Sample records for thermoplastic puncture-healing polymers

  1. Recent Advances in Thermoplastic Puncture-Healing Polymers

    NASA Technical Reports Server (NTRS)

    Gordon, K. L.; Working, D. C.; Wise, K. E.; Bogert, P. B.; Britton, S. M.; Topping, C.C.; Smith, J. Y.; Siochi, E. J.

    2009-01-01

    Self-healing materials provide a route for enhanced damage tolerance in materials for aerospace applications. In particular, puncture-healing upon impact has the potential to mitigate significant damage caused by high velocity micrometeoroid impacts. This type of material also has the potential to improve damage tolerance in load bearing structures to enhance vehicle health and aircraft durability. The materials being studied are those capable of instantaneous puncture healing, providing a mechanism for mechanical property retention in lightweight structures. These systems have demonstrated healing capability following penetration of fast moving projectiles -- velocities that range from 9 mm bullets shot from a gun (approx.330 m/sec) to close to micrometeoroid debris velocities of 4800 m/sec. In this presentation, we report on a suite of polymeric materials possessing this characteristic. Figure 1 illustrates the puncture healing concept. Puncture healing in these materials is dependent upon how the combination of a polymer's viscoelastic properties responds to the energy input resulting from the puncture event. Projectile penetration increases the temperature in the vicinity of the impact. Self-healing behavior occurs following puncture, whereby energy must be transferred to the material during impact both elastically and inelastically, thus establishing two requirements for puncture healing to occur: a.) The need for the puncture event to produce a local melt state in the polymer material and b.) The molten material has to have sufficient melt elasticity to snap back and close the hole. 1,2 Previous ballistic testing studies revealed that Surlyn materials warmed up to a temperature approx.98 C during projectile puncture (3 C higher than it s melting temperature). 1,2 The temperature increase produces a localized flow state and the melt elasticity to snap back thus sealing the hole. Table 1 lists the commercially polymers studied here, together with their physical properties. The polymers were selected based on chemical structure, tensile strengths, tensile moduli, glass transition temperature, melting temperatures, and impact strength. The thermal properties of the polymers were characterized by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Mechanical properties were assessed by a Sintech 2W instron according to ASTM D1708 or D638 at crosshead speeds of 5.08 cm/min. 7.6 cm x 7.6 cm panels of the different materials were prepared and ballistic testing was performed at various temperatures. The panels were shot with a .223 caliber semiautomatic rifle from a distance of 23 meters at various temperatures. Chronographs were used to measure initial and final bullet velocity. Temperatures at the site of impact were measured using a FLIR ThermaCAM S60 thermal camera. A Vision Research model Phantom 9 high speed video camera was used to capture high speed video footage of ballistics testing.

  2. Recent Advances in Thermoplastic Puncture-Healing Polymers

    NASA Technical Reports Server (NTRS)

    Bogert, Philip B.; Working, Dennis C.; Wise, Kristopher E.; Smith, Janice Y.; Topping, Crystal C.; Britton, Sean M.; Bagby, Paul R.; Siochi, Emilie J.

    2010-01-01

    The motivation for this work is to develop self-healing polymeric materials to enable damage tolerant systems, and to tailor puncture healing for use temperatures and applications. This will be a benefit in environments and conditions where access for manual repair is limited or impossible, or where damage may not be detected.

  3. Bonding thermoplastic polymers

    DOEpatents

    Wallow, Thomas I. (Fremont, CA); Hunter, Marion C. (Livermore, CA); Krafcik, Karen Lee (Livermore, CA); Morales, Alfredo M. (Livermore, CA); Simmons, Blake A. (San Francisco, CA); Domeier, Linda A. (Danville, CA)

    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.

  4. 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.

  5. Bonding of thermoplastic polymer microfluidics

    Microsoft Academic Search

    Chia-Wen Tsao; Don L. DeVoe

    2009-01-01

    Thermoplastics are highly attractive substrate materials for microfluidic systems, with important benefits in the development\\u000a of low cost disposable devices for a host of bioanalytical applications. While significant research activity has been directed\\u000a towards the formation of microfluidic components in a wide range of thermoplastics, sealing of these components is required\\u000a for the formation of enclosed microchannels and other microfluidic

  6. 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.

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

    PubMed

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

    2012-09-01

    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 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. PMID:22900539

  8. 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

  9. 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 plasticizer content was increased, the gelatinization temperature increased for glycerol, sorbitol and diglycerol, but it moved in the opposite direction in the case of polyglycerol. The gelatinization temperature variation for glycerol, sorbitol and diglycerol caused by changing water and plasticizer content indicates that water is the primary agent causing granular swell and plasticization in the gelatinization process. Due to the high molecular weight and viscosity, as well as the low hydroxyl group density (~ one --OH per two carbon) and borderline solubility of polyglycerol in water, it is believed that water-aided penetration of the plasticizer among the crystalline structure of starch molecules is significantly decelerated. So it is proposed that in the case of low-water solubility of the plasticizers, gelatinization temperature is determined more by the total amount of the plasticizer and water, rather than the water/plasticizer ratio. Increasing the miscibility of polyglycerol in water by increasing the temperature of the initial slurry, results in a return of the system to the typical thermal dependence of gelatinization with plasticizer/water ratio. Secondly, the gelatinization of starch under "dynamic conditions" was studied. In this case, a constant shear is applied to the slurry, along with a temperature ramp to induce gelatinization. This is, in fact, a rheological technique that heats up the slurry, while a mechanical shear is applied throughout. The reason for using this method is that in the plastic industry, thermoplastic starch is produced via processes involving shear such as extrusion, but, to date, there has not yet been a thorough study on the effect of pure shear on the gelatinization process. Glycerol, diglycerol and sorbitol were subjected to different dynamic gelatinization treatments in a couette flow system, and the results were compared with static gelatinization. Applying shear showed virtually no effect on the onset gelatinization temperature. However, the conclusion temperature was remarkably reduced

  10. Thermodynamics of deformation for thermoplastic polymers

    SciTech Connect

    Adams, G.W.

    1987-01-01

    The post-yielding behavior of some common thermoplastics was examined in uniaxial tension to determine if these materials were ideally plastic from a thermodynamic viewpoint. Various polyethylenes, poly(methyl methacrylate) and polycarbonate, polyarylate and polysulfone based on bisphenol A were studied. Thermodynamic measurements were made during deformation using a novel isothermal deformation calorimeter capable of measuring the work and heat of deformation. Thermodynamically ideal plasticity was not observed for any of the polymers examined. The polyethylenes stored approximately 30% of the input work as a latent internal energy change while this value was 40-50% for the amorphous glasses. Differential-scanning-calorimetry results for the deformed polyethylenes indicated that the heats of transition were less for the drawn samples than for the isotropic samples. This result was primarily due to the stored deformation energy and was not necessarily indicative of a change in crystallinity. Additional experiments were performed to determine the mechanism of deformation energy storage and to ascertain the implications of this stored energy in engineering applications.

  11. 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.

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

    Microsoft Academic Search

    M. Heckele; W. K. Schomburg

    2004-01-01

    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,

  13. Effects of Surface Plasma Treatment on Tribology of Thermoplastic Polymers

    E-print Network

    North Texas, University of

    Effects of Surface Plasma Treatment on Tribology of Thermoplastic Polymers Alexander Bismarck,1- fore normally altered by plasma treatment. Wetting prop- erties--which correspond to surface energy) to atmospheric pressure oxygen plasma treatment for varying amounts of time. Effects of the treatment have been

  14. 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.

  15. Puncture-Healing Properties of Carbon Nanotube-Filled Ionomers

    NASA Technical Reports Server (NTRS)

    Ward, Thomas C.

    2003-01-01

    Ionomers are polymers that contain ionic groups in relatively low concentrations along the polymer backbone. These ionic groups, in the presence of oppositely charged ions, form aggregates that lead to novel physical properties of the polymer. React-A-Seal(trademark) and Surlyn(trademark) are poly(ethylene-co-methacrylic acid) (EMAA) ionomer-based materials and Nucrel(trademark) is the EMAA acid copolymer neutralized to produce Surlyn(trademark). React-A-Seal(trademark), Surlyn(trademark), and Nucrel(trademark) recover into their original shapes following a high impact puncture at velocities ranging from 300 to 1200 ft/s ('self-healing'). This self-healing process may be of great benefit in space applications where structures are exposed to matter impacts. A thermal IR camera indicated a temperature increase to 98 C for Nucrel(trademark) 925, Surlyn(trademark) 8940, React-A-Seal(trademark), and Surlyn(trademark) 8920 after initial penetration. To understand and generalize the observed phenomena, questions concerning the mechanism of the puncture resealing must be answered. One suggestion is that the elastic character of the melt created by the puncture drives the self-healing. This inference is based on the observed temperature rise of approx. 3 C above the melting temperature of the samples (approx. 95 C) during the impact. With the expectation of gaining additional insight into the self-healing phenomenon, a thermodynamic and viscoelastic investigation was conducted using primarily DSC and DMA. Surlyn(trademark) and React-A-Seal(trademark) showed the characteristic order-disorder transition at approx. 52 C that has been reported in literature. Master curves were constructed from the creep isotherms for the four EMAA samples. An aging study was performed to investigate the irreproducibility and "tailing effect" observed in the creep data. The aging study indicated that, with increased aging time and temperature, changes in the polyethylene matrix lead to complexities in morphology resulting in changes in the magnitude and shape of the creep curves.

  16. 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.

  17. 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.

  18. Blends of thermoplastic and elastomeric matrices with liquid crystalline polymers

    SciTech Connect

    Roggero, A.; Pedretti, U.; La Mantia, F.P. [Eniricerche, Milanese (Italy)

    1995-12-01

    Liquid crystalline polymers (LCPs) present a unique balance of properties and, when added to thermoplastic (TP) or elastomeric (EL) matrices, can impart to the relevant blends specific properties that can be utilized for specific applications. As regards TP/LCP blends, the proclivity of LCPs to form fibrous structures and their low melt viscositiy allowed to obtain blends reinforced and easier to process than the pure TPs: particularly, depending on the LCP-TP structures and on the processing parameters, materials with improved processability, high modulus, enhanced impact strength and creeping resistance were obtained. As regards EL/LCP blends, that based on fluoroelastomers were in depth investigated and offered outstanding properties.

  19. 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.

  20. Bonding of thermoplastic polymer microfluidics Chia-Wen Tsao Don L. DeVoe

    E-print Network

    Rubloff, Gary W.

    REVIEW Bonding of thermoplastic polymer microfluidics Chia-Wen Tsao Ã? Don L. DeVoe Received: 20 Abstract Thermoplastics are highly attractive substrate materials for microfluidic systems, with important microchannels and other microfluidic elements, and thus bonding remains a critical step in any thermo- plastic

  1. 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.

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

    Microsoft Academic Search

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

    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

  3. Relative toxicity of the pyrolysis products from some thermoplastic and thermoset polymers

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Gilwee, W. J., Jr.; Hilado, C. J.

    1978-01-01

    Relative toxicity data on the pyrolysis products of a variety of thermoplastic and thermoset polymers are presented. The data are presented in terms of time to incapacitation and time to death with a fixed sample weight of 1.0 g, and in terms of the apparent lethal concentration required to produce 50 percent mortality within a fixed exposure period of 30 min.

  4. Review of potential processing techniques for the encapsulation of wastes in thermoplastic polymers

    SciTech Connect

    Patel, B.R.; Lageraaen, P.R.; Kalb, P.D.

    1995-08-01

    Thermoplastic encapsulation has been extensively studied at Brookhaven National Laboratory`s (BNL) Environmental and Waste Technology Center (EWTC) as a waste encapsulation technology applicable to a wide range of waste types including radioactive, hazardous and mixed wastes. Encapsulation involves processing thermoplastic and waste materials into a waste form product by heating and mixing both materials into a homogeneous molten mixture. Cooling of the melt results in a solid monolithic waste form in which contaminants have been completely surrounded by a polymer matrix. Heating and mixing requirements for successful waste encapsulation can be met using proven technologies available in various types of commercial equipment. Processing techniques for thermoplastic materials, such as low density polyethylene (LDPE), are well established within the plastics industry. The majority of commercial polymer processing is accomplished using extruders, mixers or a combination of these technologies. Extruders and mixers are available in a broad range of designs and are used during the manufacture of consumer and commercial products as well as for compounding applications. Compounding which refers to mixing additives such as stabilizers and/or colorants with polymers, is analogous to thermoplastic encapsulation. Several processing technologies were investigated for their potential application in encapsulating residual sorbent waste in selected thermoplastic polymers, including single-screw extruders, twin-screw extruders, continuous mixers, batch mixers as well as other less conventional devices. Each was evaluated based on operational ease, quality control, waste handling capabilities as well as degree of waste pretreatment required. Based on literature review, this report provides a description of polymer processing technologies, a discussion of the merits and limitations of each and an evaluation of their applicability to the encapsulation of sorbent wastes.

  5. Noncontact Microembossing Technology for Fabricating Thermoplastic Optical Polymer Microlens Array Sheets

    PubMed Central

    Chang, Xuefeng; Ge, Xiaohong; Li, Hui

    2014-01-01

    Thermoplastic optical polymers have replaced traditional optical glass for many applications, due to their superior optical performance, mechanical characteristics, low cost, and efficient production process. This paper investigates noncontact microembossing technology used for producing microlens arrays made out of PMMA (polymethyl methacrylate), PS (polyStyrene), and PC (polycarbonate) from a quartz mold, with microhole arrays. An array of planoconvex microlenses are formed because of surface tension caused by applying pressure to the edge of a hole at a certain glass transition temperature. We studied the principle of noncontact microembossing techniques using finite element analysis, in addition to the thermal and mechanical properties of the three polymers. Then, the independently developed hot-embossing equipment was used to fabricate microlens arrays on PMMA, PS, and PC sheets. This is a promising technique for fabricating diverse thermoplastic optical polymer microlens array sheets, with a simple technological process and low production costs. PMID:25162063

  6. Welding methods for joining thermoplastic polymers for the hermetic enclosure of medical devices.

    PubMed

    Amanat, Negin; James, Natalie L; McKenzie, David R

    2010-09-01

    New high performance polymers have been developed that challenge traditional encapsulation materials for permanent active medical implants. The gold standard for hermetic encapsulation for implants is a titanium enclosure which is sealed using laser welding. Polymers may be an alternative encapsulation material. Although many polymers are biocompatible, and permeability of polymers may be reduced to acceptable levels, the ability to create a hermetic join with an extended life remains the barrier to widespread acceptance of polymers for this application. This article provides an overview of the current techniques used for direct bonding of polymers, with a focus on thermoplastics. Thermal bonding methods are feasible, but some take too long and/or require two stage processing. Some methods are not suitable because of excessive heat load which may be delivered to sensitive components within the capsule. Laser welding is presented as the method of choice; however the establishment of suitable laser process parameters will require significant research. PMID:20570545

  7. Cold Spray Coating Deposition Mechanism on the Thermoplastic and Thermosetting Polymer Substrates

    NASA Astrophysics Data System (ADS)

    Ganesan, Amirthan; Yamada, Motohiro; Fukumoto, Masahiro

    2013-12-01

    Cold spraying is a successful and promising coating technique for many engineering applications due to its high-rate and high-dense coating development abilities. Nevertheless, their practical use in polymer substrate is still in the fledgling phase. There are very few articles about the cold spray coating on polymers; however, the interaction of metallic particle with the polymer substrate is poorly understood, and thus a thick coating has not successfully been developed on the polymer substrate. In order to rationalize as full as possible the entire behavior of the high velocity particle with the polymer substrate, we used thermoplastic and thermosetting polymer materials as substrates. The particle behaviors with the substrate were observed under various gas pressure and temperature, and with various particles feed rate. The result showed that the particle behaviors were unique with respect to the substrate. Also it was clearly understood that the metal particles not experienced any plastic deformation due to the soft nature of the polymer substrates. The particles attached to the thermoplastic substrate either through adhesive bonding and/or mechanical inter locking, whereas only pure localized fracture observed on the thermosetting substrate and thus no particles attached firmly on the substrate.

  8. Thermodynamics of water sorption in high performance glassy thermoplastic polymers

    PubMed Central

    Scherillo, Giuseppe; Petretta, Mauro; Galizia, Michele; La Manna, Pietro; Musto, Pellegrino; Mensitieri, Giuseppe

    2014-01-01

    Sorption thermodynamics of water in two glassy polymers, polyetherimide (PEI) and polyetheretherketone (PEEK), is investigated by coupling gravimetry and on line FTIR spectroscopy in order to gather information on the total amount of sorbed water as well as on the different species of water molecules absorbed within the polymers, addressing the issue of cross- and self-interactions occurring in the polymer/water systems. Water sorption isotherms have been determined at temperatures ranging from 30 to 70°C while FTIR spectroscopy has been performed only at 30°C. The experimental analysis provided information on the groups present on the polymer backbones involved in hydrogen bonding interactions with absorbed water molecules. Moreover, it also supplied qualitative indications about the different “populations” of water molecules present within the PEEK and a quantitative assessment of these “populations” in the case of PEI. The results of the experimental analysis have been interpreted using an equation of state theory based on a compressible lattice fluid model for the Gibbs energy of the polymer-water mixture, developed by extending to the case of out of equilibrium glassy polymers a previous model intended for equilibrium rubbery polymers. The model accounts for the non-equilibrium nature of glassy polymers as well as for mean field and for hydrogen bonding interactions, providing a satisfactory quantitative interpretation of the experimental data. PMID:24860802

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

    SciTech Connect

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

    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.

  10. RHEOLOGICAL PROPERTIES & MOLECULAR WEIGHT DISTRIBUTIONS OF FOUR PERFLUORINATED THERMOPLASTIC POLYMERS

    SciTech Connect

    Hoffman, D M; Shields, A L

    2009-02-24

    Dynamic viscosity measurements and molecular weight estimates have been made on four commercial, amorphous fluoropolymers with glass transitions (Tg) above 100 C: Teflon AF 1600, Hyflon AD 60, Cytop A and Cytop M. These polymers are of interest as binders for the insensitive high explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) because of their high density and Tg above ambient, but within a suitable processing range of TATB. As part of this effort, the rheological properties and molecular weight distributions of these polymers were evaluated.

  11. Roles of work of adhesion between carbon blacks and thermoplastic polymers on electrical properties of composites.

    PubMed

    Park, Soo-Jin; Kim, Hyun-Chel; Kim, Hak-Yong

    2002-11-01

    The effect of the work of adhesion between carbon blacks and different thermoplastic polymers on the positive temperature coefficient (PTC) of composites was investigated. Thermoplastic polymers, such as EVA, LDPE, LLDPE, HDPE, and PP, were used with the addition of 30 wt% of carbon blacks. The work of adhesion based on the surface free energy of a composite was studied in the context of two-liquid contact angle measurements using deionized water and diiodomethane. It was observed that the resistivity on PTC behavior was greatly increased near the crystalline melting temperature, due to the thermal expansion of polymeric matrix. It was shown that the PTC intensity defined as the ratio of the maximum resistivity (rho(max)) to the resistivity at room temperature (rho(RT)) had the largest value on CB/HDPE composites. From the experimental results, the decrease in the work of adhesion induced by interactions between carbon black surfaces and polymer chains is an important factor in the fabrication of a PTC composite. PMID:12702379

  12. Selecting and designing with the right thermoplastic polymer for your microfluidic chip: a close look into cyclo-olefin polymer

    NASA Astrophysics Data System (ADS)

    Nevitt, Mark

    2013-03-01

    Engineers who are developing microfluidic devices and bioMEMs for life science applications have many aspects to consider when selecting the proper base materials for constructing a device. While glass and polydimethylsiloxane (PDMS) are the staple materials for proof-of-concept and prototype chip fabrication, they are not a feasible solution for commercial production due to their slow, labor-intensive production rate. Alternatively, a molded or extruded thermoplastic solution can deliver the precision, consistency, and high volume capability required for commercial scale production. Traditional thermoplastics, such as polymethylmethacrylate (PMMA), polycarbonate (PC), and polystyrene (PS), are well known by development engineers in the bioscience community; however, cyclo-olefin polymer (COP), a relative newcomer in the world of plastics, is gaining increasing attention for use in microfluidic devices due to its unique balance of key properties compared to conventional thermoplastics. In this paper, we provide a comprehensive look at the properties which make COP an excellent candidate for providing the flow cell support and reagent storage functions in microfluidic assays. We also explore the processing attributes and capabilities of COP resin and film which are crucial for manufacturing high-performance microfluidic devices.

  13. 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. PMID:24037663

  14. Development of micro-debond methods for thermoplastics including applications to liquid crystalline polymers

    SciTech Connect

    Sauer, B.B.; DiPaolo, N.V. [DuPont Central Research and Development, Wilmington, DE (United States)

    1995-12-01

    Micro-bead and related single fiber debond techniques were used to study adhesion of liquid crystalline copolyesters (LCPs) and other thermoplastic polymers to glass fibers. For polymers with poor flow, symmetric beads on fibers were difficult to prepare so an alternative but comparable sample preparation method was developed. Glass fibers of widely varying diameters were used in order to extend the dynamic range of the debond techniques in terms of debonding area, leading to an order of magnitude improvement in precision over that demonstrated previously with single fiber debond techniques. It was found that chemical bonding of the LCPs was quite favorable as was indicated by fracture surface analysis. The apparent poor interphase strength in fiber reinforced LCP composites is due to orientation of the LCP chains at the fiber surface leading to cohesive failure of the LCP near the interface. Reactive silane coupling agents lead to no improvement in interface strength as compared to bare glass as expected based on the failure mechanism.

  15. Study of Double-Side Ultrasonic Embossing for Fabrication of Microstructures on Thermoplastic Polymer Substrates

    PubMed Central

    Luo, Yi; Yan, Xu; Qi, Na; Wang, Xiaodong; Wang, Liangjiang

    2013-01-01

    Double-side replication of polymer substrates is beneficial to the design and the fabrication of 3-demensional devices. The ultrasonic embossing method is a promising, high efficiency and low cost replication method for thermoplastic substrates. It is convenient to apply silicon molds in ultrasonic embossing, because microstructures can be easily fabricated on silicon wafers with etching techniques. To reduce the risk of damaging to silicon molds and to improve the replication uniformity on both sides of the polymer substrates, thermal assisted ultrasonic embossing method was proposed and tested. The processing parameters for the replication of polymethyl methacrylate (PMMA), including ultrasonic amplitude, ultrasonic force, ultrasonic time, and thermal assisted temperature were studied using orthogonal array experiments. The influences of the substrate thickness, pattern style and density were also investigated. The experiment results show that the principal parameters for the upper and lower surface replication are ultrasonic amplitude and thermal assisted temperature, respectively. As to the replication uniformity on both sides, the ultrasonic force has the maximal influence. Using the optimized parameters, the replication rate reached 97.5% on both sides of the PMMA substrate, and the cycle time was less than 50 s. PMID:23630605

  16. Hemocompatibility of Inorganic Physical Vapor Deposition (PVD) Coatings on Thermoplastic Polyurethane Polymers

    PubMed Central

    Lackner, Juergen M.; Waldhauser, Wolfgang; Hartmann, Paul; Bruckert, Franz; Weidenhaupt, Marianne; Major, Roman; Sanak, Marek; Wiesinger, Martin; Heim, Daniel

    2012-01-01

    Biocompatibility improvements for blood contacting materials are of increasing interest for implanted devices and interventional tools. The current study focuses on inorganic (titanium, titanium nitride, titanium oxide) as well as diamond-like carbon (DLC) coating materials on polymer surfaces (thermoplastic polyurethane), deposited by magnetron sputtering und pulsed laser deposition at room temperature. DLC was used pure (a-C:H) as well as doped with silicon, titanium, and nitrogen + titanium (a-C:H:Si, a-C:H:Ti, a-C:H:N:Ti). In-vitro testing of the hemocompatibility requires mandatory dynamic test conditions to simulate in-vivo conditions, e.g., realized by a cone-and-plate analyzer. In such tests, titanium- and nitrogen-doped DLC and titanium nitride were found to be optimally anti-thrombotic and better than state-of-the-art polyurethane polymers. This is mainly due to the low tendency to platelet microparticle formation, a high content of remaining platelets in the whole blood after testing and low concentration of platelet activation and aggregation markers. Comparing this result to shear-flow induced cell motility tests with e.g., Dictostelium discoideum cell model organism reveals similar tendencies for the investigated materials. PMID:24955532

  17. Hemocompatibility of Inorganic Physical Vapor Deposition (PVD) Coatings on Thermoplastic Polyurethane Polymers.

    PubMed

    Lackner, Juergen M; Waldhauser, Wolfgang; Hartmann, Paul; Bruckert, Franz; Weidenhaupt, Marianne; Major, Roman; Sanak, Marek; Wiesinger, Martin; Heim, Daniel

    2012-01-01

    Biocompatibility improvements for blood contacting materials are of increasing interest for implanted devices and interventional tools. The current study focuses on inorganic (titanium, titanium nitride, titanium oxide) as well as diamond-like carbon (DLC) coating materials on polymer surfaces (thermoplastic polyurethane), deposited by magnetron sputtering und pulsed laser deposition at room temperature. DLC was used pure (a-C:H) as well as doped with silicon, titanium, and nitrogen + titanium (a-C:H:Si, a-C:H:Ti, a-C:H:N:Ti). In-vitro testing of the hemocompatibility requires mandatory dynamic test conditions to simulate in-vivo conditions, e.g., realized by a cone-and-plate analyzer. In such tests, titanium- and nitrogen-doped DLC and titanium nitride were found to be optimally anti-thrombotic and better than state-of-the-art polyurethane polymers. This is mainly due to the low tendency to platelet microparticle formation, a high content of remaining platelets in the whole blood after testing and low concentration of platelet activation and aggregation markers. Comparing this result to shear-flow induced cell motility tests with e.g., Dictostelium discoideum cell model organism reveals similar tendencies for the investigated materials. PMID:24955532

  18. Membrane consisting of polyquaternary amine ion exchange polymer network interpenetrating the chains of thermoplastic matrix polymer

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Wallace, C. J. (inventors)

    1978-01-01

    An ion exchange membrane was formed from a solution containing dissolved matrix polymer and a set of monomers which are capable of reacting to form a polyquaternary ion exchange material; for example vinyl pyride and a dihalo hydrocarbon. After casting solution and evaporation of the volatile component's, a relatively strong ion exchange membrane was obtained which is capable of removing anions, such as nitrate or chromate from water. The ion exchange polymer forms an interpenetrating network with the chains of the matrix polymer.

  19. Review of potential processing techniques for the encapsulation of wastes in thermoplastic polymers

    Microsoft Academic Search

    B. R. Patel; P. R. Lageraaen; P. D. Kalb

    1995-01-01

    Thermoplastic encapsulation has been extensively studied at Brookhaven National Laboratory`s (BNL) Environmental and Waste Technology Center (EWTC) as a waste encapsulation technology applicable to a wide range of waste types including radioactive, hazardous and mixed wastes. Encapsulation involves processing thermoplastic and waste materials into a waste form product by heating and mixing both materials into a homogeneous molten mixture. Cooling

  20. High Power Laser Cutting of Fiber Reinforced Thermoplastic Polymers with cw- and Pulsed Lasers

    NASA Astrophysics Data System (ADS)

    Schneider, F.; Wolf, N.; Petring, D.

    Glass fiber and carbon fiber reinforced polymers with thermoplastic matrix enable high volume production with short cycle times. Cutting and trimming operations in these production chains require the use of high average laser power for an efficient cutting speed, but employment of high laser power runs the risk to induce a wide heat affected zone (HAZ). This paper deals with investigations with cw and ns-pulsed CO2-laser radiation in the kilowatt range in single-pass and multiple-pass processes. Using multi-pass processing at high processing speeds of 100 m/min and above a reduced heat affected zone in the range of 100 ?m to 200 ?m could be achieved by the ns-pulsed radiation. With cw radiation at the same average power of 1 kW however, the HAZ was 300-400 ?m. Also employing ns-pulses in the kW-range average power leads to heat accumulation in the material. Small HAZ were obtained with sufficient break times between subsequent passes.

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

    SciTech Connect

    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.

  2. Fungal degradation of the thermoplastic polymer poly-?-hydroxybutyric acid (PHB) under simulated deep sea pressure

    Microsoft Academic Search

    K. E. Gonda; D. Jendrossek; H. P. Molitoris

    2000-01-01

    Little is known about marine filamentous fungi and yeasts, almost nothing about their life and metabolism under deep sea conditions. Data on growth and metabolic activity give insight into the role of organisms in the marine habitat. Degradation studies on pollutants, such as polymeric thermoplasts, provide information about the self-cleaning capacity of a habitat. Therefore, recently isolated fungal strains from

  3. Welding methods for joining thermoplastic polymers for the hermetic enclosure of medical devices

    Microsoft Academic Search

    Negin Amanat; Natalie L. James; David R. McKenzie

    2010-01-01

    New high performance polymers have been developed that challenge traditional encapsulation materials for permanent active medical implants. The gold standard for hermetic encapsulation for implants is a titanium enclosure which is sealed using laser welding. Polymers may be an alternative encapsulation material. Although many polymers are biocompatible, and permeability of polymers may be reduced to acceptable levels, the ability to

  4. The effects of physico-chemical interactions and polymer grafting on interfacial adhesion in thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Raghavendra, Venkat Krishna

    The effects of physico-chemical interactions between the carbon fiber and Bisphenol-A polycarbonate matrix was investigated to understand the factors governing the interfacial adhesion in thermoplastic matrix composites. It was found that, the changes in the amount of oxygen functionality achieved through electrochemical oxidative surface treatment of the carbon fibers didn't affect the level of adhesion, indicating negligible polar and hydrogen bond formation. Composites fabricated from these fibers that were subsequently passivated through thermal hydrogenation up to 1000°C, which removed all the oxygen functionality without affecting the fiber topography, indicated that the mechanical interlocking between the fiber and the matrix didn't have a strong influence on the interfacial adhesion. Grafting low molecular weight BPA-PC and high molecular weight PMMA on to the fiber surface improved the interfacial adhesion. However, the level of improvement was observed to be independent of the fiber surface treatment and the molecular weight of the grafted chains. These results are consistent with the cohesive zone models proposed for the chain pull out and chain scission observed in block copolymers.

  5. Assessment of physical properties of fibres from thermoplastic polymers by means of tensiometric tests

    Microsoft Academic Search

    H. Schmidt; K. Twarowska-Schmidt

    2010-01-01

    Several properties of fibres and monofilaments made from polymers such as polyamide 6 (PA), poly(ethylene terephthalate) (PET), polypropylene (PP), aliphatic polyester of butanediol, succinic and adipic acids (PBSA), aliphatic-aromatic polyester of butanediol, terephthalic and adipic acids (PBTA) have been studied. Wettability of monofilaments has been tested by dynamic contact angle method, so surface free energy of synthetic fibres could be

  6. Microinjection molding of thermoplastic polymers: morphological comparison with conventional injection molding

    NASA Astrophysics Data System (ADS)

    Giboz, Julien; Copponnex, Thierry; Mélé, Patrice

    2009-02-01

    The skin-core crystalline morphology of injection-molded semi-crystalline polymers is well documented in the scientific literature. The thermomechanical environment provokes temperature and shear gradients throughout the entire thickness of the part during molding, thus influencing the polymer crystallization. Crystalline morphologies of a high-density polyethylene (HDPE) micromolded part (?part) and a classical part (macropart) are compared with optical, thermal and x-ray diffraction analyses. Results show that the crystalline morphologies with regard to thickness vary between the two parts. While a 'skin-core' morphology is present for the macropart, the ?part exhibits a specific 'core-free' morphology, i.e. no spherulite is present at the center of the thickness. This result seems to be generated under the specific conditions used in microinjection molding that lead to the formation of smaller and more oriented crystalline entities.

  7. Low platinum loading electrodes for polymer electrolyte fuel cells fabricated using thermoplastic ionomers

    Microsoft Academic Search

    Mahlon S. Wilson; Judith A. Valerio; Shimshon Gottesfeld

    1995-01-01

    Low platinum loading catalyst layers for polymer electrolyte fuel cells (PEFCs) consist of a thin film of highly inter-mixed ionomer and catalyst that is applied to the electrolyte membrane. High performances are achieved with loadings as low as 0.12 mg Pt cm?2 at the cathode and even lower loadings are required at the anode. However, the long-term performance of these

  8. Evaluation of the economic feasibility of core-shell baroplastic polymers and a comparison to traditional thermoplastic elastomers

    E-print Network

    Ibrahim, Sarah H

    2005-01-01

    Baroplastic materials are pressure miscible systems that can be molded by the application of pressure at low/room temperature. They have the potential to replace traditional thermoplastic elastomers in many applications. ...

  9. A thermoplastic polyimidesulfone

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.; Yamaki, D. A.

    1982-01-01

    A polymer system has been prepared which has the excellent thermoplastic properties generally associated with polysulfones, and the solvent resistance and thermal stability of aromatic polyimides. This material, with improved processability over the base polyimide, can be processed in the 260-325 C range in such a manner as to yield high quality, tough unfilled moldings; strong, high-temperature-resistant adhesive bonds; and well consolidated, graphite-fiber-reinforced moldings (composities). The unfilled moldings have physical properties that are similar to aromatic polysulfones which demonstrates the potential as an engineering thermoplastic. The adhesive bonds exhibit excellent retention of initial strength levels even after thermal aging for 5000 hours at 232 C. The graphite-fiber-reinforced moldings have mechanical properties which makes this polymer attractive for the fabrication of structural composites.

  10. Measurements of temperature during fatigue of a thermoplastic polymer composite using FBG sensors

    NASA Astrophysics Data System (ADS)

    Facchini, M.; Botsis, J.; Sorensen, L.

    2007-04-01

    It is well known that cyclic fatigue induces hysteretic heating and temperature increase in polymer composite materials. Optical sensing technology is well developed to perform efficient in-field monitoring of the thermo-mechanical behaviour of engineering composite structures in sectors ranging from automotive to aerospace, where the implications of thermal fatigue are important. In this paper an experimental method and its results for temperature measurements in a glass/polypropylene composite beam subjected to cyclic bending at 6 Hz are reported. Since the sensors are sensitive to both temperature and strain, they are placed on the surface and in the centre of the specimen during processing, thus minimizing the effects of the mechanical strain during loading. Temperature increases of 9 °C both inside and on the specimen surface are recorded with fibre Bragg grating (FBG) sensors and verified by full-field temperature analysis using infrared thermography on the surface and thermocouples on both the surface and through the thickness of the composite. Discrimination between relatively large dynamic strain (responsible for ~280 pm Bragg wavelength shift oscillations), birefringence (responsible for ~70 pm), and temperature variations (9 °C leads to a Bragg wavelength shift of ~240 pm) is achieved by suitable integration of embedded FBGs and optical data processing. The achieved temperature resolution is 1 °C. The method outlined in this paper can be applied in various experimental configurations for temperature measurements in polymeric materials.

  11. A Solvent-Resistant, Thermoplastic Poly(imidesulfone)

    NASA Technical Reports Server (NTRS)

    St. Clair, T. L.; Yamaki, D.

    1983-01-01

    Process for preparing thermoplastic poly(imidesulfone) results in material having excellent thermoplastic properties generally associated with polysulfones and excellent solvent resistance generally associated with polyimides. New thermoplastic, solvent-resistant polymer is used as molding resin, as adhesive, and as matrix resin for fiber reinforced composites.

  12. Noncollinear wave mixing for measurement of dynamic processes in polymers: Physical ageing in thermoplastics and epoxy cure

    E-print Network

    Korneev, Valeri A.

    in thermoplastics and epoxy cure A. Demcenko a, , V. Koissin a , V.A. Korneev b a Faculty of Engineering Technology-linear ultrasonics Physical ageing Epoxy cure Rheometry a b s t r a c t Elastic wave mixing using an immersion method curing, and non-destructive testing. In water, excita- tion and reception of waves do not require

  13. ABA Type Triblock Copolymer Based on Mesogen-Jacketed Liquid Crystalline Polymer: Design, Synthesis, and Potential as Thermoplastic

    E-print Network

    Wan, Xin-hua

    are elastomeric. Preliminary mechanical tests were done on their films. Typical dynamic mechanical analysis by nuclear magnetic resonance. Curves of differential scanning calorimetry indicate the immiscibility and tensile tests prove that the sample has the potential as thermoplastic elastomers (TPEs). According to our

  14. An overview of long fiber reinforced thermoplastics

    SciTech Connect

    Bockstedt, R.J.; Skarlupka, R.J. [Polymer Composites Inc., Winona, MN (United States)

    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.

  15. The Application of Di-isocyante Modified Agro-polymer as Filler For XNBR\\/PA12 Thermoplastic Elastomer Composites

    Microsoft Academic Search

    Ahmad Mousa; Gert Heinrich; Udo Wagenknecht; Bernd Kretzschmar; Maria Auf der Landwehr

    2012-01-01

    Lignocelluloses industrial waste flour of olive husk powder (LCF) was utilized as reinforcement in carboxylated nitrile butadiene rubber (XNBR)\\/Polyamide-12 (PA-12) thermoplastic elastomer composites. To improve the bonding quality between the LCF and the blend, the powder was chemically treated by two means, the former is the treatment with toulene-2–4-diisocyanate (TDIC), and the latter is mercerization with sodium hydroxide followed by

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  17. Aerogel/polymer composite materials

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

    2010-01-01

    The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

  18. Surface characterization in composite and titanium bonding: Carbon fiber surface treatments for improved adhesion to thermoplastic polymers

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    The effect of anodization in NaOH, H2SO4, and amine salts on the surface chemistry of carbon fibers was examined by X-ray photoelectron spectroscopy (XPS). The surfaces of carbon fibers after anodization in NaOH and H2SO4 were examined by scanning transmission electron microscopy (STEM), angular dependent XPS, UV absorption spectroscopy of the anodization bath, secondary ion mass spectrometry, and polar/dispersive surface energy analysis. Hercules AS-4, Dexter Hysol XAS, and Union Carbide T-300 fibers were examined by STEM, angular dependent XPS, and breaking strength measurement before and after commercial surface treatment. Oxygen and nitrogen were added to the fiber surfaces by anodization in amine salts. Analysis of the plasmon peak in the carbon 1s signal indicated that H2SO4 anodization affected the morphological structure of the carbon fiber surface. The work of adhesion of carbon fibers to thermoplastic resins was calculated using the geometric mean relationship. A correlation was observed between the dispersive component of the work of adhesion and the interfacial adhesion.

  19. Thermoplastic polyurethane/hydroxyapatite electrospun scaffolds for bone tissue engineering: effects of polymer properties and particle size.

    PubMed

    Mi, Hao-Yang; Palumbo, SunMi; Jing, Xin; Turng, Lih-Sheng; Li, Wan-Ju; Peng, Xiang-Fang

    2014-10-01

    Thermoplastic polyurethane (TPU)/hydroxyapatite (HA) scaffolds were fabricated via electrospinning. The effects of TPU properties and HA particle size on scaffold physical properties and osteoblast-like cell performance were investigated. It was found that the addition of micro-HA (mHA), which was inlayed in the fiber, decreased the electrospun fiber diameter. On the contrary, nano-HA (nHA), which was either embedded or existed inside of the fiber, increased the fiber diameter for both soft and hard TPUs. The soft TPU had a much lower Young's modulus and higher strain-at-break than the hard TPU. The addition of both mHA and nHA decreased the tensile properties; this decrease was more significant with mHA. The cells on the hard scaffolds actively proliferated and migrated compared to those on the soft scaffolds. On the other hand, cells on the soft scaffolds more effectively induced osteogenesis of human mesenchymal stem cells (hMSCs) than those on the hard scaffolds. In addition, our data suggest that the soft scaffolds with supplementation of nHA further enhanced osteogenesis of hMSCs compared to those without nHA. The soft TPU scaffolds containing nano-HA have the potential to be used in bone tissue engineering applications. PMID:24574168

  20. Noncollinear wave mixing for measurement of dynamic processes in polymers: physical ageing in thermoplastics and epoxy cure.

    PubMed

    Dem?enko, A; Koissin, V; Korneev, V A

    2014-02-01

    Elastic wave mixing using an immersion method has shown effective monitoring and scanning capabilities when applied to thermoplastic ageing, epoxy curing, and non-destructive testing. In water, excitation and reception of waves do not require physical contact between the tools and the specimen, making the acquisition of high-resolution C-scans possible. The nonlinear material parameters exhibit a much higher sensitivity to the specimen state compared to linear ones. Thus, the nonlinear data for polymethyl methacrylate (PMMA) have a 40% difference between zones of "young" and "aged" material, while the linear data show no difference at all. Methodology and logistics of the immersion wave-mixing method are discussed in detail. Monitoring of epoxy curing has also revealed a good sensitivity of the method to this complex process including several characteristic stages, such as the time of maximal viscosity, the gel time, and the vitrification time. These stages are independently verified in separate rheometry measurements. The presented method allows for a number of possibilities: wave-mode and frequency separations, elimination of surrounding medium influence, "steering" (scanning) a scattered wave, controlling the location of the intersection volume, single-sided or double-sided measurements, and operation in detector mode. PMID:24094687

  1. 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.

  2. Evaluation of the thermoplasticity of different gutta-percha cones and Resilon ?

    Microsoft Academic Search

    Mário Tanomaru-Filho; Geraldine Faccio Silveira; Juliane Maria Guerreiro Tanomaru; Carlos Alexandre Souza Bier

    2007-01-01

    The goal of this study was to evaluate the thermoplasticity of conventional and thermoplastic gutta-percha and Resilon ® , a polyester polymer-based material. Specimens with standardised dimensions were made from the following mate- rials: conventional and thermoplastic gutta-percha (Dentsply), conventional and thermoplastic gutta-percha (Endopoints) and Resilon ® . After 24 h, the specimens were placed in water at 70°C for

  3. An overview of long fiber reinforced thermoplastics

    SciTech Connect

    Bockstedt R.J.; Skarlupka, R.J. [Polymer Composites Inc., Winona, MN (United States)

    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.

  4. 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.

  5. Poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene) conjugated polymer domains in a thermoplastic polyurethane matrix

    NASA Astrophysics Data System (ADS)

    Patrício, Patrícia S. O.; Silva, Glaura G.; de Oliveira, Flávio A. C.; Righi, Ariete; Neves, Bernardo R. A.; Cury, Luiz A.

    2007-02-01

    Self-sustained and spin-casting films formed from blends of poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH-PPV) conjugated polymer and thermoplastic poly-urethane (TPU) at different concentrations have been investigated. Scanning electron microscopy images of self-sustained films show the formation of circularlike domains of MEH-PPV in the TPU matrix, characterizing the blend material as heterogeneous. The circularlike domains in the spin-casting films were also observed by electric force microscopy (EFM) and by atomic force microscopy. The EFM, in particular, has allowed the differentiation of the MEH-PPV domains from the TPU matrix due to the electrical properties of the conjugated polymer. The MEH-PPV domains in the spin-casting films are much smaller in size than in the case of self-sustained films. The glass transition temperatures for the TPU and for the self-sustained blended films were obtained by temperature modulated differential scanning calorimetry. A very small variation in the glass transition temperature (Tg) has been observed for the blends. This fact further corroborates that MEH-PPV and TPU form immiscible blends. Intermolecular interactions between the MEH-PPV and the TPU materials were proposed to occur at the interfaces of the domains. These interfacial interactions have not affected the Raman modes, which pointed out that they are relatively weak interactions. The formation of small conjugation segments of the MEH-PPV molecules due to these interfacial interactions with the TPU molecules at the interfaces of the domains was assigned to be responsible by the appearance of a large tail and clear shoulders to the high energy side of the photoluminescence (PL) spectra of self-sustained samples. This was also assigned to be responsible by the blueshift observed in the PL spectra of spin-casting films. The redshift of the pure electronic transition peak and the first vibronic band (which presents an inhomogeneous broadening) were observed in the self-sustained blended films and were related, respectively, to the increase of the internal intermolecular and intramolecular interactions due to the conformational disorder of the MEH-PPV molecules imposed by the casting spread technique.

  6. 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.

  7. 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.

  8. In situ Formation of Thermoplastic Composites: Ultem\\/Vectra

    Microsoft Academic Search

    T. Sun; D. G. Baird; H. H. Huang; D. S. Done; G. L. Wilkes

    1991-01-01

    This paper is concerned with the development of films of an engineering thermoplastic, polyetherimide (Ultem), reinforced with a thermotropic liquid crystalline polymer (Vectra). In particular the processing conditions for which fibrils of Vectra can be formed are established. The upper processing temperature is established by the point at which the polymers degrade while the lower is that at which G‘

  9. An investigation of physical properties of thermoplastic polyimides

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Stoakley, Diane M.

    1987-01-01

    Thermoplastic polyimides are a class of promising high temperature polymers for aerospace applications. NASA-developed LARC-TPI is a prominent member of this family of polymers. Its physical characteristics have been measured as a function of its curing schedule. The results and their possible interpretations are discussed.

  10. 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.

