Simmons, Edward Read

    This thesis presents a study of adhesion promotion with random copolymers (RCP's). Monte Carlo (MC) simulations are used to study the potential use of RCP's as interfacial strengtheners at a homopolymer-solid interface. We discuss the effect of varying several design parameters of the RCP chains on interfacial strength. We find that RCP's can promote adhesion dependent upon careful selection of the parameters such as the RCP composition, blockiness, and concentration. We draw our conclusions from both equilibrium and non-equilibrium MC simulations in which we impose a normal stress on the interfacial chain system and observe the response as the system is deformed. These simulations are designed to reflect experimentally realizable conditions as closely as possible. The ultimate goal of our work is to guide experimentalists in the design and selection of the best adhesion promoter for a given system. With this goal in mind, we suggest several extensions of our methodology to further tighten the connection between simulation and experiment.

  9. Melt Rheology of Block Copolymers in Relation to Melt Structure.

    DTIC Science & Technology

    1980-06-23

    According to their theory, (A-B-A) type block copolymer melts are expected to exhibit a network response including a yield stress at very low shear rates ...observed the following very unusual flow behavior with SBS block copolymers . 1. The viscosities of SBS block copolymers at low shear rates go...unusual flow properties. One can expect from the probable two-phase structure in the melt that block copolymer melts would exhibit strong elastic

  10. Charge Transport in Conjugated Block Copolymers

    NASA Astrophysics Data System (ADS)

    Smith, Brandon; Le, Thinh; Lee, Youngmin; Gomez, Enrique

    Interest in conjugated block copolymers for high performance organic photovoltaic applications has increased considerably in recent years. Polymer/fullerene mixtures for conventional bulk heterojunction devices, such as P3HT:PCBM, are severely limited in control over interfaces and domain length scales. In contrast, microphase separated block copolymers self-assemble to form lamellar morphologies with alternating electron donor and acceptor domains, thereby maximizing electronic coupling and local order at interfaces. Efficiencies as high as 3% have been reported in solar cells for one block copolymer, P3HT-PFTBT, but the details concerning charge transport within copolymers have not been explored. To fill this gap, we probed the transport characteristics with thin-film transistors. Excellent charge mobility values for electron transport have been observed on aluminum source and drain contacts in a bottom gate, bottom contact transistor configuration. Evidence of high mobility in ordered PFTBT phases has also been obtained following thermal annealing. The insights gleaned from our investigation serve as useful guideposts, revealing the significance of the interplay between charge mobility, interfacial order, and optimal domain size in organic block copolymer semiconductors.

  11. Morphology study in block copolymer electrolytes

    NASA Astrophysics Data System (ADS)

    Mullin, Scott; Wanakule, Nisita; Balsara, Nitash

    2008-03-01

    Poly(styrene-b-ethylene oxide)/lithium bis(trifluoromethane)sulfonimide (SEO/LiTFSI) is of interest in battery applications since the doped PEO phase can conduct ions and the glassy PS phase can prevent dendrite growth upon recharging. It is believed that the LiTFSI molecules are localized in the PEO microphases. Previous studies have shown that highly conducting electrolytes can be made from symmetric SEO copolymers. The purpose of this study is to explore the conductivity of asymmetric SEO copolymer systems doped with LiTFSI. Our studies encompass both neat asymmetric SEO copolymers and SEO copolymers blended with PS homopolymers to separate the effects of architecture of the copolymer molecules and morphology adopted by the system in the melt state. Conductivity is measured by AC impedance, morphology is determined by small angle X-ray scattering, and crystallinity of the PEO chains is determined by differential scanning calorimetry. All samples were prepared in hermetically sealed sample cells in an Argon glovebox.

  12. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the following...

  13. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be safely...

  14. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may... produced by the polymerization of methacrylic acid and divinylbenzene. The divinylbenzene functions as a...

  15. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be safely...

  16. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be safely...

  17. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the following...

  18. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the following...