  11. Processing of wood-thermoplastic composites

    Microsoft Academic Search

    Mladen Šercer; Pero Raos; Maja Rujni?-Sokele

    2009-01-01

    Natural and wood fibre plastic composites (WPC) are among the most rapidly growing markets within the plastics industry. They\\u000a are manufactured by combining either wood or other natural fibers such as flax, hemp, jute or kenaf with polymers. Thermoplastic\\u000a resins, such as polypropylene, polyethylene or polystyrene, are mixed with other materials (such as wood), and form a composite\\u000a product. The

  12. 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.

  13. 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, Miros?awa; 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. PMID:20034664

  14. 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.

  15. Ultrasoft Thermoplastic Polyurethanes This work evolved from collaboration between my laboratory and CPT Industries, Inc. I

    E-print Network

    Harmon, Julie P.

    ) thermoplastic poly(carbonate urethane)s that do not exhibit surface tackiness. These novel polyurethanes target growing markets for biocompatible polymers used in peristaltic pump tubing, balloon catheters, enteral

  16. Plane stretching of thermoplastics

    Microsoft Academic Search

    V. N. Sapozhnikov

    1965-01-01

    Plane stretching tests over a wide temperature interval have been used to construct moldability curves for several thermoplastic resins produced in the USSR. These curves are found to have two maxima in the temperature range studied. The effect of the strain rate, heterogeneity of the material, and the addition of fillers, plasticizers, and cross-linking agents upon the formation of these

  17. Thermoplastics Reinforced with Wood Fillers: A Literature Review

    Microsoft Academic Search

    A. K. BLEDZKI; S. REIHMANE; J. GASSAN

    1998-01-01

    Problems concerning the processing of thermoplastics reinforced with wood fillers are discussed. The high level of moisture absorption by the filler, its poor wettability, as well as the insufficient adhesion between untreated filler and the polymer matrix are reasons for the low tensile strength and high moisture sorption of composites. These shortcomings of composites can be prevented by the modification

  18. Preparation and characterization of magnetic thermoplastic-based nanocomposites

    NASA Astrophysics Data System (ADS)

    Thu, T. V.; Takamura, T.; Tsetserukou, D.; Sandhu, A.

    2014-02-01

    We developed a facile method for the preparation of magnetic nanocomposites based on the popular thermoplastic, acrylonitrile butadiene styrene (ABS). The nanocomposites were produced by liquid blending of ABS and Ni nanorods (NRs), followed by solvent evaporation. The characterizations showed that the nanocomposites were magnetic and Ni NRs were uniformly distributed in polymer matrix.

  19. Morphological, mechanical properties and biodegradability of biocomposite thermoplastic starch and polycaprolactone reinforced with sisal fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The incorporation of fibers as reinforcements in polymer composites has increased due to their renewability, low cost and biodegradability. In this study, sisal fibers were added to a polymer matrix of thermoplastic starch and polycaprolactone, both biodegradable polymers. Sisal fibers (5% and 10%) ...

  20. Thermal analysis of joining thermoplastic composites using microwaves

    Microsoft Academic Search

    H S Ku; K F Lee

    Industrial microwave technology for processing polymers and polymer-based composites is currently in a state of considerable flux. Ku et al. (1997a; 1997b; 1999a) used the equipment shown in Figure 1 to join random glass or carbon fibres reinforced thermoplastic composites. The material used for the research is 33% by weight random glass fibre reinforced low-density polyethylene (LDPE\\/GF (33%)) using Araldite

  1. 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.

  2. 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.

  3. The quality of fibre reinforced thermoplastics mouldings

    NASA Astrophysics Data System (ADS)

    Potts, Hugh Adrian

    The requirement for injection molded short carbon fiber reinforced thermoplastics in helicopter applications is based on component coat and weight savings. The presence of short fibers in a thermoplastic polymer can exert a significant influence upon the rheological properties of the melt. As it is the rheology of the material which determines melt flow performance and hence the flow-induced fiber orientation in the final molded part, accurate data are required to understand and predict polymer flow. Although standard procedures exist for determining the rheological characteristics of melts, their relevance to the injection modling proscess was questioned. Consequently, a high shear rate rheometer was developed, and the results for the filled and unfilled melts compared with the standard equipment. Significant effects involving thermal conductivity and fiber breaking were identified which leads to errors in the data produced using the standard device. Two techniques using reflected light and thermal imaging were successfully developed for the characterization of the orientation of short carbon fibers in injection molded parts. Welds are a common feature in injection molded parts. This study also addresses the problem of the knit weld in a specially designed test specimen. Applying fracture mechanics principles, the integrity of the welded structure was analyzed, and the results correlated with microstructural observations. Finally, impact studied using subcomponent geometries have addressed the effects of flow induced fiber orientation in specific geometrical features.

  4. 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.

  5. 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.

  6. Phase Separation of Liquid Crystals in Polymers

    Microsoft Academic Search

    John L. West

    1988-01-01

    New optoelectronic materials based on polymer dispersed liquid crystals (PDLC) show great potential for application in displays, temperature sensors, optical computing and for solar energy control. We report liquid crystal, termoset or thermoplastic materials. PDLC materials may be formed by several different processes. The liquid crystal may be dissolved in low molecular weight polymer precursors, in a thermoplastic melt or

  7. Close Encounters of the Polymer Kind

    NSDL National Science Digital Library

    National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

    Polymers are a vital part of our everyday lives and nearly all consumer products have a plastic component of some variation. Students explore the basic characteristics of polymers through the introduction of two polymer categories: thermoplastics and thermosets. During teacher demos, students observe the unique behaviors of thermoplastics. The fundamentals of thermoset polymers are discussed, preparing them to conduct the associated activity in which they create their own thermoset materials and mechanically test them. At the conclusion of this lesson-activity pair, students understand the basics of thermoplastics and thermosets, which may entice their interest in polymer engineering.

  8. Thermoplastic bonding of microfluidic substrates

    E-print Network

    Judge, Benjamin Michael

    2012-01-01

    The assembly of microfluidic components for lab on a chip (LOC) applications that are manufactured from commodity thermoplastics is challenging. A survey of plastic welding techniques validates that contour transmission ...

  9. 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.

  10. 3-D stamp forming of thermoplastic matrix composites

    Microsoft Academic Search

    M. Hou; K. Friedrich

    1994-01-01

    In this investigation a mould with hemispherical cavity and 80 kN hydraulic press, allowing variable stamping speeds, are employed for experimentally studying of the 3-D stamp forming process of continuous fiber reinforced thermoplastic laminates. In particular, glass fiber (GF) reinforced polyetherimide (PEI) woven fabric made of sheath surrounded, polymer powder impregnated fiber bundles manufactured by Enichem, Italy, is used. Pre-consolidated

  11. 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.

  12. Mechanical properties of green composites based on thermoplastic starch

    NASA Astrophysics Data System (ADS)

    Fornes, F.; Sánchez-Nácher, L.; Fenollar, O.; Boronat, T.; Garcia-Sanoguera, D.

    2010-06-01

    The present work is focused on study of "green composites" elaborated from thermoplastic starch (TPS) as polymer matrix and a fiber from natural origin (rush) as reinforced fiber. The effect of the fiber content has been studied by means of the mechanical properties. The composite resulting presents a lack of interaction between matrix and fiber that represents a performance decrease. However the biodegradability behavior of the resulting composite raise this composite as useful an industrial level.

  13. Low temperature properties of engineering thermoplastics

    SciTech Connect

    Kaye, C.J.

    1991-01-01

    There are currently a wide variety of engineering thermoplastics available for a multitude of applications. Because of present market requirements, there has been a limited demand for test results of the physical properties of these materials at low temperatures. Several potential applications exist, however, and as a result, several engineering thermoplastic samples were tested at {minus}40 and {minus}56.6{degrees}C. Although not all these tests followed the procedures specified by the American Society of Testing and Materials precisely, the data represent comparative data that can be utilized for further design efforts. The evaluations included tensile testing, compressive properties, and Izod impact testing. Several materials with varied glass loadings were studied to determine the low temperature tendencies these molding compounds would exhibit. Some of the resins examined were: polyetheretherketone (PEEK), polytherimide (PEI), polyphenylene sulfide (PPS), polyethersulfone (PES), polyphthlamide (PPA), and a liquid crystal polymer (Vectra A130). In all cases, no detrimental effect was discerned over this temperature range; the study also indicated that improvements in the physical properties could be expected.

  14. 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.

  15. 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.

  16. Opportunities with thermoplastics.

    PubMed

    Vaahs, Tilo

    2003-04-01

    Whether as substitutes for glass and metal, or completely novel injection moulded applications, engineering polymers offer a range of opportunities for developing cost-effective, safe and smart medical devices. PMID:12789700

  17. Thermoplastic tape compaction device

    DOEpatents

    Campbell, Vincent W. (Oak Ridge, TN)

    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.

  18. 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.

  19. 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.

  20. 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.

  1. Reinforcing of thermoplastic polycarbonate and polysulfone with carbon fibers: Production and characteristics of UD-compound objects

    NASA Technical Reports Server (NTRS)

    Fitzer, E.; Jaeger, H.

    1988-01-01

    The production and characteristics of the carbon fiber reinforced thermoplastics polycarbonate and polysulfone are described. The production of prepregs from defined polymer solutions is emphasized along with methods of optimizing the production of compounds. The characteristics of unidirectionally reinforced thermoplastics, such as shear strength, bending strength, and impact resistance are compared with regard to fracture behavior, the influence of intermediate layers, and the behavior under cryogenic conditions and under slightly elevated temperatures. The problem of adhesion between high strength carbon fibers and thermoplastics is examined, taking into account the effect of moisture on the shear strength and the impact resistance.

  2. 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.

  3. Polymers Are Everywhere.

    ERIC Educational Resources Information Center

    Seymour, Raymond B.

    1988-01-01

    Describes the history of the human understanding of polymers from alchemy to modern times. Discusses renaissance chemistry, polymers in the nineteenth century, synthetic elastomers, thermoplastic elastomers, fibers, coatings, adhesives, derivatives of natural rubber, thermosets, step-reaction, and chain polymerization. (CW)

  4. The micromorphology of an injection moulded thermotropic liquid crystal polymer

    Microsoft Academic Search

    H. Thapar; M. Bevis

    1983-01-01

    The authors are presently engaged in an investigation of the relationship between the processing conditions, micromorphology and the physical properties of injection moulded thermotropic liquid crystal polymers, which as potential selfreinforcing thermoplastics are expected to provide alte.rnatives to glass fibre-reinforced thermoplastics [1]. The liquid crystal polymer used to gain the results reported in this letter was prepared by ICI Plastics

  5. Recycled Thermoplastic–Woodflour Composites

    Microsoft Academic Search

    D. Maldas; B. V. Kokta

    1994-01-01

    In the present study, composite materials were prepared from recycled PE, PP and commingled plastics, and waste cellulosics, e.g., sawdust (woodflour) of maple wood. In order to establish the compatibility, the woodflour was surface modified by precoating with maleated thermoplastics. Moreover, to improve the fire-retardancy, and at the same time to minimize the degradation of recycled plastics and woodflour various

  6. Fully integrated single-walled carbon nanotube thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Rodriguez-Macias, Fernando J.

    The development of composites of single-walled carbon nanotubes (SWNTs) with thermoplastics requires methods for good dispersion and achieving good interaction between SWNTs and the matrix. This thesis presents a new method to achieve good dispersion by a preliminary treatment called incipient wetting. The SWNTs dispersed in a solvent are mixed with polymer particles and deposited over them as the solvent is evaporated to give an initial dispersion. Factors that make this more effective are: good wetting of the polymer by the solvent, swelling of the polymer, high surface area of the polymer. Swelling enhances the initial dispersion with some initial mixing. A high surface area is achieved using polymer powder. High shear mixing alone does not achieve the same uniform and repeatable level of dispersion that the combination with incipient wetting allows. The incipient wetting method was studied and applied to different polymers. The possibility of recovering SWNTs from thermoplastics by dissolving or burning away the matrix is an extension of this study. A new comprehensive approach to control the interface of thermoplastics with SWNTs is studied. This is based on achieving direct chemical bonding between polymer molecules and functional groups on oxidized open ends, sidewalls, or both, in the SWNTs. Different concepts and approaches to these "fully integrated nanotube composites" are discussed. The concepts have been applied to epoxies elsewhere and are tested here with nylon-6,6 as a model system. Nylon was synthesized by interfacial polymerization in the presence of SWNTs resulting in excellent dispersion in the composite without further processing. The essential requirement for good dispersion is that the SWNTs are well dispersed in the solvent. Interfacial polymerization opens the way to many types of polymer-SWNT composites. Tests of full integration of SWNTs with open ended nanotubes showed promising results and hints of integration but were limited by dispersion in the solvent. Fluorinated SWNTs were dispersed effectively with dichlorobenzene, another solvent may be better. There is no conclusive evidence of integration with F-SWNTs but they may react with the polymer chain with thermal post-processing.

  7. Design and development of thermoplastic composite manufacturing processes based on electrostatic powder spray impregnation

    Microsoft Academic Search

    Mark Stephen Duvall

    1998-01-01

    This research encompasses the design and development of a versatile thermoplastic composite manufacturing process. This process was specifically designed to include all the stages of a complete composite manufacturing process, from the initial combination of the resin and fiber materials to the final part consolidation. A detailed apparatus was designed to spread continuous fibers, coat them with electrostatically charged polymer

  8. Valveless diffuser micropumps fabricated using thermoplastic replication

    Microsoft Academic Search

    Anders Olsson; Olle Larsson; Johan Holm; Lars Lundbladh; Ove Öhman; Göran Stemme

    1998-01-01

    This paper presents valve-less diffuser micropumps fabricated using thermoplastic replication. Thermoplastic replication is very suitable for a valve-less diffuser pump due to its simple planar geometry. Two different thermoplastic replication methods have been tested: hot embossing and injection molding. We use 0.1 and 0.2 mm deep precision-milled brass mold inserts and 20 and 80 ?m deep microelectroformed nickel mold inserts

  9. Characterization of a thermoplastic polyimidesulfone

    NASA Technical Reports Server (NTRS)

    Dezern, J. F.; Young, P. R.

    1985-01-01

    The detailed characterization of an experimental thermoplastic polyimidesulfone adhesive based on 3,3 prime-diaminodiphenylsulfone and 3,3 prime,4,4 prime-benzophenone tetracarboxylic dianhydride was studied. Model compounds were also examined. Thermal cyclization of the amide-acid to the imide was studied by a variety of techniques including DSC, TGA, MS, in situ diffuse reflectance-FTIR, and flow mearsurement. Characterizations were continued during the processing of adhesive tapes and the fabrication, bonding, and testing of lap shear specimens. Results provide fundamental insights into the role of cure chemistry, and the effects of residual solvent and volatile produces on processing and performance. These insights and the resulting chemical models should lead to more efficient processing cycles for these and other related thermoplastic adhesive systems.

  10. 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.

  11. Portable Device Slices Thermoplastic Prepregs

    NASA Technical Reports Server (NTRS)

    Taylor, Beverly A.; Boston, Morton W.; Wilson, Maywood L.

    1993-01-01

    Prepreg slitter designed to slit various widths rapidly by use of slicing bar holding several blades, each capable of slicing strip of preset width in single pass. Produces material evenly sliced and does not contain jagged edges. Used for various applications in such batch processes involving composite materials as press molding and autoclaving, and in such continuous processes as pultrusion. Useful to all manufacturers of thermoplastic composites, and in slicing B-staged thermoset composites.

  12. Final Report: Interphase Analysis and Control in Fiber Reinforced Thermoplastic Composites

    SciTech Connect

    Jon J. Kellar; William M. Cross; Lidvin Kjerengtroen

    2009-03-14

    This research program builds upon a multi-disciplinary effort in interphase analysis and control in thermoplastic matrix polymer matrix composites (PMC). The research investigates model systems deemed of interest by members of the Automotive Composites Consortium (ACC) as well as samples at the forefront of PMC process development (DRIFT and P4 technologies). Finally, the research investigates, based upon the fundamental understanding of the interphases created during the fabrication of thermoplastic PMCs, the role the interphase play in key bulk properties of interest to the automotive industry.

  13. Determination of adhesion between thermoplastic and liquid silicone rubbers in hard-soft-combinations via mechanical peeling test

    NASA Astrophysics Data System (ADS)

    Kühr, C.; Spörrer, A.; Altstädt, V.

    2014-05-01

    The production of hard-soft-combinations via multi injection molding gained more and more importance in the last years. This is attributed to different factors. One principle reason is that the use of two-component injection molding technique has many advantages such as cancelling subsequent and complex steps and shortening the process chain. Furthermore this technique allows the combination of the properties of the single components like the high stiffness of the hard component and the elastic properties of the soft component. Because of the incompatibility of some polymers the adhesion on the interface has to be determined. Thereby adhesion is not only influenced by the applied polymers, but also by the injection molding parameters and the characteristics of the mold. Besides already known combinations of thermoplastics with thermoplastic elastomers (TPE), there consists the possibility to apply liquid silicone rubber (LSR) as soft component. A thermoplastic/LSR combination gains in importance due to the specific advantages of LSR to TPE. The faintly adhesion between LSR and thermoplastics is currently one of the key challenges when dealing with those combinations. So it is coercively necessary to improve adhesion between the two components by adding an adhesion promoter. To determine the promoters influence, it is necessary to develop a suitable testing method to investigate e.g. the peel resistance. The current German standard "VDI Richtlinie 2019', which is actually only employed for thermoplastic/TPE combinations, can serve as a model to determine the adhesion of thermoplastic/LSR combinations.

  14. Synthesis and characterization of novel thermoplastic elastomers incorporating tailored temperature switching hard blocks

    SciTech Connect

    Bitler, S.P.; Kamp. D.A.; Yoon V.Y. [Landec Corp., Menlo Park, CA (United States)

    1993-12-31

    This paper reports the synthesis and characterization of a novel class of thermoplastics elastomers (TPEs) that exhibit a unique temperature switching property that is variable over a broad temperature range due to the choice of hard block components. The hard blocks are crystalline polymers or oligomers from a family known as side chain crystalline (SCC) polymers, referred as the Intelimers{sup R} at Landec Corporation when thermal transitions are accurately controlled over the technique range of 0 to 100-{degrees}c. Attachment of these SCC polymer or oligomers to soft or low Tg noncrystalline blocks results in thermoplastic elastomers where the macroscopic viscous flow property can be accurately switched from a rubbery two phase solid to a viscous fluid at a controlled specific temperature. Rheological evaluations show a dramatic complex modulus decrease within 10{degrees}C of the DSC endotherm peak. Physical and mechanical properties of the TPEs were evaluated with calcium carbonate filler.

  15. Study on the Functionality of Nano-Precipitated Calcium Carbonate as Filler in Thermoplastics

    NASA Astrophysics Data System (ADS)

    Basilia, Blessie A.; Panganiban, Marian Elaine G.; Collado, Archilles Allen V. C.; Pesigan, Michael Oliver D.; de Yro, Persia Ada

    This research aims to investigate the functionality of nano-precipitated calcium carbonate (NPCC) as filler in thermoplastic resins based on property enhancement. Three types of thermoplastics were used: polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC). The resins were evaluated by determining the effect of different NPCC loading on the chemical structure, thermal and mechanical properties of thermoplastics. Results showed that there was an interfacial bonding with the NPCC surface and the thermoplastics. Change in absorption peak and area were predominant in the PVC filled composite. There was a decreased in crystallinity of the PE and PP with the addition of filler. Tremendous increase on the tensile and impact strength was exhibited by the NPCC filled PVC composites while PE and PP composites maintained a slight increase in their mechanical properties. Nano-sized filler was proven to improve the mechanical properties of thermoplastics compared with micron-sized filler because nano-sized filler has larger interfacial area between the filler and the polymer matrix.

  16. Improved construction materials for polar regions using microcellular thermoplastic foams

    NASA Technical Reports Server (NTRS)

    Cunningham, Daniel J.

    1994-01-01

    Microcellular polymer foams (MCF) are thermoplastic foams with very small cell diameters, less than 10 microns, and very large cell densities, 10(exp 9) to 10(exp 15) cells per cubic centimeter of unfoamed material. The concept of foaming polymers with microcellular voids was conceived to reduce the amount of material used for mass-produced items without compromising the mechanical properties. The reasoning behind this concept was that if voids smaller than the critical flaw size pre-existing in polymers were introduced into the matrix, they would not affect the overall strength of the product. MCF polycarbonate (PC), polystyrene (PS), and polyvinyl chloride (PVC) were examined to determine the effects of the microstructure towards the mechanical properties of the materials at room and arctic temperatures. Batch process parameters were discovered for these materials and foamed samples of three densities were produced for each material. To quantify the toughness and strength of these polymers, the tensile yield strength, tensile toughness, and impact resistance were measured at room and arctic temperatures. The feasibility of MCF polymers has been demonstrated by the consistent and repeatable MCF microstructures formed, but the improvements in the mechanical properties were not conclusive. Therefore the usefulness of the MCF polymers to replace other materials in arctic environments is questionable.

  17. 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.

  18. 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. PMID:18838261

  19. 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 the pores in the specimens. The maximum relative permeabilities of cores made without annealing ranged from 30 to 110, while those of cores made with annealing ranged from 900 to 1,400. However, the greater permeabilities of the annealed specimens were not associated with noticeably greater densities. The major practical result of the investigation was the discovery of an optimum distribution of iron-particle sizes: It was found that eddy-current losses in the molded cores were minimized by using 100 mesh (corresponding to particles with diameters less than or equal to 100 m) iron particles. The effect of optimization of particle sizes on eddy-current losses is depicted in the figure.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  1. 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

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

    PubMed

    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

  3. Joining of thermoplastic substrates by microwaves

    DOEpatents

    Paulauskas, Felix L. (Oak Ridge, TN); Meek, Thomas T. (Knoxville, TN)

    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.

  4. 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 abundant active epoxy groups on surfaces were fabricated through above technique. The prepared PE-co-GMA nanofibers were aminated by reacting the epoxy groups with 1,3-diaminopropane. The resulting aminated PE-co-GMA nanofibers were subsequently biotinylated and then successfully applied to immobilize streptavidin-horseradish peroxidase (HRP) conjugate via specific, strong and rapid binding of biotin and streptavidin. The high activity, efficiency, sensitivity as well as good reusability of the streptavidin-HRP immobilized PE-co-GMA nanofibers demonstrated that PE-co-GMA nanofibers could be a promising candidate as solid support materials for potential biosensor applications.

  5. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  6. Process for preparing thermoplastic aromatic polyimides

    NASA Technical Reports Server (NTRS)

    Bell, V. L. (inventor)

    1978-01-01

    A method of preparing insoluble thermoplastic aromatic polyimides is described, having uniquely low softening temperatures by reacting, in a suitable solvent, an aromatic dianhydride, and a meta-substituted aromatic diamine.

  7. 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.

  8. 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.

  9. Graphene-polymer composites

    NASA Astrophysics Data System (ADS)

    Carotenuto, G.; Romeo, V.; Cannavaro, I.; Roncato, D.; Martorana, B.; Gosso, M.

    2012-09-01

    Graphene is a novel nanostructured material that can be conveniently used as filler for thermoplastic polymers or thermosetting resins, and the resulting nanocomposite material has unique mechanical and chemical/physical properties. Industrial production of graphene/polymer materials requires the availability of a chemical route to produce massive amount of graphene. Natural graphite flakes can be the best starting material for a bulk-production of graphene to be used in the polymeric nanocomposite preparation.

  10. Modelling laser light propagation in thermoplastics using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Parkinson, Alexander

    Laser welding has great potential as a fast, non-contact joining method for thermoplastic parts. In the laser transmission welding of thermoplastics, light passes through a semi-transparent part to reach the weld interface. There, it is absorbed as heat, which causes melting and subsequent welding. The distribution and quantity of light reaching the interface are important for predicting the quality of a weld, but are experimentally difficult to estimate. A model for simulating the path of this laser light through these light-scattering plastic parts has been developed. The technique uses a Monte-Carlo approach to generate photon paths through the material, accounting for absorption, scattering and reflection between boundaries in the transparent polymer. It was assumed that any light escaping the bottom surface contributed to welding. The photon paths are then scaled according to the input beam profile in order to simulate non-Gaussian beam profiles. A method for determining the 3 independent optical parameters to accurately predict transmission and beam power distribution at the interface was established using experimental data for polycarbonate at 4 different glass fibre concentrations and polyamide-6 reinforced with 20% long glass fibres. Exit beam profiles and transmissions predicted by the simulation were found to be in generally good agreement (R2>0.90) with experimental measurements. The simulations allowed the prediction of transmission and power distributions at other thicknesses as well as information on reflection, energy absorption and power distributions at other thicknesses for these materials.

  11. Investigations on laser transmission welding of absorber-free thermoplastics

    NASA Astrophysics Data System (ADS)

    Mamuschkin, Viktor; Olowinsky, Alexander; Britten, Simon W.; Engelmann, Christoph

    2014-03-01

    Within the plastic industry laser transmission welding ranks among the most important joining techniques and opens up new application areas continuously. So far, a big disadvantage of the process was the fact that the joining partners need different optical properties. Since thermoplastics are transparent for the radiation of conventional beam sources (800- 1100 nm) the absorbance of one of the joining partners has to be enhanced by adding an infrared absorber (IR-absorber). Until recently, welding of absorber-free parts has not been possible. New diode lasers provide a broad variety of wavelengths which allows exploiting intrinsic absorption bands of thermoplastics. The use of a proper wavelength in combination with special optics enables laser welding of two optically identical polymer parts without absorbers which can be utilized in a large number of applications primarily in the medical and food industry, where the use of absorbers usually entails costly and time-consuming authorization processes. In this paper some aspects of the process are considered as the influence of the focal position, which is crucial when both joining partners have equal optical properties. After a theoretical consideration, an evaluation is carried out based on welding trials with polycarbonate (PC). Further aspects such as gap bridging capability and the influence of thickness of the upper joining partner are investigated as well.

  12. 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 finite element discretisation. This model depends on material parameters of the thermoplastic and details of tests undertaken to determine these and the results produced are given. Finally the computational model is applied for a thin sheet of commercially available thermoplastic starch material which is thermoformed into a specific mould. Numerical results of thickness and shape for this problem are given.

  13. Extraction, characterization of components, and potential thermoplastic applications of camelina meal grafted with vinyl monomers.

    PubMed

    Reddy, Narendra; Jin, Enqi; Chen, Lihong; Jiang, Xue; Yang, Yiqi

    2012-05-16

    Camelina meal contains oil, proteins, and carbohydrates that can be used to develop value-added bioproducts. In addition to containing valuable polymers, coproducts generated during the production of biofuels are inexpensive and renewable. Camelina is a preferred oilseed crop for biodiesel production because camelina is easier to grow and provides better yields. In this research, the components in camelina meal were extracted and studied for their composition, structure, and properties. The potential of using the camelina meal to develop thermoplastics was also studied by grafting various vinyl monomers. Oil (19%) extracted from camelina meal could be useful for food and fuel applications, and proteins and cellulose in camelina meal could be useful in the development of films, fibers, and thermoplastics. Thermoplastic films developed from grafted camelina meal had excellent wet tensile properties, unlike thermoplastics developed from other biopolymers. Camelina meal grafted with butylmethacrylate (BMA) had high dry and wet tensile strengths of 53.7 and 17.3 MPa, respectively. PMID:22540881

  14. Melting behavior of typical thermoplastic materials--an experimental and chemical kinetics study.

    PubMed

    Wang, Nan; Tu, Ran; Ma, Xin; Xie, Qiyuan; Jiang, Xi

    2013-11-15

    A medium-scale melting experiment rig was designed and constructed in this study. A detailed experimental study was conducted on the melting behavior and the chemical kinetic characteristics of three typical thermoplastic materials, including polypropylene (PP), polyethylene (PE) and polystyrene (PS). It is observed that the thermal decomposition of the thermoplastic materials mainly consists of three stages: the initial heating stage, the melting-dominated stage and the gasification-dominated stage. Melting of the materials examined takes place within a certain temperature range. The melting temperature of PS is the lowest, moreover, it takes the shortest time to be completely liquefied. To quantitatively represent the chemical kinetics, an nth-order reaction model was employed to interpret the thermal decomposition behavior of the materials. The calculated reaction order is largely in accordance with the small-scale thermal gravimetric analysis (TGA). The small difference between the results and TGA data suggests that there are some limitations in the small-scale experiments in simulating the behavior of thermoplastic materials in a thermal hazard. Therefore, investigating the thermal physical and chemical properties of the thermoplastic materials and their thermal hazard prevention in medium or large-scale experiments is necessary for the fire safety considerations of polymer materials. PMID:24007994

  15. Effect of halogenation on the shock properties of semicrystalline thermoplastics

    NASA Astrophysics Data System (ADS)

    Bourne, N. K.; Millett, J. C. F.; Brown, E. N.; Gray, G. T.

    2007-09-01

    The high-strain rate response of polymers is a subject that has gathered interest over recent years due to their increasing engineering importance, particularly in the transport industries. This work explores the effect of fluorination upon semicrystalline thermoplastics. Polyethylene, with its simple hydrocarbon chain, is considered; with increasing fluorination of the carbon backbone polyvinylidene difluoride, and then polytetrafluorethylene (PTFE) is also compared. All three show a nonlinear equation of state behavior, which may be related to partial crystallinity. PTFE is shown to have anomalous release speed, which reflects its transformation from phase II to phase III transition at 0.7 GPa. Strength effects show a different ordering of behavior between the three materials. The first results are accountable purely using van der Waals forces between the chains. However, strength effects show the effect of further attractive forces that indicate some tacticity in the material associated with the state behind the shock.

  16. Preparation and characterization of thermoplastic materials for invisible orthodontics.

    PubMed

    Zhang, Ning; Bai, Yuxing; Ding, Xuejia; Zhang, Yu

    2011-11-25

    PETG/PC/TPU polymer blend was prepared by mechanical blending. The mechanical properties of modified PETG/PC/TPU blend were characterized using a universal testing machine, and results were compared against two commercial thermoplastic products -Erkodur and Biolon. Blending modification improved the properties of PETG/PC/TPU. When blending ratio (wt%) was 70/10/20, PETG/PC/TPU exhibited optimal mechanical properties which exceeded those of Erkodur and Biolon. Tear strength was 50.23 MPa and elongation at break was 155.99%. Stress relaxation rate was 0.0136 N/s after 1 hour, which was significantly slower than Erkodur and Biolon (p<0.05). Water absorption rate was 0.57% after 2 weeks, which was significantly lower than Erkodur and Biolon (p<0.05). PMID:22123023

  17. 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.

  18. Carbon nanotubes in blends of polycaprolactone/thermoplastic starch.

    PubMed

    Taghizadeh, Ata; Favis, Basil D

    2013-10-15

    Despite the importance of polymer-polymer multiphase systems, very little work has been carried out on the preferred localization of solid inclusions in such multiphase systems. In this work, carbon nanotubes (CNT) are dispersed with polycaprolactone (PCL) and thermoplastic starch (TPS) at several CNT contents via a combined solution/twin-screw extrusion melt mixing method. A PCL/CNT masterbatch was first prepared and then blended with 20 wt% TPS. Transmission and scanning electron microscopy images reveal a CNT localization principally in the TPS phase and partly at the PCL/TPS interface, with no further change by annealing. This indicates a strong driving force for the CNTs toward TPS. Young's model predicts that the nanotubes should be located at the interface. X-ray photoelectron spectroscopy (XPS) of extracted CNTs quantitatively confirms an encapsulation by TPS and reveals a covalent bonding of CNTs with thermoplastic starch. It appears likely that the nanotubes migrate to the interface, react with TPS and then are subsequently drawn into the low viscosity TPS phase. In a low shear rate/low shear stress internal mixer the nanotubes are found both in the PCL phase and at the PCL/TPS interface and have not completed the transit to the TPS phase. This latter result indicates the importance of choosing appropriate processing conditions in order to minimize kinetic effects. The addition of CNTs to PCL results in an increase in the crystallization temperature and a decrease in the percent crystallinity confirming the heterogeneous nucleating effect of the nanotubes. Finally, DMA analysis reveals a dramatic decrease in the starch rich phase transition temperature (~26 °C), for the system with nanotubes located in the TPS phase. PMID:23987335

  19. Development of Lignin-Based Polyurethane Thermoplastics

    SciTech Connect

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

    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.

  20. Post polymerization cure shape memory polymers

    DOEpatents

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  1. Polymers

    NSDL National Science Digital Library

    This page contains two documents explaining ring and cross link polymers. The topic is covered at an advanced level in relation to nanotechnology and requires background knowledge in eight grade science. A powerpoint with illustrations and instructor guide (available as both a Microsoft Word Document and PDF) containing activities are included to aid in teaching this subject.

  2. Biopolymer-based thermoplastic mixture for producing solid biodegradable shaped bodies and its photo degradation stability

    NASA Astrophysics Data System (ADS)

    Sulong, Nurulsaidatulsyida; Rus, Anika Zafiah M.

    2013-12-01

    In recent years, biopolymers with controllable lifetimes have become increasingly important for many applications in the areas of agriculture, biomedical implants and drug release, forestry, wild life conservation and waste management. Natural oils are considered to be the most important class of renewable sources. They can be obtained from naturally occurring plants, such as sunflower, cotton, linseed and palm oil. In Malaysia, palm oil is an inexpensive and commodity material. Biopolymer produced from palm oil (Bio-VOP) is a naturally occurring biodegradable polymer and readily available from agriculture. For packaging use however, Bio-VOP is not thermoplastic and its granular form is unsuitable for most uses in the plastics industry, mainly due to processing difficulties during extrusion or injection moulding. Thus, research workers have developed several methods to blend Bio-VOP appropriately for industrial uses. In particular, injections moulding processes, graft copolymerisation, and preparation of blends with thermoplastic polymers have been studied to produce solid biodegradable shaped bodies. HDPE was chosen as commercial thermoplastic materials and was added with 10% Bio-VOP for the preparation of solid biodegradable shaped bodies named as HD-VOP. The UV light exposure of HD-VOP at 12 minutes upon gives the highest strength of this material that is 17.6 MPa. The morphological structure of HD-VOP shows dwi structure surface fracture which is brittle and ductile properties.

  3. Process for crosslinking and extending conjugated diene-containing polymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (inventor); Havens, Stephen J. (inventor)

    1977-01-01

    A process using a Diels-Alder reaction which increases the molecular weight and/or crosslinks polymers by reacting the polymers with bisunsaturated dienophiles is developed. The polymer comprises at least 75% by weight based on the reaction product, has a molecular weight of at least 5000 and a plurality of conjugated 1,3-diene systems incorporated into the molecular structure. A dienophile reaction with the conjugated 1,3-diene of the polymer is at least 1% by weight based on the reaction product. Examples of the polymer include polyesters, polyamides, polyethers, polysulfones and copolymers. The bisunsaturated dienophiles may include bis-maleimides, bis maleic and bis tumaric esters and amides. This method for expanding the molecular weight chains of the polymers, preferable thermoplastics, is advantageous for processing or fabricating thermoplastics. A low molecular weight thermoplastic is converted to a high molecular weight plastic having improved strength and toughness for use in the completed end use article.

  4. 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.

  5. Metallic glass mold insert for hot embossing of polymers

    NASA Astrophysics Data System (ADS)

    Ma, J.; Zhang, X.; Wang, W. H.

    2012-07-01

    Molding of micro components from thermoplastic polymers (TPs) has become a routinely used industrial production process. To find hard, ductile and durable material for mold insert and to fabricate the mold insert are two big challenges for the thermoplastic polymers fabrication techniques. We report that a Pd-based metallic glass (MG) mold insert was readily fabricated in its supercooled liquid region, and the atomic force microscope measurement and time-temperature-transformation analysis show that the metallic glass mold insert has very fine surface quality and long service life. We show that the metallic glasses, which have remarkable mechanical properties and excellent thermoplastic forming ability, are new ideal materials for hot embossing mold insert of thermoplastic polymers.

  6. Thermoplastics Properties J. D. Muzzy

    E-print Network

    Colton, Jonathan S.

    .3.4.1.4 Acrylics 2.3.4.1.5 Fluoropolymers 2.3.4.1.6 Polyesters 2.3.4.1.7 Polyamides (Nylons) 2.3.4.1.8 Polyimides 2. From this perspective, crystalline polymers have thermally reversible crosslinks which enable them

  7. Thermoplastic pultrusion development and characterization of residual in pultruded composites with modeling and experiments

    NASA Astrophysics Data System (ADS)

    Jamiyanaa, Khongor

    Pultrusion processing is a technique to make highly aligned fiber reinforced polymer composites. Thermoset pultrusion is a mature process and well established, while thermoplastic pultrusion in still in its infancy. Thermoplastic pultrusion has not been well established because thermoplastic resins are difficult to process due to their high viscosity. However, thermoplastic resins offer distinct advantages that make thermoplastic pultrusion worth exploring. The present work centers on developing a method to design and validate a die for a thermoplastic pultrusion system. Analytical models and various software tools were used to design a pultrusion die. Experimental measurements have been made to validate the models. One-dimensional transient heat transfer analysis was used to calculate the time required for pre-impregnated E-Glass/Polypropylene tapes to melt and consolidate into profiled shapes. Creo Element/Pro 1.0 was used to design the die, while ANSYS Work Bench 14.0 was used to conduct heat transfer analysis to understand the temperature profile of the pultrusion apparatus. Additionally Star-CCM+ was used to create a three-dimensional fluid flow model to capture the molten polymer flow inside the pultrusion die. The fluid model was used to understand the temperature of the flow and the force required to pull the material at any given temperature and line speed. A complete pultrusion apparatus including the die, heating unit, cooling unit, and the frame has been designed and manufactured as guided by the models, and pultruded profiles have been successfully produced. The results show that the analytical model and the fluid model show excellent correlation. The predicted and measured pulling forces are in agreement and show that the pull force increases as the pull speed increases. Furthermore, process induced residual stress and its influence on dimensional instability, such as bending or bowing, on pultruded composites was analyzed. The study indicated that unbalanced layup can produce asymmetrical residual stress through the thickness and causes the part to bow. Furthermore, the residual stress through the thickness was mapped with excellent accuracy. A design of experiments around the processing parameters indicated that increase in pull speed or decrease in die temperature increased the residual stress within the part.

  8. Characterization of flammability properties of some thermoplastic and thermoset resins. [for aircraft interiors

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    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 included polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated included 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.

  9. Assessment of relative flammability and thermochemical properties of some thermoplastic materials

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    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) thermal mechanical properties such as glass transition and melt temperature, (2) changes in polymer enthalpy by differential scanning calorimetry, (3) thermogravimetric analysis in an anaerobic and oxidative environment, (4) oxygen index, (5) smoke evolution, (6) relative toxicity of the volatile products of pyrolysis, and (7) selected physical properties. The generic polymers which were evaluated included: acrylonitrile-butadiene-styrene, bisphenol A polycarbonate, bisphenol fluorenone carbonatedimethylsiloxane 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 rankings of some of the flammability, smoke and toxicity properties are presented.

  10. Polymer bonding process for nanolithography

    NASA Astrophysics Data System (ADS)

    Borzenko, T.; Tormen, M.; Schmidt, G.; Molenkamp, L. W.; Janssen, H.

    2001-10-01

    We have developed a lithography process which originates from imprint lithography and offers advantages over it. Unlike imprint lithography, not only the sample but also the mold is covered with a thermoplastic polymer. The mold and sample are brought into contact, pressed together and heated above the glass transition temperature of the thermoplast, causing the two polymer layers to become bonded (glued) together. A special treatment of the mold and sample surface causes the polymer film to stick only to the substrate after cooling. The bonding occurs at pressures and temperatures lower than those usually applied in imprint technology, and eliminates problems in conventional imprint technology that are related to lateral transport of the polymer.

  11. Vegetable Oil Derived Solvent, and Catalyst Free “Click Chemistry” Thermoplastic Polytriazoles

    PubMed Central

    Floros, Michael C.; Leão, Alcides Lopes; Narine, Suresh S.

    2014-01-01

    Azide-alkyne Huisgen “click” chemistry provides new synthetic routes for making thermoplastic polytriazole polymers—without solvent or catalyst. This method was used to polymerize three diester dialkyne monomers with a lipid derived 18 carbon diazide to produce a series of polymers (labelled C18C18, C18C9, and C18C4 based on monomer chain lengths) free of residual solvent and catalyst. Three diester dialkyne monomers were synthesized with ester chain lengths of 4, 9, and 18 carbons from renewable sources. Significant differences in thermal and mechanical properties were observed between C18C9 and the two other polymers. C18C9 presented a lower melting temperature, higher elongation at break, and reduced Young's modulus compared to C18C4 and C18C18. This was due to the “odd-even” effect induced by the number of carbon atoms in the monomers which resulted in orientation of the ester linkages of C18C9 in the same direction, thereby reducing hydrogen bonding. The thermoplastic polytriazoles presented are novel polymers derived from vegetable oil with favourable mechanical and thermal properties suitable for a large range of applications where no residual solvent or catalyst can be tolerated. Their added potential biocompatibility and biodegradability make them ideal for applications in the medical and pharmaceutical industries. PMID:25032224

  12. Thermoplastic/Melt-Processable Polyimides

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.; Burks, H. D.

    1984-01-01

    Several polyimides were prepared which show promise for aircraft composite applications. This was achieved through a systematic polymer synthesis program where the glass transition temperatures were greatly lowered when compared to the older polyimide systems. Several of the materials were shown to be hot-melt processable and are attractive matrix resin candidates especially in light of their high g(sub Ic) values. At least two of these polyimides are available for evaluation and others are on the research horizon.

  13. Thermoplastic shape-memory polyurethanes based on natural oils

    NASA Astrophysics Data System (ADS)

    Saralegi, Ainara; Foster, E. Johan; Weder, Christoph; Eceiza, Arantxa; Corcuera, Maria Angeles

    2014-02-01

    A new family of segmented thermoplastic polyurethanes with thermally activated shape-memory properties was synthesized and characterized. Polyols derived from castor oil with different molecular weights but similar chemical structures and a corn-sugar-based chain extender (propanediol) were used as starting materials in order to maximize the content of carbon from renewable resources in the new materials. The composition was systematically varied to establish a structure-property map and identify compositions with desirable shape-memory properties. The thermal characterization of the new polyurethanes revealed a microphase separated structure, where both the soft (by convention the high molecular weight diol) and the hard phases were highly crystalline. Cyclic thermo-mechanical tensile tests showed that these polymers are excellent candidates for use as thermally activated shape-memory polymers, in which the crystalline soft segments promote high shape fixity values (close to 100%) and the hard segment crystallites ensure high shape recovery values (80-100%, depending on the hard segment content). The high proportion of components from renewable resources used in the polyurethane formulation leads to the synthesis of bio-based polyurethanes with shape-memory properties.

  14. Thermal stresses in aluminum 6061 and nylon 66 long fiber thermoplastic (LFT) composite joint in a tailcone

    Microsoft Academic Search

    Rahul R. Kulkarni; Krishan K. Chawla; Uday K. Vaidya; James M. Sands

    2007-01-01

    The present paper involves a metal\\/polymer joint in a tailcone in a kinetic energy penetrator (KEP), one of the ammunition\\u000a types used by the military. It is currently made of aluminum 7075 alloy, which could be partly replaced by long fiber thermoplastic\\u000a (LFT) composite. Two different types of aluminum insert geometries were considered, viz., beaded and threaded. Thermal stresses\\u000a set

  15. Production of continuous fiber thermoplastic composites by in-situ pultrusion

    NASA Astrophysics Data System (ADS)

    Epple, S.; Bonten, C.

    2014-05-01

    The constructive design in the automotive industry, but also in many other industrial sectors has changed steadily over the past decades. It became much more complex due to e.g. increased use of hybrid materials. Combined with the desire to minimize the weight of vehicles and thus the CO2 emissions, the use of low density materials and especially fiber-reinforced plastics is increasing. E.g. Continuous fiber thermoplastic composites are used to reinforce injection molded parts. Low viscosity monomers like caprolactam, which is used to produce polyamide 6 by anionic polymerization are able to easily impregnate and penetrate the textile reinforcement. After wetting the fibers, the ring-opening polymerization starts and the matrix is becoming a polymer. At IKT, a method based on the RIM process (reaction injection molding) was developed to produce continuous fiber thermoplastic composites with high contents of continuous glass fibers. The anionic polymerization of polyamide 6 was now combined with the pultrusion process. Continuous glass fibers are pulled through a mold and wetted with caprolactam (including activator and catalyst). After the material polymerized in the mould, the finished continuous fiber thermoplastic composites can be pulled out and is finally sawn off.

  16. Fiber-Matrix Interfacial Adhesion Improvement in Carbon Fiber-Bisphenol-A Polycarbonate Composites by Polymer Grafting

    Microsoft Academic Search

    Venkat K. Raghavendran; Lawrence T. Drzal

    2002-01-01

    Fiber-matrix interfacial adhesion in thermoplastic composites is generally poor due to the lack of formation of strong covalent and\\/or ionic bonds between the generally inert thermoplastic resins and the surface of the reinforcing fiber. Adhesion can be improved by forming covalent linkages between the fiber and the matrix by grafting a polymer of appropriate compatibility, molecular weight, and sufficient density

  17. Challenges in Biomass–Thermoplastic Composites

    Microsoft Academic Search

    Roger M. Rowell

    2007-01-01

    Wood and other biomass resources have been blended with thermoplastic such as polyethylene, polypropylene, polylactic acid\\u000a and polyvinyl chloride to form wood plastic composites (WPC). WPCs have seen a large growth in the United States in recent\\u000a years mainly in the residential decking market with the removal of CCA treated wood decking from residential markets. While\\u000a there are many successes

  18. Rheological and Microstructural Features of Phase Transitions in Composite Polymer Materials Based on Tar and Polyethylene

    NASA Astrophysics Data System (ADS)

    Dolomatov, M. Yu.; Dezortsev, S. V.; Bakhtizin, R. Z.; Kharisov, B. R.; Nigmatullina, I. R.

    2014-03-01

    The change in the structure of tar- and polyethylene-based petroleum and polymer systems has been investigated by the methods of viscosity measurement and atomic force scanning microscopy. It has been established that the structural change of a composite petroleum and polymer thermoplastic material in the region of phase transitions of the 2nd kind results from the collapse of polymer coils and the formation of globules that subsequently aggregate. It has been shown using atomic-force-microscopy that a volume superlattice is formed from polymer globules in thermoplastic petroleum polymers in the region of phase transition of the 2nd kind.

  19. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

    McCool, Rauri; Murphy, Adrian; Wilson, Ryan; Jiang Zhenyu; Price, Mark [School of Mechanical and Aerospace Engineering, Queen's University Belfast, Northern Ireland (United Kingdom)

    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 thermoplastic based composite laminate is investigated followed by post processed part characterization. Key findings include an optimized composite processing window, and the influence of raw material blank forming temperature and mould tool temperature on part crystallinity and flexural strength. This process study forms one element of a major project structure which has been designed to address the gap between design, analysis and manufacturing, using at its core, a digital framework for the creation and management of performance parameters related to the lifecycle performance of thermoplastic composite structures.

  20. Liquid crystal polymer (LCP) for MEMS: processes and applications

    Microsoft Academic Search

    Xuefeng Wang; Jonathan Engel; Chang Liu

    2003-01-01

    In this paper we discuss newly developed microfabrication methods for liquid crystal polymer (LCP). LCP is a thermoplastic polymer made of aligned molecule chains with crystal-like spatial regularity. It exhibits unique electrical, physical and chemical properties, making it suitable for certain MEMS applications. MEMS-compatible fabrication processes such as metallization, plasma bulk etching and thermal bonding have been developed in our

  1. A modeling approach to thermoplastic pultrusion. I - Formulation of models

    NASA Astrophysics Data System (ADS)

    Astrom, B. T.; Pipes, R. B.

    1993-06-01

    Models to predict temperature and pressure distributions within a thermoplastic composed as it travels through a pultrusion line and a model to predict the pulling resistance of a die are presented and discussed. A set of mathematical models of the thermoplastic pultrusion process comprising temperature, pressure, and pulling force models are discussed and extensively verified with experimental data.

  2. 3-D Nano-Fiber Manufacturing by Controlled Pulling of Liquid Polymers using Nano-Probes

    E-print Network

    Sitti, Metin

    3-D Nano-Fiber Manufacturing by Controlled Pulling of Liquid Polymers using Nano-Probes Amrinder S nano-fibers by using precise positioning and temperature control. AFM nano-probe is used to pull or extrude thermoset or thermoplastic polymers precisely to fabricate 3-D polymer nano-fiber structures

  3. Thermoplastic encapsulation of waste surrogates by high-shear mixing

    SciTech Connect

    Lageraaen, P.R.; Kalb, P.D.; Patel, B.R.

    1995-12-01

    Brookhaven National Laboratory (BNL) has developed a robust, extrusion-based polyethylene encapsulation process applicable to a wide range of solid and aqueous low-level radioactive, hazardous and mixed wastes. However, due to the broad range of physical and chemical properties of waste materials, pretreatment of these wastes is often required to make them amenable to processing with polyethylene. As part of the scope of work identified in FY95 {open_quotes}Removal and Encapsulation of Heavy Metals from Ground Water,{close_quotes} EPA SERDP No. 387, that specifies a review of potential thermoplastic processing techniques, and in order to investigate possible pretreatment alternatives, BNL conducted a vendor test of the Draiswerke Gelimat (thermokinetic) mixer on April 25, 1995 at their test facility in Mahwah, NJ. The Gelimat is a batch operated, high-shear, high-intensity fluxing mixer that is often used for mixing various materials and specifically in the plastics industry for compounding additives such as stabilizers and/or colorants with polymers.

  4. Tough poly(arylene ether) thermoplastics as modifiers for bismaleimides

    NASA Technical Reports Server (NTRS)

    Stenzenberger, H. D.; Roemer, W.; Hergenrother, P. M.; Jensen, B. J.

    1989-01-01

    Several aspects of research on thermoplastics as toughness modifiers are discussed, including the contribution of the backbone chemistry and the concentration of the poly(arylene ether) thermoplastic to fracture toughness, influence of the molecular weight of the poly(arylene ether) thermoplastic on neat resin fracture toughness, and the morphology of the thermoplastic modified networks. The results show that fracture toughness of brittle bismaleimide resins can be improved significantly with poly(arylene ether) thermoplastic levels of 20 percent by weight, and that high molecular weight poly(arylene ether) based on bisphenol A provides the highest degree of toughening. Preliminary composite evaluation shows that improvements in neat resin toughness translate into carbon fabric composite.

  5. 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(?-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 morphology during the shape memory cycle. Then, in Chapter 5, the role of Polyhedral oligosilsesquioxane (POSS) in suppressing enzymatic degradation of PCL-PEG TPUs is investigated. In vitro enzymatic hydrolytic biodegradation revealed that POSS incorporation significantly suppressed degradation of PCL-PEG TPUs. All TPUs were surface-eroded by enzymatic attack in which the chemical composition and the bulk mechanical properties exhibited little changes. A surface passivation mechanism is proposed to explain the protection of POSS-containing TPUs from enzymatic degradation. Finally, Chapter 6 presents another POSS-based TPUs system with PLA-based polyol as the glassy soft block. Manipulation of the final thermal and mechanical properties is discussed in terms of different polyols and POSS used. The free recovery and the constrained recovery responses of the polymer films were demonstrated as a function of the prior "fixing" deformation temperature. In addition, this family of materials was capable of memorizing their T g., where optimal recovery breadth and recovery stress were achieved when pre-deformation occurred right at Tg.

  6. Thermochemical characterization of some thermoplastic materials. [flammability and toxicity properties for aircraft interiors

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    The thermochemical and flammability characteristics of some typical thermoplastic materials currently in use or being considered for use in aircraft interiors are described. The properties studied included thermomechanical properties such as glass-transition and melt temperature, changes in polymer enthalpy, thermogravimetric analysis in anerobic and oxidative environments, oxygen index, smoke evolution, relative toxicity of the volatile products of pyrolysis, and selected physical properties. The generic polymers evaluated included acrylonitrile butadiene styrene, bisphenol A polycarbonate, 9,9 bis (4-hydroxyphenyl) fluorene polycarbonate-poly (dimethylsiloxane) 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 rankings of some of the flammability, smoke, and toxicity properties are presented. Under these test conditions, some of the advanced polymers evaluated were significantly less flammable and toxic than or equivalent to polymers in current use.

  7. An afterloading brachytherapy device utilizing thermoplastic material.

    PubMed

    Kim, T H; Gerbi, B J; Deibel, F C; Priest, J R; Khan, F M

    1989-08-01

    An afterloading brachytherapy device for treatment of residual cancer in an enucleated orbit with two cesium-137 sources was designed using a thermoplastic material, Aquaplast. The device consists of a face-mask support held in place with elastic bands around the head and an acrylic afterloading applicator. The device is very easy to make, holds the sources firmly in place, allows full mobility of the patient, and gives excellent dose distribution to the target area. It was easily tolerated by a 7-year-old child during the 50 h of treatment. PMID:2798937

  8. Properties of Starch Blends with Biodegradable Polymers

    Microsoft Academic Search

    Xiu-Li Wang; Ke-Ke Yang; Yu-Zhong Wang

    2003-01-01

    Starch, one of the most inexpensive and most readily available of all natural polymers, can be processed into thermoplastic materials only in the presence of plasticizers and under the action of heat and shear. Poor water resistance and low strength are limiting factors for the use of materials manufactured only from starch, and hence the modification of starch is often

  9. Thermoplastic starch/polyester films: effects of extrusion process and poly (lactic acid) addition.

    PubMed

    Shirai, Marianne Ayumi; Olivato, Juliana Bonametti; Garcia, Patrícia Salomão; Müller, Carmen Maria Olivera; Grossmann, Maria Victória Eiras; Yamashita, Fabio

    2013-10-01

    Biodegradable films were produced using the blown extrusion method from blends that contained cassava thermoplastic starch (TPS), poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) with two different extrusion processes. The choice of extrusion process did not have a significant effect on the mechanical properties, water vapor permeability (WVP) or viscoelasticity of the films, but the addition of PLA decreased the elongation, blow-up ratio (BUR) and opacity and increased the elastic modulus, tensile strength and viscoelastic parameters of the films. The films with 20% PLA exhibited a lower WVP due to the hydrophobic nature of this polymer. Morphological analyses revealed the incompatibility between the polymers used. PMID:23910321

  10. Blends of polyamide imides and liquid crystalline polymers

    SciTech Connect

    Isayev, A.I.; Varma, T.R. [Univ. of Akron, OH (United States)

    1995-12-01

    Poly(amide imides) (PAI) are high performance polymers which are capable of replacing metals. Though they are thermoplastics, they need highly specialized machinery for processing in order to achieve maximum property development. The difficulty in processing is mainly due to its high viscosity and melt reactivity. Attempts have been made to process the PAI precursor materials using conventional thermoplastic processing methods by blending it with a liquid crystal polymer (LCP) which is in itself a high performance polymer with easy processibility and self-reinforcing capabilities. The LCP is also capable of reducing the melt viscosity when blended with other thermoplastics. The PAI precursors were melt blended with the LCP using two methods: a corotating twin screw extruder, and a single screw extruder attached to a static mixer. The blends were injection molded and characterized both before, and after, heat treatment. Studies were done to determine the thermal, flow and mechanical properties of the blends and the pure components.

  11. Positron lifetime studies in thermoplastic polyimide test specimens

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Stclair, T. L.; Holt, W. H.; Mock, W., Jr.

    1982-01-01

    Positron lifetime measurements were made in two thermoplastic polyimide materials recently developed at Langley. The long component lifetime values in polyimidesulfone samples are 847 + or - 81 Ps (dry) and 764 + or - 91 Ps (saturated). The corresponding values in LARC thermoplastic imides are 1080 + or - 139 Ps (dry) and 711 + or - 96 Ps (saturated). Clearly, the presence of moisture has greater effect on positron lifetime in LARC thermoplastic imides than in the case of polyimidesulfones. This result is consistent with the photomicrographic observations made on frozen water saturated specimens of these materials.

  12. Thermal stabilities of drops of burning thermoplastics under the UL 94 vertical test conditions.

    PubMed

    Wang, Yong; Zhang, Jun

    2013-02-15

    The properties of polymer melts will strongly affect the fire hazard of the pool induced by polymer melt flow. In this study the thermal stabilities of eight thermoplastic polymers as well as their melting drops generated under the UL 94 vertical burning test conditions were investigated by thermogravimetric experiments. It was found that the kinetic compensation effect existed for the decomposition reactions of the polymers and their drops. For polymethylmethacrylate (PMMA), high impact polystyrene (HIPS), poly(acrylonitrile-butadiene-styrene) (ABS), polyamide 6 (PA6), polypropylene (PP) and low density polyethylene (LDPE), the onset decomposition temperature and the two decomposition kinetic parameters (the pre-exponential factor and the activation energy) of the drop were less than those of the polymer. However, the onset decomposition temperature and the two kinetic parameters of PC's drop were greater than those of polycarbonate (PC). Interestingly, for polyethylenevinylacetate (EVA18) the drop hardly contained the vinyl acetate chain segments. Similarly, for the PMMA/LDPE blends and the PMMA/PP blends, when the volume fraction of PMMA was less than 50% the drop hardly contained PMMA, implying that the blend would not drip until PMMA burned away and its surface temperature approached the decomposition temperature of the continuous phase composed of LDPE or PP. PMID:23298738

  13. Structure and properties of thermotropic liquid crystal polymer and poly(ethylene 2,6-naphthalate) blend fibers

    Microsoft Academic Search

    Seong Yun Kim; Jun Young Kim; Seong Hun Kim

    2008-01-01

    BACKGROUND: The melt blending of thermotropic liquid crystal polymers (TLCPs) using conventional thermoplastics has attracted much attention due to the improved strength and tensile modulus of the resulting polymer composites. Moreover, because of their low melt viscosity, the addition of small amounts of TLCPs can reduce the melt viscosity of polymer blends, thereby enhancing the processability. RESULTS: In this study,

  14. Plate heat exchangers in liquid-crystal polymers

    Microsoft Academic Search

    J. C. Deronzier; G. Bertolini

    1997-01-01

    A new concept for a liquid-liquid plate heat exchanger has been studied using thermoplastic polymers. Considering their advantages, polymers called LCP ‘liquid crystal polymers’, have been developed in the laboratory from a base formulation of pure LCP (SPER1) to improved formulations (SPER12) using fillers as silica powder, glass and carbon fibres. A fully aromatic structure (SPER12FA) and a modified fully

  15. Coupling of waste water treatment with storage polymer production

    Microsoft Academic Search

    H. Chua; P. H. F. Yu; L. Y. Ho

    1997-01-01

    Storage polymers in bacterial cells can be extracted and used as biodegradable thermoplastics. However, widespread applications\\u000a have been limited by high production costs. In this study, activated sludge bacteria in a conventional waste water treatment\\u000a system were induced, by controlling the carbon-nitrogen (C:N) ratio in the reactor liquor, to accumulate storage polymers.\\u000a Specific polymer yield increased to a maximum of

  16. Phase transformations in tribosystems with metal-polymer components

    Microsoft Academic Search

    A. A. Ryskulov; V. A. Liopo; E. V. Ovchinnikov; E. I. Eisymont

    2011-01-01

    The paper considers the study of the mechanism of nanophase transformations in metal-polymer composite materials based on\\u000a thermoplastic matrices. It is shown that the reversible transition nanometal + polymer ? metal-containing high-molecular compound,\\u000a which results from the transformation of the adsorption bonds between the components into valent bonds, improves the performance\\u000a characteristics of articles made of metal-polymer composites, including their

  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. Heating of thermoplastic-based unidirectional composite prepregs

    SciTech Connect

    Wang, X.; Weber, M.E.; Charrier, J.M. (McGill Univ., Montreal (Canada))

    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.

  19. Hybrid yarn for thermoplastic fibre composites Publications Department

    E-print Network

    Hybrid yarn for thermoplastic fibre composites Publications Department publications Hybrid yarn Texturing of the Hybrid Yarn Materials and Mechanical Properties Press Consolidation of Hybrid Yarn Fabrics Vacuum Consolidation of Hybrid Yarn Fabrics Environmental Evaluation of Hybrid Yarn Fabrics Program

  20. Molecular weight characterization of advanced thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Young, Philip R.; Davis, Judith R.; Chang, Alice C.

    1989-01-01

    Analytical techniques including low angle laser light scattering photometry (LALLS), differential viscometry (DV), gel permeation chromatography (GPC), GPC-LALLS and GPC-DV, were used to characterize the molecular weight and molecular weight distribution of several advanced thermoplastics. A discussion is presented of various molecular-weight-related parameters obtained by these techniques on an experimental polyimide and poly(arylene ether ketone) and a commercially available polysulfone. Where possible, these parameters are correlated with processability and selected mechanical properties. The molecular weight was found to vary during the thermal conversion of poly(amic acid) to polyimide. However, no change in composition of the polysulfone was noted in response to various processing procedures.

  1. Giant magnetoimpedance effect enhanced by thermoplastic drawing

    NASA Astrophysics Data System (ADS)

    Qiang, Jian; Estevez, Diana; Dong, Yaqiang; Man, Qikui; Chang, Chuntao; Wang, Xinmin; Li, Run-Wei

    2014-09-01

    We performed thermoplastic forming (TPF) on FeCoNbB metallic glass ribbons with a supercooled liquid region exceeding 100 K, and found the sample after TPF is still completely amorphous. More importantly, the giant magnetoimpedance (GMI) effect was improved after the forming process: the maximum GMI ratio and sensitivity increased from 41% to 12.3%/Oe in the case of as-cast sample to 280% and 358.2%/Oe in the case of resulting sample after TPF, respectively. The hysteresis loops and domain patterns were subsequently studied, which revealed that the primary factor leading to the improvement of the GMI effect was the enhanced longitudinal magnetic anisotropy induced by the TPF process. We therefore assume that TPF is an effective way that improves the GMI effect, which differs from conventional annealing methods.

  2. A thermo-mechanical finite deformation theory of plasticity for amorphous polymers : application to micro-hot-embossing of poly(methyl methacrylate)

    E-print Network

    Ames, Nicoli M. (Nicoli Margret), 1978-

    2007-01-01

    Amorphous thermoplastic polymers are important engineering materials; however, their nonlinear, strongly temperature- and rate-dependent elastic-visco-plastic behavior has, until now, not been very well understood. The ...

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

    SciTech Connect

    Mosin, Yu.M.; Leonov, V.G. [D.I. Mendeleev Russian Chemical and Technological Univ., Moscow (Russian Federation)

    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.

  4. Controlling the deformation behavior of thermoplastic slips with ultrasound

    Microsoft Academic Search

    S. A. Shakhov

    2007-01-01

    The effect of ultrasound on the deformation properties of thermoplastic slips was investigated. It was shown that in treatment\\u000a with ultrasound, the change in the plastic strength of beryllium oxide — thermoplastic binder casting system in the process\\u000a temperature range (40–55°C) was due to cavitation and dissipative heat release effects and can be characterized with the equation\\u000a for a thermal

  5. Interlaminate Deformation in Thermoplastic Composite Laminates: Experimental-Numerical Correlation

    Microsoft Academic Search

    M. Shen; J. Tong; S. Wang; Y. Fang

    2010-01-01

    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

  6. Conducting polymer ultracapacitor

    DOEpatents

    Shi, Steven Z. (Latham, NY); Davey, John R. (Los Alamos, NM); Gottesfeld, Shimshon (Los Alamos, NM); Ren, Xiaoming (Los Alamos, NM)

    2002-01-01

    A sealed ultracapacitor assembly is formed with first and second electrodes of first and second conducting polymers electrodeposited on porous carbon paper substrates, where the first and second electrodes each define first and second exterior surfaces and first and second opposing surfaces. First and second current collector plates are bonded to the first and second exterior surfaces, respectively. A porous membrane separates the first and second opposing surfaces, with a liquid electrolyte impregnating the insulating membrane. A gasket formed of a thermoplastic material surrounds the first and second electrodes and seals between the first and second current collector plates for containing the liquid electrolyte.

  7. Effect of thermal history on the rheology of thermoplastic polyurethanes

    NASA Astrophysics Data System (ADS)

    Yoon, Pil Joong

    The effect of thermal history on the rheological behavior of ester- and, ether-based commercial thermoplastic polyurethanes (TPUs) was investigated. It was found from 1H and 13C nuclear magnetic resonance (NMR) spectroscopy that the ester-based TPU consisted of 4,4'-diphenylmethane diisocyanate (MDI) and butane diol (BDO) as hard segments and poly(butylene adipate) as soft segments, and the ether-based TPU consisted of MDT-BDO as hard segments and poly(oxytetramethylene) as soft segments. During isothermal annealing, the dynamic storage and loss moduli (G' and G'' ) of specimens, which had been prepared by injection molding at different temperatures, were monitored at a fixed angular frequency. It was found that thermal history of specimens had a profound influence on the variations of G' and G' ' with time observed during isothermal annealing. Isochronal dynamic temperature sweep experiments indicated that the TPUs exhibit hysteresis effect during heating and cooling, very similar to that observed in microphase-separated block polymers and thermotropic liquid-crystalline polymers reported in the literature. It was found that time-temperature superposition failed to produce reduced (or master) plots for the TPUs employed. This conclusion was reinforced by the temperature dependence of log G ' versus log G'' plots over the entire range of temperatures (110--190°C) investigated, suggesting that the morphological state of the TPU specimens varied with temperature. Little evidence was found from differential scanning calorimetry that thermal transitions took place in the TPU specimens during isothermal annealing, while values of G' and G' ' were found to vary with time. Measurements were taken of N-H stretching absorption bands in the Fourier transform infrared (FTIR) spectra during isothermal annealing at 170°C for specimens prepared by injection molding at different temperatures. The analysis of FTIR spectra indicated that variations of hydrogen bonding with time during isothermal annealing resemble very much variations of G' with time during isothermal annealing. Little evidence was found from 1H and 13C NMR spectroscopy that exchange reactions took place in the TPU specimens during isothermal annealing at elevated temperatures. It is concluded from the present study that microphase separation transition or order-disorder transition in TPU cannot be determined from oscillatory shear rheometry.

  8. Polymer alloys with balanced heat storage capacity and engineering attributes and applications thereof

    DOEpatents

    Soroushian, Parviz (Lansing, MI)

    2002-01-01

    A thermoplastic polymer of relatively low melt temperature is blended with at least one of thermosets, elastomers, and thermoplastics of relatively high melt temperature in order to produce a polymer blend which absorbs relatively high quantities of latent heat without melting or major loss of physical and mechanical characteristics as temperature is raised above the melting temperature of the low-melt-temperature thermoplastic. The polymer blend can be modified by the addition of at least one of fillers, fibers, fire retardants, compatibilisers, colorants, and processing aids. The polymer blend may be used in applications where advantage can be taken of the absorption of excess heat by a component which remains solid and retains major fractions of its physical and mechanical characteristics while absorbing relatively high quantities of latent heat.

  9. Modeling and controlling topographical nonuniformity in thermoplastic micro- and nano-embossing

    E-print Network

    Taylor, Hayden Kingsley

    2009-01-01

    The embossing of thermoplastic polymeric plates is valuable for manufacturing micro- and nanofluidic devices and diffractive optics. Meanwhile, the imprinting of sub-micrometer-thickness thermoplastic layers has emerged ...

  10. Electrical Properties of a Thermoplastic Polyurethane Filled with Titanium Dioxide Nanoparticles

    SciTech Connect

    Polyzos, Georgios [ORNL; Tuncer, Enis [ORNL; Koerner, Hilmar [Air Force Research Laboratory, Wright-Patterson AFB, OH; Kidder, Michelle [ORNL; Vaia, Richard [Air Force Research Laboratory, Wright-Patterson AFB, OH; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL

    2010-01-01

    In this study we report a nanodielectric system composed of pre-synthesized nanoparticles embedded in an elastomer. Nanoparticles of titanium dioxide were synthesized in an aqueous solution of titanium chloride and polyethylene glycol. The nanoparticles were blended in a twin screw extruder with a thermoplastic, polyurethane (Morthane PS455-203), to form nanodielectrics at three different weight fractions of titanium dioxide. Impedance spectroscopy was employed to study polymer dynamics and the influence of nanoparticles on relaxation. The segmental relaxation associated with the glass transition of the polyurethane matrix, and the local relaxations associated with short range motions of polar groups were investigated at wide ranges of frequency (20 Hz-1 MHz) and temperature (300-20 K). The dielectric breakdown strength of the nanodielectrics was also measured to characterize their insulating properties and their potential for use in high voltage applications.

  11. Highly conductive thermoplastic composites for rapid production of fuel cell bipolar plates

    DOEpatents

    Huang, Jianhua [Blacksburg, VA; Baird, Donald G [Blacksburg, VA; McGrath, James E [Blacksburg, VA

    2008-04-29

    A low cost method of fabricating bipolar plates for use in fuel cells utilizes a wet lay process for combining graphite particles, thermoplastic fibers, and reinforcing fibers to produce a plurality of formable sheets. The formable sheets are then molded into a bipolar plates with features impressed therein via the molding process. The bipolar plates formed by the process have conductivity in excess of 150 S/cm and have sufficient mechanical strength to be used in fuel cells. The bipolar plates can be formed as a skin/core laminate where a second polymer material is used on the skin surface which provides for enhanced conductivity, chemical resistance, and resistance to gas permeation.

  12. Transparent thermoplastics: Replication of diffractive optical elements using micro-injection molding

    NASA Astrophysics Data System (ADS)

    Kalima, V.; Pietarinen, J.; Siitonen, S.; Immonen, J.; Suvanto, M.; Kuittinen, M.; Mönkkönen, K.; Pakkanen, T. T.

    2007-10-01

    Small plastic components with sub-micron and micron gratings for diffractive optics were prepared by micro-injection molding. The aim of the work was to improve the filling of binary diffractive gratings with high aspect ratio by varying the molding parameters. Tests were made under conventional processing conditions with four transparent thermoplastics: polycarbonate (PC), cyclo-olefin polymer (COP), styrene-acrylonitrile copolymer (SAN), and hexafluoropropylene-tetrafluoroethylene-ethylene terpolymer (HFP-TFE-Et). Melt and mold temperatures were kept as recommended by the manufacturer. Other molding parameters (injection speed, shot size, vacuum, holding pressure, and injection plunger diameter) were varied, and their effect on the profile of the gratings was measured by atomic force microscopy. The filling of the gratings (500 nm and 1000 nm) was clearly affected by injection speed, shot size, and injection piston diameter, but the most significant factor was the type of material. Replication fidelity was highest with PC and lowest with SAN.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  14. Direct molding of thermoplastic micro-parts

    NASA Astrophysics Data System (ADS)

    Quadrini, F.; Santo, L.; Trovalusci, F.

    2008-10-01

    A new micro-molding machine is described which is used to fabricate micro-parts made of a thermoplastic material. A single pellet is directly molded into a transparent mold by means of a diode laser source. A very low holding pressure is applied and no mold heating system is required; therefore the size of the micro-machine is extremely small as well as the size of the mold. The micro-machine was used to mold three different materials: high-density polyethylene (HDPE), polystyrene (PS) and acrylonitrile-butadiene-styrene (ABS). A process map was initially defined for all the materials by changing the main process variables (i.e. laser power, molding time and focalization condition). In this phase, small disks, 3.5 mm in diameter, were molded and their diameter was measured to evaluate the dimensional accuracy of the process. Subsequently, internal micro-gears in HDPE and PS and a micro-coin in ABS were molded to show the capability of the new process in the replication of the mold cavity.

  15. 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.

  16. Wear comparison of thermoplastic materials used for orthodontic retainers.

    PubMed

    Gardner, Gary D; Dunn, William J; Taloumis, Louis

    2003-09-01

    Clear thermoplastic retainers are an alternative to fixed lingual retainers and removable Hawley appliances. However, thermoplastic retainers have demonstrated poor wear resistance and durability after only a few months of use. In this study, a simulated wear device was used to compare the wear of different thermoplastic materials used for orthodontic retainers. Three thermoplastic products were evaluated: C+ (Raintree Essix, New Orleans, La),.040-in Invisacryl C (Great Lakes Orthodontics, Towanda, NY), and.040-in TR sheet material (Bay Dental Direct, Bay City, Mich). Twenty specimens were fabricated for each group. The specimens were vacuum thermoformed according to the manufacturers' recommendations and subjected to wear for 1000 cycles in a wear apparatus with steatite ceramic abraders. Depth of wear was determined by surface profilometry. The maximum peak-to-valley measurement was recorded for each specimen. Mean wear (SD) in microns was as follows: C+, 5.9 (2.4); Invisacryl C, 6.1 (2.6); and TR, 1.6 (0.9). One-way analysis of variance detected a significant difference between groups (P <.001). TR material, a hard polyethylene terephthalate glycol copolymer (PETG), demonstrated greater resistance to wear than did the other 2 materials, which were softer, polypropylene-based thermoplastics. There was no evidence to suggest a difference in mean wear between the 2 polypropylene-based materials (P >.05). PMID:12970663

  17. Study on the Functionality of Nano-Precipitated Calcium Carbonate as Filler in Thermoplastics

    Microsoft Academic Search

    Blessie A. Basilia; Marian Elaine G. Panganiban; Archilles Allen V. C. Collado; Michael Oliver D. Pesigan; Persia Ada de Yro

    2007-01-01

    This research aims to investigate the functionality of nano-precipitated calcium carbonate (NPCC) as filler in thermoplastic resins based on property enhancement. Three types of thermoplastics were used: polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC). The resins were evaluated by determining the effect of different NPCC loading on the chemical structure, thermal and mechanical properties of thermoplastics. Results showed that

  18. Hybridization of Reinforcement to Optimize Part Performance and Molding in Reinforced Thermoplastics

    Microsoft Academic Search

    Michael J. Balow; Daniel C. Fuccella

    1983-01-01

    The mechanical properties of injection moldable thermoplastics have traditionally been measured parallel to the direction of material flow. This practice, which is readily accomplished by evaluating end gated injection molded test specimens, yields somewhat optimistic values in unreinforced thermoplastics through molecular orientation. In thermoplastics incorporating fiberous reinforcements, the orientation of those reinforcements greatly accentuates property improvement in the flow direction.

  19. An analytical approach toward monitoring degradation in engineering thermoplastic materials used for electrical applications

    Microsoft Academic Search

    Sam J. Ferrito; Thomas A. Edison

    1996-01-01

    Engineering thermoplastics are being used in a broad array of applications throughout the electrical industry. Polyester thermoplastics offer desirable electrical and mechanical properties; but when used in the wrong environments, they can be susceptible to hydrolysis. Size exclusion chromatography (SEC) can be used as an analytical tool for monitoring the degree of hydrolytic degradation occurring to engineering thermoplastic materials. By

  20. Microstructural Characterization of Polymers with Positrons

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.

    1997-01-01

    Positrons provide a versatile probe for monitoring microstructural features of molecular solids. In this paper, we report on positron lifetime measurements in two different types of polymers. The first group comprises polyacrylates processed on earth and in space. The second group includes fully-compatible and totally-incompatible Semi-Interpenetrating polymer networks of thermosetting and thermoplastic polyimides. On the basis of lifetime measurements, it is concluded that free volumes are a direct reflection of physical/electromagnetic properties of the host polymers.

  1. Interlaminar fracture in carbon fiber/thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Hinkley, J. A.; Bascom, W. D.; Allred, R. E.

    1990-01-01

    The surfaces of commercial carbon fibers are generally chemically cleaned or oxidized and then coated with an oligomeric sizing to optimize their adhesion to epoxy matrix resins. Evidence from fractography, from embedded fiber testing and from fracture energies suggests that these standard treatments are relatively ineffective for thermoplastic matrices. This evidence is reviewed and model thermoplastic composites (polyphenylene oxide/high strain carbon fibers) are used to demonstrate how differences in adhesion can lead to a twofold change in interlaminar fracture toughness. The potential for improved adhesion via plasma modification of fiber surfaces is discussed. Finally, a surprising case of fiber-catalyzed resin degradation is described.

  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. Thermoplastic veils as advanced modifiers for multifunctional fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Cicala, Gianluca; Latteri, Alberta; Mannino, Salvatore; Cozzo, Giulia; Ognibene, Giulia; Recca, Antonino

    2014-05-01

    The present paper is focused on the development of a novel technique to obtain multifunctional fiber reinforced composites. The technique is based on the use of thermoplastic veils composed of nano and micro thermoplastic fibers which preferentially dissolve upon curing in the epoxy matrix. The technique allows to control the phase morphology in the inter- and intra-laminar region of the laminates. Moreover, the selective dissolution of the fibers allow to achieve tailored dispersion of different types of nanofillers in the composites to obtain a functional graded material.

  4. Thermoplastic Explosive Compositions on the Base of Hexanitrohexaazaisowurtzitane

    NASA Astrophysics Data System (ADS)

    Ilyin, V. P.; Smirnov, S. P.; Kolganov, E. V.; Pechenev, Yu. G.

    2006-08-01

    Hexanitrohexaazaisowurtzitane is an azostructural compound known as CL-20. We performed a series of experiments with CL-20 synthesized in Russia to evaluate the possibility to use it in pressed high explosive compositions. We used it in thermoplastic compositions both with an inert binder and energetic binder. The compositions were conventionally named CL-20? and CL-20A. It was determined that the thermoplastic compositions had the most high detonation parameters and a level of sensitivity to mechanical effects acceptable to allow their processing. Their detonation characteristics were compared with that of some known foreign compositions based on CL-20.

  5. Continuation of tailored composite structures of ordered staple thermoplastic material

    NASA Technical Reports Server (NTRS)

    Santare, Michael H.; Pipes, R. Byron

    1992-01-01

    The search for the cost effective composite structure has motivated the investigation of several approaches to develop composite structure from innovative material forms. Among the promising approaches is the conversion of a planar sheet to components of complex curvature through sheet forming or stretch forming. In both cases, the potential for material stretch in the fiber direction appears to offer a clear advantage in formability over continuous fiber systems. A framework was established which allows the simulation of the anisotropic mechanisms of deformation of long discontinuous fiber laminates wherein the matrix phase is a viscous fluid. Predictions for the effective viscosities of a hyper-anisotropic medium consisting of collimated, discontinuous fibers suspended in viscous matrix were extended to capture the characteristics of typical polymers including non-Newtonian behavior and temperature dependence. In addition, the influence of fiber misorientation was also modeled by compliance averaging to determine ensemble properties for a given orientation distribution. A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams such as those used in aircraft fuselage structures. Material heterogeneity can be induced during manufacturing processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing radial and tangential gradients in material properties. Two analysis procedures are used to solve the beam problems. The first method uses separate two-dimensional elasticity solutions for the stresses in the flange and web sections of the beam. The separate solutions are coupled by requiring that forces and displacements match section boundaries. The second method uses an approximate Rayleigh-Ritz technique to find the solutions for more complex beams. Analyses are performed for curved beams of various cross-sections loaded in pure bending and with a uniform distributed load. Preliminary results show that the geometry of the beam dictates the effect of heterogeneity on performance. The role of heterogeneity is larger in beams with a small average radius-to-depth ration, R/t, where R is the average radius of the beam and t is the difference between the inside and outside radii. Results of the anlysis are in the form of stresses and displacements and are compared to both mechanics of materials and numerical solutions obtained using finite element analysis.

  6. Processing and Characterization of Polymers Containing Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Haggenmueller, Reto; Fischer, Jack; Winey, Karen

    2001-03-01

    Single-wall carbon nanotubes (SWNT) possess outstanding mechanical, electrical and thermal properties that we hope to exploit in polymer composites. The full potential of SWNT can only be obtained when the nanotubes are well separated. Thus, our current efforts are focused on dispersing various SWNT materials in thermoplastic and thermoset polymers using melt mixing methods. Melt mixing is performed in a MicroCompounderâ, which has a twin screw geometry. Materials will include SWNT prepared primarily by laser ablation, amorphous thermoplastics (PMMA, PS, etc.), semicrystalline thermoplastics (PE, nylon, etc.), and UV-curable thermosets. Dispersion of the SWNT will be characterized by optical and electron microscopy and x-ray scattering. Correlations will be made between the matrix polymer, the processing conditions (time, temperature, torque, etc.), and dispersion in order to optimize the dispersion for each matrix material.

  7. Microinjection moulding of polymer microfluidic devices

    Microsoft Academic Search

    Usama M. Attia; Silvia Marson; Jeffrey R. Alcock

    2009-01-01

    Microfluidic devices have several applications in different fields, such as chemistry, medicine and biotechnology. Many research\\u000a activities are currently investigating the manufacturing of integrated microfluidic devices on a mass-production scale with\\u000a relatively low costs. This is especially important for applications where disposable devices are used for medical analysis.\\u000a Micromoulding of thermoplastic polymers is a developing process with great potential for

  8. Self reinforcing polymer composites

    SciTech Connect

    Kenig, S. [Israel Plastics and Rubber Center, Haifa (Israel)

    1993-12-31

    In the advent of liquid crystalline polymers (LCPs), self reinforcing polymer composites comprising a polymer matrix and an LCP reinforcement, have become a reality. The so called self reinforcement is due to the LCPs orientability characteristics resulting from their rigid molecular backbone and anisotropy structure in the fluid state. Orientation development takes place during melt processing of the LCP composite blends where shear as well as elongational flows occur prior to consolidation to the solid state. By proper flow control anisotropy develops and in-situ composites are obtained. Polymer composites comprising self-reinforcement by LCPs during processing induced flow, were analyzed and studied with respect to their orientation development and resultant mechanical properties. The analysis commenced with the hydrodynamics of immiscible fluids in shear and elongational flows. Based on the analysis, orientation and morphology development in capillary extrusion was studied, using a variety of thermoplastic polymer matrices like amorphous and crystalline polyamides, polycarbonate and polyester in conjunction of a naphthalene based thermotropic LCP. Based on the flow-morphology relationship the amorphous polyamide/LCP composite was further investigated as it exhibited enhanced properties. Laminated composites based on LCP/amorphous polyamide were developed composed of unidirectional extruded and drawn sheets that were subsequently compression molded. Unidirectional, +45/{minus}45 and quasi-isotropic laminates were prepared and analyzed as to their microstructure and mechanical properties.

  9. 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.

  10. Anterior deprogramming device fabrication using a thermoplastic material.

    PubMed

    Land, Martin F; Peregrina, Alejandro

    2003-12-01

    This article presents a simple and efficient technique to fabricate an anterior deprogramming device using a thermoplastic material. The material, softened by heating, is adapted to the maxillary incisors while moldable. The operator guides the mandible into closure as the material stiffens. The device is then trimmed, and a posterior centric relation record is made using the recording material of choice. PMID:14668765

  11. Study of UV-aging of thermoplastic polyurethane material

    Microsoft Academic Search

    A. Boubakri; N. Guermazi; K. Elleuch; H. F. Ayedi

    2010-01-01

    In the present work, the characteristics of thermoplastic polyurethane (TPU) material exposed to artificial weathering environment for different durations were studied. The influence on (i) appearance and morphology, (ii) thermal properties and (iii) mechanical properties evolution of the material were investigated during aging. For this purpose, ultraviolet (UV) chamber was used as accelerated aging technique. Optical and scanning electron microscopy

  12. Qualification testing of engineering thermoplastics for electrical distribution applications

    Microsoft Academic Search

    S. J. Ferrito; Thomas A. Edison

    2002-01-01

    Engineering thermoplastic materials are continually being incorporated as a cost competitive alternative for improving the performance characteristics of electrical distribution equipment and their accessories. Proper utilization of any material requires a thorough understanding of not only the inherent properties of the material, but also how it will react under various environments over a prolonged period of time. The material selection

  13. Soft and Strong Thermoplastic Elastomers Through Molecular Design

    Microsoft Academic Search

    Folusho Oyerokun; Glenn Fredrickson; Dale Handlin

    2008-01-01

    Thermoplastic elastomers (TPE) that have a low linear modulus and yet are strong at large extension are of great importance in a variety of technological applications. Current TPE designs based on ABA triblock copolymers are limited in that the maximum volume fraction of the hard A blocks, which correlates with the material strength, is restricted by the constraint that the

  14. Thermoplastic properties of fish myofibrillar proteins: application to biopackaging fabrication

    Microsoft Academic Search

    Bernard Cuq; Nathalie Gontard; Stephane Guilbert

    1997-01-01

    Thermoplastic properties of fish myofibrillar proteins were studied by dynamic mechanical thermal analysis. Important changes in dynamic mechanical properties, observed when the temperature was increased, were associated with the glass transition of fish myofibrillar proteins. The glass—rubber transition was observed between 215 and 250°C for the dry material. Addition of water or hydrophilic plasticizers (sucrose and sorbitol) induced large decreases

  15. 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) when compared with the baseline E-Glass/Nylon-6. Uni-axial tensile tests resulted in a small increase in tensile strength (˜3.2%) with 4% nanoclay loading. Also, hygrothermal aging (50°C and 100% RH) of baseline and nanoclay modified (4%) E-Glass/Nylon-6 was studied. It was observed that the moisture diffusion process followed Fickian diffusion. E-Glass/Nylon-6 modified with 4% nanoclay loading showed improved barrier performance with a significant reduction (˜30%) in moisture uptake compared to baseline E-Glass/Nylon-6 composites. Significant improvement in mechanical properties was also observed in hygrothermally aged nanocomposite specimens when compared with the aged baseline composite.

  16. Electron Beam Crosslinked Polyurethane Shape Memory Polymers with Tunable Mechanical Properties.

    PubMed

    Hearon, Keith; Nash, Landon D; Volk, Brent L; Ware, Taylor; Lewicki, James P; Voit, Walter E; Wilson, Thomas S; Maitland, Duncan J

    2013-06-01

    Novel electron beam crosslinked polyurethane shape memory polymers with advanced processing capabilities and tunable thermomechanical properties have been synthesized and characterized. We demonstrate the ability to manipulate crosslink density in order to finely tune rubbery modulus, strain capacity, ultimate tensile strength, recovery stress, and glass transition temperature. This objective is accomplished for the first time in a low-molecular-weight polymer system through the precise engineering of thermoplastic resin precursors suitable for mass thermoplastic processing. Neurovascular stent prototypes were fabricated by dip-coating and laser machining to demonstrate processability. PMID:25411531

  17. Electron Beam Crosslinked Polyurethane Shape Memory Polymers with Tunable Mechanical Properties

    PubMed Central

    Hearon, Keith; Nash, Landon D.; Volk, Brent L.; Ware, Taylor; Lewicki, James P.; Voit, Walter E.; Wilson, Thomas S.

    2014-01-01

    Novel electron beam crosslinked polyurethane shape memory polymers with advanced processing capabilities and tunable thermomechanical properties have been synthesized and characterized. We demonstrate the ability to manipulate crosslink density in order to finely tune rubbery modulus, strain capacity, ultimate tensile strength, recovery stress, and glass transition temperature. This objective is accomplished for the first time in a low-molecular-weight polymer system through the precise engineering of thermoplastic resin precursors suitable for mass thermoplastic processing. Neurovascular stent prototypes were fabricated by dip-coating and laser machining to demonstrate processability. PMID:25411531

  18. Study on the fabricating process monitoring of thermoplastic based materials packaged OFBG and their sensing properties

    NASA Astrophysics Data System (ADS)

    Wang, Chuan; Zhou, Zhi; Zhang, Zhichun; Ou, Jinping

    2007-04-01

    As common materials or engineering materials, thermoplastic resin based materials can be used not only directly fabricating products but also FRTP(fiber reinforced thermoplastic polymer) materials for other uses. As one kind of FRTP material, GFRPP(glass fiber reinforced polypropylene) has lots of merits, such as: light weight, high strength, high tenacity, high elongation percentage, good durability, reshaping character and no environmental pollution characters. And they also can be conveniently formed hoop rebar in civil engineering. While a new kind of GFRPP-OFBG smart rod which combined GFRPP and OFBG together can be used as not only structure materials but also sensing materials. Meanwhile, PP packaged OFBG strain sensor can be expected for its low modulus, good sensitivity and good durability. Furthermore, it can be used for large strain measuring. In this paper, we have successfully fabricated a new kind of GFRPP-OFBG(Glass Fiber Reinforced Polypropylene-Optic Fiber Bragg Grating) rod by our own thermoplastic pultrusion production line and a new kind of PP packaged OFBG strain sensor by extruding techniques. And we monitored the inner strain and temperature changes with tow OFBG simultaneously of the fabricating process. The results show that: OFBG can truly reflect the strain and temperature changes in both the GFRPP rod and the PP packaged OFBG, these are very useful to modify our processing parameters. And we also find that because of the shrinkage of PP, this new kind of PP packaged OFBG have -13000?? storage, and the strain sensing performance is still very well, so which can be used for large strain measuring. Besides these, GFRPP-OFBG smart rod has good sensing performance in strain sensing just like that of FRSP-OFBG rod, the strain sensitivity coefficient is about1.19pm/??. Besides these, the surface of GFRPP-OFBG rods can be handled just as steel bars and also can be bended and reshaped. These are all very useful and very important for the use of FRP materials in civil engineering structures.

  19. Positron annihilation studies of thermoplastic LCP composites

    SciTech Connect

    Naslund, R.A.; Jones, P.L.

    1995-08-03

    The time-dependent decrease in ortho-positronium (o-Ps) intensity detected in polymers during long-term positron annihilation lifetime (PALS) experiments has been extensively studied and modeled. This decrease is temperature dependent, polymer specific, source strength dependent and is noted to saturate as a function of source exposure time. Larger decreases and smaller saturation values are exhibited at lower temperatures. Additionally, at sufficiently high temperatures, a negligible decrease is detected. The time dependent decrease is recoverable at elevated temperatures. In contrast, the o-Ps lifetime component remains constant and independent of exposure time. Increasing the exposed sample volume by continuously varying the source-sample orientation dramatically decreases the reduction of o-Ps intensity.

  20. Modification, crosslinking and reactive electrospinning of a thermoplastic medical polyurethane for vascular graft applications.