  19. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  20. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  1. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide... of this section, ethylene-carbon monoxide copolymers (CAS Reg. No. 25052-62-4) consist of the...

  2. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  3. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  4. 21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Styrene-maleic anhydride copolymers. 177.1820... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1820 Styrene-maleic anhydride copolymers. Styrene-maleic anhydride copolymers identified in paragraph (a) of this section may be...

  5. 40 CFR 721.484 - Fluorinated acrylic copolymer (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fluorinated acrylic copolymer (generic... Specific Chemical Substances § 721.484 Fluorinated acrylic copolymer (generic name). (a) Chemical substance... fluorinated acrylic copolymer (PMN P-95-1208) is subject to reporting under this section for the...

  6. 40 CFR 721.484 - Fluorinated acrylic copolymer (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Fluorinated acrylic copolymer (generic... Specific Chemical Substances § 721.484 Fluorinated acrylic copolymer (generic name). (a) Chemical substance... fluorinated acrylic copolymer (PMN P-95-1208) is subject to reporting under this section for the...

  7. 40 CFR 721.10519 - Perfluoroalkyl acrylate copolymer (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Perfluoroalkyl acrylate copolymer... Specific Chemical Substances § 721.10519 Perfluoroalkyl acrylate copolymer (generic). (a) Chemical... as perfluoroalkyl acrylate copolymer (PMN P-11-63) is subject to reporting under this section for the...

  8. 40 CFR 721.10519 - Perfluoroalkyl acrylate copolymer (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Perfluoroalkyl acrylate copolymer... Specific Chemical Substances § 721.10519 Perfluoroalkyl acrylate copolymer (generic). (a) Chemical... as perfluoroalkyl acrylate copolymer (PMN P-11-63) is subject to reporting under this section for the...

  9. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false n-Alkylglutarimide/acrylic copolymers. 177.1060... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic copolymers identified in this section may be safely used as articles...

  10. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false n-Alkylglutarimide/acrylic copolymers. 177.1060... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic copolymers identified in this section may be safely used as articles...

  11. Structure Confirmation and Properties of Poly(Dimethylsiloxaneco-diethylsiloxane) Copolymer

    NASA Astrophysics Data System (ADS)

    Gao, Li-Juan; Ma, De-Peng; Feng, Sheng-Yu

    2016-05-01

    High molecular weight poly (dimethylsiloxane-co-diethylsiloxane) (PMES) copolymer was synthesized by anionic ring opening polymerization. Its composition and structures was determined by 29Si NMR spectroscopy. A random microstructure of copolymer was observed in the 29Si NMR spectrum. Further, PMES was characterized by GPC and DSC. The results show that PMES is crystallization-free copolymer with low glass transition temperatures.

  12. pH-sensitive methacrylic copolymers and the production thereof

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

    2007-01-09

    The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

  13. pH-sensitive methacrylic copolymers and the production thereof

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

    2006-02-14

    The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

  14. 21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-ethyl acrylate copolymers. 177.1320... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1320 Ethylene-ethyl acrylate copolymers. Ethylene-ethyl acrylate copolymers may be safely used to produce packaging materials,...

  15. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-vinyl acetate copolymers. 177.1350... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  16. 21 CFR 177.1950 - Vinyl chloride-ethylene copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl chloride-ethylene copolymers. 177.1950... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1950 Vinyl chloride-ethylene copolymers. The vinyl chloride-ethylene copolymers identified in paragraph (a) of this section may be...

  17. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  18. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-vinyl acetate copolymers. 177.1350... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  19. 21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-ethyl acrylate copolymers. 177.1320... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1320 Ethylene-ethyl acrylate copolymers. Ethylene-ethyl acrylate copolymers may be safely used to produce packaging materials,...

  20. 21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-ethyl acrylate copolymers. 177.1320... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1320 Ethylene-ethyl acrylate copolymers. Ethylene-ethyl acrylate copolymers may be safely used to produce packaging materials,...