    PubMed

    Theron, J P; Knoetze, J H; Sanderson, R D; Hunter, R; Mequanint, K; Franz, T; Zilla, P; Bezuidenhout, D

    2010-07-01

    Thermoplastic polyurethanes are used in a variety of medical devices and experimental tissue engineering scaffolds. Despite advances in polymer composition to improve their stability, the correct balance between chemical and mechanical properties is not always achieved. A model compound (MC) simulating the structure of a widely used medical polyurethane (Pellethane) was synthesized and reacted with aliphatic and olefinic acyl chlorides to study the reaction site and conditions. After adopting the conditions to the olefinic modification of Pellethane, processing into flat sheets, and crosslinking by thermal initiation or ultraviolet radiation, mechanical properties were determined. The modified polyurethane was additionally electrospun under ultraviolet light to produce a crosslinked tubular vascular graft prototype. Model compound studies showed reaction at the carbamide nitrogen, and the modification of Pellethane with pentenoyl chloride could be accurately controlled to up to 20% (correlation: rho=0.99). Successful crosslinking was confirmed by insolubility of the materials. Initiator concentrations were optimized and the crosslink densities shown to increase with increasing modification. Crosslinking of Pellethane containing an increasing number of pentenoyl groups resulted in decreases (up to 42%, p<0.01) in the hysteresis and 44% in creep (p<0.05), and in a significant improvement in degradation resistance in vitro. Modified Pellethane was successfully electrospun into tubular grafts and crosslinked using UV irradiation during and after spinning to render them insoluble. Prototype grafts had sufficient burst pressure (>550 mm Hg), and compliances of 12.1+/-0.8 and 6.2+/-0.3%/100 mm Hg for uncrosslinked and crosslinked samples, respectively. It is concluded that the viscoelastic properties of a standard thermoplastic polyurethane can be improved by modification and subsequent crosslinking, and that the modified material may be electrospun and initiated to yield crosslinked scaffolds. Such materials hold promise for the production of vascular and other porous scaffolds, where decreased hysteresis and creep may be required to prevent aneurismal dilation. PMID:20080215

  1. Foam injection molding of thermoplastic elastomers: Blowing agents, foaming process and characterization of structural foams

    NASA Astrophysics Data System (ADS)

    Ries, S.; Spoerrer, A.; Altstaedt, V.

    2014-05-01

    Polymer foams play an important role caused by the steadily increasing demand to light weight design. In case of soft polymers, like thermoplastic elastomers (TPE), the haptic feeling of the surface is affected by the inner foam structure. Foam injection molding of TPEs leads to so called structural foam, consisting of two compact skin layers and a cellular core. The properties of soft structural foams like soft-touch, elastic and plastic behavior are affected by the resulting foam structure, e.g. thickness of the compact skins and the foam core or density. This inner structure can considerably be influenced by different processing parameters and the chosen blowing agent. This paper is focused on the selection and characterization of suitable blowing agents for foam injection molding of a TPE-blend. The aim was a high density reduction and a decent inner structure. Therefore DSC and TGA measurements were performed on different blowing agents to find out which one is appropriate for the used TPE. Moreover a new analyzing method for the description of processing characteristics by temperature dependent expansion measurements was developed. After choosing suitable blowing agents structural foams were molded with different types of blowing agents and combinations and with the breathing mold technology in order to get lower densities. The foam structure was analyzed to show the influence of the different blowing agents and combinations. Finally compression tests were performed to estimate the influence of the used blowing agent and the density reduction on the compression modulus.

  2. The crystallization of tough thermoplastic resins in the presence of carbon fibers

    NASA Technical Reports Server (NTRS)

    Theil, Michael H.

    1988-01-01

    The presence of carbon fibers increased the crystallization rates of both PEEK and PPS thermoplastic polymers. The effect was most pronounced at higher crystallization temperatures. Isothermal crystallization rates were analyzed by applying classical phenomenological nucleation theory. Unusually high values of the so-called Avrami exponent were found for neat PEEK. Isothermal crystallization of PEEK and PPS polymers produced crystalline samples having a wide variety of melting temperatures. The melting as observed by differential scanning calorimetry occurred as dual endotherms which were called primary (higher temperature) and secondary melting peaks. Each primary peak accounted for most of the crystallinity present. The secondary peaks represented the melting of crystallites formed later than those attributable to the primary endotherms. The presence of carbon fibers increased the thermal stability of both PEEK and PPS crystallites as manifested by higher temperatures for the primary melting peaks. This may be attributable to increased crystallite size, greater crystallite perfection, and/or favorable modification of the crystallite interface. Over the range studied, crystallization temperature strongly influenced the positions of the secondary peaks but not the primary peaks.

  3. Semi-interpenetrating polymer network for tougher and more microcracking resistant high temperature polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (inventor)

    1992-01-01

    This invention is a semi-interpenetrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. An improved high temperature matrix resin is provided which is capable of performing at 316 C in air for several hundreds of hours. This resin has significantly improved toughness and microcracking resistance, excellent processability and mechanical performance, and cost effectiveness.

  4. A Structural Approach to Establishing a Platform Chemistry for the Tunable, Bulk Electron Beam Cross-Linking of Shape Memory Polymer Systems.

    PubMed

    Hearon, Keith; Besset, Celine J; Lonnecker, Alexander T; Ware, Taylor; Voit, Walter E; Wilson, Thomas S; Wooley, Karen L; Maitland, Duncan J

    2013-11-26

    The synthetic design and thermomechanical characterization of shape memory polymers (SMPs) built from a new polyurethane chemistry that enables facile, bulk and tunable cross-linking of low-molecular weight thermoplastics by electron beam irradiation is reported in this study. SMPs exhibit stimuli-induced geometry changes and are being proposed for applications in numerous fields. We have previously reported a polyurethane SMP system that exhibits the complex processing capabilities of thermoplastic polymers and the mechanical robustness and tunability of thermomechanical properties that are often characteristic of thermoset materials. These previously reported polyurethanes suffer practically because the thermoplastic molecular weights needed to achieve target cross-link densities severely limit high-throughput thermoplastic processing and because thermally unstable radiation-sensitizing additives must be used to achieve high enough cross-link densities to enable desired tunable shape memory behavior. In this study, we demonstrate the ability to manipulate cross-link density in low-molecular weight aliphatic thermoplastic polyurethane SMPs (M w as low as ~1.5 kDa) without radiation-sensitizing additives by incorporating specific structural motifs into the thermoplastic polymer side chains that we hypothesized would significantly enhance susceptibility to e-beam cross-linking. A custom diol monomer was first synthesized and then implemented in the synthesis of neat thermoplastic polyurethane SMPs that were irradiated at doses ranging from 1 to 500 kGy. Dynamic mechanical analysis (DMA) demonstrated rubbery moduli to be tailorable between 0.1 and 55 MPa, and both DMA and sol/gel analysis results provided fundamental insight into our hypothesized mechanism of electron beam cross-linking, which enables controllable bulk cross-linking to be achieved in highly processable, low-molecular weight thermoplastic shape memory polymers without sensitizing additives. PMID:25411511

  5. A Structural Approach to Establishing a Platform Chemistry for the Tunable, Bulk Electron Beam Cross-Linking of Shape Memory Polymer Systems

    PubMed Central

    Hearon, Keith; Besset, Celine J.; Lonnecker, Alexander T.; Ware, Taylor; Voit, Walter E.; Wilson, Thomas S.; Wooley, Karen L.; Maitland, Duncan J.

    2014-01-01

    The synthetic design and thermomechanical characterization of shape memory polymers (SMPs) built from a new polyurethane chemistry that enables facile, bulk and tunable cross-linking of low-molecular weight thermoplastics by electron beam irradiation is reported in this study. SMPs exhibit stimuli-induced geometry changes and are being proposed for applications in numerous fields. We have previously reported a polyurethane SMP system that exhibits the complex processing capabilities of thermoplastic polymers and the mechanical robustness and tunability of thermomechanical properties that are often characteristic of thermoset materials. These previously reported polyurethanes suffer practically because the thermoplastic molecular weights needed to achieve target cross-link densities severely limit high-throughput thermoplastic processing and because thermally unstable radiation-sensitizing additives must be used to achieve high enough cross-link densities to enable desired tunable shape memory behavior. In this study, we demonstrate the ability to manipulate cross-link density in low-molecular weight aliphatic thermoplastic polyurethane SMPs (Mw as low as ~1.5 kDa) without radiation-sensitizing additives by incorporating specific structural motifs into the thermoplastic polymer side chains that we hypothesized would significantly enhance susceptibility to e-beam cross-linking. A custom diol monomer was first synthesized and then implemented in the synthesis of neat thermoplastic polyurethane SMPs that were irradiated at doses ranging from 1 to 500 kGy. Dynamic mechanical analysis (DMA) demonstrated rubbery moduli to be tailorable between 0.1 and 55 MPa, and both DMA and sol/gel analysis results provided fundamental insight into our hypothesized mechanism of electron beam cross-linking, which enables controllable bulk cross-linking to be achieved in highly processable, low-molecular weight thermoplastic shape memory polymers without sensitizing additives. PMID:25411511

  6. 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.

  7. Controlling the wettability of hierarchically structured thermoplastics.

    PubMed

    Cortese, Barbara; Morgan, Hywel

    2012-01-10

    Surfaces play an important role in defining the properties of materials, controlling wetting, adsorption, or desorption of biomolecules, and sealing/bonding of different materials. We have combined microscale features with plasma-etched nanoscale roughness and chemical modification to tailor the wettability of the substrates. Cyclic olefin polymers and copolymers (COPs/COCs) were processed to make a range of surfaces with controlled superhydrophobic or -hydrophilic properties. The hydrophobic properties of the polymers were increased by the introduction of microstructures of varying geometry and spacing through hot embossing. The COC/COP substrates were functionalized by plasma activation in O(2), CF(4), and a mixture of both gases. The plasma etching introduces nanoscale roughness and also chemically modifies the surface, creating either highly hydrophilic or highly hydrophobic (contact angle >150°) surfaces depending on the gas mixture. The influence of geometry and chemistries was characterized by atomic force microscopy, contact angle measurements, and X-ray photoelectron spectroscopy. Measurements of the contact angle and contact angle hysteresis demonstrated long-term stability of the superhydrophobic/superhydrophilic characteristics (>6 months). PMID:22043942

  8. 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.

  9. 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.

  10. Development and application of a process model for thermoplastic pultrusion

    NASA Astrophysics Data System (ADS)

    Astrom, B. T.

    A fundamental understanding of the effects of processing parameters and die geometry in a pultrusion process requires a mathematical model in order to minimize the number of necessary experiments. Previous investigators have suggested a variety of models for thermoset pultrusion, while comparatively little effort has been spent modelling its less well-understood thermoplastic counterpart. Herein, models to describe temperature and pressure distributions within a thermoplastic composite as it travels through the pultrusion line, as well as a model to calculate the accumulated pulling resistance from a pultrusion die, are presented. The predictions of the models are compared to experimentally obtained data in terms of composite temperature and pressure and process pulling force; the correlations between predictions and experimental data are found to be good, indicating the soundness of the models. The practical usefulness of the models in terms of die design and the effects of changes in processing parameters is demonstrated with examples.

  11. 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.

  12. Rheology of a thermoplastic paste through the mushy state transition

    Microsoft Academic Search

    D. A. Barker; D. I. Wilson

    2008-01-01

    The rheology of a highly filled thermoplastic paste employed in a novel continuous casting process was investigated across the melt-mushy zone temperature transition. The paste comprises of an ultrafine (or nano-particulate) zinc oxide powder (d1,0=85nm, 50vol%) and a continuous phase consisting of a blend of organic waxes with an onset of solidification around 54?C. Data were collected over nine decades

  13. 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.

  14. Thermoplastic starch–silica–polyvinyl alcohol composites by reactive extrusion

    Microsoft Academic Search

    Kris Frost; Julien Barthes; Daniel Kaminski; Edmond Lascaris; Julie Niere; Robert Shanks

    2011-01-01

    Thermoplastic starch–silica (SiO2) PVOH composite films were created via a reactive extrusion process using tetraethyl orthosilicate (TEOS) as a precursor. Reaction efficiency was determined by X-ray fluorescence measurement of film Si content and was observed to improve with increasing TEOS concentration. Films with high SiO2 content were noted to have varying morphology and some SiO2 clusters. Mechanical properties of the

  15. Investigation of an engineering thermoplastic polyurethane by MDSC

    Microsoft Academic Search

    B. D. Dickie

    1997-01-01

    A commercial engineering thermoplastic polyurethane (ETPU) resin was investigated by modulated-temperature DSC (MDSC). Use of this recently developed technique provided an accurate measurement of the changes in heat capacity resulting from crystallization and depolymerization processes. The former process was examined in a pseudo-isothermal experiment and the latter in a dynamic one.The ETPU resin investigated in this work is crystallizable but

  16. Evaluation of wood-thermoplastic-interphase shear strengths

    Microsoft Academic Search

    A. R. Sanadi; R. M. Rowell; R. A. Young

    1993-01-01

    A macroscopic pull-out technique has been developed to determine the interphase properties in wood\\/low-molecular-weight-thermoplastic systems. Experimental variables affecting the shear properties of these types of composites were first identified so that the test could be used to compare the effect of different surface treatments on the interfacial properties. The relationship between the debonded force,F, and embedded length,L, was not linear,

  17. 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.

  18. 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.

  19. In-Mold Coating (IMC) Process for Thermoplastic Parts

    NASA Astrophysics Data System (ADS)

    Chen, Xu; Bhagavatula, Narayan; Castro, Jose M.

    2004-06-01

    In mold coating (IMC) is an environmentally friendly alternative to painting for injection molded plastic parts. IMC is carried out by injecting a liquid low viscosity thermoset material onto the surface of the thermoplastic substrate while it is still in the mold. The coating then solidifies and adheres to the substrate. IMC process is being integrated with conventional thermoplastic injection molding to improve the part surface quality and to protect it from outdoor exposure. A power law viscosity model is employed to describe the rheological behavior of the coating material. The continuous deformation of the thermoplastic substrate caused by the coating injection is analyzed by means of the PVT relationship of the substrate. The corresponding model is solved using the Control Volume based Finite Element Method (CV/FEM) to predict the fill pattern and pressure distribution during the coating flow. The predicted results are compared to experimentally obtained fill patterns. The need to include the "edge effect" and the probable reasons for deviation of pressures from experimental observations are also discussed.

  20. 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 using the solvent extraction and gravimetry technique. Additionally, the effect of continuity on rheological behaviour of TPE nanocomposites was investigated. The ultimate goal in this field is to maximize the rubber like behaviour by controlling the blend morphology and the level of crosslinking. Therefore, this study also covers the effects of nanoclay presence and its dispersion level on the crosslinking reaction of thermoplastic vulcanizate nanocomposites prepared by reactive extrusion. Here, the rubber phase was dynamically vulcanized using dimethylol phenolic resin or octylphenol-formaldehyde resin along with stannous chloride dihydrate as the catalyst. In the present study, the dynamic vulcanization of the prepared TPVs and corresponding nanocomposites are characterized using different criteria, such as gel content, viscosity and normalized storage modulus in the time sweep tests, nuclear magnetic resonance (NMR) signal line width, bound curative content and residual diene concentration. The combination of the above parameters appears to be sufficient to provide a clear description of the systems. The last part of the present study is devoted to find how the dispersion level of nanoclay and consequently the extent of crosslinking change the rubber like behaviour and the morphology of the prepared TPVs. Therefore, recently developed method named temperature scanning stress relaxation (TSSR) was used to estimate the rubber indices of TPVs and TPV nanocomposites. The mentioned method also successfully provided information about the extent of crosslinking reaction. It is shown that the rubber like behaviour of the blends containing 50wt% and 60wt% of EPDM in which morphological studies suggest the presence of the rubber droplets in vicinity of irregular shape rubber particles with a low level of interconnectivity, correlates with the rubber droplet size. Therefore, the nanoclay presence affects the rubber index values mainly through its effect on the size of the rubber droplets that controls the number of retraction points in the proposed buckling mechanism duri

  1. Microstructural Characterization of Polymers by Positron Lifetime Spectroscopy

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.

    1996-01-01

    Positrons provide a versatile probe for monitoring microstructural features of molecular solids. In this paper, we report on positron lifetime measurements in two different types of polymers. The first group comprises polyacrylates processed on earth and in space. The second group includes fully-compatible and totally-incompatible Semi-Interpenetrating polymer networks of thermosetting and thermoplastic polyimides. On the basis of lifetime measurements, it is concluded that free volumes are a direct reflection of physical/electromagnetic properties of the host polymers.

  2. Laser-generated Macroscopic and Microscopic Surface Structures for the Joining of Aluminum and Thermoplastics using Friction Press Joining

    NASA Astrophysics Data System (ADS)

    Fuchs, Alexander N.; Wirth, Franz X.; Rinck, Philipp; Zaeh, Michael F.

    Structural lightweight construction is increasingly utilized in the aerospace and automotive industry. Hybrid structures have great potential, especially with regard to load-specific component layouts. Usually, a surface pre-treatment is applied prior to joining dissimilar materials to improve bonding mechanisms such as form closure. In previous studies pulsed wave (pw) lasers were used for structuring metals. This paper presents the results of aluminum pre-treatment via a continuous wave (cw) single-mode fiber laser: macroscopic and microscopic structures were generated on the aluminum surface; the samples were joined with glass fiber reinforced polyamide using Friction Press Joining (FPJ), a method for joining metals and thermoplastic polymers in lap joint configuration. Using these new methods for surface structuring, shear strength was increased by 40% compared to previous studies with pw lasers.

  3. Polymer Communication Cryogenic mechanical alloying as an alternative strategy for the

    E-print Network

    the tire is found to interact chemically with PMMA or PET under the milling conditions employed here. q State University, Raleigh, NC 27695, USA c Department of Chemical Engineering, North Carolina State of thermoplastic polymers and recycled tires. Mechanical milling (one material) and mechanical alloy- ing (two

  4. Tribology of polymer composites

    SciTech Connect

    Friedrich, K. [Univ. of Kaiserslautern (Germany). Institute for Composite Materials Ltd.

    1993-12-31

    Polymer composites are more and more used as structural components which are very often subjected to friction and wear loadings under use. This overview describes the following cases: (1) short fiber/thermoplastic matrix composites and their friction and wear properties as a function of both microstructural composition and external testing conditions. Special attention is focused on the effects of different polymer matrices, fiber reinforcements, and additional internal lubricants on the coefficient of friction and the specific wear rate of these materials when sliding against hard steel counterparts. Further effects on these tribological properties due to changes in testing temperature, sliding speed and contact pressure are outlined; (2) results of sliding wear experiments with continuous glass, carbon or aramid fiber/polymer matrix composites against steel counterparts. They were used to develop a hypothetical model composite with optimum wear resistance. This was achieved for hybrids with carbon fibers parallel and aramid fibers normal to the sliding direction of the counterpart; and (3) the friction and wear performance of thin layer composites strengthened with steel backeners to sustain very high pressure loadings during sliding wear.

  5. IMPROVEMENT IN THE SIMULATION OF INJECTION MOLDED SHORT GLASS FIBER THERMOPLASTIC COMPOSITES

    E-print Network

    Wapperom, Peter

    Page 1 IMPROVEMENT IN THE SIMULATION OF INJECTION MOLDED SHORT GLASS FIBER THERMOPLASTIC COMPOSITES Abstract The mechanical properties of injection molded short-fiber reinforced thermoplastic composite parts in injection molded composite parts with a circular front is presented. The mass and momentum balance equations

  6. Improvements in the Simulation of Orientation in Injection Molding of Short Fiber Thermoplastic Composites

    E-print Network

    Wapperom, Peter

    Improvements in the Simulation of Orientation in Injection Molding of Short Fiber Thermoplastic Abstract The mechanical properties of injection molded short-fiber reinforced thermoplastic composite parts for predicting the flow-induced orientation of glass fibers in injection molded composite parts is presented

  7. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  9. 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.)

  10. 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.)

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

    SciTech Connect

    NONE

    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)

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

    SciTech Connect

    NONE

    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)

  13. Electrospinning of unidirectionally and orthogonally aligned thermoplastic polyurethane nanofibers: Fiber orientation and cell migration.

    PubMed

    Mi, Hao-Yang; Salick, Max R; Jing, Xin; Crone, Wendy C; Peng, Xiang-Fang; Turng, Lih-Sheng

    2014-04-25

    Unidirectionally and orthogonally aligned thermoplastic polyurethane (TPU) nanofibers were electrospun using a custom-built electrospinning device. The unidirectionally aligned fibers were collected using two parallel copper plates, and the orthogonally aligned fibers were collected using two orthogonal sets of parallel copper plates with alternate negative connections. Carbon nanotubes (CNT) and polyacrylic acid (PAA) were added to modify the polymer solution. It was found that both CNT and PAA were capable of increasing solution conductivity. The TPU/PAA fiber showed the highest degree of fiber orientation with more than 90% of the fibers having an orientation angle between -10° and 10° for unidirectionally aligned fibers, and for orthogonally aligned fibers, the orientation angle of 50% fibers located between -10° and 10° and 48% fibers located between 80° and 100°. Viability assessment of 3T3 fibroblasts cultured on TPU/PAA fibers suggested that the material was cytocompatible. The cells' orientation and migration direction closely matched the fibers' orientation. The cell migration velocity and distance were both enhanced with the guidance of fibers compared with cells cultured on random fibers and common tissue culture plastic. Controlling cell migration velocity and directionality may provide ways to influence differentiation and gene expression and systems that would allow further exploration of wound repair and metastatic cell behavior. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2014. PMID:24771704

  14. 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 ? cm were obtained for compression ratios up to 20%. In the DC measurements, an additional decrease of resistivity was obtained by inclusion of ?-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.

  15. Sensitivity Studies for In-Situ Automated Tape Placement of Thermoplastic Composites

    NASA Technical Reports Server (NTRS)

    Costen, Robert C.; Marchello, Joseph M.

    2004-01-01

    This modeling effort seeks to improve the interlaminate bond strength of thermoplastic carbon composites produced by the in-situ automated tape placement (ATP) process. An existing high productivity model is extended to lower values of the Peclet number that correspond to the present operating conditions of the Langley ATP robot. (The Peclet number is the dimensionless ratio of inertial to diffusive heat transfer.) In sensitivity studies, all of the process and material parameters are individually varied. The model yields the corresponding variations in the effective bonding time (EBT) referred to the glass transition temperature. According to reptation theory, the interlaminate bond strength after wetting occurs is proportional to the one-fourth power of EBT. The model also computes the corresponding variations in the thermal input power (TIP) and the mass and volumetric process rates. Process studies show that a 10 percent increase in the consolidation length results in a 20 percent increase in EBT and a 5 percent increase in TIP. A surprising result is that a 10 K decrease in the tooling temperature results in a 25 percent increase in EBT and an 8 percent increase in TIP. Material studies show that a 10 K decrease in glass transition temperature results in an 8 percent increase in EBT and a 8 percent decrease in TIP. A 20 K increase in polymer degradation temperature results in a 23 percent increase in EBT with no change in TIP.

  16. Study on ternary low density polyethylene/linear low density polyethylene/thermoplastic starch blend films.

    PubMed

    Sabetzadeh, Maryam; Bagheri, Rouhollah; Masoomi, Mahmood

    2015-03-30

    In this work, low-density polyethylene/linear low-density polyethylene/thermoplastic starch (LDPE/LLDPE/TPS) films are prepared with the aim of obtaining environmentally friendly materials containing high TPS content with required packaging properties. Blending of LDPE/LLDPE (70/30 wt/wt) with 5-20 wt% of TPS and 3 wt% of PE-grafted maleic anhydride (PE-g-MA) is performed in a twin-screw extruder, followed by the blowing process. Differential scanning calorimetric results indicate starch has more pronounced effect on crystallization of LLDPE than LDPE. Scanning electron micrograph shows a fairly good dispersion of TPS in PE matrices. Fourier transfer infrared spectra confirm compatibility between polymers using PE-g-MA as the compatibilizer. Storage modulus, loss modulus and complex viscosity increase with incorporation of starch. Tensile strength and elongation-at-break decrease from 18 to 10.5 MPa and 340 to 200%, respectively when TPS increases from 5 to 20%. However, the required mechanical properties for packaging applications are attained when 15 wt% starch is added, as specified in ASTM D4635. Finally 12% increase in water uptake is achieved with inclusion of 15 wt% starch. PMID:25563952

  17. Development of LaRC (TM): IA thermoplastic polyimide coated aerospace wiring

    NASA Technical Reports Server (NTRS)

    Keating, Jack

    1995-01-01

    NASA Langley has invented LaRC(exp TM) IA and IAX which are thermoplastic polyimides with good melting, thermal and chemical resistance properties. It was the objective of this contract to prepare and extrude LaRC (exp TM) polyimide onto aircraft wire and evaluate the polymers performance in this critical application. Based on rheology and chemical resistance studies at Imitec, LaRC (exp TM) IAX melts readily in an extruder, facilitating the manufacture of thin wall coatings. The polyimide does not corode the extruder, develop gel particles nor advance in viscosity. The insulated wire was tested according to MiL-W-22759E test specifications. The resulting wire coated with LaRC (exp TM) IAX displayed exceptional properties: surface resistance, non blocking, non burning, hot fluid resistance, impulse dielectric, insulation resistance, low temperature flexibility, thermal aging, wire weight, dimensions, negligible high temperature shrinkage and stripability. The light weight and other properties merit its application in satellites, missiles and aircraft applications. The extruded IAX results in a polyimide aircraft insulation without seams, outstanding moisture resistance, continuous lengths and abrasion resistance.

  18. Electron beam surface modifications in reinforcing and recycling of polymers

    NASA Astrophysics Data System (ADS)

    Czvikovszky, T.; Hargitai, H.

    1997-08-01

    Thermoplastic polymers can be fiber-reinforced in the recycling step through a reactive modification of the interface between the polymer matrix and fiber. Recollected automobile bumpers made of polypropylene copolymers have been reinforced during the reprocessing with eight different types of high-strength fibers, with waste cord-yarns of the tire industry. A thin layer reactive interface of acrylic oligomers has been applied and activated through low energy (175 keV) electron beam (EB). The upcycling (upgrading recycling) resulted in a series of extrudable and injection-mouldable, fiber-reinforced thermoplastic of enhanced bending strength, increased modulus of elasticity and acceptable impact strength. EB treatment has been compared with conventional methods.

  19. Polylactide?Poly(6-methyl-[espilson]-caprolactone)?Polylactide Thermoplastic Elastomers

    SciTech Connect

    Martello, Mark T.; Hillmyer, Marc A. (UMM)

    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-{epsilon}-caprolactone)-polylactide aliphatic polyester ABA triblock copolymers were prepared by consecutive controlled ring-opening polymerizations. Ring-opening polymerization of neat 6-methyl-{epsilon}-caprolactone in the presence of 1,4-benzenedimethanol and tin(II) octoate afforded {alpha},{omega}-hydroxyl-terminated poly(6-methyl-{epsilon}-caprolactone). High conversions of 6-methyl-{epsilon}-caprolactone (>96%) afforded polymers with molar masses ranging from 12 to 98 kg mol{sup -1}, depending on monomer-to-initiator ratios, polymers with narrow, monomodal molecular weight distributions. An array of polylactide-poly(6-methyl-{epsilon}-caprolactone)-polylactide triblock copolymers with controlled molecular weights and narrow molecular weight distributions were synthesized using the telechelic poly(6-methyl-{epsilon}-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{sup -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.

  20. Fatigue performance characterisation of resistance-welded thermoplastic composites

    Microsoft Academic Search

    Martine Dubé; Pascal Hubert; Jan N. A. H. Gallet; Darko Stavrov; Harald E. N. Bersee; Ali Yousefpour

    2008-01-01

    This study investigates the fatigue performance of resistance-welded thermoplastic composites. Lap shear specimens consisting of unidirectional carbon fibre\\/poly-ether-imide (CF\\/PEI), unidirectional carbon fibre\\/poly-ether-ketone-ketone (CF\\/PEKK) and 8-harness satin weave fabric glass fibre\\/poly-ether-imide (GF\\/PEI) composites were resistance-welded using a metal mesh heating element. The specimens were fatigue-tested at various percentages of their static lap shear strengths at a load ratio R=0.1 and frequency

  1. Impact characterization of graphite fiber reinforced thermoplastic laminates

    NASA Astrophysics Data System (ADS)

    Chaudhuri, J.; Choe, G. H.; Vinson, J. R.

    1993-06-01

    Instrumented drop-weight impact testings were conducted in conjunction with the ultrasonic C-scan and scanning electron microscopy to characterize the impact response at low velocities. Thermoplastic composite materials in the simply supported case showed dramatic improvements in impact damage resistance compared to the thermoset composite materials as reported. Scanning electron microscopy examination of the fracture surface revealed fiber-matrix-debonding, fiber pull-out, and few delaminations. Matrix behavior can be characterized by a hackly appearance. On the other hand, the fracture mechanisms of the transverse normal compression and shear punch were matrix cracking and grouped lamina delamination as opposed to individual lamina delamination, respectively.

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

    PubMed

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

    2015-01-01

    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

  3. 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 results in potential energy savings of {approx}75% as compared to autoclave processing in aerospace, {approx}63% as compared to compression molding in automotive, and {approx}42% energy savings as compared to convectively heated tools in wind energy. The ability to make parts in a rapid and controlled manner provides significant economic advantages for each of the industrial segments. These attributes were demonstrated during the processing of the demonstration components on this project.

  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. Tunable wetting of polymer surfaces.

    PubMed

    Yilgor, Iskender; Bilgin, Sevilay; Isik, Mehmet; Yilgor, Emel

    2012-10-16

    A simple method was developed for the preparation of polymeric materials with controlled surface wettability or tunable surface wetting. The method is applicable to a large number of polymers, thermoplastic or thermoset. With this method, it is possible to prepare polymer surfaces with static water contact angles ranging from 0° (superhydrophilic) to greater than 170° (superhydrophobic). The method developed is based on spin-coating of a hydrophilic/hydrophobic silica mixture dispersed in an organic solvent or solvent mixture onto the polymer surface. Depending on the hydrophilic/hydrophobic silica ratio in the coating mixture, it is possible to obtain polymer surfaces displaying gradually changing wettability from superhydrophilic to superhydrophobic. In this article, preparation and surface characteristics of polystyrene (PS) and cross-linked epoxy resin (ER) films are provided as general examples. Polymer surfaces obtained were characterized by scanning electron microscopy, white light interferometry, atomic force microscopy, X-ray photoelectron spectroscopy, and static water contact angle measurements. Effects of the type of polymeric substrate and composition of the silica mixture on the surface behavior of the composite systems were investigated. PMID:22989033

  6. Polyphenylquinoxalines containing pendant phenylethynyl and ethynyl groups. [for thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M. (inventor)

    1983-01-01

    Poly(phenylquinoxaline) prepolymers containing pendant phenylethynyl and ethynyl groups are disclosed along with the process for forming these polymers. Monomers and the process for producing same that are employed to prepare the polymers are also disclosed.

  7. 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.

  8. Advanced Laser Transmission Welding Strategies for Fibre Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Wippo, V.; Jaeschke, P.; Brueggmann, M.; Suttmann, O.; Overmeyer, L.

    Laser transmission welding can be used to join endless fibre reinforced thermoplastics. The welding temperature is affected by the heat conduction along carbon fibresand depends on the local orientation of the fibres in the weld seam and the laser welding technique itself. In these investigations the heat development during the welding with quasi-static temperature fields, which is a combination of two laser welding techniques, is evaluated and compared to welding with a homogenized intensity distribution. In order to optimize the temperature distribution over the weld seam width for both linear and curved weld seams, different scanning structures have beenadapted. The experiments were conducted with a diode laser emitting at a wavelength of 940 nm and the process was monitored by aninfrared camera. The used thermoplastics consist of laminates based on unidirectional carbon fibre reinforced polyphenylenesulfide. With the developed scanning structures, a near-homogeneous temperature distribution was generated over the width of the weld seam for curved weld seams, which is not possible by welding with a homogenized laser radiation intensity distribution.

  9. 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.

  10. 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 ?xz 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.

  11. 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. PMID:21622068

  12. 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

  13. Stamping patterns of insulated gold nanowires with self-organized ultrathin polymer films.

    PubMed

    Helt, James M; Drain, Charles Michael; Bazzan, Giorgio

    2006-07-26

    A thermal contact transfer technique is presented for the fabrication of nanoscaled to microscaled patterns of polymer-insulated metal structures on ceramic surfaces using metal-coated, thermoplastic stamps. The thermally activated formation of polymer-metal-polymer (PMP) heterostructures occurs spontaneously when a metal-coated thermoplastic stamp is compressed against a ceramic substrate and subsequently heated. The presented technique exploits the dynamics of ultrathin polymer films localized at interfaces and interfacial forces to prompt local reorganization of polymer stamp materials during processing. Intercalation of polymer stamp materials into the metal-substrate interface yields a cohesive polymer layer that binds the metal layer to the substrate. Disproportionate adhesion between the bulk polymer and the polymer layer at the stamp-metal interface leaves a capping layer upon separation of the stamp from the substrate. Here we demonstrate this technique with single use, bilevel polymer stamps which afford transfer of two distinct general products. The transfer of insulated submicrometer wide wires from the raised stamp features affords patterns of trilayered PMP structures with uniform wire dimensions. Concomitant transfer from the recessed stamp features allows fabrication of multilayered PMP architectures with sub-100 nm spacing from microstructured polymer stamps. Thus, patterns with two different insulated nanowire widths are readily fabricated in a single stamping process. A variety of ceramic substrates, thermoplastic materials, and metals can be used; e.g., inexpensive gold-coated CD or DVD media can be used as stamps, where the combination of materials dictates the relative interfacial forces and the processing parameters. PMID:16848472

  14. Polymer blends as high explosive binders

    SciTech Connect

    Hoffman, D.M.; Caley, L.E.

    1984-10-05

    One approach to high-density, high-modulus binders for explosives is to blend low-density, high-modulus polymers with high-density, low-modulus polymers. Improved properties, which miscible pairs theoretically should have, are discussed. Two attempts to achieve miscibility between a high-density fluoropolymer (Kel-F 800) and high-modulus thermoplastics (Lucite 130 and Phenoxy PKHJ) were unsuccessful. These blends are immiscible and their physical properties are additive or not significantly enhanced. Anelastic properties of the blends indicate phase separation by the presence of two glass transitions, one associated with each phase. Unfortunately, neither of these pairs has merit as an improved plastic-bonded explosive binder. However, a compatible (miscible) pair would be an improved binder if the appropriate polymer pair could be found.

  15. 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.

  16. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  17. Polymer films

    DOEpatents

    Granick, Steve (Champaign, IL); Sukhishvili, Svetlana A. (Maplewood, NJ)

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  18. High-Temperature Shape Memory Polymers

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Weiss, Robert A.

    2012-01-01

    physical conformation changes when exposed to an external stimulus, such as a change in temperature. Such materials have a permanent shape, but can be reshaped above a critical temperature and fixed into a temporary shape when cooled under stress to below the critical temperature. When reheated above the critical temperature (Tc, also sometimes called the triggering or switching temperature), the materials revert to the permanent shape. The current innovation involves a chemically treated (sulfonated, carboxylated, phosphonated, or other polar function group), high-temperature, semicrystalline thermoplastic poly(ether ether ketone) (Tg .140 C, Tm = 340 C) mix containing organometallic complexes (Zn++, Li+, or other metal, ammonium, or phosphonium salts), or high-temperature ionic liquids (e.g. hexafluorosilicate salt with 1-propyl-3- methyl imidazolium, Tm = 210 C) to form a network where dipolar or ionic interactions between the polymer and the low-molecular-weight or inorganic compound forms a complex that provides a physical crosslink. Hereafter, these compounds will be referred to as "additives". The polymer is semicrystalline, and the high-melt-point crystals provide a temporary crosslink that acts as a permanent crosslink just so long as the melting temperature is not exceeded. In this example case, the melting point is .340 C, and the shape memory critical temperature is between 150 and 250 C. PEEK is an engineering thermoplastic with a high Young fs modulus, nominally 3.6 GPa. An important aspect of the invention is the control of the PEEK functionalization (in this example, the sulfonation degree), and the thermal properties (i.e. melting point) of the additive, which determines the switching temperature. Because the compound is thermoplastic, it can be formed into the "permanent" shape by conventional plastics processing operations. In addition, the compound may be covalently cross - linked after forming the permanent shape by S-PEEK by applying ionizing radiation ( radiation, neutrons), or by chemical crosslinking to form a covalent permanent network. With respect to other shape memory polymers, this invention is novel in that it describes the use of a thermoplastic composition that can be thermally molded or solution-cast into complex "permanent" shapes, and then reheated or redissolved and recast from solution to prepare another shape. It is also unique in that the shape memory behavior is provided by a non-polymer additive.

  19. Preparation and rheological behavior of polymer-modified asphalts

    NASA Astrophysics Data System (ADS)

    Yousefi, Ali Akbar

    1999-09-01

    Different materials and methods were used to prepare and stabilize polymer-modified asphalts. Addition of thermoplastic elastomers improved some technically important properties of asphalt. Due to inherent factors like large density difference between asphalt and polyethylene, many physical methods in which the structure of asphalt is unchanged, failed to stabilize this system. The effect of addition of copolymers and a pyrolytic oil residue derived from used tire rubber were also studied and found to be ineffective on the storage stability of the polymer-asphalt emulsions while high and moderate temperature properties of the asphalt were found to be improved. Finally, the technique of catalytic grafting of polymer on the surface of high-density particles (e.g. carbon black) was used to balance the large density difference between asphalt and polymer. The resulting polymer-asphalts were stable at high temperatures and showed enhanced properties at low and high temperatures.

  20. Shrinking Polymers

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners discover that some plastics will shrink when you get them hot. Learners bake polystyrene in a regular oven and discover what happens. Safety note: Learners need an adult's help for this activity! Use this activity to talk about different types of plastics such as thermoplastics and thermosets.

  1. LDRD final report on intelligent polymers for nanodevice performance control

    SciTech Connect

    JAMISON,GREGORY M.; LOY,DOUGLAS A.; WHEELER,DAVID R.; SAUNDERS,RANDALL S.L; SHELNUTT,JOHN A.; CARR,MARTIN J.; SHALTOUT,RAAFAT M.

    2000-01-01

    A variety of organic and hybrid organic-inorganic polymer systems were prepared and evaluated for their bulk response to optical, thermal and chemical environmental changes. These included modeling studies of polyene-bridged metal porphyrin systems, metal-mediated oligomerization of phosphaalkynes as heteroatomic analogues to polyacetylene monomers, investigations of chemically amplified degradation of acid- and base-sensitive polymers and thermally responsive thermoplastic thermosets based on Diels-Alder cycloaddition chemistry. The latter class of materials was utilized to initiate work to develop a new technique for rapidly building a library of systems with varying depolymerization temperatures.

  2. Manufacturing Aspects of Advanced Polymer Composites for Automotive Applications

    NASA Astrophysics Data System (ADS)

    Friedrich, Klaus; Almajid, Abdulhakim A.

    2013-04-01

    Composite materials, in most cases fiber reinforced polymers, are nowadays used in many applications in which light weight and high specific modulus and strength are critical issues. The constituents of these materials and their special advantages relative to traditional materials are described in this paper. Further details are outlined regarding the present markets of polymer composites in Europe, and their special application in the automotive industry. In particular, the manufacturing of parts from thermoplastic as well as thermosetting, short and continuous fiber reinforced composites is emphasized.

  3. SIMULATION OF ORIENTATION IN INJECTION MOLDING OF A HIGHLY CONCENTRATED, SHORT GLASS FIBER THERMOPLASTIC COMPOSITES

    E-print Network

    Wapperom, Peter

    SIMULATION OF ORIENTATION IN INJECTION MOLDING OF A HIGHLY CONCENTRATED, SHORT GLASS FIBER approximation for predicting the flow-induced orientation of injection molded composite parts within of the fiber orientation. Introduction Fiber reinforced thermoplastic made by injection molding

  4. THERMAL DEGRADATION EFFECTS ON CONSOLIDATION AND BONDING IN THE THERMOPLASTIC FIBER-PLACEMENT PROCESS

    EPA Science Inventory

    Effects of elevated temperature exposure during thermoplastic fiber placement on bonding and consolidation are investigated experimentally for AS 4/ polyetherketoneketone (PEKK) composite. Coupons of 24 layers are consolidated on the University of Delaware Center for Composite Ma...

  5. 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.

  6. 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.

  7. Multi-objective optimization of laser transmission joining of thermoplastics

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Zhang, Cheng; Wang, Kai; Li, Pin; Hu, Yang; Wang, Kai; Liu, Huixia

    2012-11-01

    A central composite rotatable experimental design (CCRD) was used to plan the experiment of laser transmission joining of thermoplastic. Response surface methodology (RSM) was employed to establish the mathematical relationships between the joining process parameters (laser power, joining velocity, clamp pressure, scanning number) and the three responses (the joint strength, joint width and joint cost) and then the optimization capabilities in design-expert software were used to carry out the multi-objective optimization of the joining process. In this paper, the models were tested for adequacy using analysis of variance, the predicted errors were calculated, the effects of joining process parameters were determined, and the optimal conditions were identified. It is demonstrated that the predicted results of the optimization are in good agreement with the experimental results, so this study provides an effective instruction to enhance the joint quality and minimize the joint cost.

  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. 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.

  10. Starch and cellulose nanocrystals together into thermoplastic starch bionanocomposites.

    PubMed

    González, Kizkitza; Retegi, Aloña; González, Alba; Eceiza, Arantxa; Gabilondo, Nagore

    2015-03-01

    In the present work, thermoplastic maize starch based bionanocomposites were prepared as transparent films, plasticized with 35% of glycerol and reinforced with both waxy starch (WSNC) and cellulose nanocrystals (CNC), previously extracted by acidic hydrolysis. The influence of the nanofiller content was evaluated at 1 wt.%, 2.5 wt.% and 5 wt.% of WSNC. The effect of adding the two different nanoparticles at 1 wt.% was also investigated. As determined by tensile measurements, mechanical properties were improved at any composition of WSNC. Water vapour permeance values maintained constant, whereas barrier properties to oxygen reduced in a 70%, indicating the effectiveness of hydrogen bonding at the interphase. The use of CNC or CNC and WSNC upgraded mechanical results, but no significant differences in barrier properties were obtained. A homogeneous distribution of the nanofillers was demonstrated by atomic force microscopy, and a shift of the two relaxation peaks to higher temperatures was detected by dynamic mechanical analysis. PMID:25498612

  11. FIBER LENGTH DISTRIBUTION MEASUREMENT FOR LONG GLASS AND CARBON FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil [ORNL; Frame, Barbara J [ORNL; Nguyen, Ba N. [Pacific Northwest National Laboratory (PNNL); TuckerIII, Charles L. [University of Illinois, Urbana-Champaign; Velez-Garcia, Gregorio [Virginia Polytechnic Institute and State University

    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.

  12. Thermoplastic matrix composites for aeronautical applications - The amorphous/semi-crystalline blends option

    NASA Astrophysics Data System (ADS)

    Iannone, Michele; Esposito, Floriana; Cammarano, Aniello

    2014-05-01

    Blends obtained by mixing high temperature applications thermoplastics have been investigated. Namely the blends considered in this work are made by semi-crystalline thermoplastics PEEK with amorphous PEI. The final goal is to analyse the mechanical, chemical-physical and environmental resistance characteristics of these blends to evaluate their suitability as matrices of carbon reinforced composites for aeronautical structural applications. The first collected results are very promising.

  13. Mechanical Properties of Natural-Fibre-Mat- Reinforced Thermoplastics based on Flax Fibres and Polypropylene

    Microsoft Academic Search

    S. K. Garkhail; R. W. H. Heijenrath; T. Peijs

    2000-01-01

    Thermoplastic composites based on flax fibres and a polypropylene (PP) matrix were manufactured using (i) a film-stacking method based on random fibre mats and (ii) a paper making process based on chopped fibres. The influence of fibre length and fibre content on stiffness, strength and impact strength of these so-called natural-fibre-mat-reinforced thermoplastics (NMTs) is reported and compared with data for

  14. 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.

  15. An Elastic-plastic Damage Model for Long-fiber Thermoplastics

    Microsoft Academic Search

    BA Nghiep Nguyen; Vlastimil Kunc

    2010-01-01

    This article proposes an elastic-plastic damage model that combines micromechanical modeling with continuum damage mechanics to predict the stress— strain response of injection-molded long-fiber thermoplastics. The model accounts for distributions of orientation and length of elastic fibers embedded in a thermoplastic matrix whose behavior is elastic-plastic and damageable. The elastic-plastic damage behavior of the matrix is described by the modified

  16. Processing and evaluation of long fiber thermoplastic composite plates for internal fixation

    NASA Astrophysics Data System (ADS)

    Warren, Paul B.

    The metallic plates used in internal fracture fixation may have up to ten times the elastic modulus of normal bone tissue, causing stress shielding-induced osteopenia in healed bone that can lead to re-fracture after plate removal and prolonged and painful recovery. Thermoplastic polymer matrix composites reinforced with long carbon fiber are promising alternative materials for internal fixation plates because they may be produced with relative ease and be tailored to have specific mechanical properties, alleviating the stress shielding problem. Long carbon fiber-reinforced polyetheretherketone (LCF PEEK) plates were produced using the extrusion / compression molding process. Static flexural testing determined that LCF PEEK plates with rectangular cross-section had an average flexural modulus of 12 GPa, or 23% of the flexural modulus of a stainless steel plate. The LCF PEEK plates also experienced negligible (14.7%, 14.5%, and 16.7%) reductions in modulus after fatigue testing at applied moments of 2.5, 3.0, and 3.5 N•m, respectively, over 106 load cycles. Aging the plates in 0.9% NaCl solution for four and eight weeks caused 0.34% and 0.28% increases in plate mass, respectively. No significant decrease of flexural properties due to aging was detected. Differential scanning calorimetry (DSC) revealed the PEEK matrix of the plates to be 24.5% crystalline, which is lower than typical PEEK crystallinity values of 30-35%. Scanning electron microscopy (SEM) revealed three times as many fiber pullout areas in LCF PEEK fracture surfaces as in fracture surfaces of long carbon fiber-reinforced polyphenylenesulfide (LCF PPS), another plate material tested. DSC and SEM data suggest that improvements in processing conditions and fiber/matrix bonding, along with higher carbon fiber fractions, would enhance LCF PEEK plate performance. LCF PEEK remains a promising alternative to stainless steel for internal fixation plates.

  17. Modelling of the glass fiber length and the glass fiber length distribution in the compounding of short glass fiber-reinforced thermoplastics

    NASA Astrophysics Data System (ADS)

    Kloke, P.; Herken, T.; Schöppner, V.; Rudloff, J.; Kretschmer, K.; Heidemeyer, P.; Bastian, M.; Walther, Dridger, A.

    2014-05-01

    The use of short glass fiber-reinforced thermoplastics for the production of highly stressed parts in the plastics processing industry has experienced an enormous boom in the last few years. The reasons for this are primarily the improvements to the stiffness and strength properties brought about by fiber reinforcement. These positive characteristics of glass fiber-reinforced polymers are governed predominantly by the mean glass fiber length and the glass fiber length distribution. It is not enough to describe the properties of a plastics component solely as a function of the mean glass fiber length [1]. For this reason, a mathematical-physical model has been developed for describing the glass fiber length distribution in compounding. With this model, it is possible on the one hand to optimize processes for the production of short glass fiber-reinforced thermoplastics, and, on the other, to obtain information on the final distribution, on the basis of which much more detailed statements can be made about the subsequent properties of the molded part. Based on experimental tests, it was shown that this model is able to accurately describe the change in glass fiber length distribution in compounding.

  18. Hysteresis heating based induction bonding of thermoplastic composites

    Microsoft Academic Search

    W. Suwanwatana; S. Yarlagadda; J GILLESPIEJR

    2006-01-01

    The bonding of polymer matrix composites using magnetic particulate susceptor materials for hysteresis induction heating is investigated in this study. Hysteresis heating is tailored through careful design of the microstructure of magnetic particulate polymer films. The bond strength of hysteresis-welded materials is comparable to that of autoclave-welded materials while offering an order of magnitude reduction in cycle time. The relative

  19. Modelling the Young's modulus of platelet reinforced thermoplastic sheet composites

    Microsoft Academic Search

    C. J. R Verbeek; W. W Focke

    2002-01-01

    Particulate reinforced polymers is a mature field and many models are available to predict the Young's modulus of such composites. However, most existing models have a common flaw; they all predict that the composite modulus equals that of the reinforcing agent when the polymer content approaches zero. This implies, in this limit, a monolithic reinforcement whereas, in fact, it is

  20. The influence of different screw concepts while processing fibre reinforced thermoplastics with the concept of inline-compounding on an injection moulding machine

    NASA Astrophysics Data System (ADS)

    Moritzer, E.; Müller, E.; Kleeschulte, R.

    2014-05-01

    Today, the global market poses major challenges for industrial product development. Complexity, the wide range of variants, flexibility and individuality are just some of the features that products have to fulfil. Product series additionally have shorter and shorter lifetimes. Because of their high capacity for adaptation, polymers are increasingly able to substitute traditional materials such as wood, glass and metals in various fields of application [1]. But polymers can only substitute other materials if they are optimally suited to the applications in question. Hence, product-specific material development is becoming increasingly important [2]. The problem is that the traditional development process for new polymer formulations is much too complex, too slow and therefore too expensive. Product-specific material development is thus out of the question for most processors. Integrating the compounding step in the injection moulding process would lead to a more efficient and faster development process for a new polymer formulation, providing an opportunity to create new product-specific materials. This process is called inline-compounding on an injection moulding machine. In order to develop this innovative formulation concept, with the focus on fibre reinforced thermoplastics, different screw-concepts are compared with regard to the resultant performance characteristics in the part, such as mechanical properties and fibre length distribution.

  1. Study of thermal stability and degradation of fire resistant candidate polymers for aircraft interiors

    NASA Technical Reports Server (NTRS)

    Hsu, M. T. S.

    1976-01-01

    The thermochemistry of bismaleimide resins and phenolphthalein polycarbonate was studied. Both materials are fire-resistant polymers and may be suitable for aircraft interiors. The chemical composition of the polymers has been determined by nuclear magnetic resonance and infrared spectroscopy and by elemental analysis. Thermal properties of these polymers have been characterized by thermogravimetric analyses. Qualitative evaluation of the volatile products formed in pyrolysis under oxidative and non-oxidative conditions has been made using infrared spectrometry. The residues after pyrolysis were analyzed by elemental analysis. The thermal stability of composite panel and thermoplastic materials for aircraft interiors was studied by thermogravimetric analyses.

  2. Proceedings of 7th Pacific Rim Bio-based Composite Symposium. Nanjing, China. October Mechanical Properties and Decay Resistance of Wood-Polymer

    E-print Network

    -polymer composites (WPC) have been extensively used for building products, automotive, packaging materials, and other applications. WPC is subject to fungal and termite attacks due to wood components enveloped in the thermoplastic matrix. Significant efforts have been recently made to improve decay resistance of WPC with zinc

  3. Antimicrobial Polymers with Metal Nanoparticles

    PubMed Central

    Palza, Humberto

    2015-01-01

    Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms. PMID:25607734

  4. Combustion of a Polymer (PMMA) Sphere in Microgravity

    NASA Technical Reports Server (NTRS)

    Yang, Jiann C.; Hamins, Anthony; Donnelly, Michelle K.

    1999-01-01

    A series of low gravity, aircraft-based, experiments was conducted to investigate the combustion of supported thermoplastic polymer spheres under varying ambient conditions. The three types of thermoplastic investigated were polymethylmethacrylate (PMMA), polypropylene (PP). and polystyrene (PS). Spheres with diameters ranging from 2 mm to 6.35 mm were tested. The total initial pressure varied from 0.05 MPa to 0. 15 MPa whereas the ambient oxygen concentration varied from 19 % to 30 % (by volume). The ignition system consisted of a pair of retractable energized coils. Two CCD cameras recorded the burning histories of the spheres. The video sequences revealed a number of dynamic events including bubbling and sputtering, as well as soot shell formation and break-up during combustion of the spheres at reduced gravity. The ejection of combusting material from the burning spheres represents a fire hazard that must be considered at reduced gravity. The ejection process was found to be sensitive to polymer type. All average burning rates were measured to increase with initial sphere diameter and oxygen concentration, whereas the initial pressure had little effect. The three thermoplastic types exhibited different burning characteristics. For the same initial conditions, the burning rate of PP was slower than PMMA, whereas the burning rate of PS was comparable to PMMA. The transient diameter of the burning thermoplastic exhibited two distinct periods: an initial period (enduring approximately half of the total burn duration) when the diameter remained approximately constant, and a final period when the square of the diameter linearly decreased with time. A simple homogeneous two-phase model was developed to understand the changing diameter of the burning sphere. Its value is based on a competition between diameter reduction due to mass loss from burning and sputtering, and diameter expansion due to the processes of swelling (density decrease with heating) and bubble growth. The model relies on empirical parameters for input, such as the burning rate and the duration of the initial and final burning periods.

  5. Comparison of piezoresistive monofilament polymer sensors.

    PubMed

    Melnykowycz, Mark; Koll, Birgit; Scharf, Dagobert; Clemens, Frank

    2014-01-01

    The development of flexible polymer monofilament fiber strain sensors have many applications in both wearable computing (clothing, gloves, etc.) and robotics design (large deformation control). For example, a high-stretch monofilament sensor could be integrated into robotic arm design, easily stretching over joints or along curved surfaces. As a monofilament, the sensor can be woven into or integrated with textiles for position or physiological monitoring, computer interface control, etc. Commercially available conductive polymer monofilament sensors were tested alongside monofilaments produced from carbon black (CB) mixed with a thermo-plastic elastomer (TPE) and extruded in different diameters. It was found that signal strength, drift, and precision characteristics were better with a 0.3 mm diameter CB/TPE monofilament than thick (~2 mm diameter) based on the same material or commercial monofilaments based on natural rubber or silicone elastomer (SE) matrices. PMID:24419161

  6. Large-Strain Transparent Magnetoactive Polymer Nanocomposites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    2012-01-01

    A document discusses polymer nano - composite superparamagnetic actuators that were prepared by the addition of organically modified superparamagnetic nanoparticles to the polymer matrix. The nanocomposite films exhibited large deformations under a magnetostatic field with a low loading level of 0.1 wt% in a thermoplastic polyurethane elastomer (TPU) matrix. The maximum actuation deformation of the nanocomposite films increased exponentially with increasing nanoparticle concentration. The cyclic deformation actuation of a high-loading magnetic nanocomposite film was examined in a low magnetic field, and it exhibited excellent reproducibility and controllability. Low-loading TPU nanocomposite films (0.1-2 wt%) were transparent to semitransparent in the visible wavelength range, owing to good dispersion of the magnetic nanoparticles. Magnetoactuation phenomena were also demonstrated in a high-modulus, high-temperature polyimide resin with less mechanical deformation.

  7. SUPER HARD SURFACED POLYMERS

    SciTech Connect

    Mansur, Louis K [ORNL] [ORNL; Bhattacharya, R [UES, Incorporated, Dayton, OH] [UES, Incorporated, Dayton, OH; Blau, Peter Julian [ORNL] [ORNL; Clemons, Art [ORNL] [ORNL; Eberle, Cliff [ORNL] [ORNL; Evans, H B [UES, Incorporated, Dayton, OH] [UES, Incorporated, Dayton, OH; Janke, Christopher James [ORNL] [ORNL; Jolly, Brian C [ORNL] [ORNL; Lee, E H [Consultant, Milpitas, CA] [Consultant, Milpitas, CA; Leonard, Keith J [ORNL] [ORNL; Trejo, Rosa M [ORNL] [ORNL; Rivard, John D [ORNL] [ORNL

    2010-01-01

    High energy ion beam surface treatments were applied to a selected group of polymers. Of the six materials in the present study, four were thermoplastics (polycarbonate, polyethylene, polyethylene terephthalate, and polystyrene) and two were thermosets (epoxy and polyimide). The particular epoxy evaluated in this work is one of the resins used in formulating fiber reinforced composites for military helicopter blades. Measures of mechanical properties of the near surface regions were obtained by nanoindentation hardness and pin on disk wear. Attempts were also made to measure erosion resistance by particle impact. All materials were hardness tested. Pristine materials were very soft, having values in the range of approximately 0.1 to 0.5 GPa. Ion beam treatment increased hardness by up to 50 times compared to untreated materials. For reference, all materials were hardened to values higher than those typical of stainless steels. Wear tests were carried out on three of the materials, PET, PI and epoxy. On the ion beam treated epoxy no wear could be detected, whereas the untreated material showed significant wear.

  8. Thermoplastic Starch Films with Vegetable Oils of Brazilian Cerrado

    NASA Astrophysics Data System (ADS)

    Schlemmer, D.; Sales, M. J. A.

    2008-08-01

    Biodegradable polymers are one of the most promising ways to replace non-degradable polymers. TPS films were prepared by casting from cassava starch and three different vegetable oils of Brazilian Cerrado as plasticizer: buriti, macaúba and pequi. In this preliminary work it was investigated materials thermal characteristics by TG and TMA. Thermal properties of oils depends on their chemical structures. Starch and vegetable oils are natural resources that can be used how alternative to producing materials that cause minor environmental impact.

  9. Development of thermoplastic starch blown film by incorporating plasticized chitosan.

    PubMed

    Dang, Khanh Minh; Yoksan, Rangrong

    2015-01-22

    The objective of the present work was to improve blown film extrusion processability and properties of thermoplastic starch (TPS) film by incorporating plasticized chitosan, with a content of 0.37-1.45%. The effects of chitosan on extrusion processability and melt flow ability of TPS, as well as that on appearance, optical properties, thermal properties, viscoelastic properties and tensile properties of the films were investigated. The possible interactions between chitosan and starch molecules were evaluated by FTIR and XRD techniques. Chitosan and starch molecules could interact via hydrogen bonds, as confirmed from the blue shift of OH bands and the reduction of V-type crystal formation. Although the incorporation of chitosan caused decreased extensibility and melt flow ability, as well as increased yellowness and opacity, the films possessed better extrusion processability, increased tensile strength, rigidity, thermal stability and UV absorption, as well as reduced water absorption and surface stickiness. The obtained TPS/chitosan-based films offer real potential application in the food industry, e.g. as edible films. PMID:25439934

  10. The development of an alternative thermoplastic powder prepregging technique

    NASA Technical Reports Server (NTRS)

    Ogden, A. L.; Hyer, M. W.; Wilkes, G. L.; Loos, A. C.

    1992-01-01

    An alternative powder prepregging technique is discussed that is based on the deposition of powder onto carbon fibers that have been moistened using an ultrasonic humidifier. The dry fiber tow is initially spread to allow a greater amount of the fiber surface to be exposed to the powder, thus ensuring a significant amount of intimate contact between the fiber and the matrix. Moisture in the form of ultrafine water droplets is then deposited onto the spread fiber tow. The moisture promotes adhesion to the fiber until the powder can be tacked to the fibers by melting. Powdered resin is then sieved onto the fibers and then tacked onto the fibers by quick heating in a convective oven. This study focuses on the production of prepregs and laminates made with LaRC-TPI (thermoplastic polyimide) using this process. Although the process appears to be successful, early evaluation was hampered by poor interfacial adhesion. The adhesion problem, however, seems to be the result of a material system incompatibility, rather than being influenced by the process.

  11. Consolidation of graphite thermoplastic textile preforms for primary aircraft structure

    NASA Technical Reports Server (NTRS)

    Suarez, J.; Mahon, J.

    1991-01-01

    The use of innovative cost effective material forms and processes is being considered for fabrication of future primary aircraft structures. Processes that have been identified as meeting these goals are textile preforms that use resin transfer molding (RTM) and consolidation forming. The Novel Composites for Wing and Fuselage Applications (NCWFA) program has as its objective the integration of innovative design concepts with cost effective fabrication processes to develop damage-tolerant structures that can perform at a design ultimate strain level of 6000 micro-inch/inch. In this on-going effort, design trade studies were conducted to arrive at advanced wing designs that integrate new material forms with innovative structural concepts and cost effective fabrication methods. The focus has been on minimizing part count (mechanical fasteners, clips, number of stiffeners, etc.), by using cost effective textile reinforcement concepts that provide improved damage tolerance and out-of-plane load capability, low-cost resin transfer molding processing, and thermoplastic forming concepts. The fabrication of representative Y spars by consolidation methods will be described. The Y spars were fabricated using AS4 (6K)/PEEK 150g commingled angle interlock 0/90-degree woven preforms with +45-degree commingled plies stitched using high strength Toray carbon thread and processed by autoclave consolidation.

  12. 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.

  13. Chemical imaging of thermoplastic olefin (TPO) surface architecture

    SciTech Connect

    Morris, H.R. [Duquesne Univ., Pittsburgh, PA (United States). School of Pharmacy] [Duquesne Univ., Pittsburgh, PA (United States). School of Pharmacy; Turner, J.F. II [Carnegie Mellon Univ., Pittsburgh, PA (United States). Center for Light Microscope Imaging and Biotechnology] [Carnegie Mellon Univ., Pittsburgh, PA (United States). Center for Light Microscope Imaging and Biotechnology; Munro, B.; Ryntz, R.A. [Visteon Automotive Systems, Dearborn, MI (United States)] [Visteon Automotive Systems, Dearborn, MI (United States); Treado, P.J. [ChemIcon Inc., Pittsburgh, PA (United States)] [ChemIcon Inc., Pittsburgh, PA (United States)

    1999-04-13

    In the automotive industry, ethylene-propylene rubber (EPR) is mixed with polypropylene (PP) to form a thermoplastic olefin (TPO) for use as car bumpers and fascia. An adhesion promoting primer, chlorinated polyolefin (CPO), is spray coated onto the TPO surface to increase adhesion of the base and clear coat paints to the low surface free energy TPO substrate. The surface morphology of rubber domains within the CPO-coated TPO substrate contributes strongly to the material characteristics, including impact resistance and adhesion properties. However, elastomer-phase analysis is challenging using traditional microanalysis imaging techniques. The authors employ fluorescence and Raman chemical imaging to characterize the TPO architecture in order to better understand the surface properties of coated TPO. Fluorescence imaging makes use of Nile red (NR), a fluorescent solvatochromic dye, solvated in the primer, which is effective in differentiating rubber from polypropylene on the basis of large variations in the fluorescence quantum efficiency. Confocal fluorescence chemical imaging performed on T PO coated with NR-doped CPO shows a thin (2--3 {micro}m) layer of elastomer that has migrated to the TPO surface. Raman chemical imaging is in direct agreement with the fluorescence experiments by measuring the intrinsic vibrational signatures of CPO, EPR, and PP without the need for dyes or stains. Raman contrast is enhanced using cosine correlation analysis, a novel multivariate processing technique that provides chemical contrast on the basis of differences in spectral shape.

  14. Thermal imaging technique to characterize laser light reflection from thermoplastics

    NASA Astrophysics Data System (ADS)

    Azhikannickal, Elizabeth; Bates, Philip J.; Zak, Gene

    2012-07-01

    Characterization of laser light reflection during the laser transmission welding (LTW) of thermoplastics is especially important for applications in which non-zero laser incidence angles are used. At higher laser incidence angles, reflection increases and has the potential to burn surrounding features of the part to be welded. This study presents and validates a technique for laser reflection measurement. Reflected energy is absorbed by a black plastic plate (containing carbon black, which is the absorber of the reflected energy). The surface temperature of the plate is measured by an infrared (IR) camera. The distribution of reflected power required to generate this temperature profile is estimated using a simple heat transfer model. The technique was validated by irradiating the black plate by the laser directly, while observing the time-varying temperature distribution of the plate by the IR camera. In this case, good agreement was observed between the estimated total power and the actual laser input power. Good agreement also existed between the estimated power distribution and that determined experimentally via a knife edge based beam profiling technique. The thermal imaging technique was subsequently used to measure the magnitude and distribution of laser light reflection from unreinforced nylon 6. Abbreviations: LTW—laser transmission welding, CB—carbon black, IR—infrared, NPFD—normalized power flux distribution

  15. 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.

  16. Design and testing of novel piezoceramic modules for adaptive thermoplastic composite structures

    NASA Astrophysics Data System (ADS)

    Hufenbach, W.; Gude, M.; Heber, T.

    2009-04-01

    For the series production of adaptive fibre-reinforced thermoplastic structures, the development of process-adapted piezoceramic modules is gaining central importance. Therefore, thermoplastic-compatible piezoceramic modules (TPMs) are being developed which are suitable for a matrix-homogeneous adhesive-free integration of the modules in fibre-reinforced thermoplastic structures during a sequential hot-pressing process. Extensive numerical and experimental studies are available on the systematic development of the TPMs, whose thermoplastic carrier film, made, respectively, of polyetheretherketone (PEEK) or polyamide (PA), is already adapted to the matrix material of a thermoplastic composite structure and thus can be joined in a welding process without additional adhesives. The studies carried out indicate the influence of geometrical and technological parameters on the efficiency of consolidated and polarized TPMs and can thus be used to adapt the design specifications and process parameters of the TPMs. Besides these studies, a numerically based residual stress analysis shows the potential for a defined inducing of residual stresses in the TPM components.

  17. Dispersion and Characterization of Nickel Nanostrands in Thermoset and Thermoplastic Polymers

    E-print Network

    Whalen, Casey Allen

    2012-02-14

    2.3.1 CP2 composite processing with DMAc solvent ..... 18 2.3.2 Epoxy composite processing with DMAc solvent .. 18 2.3.3 Epoxy composite processing with PG solvent ..... 22 x 2.3.4 Epoxy composite processing... Optical Images of 1 wt% NiNS - CP2 ............................................ 37 18 Digital images of polished NiNS - Epoxy nano-composites ........... 42 19 OMs of 1 wt% NiNS - Epoxy with 24 hours of mixing .................... 44 xii 20 OMs...

  18. Compatibilization of thermoplastic composites based on blends of polypropylene with two liquid crystalline polymers

    Microsoft Academic Search

    Arindam Datta; Donald G. Baird

    1995-01-01

    In an earlier paper we considered the effect of polypropylene modified with maleic anhydride (MAGPP) on the properties of in situ composites based on polypropylene (PP) and a thermotropic copolyesteramide (Vectra B). In this paper we consider the effect of MAGPP on the properties of in situ composites based on PP and two different thermotropic copolyesters. It was observed that

  19. Variation of mechanical and thermal properties of the thermoplastics reinforced with natural fibers by electron beam processing

    Microsoft Academic Search

    Sok Won Kim; Seungmin Oh; Kyuse Lee

    2007-01-01

    With restrictions for environmental protection being strengthened, the thermoplastics reinforced with natural fibers (NFs) such as jute, kenaf, flax, etc., appeared as an automobile interior material instead of the chemical plastics. Regardless of many advantages, one shortcoming is the deformation after being formed in high temperature of about 200°C, caused by the poor adhesion between the natural fibers and thermoplastics.

  20. The effect of glycerol\\/sugar\\/water and sugar\\/water mixtures on the plasticization of thermoplastic cassava starch

    Microsoft Academic Search

    E. M. Teixeira; A. L. Da Róz; A. J. F. Carvalho; A. A. S. Curvelo

    2007-01-01

    The use of 2wt% sugars as co-plasticizer in combination with glycerol was investigated for thermoplastic starch (TPS) from cassava. The results were compared to those for whole cassava root TPS, which naturally contains sugars in the same proportion. The main objective was to investigate the influence of natural sugars present in the cassava root on the properties of thermoplastic starch

  1. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding.

    PubMed

    Mi, Hao-Yang; Salick, Max R; Jing, Xin; Jacques, Brianna R; Crone, Wendy C; Peng, Xiang-Fang; Turng, Lih-Sheng

    2013-12-01

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold's microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. PMID:24094186

  2. Preparation of cotton linter nanowhiskers by high-pressure homogenization process and its application in thermoplastic starch

    NASA Astrophysics Data System (ADS)

    Savadekar, N. R.; Karande, V. S.; Vigneshwaran, N.; Kadam, P. G.; Mhaske, S. T.

    2015-03-01

    The present work deals with the preparation of cotton linter nanowhiskers (CLNW) by acid hydrolysis and subsequent processing in a high-pressure homogenizer. Prepared CLNW were then used as a reinforcing material in thermoplastic starch (TPS), with an aim to improve its performance properties. Concentration of CLNW was varied as 0, 1, 2, 3, 4 and 5 wt% in TPS. TPS/CLNW nanocomposite films were prepared by solution-casting process. The nanocomposite films were characterized by tensile, differential scanning calorimetry, scanning electron microscopy (SEM), water vapor permeability (WVP), oxygen permeability (OP), X-ray diffraction and light transmittance properties. 3 wt% CLNW-loaded TPS nanocomposite films demonstrated 88 % improvement in the tensile strength as compared to the pristine TPS polymer film; whereas, WVP and OP decreased by 90 and 92 %, respectively, which is highly appreciable compared to the quantity of CLNW added. DSC thermograms of nanocomposite films did not show any significant effect on melting temperature as compared to the pristine TPS. Light transmittance ( T r) value of TPS decreased with increased content of CLNW. Better interaction between CLNW and TPS, caused due to the hydrophilic nature of both the materials, and uniform distribution of CLNW in TPS were the prime reason for the improvement in properties observed at 3 wt% loading of CLNW in TPS. However, CLNW was seen to have formed agglomerates at higher concentration as determined from SEM analysis. These nanocomposite films can have potential use in food and pharmaceutical packaging applications.

  3. Microgravity Polymers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    A one-day, interactive workshop considering the effects of gravity on polymer materials science was held in Cleveland, Ohio, on May 9, 1985. Selected programmatic and technical issues were reviewed to introduce the field to workshop participants. Parallel discussions were conducted in three disciplinary working groups: polymer chemistry, polymer physics, and polymer engineering. This proceedings presents summaries of the workshop discussions and conclusions.

  4. [Application of thermoplastic elastomer in hot-melt pressure sensitive adhesives for transtermal drug delivery].

    PubMed

    Yan, Xiaoping; Zheng, Rui; Guan, Shijie; Yi, Bowen

    2009-06-01

    Development of drug dosage forms to a great extent depends on the development of drug auxiliary materials. The development of a new type of polymeric drug auxiliary materials will bring on the developing of a novel dosage forms technology and a flood of new drug dosage forms. Thermoplastic elastomer is a new type of drug polymeric auxiliary materials, at present, which has a broad application in the field of hot-melt pressure sensitive adhesives. This review mainly discussed a new transtermal Chinese drug delivery system, including matrix composition of the formula, modified thermoplastic elastomer for hot-melt pressure sensitive adhesives and their development prospects in the traditional Chinese drug delivery system. It suggested that thermoplastic elastomer of hot-melt pressure sensitive adhesives has broad development prospects in the field of the transtermal drug delivery system for traditional Chinese medicine. PMID:19777854

  5. Isothermal elongational behavior of liquid-crystalline polymers and LCPs based blends

    Microsoft Academic Search

    Franco P. Mantia; Massimo Paci; Pierluigi L. Magagnini

    1997-01-01

    The rheological behavior of two flexible thermoplastics, Nylon-6 (Ny) and bisphenol-A polysulfone (PSu), and two wholly aromatic liquid crystalline polymers, Vectra-A900 (VA) and Vectra-B950 (VB), as well as that of Ny\\/VB and PSu\\/VA blends with 10% LCP, has been investigated by the use of capillary viscometers equipped with cylindrical dies having different length-to-diameter ratios. The elongational viscosity of all materials

  6. Novel routes to liquid-based self-healing polymer systems

    Microsoft Academic Search

    S. D. Mookhoek

    2010-01-01

    Inspired by the current state-of-the-art and the progressing advancements in the field of self-healing materials, this thesis addresses several novel routes to advance the concept of liquid-based self-healing polymer systems.\\u000aThis thesis presents the concept and characterisation of a one-component solvent-based healing mechanism for thermoplastic materials and in addition to the healing strategy, a new capsular architecture is proposed for

  7. Self-Healing Polymers and Composites

    NASA Astrophysics Data System (ADS)

    Blaiszik, B. J.; Kramer, S. L. B.; Olugebefola, S. C.; Moore, J. S.; Sottos, N. R.; White, S. R.

    2010-08-01

    Self-healing polymers and fiber-reinforced polymer composites possess the ability to heal in response to damage wherever and whenever it occurs in the material. This phenomenal material behavior is inspired by biological systems in which self-healing is commonplace. To date, self-healing has been demonstrated by three conceptual approaches: capsule-based healing systems, vascular healing systems, and intrinsic healing polymers. Self-healing can be autonomic—automatic without human intervention—or may require some external energy or pressure. All classes of polymers, from thermosets to thermoplastics to elastomers, have potential for self-healing. The majority of research to date has focused on the recovery of mechanical integrity following quasi-static fracture. This article also reviews self-healing during fatigue and in response to impact damage, puncture, and corrosion. The concepts embodied by current self-healing polymers offer a new route toward safer, longer-lasting, fault-tolerant products and components across a broad cross section of industries including coatings, electronics, transportation, and energy.

  8. Polymers Presentation

    NSDL National Science Digital Library

    This 15 page PowerPoint contains the presentation for the polymers module from Nano-Link. This lesson requires a background in eight grade science. Various details of polymers are discussed including molecular structures, cross-linked polymers, and ringed polymers. Lastly, an activity to explore cross-linked polymers is included. Visitors must complete a quick and free registration to access the materials.

  9. 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 of EAPs. The unique copolymer investigated here (i) retains its mechanical integrity when highly solvated by polar solvents, (ii) demonstrates a high degree of actuation when tested in a cantilever configuration, and (iii) avoids the shortcomings of back-relaxation/overshoot within the testing conditions when used in combination with an appropriate solvent. In the second part of this work, two chemical strategies to design midblock sulfonated block ionomers are explored. In one case, selective sulfonation of the midblocks in triblock copolymers is achieved via a dioxane:sulfur trioxide chemistry, while in the other acetyl sulfate is used for the same purpose. Excellent control on the degree of sulfonation (DOS) is achieved. The block ionomers swell in different solvents while retaining their mechanical integrity. They show disorder-order, order-order, and order-reduced order morphological transitions as DOS varies. These transitions in morphologies are reflected in their thermal behavior as well. The microstructures show periodicity, which is, again, a function of DOS. The transitions are explained in terms of the molar volume expansion and volume densification of the blocks on sulfonation. The ionic levels, morphology and periodicity in microstructure are important for applications such as actuators, sensors and fuel cell membranes. The ability to tune these aspects in the ionomers designed in this work make them potential candidates for these applications.

  10. Thermoplastic nanoclay-modified vulcanizates based on polypropylene and nitrile-butadiene rubber

    NASA Astrophysics Data System (ADS)

    Volfson, Svetoslav I.; Okhotina, Natalya A.; Nigmatullina, Alina I.; Panfilova, Olga A.

    2014-05-01

    Thermoplastic vulcanizates based on polypropylene and nitrile-butadiene rubber, containing modified organoclay were developed. It was shown that composites containing 1 to 5 pbw of Cloisite 15A montmorillonite added to rubber show improved physical-mechanical characteristics. Their swelling degree in AI-92 and motor oil was determined. The swelling degree of composites in petrol and motor oil decreases substantially, by 20-63%, due to the introduction of Cloisite 15A montmorillonite. Modification of thermoplastic vulcanizates using layered silicates raised the degradation onset temperature and decreases weight loss upon high temperature heating.

  11. Laser-bonding of long fiber thermoplastic composites for structural assemblies

    NASA Astrophysics Data System (ADS)

    Knapp, Wolfgang; Clement, S.; Franz, C.; Oumarou, M.; Renard, J.

    The use of laser light for bonding of long fiber reinforced thermoplastic composites (LFTPC) offers new possibilities to overcome the constraints of conventional joining technologies. Laser specific transmission welding procedures are known in manufacturing of short fiber thermoplastic composites. The technical basics of the joining process and an outline of some material inherent characteristics using long glass fiber reinforced composites with PA resin are discussed. The technical feasibility and the mechanical characterization of laser bonded LFTPC are demonstrated. The results show that the laser provides an alternative joining technique and offers new perspectives to assemble structural components emerging in industrial manufacturing.

  12. Sensitivity analysis for the process integrated online polarization of piezoceramic modules in thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Hufenbach, W.; Gude, M.; Modler, N.; Heber, T.; Tyczynski, T.

    2010-10-01

    The use of active composite structures in high-volume applications requires novel robust manufacturing processes as well as specially adapted functional modules. The paper presents actual research results with regard to the process-immanent polarization of novel thermoplastic-compatible piezoceramic modules (TPM) during the consolidation process of active fibre-reinforced thermoplastic composite structures. In particular the influence of varying manufacture process parameters of a hot-press process on the polarization behaviour is investigated. The main principal objective is the purposeful utilization of process parameters for polarization support.

  13. Dynamic viscoelasticities for short fiber-thermoplastic elastomer composites

    SciTech Connect

    Guo, Wuyun; Ashida, Michio (Kobe Univ., (Japan). 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.

  14. Interfacial studies in fiber-reinforced thermoplastic-matrix composites

    SciTech Connect

    Brady, R.L.

    1989-01-01

    The major theme of this dissertation is structure/property relationships in fiber-reinforced thermoplastic-matrix composites. Effort has been focused on the interface: interfacial crystallization and fiber/matrix adhesion. Included are investigations on interfacial nucleation and morphology, measurement of fiber/matrix adhesion, effects of interfacial adsorption and crystallization on fiber/matrix adhesion, and composites reinforced with thermotropic liquid crystal copolyester fibers. Crystallization of a copolyester and polybutylene terephthalate with glass, carbon, or aramid fibers has been studied with regard to interfacial morphology. Techniques employed included hot-stage optical microscopy and differential scanning calorimetry. Nucleation by the fibers was found to be a general phenomenon. Morphology could be varied by changing the cooling rate. In order to better monitor fiber /matrix adhesion, a buckled plate test has been developed. The test measures transverse toughness as the parameter characterizing interfacial adhesion in unidirectional, continuous-fiber composites. The test is simple to perform yet has advantages over other interfacial evaluation techniques. The buckled plate test was found to be a sensitive measure of fiber/matrix adhesion. The buckled plate test has been used along with the transverse tensile test to examine how interfacial adsorption and crystallization affect fiber/matrix adhesion in polycarbonate/carbon fiber composites. Adsorption was found to be of primary importance in developing adhesion, while crystallization is a secondary effect. The toughness data have been fit successfully for annealing time and temperature dependence. The dependence of adsorption and transverse toughness on matrix molecular weight was found to be large, with higher molecular weights adsorbing more effectively.

  15. Roles of nanofiller structure on mechanical behavior of thermoplastic nanocomposites

    NASA Astrophysics Data System (ADS)

    Weon, Jong Il

    The roles of nanofiller structural parameters, such as filler shape, aspect ratio and orientation, on mechanical properties of thermoplastic nanocomposites have been studied. A commercial grade nylon-6/clay nanocomposite is subjected to a large-scale simple shear orientation process and the resulting morphology is investigated on various length scale levels. Both the orientation and the aspect ratio of nanoclays, which can be altered by the simple shear process, have been studied. The incorporation of well-dispersed nanoclays into the nylon-6 matrix greatly reduces the chain mobility as well as the crystallinity of nylon-6. The exfoliated nanocomposites show that the global orientation of clay layers dictates the orientation of crystalline lamellae. Two types of lamellar orientation are observed, as revealed by small-angle X-ray scattering. One type of lamellae is oriented ˜41° away from the clay surface, whereas the simple shear process induces another weak preferred lamellar orientation nearly perpendicular to the clay surface. The formation of those lamellar orientations appears to be related to both orientation of the clay in the nanocomposite and the simple shear process. It is found that the modulus, strength, and heat distortion temperature of the nanocomposites decrease as the clay aspect ratio and degree of orientation are reduced. The micromechanics-based models accurately describe the relationship between clay structural parameters and the corresponding moduli for exfoliated nanocomposites. The impact fracture mechanisms of polypropylene (PP)-calcium carbonate (CaCO3) nanoparticles have been investigated. A detailed investigation reveals that the CaCO 3 nanoparticles act as stress concentrators to initiate massive crazes, followed by shear banding in the PP matrix.

  16. Microstructural characterization of semi-interpenetrating polymer networks by positron lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh, Jag J.; Pater, Ruth H.; Eftekhari, Abe

    1998-01-01

    Thermoset and thermoplastic polyimides have complementary physical/mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. It is expected that a combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPNs) of thermoset LaRC™-RP46 and thermoplastic LaRC™-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0:100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical/mechanical properties. As expected, positronium atoms are not formed in these samples. The second life time component has been used to infer the positron trap dimensions. The "free volume" goes through a minimum at about 50:50 ratio, suggesting that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples have been discussed in this paper.

  17. Microstructural Characterization of Semi-Interpenetrating Polymer Networks by Positron Lifetime Spectroscopy

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Pater, Ruth H.; Eftekhari, Abe

    1996-01-01

    Thermoset and thermoplastic polyimides have complementary physical and mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. A combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPN) of thermoset LaRC(TM)-RP46 and thermoplastic LaRC(TM)-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0:100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical and mechanical properties. As expected, positronium atoms are not formed in these samples. The second lifetime component has been used to infer the positron trap dimensions. The 'free volume' goes through a minimum at a ratio of about 50:50, and this suggests that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples are discussed.

  18. 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 density, cure behavior, dynamic properties and mechanical properties were measured. Good mechanical properties of revulcanized rubber were achieved by blending devulcanized rubber with the carbon black filled virgin butyl rubber. The structural characteristics of devulcanized butyl rubber were simulated using the Dobson-Gordon theory of rubber network statistics. A fairly good agreement between experimental data and theoretical prediction on normalized gel fraction vs. normalized crosslink density was achieved. The simulation of devulcanized butyl rubber indicated that the rate of crosslink rupture is much higher than that of the main chain.

  19. Laser Transmission Welding of White Thermoplastics with Adapted Wavelengths

    NASA Astrophysics Data System (ADS)

    Mamuschkin, V.; Roesner, A.; Aden, M.

    Different types of laser sources can be used for polymer welding. By the principle of laser transmission welding the wavelength of the laser is one of the most important criteria when selecting a laser source as the optical properties of the polymers are depending on the wavelength. Up to date white material cannot be welded to each other. The results show that by analysis of the optical properties, especially the absorption and the scattering coefficient and adaption of the laser wavelength the process limits can be extended.

  20. Morphological control of inter-penetrating polymer networks

    NASA Technical Reports Server (NTRS)

    Hansen, Marion

    1989-01-01

    Synthetic organic polymer chemistry has been successful in producing composition of matter with thermal oxidation stability and progressively higher glass transition temperatures. In part, this was done by increasing the steric-hindrance of moieties in the chain of a macromolecule. The resulting polymers are usually quite insoluble and produce molten polymers of very high viscosities. These types of polymers are not easily processed into graphite fiber prepregs by melt or solution impregnation methods. Hence, a technological need exists to produce new knowledge of how to produce polymer-fiber composites from this class of polymers. The concept of freeze drying amic-acid prepolymers with reactive thermoplastic was proposed as a research topic for the ASEE/NASA Summer Faculty Program of 1989 as a means of producing polymer-fiber composites. This process scheme has the thermodynamic attribute that the magnitude of phase separation due to differences in solubility of two organic constituents in solution will be greatly reduced by removing a solvent not by evaporation but by sublimation. Progress to date on evaluating this polymer processing concept is briefly outlined.

  1. Functionalization of polymers using an atmospheric plasma jet in a fluidized bed reactor and the impact on SLM-processes

    NASA Astrophysics Data System (ADS)

    Sachs, M.; Schmitt, A.; Schmidt, J.; Peukert, W.; Wirth, K.-E.

    2014-05-01

    In order to improve thermoplastics (e.g. Polyamide, Polypropylene and Polyethylene) for Selective Laser Beam Melting (SLM) processes a new approach to functionalize temperature sensitive polymer powders in a large scale is investigated. This is achieved by combining an atmospheric pressure plasma jet and a fluidized bed reactor. Using pressurized air as the plasma gas, radicals like OH* are created. The functionalization leads to an increase of the hydrophilicity of the treated polymer powder without changing the bulk properties. Using the polymers in a SLM process to build single layers of melted material leads to an improvement of the melted layers.

  2. Functionalization of polymers using an atmospheric plasma jet in a fluidized bed reactor and the impact on SLM-processes

    SciTech Connect

    Sachs, M., E-mail: karl-ernst.wirth@fau.de; Schmitt, A., E-mail: karl-ernst.wirth@fau.de; Schmidt, J., E-mail: karl-ernst.wirth@fau.de; Peukert, W., E-mail: karl-ernst.wirth@fau.de; Wirth, K-E, E-mail: karl-ernst.wirth@fau.de [Institute of Particle Technology, University of Erlangen-Nuremberg (Germany)

    2014-05-15

    In order to improve thermoplastics (e.g. Polyamide, Polypropylene and Polyethylene) for Selective Laser Beam Melting (SLM) processes a new approach to functionalize temperature sensitive polymer powders in a large scale is investigated. This is achieved by combining an atmospheric pressure plasma jet and a fluidized bed reactor. Using pressurized air as the plasma gas, radicals like OH* are created. The functionalization leads to an increase of the hydrophilicity of the treated polymer powder without changing the bulk properties. Using the polymers in a SLM process to build single layers of melted material leads to an improvement of the melted layers.

  3. ENG 4793: Composite Materials and Processes 1 Combining Thermoplastics with

    E-print Network

    Colton, Jonathan S.

    ­ amorphous polymers slightly higher ­ Many injection molded products #12;2 ENG 4793: Composite Materials for injection molding ­ Longer pellets harder to mold and little benefit · Other shapes: ­ Ribbon, Tape, BMC · Injection Molding Limitations - Significant fiber breakage - input: 12 mm fibers - output: 0.5 ­ 3 mm fibers

  4. Space environmental effects on polymer composites: Research needs and opportunities

    NASA Technical Reports Server (NTRS)

    Jang, Bor Z.; Bianchi, J.; Liu, Y. M.; Chang, C. P.

    1993-01-01

    The long-term performance of polymer-based composites in the space environment is discussed. Both thermoset and thermoplastic matrix composites are included in this discussion. Previous efforts on the space environmental effects on composites are briefly reviewed. Focus of this review is placed on the effects of hygrothermal stresses, atomic oxygen, ultraviolet (UV), and space debris/micrometeoroid impacts along with the potential synergism. Potential approaches to estimating the residual strength of polymer composites after exposure to atomic oxygen erosion or space debris/micrometeoroid impact are evaluated. New ground-based data are then utilized to illustrate the effects of atomic oxygen and thermal cycling on the failure behavior of polymer composites. Finally, research needs, challenges, and opportunities in the field of space environmental effects on composite materials are highlighted.

  5. Processing, performance and biodegradability of a thermoplastic aliphatic polyester\\/starch system

    Microsoft Academic Search

    Jo Ann Ratto; Peter J. Stenhouse; Margaret Auerbach; John Mitchell; Richard Farrell

    1999-01-01

    Composites of a biodegradable thermoplastic aliphatic polyester, polybutylene succinate adipate (PBSA), with granular corn starch were investigated for processability, mechanical and thermal properties, and biodegradability. The PBSA\\/starch films were prepared with starch contents of 5%–30% by weight and processed by blown film extrusion. Increasing the starch content led to an increase in modulus and decreases in tensile strength, elongation to

  6. Diaphragm forming of continuous-fiber reinforced thermoplastics suitable for medium-scale production

    SciTech Connect

    Michaeli, W.; Jehrke, M. [Institute of Plastics Processing, Aachen (Germany)

    1993-12-31

    Sheet-form continuous fiber-reinforced thermoplastics can be processed with the diaphragm forming technology. Using a high-temperature resistant rubber diaphragm the cycle-time is reduced to less than two minutes. The consolidated laminate which consists of several thermoplastic prepregs is positioned between two diaphragms. These diaphragms are made out of silicone or fluorine rubber and can be used up to temperatures of 290 C for a long-term. They are clamped in two separate frames which can be closed airtight against each other. After closing the two frames the laminate is evacuated. The prepregs are heated up above the melting temperature of the thermoplastic matrix using a contact heating device. The heated laminate is transferred to the forming unit where air pressure is applied to one side of the diaphragms and the prepregs are formed into the cavity. Complex shaped geometries can be formed because of a homogeneous pressure distribution during processing and the relative thick diaphragms (1 mm) prevent the laminate from wrinkling during forming. After cooling in the cavity the formed part can be demoulded. During the whole process the thermoplastic prepregs stay between the diaphragms.

  7. Preparation, characterization and properties of acid functionalized multi-walled carbon nanotube reinforced thermoplastic polyurethane nanocomposites

    Microsoft Academic Search

    Aruna Kumar Barick; Deba Kumar Tripathy

    2011-01-01

    The multi-walled carbon nanotube (MWNT) reinforced thermoplastic polyurethane (TPU) nanocomposites were prepared through melt compounding method followed by compression molding. The spectroscopic study indicated that a strong interfacial interaction was developed between carbon nanotube (CNT) and the TPU matrix in the nanocomposites. The microscopic observation showed that the CNTs were homogeneously dispersed throughout the TPU matrix well apart from a

  8. Model predictive control of a twin-screw extruder for thermoplastic vulcanizate (TPV) applications

    Microsoft Academic Search

    M. Trifkovic; M. Sheikhzadeh; K. Choo; S. Rohani

    This paper deals with the design and experimental study of a model predictive controller (MPC) for the regulation of the melt temperature (MT) and the motor load (ML) in a pilot plant co-rotating twin-screw extruder for thermoplastic vulcanizate (TPV) applications. It is shown that these two process variables have significant influence on the crosslinking of the rubber chains by initiation

  9. Fuzzy modeling of the relation between components of thermoplastic composites and their mechanical properties

    Microsoft Academic Search

    Zsolt Csaba Johanyak; Andrea Ádám-Major

    2009-01-01

    Thermoplastic composites are widely used in various areas. In several cases their applicability is determined by their mechanical properties that depend on the proper mixing of the component polymeric materials. In this paper two low complexity fuzzy models are presented that have been developed for the prediction of Charpy impact strength and yield strength as a function of the percent

  10. Investigation on the mechanism of aminosilane-mediated bonding of thermoplastics and poly(dimethylsiloxane).

    PubMed

    Sunkara, Vijaya; Cho, Yoon-Kyoung

    2012-12-01

    A possible mechanism for the aminosilane-mediated room-temperature (RT) bonding of thermoplastics and poly(dimethylsiloxane) (PDMS) is presented. The plasma-activated thermoplastic or PDMS substrates were modified with alkoxy silanes having different organo functional groups, and their bonding characteristics were studied. Manual peeling tests revealed that strong bonding was realized only when the silane had a free amino group and at least two alkoxy groups on the silicon. Silanization was carried out in both aqueous and anhydrous conditions; bonding occurred readily at RT in the former case, but a longer incubation time or a higher temperature was needed for the latter. The presence of the silane on the surface was confirmed by contact-angle measurements and UV spectrophotometric, attenuated total reflectance infrared spectroscopic (ATR-IR) and X-ray photoelectron spectroscopic (XPS) analyses. In the case where the aminosilane was deposited from aqueous solution, the amino functionality of the silane-catalyzed siloxane bond formation between the silanol on the modified thermoplastic surface and the silanol of the plasma-activated PDMS. In the case of anhydrous phase deposition, the aminosilane first catalyzed the hydrolysis of the ethoxy groups on the silicon, and then, catalyzed the condensation between the silanol groups of both materials. Shelf life tests of the modified thermoplastics showed that the aminosilane was stable over 2 weeks, and that bonding occurred at RT when the substrates were soaked in water before bonding. PMID:23198791

  11. Process modeling of heat transfer and crystallization in complex shapes thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Saliba, Tony E.; Anderson, David P.; Servais, Ronald A.

    1989-04-01

    Heat transfer and crystallization kinetics during the processing of thermoplastic composite materials are modeled mathematically in order to predict the temperature and degree of crystallinity as a function of position and time. The model can accommodate complex geometries, variable properties as well as a choice of boundary conditions. The model was verified by comparison with experimental results.

  12. Tailoring the Properties of Thermoplastic Polyester to Meet Special Market Needs

    Microsoft Academic Search

    Carl Gottfried

    1983-01-01

    Thermoplastic polyester (PBT) is one of the newest and fastest growing engineering plastics. Introduced in 1969, sales of the resin rose sharply within the first few years as it found utility in various high volume automotive applications such as louvers, body appliques, and high energy ignition components as well as in various electrical and other industry applications. Unlike most new

  13. Preparing composite materials from matrices of processable aromatic polyimide thermoplastic blends

    NASA Technical Reports Server (NTRS)

    Johnston, Norman J. (inventor); St.clair, Terry L. (inventor); Baucom, Robert M. (inventor); Gleason, John R. (inventor)

    1991-01-01

    Composite materials with matrices of tough, thermoplastic aromatic polyimides are obtained by blending semi-crystalline polyimide powders with polyamic acid solutions to form slurries, which are used in turn to prepare prepregs, the consolidation of which into finished composites is characterized by excellent melt flow during processing.

  14. Preparation and characterization of wheat straw fibers for reinforcing application in injection molded thermoplastic composites

    Microsoft Academic Search

    S. Panthapulakkal; A. Zereshkian; M. Sain

    2006-01-01

    The potential of wheat straw fibers prepared by mechanical and chemical processes as reinforcing additives for thermoplastics was investigated. Fibers prepared by mechanical and chemical processes were characterized with respect to their chemical composition, morphology, and physical, mechanical and thermal properties. Composites of polypropylene filled with 30% wheat straw fibers were prepared and their mechanical properties were also evaluated. The

  15. Simulation of Orientation in Injection Molding of High Aspect Ratio Particle Thermoplastic Composites

    E-print Network

    Wapperom, Peter

    Simulation of Orientation in Injection Molding of High Aspect Ratio Particle Thermoplastic-induced orientation of high aspect ratio particles in injection molded composite parts is presented. For a highly; Hele-Shaw approximation; DGFEM; Coupling effect; Injection molding; Composites INTRODUCTION High aspect

  16. Vacuum forming of thermoplastic sheet results in low-cost investment casting patterns

    NASA Technical Reports Server (NTRS)

    Clarke, A. E., Jr.

    1964-01-01

    Vacuum forming of a sheet of thermoplastic material around a mandrel conforming to the shape of the finished object provides a pattern for an investment mold. The thickness of the metal part is determined by the thickness of the plastic pattern.

  17. Fatigue damage model for injection-molded short glass fibre reinforced thermoplastics

    Microsoft Academic Search

    H. Nouri; F. Meraghni; P. Lory

    2009-01-01

    The present paper is a contribution to the phenomenological modelling of fatigue non-linear cumulative diffuse damage in short glass fibre reinforced thermoplastic matrix composites. In such materials, fatigue damage kinetic exhibits three stages, namely: (i) material softening and damage initiation, (ii) coalescence and propagation of micro-cracks and (iii) macroscopic cracks propagation and material failure. The proposed model is built in

  18. 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.

  19. SOLVENTLESS MANUFACTURE OF ARTILLERY PROPELLANT USING THERMOPLASTIC ELASTOMER BINDER, PP-867

    EPA Science Inventory

    Multi-base gun propellant for artillery ammunition creates 0.3 lb of solvent emissions per lb of propellant, and at expected production rates of 3 million lb/yr, this represents the largest source of VOC emissions due to gun propellant production. New thermoplastic elastomer (TP...

  20. Recycling of ligno-cellulosic and polythylene wastes from agricultural operations in thermoplastic composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the US, wood plastic composites (WPC) represent one of the successful markets for natural fiber-filled thermoplastic composites. In the past several years, the availability of good quality wood fiber has been diminishing and prices of wood and plastic have been increasing. Therefore, the vast qua...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the US, wood plastic composites (WPC) represent one of the successful markets for natural fiber-filled thermoplastic composites. In the past several years, the availability of good quality wood fiber has been diminishing and prices of wood and plastic have been increasing. Therefore, the vast qua...

  2. Evaluation of a Thermoplastic Immobilization System for Breast and Chest Wall Radiation Therapy

    SciTech Connect

    Strydhorst, Jared H. [Ottawa Hospital Cancer Centre, Ottawa (Canada); Department of Physics, Carleton University, Ottawa (Canada); Caudrelier, Jean-Michel [Ottawa Hospital Cancer Centre, Ottawa (Canada); Department of Radiology, University of Ottawa, Ottawa (Canada); Clark, Brenda G. [Ottawa Hospital Cancer Centre, Ottawa (Canada); Department of Physics, Carleton University, Ottawa (Canada); Department of Radiology, University of Ottawa, Ottawa (Canada); Montgomery, Lynn A.; Fox, Greg [Ottawa Hospital Cancer Centre, Ottawa (Canada); MacPherson, Miller S., E-mail: mmacpherson@cvh.on.c [Ottawa Hospital Cancer Centre, Ottawa (Canada); Department of Radiology, University of Ottawa, Ottawa (Canada); Department of Radiation Oncology, University of Toronto, Toronto (Canada); Radiation Medicine Program, Princess Margaret Hospital, Toronto (Canada)

    2011-04-01

    We report on the impact of a thermoplastic immobilization system on intra- and interfraction motion for patients undergoing breast or chest wall radiation therapy. Patients for this study were treated using helical tomotherapy. All patients were immobilized using a thermoplastic shell extending from the shoulders to the ribcage. Intrafraction motion was assessed by measuring maximum displacement of the skin, heart, and chest wall on a pretreatment 4D computed tomography, while inter-fraction motion was inferred from patient shift data arising from daily image guidance procedures on tomotherapy. Using thermoplastic immobilization, the average maximum motion of the external contour was 1.3 {+-} 1.6 mm, whereas the chest wall was found to be 1.6 {+-} 1.9 mm. The day-to-day setup variation was found to be large, with random errors of 4.0, 12.0, and 4.5 mm in the left-right, superior-inferior, and anterior-posterior directions, respectively, and the standard deviations of the systematic errors were found to be 2.7, 9.8, and 4.1 mm. These errors would be expected to dominate any respiratory motion but can be mitigated by daily online image guidance. Using thermoplastic immobilization can effectively reduce respiratory motion of the chest wall and external contour, but these gains can only be realized if daily image guidance is used.

  3. Production of natural fiber reinforced thermoplastic composites through the use of polyhydroxybutyrate-rich biomass

    Microsoft Academic Search

    Erik R. Coats; Frank J. Loge; Michael P. Wolcott; Karl Englund; Armando G. McDonald

    2008-01-01

    Previous research has demonstrated that production of natural fiber reinforced thermoplastic composites (NFRTCs) utilizing bacterially-derived pure polyhydroxybutyrate (PHB) does not yield a product that is cost competitive with synthetic plastic-based NFRTCs. Moreover, the commercial production of pure PHB is not without environmental impacts. To address these issues, we integrated unpurified PHB in NFRTC construction, thereby eliminating a significant energy and

  4. PROCESSING AND CHARACTERIZATION OF WELDED BONDS BETWEEN THERMOSET AND THERMOPLASTIC COMPOSITES

    EPA Science Inventory

    To assemble complex structures with short cycle times, the feasibility of welding thermoplastic (TP) to thermoset (TS) composites is demonstrated using a phenomenological approach. The effect of the thermal degradation of the TS composite (AS4/3501-6) on its shear strength is ass...

  5. Thermoplastic Microfluidic Device for On-Chip Purification of Nucleic Acids for Disposable

    E-print Network

    Thermoplastic Microfluidic Device for On-Chip Purification of Nucleic Acids for Disposable)-based isolation of nucleic acids is demonstrated. The plastic chip can function as a disposable sample preparation by this method allowed for successful extraction and elution of nucleic acids in the polymeric microchip

  6. [Laboratory assessment of deformational features in thermoplastic materials for removable dentures].

    PubMed

    Poiurovskaia, I Ia; Sutugina, T F; Babaev, S A; Ron, O S

    2014-01-01

    The paper presents the results of laboratory tests of base thermoplastic materials Acry F711 and Flexi N512 in comparison with the traditional acrylic base material Ftoracs to study their deformational properties when loaded by repetitive forces close to the functional chewing loads. PMID:25588331

  7. Piezoelectric Polymers

    NASA Technical Reports Server (NTRS)

    Harrison, J. S.; Ounaies, Z.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit promising properties; and to discuss key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers. Piezoelectric polymers have been known to exist for more than forty years, but in recent years they have gained notoriety as a valuable class of smart materials.

  8. Coordination polymers

    Microsoft Academic Search

    M. G. Vinogradov; S. V. Vinogradova; Yu. A. Davidovich; V. V. Korshak

    1963-01-01

    1.The properties of the beryllium-containing internal-complex polymer derived from bis-p-acetoacetylphenyl ether were investigated.2.The polymer is stable to heat: appreciable decomposition sets in only after long heating above 280°. The rate and extent of the degradation of the polymer at high temperatures are higher in air than in nitrogen. The internal-complex polymer undergoes no substantial change in properties as a result

  9. High-precision flexible fabrication of tissue engineering scaffolds using distinct polymers

    SciTech Connect

    Wei, Chuang [North Carolina State University; Cai, Lei [ORNL; Sonawane, Bhushan [North Carolina State University; Wang, Shanfeng [ORNL; Dong, Jingyan [North Carolina State University

    2012-01-01

    Three-dimensional porous structures using biodegradable materials with excellent biocompatibility are critically important for tissue engineering applications. We present a multi-nozzle-based versatile deposition approach to flexibly construct porous tissue engineering scaffolds using distinct polymeric biomaterials such as thermoplastic and photo-crosslinkable polymers. We first describe the development of the deposition system and fabrication of scaffolds from two types of biodegradable polymers using this system. The thermoplastic sample is semi-crystalline poly({var_epsilon}-caprolactone) (PCL) that can be processed at a temperature higher than its melting point and solidifies at room temperature. The photo-crosslinkable one is polypropylene fumarate (PPF) that has to be dissolved in a reactive solvent as a resin for being cured into solid structures. Besides the direct fabrication of thermoplastic PCL scaffolds, we specifically develop a layer molding approach for the fabrication of crosslinkable polymers, which traditionally can only be fabricated by stereolithography. In this approach, a thermoplastic supporting material (paraffin wax) is first deposited to make a mold for each specific layer, and then PPF is deposited on demand to fill the mold and cured by the UV light. The supporting material can be removed to produce a porous scaffold of crosslinked PPF. Both PCL and crosslinked PPF scaffolds fabricated using the developed system have been characterized in terms of compressive mechanical properties, morphology, pore size and porosity. Mouse MC3T3-E1 pre-osteoblastic cell studies on the fabricated scaffolds have been performed to demonstrate their capability of supporting cell proliferation and ingrowth, aiming for bone tissue engineering applications.

  10. Transparent Large Strain Thermoplastic Polyurethane Magneto-Active Nanocomposites

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Carpen, Ileana; Peck, John; Sola, Francisco; Bail, Justin; Lerch, Bradley; Meador, Michael

    2010-01-01

    Smart adaptive materials are an important class of materials which can be used in space deployable structures, morphing wings, and structural air vehicle components where remote actuation can improve fuel efficiency. Adaptive materials can undergo deformation when exposed to external stimuli such as electric fields, thermal gradients, radiation (IR, UV, etc.), chemical and electrochemical actuation, and magnetic field. Large strain, controlled and repetitive actuation are important characteristics of smart adaptive materials. Polymer nanocomposites can be tailored as shape memory polymers and actuators. Magnetic actuation of polymer nanocomposites using a range of iron, iron cobalt, and iron manganese nanoparticles is presented. The iron-based nanoparticles were synthesized using the soft template (1) and Sun's (2) methods. The nanoparticles shape and size were examined using TEM. The crystalline structure and domain size were evaluated using WAXS. Surface modifications of the nanoparticles were performed to improve dispersion, and were characterized with IR and TGA. TPU nanocomposites exhibited actuation for approximately 2wt% nanoparticle loading in an applied magnetic field. Large deformation and fast recovery were observed. These nanocomposites represent a promising potential for new generation of smart materials.

  11. Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method

    SciTech Connect

    Burat, Firat; Gueney, Ali [Istanbul Technical University, Faculty of Mines, Mineral Processing Engineering Department, 34469 Maslak, Istanbul (Turkey); Olgac Kangal, M. [Istanbul Technical University, Faculty of Mines, Mineral Processing Engineering Department, 34469 Maslak, Istanbul (Turkey)], E-mail: kangal@itu.edu.tr

    2009-06-15

    More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste polymers cause serious environmental problems. Burning polymers for recycling is not practiced since poisonous gases are released during the burning process. Particularly, polyvinyl chloride (PVC) materials among waste polymers generate hazardous HCl gas, dioxins containing Cl, etc., which lead to air pollution and shorten the life of the incinerator. In addition, they make other polymers difficult to recycle. Both polyethylene terephthalate (PET) and PVC have densities of 1.30-1.35 g/cm{sup 3} and cannot be separated using conventional gravity separation techniques. For this reason, polymer recycling needs new techniques. Among these techniques, froth flotation, which is also used in mineral processing, can be useful because of its low cost and simplicity. The main objective of this research is to recycle PET and PVC selectively from post-consumer polymer wastes and virgin polymers by using froth flotation. According to the results, all PVC particles were floated with 98.8% efficiency in virgin polymer separation while PET particles were obtained with 99.7% purity and 57.0% efficiency in post-consumer polymer separation.

  12. Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method.

    PubMed

    Burat, Firat; Güney, Ali; Olgaç Kangal, M

    2009-06-01

    More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste polymers cause serious environmental problems. Burning polymers for recycling is not practiced since poisonous gases are released during the burning process. Particularly, polyvinyl chloride (PVC) materials among waste polymers generate hazardous HCl gas, dioxins containing Cl, etc., which lead to air pollution and shorten the life of the incinerator. In addition, they make other polymers difficult to recycle. Both polyethylene terephthalate (PET) and PVC have densities of 1.30-1.35g /cm(3) and cannot be separated using conventional gravity separation techniques. For this reason, polymer recycling needs new techniques. Among these techniques, froth flotation, which is also used in mineral processing, can be useful because of its low cost and simplicity. The main objective of this research is to recycle PET and PVC selectively from post-consumer polymer wastes and virgin polymers by using froth flotation. According to the results, all PVC particles were floated with 98.8% efficiency in virgin polymer separation while PET particles were obtained with 99.7% purity and 57.0% efficiency in post-consumer polymer separation. PMID:19155169

  13. Functionalized Materials From Elastomers to High Performance Thermoplastics

    SciTech Connect

    Laura Ann Salazar

    2003-05-31

    Synthesis and incorporation of functionalized materials continues to generate significant research interest in academia and in industry. If chosen correctly, a functional group when incorporated into a polymer can deliver enhanced properties, such as adhesion, water solubility, thermal stability, etc. The utility of these new materials has been demonstrated in drug-delivery systems, coatings, membranes and compatibilizers. Two approaches exist to functionalize a material. The desired moiety can be added to the monomer either before or after polymerization. The polymers used range from low glass transition temperature elastomers to high glass transition temperature, high performance materials. One industrial example of the first approach is the synthesis of Teflon(reg. sign). Poly(tetrafluoroethylene) (PTFE or Teflon(reg. sign)) is synthesized from tetrafluoroethylene, a functionalized monomer. The resulting material has significant property differences from the parent, poly(ethylene). Due to the fluorine in the polymer, PTFE has excellent solvent and heat resistance, a low surface energy and a low coefficient of friction. This allows the material to be used in high temperature applications where the surface needs to be nonabrasive and nonstick. This material has a wide spread use in the cooking industry because it allows for ease of cooking and cleaning as a nonstick coating on cookware. One of the best examples of the second approach, functionalization after polymerization, is the vulcanization process used to make tires. Natural rubber (from the Hevea brasiliensis) has a very low glass transition temperature, is very tacky and would not be useful to make tires without synthetic alteration. Goodyear's invention was the vulcanization of polyisoprene by crosslinking the material with sulfur to create a rubber that was tough enough to withstand the elements of weather and road conditions. Due to the development of polymerization techniques to make cis-polyisoprene, natural rubber is no longer needed for the manufacturing of tires, but vulcanization is still utilized.

  14. Extrusion foaming of thermoplastic cellulose acetate from renewable resources using a two-component physical blowing agent system

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Windeck, C.; Hendriks, S.; Zepnik, S.; Wodke, T.

    2014-05-01

    Thermoplastic cellulose acetate (CA) is a bio-based polymer with optical, mechanical and thermal properties comparable to those of polystyrene (PS). The substitution of the predominant petrol-based PS in applications like foamed food trays can lead to a more sustainable economic practice. However, CA is also suitable for more durable applications as the biodegradability rate can be controlled by adjusting the degree of substitutions. The extrusion foaming of CA still has to overcome certain challenges. CA is highly hydrophilic and can suffer from hydrolytic degradation if not dried properly. Therefore, the influence of residual moisture on the melt viscosity is rather high. Beyond, the surface quality of foam CA sheets is below those of PS due to the particular foaming behaviour. This paper presents results of a recent study on extrusion foamed CA, using a two-component physical blowing agent system compromising HFO 1234ze as blowing agent and organic solvents as co-propellant. Samples with different co-propellants are processed on a laboratory single screw extruder at IKV. Morphology and surface topography are investigated with respect to the blowing agent composition and the die pressure. In addition, relationships between foam density, foam morphology and the propellants are analysed. The choice of the co-propellant has a significant influence on melt-strength, foaming behaviour and the possible blow-up ratio of the sheet. Furthermore, a positive influence of the co-propellant on the surface quality can be observed. In addition, the focus is laid on the effect of external contact cooling of the foamed sheets after the die exit.

  15. Natural Polymers

    NSDL National Science Digital Library

    David Teegarden

    2004-01-01

    Polymers that exist in nature, called biopolymers , include a large and diverse range of compounds. This chapter discusses the most important types of natural polymers--their chemical makeup, key properties, and where they are found. The focus will be more on the chemical and physical properties of natural polymers and less on their biological synthesis or physiological function. The references at the end of the chapter provide additional information.

  16. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  17. A study on thermal properties of biodegradable polymers using photothermal methods

    NASA Astrophysics Data System (ADS)

    Siqueira, A. P. L.; Poley, L. H.; Sanchez, R.; da Silva, M. G.; Vargas, H.

    2005-06-01

    In this work is reported the use of photothermal techniques applied to the thermal characterization of biodegradable polymers of Polyhydroxyalkanoates (PHAs) family. This is a family of polymer produced by bacteria using renewable resources. It exhibits thermoplastic properties and therefore it can be an alternative product for engineering plastics, being also applied as packages for food industry and fruits. Thermal diffusivities were determined using the open photoacoustic cell (OPC) configuration. Specific heat capacity measurements were performed monitoring temperature of the samples under white light illumination against time. Typical values obtained for the thermal properties are in good agreement with those found in the literature for other polymers. Due to the incorporation of hydroxyvalerate in the monomer structure, the thermal diffusivity and thermal conductivity increase reaching a saturation value, otherwise the specific thermal capacity decreases as the concentration of the hydroxyvalerate (HV) increases. These results can be explained by polymers internal structure and are allowing new applications of these materials.

  18. ["Elastic osteosynthesis" with autocompression plates of carbon fiber reinforced thermoplastic material].

    PubMed

    Stange, J; Mittelmeier, H

    1989-06-01

    The problem of atrophic bone that occurs in osteosynthesis employing rigid plates is first depicted. Attempts at fabricating "simirigid" plates, which, however, have so far failed to gain any practical importance are then discussed. The reason for this seems to be that made of duroplastics cannot be molded during the operation and the thermoplastics do not have sufficient strength. The production of semirigid plates made of thermoplastic Polyethersulfon (PES), reinforced with 20% short carbon fibres, results in plates which are made moldable by heating in a small oven, white retaining sufficient static strength, although only limited fatigue strength. Biomechanical examinations revealed that with appropriate dimensioning of the plates, "elastic osteosynthesis" results in less loss of mechanical function of the stabilized bones, so that less atrophy of the bone may be expected. During more pronounced exercise loading, a reversible "springiness" of the fracture results, which might stimulate callus formation and improved stability. PMID:2758100

  19. Simulation of Light Propagation within Glass Fiber Filled Thermoplastics for Laser Transmission Welding

    NASA Astrophysics Data System (ADS)

    Hohmann, Martin; Devrient, Martin; Klämpfl, Florian; Roth, Stephan; Schmidt, Michael

    Laser transmission welding is a well-known joining technology for thermoplastics. Because of the needs of lightweight, cost effective and green production nowadays injection molded parts usually have to be welded. These parts are made out of semi-crystalline thermoplastics which are filled to a high amount with glass fibers. This leads to higher absorption and more scattering within the upper joining partner and hasa negative influence onto the welding process. Here a ray tracing model capable of considering every single glass fiber is introduced. Hence spatially not equally distributed glass fibers can be taken into account. Therefore the model is able to calculate in detail the welding laser intensity distribution after transmission through the upper joining partner. Data gained by numerical simulation is compared to data obtained by laser radiation scattering experiments. Thus observed deviation is quantified and discussed.

  20. 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.

  1. Thermoplastic Mask Influence with High Energy Electron Radiotherapy Evaluated by the Fricke Xylenol Gel Chemical Dosimeter

    NASA Astrophysics Data System (ADS)

    Moreira, M. V.; Petchevist, P. C. D.; de Almeida, A.

    2009-03-01

    A thermoplastic mask is used to immobilize the patient head during radiotherapy. It also enhances the absorbed dose distribution improving the radiotherapic treatment. In this work we investigate the influence of the thermoplastic material in the phantom surface and in the target volume region. For the measurements a Fricke Xylenol Gel dosimeter, based on Fe (II) to Fe (III) oxidation, was used and their values compared with those from a 0.055 cm3 PTW/Markus Parallel Plate Ionization Chamber. From the results we could infer the absorbed dose distribution as a function of depth in the water phantom from the surface up to the build-up depth for electron beam energies of 5, 8 and 10 MeV. The results show that using the mask, the surface dose distribution is not significantly alterated, and we therefore conclude that the mask is recommended and useful in head and neck cancer treatments.

  2. Dependence of Mechanical and Thermal Properties of Thermoplastic Composites on Electron Beam Irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Sok Won; Park, K.; Lee, S. H.; Kang, J. S.; Kang, K. H.

    2007-06-01

    Since the restrictions for environmental protection being strengthened, thermoplastics reinforced with natural fibers (NF’s), such as jute, kenaf, flax, etc. have appeared as alternatives to chemical plastics for automobile interior materials. In this study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composed of 50% polypropylene (PP) and 50% natural fiber (NF) irradiated by an electron beam (energy: 0.5 MeV, dose: 0 20 kGy) were measured. The length and thickness of PP and NF are 80 ± 10 mm and 40 120 ?m, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum, when the dose of the electron beam was 10 kGy. However, the effect of the dose on the deformation was not clear.

  3. Mechanical and thermal properties of thermoplastic acetylated starch\\/poly(ethylene- co-vinyl alcohol) blends

    Microsoft Academic Search

    Wenbo Jiang; Xiuying Qiao; Kang Sun

    2006-01-01

    Blends of thermoplastic acetylated starch (TPAS) and poly(ethylene-co-vinyl alcohol) (EVOH) were prepared with different components by melt blending method and the mechanical and thermal properties of these blends were investigated. Tensile testing shows that with the increasing of EVOH content, the mechanical properties of TPAS\\/EVOH blends are improved significantly. Dynamic mechanical analysis (DMA) indicates that there is a good miscibility

  4. Reduction of the free-edge effect in fibre-reinforced thermoplastic laminates by localized reconsolidation

    Microsoft Academic Search

    W. J. Unger; J. S. Hansen

    1992-01-01

    A thermal process is described for application to graphite-fiber reinforced PEEK thermoplastic laminates which reduces the free-edge effect and thereby improves static and fatigue strength. This process, referred to as localized reconsolidation, involves heating a fracture-critical free-edge to above its melt temperature while under pressure and then cooling the area at a specified rate. This process reduces residual stresses and

  5. Current leakage prevention in resistance welding of carbon fibre reinforced thermoplastics

    Microsoft Academic Search

    M. Dubé; P. Hubert; A. Yousefpour; J. Denault

    2008-01-01

    Current leakage is a concern with resistance welding of carbon fibre reinforced thermoplastic composites. This phenomenon is particularly important when unidirectional adherends, with the carbon fibres parallel to the electrical current direction, are welded. In this investigation, a new electrically-insulated heating element consisting of a ceramic-coated (TiO2) stainless steel mesh was developed to prevent current leakage. Special specimen geometry, called

  6. Fatigue failure characterisation of resistance-welded thermoplastic composites skin\\/stringer joints

    Microsoft Academic Search

    M. Dubé; P. Hubert; A. Yousefpour; J. Denault

    2009-01-01

    An experimental investigation characterising the fatigue failure mechanisms of resistance-welded thermoplastic composites skin\\/stringer joints is presented. Unidirectional (UD) and quasi-isotropic adherends were welded using stainless steel meshes as heating elements. The specimen geometry consisted of a flange laminate, representing a stringer, welded onto a skin laminate. In order to avoid current leakage to the electrically conductive adherends, a ceramic-coated heating

  7. Reduction of Noise from Disc Brake Systems Using Composite Friction Materials Containing Thermoplastic Elastomers (TPEs)

    Microsoft Academic Search

    Mohsen Masoomi; Ali Asghar Katbab; Hossein Nazockdast

    2006-01-01

    Attempts have been made for the first time to prepare a friction material with the characteristic of thermal sensitive modulus, by the inclusion of thermoplastic elastomers (TPE) as viscoelastic polymeric materials into the formulation in order to the increase the damping behavior of the cured friction material. Styrene–butadiene–styrene (SBS), styrene–ethylene–butylene–styrene (SEBS) and nitrile rubber\\/polyvinyl chloride (NBR\\/PVC) blend system were used

  8. Long term acid rain multistress performance of Thermoplastic and thermoset polymeric insulators

    Microsoft Academic Search

    Raji Sundararajan

    2010-01-01

    Rain with a pH <; 5.6 is known as acid rain. Acid rain can deteriorate high voltage outdoor polymeric insulators and affect their performance over time. Presented in this paper are the results of a long term (2544h) performance study of 28kV Thermoplastic elastomeric (TPE) and silicone rubber (thermoset) insulators under acid rain multistress conditions of Mexico City, Mexico. The

  9. Thermoplastic polyurethane—The material used for the erlanger silver catheter

    Microsoft Academic Search

    T. Hentschel; H. Münstedt

    1999-01-01

    Summary  The Erlanger silver catheter consists of a thermoplastic polyurethane elastomer (TPU). To achieve an antimicrobial effect,\\u000a silver particles at a concentration of 0.5–1.0% by weight are incorporated into the basic material. The good mechanical properties\\u000a were shown to remain present after the incorporation of the silver. The characteristic mechanical data of blends made of a\\u000a soft and a hard TPU

  10. Electric and magnetic properties of a thermoplastic elastomer incorporated with ferromagnetic powders

    Microsoft Academic Search

    H. S. Gokturk; Thomas J. Fiske; Dilhan M. Kalyon

    1993-01-01

    The electric and magnetic properties of a composite material consisting of a thermoplastic elastomer incorporated with iron powder and nickel-iron alloy powder are investigated. The volume fraction of the powder filters ranges from 0.1 to 0.5. The composites are characterized in terms of their volume and surface resistivities, permittivities and electric loss factors and magnetic permeabilities 0 and magnetic loss

  11. Injection Molded Optical Lens Using a Heat Resistant Thermoplastic Resin with Electron Beam Cross-Linking

    NASA Astrophysics Data System (ADS)

    Tomomi Sano,; Yoshitomo Iyoda,; Takayuki Shimazu,; Michiko Harumoto,; Akira Inoue,; Makoto Nakabayashi,; Hiroshi Ito,

    2010-05-01

    The poor heat resistant properties of a transparent thermoplastic resin was improved by electron beam irradiation cross-linking. A correcting aspheric lens for a 635-nm laser diode was fabricated using an injection molding machine, and was irradiated with an electron beam. The near field pattern (NFP), the far field pattern (FFP) at the focus position and the transmittance of the lens did not change after exposure to a 260 °C reflow process for 60 s.

  12. Adhesion of nickel–titanium shape memory alloy wires to thermoplastic materials: theory and experiments

    Microsoft Academic Search

    F C Antico; P D Zavattieri; L G Hector Jr; A Mance; W R Rodgers; D A Okonski

    2012-01-01

    We present a combined experimental\\/theoretical study aimed at enhancing adhesion between a NiTi wire and a thermoplastic polyolefin (TPO) matrix in which it is embedded. NiTi wire surfaces were subjected to the following surface treatments prior to pull-out tests: (i) treatment with an acid etch or chemical conversion coating and (ii) application of a surface microgeometry to enhance mechanical interlocking

  13. Sol–gel based fabrication of hybrid microfluidic devices composed of PDMS and thermoplastic substrates

    Microsoft Academic Search

    Yusuke Suzuki; Masumi Yamada; Minoru Seki

    2010-01-01

    Fabrication of microfluidic devices using both rigid and flexible plastic substrates offers benefits for making pressure-actuated membrane valves, mechanically active components, and low-cost but highly functional 3D microchannel networks. Here we present a simple and versatile process for bonding flexible polydimethylsiloxane (PDMS) and rigid thermoplastics like poly(methyl methacrylate) (PMMA), by utilizing the sol–gel method. The silica sol, obtained by oligomerizing

  14. Polymers All Around You!

    ERIC Educational Resources Information Center

    Gertz, Susan

    Background information on natural polymers, synthetic polymers, and the properties of polymers is presented as an introduction to this curriculum guide. Details are provided on the use of polymer products in consumer goods, polymer recycling, polymer densities, the making of a polymer such as GLUEP, polyvinyl alcohol, dissolving plastics, polymers

  15. Biodegradable thermoplastic composites based on polyvinyl alcohol and algae.

    PubMed

    Chiellini, Emo; Cinelli, Patrizia; Ilieva, Vassilka I; Martera, Martina

    2008-03-01

    Algae constitute a largely available, low value material from renewable resources of marine origin to be used for the production of eco-compatible composites. Fibers of the green alga Ulva armoricana from the French coast were positively evaluated for the production of composites with a hydrophilic, eco-compatible polymer, such as poly(vinyl alcohol) (PVA) as continuous matrix by casting of aqueous suspensions and compression molding. PVA, Ulva, and starch were also successfully processed by the melt in the presence of glycerol. Positive results were obtained for film-forming properties and mechanical characteristics also with limited amounts of PVA (40%) attesting for Ulva suitability to be introduced in composites (up to 30%). Degradation in soil of Ulva and an Ulva-based composites outlined a rapid mineralization of Ulva in the selected medium (over 80% in 100 days) while the composite samples underwent a mineralization rate affected by the different component propensity to degradation. PMID:18257530

  16. Predicting fill patterns for the in-mould coating process for thermoplastic parts

    NASA Astrophysics Data System (ADS)

    Chen, Xu; Bhagavatula, Narayan; Castro, Jose M.

    2004-05-01

    In-mould coating (IMC) is an environmentally friendly alternative to painting for injection moulded plastic parts. IMC is carried out by injecting a liquid low viscosity thermoset material onto the surface of the thermoplastic substrate while it is still in the mould. The coating then solidifies and adheres to the substrate. The IMC process is being integrated with conventional thermoplastic injection moulding to improve the part surface quality and to protect it from outdoor exposure. In a previous paper, we presented a Hele-Shaw based mathematical model to simulate the coating flow during the IMC process assuming the coating to be a Newtonian fluid. It has been shown that the coating behaves like a shear thinning fluid. In this paper, a power-law viscosity model is employed to describe the rheological behaviour of the coating material. The continuous deformation of the thermoplastic substrate caused by the coating injection is analysed by means of the PVT relationship of the substrate. The corresponding model is solved using the control volume based finite element method to predict the fill pattern and pressure distribution during the coating flow. The predicted results are compared to experimentally obtained fill patterns. The need to include the 'edge effect' is also discussed.

  17. Long-Fiber Thermoplastic Injection Molded Composites: from Process Modeling to Property Prediction

    SciTech Connect

    Nguyen, Ba Nghiep; Holbery, Jim D.; Johnson, Kenneth I.; Smith, Mark T.

    2005-09-01

    Recently, long-fiber filled thermoplastics have become a great interest to the automotive industry since these materials offer much better property performance (e.g. elastic moduli, strength, durability…) than their short-fiber analogues, and they can be processed through injection molding with some specific tool design. However, in order that long-fiber thermoplastic injection molded composites can be used efficiently for automotive applications, there is a tremendous need to develop process and constitutive models as well as computational tools to predict the microstructure of the as-formed composite, and its resulting properties and macroscopic responses from processing to the final product. The microstructure and properties of such a composite are governed by i) flow-induced fiber orientation, ii) fiber breakage during injection molding, and iii) processing conditions (e,g. pressure, mold and melt temperatures, mold geometries, injection speed, etc.). This paper highlights our efforts to address these challenging issues. The work is an integrated part of a research program supported by the US Department of Energy, which includes • The development of process models for long-fiber filled thermoplastics, • The construction of an interface between process modeling and property prediction as well as the development of new constitutive models to perform linear and nonlinear structural analyses, • Experimental characterization of model parameters and verification of the model predictions.

  18. Characterization of carbon-fiber reinforced polyetherimide thermoplastic composites using mechanical and ultrasonic methods

    NASA Astrophysics Data System (ADS)

    ALHaidri, Mohannad

    Continuous fiber-reinforced thermoplastics (CFRT) have the potential for being a mass-produced material for high-performance applications. The primary challenge of using CFRT is achieving fiber wet-out due to the high viscosity of thermoplastics. This results in higher temperatures and pressures required for processing the composites. Co-mingling thermoplastic fibers with a reinforcing fiber, potentially, can enable better wetting by reducing the distance the matrix needs to flow. This could result in shorter cycle times and better consolidation at lower temperatures and pressures. In this study, a polyetherimide (PEI) fiber was comingled with carbon fibers (CF). The resultant fibers were woven into fabrics and processed through a compression-molding technique to form laminates. Control specimens were also fabricated using films of PEI layered between plies of woven carbon-fiber materials. The manufactured CFRT panels were evaluated using ultrasonic C-scans (scans in two spatial dimensions) and then characterized for mechanical properties. The specimens produced using the co-mingled fibers had the cycle time reduced significantly compared to the film CFRT, although the results from the mechanical property evaluations were mixed. The behaviors in the co-mingled laminates can be attributed to the resin- and void-content distribution and the fiber-bundle orientations in the cured composite.

  19. Fabrication and characterization of thermoplastic elastomer dry adhesives with high strength and low contamination.

    PubMed

    Bin Khaled, Walid; Sameoto, Dan

    2014-05-14

    Polydimethylsiloxane (PDMS) and polyurethane elastomers have commonly been used to manufacture mushroom shaped gecko-inspired dry adhesives with high normal adhesion strength. However, the thermosetting nature of these two materials severely limits the commercial viability of their manufacturing due to long curing times and high material costs. In this work, we introduce poly(styrene-ethylene/butylene-styrene) (SEBS) thermoplastic elastomers as an alternative for the manufacture of mushroom shaped dry adhesives with both directional and nondirectional performance. These materials are attractive for their potential to be less contaminating via oligomer transfer than thermoset elastomers, as well as being more suited to mass manufacturing. Low material transfer properties are attractive for adhesives that could potentially be used in cleanroom environments for microscale assembly and handling in which device contamination is a serious concern. We characterized a thermoplastic elastomer in terms of oligomer transfer using X-ray photoelectron spectroscopy and found that the SEBS transfers negligible amounts of its own oligomers, during contact with a gold-coated silicon surface, which may be representative of the metallic bond pads found in micro-electro-mechanical systems devices. We also demonstrate the fabrication of mushroom shaped isotropic and anisotropic adhesive fibers with two different SEBS elastomer grades using thermocompression molding and characterize the adhesives in terms of their shear-enhanced normal adhesion strength. The overall adhesion of one of the thermoplastic elastomer adhesives was found to be stronger or comparable to their polyurethane counterparts with identical dimensions. PMID:24712514

  20. 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. PMID:18572622

  1. Multiple-objective optimization in precision laser cutting of different thermoplastics

    NASA Astrophysics Data System (ADS)

    Tamrin, K. F.; Nukman, Y.; Choudhury, I. A.; Shirley, S.

    2015-04-01

    Thermoplastics are increasingly being used in biomedical, automotive and electronics industries due to their excellent physical and chemical properties. Due to the localized and non-contact process, use of lasers for cutting could result in precise cut with small heat-affected zone (HAZ). Precision laser cutting involving various materials is important in high-volume manufacturing processes to minimize operational cost, error reduction and improve product quality. This study uses grey relational analysis to determine a single optimized set of cutting parameters for three different thermoplastics. The set of the optimized processing parameters is determined based on the highest relational grade and was found at low laser power (200 W), high cutting speed (0.4 m/min) and low compressed air pressure (2.5 bar). The result matches with the objective set in the present study. Analysis of variance (ANOVA) is then carried out to ascertain the relative influence of process parameters on the cutting characteristics. It was found that the laser power has dominant effect on HAZ for all thermoplastics.

  2. Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment.

    PubMed

    Fang, Dongyu; Zhang, Ning; Chen, Hui; Bai, Yuxing

    2013-11-30

    Mechanical properties are crucial for screening orthodontic thermoplastic materials for invisible aligners. However, most of previous studies were carried out within laboratory conditions which limit our understanding of the mechanical behaviors of aligners within oral environment. In this study, we studied the dynamic stress relaxation of thermoplastic materials by combination of Bose ElectroForce and a homemade temperature-controlled water bath. The 3-h stress relaxation curves of five orthodontic thermoplastic materials were measured within 37°C water bath as well as comparatively in ambient atmospheric environment (~20°C). The percentage residual stress at 0, 30, 60, 90, 120, 150, and 180 min was selected for statistical analyses. As expected, the experimental results showed that the residual stress within all five materials decreased with time, and that this process was significantly accelerated in the 37°C water bath (p<0.05). Compared with other materials, Erkodur and Masel exhibited slower relaxing rates in the 37°C water bath (p<0.05). PMID:24240895

  3. Single-Walled Carbon Nanotube / Semicrystalline Polymer Composite Fibers

    NASA Astrophysics Data System (ADS)

    Haggenmueller, Reto; Fischer, John E.; Winey, Karen I.

    2002-03-01

    Single-walled carbon nanotubes (SWNTs) have demonstrated far superior mechanical, thermal and electrical properties relative to carbon fibers. Similar properties are expected for polymer/SWNT nanocomposites. We have produced SWNT-thermoplastic composites with extraordinary alignment of the nanotubes via melt processing followed by fiber melt spinning. The improved mechanical properties depend on the alignment of the nanotubes, which is controlled by the draw ratio of the composite fibers. Alignment of the nanotubes seems to reduce the electrical conductivity, because the percolation threshold of the one-dimensional conductors is reduced for straight, aligned nanotubes. Semicrystalline polyethylene and various nylons are used as the matrix and the mechanical, electrical properties are measured. The effect of the nanotubes on the crystallinity and the melting point are determined. A key factor of the composite performance is the dispersion of the nanotubes in the polymer matrix, the characterization of which is explored.

  4. Tough, processable semi-interpenetrating polymer networks from monomer reactants

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (inventor)

    1994-01-01

    A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance, and mechanical performance, when compared to the commercial Thermid materials. This simultaneous semi-IPN was prepared by mixing the monomer precursors of Thermid AL-600 (a thermoset) and NR-150B2 (a thermoplastic) and allowing the monomers to react randomly upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene end-capped polyimides which were previously inherently brittle and difficult to process.

  5. Polymer powder prepregging: Scoping study

    NASA Technical Reports Server (NTRS)

    Throne, James L.

    1988-01-01

    Early on, it was found that NEAT LARC-TPI thermoplastic polyimide powder behaved elastoplastically at pressures to 20 ksi and temperatures to 260 degrees celcius (below MP). At high resin assay, resin powder could be continuously cold-flowed around individual carbon fibers in a metal rolling mill. At low resin assay (2:1, C:TPI), fiber breakage was prohibitive. Thus, although processing of TPI below MP would be quite unique, it appears that the polymer must be melted and flowed to produce low resin assay prepreg. Fiber tow was spread to 75 mm using a venturi slot tunnel. This allowed intimate powder/fiber interaction. Two techniques were examined for getting room temperature powder onto the room temperature fiber surface. Electrostatic powder coating allows the charged powder to cling tenaciously to the fiber, even while heated with a hot air gun to above its melt temperature. A variant of the wet slurry coating process was also explored. The carbon fibers are first wetted with water. Then dry powder is sprinkled onto the wet tow and doctor-rolled between the fibers. The wet structure is then taken onto a heated roll, with hot air guns drying and sinter-melting the powder onto the fiber surfaces. In both cases SEM shows individual fibers coated with powder particles that have melted in place and flowed along the fiber surface via surface tension.

  6. Polymers Guide

    NSDL National Science Digital Library

    This 21 page document contains an instructor guide for the polymers module from Nano-Link. The activity requires a background in eight grade science. The document includes background information on polymers, a hands-on learning activity, questions to check understanding, links to multimedia resources, and further readings. Visitors must complete a quick and free registration to access the materials.

  7. Polymers & People

    ERIC Educational Resources Information Center

    Lentz, Linda; Robinson, Thomas; Martin, Elizabeth; Miller, Mary; Ashburn, Norma

    2004-01-01

    Each Tuesday during the fall of 2002, teams of high school students from three South Carolina counties conducted a four-hour polymer institute for their peers. In less than two months, over 300 students visited the Charleston County Public Library in Charleston, South Carolina, to explore DNA, nylon, rubber, gluep, and other polymers. Teams of…

  8. Shock, release and Taylor impact of the semicrystalline thermoplastic polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Bourne, N. K.; Brown, E. N.; Millett, J. C. F.; Gray, G. T.

    2008-04-01

    The high strain-rate response of polymers is a subject that has gathered interest over recent years due to their increasing engineering importance, particularly in load bearing applications subject to extremes of pressure and strain rate. The current work presents two specific sets of experiments interrogating the effect of dynamic, high-pressure loading in the regime of the phase II to phase III pressure-induced crystalline phase transition in polytetrafluoroethylene (PTFE). These are gas-gun driven plate- and Taylor impact. Together these experiments highlight several effects associated with the dynamic, pressure-induced phase transitions in PTFE. An elevated release wave speed shows evidence of a pressure-induced phase change at a stress commensurate with that observed statically. It is shown that convergence between analytic derivations of release wave speed and the data requires the phase II to III transition to occur. Taylor impact is an integrated test that highlights continuum behavior that has origin in mesoscale response. There is a rapid transition from ductile to brittle behavior observed that occurs at a pressure consistent with this phase transition.

  9. Toughening mechanisms in interfacially modified HDPE/thermoplastic starch blends.

    PubMed

    Taguet, Aurélie; Bureau, Martin N; Huneault, Michel A; Favis, Basil D

    2014-12-19

    The mechanical behavior of polymer blends containing 80 wt% of HDPE and 20 wt% of TPS and compatibilized with HDPE-g-MA grafted copolymer was investigated. Unmodified HDPE/TPS blends exhibit high fracture resistance, however, the interfacial modification of those blends by addition of HDPE-g-MA leads to a dramatic drop in fracture resistance. The compatibilization of HDPE/TPS blends increases the surface area of TPS particles by decreasing their size. It was postulated that the addition of HDPE-g-MA induces a reaction between maleic anhydride and hydroxyl groups of the glycerol leading to a decrease of the glycerol content in the TPS phase. This phenomenon increases the stiffness of the modified TPS particles and stiffer TPS particles leading to an important reduction in toughness and plastic deformation, as measured by the EWF method. It is shown that the main toughening mechanism in HDPE/TPS blends is shear-yielding. This article demonstrates that stiff, low diameter TPS particles reduce shear band formation and consequently decrease the resistance to crack propagation. PMID:25263885

  10. Structure development during flow of ternary blends of a polyamide (nylon 66), a thermotropic liquid crystalline polymer (poly(ester amide)) and a functionalized polypropylene

    Microsoft Academic Search

    Yongsok Seo; Byeongyeol Kim; Kwang Ung Kim

    1999-01-01

    It is shown that a fibril structure of a thermotropic liquid crystalline polymer (TLCP)(poly(ester amide)) can be developed in the shear flow field of a thermoplastic matrix (polyamide, nylon 66) when the viscosity of the latter is lower than that of the former. The addition of a third component, a functionalized polypropylene (maleic-anhydride-grafted polypropylene, MA-PP) that interacts with both the

  11. Multiscale simulation of polymer nano-composites (PNC) using molecular dynamics (MD) and generalized interpolation material point method (GIMP)

    NASA Astrophysics Data System (ADS)

    Nair, Abilash R.

    Recent mechanical characterization experiments with pultruded E-Glass / polypropylene (PP) and compression molded E-Glass/Nylon-6 composite samples with 3-4 weight% nanoclay and baseline polymer (polymer without nanoclay) confirmed significant improvements in compressive strength (˜122%) and shear strength (˜60%) in the nanoclay modified nanocomposites, in comparison with baseline properties. Uniaxial tensile tests showed a small increase in tensile strength (˜3.4%) with 3 wt % nanoclay loading. While the synergistic reinforcing influence of nanoparticle reinforcement is obvious, a simple rule-of-mixtures approach fails to quantify the dramatic increase in mechanical properties. Consequently, there is an immediate need to investigate and understand the mechanisms at the nanoscale that are responsible for such unprecedented strength enhancements. In this work, an innovative and effective method to model nano-structured components in a thermoplastic polymer matrix is proposed. Effort will be directed towards finding fundamental answers to the reasons for significant changes in mechanical properties of nanoparticle-reinforced thermoplastic composites. This research ensues a multiscale modeling approach in which (a) a concurrent simulations scheme is developed to visualize atomistic behavior of polymer molecules as a function of continuum scale loading conditions and (b) a novel nanoscale damage mechanics model is proposed to capture the constitutive behavior of polymer nano composites (PNC). The proposed research will contribute towards the understanding of advanced nanostructured composite materials, which should subsequently benefit the composites manufacturing industry.

  12. Phenylene ring dynamics in phenoxy and the effect of intramolecular linkages on the dynamics of some engineering thermoplastics below the glass transition temperature

    SciTech Connect

    Arrese-Igor, Silvia; Arbe, Arantxa [Centro Fisica de Materiales (CSIC-UPV/EHU), Apartado 1072, 20080 San Sebastian (Spain); Alegria, Angel [Centro Fisica de Materiales (CSIC-UPV/EHU), Apartado 1072, 20080 San Sebastian (Spain); Departamento de Fisica de Materiales, UPV/EHU, Apartado 1072, 20080 San Sebastian (Spain); Colmenero, Juan [Centro Fisica de Materiales (CSIC-UPV/EHU), Apartado 1072, 20080 San Sebastian (Spain); Departamento de Fisica de Materiales, UPV/EHU, Apartado 1072, 20080 San Sebastian (Spain); Donostia International Physics Center, Apartado 1072, 20080 San Sebastian (Spain); Frick, Bernhard [Institut Laue-Langevin, Boite Postale 156, 38042 Grenoble Cedex 9 (France)

    2007-05-15

    We have investigated the dynamics of phenylene rings in the engineering thermoplastic bisphenol-A poly(hydroxyether)--phenoxy--below its glass transition temperature by means of neutron scattering techniques. A relatively wide dynamic range has been covered thanks to the combination of two different types of neutron spectrometers, time of flight and backscattering. Partially deuterated samples have been used in order to isolate the phenylene ring dynamics. The resulting neutron scattering signal of phenoxy has been described by a model that considers {pi} flips and oscillation motions for phenylene rings. The associated time scales are broadly distributed with mean activation energies equal to 0.41 and 0.21 eV, respectively. Finally, a comparative study with the literature shows that the dielectric and mechanical {gamma} relaxation in phenoxy exhibit good correlation with the characteristic times of the aliphatic chain published elsewhere and with the characteristic times observed for the motion of phenylene rings by neutron scattering. These findings are discussed in a more general framework that considers, in addition, previous results on other polymers, which also contain the bisphenol-A unit.

  13. Branched Polymers

    E-print Network

    Richard Kenyon; Peter Winkler

    2007-09-14

    Building on and from the work of Brydges and Imbrie, we give an elementary calculation of the volume of the space of branched polymers of order $n$ in the plane and in 3-space. Our development reveals some more general identities, and allows exact random sampling. In particular we show that a random 3-dimensional branched polymer of order $n$ has diameter of order $\\sqrt{n}$.

  14. Polymer Synthesis

    NSDL National Science Digital Library

    David Teegarden

    2004-01-01

    In the first four chapters, we have seen that many different kinds of polymers exist and that they have an extremely wide range of properties. Some are stiff, others are soluble, while still others are rubbery. There are plastics, and fibers, and adhesives, and foams. The structure and composition of the macromolecule dictate the ultimate properties. Structure and composition are determined when the macromolecule is synthesized. In this chapter we want to understand how monomers react together to form long polymer chains.

  15. Nuclear Instruments and Methods in Physics Research. Section B; Microstructural Characterization of Semi-Interpenetrating Polymer Networks by Positron Lifetime Spectroscopy

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Pater, Ruth H.; Eftekhari, Abe

    1998-01-01

    Thermoset and thermoplastic polyimides have complementary physical/mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. It is expected that a combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPNs) of thermoset LaRC(Trademark)-RP46 and thermoplastic LARC(Trademark)-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0: 100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical/mechanical properties. As expected, positronium atoms are not formed in these samples. The second life time component has been used to infer the positron trap dimensions. The "free volume" goes through a minimum at about 50:50 ratio, suggesting that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples have been discussed in this paper.

  16. Fabrication of 200-nm Dot Pattern on 15-m-Long Polymer Sheet Using Sheet Nanoimprint Method

    NASA Astrophysics Data System (ADS)

    Ogino, Masahiko; Hasegawa, Mitsuru; Sakaue, Keiji; Nagai, Shuuichi; Miyauchi, Akihiro

    2013-03-01

    Nanoimprint technology is one of the more promising methods for nano-fabrication. The thermal nanoimprint method can fabricate various kinds of thermoplastic materials and its process consists of heating, pressing, cooling, and separation and a lot of research was reported. We proposed and developed a sheet nanoimprint system that enables for continuous treatment of these four basic steps by introducing a belt-shaped nano-mold. We tried to fabricate dot patterns on polymer films by using a sheet nanoimprint method in this work. A 200 nm in diameter and 240 nm tall dots (aspect ratio 1.4) were formed directly onto a 15-m-long polystyrene film. It is important in the field of industrial applications to fabricate nano-scale patterns over a large area with a high throughput. We demonstrated that the sheet nanoimprint is an attractive method for the direct patterning of nano-scale patterns on thermo-plastic films.

  17. Effect of Polymer Form and its Consolidation on Mechanical Properties and Quality of Glass/PBT Composites

    NASA Astrophysics Data System (ADS)

    Durai Prabhakaran, R. T.; Pillai, Saju; Charca, Samuel; Oshkovr, Simin Ataollahi; Knudsen, Hans; Andersen, Tom Løgstrup; Bech, Jakob Ilsted; Thomsen, Ole Thybo; Lilholt, Hans

    2014-04-01

    The aim of this study was to understand the role of the processing in determining the mechanical properties of glass fibre reinforced polybutylene terephthalate composites (Glass/PBT). Unidirectional (UD) composite laminates were manufactured by the vacuum consolidation technique using three different material systems included in this study; Glass/CBT (CBT160 powder based resin), Glass/PBT (prepreg tapes), and Glass/PBT (commingled yarns). The different types of thermoplastic polymer resin systems used for the manufacturing of the composite UD laminate dictate the differences in final mechanical properties which were evaluated by through compression, flexural and short beam transverse bending tests. Microscopy was used to evaluate the quality of the processed laminates, and fractography was used to characterize the observed failure modes. The study provides an improved understanding of the relationships between processing methods, resin characteristics, and mechanical performance of thermoplastic resin composite materials.

  18. CO2-laser-assisted processing of glass fiber-reinforced thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Brecher, Christian; Emonts, Michael; Schares, Richard Ludwig; Stimpfl, Joffrey

    2013-02-01

    To fully exploit the potential of fiber-reinforced thermoplastic composites (FRTC) and to achieve a broad industrial application, automated manufacturing systems are crucial. Investigations at Fraunhofer IPT have proven that the use of laser system technology in processing FRTC allows to achieve high throughput, quality, flexibility, reproducibility and out-of-autoclave processing simultaneously. As 90% of the FRP in Europe1 are glass fiber-reinforced a high impact can be achieved by introducing laser-assisted processing with all its benefits to glass fiber-reinforced thermoplastics (GFRTC). Fraunhofer IPT has developed the diode laser-assisted tape placement (laying and winding) to process carbon fiber-reinforced thermoplastic composites (CFRTC) for years. However, this technology cannot be transferred unchanged to process milky transparent GFRTC prepregs (preimpregnated fibers). Due to the short wavelength (approx. 980 nm) and therefore high transmission less than 20% of the diode laser energy is absorbed as heat into non-colored GFRTC prepregs. Hence, the use of a different wave length, e.g. CO2-laser (10.6 ?m) with more than 90% laser absorption, is required to allow the full potential of laser-assisted processing of GFRTC. Also the absorption of CO2-laser radiation at the surface compared to volume absorption of diode laser radiation is beneficial for the interlaminar joining of GFRTC. Fraunhofer IPT is currently developing and investigating the CO2-laser-assisted tape placement including new system, beam guiding, process and monitoring technology to enable a resource and energy efficient mass production of GFRP composites, e.g. pipes, tanks, masts. The successful processing of non-colored glass fiber-reinforced Polypropylene (PP) and Polyphenylene Sulfide (PPS) has already been proven.

  19. Production and characterization of thermoplastic cassava starch, functionalized poly(lactic acid), and their reactive compatibilized blends

    NASA Astrophysics Data System (ADS)

    Detyothin, Sukeewan

    Cassava starch was blended with glycerol using a co-rotating twin-screw extruder (TSE). Thermoplastic cassava starch (TPCS) at a ratio of 70/30 by weight of cassava/glycerol was selected and further blended with other polymers. TPCS sheets made from compression molding had low tensile strength (0.45 +/- 0.05 MPa) and Young's modulus (1.24 +/- 0.58 MPa), but moderate elongation at break (83.0 +/- 0.18.6%), medium level of oxygen permeability, and high water vapor permeability with a very high rate of water absorption. TPCS was blended with poly(lactic acid) (PLA) at various ratios by using a TSE. The blend resins exhibited good properties such as increased thermal stability (Tmax) and crystallinity of PLA, and improved water sensitivity and processability of TPCS. PLA and TPCS exhibited a high interfacial tension between the two phases of 7.9 mJ·m -2, indicating the formation of an incompatible, immiscible blend. SEM micrographs showed a non-homogeneous distribution of TPCS droplets in the PLA continuous phase. TEM micrographs of the blend films made by cast-film extrusion showed coalescence of the TPCS droplets in the PLA continuous phase of the blend, indicating that the compatibility between the polymer pair needs to be improved. A response surface methodology (RSM) design was used to analyze the effects of maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox or L101) contents, and TSE screw speed on the degree of grafted MA and number average molecular weight (Mn) of functionalized PLA (PLA-g-MA), a reactive compatibilizer. PLA-g- MA made by reactive extrusion had an array of colors depending on the content of L101 and MA used. New FTIR peaks suggested that MA was grafted onto the PLA backbone and oligomeric MA may occur. Increasing L101 increased the degree of grafting and decreased Mn, but the Mn of the PLA-g-MA's produced with a high amount of L101 was stable during storage. MA exhibited an optimum concentration for maximizing the degree of grafted MA, and increasing MA content retarded the reduction of Mn during processing. However, the Mn of PLA-g-MA during storage decreased more rapidly with a high content of MA. TSE screw speed had an impact on the Mn with the maximum value predicted at 20 rpm. PLA-g-MA compounds differing in Mn and/or grafted MA content were used as reactive polymers with TPCS (to produce binary blends) and as reactive compatibilizers (to produce ternary blends of PLA/TPCS/PLA-g-MA) with TPCS content of 30 wt% using a TSE. As a result of maleation, PLA-g-MA had a higher grafted MA content with a lower Mn, and higher PI. The interaction of anhydride groups from PLA-g-MA and hydroxyl groups from TPCS was found by FTIR. The reactive binary blends exhibited a change in thermal stability, decrease of Tcc, the presence of double melting peaks, and an increase of the Tgs of glycerol and starch. The higher the grafted MA content and/or the higher Mn of the PLA- g-MA used, the better were the distribution and smaller the TPCS domains obtained in the blends. The highest elongation at break was achieved when 30 wt% TPCS was blended with 70 wt% of PLA having 0.1 wt% of grafted MA and Mn of PLA-g-MA with a 45 kDa. Finally, the optimum PLA-g-MA was determined by using the results from PLA-g-MA RSM design and the reactive blending.

  20. Novel layer-by-layer procedure for making nylon-6 nanofiber reinforced high strength, tough, and transparent thermoplastic polyurethane composites.

    PubMed

    Jiang, Shaohua; Duan, Gaigai; Hou, Haoqing; Greiner, Andreas; Agarwal, Seema

    2012-08-01

    We highlight a novel composite fabrication method based on solution casting, electrospinning, and film stacking for preparing highly transparent nylon-6 nanofiber reinforced thermoplastic polyurethane (TPU) composite films. The procedure is simple and can be extended to the other thermoplastics. The morphology of fiber/matrix interface and the properties of composite films were also investigated. The method led to a significant reinforcement in mechanical properties of TPU like tensile strength, E modulus, strain, and toughness just using very small amounts of nylon fibers (about 0.4-1.7 wt %; 150-300 nm diameter). The enhanced mechanical properties were achieved without sacrificing optical properties like transparency of TPU. PMID:22817392

  1. TECHNIQUES AND RESULTS FOR FIBER LENGTH DISTRIBUTION DETERMINATION AS A FUNCTION OF THICKNESS IN LONG FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil [ORNL; Frame, Barbara J [ORNL; Pryor, Jeff M [ORNL; Nguyen, Ba N. [Pacific Northwest National Laboratory (PNNL); TuckerIII, Charles L. [University of Illinois, Urbana-Champaign; Case, Scott [Virginia Polytechnic Institute and State University; Penumadu, Dayakar [University of Tennessee, Knoxville (UTK); Guffey, Eric W [University of Tennessee, Knoxville (UTK)

    2008-01-01

    A novel measurement technique was developed to obtain unbiased fiber length distribution (FLD) measurements at specified locations in the thickness of the sample. This technique relies on elastic energy stored in long fiber thermoplastics (LFT), which is released during partially constrained burn-off. This release results in an increase of thickness dimension of the sample and partial disentanglement, allowing sample selection and subsequent filament separation. Quantitative FLD results and the measurement technique are discussed in detail. The FLD in long fiber reinforced injection molded thermoplastics is shown to vary as a function of thickness.

  2. Biobased building blocks for the rational design of renewable block polymers.

    PubMed

    Holmberg, Angela L; Reno, Kaleigh H; Wool, Richard P; Epps, Thomas H

    2014-10-14

    Block polymers (BPs) derived from biomass (biobased) are necessary components of a sustainable future that relies minimally on petroleum-based plastics for applications ranging from thermoplastic elastomers and pressure-sensitive adhesives to blend compatibilizers. To facilitate their adoption, renewable BPs must be affordable, durable, processable, versatile, and reasonably benign. Their desirability further depends on the relative sustainability of the renewable resources and the methods employed in the monomer and polymer syntheses. Various strategies allow these BPs' characteristics to be tuned and enhanced for commercial applications, and many of these techniques also can be applied to manipulate the wide-ranging mechanical and thermal properties of biobased and self-assembling block polymers. From feedstock to application, this review article highlights promising renewable BPs, plus their material and assembly properties, in support of de novo design strategies that could revolutionize material sustainability. PMID:25131385

  3. Orthotropic elasto-plastic behavior of AS4/APC-2 thermoplastic composite in compression

    NASA Technical Reports Server (NTRS)

    Sun, C. T.; Rui, Y.

    1989-01-01

    Uniaxial compression tests were performed on off-axis coupon specimens of unidirectional AS4/APC-2 thermoplastic composite at various temperatures. The elasto-plastic and strength properties of AS4/APC-2 composite were characterized with respect to temperature variation by using a one-parameter orthotropic plasticity model and a one-parameter failure criterion. Experimental results show that the orthotropic plastic behavior can be characterized quite well using the plasticity model, and the matrix-dominant compressive strengths can be predicted very accurately by the one-parameter failure criterion.

  4. Characterization of elastic-plastic properties of AS4/APC-2 thermoplastic composite

    NASA Technical Reports Server (NTRS)

    Sun, C. T.; Yoon, K. J.

    1988-01-01

    Elastic and inelastic properties of AS4/APC-2 composites were characterized with respect to temperature variation by using a one-parameter orthotropic plasticity model and a one parameter failure criterion. Simple uniaxial off-axis tension tests were performed on coupon specimens of unidirectional AS4/APC-2 thermoplastic composite at various temperatures. To avoid the complication caused by the extension-shear coupling effect in off-axis testing, new tabs were designed and used on the test specimens. The experimental results showed that the nonlinear behavior of constitutive relations and the failure strengths can be characterized quite well using the one parameter plasticity model and the failure criterion, respectively.

  5. X-ray diffraction studies of model compounds of thermoplastic polyimides

    NASA Technical Reports Server (NTRS)

    Wakelyn, N. T.; Pratt, J. R.

    1989-01-01

    Several model compounds which represent aspects of the chemical structure of the Langley Research Center thermoplastic (LARC-TPI) have been synthesized for comparison studies using wide angle X-ray scattering (WAXS) as the discriminatory tool. The model compounds included N-phenylphthalimide, 3,3',4,4'-benzophenonetetracarboxylic diphthalimide, and N,N'-diphenyl-3,3',4,4'-benzophenonetetracarboxylic diphthalimide. X-ray diffraction studies of appropriate model compounds can yield information to aid in the understanding of polymeric crystallographic structure. Crystallinity and physical property changes can thus be induced into materials having complicated structures by chemical and thermal processes.

  6. Temperature rise due to mechanical energy dissipation in undirectional thermoplastic composites(AS4/PEEK)

    NASA Technical Reports Server (NTRS)

    Georgious, I. T.; Sun, C. T.

    1992-01-01

    The history of temperature rise due to internal dissipation of mechanical energy in insulated off-axis uniaxial specimens of the unidirectional thermoplastic composite (AS4/PEEK) has been measured. The experiment reveals that the rate of temperature rise is a polynomial function of stress amplitude: It consists of a quadratic term and a sixth power term. This fact implies that the specific heat of the composite depends on the stretching its microstructure undergoes during deformation. The Einstein theory for specific heat is used to explain the dependence of the specific heat on the stretching of the microstructure.

  7. Monitoring processing properties of high performance thermoplastics using frequency dependent electromagnetic sensing

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.; Delos, S. E.; Hoff, M. S.; Weller, L. W.; Haverty, P. D.

    1987-01-01

    An in situ NDE dielectric impedance measurement method has been developed for ascertaining the cure processing properties of high temperature advanced thermoplastic and thermosetting resins, using continuous frequency-dependent measurements and analyses of complex permittivity over 9 orders of magnitude and 6 decades of frequency at temperatures up to 400 C. Both ionic and Debye-like dipolar relaxation processes are monitored. Attention is given to LARC-TPI, PEEK, and poly(arylene ether) resins' viscosity, glass transition temperature, recrystallization, and residual solvent content and evolution properties.

  8. Dissipation of mechanical work and temperature rise in AS4/PEEK thermoplastic composite

    NASA Technical Reports Server (NTRS)

    Georgiou, I.; Sun, C. T.

    1990-01-01

    The dissipated mechanical work per cycle of sinusoidal stress in the thermoplastic composite material AS4/PEEK was measured as a function of stress amplitude for fixed frequency and fiber orientation. The experimental result shows that the dissipated work per cycle is proportional to the square of the stress amplitude. Using the concept of the equivalent isotropic material, it is shown that the relaxation modulus satisfies a proportionality condition. Also, the rate of temperature rise due to sinusoidal stresses has been measured as a function of stress amplitude. The result shows that the rate of temperature rise is not proportional to the square of the stress amplitude.

  9. Solid particle erosion of polymers and composites

    NASA Astrophysics Data System (ADS)

    Friedrich, K.; Almajid, A. A.

    2014-05-01

    After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

  10. The effect of free radical inhibitor on the sensitized radiation crosslinking and thermal processing stabilization of polyurethane shape memory polymers.

    PubMed

    Hearon, Keith; Smith, Sarah E; Maher, Cameron A; Wilson, Thomas S; Maitland, Duncan J

    2013-02-01

    The effects of free radical inhibitor on the electron beam crosslinking and thermal processing stabilization of novel radiation crosslinkable polyurethane shape memory polymers (SMPs) blended with acrylic radiation sensitizers have been determined. The SMPs in this study possess novel processing capabilities-that is, the ability to be melt processed into complex geometries as thermoplastics and crosslinked in a secondary step using electron beam irradiation. To increase susceptibility to radiation crosslinking, the radiation sensitizer pentaerythritol triacrylate (PETA) was solution blended with thermoplastic polyurethane SMPs made from 2-butene-1,4-diol and trimethylhexamethylene diisocyanate (TMHDI). Because thermoplastic melt processing methods such as injection molding are often carried out at elevated temperatures, sensitizer thermal instability is a major processing concern. Free radical inhibitor can be added to provide thermal stabilization; however, inhibitor can also undesirably inhibit radiation crosslinking. In this study, we quantified both the thermal stabilization and radiation crosslinking inhibition effects of the inhibitor 1,4-benzoquinone (BQ) on polyurethane SMPs blended with PETA. Sol/gel analysis of irradiated samples showed that the inhibitor had little to no inverse effects on gel fraction at concentrations of 0-10,000 ppm, and dynamic mechanical analysis showed only a slight negative correlation between BQ composition and rubbery modulus. The 1,4-benzoquinone was also highly effective in thermally stabilizing the acrylic sensitizers. The polymer blends could be heated to 150°C for up to five hours or to 125°C for up to 24 hours if stabilized with 10,000 ppm BQ and could also be heated to 125°C for up to 5 hours if stabilized with 1000 ppm BQ without sensitizer reaction occurring. We believe this study provides significant insight into methods for manipulation of the competing mechanisms of radiation crosslinking and thermal stabilization of radiation sensitizers, thereby facilitating further development of radiation crosslinkable thermoplastic SMPs. PMID:23226930

  11. The effect of free radical inhibitor on the sensitized radiation crosslinking and thermal processing stabilization of polyurethane shape memory polymers

    PubMed Central

    Hearon, Keith; Smith, Sarah E.; Maher, Cameron A.; Wilson, Thomas S.; Maitland, Duncan J.

    2012-01-01

    The effects of free radical inhibitor on the electron beam crosslinking and thermal processing stabilization of novel radiation crosslinkable polyurethane shape memory polymers (SMPs) blended with acrylic radiation sensitizers have been determined. The SMPs in this study possess novel processing capabilities—that is, the ability to be melt processed into complex geometries as thermoplastics and crosslinked in a secondary step using electron beam irradiation. To increase susceptibility to radiation crosslinking, the radiation sensitizer pentaerythritol triacrylate (PETA) was solution blended with thermoplastic polyurethane SMPs made from 2-butene-1,4-diol and trimethylhexamethylene diisocyanate (TMHDI). Because thermoplastic melt processing methods such as injection molding are often carried out at elevated temperatures, sensitizer thermal instability is a major processing concern. Free radical inhibitor can be added to provide thermal stabilization; however, inhibitor can also undesirably inhibit radiation crosslinking. In this study, we quantified both the thermal stabilization and radiation crosslinking inhibition effects of the inhibitor 1,4-benzoquinone (BQ) on polyurethane SMPs blended with PETA. Sol/gel analysis of irradiated samples showed that the inhibitor had little to no inverse effects on gel fraction at concentrations of 0-10,000 ppm, and dynamic mechanical analysis showed only a slight negative correlation between BQ composition and rubbery modulus. The 1,4-benzoquinone was also highly effective in thermally stabilizing the acrylic sensitizers. The polymer blends could be heated to 150°C for up to five hours or to 125°C for up to 24 hours if stabilized with 10,000 ppm BQ and could also be heated to 125°C for up to 5 hours if stabilized with 1000 ppm BQ without sensitizer reaction occurring. We believe this study provides significant insight into methods for manipulation of the competing mechanisms of radiation crosslinking and thermal stabilization of radiation sensitizers, thereby facilitating further development of radiation crosslinkable thermoplastic SMPs. PMID:23226930

  12. Self-healing multiphase polymers via dynamic metal-ligand interactions.

    PubMed

    Mozhdehi, Davoud; Ayala, Sergio; Cromwell, Olivia R; Guan, Zhibin

    2014-11-19

    A new self-healing multiphase polymer is developed in which a pervasive network of dynamic metal-ligand (zinc-imidazole) interactions are programmed in the soft matrix of a hard/soft two-phase brush copolymer system. The mechanical and dynamic properties of the materials can be tuned by varying a number of molecular parameters (e.g., backbone/brush degree of polymerization and brush density) as well as the ligand/metal ratio. Following mechanical damage, these thermoplastic elastomers show excellent self-healing ability under ambient conditions without any intervention. PMID:25348857

  13. Polymer inflation

    E-print Network

    Syed Moeez Hassan; Viqar Husain; Sanjeev S. Seahra

    2015-03-05

    We consider the semi-classical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a gaussian coherent state. For quadratic potentials, the semi-classical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by a epoch of slow-roll inflation. We compute polymer corrections to the slow roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. We also show how in this model, it is possible to obtain a significant amount of slow-roll inflation from sub-Planckain initial data, hence circumventing some of the criticisms of standard scenarios. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.

  14. Polymer inflation

    E-print Network

    Hassan, Syed Moeez; Seahra, Sanjeev S

    2014-01-01

    We consider the semi-classical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a gaussian coherent state. For quadratic potentials, the semi-classical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by a epoch of slow-roll inflation. We compute polymer corrections to the slow roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.

  15. Polymer inflation

    NASA Astrophysics Data System (ADS)

    Hassan, Syed Moeez; Husain, Viqar; Seahra, Sanjeev S.

    2015-03-01

    We consider the semiclassical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a Gaussian coherent state. For quadratic potentials, the semiclassical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by an epoch of slow-roll inflation. We compute polymer corrections to the slow-roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. We also show how in this model, it is possible to obtain a significant amount of slow-roll inflation from sub-Planckian initial data, hence circumventing some of the criticisms of standard scenarios. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.

  16. Antimocrobial Polymer

    DOEpatents

    McDonald, William F. (Utica, OH); Huang, Zhi-Heng (Walnut Creek, CA); Wright, Stacy C. (Columbus, GA)

    2005-09-06

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

  17. Positron Lifetime Measurements in Semi-Interpenetrating Polymer Networks

    NASA Astrophysics Data System (ADS)

    Singh, Jag J.; Pater, Ruth H.; Sprinkle, Danny R.

    1998-03-01

    Physical interlocking is generally believed to be the dominant force that controls the morphology of a Semi-Interpenetrating Polymer Network (S-IPN). However, in our recent study (J. J. Singh, R. H. Pater, and A. Eftekhari: Nuclear Instruments and Methods - NIMB (To be published)) of S-IPN's prepared from thermosetting LaRC-RP46 and thermoplastic LaRC-IA polyimides, it was discovered that a strong electrostatic interaction between the constituent molecules enhances phase mixing. In order to further test this hypothesis, we replaced thermoplastic LaRC-IA by LaRC-SI. LaRC-SI has a rigid backbone which should prevent it from coming close to LaRCT-RP46 molecular chain, thereby minimizing electrostatic influences. Positron lifetime measurements were made in the new class of S-IPN samples. Experimental values of the free volume and the dielectric constant indicate that they are merely solid solutions of their constituents, without any measurable electrostatic effects. However, the density values of these materials suggest a slight repulsion (or enhanced separation) between the constituent chains.

  18. Polymer-based lab-on-a-chip lasers

    NASA Astrophysics Data System (ADS)

    Kristensen, A.; Balslev, S.; Bilenberg, B.; Gersborg-Hansen, M.; Nilsson, D.

    2004-12-01

    The integration of optical transducers is generally considered a key issue in the further development of lab-on-a-chip Microsystems. We present a technology for miniaturized, polymer based lasers, suitable for integration with planar waveguides and microfluidic networks. The lasers rely on the commercial laser dye Rhodamine 6G as active medium, and the laser resonator is defined in a thin film of polymer on a low refractive index substrate. Two types of devices are demonstrated: solid and microfluidic polymer based dye lasers. In the microfluidic dye lasers, the laser dye is dissolved in a suitable solvent and flushed though a microfluidic channel, which has the laser resonator embedded. For solid state dye lasers, the laser dye is dissolved in the polymer forming the laser resonator. The miniaturized dye lasers are optically pumped by a frequency doubled, pulsed Nd:YAG laser (at 532 nm), and emit at wavelengths between 560 nm and 590 nm. The lasers emit in the plane of the chip, and the emitted light is coupled into planar polymer waveguides on the chip. The feasibility of three types of polymers is demonstrated: SU-8, PMMA and a cyclo-olefin co-polymer (COC) - Topas. SU-8 is a negative tone photoresist, allowing patterning with conventional UV lithography. PMMA and Topas are thermoplasts, which are patterned by nanoimprint lithography (NIL). The lasing wavelength of the microfluidic dye lasers can be coarse tuned over 30 nm by varying the concentration of laser dye, and fine tuned by varying the refractive index of the solvent. This is utilized to realize a tunable laser, by on-chip mixing of dye, and two solvents of different index of refraction. The lasers were also integrated with waveguides and microfluidic networks.

  19. Glue Polymer

    NSDL National Science Digital Library

    Mid-continent Research for Education and Learning (McREL)

    2004-01-01

    What is a polymer, and what are some of its properties? This material is part of a series of hands-on science activities designed to arouse student interest. In this discovery activity students use white glue, water, and borax to make a vinyl polymer and study its properties. The activity includes a description, a list of science process skills and complex reasoning strategies being used, and a compilation of applicable K-12 national science education standards. Also provided are content topics, a list of necessary supplies, instructions, and presentation techniques. The content of the activity is explained, and assessment suggestions are provided.

  20. Nanocellulose in Polymer Composites and Biomedical: Research and Applications

    SciTech Connect

    Lu, Yuan [ORNL; Tekinalp, Halil L [ORNL; Peter, William H [ORNL; Eberle, Cliff [ORNL; Naskar, Amit K [ORNL; Ozcan, Soydan [ORNL

    2014-01-01

    Nanocellulose materials are nano-sized cellulose fibers or crystals that are produced by bacteria or derived from plants. These materials exhibit exceptional strength characteristics, light weight, transparency, and excellent biocompatibility. Compared to some other nanomaterials, nanocellulose is renewable and less expensive to produce. As such, a wide range of applications for nanocellulose has been envisioned. Most extensively studied areas include polymer composites and biomedical applications. Cellulose nanofibrils and nanocrystals have been used to reinforce both thermoplastic and thermoset polymers. Given the hydrophilic nature of these materials, the interfacial properties with most polymers are often poor. Various surface modification procedures have thus been adopted to improve the interaction between polymer matrix and cellulose nanofibrils or nanocrystals. In addition, the applications of nanocellulose as biomaterials have been explored including wound dressing, tissue repair, and medical implants. Nanocellulose materials for wound healing and periodontal tissue recovery have become commercially available, demonstrating the great potential of nanocellulose as a new generation of biomaterials. In this review, we highlight the applications of nanocellulose as reinforcing fillers for composites and the effect of surface modification on the mechanical properties as well as the application as biomaterials.

  1. An Elastic-Plastic and Strength Prediction Model for Injection-Molded Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Phelps, Jay; Tucker III, Charles L.; Bapanapalli, Satish K.

    2008-09-01

    This paper applies a recently developed model to predict the elastic-plastic stress/strain response and strength of injection-molded long-fiber thermoplastics (LFTs). The model combines a micro-macro constitutive modeling approach with experimental characterization and modeling of the composite microstructure to determine the composite stress/strain response and strength. Specifically, it accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length, orientation and volume fraction distributions in the composite formed by the injection-molding process. Injection-molded-long-glass-fiber/polypropylene (PP) specimens were prepared for mechanical characterization and testing. Fiber length, orientation, and volume fraction distributions were then measured at some selected locations for use in the computation. Fiber orientations in these specimens were also predicted using an anisotropic rotary diffusion model developed for LFTs. The stress-strain response of the as-formed composite was computed by an incremental procedure that uses the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption and a fiber orientation averaging technique. The model has been validated against the experimental stress-strain results obtained for these long-glass-fiber/PP specimens.

  2. Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge

    PubMed Central

    Kaltenboeck, Georg; Harris, Thomas; Sun, Kerry; Tran, Thomas; Chang, Gregory; Schramm, Joseph P.; Demetriou, Marios D.; Johnson, William L.

    2014-01-01

    The ability of the rapid-capacitive discharge approach to access optimal viscosity ranges in metallic glasses for thermoplastic processing is explored. Using high-speed thermal imaging, the heating uniformity and stability against crystallization of Zr35Ti30Cu7.5Be27.5 metallic glass heated deeply into the supercooled region is investigated. The method enables homogeneous volumetric heating of bulk samples throughout the entire supercooled liquid region at high rates (~105?K/s) sufficient to bypass crystallization throughout. The crystallization onsets at temperatures in the vicinity of the “crystallization nose” were identified and a Time-Temperature-Transformation diagram is constructed, revealing a “critical heating rate” for the metallic glass of ~1000?K/s. Thermoplastic process windows in the optimal viscosity range of 100–104?Pa·s are identified, being confined between the glass relaxation and the eutectic crystallization transition. Within this process window, near-net forging of a fine precision metallic glass part is demonstrated. PMID:25269892

  3. An Elastic-Plastic Damage Model for Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil

    2009-08-11

    This article proposes an elastic-plastic damage model that combines micromechanical modeling with continuum damage mechanics to predict the stress-strain response of injection-molded long-fiber thermoplastics. The model accounts for distributions of orientation and length of elastic fibers embedded in a thermoplastic matrix whose behavior is elastic-plastic and damageable. The elastic-plastic damage behavior of the matrix is described by the modified Ramberg-Osgood relation and the three-dimensional damage model in deformation assuming isotropic hardening. Fiber/matrix debonding is accounted for using a parameter that governs the fiber/matrix interface compliance. A linear relationship between this parameter and the matrix damage variable is assumed. First, the elastic-plastic damage behavior of the reference aligned-fiber composite containing the same fiber volume fraction and length distribution as the actual composite is computed using an incremental Eshelby-Mori-Tanaka mean field approach. The incremental response of the latter is then obtained from the solution for the aligned-fiber composite by averaging over all fiber orientations. The model is validated against the experimental stress-strain results obtained for long-glass-fiber/polypropylene specimens.

  4. Field Evaluation of the Potential for Creep in Thermoplastic Encapsulant Materials: Preprint

    SciTech Connect

    Kempe, M. D.; Miller, D. C.; Wohlgemuth, J.; Kurtz, S. R.; Moseley, J. M.; Shah, Q.; Tamizhmani, G.; Sakurai, K.; Inoue, M.; Doi, T.; Masuda, A.; Samuels, S. L.; Vanderpan, C. E.

    2012-06-01

    There has been recent interest in the use of thermoplastic encapsulant materials in photovoltaic modules to replace chemically crosslinked materials, e.g., ethylene-vinyl acetate. The related motivations include the desire to: reduce lamination time or temperature; use less moisture-permeable materials; use materials with better corrosion characteristics or with improved electrical resistance. However, the use of any thermoplastic material in a high-temperature environment raises safety and performance concerns, as the standardized tests currently do not expose the modules to temperatures in excess of 85 degrees C, though fielded modules may experience temperatures above 100 degrees C. Here 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 designed to chemically crosslink. One module set was exposed outdoors with insulation on the back side in Arizona in the summer, and an identical set was exposed in environmental chambers. High precision creep measurements (+/- 20 um) and performance measurements indicate that despite many of these polymeric materials being in the melt state during outdoor deployment, very little creep was seen because of their high viscosity, temperature heterogeneity across the modules, and the formation of chemical crosslinks in many of the encapsulants as they aged. In the case of the crystalline silicon modules, the physical restraint of the backsheet reduced the creep further.

  5. Method and apparatus for producing composites of materials exhibiting thermoplastic properties

    DOEpatents

    Garvey, Raymond E. (Knoxville, TN); Grostick, Edmund T. (Faragut, TN)

    1992-01-01

    A mobile device for the complete consolidation of layers of material which exhibit thermoplastic properties for the formation of a composite of the layers upon a complex contoured substrate. The principal of the device is to provide heating into the molten temperature range of the thermoplastic material, applying sufficient pressure to the layers to cause flow of the plastic for a time sufficient to achieve full consolidation of the layers, and quickly cooling the structure to prevent delamination or other non-consolidation action. In the preferred form, there is an element to deposit a layer of the mateiral against another layer in close proximity. The two layers are pre-heated to near the melting temperature, and then further heated into the melting temperature range as they are brought into intimate contact with sufficient pressure to cause flow of the plastic for a time sufficient to achieve the full consolidation. The structure is then cooled. The mechanism for the application of pressure is selected such that the layers can be deformed to conform to a complex contour. In the preferred form, this pressurization is produced using a compliant hood that supplies both the pressure and at least a portion of the melting temperature, as well as the cooling. The apparatus, and method of operation, are described relative to the use of fiber-reinforced PEEK in the making of fully-consolidated composites. Other applications are discussed.

  6. A Complex Shaped Reinforced Thermoplastic Composite Part Made of Commingled Yarns With Integrated Sensor

    NASA Astrophysics Data System (ADS)

    Risicato, Jean-Vincent; Kelly, Fern; Soulat, Damien; Legrand, Xavier; Trümper, Wolfgang; Cochrane, Cedric; Koncar, Vladan

    2015-02-01

    This paper focuses on the design and one shot manufacturing process of complex shaped composite parts based on the overbraiding of commingled yarns. The commingled yarns contain thermoplastic fibres used as the matrix and glass fibres as the reinforcement material. This technology reduces the flow path length for the melted thermoplastic and aims to improve the impregnation of materials with high viscosity. The tensile strength behaviour of the material was firstly investigated in order to evaluate the influence of the manufacturing parameters on flat structured braids that have been consolidated on a heating press. A good compatibility between the required geometry and the braiding process was observed. Additionally, piezo-resistive sensor yarns, based on glass yarns coated with PEDOT: PSS, have been successfully integrated within the composite structure. The sensor yarns have been inserted into the braided fabric, before consolidation. The inserted sensors provide the ability to monitor the structural health of the composite part in a real time. The design and manufacture of the complete complex shaped part has then been successfully achieved.

  7. Fabrication of thermoplastic ductile films of chitin butyrate/poly(?-caprolactone) blends and their cytocompatibility.

    PubMed

    Hashiwaki, Hiroki; Teramoto, Yoshikuni; Nishio, Yoshiyuki

    2014-12-19

    We fabricate thermoplastic films of chitin burtyrate (ChB)/poly(?-caprolactone) (PCL) blends with different degree of miscibility (miscible (M), partially miscible (PM), and immiscible (IM)), and examined the feasibility as a cell scaffold system through evaluating mechanical properties and cytocompatibility. We found a remediation of the brittleness and an increase in ductility of ChB by blending PCL for the M and PM blends. The blend films were subjected to alkaline hydrolysis (2-M NaOH/37°C/48 h) with expectation of the improvement of the surface hydrophilicity and cell accessibility. ATR-FTIR spectroscopy of the alkaline-treated PM and IM films revealed that PCL component and ester side-chains of acyl chitin were selectively removed from the surface domain. L929 fibroblast cells well adhered and proliferated on these films. Therefore, the materials possess a great potential for the utilization as a thermoplastic cell scaffold in tissue engineering by adequate selection of the degree of miscibility and post treatment. PMID:25263898

  8. Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge.

    PubMed

    Kaltenboeck, Georg; Harris, Thomas; Sun, Kerry; Tran, Thomas; Chang, Gregory; Schramm, Joseph P; Demetriou, Marios D; Johnson, William L

    2014-01-01

    The ability of the rapid-capacitive discharge approach to access optimal viscosity ranges in metallic glasses for thermoplastic processing is explored. Using high-speed thermal imaging, the heating uniformity and stability against crystallization of Zr35Ti30Cu7.5Be27.5 metallic glass heated deeply into the supercooled region is investigated. The method enables homogeneous volumetric heating of bulk samples throughout the entire supercooled liquid region at high rates (~10(5) K/s) sufficient to bypass crystallization throughout. The crystallization onsets at temperatures in the vicinity of the "crystallization nose" were identified and a Time-Temperature-Transformation diagram is constructed, revealing a "critical heating rate" for the metallic glass of ~1000 K/s. Thermoplastic process windows in the optimal viscosity range of 10(0)-10(4) Pa · s are identified, being confined between the glass relaxation and the eutectic crystallization transition. Within this process window, near-net forging of a fine precision metallic glass part is demonstrated. PMID:25269892

  9. Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge

    NASA Astrophysics Data System (ADS)

    Kaltenboeck, Georg; Harris, Thomas; Sun, Kerry; Tran, Thomas; Chang, Gregory; Schramm, Joseph P.; Demetriou, Marios D.; Johnson, William L.

    2014-10-01

    The ability of the rapid-capacitive discharge approach to access optimal viscosity ranges in metallic glasses for thermoplastic processing is explored. Using high-speed thermal imaging, the heating uniformity and stability against crystallization of Zr35Ti30Cu7.5Be27.5 metallic glass heated deeply into the supercooled region is investigated. The method enables homogeneous volumetric heating of bulk samples throughout the entire supercooled liquid region at high rates (~105 K/s) sufficient to bypass crystallization throughout. The crystallization onsets at temperatures in the vicinity of the ``crystallization nose'' were identified and a Time-Temperature-Transformation diagram is constructed, revealing a ``critical heating rate'' for the metallic glass of ~1000 K/s. Thermoplastic process windows in the optimal viscosity range of 100-104 Pa.s are identified, being confined between the glass relaxation and the eutectic crystallization transition. Within this process window, near-net forging of a fine precision metallic glass part is demonstrated.

  10. Glue-free assembly of glass fiber reinforced thermoplastics using laser light

    NASA Astrophysics Data System (ADS)

    Binetruy, C.; Clement, S.; Deleglise, M.; Franz, C.; Knapp, W.; Oumarou, M.; Renard, J.; Roesner, A.

    2011-05-01

    The use of laser light for bonding of continuous fiber reinforced thermoplastic composites (CFTPC) offers new possibilities to overcome the constraints of conventional joining technologies. Laser bonding is environmentally friendly as no chemical additive or glue is necessary. Accuracy and flexibility of the laser process as well as the quality of the weld seams provide benefits which are already used in many industrial applications. Laser transmission welding has already been introduced in manufacturing of short fiber thermoplastic composites. The laser replaces hot air in tapelaying systems for pre-preg carbon fiber placement. The paper provides an overview concerning the technical basics of the joining process and outline some material inherent characteristics to be considered when using continuous glass fiber reinforced composites The technical feasibility and the mechanical characterization of laser bonded CFTPC are demonstrated. The influence of the different layer configurations on the laser interaction with the material is investigated and the dependency on the mechanical strength of the weld seem is analyzed. The results show that the laser provides an alternative joining technique and offers new perspectives to assemble structural components emerging in automotive or aeronautical manufacturing. It overcomes the environmental and technical difficulties related to existing gluing processes.

  11. Analysis of pultrusion processing for long fiber reinforced thermoplastic composite system

    NASA Technical Reports Server (NTRS)

    Tso, W.; Hou, T. H.; Tiwari, S. N.

    1993-01-01

    Pultrusion is one of the composite processing technology, commonly recognized as a simple and cost-effective means for the manufacturing of fiber-reinforced, resin matrix composite parts with different regular geometries. Previously, because the majority of the pultruded composite parts were made of thermosetting resin matrix, emphasis of the analysis on the process has been on the conservation of energy from various sources, such as heat conduction and the curing kinetics of the resin system. Analysis on the flow aspect of the process was almost absent in the literature for thermosetting process. With the increasing uses of thermoplastic materials, it is desirable to obtain the detailed velocity and pressure profiles inside the pultrusion die. Using a modified Darcy's law for flow through porous media, closed form analytical solutions for the velocity and pressure distributions inside the pultrusion die are obtained for the first time. This enables us to estimate the magnitude of viscous dissipation and it's effects on the pultruded parts. Pulling forces refined in the pultrusion processing are also analyzed. The analytical model derived in this study can be used to advance our knowledge and control of the pultrusion process for fiber reinforced thermoplastic composite parts.

  12. Novel starch-based PVA thermoplastic capsules for hydrophilic lipid-based formulations.

    PubMed

    Misic, Zdravka; Muffler, Katharina; Sydow, Georg; Kuentz, Martin

    2012-12-01

    For decades, gelatin has been used in the rotary die process as a shell-forming material of soft capsules because of its unique physicochemical properties. However, with respect to the encapsulation of comparatively hydrophilic lipid-based formulations, gelatin has one considerable drawback: Immediately after production, the capsule shell contains a large amount of water (up to 35%). There is the potential for water to migrate from the capsule shell into the formulation, which will lead to a decrease in drug solubility and, in turn, the potential for drug crystallization. The present study introduces a novel capsule material that was obtained from extrusion. The starch-based polyvinyl alcohol thermoplastic capsules (S-PVA-C) mainly comprised a blend of starch and PVA. Gelatin and the novel material were used to encapsulate a hydrophilic lipid-based system of fenofibrate. Considerable water migration was observed from the soft gelatin shell to the hydrophilic formulation during drying and drug crystallization resulted in soft gelatin capsules. In contrast, S-PVA-C displayed no substantial water exchange or drug crystallization upon storage. The thermoplastic capsule material further exhibited more surface roughness and higher resistance to mechanical deformation compared with gelatin. In conclusion, S-PVA-C provided a robust drug product following encapsulation of a rather hydrophilic lipid-based formulation. PMID:22949383

  13. Aquaplast thermoplastic (Opti-Mold). A unique moldable tie-down dressing for full-thickness skin grafts.

    PubMed

    Fish, F S; Hilger, P A

    1994-04-01

    Aquaplast thermoplastic (Opti-Mold), a unique moldable "tie-down" dressing, can be heated, shaped, and sutured in place over full-thickness skin grafts. It allows for excellent uniform pressure over a skin graft while also allowing for drainage from the graft bed, and is particularly useful for the contoured surfaces of the nose and ears. PMID:8163744

  14. Long glass fiber orientation in thermoplastic composites using a model that accounts for the flexibility of the fibers

    E-print Network

    Wapperom, Peter

    Long glass fiber orientation in thermoplastic composites using a model that accounts Mechanical properties of long glass fiber composites, used in various industrial applications, are dependant are explored to predict the orientation of long glass fibers in the concentrated regime that take the flexible

  15. 2-D Simulations of Orientation in Highly Concentrated Short Glass Fiber Thermoplastic Composites Made by Injection Molding

    E-print Network

    Wapperom, Peter

    Made by Injection Molding Gregorio M. Vélez-Garcíaa , Kevin C. Ortmanb , Aaron P.R. Eberleb , Peter fiber composites is required in order to optimize the mold design of injection molding composites microscopy. Introduction Injection molded, short-glass fiber thermoplastic composites are an attractive

  16. Morphological and mechanical characterization of thermoplastic starch and its blends with polylactic acid using cassava starch and bagasse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aims the use of an agro waste coming from the industrialization of cassava starch, known as cassava bagasse (BG). This material contains residual starch and cellulose fibers which can be used to obtain thermoplastic starch (TPS) and /or blends reinforced with fibers. In this context, it w...

  17. Properties of shape memory polyurethane used as a low-temperature thermoplastic biomedical orthotic material: influence of hard segment content.

    PubMed

    Meng, Qinghao; Hu, Jinlian; Zhu, Yong

    2008-01-01

    A series of PCL-based shape memory polyurethanes was synthesized via bulk pre-polymerization. Their thermal, mechanical properties, shape memory properties, softening and hardening processes were investigated by the experimental approach and made comparison with a commercially available orthotic material. The cytotoxicity of the low-temperature thermoplastic polyurethane was tested. The results suggest that the soft segment phase of the shape memory polyurethanes has a melting transition at about 36-46 degrees C, which makes them possible low-temperature thermoplastic materials. The hard segment phase has a two-fold effect on the shape memory polyurethane as a low-temperature thermoplastic orthotic material: increasing tensile mechanical strength at room temperature, which enables it to be used in circumstances where high tensile strength is required; and reducing low-temperature malleability and fixity ratio, which make it difficult to fabricate orthotic devices. To obtain a shape memory polyurethane with excellent low-temperature thermoplastic properties for orthopaedical surgical use, the hard segment content should not be above 22 wt%. At last, a prototype wrist orthosis was easily fabricated at 60 degrees C with hand using a shape memory polyurethane with 16 wt% hard segment content. Cytotoxicity tests indicate that the wrist orthotic material is not cytotoxic. PMID:18973722

  18. Numerical Analysis of a High Power Piezoelectric Transducer Used in the Cutting and Welding of Thermoplastic Textiles

    Microsoft Academic Search

    João Batista da Silva; Nilson Noris Franceschetti; Julio Cezar Adamowski

    High power piezoelectric transducers have been used in the ultrasonic cutting and welding of thermoplastic textiles. The acoustical energy generated by a sandwich type power transducer is transferred to an wide blade-shaped horn through an acoustic amplifier. The transmission efficiency depends on the transducer and the horn assembly vibrational behavior. This paper presents a finite element analysis of a high

  19. TECHNIQUES AND RESULTS FOR FIBER LENGTH DISTRIBUTION DETERMINATION AS A FUNCTION OF THICKNESS IN LONG FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    Microsoft Academic Search

    Vlastimil Kunc; Barbara Frame; Jeff Pryor; Ba Nghiep Nguyen; Charles L. Tucker; Scott Case; Dayakar Penumadu; Eric W. Guffey

    A novel measurement technique was developed to obtain unbiased fiber length distribution (FLD) measurements at specified locations in the thickness of the sample. This technique relies on elastic energy stored in long fiber thermoplastics (LFT), which is released during partially constrained burn-off. This release results in an increase of thickness dimension of the sample and partial disentanglement, allowing sample selection

  20. Polymer solutions

    DOEpatents

    Krawczyk, Gerhard Erich (Bremen, DE); Miller, Kevin Michael (West Dundee, IL)

    2011-07-26

    There is provided a method of making a polymer solution comprising polymerizing one or more monomer in a solvent, wherein said monomer comprises one or more ethylenically unsaturated monomer that is a multi-functional Michael donor, and wherein said solvent comprises 40% or more by weight, based on the weight of said solvent, one or more multi-functional Michael donor.

  1. Polymer Blends

    Microsoft Academic Search

    D. R. Paul; J. W. Barlow

    1980-01-01

    The concept of appropriately combining two or more different polymers to obtain a new material system with the desirable features of its constituents is not new. Over the years, numerous systems based on the chemical combination of different monomers through random, block, and graft copolymerization methods have been developed with this goal in mind. For similar reasons, the coatings and

  2. Antimicrobial polymers.

    PubMed

    Jain, Anjali; Duvvuri, L Sailaja; Farah, Shady; Beyth, Nurit; Domb, Abraham J; Khan, Wahid

    2014-12-01

    Better health is basic requirement of human being, but the rapid growth of harmful pathogens and their serious health effects pose a significant challenge to modern science. Infections by pathogenic microorganisms are of great concern in many fields such as medical devices, drugs, hospital surfaces/furniture, dental restoration, surgery equipment, health care products, and hygienic applications (e.g., water purification systems, textiles, food packaging and storage, major or domestic appliances etc.) Antimicrobial polymers are the materials having the capability to kill/inhibit the growth of microbes on their surface or surrounding environment. Recently, they gained considerable interest for both academic research and industry and were found to be better than their small molecular counterparts in terms of enhanced efficacy, reduced toxicity, minimized environmental problems, resistance, and prolonged lifetime. Hence, efforts have focused on the development of antimicrobial polymers with all desired characters for optimum activity. In this Review, an overview of different antimicrobial polymers, their mechanism of action, factors affecting antimicrobial activity, and application in various fields are given. Recent advances and the current clinical status of these polymers are also discussed. PMID:25408272

  3. Polymers Pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore

    E-print Network

    Podgornik, Rudolf

    Polymers Pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore R. Podgornik, 1000 Ljubljana, Slovenia Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003, United States ABSTRACT: We investigate polymer partitioning from polymer

  4. POLYMER PROGRAM SEMINAR "Nanomanufacturing with Polymers"

    E-print Network

    Alpay, S. Pamir

    POLYMER PROGRAM SEMINAR "Nanomanufacturing with Polymers" Prof. Joey Mead University Lowell has developed a suite of processes to enable the nanomanufacturing of polymer based products of properties (e.g. biocompatibility, polarity, and modulus). Polymer materials can be used as substrates

  5. High Pressure Gas Permeation and Liquid Diffusion Studies of Coflon and Tefzel Thermoplastics. Revision

    NASA Technical Reports Server (NTRS)

    Morgan, G. J.; Campion, R. P.

    1997-01-01

    The life of fluid-carrying flexible or umbilical pipes during service at elevated temperatures and pressures depends inter alia on their resistance to attack by the fluids present and the rate at which these fluids are absorbed by the pipe lining materials. The consequences of fluid ingress into the thermoplastic lining could mean a) a reduction in its mechanical strength, to increase chances of crack formation and growth and thus a loss of integrity, b) the occurrence of permeation right through the lining material, with pressure build- up in the outer pipe wall construction (of flexible pipes) or chemical attack (from a hostile permeant) on outer layers of reinforcements. Therefore it is important within this project to have relevant permeation data for Coflon and Tefzel thermoplastics: the former is plasticised, the latter is not. A previous report (CAPP/M.2) described experimental equipment and techniques used by MERL when measuring high pressure (up to 5000 psi) gas permeation and liquid diffusion through thermoplastic samples cut from extruded bar or pipe, and provided the basic theory involved. Norsk Hydro are also performing gas permeation tests on pipe sections, at up to 100 bars (1450 psi) pressure or so, and reporting separately. Some comparisons between data from Norsk Hydro and MERL have been made herein. The tests should be considered as complementary, as the Norsk Hydro test has the obvious benefit of using complete pipe sections, whilst MERL can test at much higher pressures, up to 1000 bar if necessary. The sophisticated analytical measuring equipment of Norsk Hydro can distinguish the individual components of mixed gases and hence the various permeation-linked coefficients whereas MERL, in using pressure increase at constant volume to determine permeation rate, is limited to obtaining single gas data, or apparent (or representative) coefficients for a mixed gas as a whole. Except for the initial fluid diffusion data for Tefzel described in CAPP/M.2, the present report covers all aspects of fluid permeation and diffusion for Coflon and Tefzel, including all the pen-neation data accumulated in the project to date. Test gases have mainly been methane (CH4) and carbon dioxide (CO2). More high pressure (HP) gas permeation tests have been performed since the last issue of this report, most being concerned with changes in permeation characteristics brought about by ageing in various relevant fluids. This revision supersedes previous issues.

  6. Mathematical modeling of the in-mold coating process for injection-molded thermoplastic parts

    NASA Astrophysics Data System (ADS)

    Chen, Xu

    In-Mold Coating (IMC) has been successfully used for many years for exterior body panels made from compression molded Sheet Molding Compound (SMC). The coating material is a single component reactive fluid, designed to improve the surface quality of SMC moldings in terms of functional and cosmetic properties. When injected onto a cured SMC part, IMC cures and bonds to provide a pain-like surface. Because of its distinct advantages, IMC is being considered for application to injection molded thermoplastic parts. For a successful in mold coating operation, there are two key issues related to the flow of the coating. First, the injection nozzle should be located such that the thermoplastic substrate is totally covered and the potential for air trapping is minimized. The selected location should be cosmetically acceptable since it most likely will leave a mark on the coated surface. The nozzle location also needs to be accessible for easy of maintenance. Secondly, the hydraulic force generated by the coating injection pressure should not exceed the available clamping tonnage. If the clamping force is exceeded, coating leakage will occur. In this study, mathematical models for IMC flow on the compressible thermoplastic substrate have been developed. Finite Difference Method (FDM) is first used to solve the 1 dimensional (1D) IMC flow problem. In order to investigate the application of Control Volume based Finite Element Method (CV/FEM) to more complicated two dimensional IMC flow, that method is first evaluated by solving the 1D IMC flow problem. An analytical solution, which can be obtained when a linear relationship between the coating thickness and coating injection pressure is assumed, is used to verify the numerical results. The mathematical models for the 2 dimensional (2D) IMC flow are based on the generalized Hele-Shaw approximation. It has been found experimentally that the power law viscosity model adequately predicts the rheological behavior of the coating. The compressibility of the substrate is modeled by the 2-domain Tait PVT equation. CV/FEM is used to solve the discretized governing equations. A computer code has been developed to predict the fill pattern of the coating and the injection pressure. A number of experiments have been conducted to verify the numerical predictions of the computer code. It has been found both numerically and experimentally that the substrate thickness plays a significant role on the IMC fill pattern.

  7. Phthalocyanine polymers

    NASA Technical Reports Server (NTRS)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (inventors)

    1985-01-01

    A method of forming 4,4',4'',4''' -tetraamino phthalocyanines involves reducing 4,4',4'',4''' -tetranitro phthalocyanines, polymerizing the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerizing with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, varnishes, adhesives, and fibers.

  8. Polymer Coats Leads on Implantable Medical Device

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Langley Research Center s Soluble Imide (LaRC-SI) was discovered by accident. While researching resins and adhesives for advanced composites for high-speed aircraft, Robert Bryant, a Langley engineer, noticed that one of the polymers he was working with did not behave as predicted. After putting the compound through a two-stage controlled chemical reaction, expecting it to precipitate as a powder after the second stage, he was surprised to see that the compound remained soluble. This novel characteristic ended up making this polymer a very significant finding, eventually leading Bryant and his team to win several NASA technology awards, and an "R&D 100" award. The unique feature of this compound is the way that it lends itself to easy processing. Most polyimides (members of a group of remarkably strong and incredibly heat- and chemical-resistant polymers) require complex curing cycles before they are usable. LaRC-SI remains soluble in its final form, so no further chemical processing is required to produce final materials, like thin films and varnishes. Since producing LaRC-SI does not require complex manufacturing techniques, it has been processed into useful forms for a variety of applications, including mechanical parts, magnetic components, ceramics, adhesives, composites, flexible circuits, multilayer printed circuits, and coatings on fiber optics, wires, and metals. Bryant s team was, at the time, heavily involved with the aircraft polymer project and could not afford to further develop the polymer resin. Believing it was worth further exploration, though, he developed a plan for funding development and submitted it to Langley s chief scientist, who endorsed the experimentation. Bryant then left the high-speed civil transport project to develop LaRC-SI. The result is an extremely tough, lightweight thermoplastic that is not only solvent-resistant, but also has the ability to withstand temperature ranges from cryogenic levels to above 200 C. The thermoplastic s unique characteristics lend it to many commercial applications; uses that Bryant believed would ultimately benefit industry and the Nation. "LaRC-SI," he explains, "is a product created in a government laboratory, funded with money from the tax-paying public. What we discovered helps further the economic competitiveness of the United States, and it was our goal to initiate the technology transfer process to ensure that our work benefited the widest range of people." Several NASA centers, including Langley, have explored methods for using LaRC-SI in a number of applications from radiation shielding and as an adhesive to uses involving replacement of conventional rigid circuit boards. In the commercial realm, LaRC-SI can now be found in several commercial products, including the thin-layer composite unimorph ferroelectric driver and sensor (THUNDER) piezoelectric actuator, another "R&D 100" award winner (Spinoff 2005).

  9. Laser Surface Pre-treatment of Aluminium for Hybrid Joints with Glass Fibre Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Heckert, André; Zaeh, Michael F.

    Lightweight construction is a major trend in the automotive industry. Theconnection of fibre reinforced plastics with aluminium is consequently seen as promising prospect. In this regard, thermal joining can be applied for bonding of such hybrid joints. But in order to create a load bearing metal plastic joint, the surface of the metal has to be pre-treated. Recent research has shown that with laser surface pre-treatment high joint strengths are obtained. Yet there are a variety of laser sources and manufacturable surface topographies with structure sizes ranging from macroscopic to nanoscopic profiles. Within this work,macroscopic, microscopic and nanoscopic laser processed structures are created on aluminium and consequently joined to glass fibre reinforced thermoplastics of different fibre length and fibre content. High shear tensile strengths of up to 42 N/mm2 were obtained depending on the allocated material and the surface pre-treatment.

  10. Biocompatibility evaluation of a thermoplastic rubber for wireless telemetric intracranial pressure sensor coating.

    PubMed

    Yang, Jun; Charif, Andrea C; Puskas, Judit E; Phillips, Hannah; Shanahan, Kaitlyn J; Garsed, Jessica; Fleischman, Aaron; Goldman, Ken; Luebbers, Matthew T; Dombrowski, Stephen M; Luciano, Mark G

    2015-05-01

    This study investigated the biocompatibility of the experimental thermoplastic rubber Arbomatrix(™) that will be used as the protective coating on a novel intracranial pressure (ICP) sensor silicon chip. Arbomatrix(™) was benchmarked against biocompatible commercial silicone rubber shunt tubing in the brain via a rat model with 60-day implant duration. A bare silicon chip was also implanted. The results showed similar cellular distribution in the brain-implant boundary and surrounding tissues. Quantitative analysis of neuron and glia density did not show significant difference between implants. Through histological and immunohistochemical evaluation we conclude that Arbomatrix(™) is well tolerated by the brain. Due to its exceptional barrier properties Arbomatrix(™) has already been shown to be an excellent protective coating for new ICP monitoring chip. PMID:25688030

  11. Factors influencing the Mode I interlaminar fracture toughness of a rubber toughened thermoplastic matrix composite

    NASA Technical Reports Server (NTRS)

    Parker, D. S.; Yee, A. F.

    1989-01-01

    The use of a rubber modified thermoplastic resin has been investigated as a method to improve the Mode I interlaminar fracture toughness of a unidirectional continuous carbon fiber composite. Test results show that the improvement in the fracture toughness is less than expected due to rubber particle agglomeration, solvent and molding induced crystallization of the matrix and poor fiber/matrix adhesion. The plastic zone in composites utilizing tough matrices can extend well beyond a single interfibrillar spacing. However, the development of the plastic zone is limited due to the failure of the fiber/matrix interface. In order to fully evaluate the potential of tough composites using toughened matrices, any improvement made in the matrix toughness must be coupled with improvements in the fiber/matrix adhesion.

  12. Development of an impact- and solvent-resistant thermoplastic composite matrix, phase 3

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    The polyimide from BTDA 1,6-hexanediamine and m-phenylenediamine was selected from a prior study for the present study. Methods to prepare prepreg which would provide low void composites at low molding pressures from the thermoplastic polyimide were studied. Cresol solutions of the polyimide were applied to a balanced weave carbon fabric and the cresol removed prior to composite molding. Low void composites were prepared from smoothed prepregs at high pressures (34.5 MPa) and temperatures as low as 260 C. Lower molding pressures lead to higher void composites. Need for a lower melt viscosity in the neat resin is suggested as a requirement to achieve low void composites at low pressures. Some mechanical properties are included.

  13. Influence of thermal aging on tensile and creep behavior of thermoplastic polyurethane

    NASA Astrophysics Data System (ADS)

    Boubakri, A.; Haddar, N.; Elleuch, K.; Bienvenu, Y.

    2011-10-01

    Changes in mechanical and physical properties of polyurethane thermoplastic during aging at 70 °C and 90 °C were investigated. The loss weight response was analyzed by gravimetric measurements under these temperatures. Changes in appearance and morphology of TPU after thermal aging were revealed by optical microscopy. The prolongation of the thermal exposure time, up to 270 days, leads to a progressive increase in tensile strength. In fact, elastic modulus and stress at 200% of strain were increased with thermal exposure time. These results can be explained by the increase of thermal stability due to the increase of material rigidity and the decrease in chain mobility. The evolution of the mechanical properties from tensile tests seems to be well correlated to the creep behavior. Finally, Scanning Electron Microscopy (SEM) revealed the modification of TPU morphology fracture surface after thermal aging.

  14. From Process Modeling to Elastic Property Prediction for Long-Fiber Injection-Molded Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Frame, Barbara J.; Phelps, Jay; Tucker III, Charles L.; Bapanapalli, Satish K.; Holbery, James D.; Smith, Mark T.

    2007-09-13

    This paper presents an experimental-modeling approach to predict the elastic properties of long-fiber injection-molded thermoplastics (LFTs). The approach accounts for fiber length and orientation distributions in LFTs. LFT samples were injection-molded for the study, and fiber length and orientation distributions were measured at different locations for use in the computation of the composite properties. The current fiber orientation model was assessed to determine its capability to predict fiber orientation in LFTs. Predicted fiber orientations for the studied LFT samples were also used in the calculation of the elastic properties of these samples, and the predicted overall moduli were then compared with the experimental results. The elastic property prediction was based on the Eshelby-Mori-Tanaka method combined with the orientation averaging technique. The predictions reasonably agree with the experimental LFT data

  15. Injection-Molded Long-Fiber Thermoplastic Composites: From Process Modeling to Prediction of Mechanical Properties

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Jin, Xiaoshi; Tucker III, Charles L.; Costa, Franco

    2013-12-18

    This article illustrates the predictive capabilities for long-fiber thermoplastic (LFT) composites that first simulate the injection molding of LFT structures by Autodesk® Simulation Moldflow® Insight (ASMI) to accurately predict fiber orientation and length distributions in these structures. After validating fiber orientation and length predictions against the experimental data, the predicted results are used by ASMI to compute distributions of elastic properties in the molded structures. In addition, local stress-strain responses and damage accumulation under tensile loading are predicted by an elastic-plastic damage model of EMTA-NLA, a nonlinear analysis tool implemented in ABAQUS® via user-subroutines using an incremental Eshelby-Mori-Tanaka approach. Predicted stress-strain responses up to failure and damage accumulations are compared to the experimental results to validate the model.

  16. Thermoplastic deformation of silicon surfaces induced by ultrashort pulsed lasers in submelting conditions

    SciTech Connect

    Tsibidis, G. D. [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology (FORTH), N. Plastira 100, Vassilika Vouton, 70013, Heraklion, Crete (Greece); Stratakis, E. [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology (FORTH), N. Plastira 100, Vassilika Vouton, 70013, Heraklion, Crete (Greece); Department of Materials Science and Technology, University of Crete, 710 03 Heraklion, Crete (Greece); Aifantis, K. E. [Laboratory of Mechanics and Materials, Aristotle University of Thessaloniki, GR-54006 Thessaloniki (Greece)

    2012-03-01

    A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation process. The evolution of the induced deformation field is described initially by adopting the differential equations of dynamic thermoelasticity while the onset of plastic yielding is described by the von Mises stress. Details of the resulting picometre sized crater, produced by irradiation with a single pulse, are discussed as a function of the imposed conditions and thresholds for the onset of plasticity are computed. Irradiation with multiple pulses leads to ripple formation of nanometre size that originates from the interference of the incident and a surface scattered wave. It is suggested that ultrafast laser induced surface modification in semiconductors is feasible in submelting conditions, and it may act as a precursor of the incubation effects observed at multiple pulse irradiation of materials surfaces.

  17. Development of a two-dimensional thermal model for the steady state thermoplastic pultrusion process

    NASA Astrophysics Data System (ADS)

    Ruan, Yimin; Liu, Joshua C.; Chesonis, D. C.; Carvell, Lee A.

    A two-dimensional steady state heat transfer model is developed in this report for the thermoplastic pultrusion process. In this model, the finite element method with a stream line diffusion approach is used. The stream line diffusion method will minimize the numerical oscillations when the pulling speed is high and the finite element mesh is coarse. The crystallization kinetics reported by Ozawa is employed to calculate the relative crystallinity and the heat released due to the crystallization process during cooling. It is assumed the taper angle of the consolidation die is small so that the pultrusion can be approximated as an orthotropic material. The volume fractions of void, matrix, and fiber are defined based on material densities and consolidation strains. Examples for pultrusion of APC-2 are studied using this finite element model.

  18. Measurement of internal die pressure distributions during pultrusion of thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Fanucci, Jerome P.; Nolet, Stephen C.; Koppernaes, Christian; Kim, Young R.

    This paper describes the development and use of a thin, disposable pressure sensor designed specifically for monitoring pointwise through-the-thickness consolidation forces developed during composite processing. The unique postage stamp-sized sensor (11.1 mm diameter active gage area and 0.31 mm thickness) can be placed directly at points in or on a laminate where pressure data is desired. The sonsor's small dimensions and low cost permit it to be treated as a disposable item in aerospace and other composite fabrication applications. This paper will illustrate the use of the sensor as a means of measuring the pressures developed inside a die during the pultrusion of a graphite/ULTEM thermoplastic structure, as well as with other pultrusion processing examples.

  19. Manufacturing and Process-based Property Analysis of Textile-Reinforced Thermoplastic Spacer Composites

    NASA Astrophysics Data System (ADS)

    Hufenbach, Werner; Adam, Frank; Füßel, René; Krahl, Michael; Weck, Daniel

    2012-12-01

    Novel woven spacer fabrics based on hybrid yarns are suitable for an efficient fabrication of three-dimensional composite structures in high volume production. In this paper, an innovative manufacturing process with short cycle times and high automatisation is introduced for textile-reinforced thermoplastic spacer structures suited for bending load cases. The different process steps hybrid yarn fabrication, weaving technology for three-dimensional textile preforms and consolidation with unique kinematics and hot pressing technology are described in detail. The bending properties of the manufactured spacer structures are evaluated by means of experiments as well as finite element simulations. Numerical parametric studies are performed in order to validate the influence of manufacturing tolerances on the bending stiffness of the spacer structures.

  20. Effect of thermoplastic coating on interfacial adhesion of oxygen-plasma-pretreated PBO/PPESK composites

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyi; Chen, Ping; Han, Debin; Yu, Qi; Ding, Zhenfeng; Zhu, Xiuling

    2013-02-01

    To improve the interfacial adhesion of PBO/PPESK composite, thermoplastic resins were coated onto the fiber surface after plasma pretreatment. Two coating resins applied in this study were chemically linked with the plasma pretreated fibers, which was confirmed by X-ray photoelectron spectroscopy. The fiber surface morphologies and wettability were analyzed by scanning electron microscope (SEM) and dynamic contact angle analysis, respectively. The interfacial adhesion performance of the PBO fiber-reinforced PPESK composite was measured by interlaminar shear strength (ILSS) and water absorption tests. Fracture mechanisms of the composites were examined by SEM. The results indicated that after coating the surface wettability was improved and the ILSS had an increment of 80.8% for phenolphthalein poly (ether ketone) coating and 30.3% for phenolphthalein poly (ether sulfone) coating.

  1. 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. PMID:24454376

  2. Impact-damaged graphite-thermoplastic trapezoidal-corrugation sandwich and semi-sandwich panels

    NASA Technical Reports Server (NTRS)

    Jegley, D.

    1993-01-01

    The results of a study of the effects of impact damage on compression-loaded trapezoidal-corrugation sandwich and semi-sandwich graphite-thermoplastic panels are presented. Sandwich panels with two identical face sheets and a trapezoidal corrugated core between them, and semi-sandwich panels with a corrugation attached to a single skin are considered in this study. Panels were designed, fabricated and tested. The panels were made using the manufacturing process of thermoforming, a less-commonly used technique for fabricating composite parts. Experimental results for unimpacted control panels and panels subjected to impact damage prior to loading are presented. Little work can be found in the literature about these configurations of thermoformed panels.

  3. EMAA thermoplastic powder coatings: Shop and field application of powder coatings for aggressive environments

    SciTech Connect

    Loustaunau, P.J.; Horton, D. [Plastic FLAMECOAT Systems, Inc., League City, TX (United States)

    1994-12-31

    This paper deals with how Ethylene Methacrylic Acid thermoplastic powder coatings are allowing asset owners to meet tightening environmental regulations while solving some of their most difficult coating problems. It discusses the versatility of traditional shop application methods and field application/repair methods in the rail and water/waste water treatment areas. EMAA coatings typically perform well in aggressive environments due to their high flexibility and impact resistance. The material`s inherent toughness also provides for excellent abrasion resistance. EMAA demonstrates excellent resistance to chemical attack and is highly resistant to permeation by liquids. Because some aromatic, cyclic and higher aliphatic hydrocarbon solvents may cause swelling and permeate through the coating, caution should be used in immersion applications with this group of solutions.

  4. Influence of Molecular Weight on the Mechanical Performance of a Thermoplastic Glassy Polyimide

    NASA Technical Reports Server (NTRS)

    Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.; Hinkley, Jeffrey A.

    1999-01-01

    Mechanical Testing of an advanced thermoplastic polyimide (LaRC-TM-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The physical characterization, elastic properties and notched tensile strength were all determined as a function of molecular weight and test temperature. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. A critical molecular weight (Mc) was observed to occur at a weight-average molecular weight (Mw) of approx. 22000 g/mol below which, the notched tensile strength decreases rapidly. This critical molecular weight transition is temperature-independent. Furthermore, inelastic analysis showed that low molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. The microstructural images supported these findings.

  5. Modified thermoplastic plate: a new proposal for correction of exaggerated overbite in mixed dentition.

    PubMed

    Pithon, M M; Alves, L P; Alves, G O; Teixeira, N S

    2012-01-01

    Exaggerated overbite can be corrected by several treatment modalities. As the primary objective is to correct the problem by addressing its root cause, treatment options are closely related to etiology. Therefore, the main treatment strategies are: the extrusion of posterior teeth, intrusion of teeth (maxillary/mandibular) or the combination of these. The purpose of this paper is to describe the fabrication of a modified thermoplastic plate (MTP) for correction of exaggerated overbite in mixed dentition and describe a clinical case treated with this device. MTP favored the extrusion of posterior teeth, in addition to being shown to be a device that was easy to manufacture and effective in the treatment of excessive overbite, enabling patients to return to normal condition during the development of occlusion. PMID:23342576

  6. Fibre-reinforced composite structures based on thermoplastic matrices with embedded piezoceramic modules

    NASA Astrophysics Data System (ADS)

    Hufenbach, Werner A.; Modler, Niels; Winkler, Anja; Ilg, Juergen; Rupitsch, Stefan J.

    2014-02-01

    The paper presents recent developments for the integration of piezoceramic modules into fibre-reinforced composite structures based on thermoplastic matrices. An adapted hot pressing technology is conceptualized that allows for material homogeneous integration of the active modules. The main focus of this contribution is on the development of a robust and continuous manufacturing process of such novel active composites as well as on the operational testing of the produced samples. Therefore, selected specimens are manufactured as bending beams and investigated by means of electrical impedance measurements, modal analysis and structural excitation tests. In particular, the functionality of representative specimens is characterized based on frequency as well as spatially resolved deflection measurements. Moreover, the mentioned samples are compared to non-integrated piezoceramic modules and to equivalent passive reinforced composite structures.

  7. Detection of bromine in thermoplasts from consumer electronics by laser-induced plasma spectroscopy

    NASA Astrophysics Data System (ADS)

    Radivojevic, I.; Niessner, R.; Haisch, C.; Florek, S.; Becker-Ross, H.; Panne, U.

    2004-03-01

    Laser-induced plasma spectroscopy (LIPS) was utilized for the detection of bromine in thermoplasts with flame retardants. For detection of bromine in the VUV region and UV/Vis/NIR region, two different experimental set-ups were realized. A time-resolved study of the plasma emission indicated that the detection of atomic Br lines in the VUV was complicated by the formation of molecular oxygen in the plasma. However, the limit of detection for bromine in the VUV region at 130.99 nm was significantly improved compared to the detection limit determined in the NIR region. With an optical path purged with argon, VUV-LIPS is feasible for process analysis.

  8. Horse chestnut (Aesculus hippocastanum L.) starch: Basic physico-chemical characteristics and use as thermoplastic material.

    PubMed

    Castaño, J; Rodríguez-Llamazares, S; Contreras, K; Carrasco, C; Pozo, C; Bouza, R; Franco, C M L; Giraldo, D

    2014-11-01

    Starch isolated from non-edible Aesculus hippocastanum seeds was characterized and used for preparing starch-based materials. The apparent amylose content of the isolated starch was 33.1%. The size of starch granules ranged from 0.7 to 35 ?m, and correlated with the shape of granules (spherical, oval and irregular). The chain length distribution profile of amylopectin showed two peaks, at polymerization degree (DP) of 12 and 41-43. Around 53% of branch unit chains had DP in the range of 11-20. A. hippocastanum starch displayed a typical C-type pattern and the maximum decomposition temperature was 317 °C. Thermoplastic starch (TPS) prepared from A. hippocastanum with glycerol and processed by melt blending exhibited adequate mechanical and thermal properties. In contrast, plasticized TPS with glycerol:malic acid (1:1) showed lower thermal stability and a pasty and sticky behavior, indicating that malic acid accelerates degradation of starch during processing. PMID:25129797

  9. Biocompatibility and fatigue properties of polystyrene-polyisobutylene-polystyrene, an emerging thermoplastic elastomeric biomaterial.

    PubMed

    El Fray, Miroslawa; Prowans, Piotr; Puskas, Judit E; Altstädt, Volker

    2006-03-01

    This paper will discuss the biocompatibility and dynamic fatigue properties of polystyrene-b-polyisobutylene-b-polystyrene thermoplastic elastomer with 30 wt % polystyrene (SIBS30), an emerging FDA-approved biomaterial. SIBS30 is a very soft, transparent biomaterial resembling silicone rubber, with superior mechanical properties. Using the hysteresis method adopted for soft biomaterials, the dynamic fatigue properties of SIBS30 were found to be between those of polyurethane and silicone rubber, with fatigue life twice as long as that of silicone. Under single load testing (SLT, 1.25 MPa), SIBS30 displayed less than half the dynamic creep compared to silicone, both in air and in vitro (37 degrees C, simulated body fluid). Hemolysis and 30- and 180-day implantation studies revealed excellent biocompatibility of the new biomaterial. The results presented in this paper indicate that, in comparison with silicone rubber, SIBS30 has similar biocompatibility and superior dynamic fatigue properties. PMID:16529422

  10. A constitutive model for AS4/PEEK thermoplastic composites under cyclic loading

    NASA Technical Reports Server (NTRS)

    Rui, Yuting; Sun, C. T.

    1990-01-01

    Based on the basic and essential features of the elastic-plastic response of the AS4/PEEK thermoplastic composite subjected to off-axis cyclic loadings, a simple rate-independent constitutive model is proposed to describe the orthotropic material behavior for cyclic loadings. A one-parameter memory surface is introduced to distinguish the virgin deformation and the subsequent deformation process and to characterize the loading range effect. Cyclic softening is characterized by the change of generalized plastic modulus. By the vanishing yield surface assumption, a yield criterion is not needed and it is not necessary to consider loading and unloading separately. The model is compared with experimental results and good agreement is obtained.

  11. 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. PMID:25545630

  12. Post-crosslinking modification of thermoplastic starch/PVA blend films by using sodium hexametaphosphate.

    PubMed

    Liu, Ziqin; Dong, Yan; Men, Haitao; Jiang, Man; Tong, Jin; Zhou, Jiang

    2012-06-20

    Thermoplastic starch (TPS)/poly (vinyl alcohol) (PVA) blend films were post-treated by crosslinking through soaking the films in sodium carbonate aqueous solution and sodium hexametaphosphate aqueous solution sequentially and then heating. The effects of the concentrations of the sodium carbonate aqueous solution and the sodium hexametaphosphate aqueous solution, soaking time, heating temperature and time on the properties of the TPS/PVA blend films were investigated. It was found that the crosslinking modification significantly reduced the moisture sensitivity of the TPS/PVA blend films, i.e., lowered the equilibrium moisture content of the blend films, increased the tensile strength and Young's modulus but decreased the elongation at break of the blend films. The described method could be used for post-treating TPS/PVA based products to optimize their properties. PMID:24750746

  13. 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

  14. Mechanical properties of long carbon fiber reinforced thermoplastic (LFT) at elevated temperature

    NASA Astrophysics Data System (ADS)

    Wang, Qiushi

    Long fiber reinforced thermoplastics (LFT) possess high specific modulus and strength, superior damage tolerance and fracture toughness and have found increasing use in transportation, military, and aerospace applications. However, one of the impediments to utilizing these materials is the lack of performance data in harsh conditions, especially at elevated temperature. In order to quantify the effect of temperature on the mechanical properties of carbon fiber reinforced thermoplastic composites, carbon fiber PAA composite plates containing 20% and 30% carbon fiber were produced using extrusion/compression molding process and tested at three representative temperatures, room temperature (RT 26°C), middle temperature (MID 60°C) and glass transition temperature (Tg 80°C). A heating chamber was designed and fabricated for the testing at elevated temperature. As temperature increases, flexural modulus, flexural strength, tensile modulus and tensile strength decrease. The highest reduction observed in stiffness (modulus) values of 30% CF/PAA at Tg in the 00 orientation is 75%. The reduction values were larger for the transverse (perpendicular to flow direction) samples than the longitudinal (flow direction) samples. The property reduction in 30% CF/PAA is larger than 20% CF/PAA. Furthermore, an innovative method was developed to calculate the fiber content in carbon fiber reinforced composites by burning off the neat resin and sample in a tube furnace. This method was proved to be accurate (within 1.5 wt. % deviation) by using burning off data obtained from CF/Epoxy and CF/Vinyl Ester samples. 20% and 30% carbon/PAA samples were burned off and carbon fiber content was obtained using this method. The results of the present study will be helpful in determining the end-user applications of these composite materials. Keywords: Long Carbon Fibers, Elevated Temperature, Mechanical Properties, Burn off Test.

  15. Assessment of interfractional prostate motion in patients immobilized in the prone position using a thermoplastic shell

    PubMed Central

    Ikeda, Itaru; Mizowaki, Takashi; Sawada, Yohei; Nakata, Manabu; Norihisa, Yoshiki; Ogura, Masakazu; Hiraoka, Masahiro

    2014-01-01

    The aim of this study was to evaluate the interfractional prostate motion of patients immobilized in the prone position using a thermoplastic shell. A total of 24 patients with prostate calcifications detectable using a kilo-voltage X-ray image-guidance system (ExacTrac X-ray system) were examined. Daily displacements of the calcification within the prostate relative to pelvic bony structures were calculated by the ExacTrac X-ray system. The average displacement and standard deviation (SD) in each of the left–right (LR), anterior–posterior (AP), and superior–inferior (SI) directions were calculated for each patient. Based on the results of interfractional prostate motion, we also calculated planning target volume (PTV) margins using the van Herk formula and examined the validity of the PTV margin of our institute (a 9-mm margin everywhere except posteriorly, where a 6-mm margin was applied). In total, 899 data measurements from 24 patients were obtained. The average prostate displacements ± SD relative to bony structures were 2.8 ± 3.3, ?2.0 ± 2.0 and 0.2 ± 0.4 mm, in the SI, AP and LR directions, respectively. The required PTV margins were 9.7, 6.1 and 1.4 mm in the SI, AP and LR directions, respectively. The clinical target volumes of 21 patients (87.5%) were located within the PTV for 90% or more of all treatment sessions. Interfractional prostate motion in the prone position with a thermoplastic shell was equivalent to that reported for the supine position. The PTV margin of our institute is considered appropriate for alignment, based on bony structures. PMID:23860549

  16. In vitro retention of a new thermoplastic titratable mandibular advancement device

    PubMed Central

    Braem, Marc

    2015-01-01

    Oral appliance (OA) therapy with a mandibular advancement device (OAm) is a non-invasive, alternative approach to maintaining upper airway patency. The main requirement for an OAm to be effective is the adequate retention on the teeth while the patient is asleep. We evaluated the retentive forces of a new low-cost, customizable, titratable, thermoplastic OAm (BluePro ®; BlueSom, France). Dental impressions and casts were made for one patient with complete upper and lower dental arches including the third molars and class II bite proportions. A setup based on Frasaco ANA-4 models was also used. Two protrusive positions of the mandible were investigated: 3 mm and 8 mm, representing respectively 25% and 65% of the maximal protrusion. The forces required to remove the BluePro ® device from the carriers were recorded continuously over 730 cycles (=365 days, twice a day) to simulate 1 year of clinical use. At 8 mm protrusion the BluePro ® device showed retentive forces of ~27N. There was a slight but non-significant decrease in retentive forces in the tests on the epoxified carriers which was not found on the ANA-4 carriers. There were no significant differences between the carriers as a function of protrusion. The BluePro ® device tested in the present study possesses sufficient retention forces to resist initial jaw opening forces and full mouth opening forces estimated to be ~20N. It could therefore broaden the indications for use of thermoplastic OAms. It could provide a temporary OAm while a custom-made OAm is being manufactured or repaired. Patients could be provided with a low-cost try-out device capable of reliable titration, providing an indication of effectiveness and of patient acceptance of an OAm, although the effect of device shape and size on therapeutic outcome is not yet known. Finally it could provide an affordable OAm solution in resource-restricted healthcare settings.

  17. Simulation and experimentation in melt spinning of liquid crystalline polymer reinforced composite fiber

    NASA Astrophysics Data System (ADS)

    He, Xiaojun

    Liquid crystalline polymers (LCPs) are a relatively new class of materials. These polymers usually consist of rigid rod-like molecular chains and they are capable of forming highly-oriented structures. Blending conventional thermoplastic polymers with LCPs produces fibrillar LCP structure that serve as the reinforcing component. The properties of the blends are affected by the size, shape and distribution of the LCPs in the matrix polymer, which in turn are related to the processing conditions which include the blend composition, the extrusion conditions and the viscosity ratio of the component polymers. We report the results of our study on the properties and morphology development of an in-situ composite based on the thermotropic liquid crystalline polymer (TLCP), Vectra. A mathematical model is also developed to simulate the deformation of TLCP during isothermal melt spinning. The simulation results are evaluated by comparing the model prediction of the rheological properties of the blend with those calculated from on-line measurement data. The model implication is also discussed in view of guiding the design of TLCP reinforcing composites.

  18. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

  19. The role of nanoparticle synergies in modifying the thermal properties of biodegradable polymer blends

    NASA Astrophysics Data System (ADS)

    Yang, Kai; He, Shan; Davis, Rachel; Rafailovich, Miriam; Kashiwagi, Takashi

    2012-02-01

    Most of thermoplastic polymers are brittle, when sufficient amounts are added to get flame retardant properties.Furthermore, melt-blending starch with other biodegradable polymers is difficult since very few polymers are compatible with starches.We have developed a new nanoparticles where resorcinol diphenyl phosphates (RDP) is used to modify the surface energy, allowing the particles to be dispersed within polymer.When multiple types of particles share the same coating,they can be melt blended simultaneously and synergies can be achieved, imparting properties to the nanocomposite, which cannot be achieved by any single additive. Here we show that RDP modified starch, can be extruded together with the biodegradable polymers,Ecoflex and polylactic acid,to produce flame retardant nanocomposites which can pass the UL-94-V0 test.TEM images of the blend show that the RDP-coated starch particles were well dispersed within the polymer matrix providing the flame retardant properties,while the RDP clays are reducing the interfacial tension and contributing to compatibilization. Nanomechanical measurements of the chars remaining after cone calorimetric measurements indicate that maintaining flexibility of the chars may be an additional factor in achieving good flame retardant properties.

  20. A PDMS pinch-valve module embedded in rigid polymer lab chips for on-chip flow regulation

    NASA Astrophysics Data System (ADS)

    Browne, Andrew W.; Hitchcock, Kathryn E.; Ahn, Chong H.

    2009-11-01

    A new dead-volume-free PDMS pinch microvalve has been designed, fabricated and characterized in this work for valving and flow regulation on rigid polymer lab chips as an embedded modular platform. The pinch microvalve is operated by compressing a microfabricated flexible channel with an external actuation force. The assembly of modular PDMS pinch microvalves within rigid thermoplastic microfluidic devices provides numerous benefits in realizing hybrid polymer lab chips with functionality to precisely regulate flow. Flow rates of the developed pinch microvalve were characterized with respect to the pinch valve channel dimension and the pinching displacement distance applied to the valve. Finally, a microfluidic system with a single channel that branches into four pinch-valved channels was realized and a novel scheme for simultaneously actuating all four valves with a single actuator was demonstrated. The microfluidic PDMS pinch valves developed in this work will have a variety of applications in microfluidic systems developed in rigid polymers.