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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

  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. Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

  4. Bonding thermoplastic polymers

    DOEpatents

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

    2008-06-24

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

  5. 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.

  6. Tough, High-Performance, Thermoplastic Addition Polymers

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  7. Method of forming a foamed thermoplastic polymer

    DOEpatents

    Duchane, David V.; Cash, David L.

    1986-01-01

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

  8. Method of forming a foamed thermoplastic polymer

    DOEpatents

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

    1984-11-21

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

  9. Dynamically cured thermoplastic olefin polymers

    SciTech Connect

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

    1986-08-19

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

  10. 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.

  11. 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

  12. 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

  13. 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

  14. Nanotube reinforced thermoplastic polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Shofner, Meisha Lei

    The inherent high strength, thermal conductivity, and electrical conductivity make nanotubes attractive reinforcements for polymer matrix composites. However, the structure that makes them desirable also causes highly anisotropic properties and limited reactivity with other materials. This thesis isolates these problems in two separate studies aimed at improving mechanical properties with single wall nanotube (SWNT) reinforced thermoplastic polymer composites. The two studies demonstrate the effect of solid freeform fabrication (SFF) and chemical functionalization on anisotropy and limited reactivity, respectively. Both studies showed mechanical property improvements. The alignment study demonstrates a maximum increase of 93% in tensile modulus with single wall nanotubes (SWNTs). The chemical functionalization study shows a larger increase in storage modulus for functionalized SWNTs as compared to purified SVWNTs with respective increases of 9% and 44% in storage modulus. Improved interfacial properties are also observed as a decrease in mechanical damping. Maximum property increases in composites are obtained when nanotubes are aligned, requiring additional processing consideration to the anisotropic structure. Melt spinning and extrusion processing effectively align nanotubes, but the end product of these techniques, composite fibers, requires further processing to be incorporated into finished parts. Extrusion-based SFF is a novel technique for processing nanotube reinforced composites because it allows for the direct fabrication of finished parts containing aligned nanotubes. SFF processing produces parts containing preferentially oriented nanotubes with improved mechanical properties when compared to isotropic composites. Functionalization of the nanotube surface disrupts the rope structure to obtain smaller ropes and promote further interfacial bonding. The chemically inert nature of nanotubes resulting from a structure containing few defects and the

  15. Drilling fluids based on a mixture of a sulfonated thermoplastic polymer and a sulfonated elastomeric polymer

    SciTech Connect

    Turner, S.R.; Lundberg, R.D.; Peiffer, D.G.; Thaler, W.A.; Walker, T.O.

    1984-01-10

    The present invention relates to mixtures of sulfonated thermoplastic polymers and sulfonated elastomeric polymers which function as viscosification agents when added to oil-based drilling muds which are the fluids used to maintain pressure, cool drill bits, and lift cuttings from the holes in the drilling operation for oil and gas wells. The sulfonated thermoplastic and elastomeric polymers both have about 5 to about 200 meq. of sulfonate groups per 100 grams of the sulfonated thermoplastic or elastomeric polymers, wherein the sulfonated groups are neutralized with a metallic cation or an amine or ammonium counterion. A polar cosolvent can optionally be added to the mixture of oil drilling mud and sulfonated thermoplastic and elastomeric polymers, wherein the polar cosolvent increases the solubility of the sulfonated thermoplastic and elastomeric polymer in the oil drilling mud by decreasing the strong ionic interactions between the sulfonate groups of the sulfonated polymers.

  16. Photoinitiated grafting of porous polymer monoliths and thermoplastic polymers for microfluidic devices

    DOEpatents

    Frechet, Jean M. J.; Svec, Frantisek; Rohr, Thomas

    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.

  17. The analysis of thermoplastic characteristics of special polymer sulfur composite

    NASA Astrophysics Data System (ADS)

    Książek, Mariusz

    2016-07-01

    Specific chemical environments step out in the industry objects. Portland cement composites (concrete and mortar) were impregnated by using the special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot was applied as the industrial waste. Portland cement composites were made of the same aggregate, cement and water. The process of special polymer sulfur composite applied as the industrial waste is a thermal treatment process in the temperature of about 150-155°C. The result of such treatment is special polymer sulfur composite in a liquid state. This paper presents the plastic constants and coefficients of thermal expansion of special polymer sulfur composites, with isotropic porous matrix, reinforced by disoriented ellipsoidal inclusions with orthotropic symmetry of the thermoplastic properties. The investigations are based on the stochastic differential equations of solid mechanics. A model and algorithm for calculating the effective characteristics of special polymer sulfur composites are suggested. The effective thermoplastic characteristics of special polymer sulfur composites, with disoriented ellipsoidal inclusions, are calculated in two stages: First, the properties of materials with oriented inclusions are determined, and then effective constants of a composite with disoriented inclusions are determined on the basis of the Voigt or Rice scheme. A brief summary of new products related to special polymer sulfur composites is given as follows: Impregnation, repair, overlays and precast polymer concrete will be presented. Special polymer sulfur as polymer coating impregnation, which has received little attention in recent years, currently has some very interesting applications.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Mechanical properties of a new thermoplastic polymer orthodontic archwire.

    PubMed

    Varela, Juan Carlos; Velo, Marcos; Espinar, Eduardo; Llamas, Jose Maria; Rúperez, Elisa; Manero, Jose Maria; Javier Gil, F

    2014-09-01

    A new thermoplastic polymer for orthodontic applications was obtained and extruded into wires with round and rectangular cross sections. We evaluated the potential of new aesthetic archwire: tensile, three point bending, friction and stress relaxation behaviour, and formability characteristics were assessed. Stresses delivered were generally slightly lower than typical beta-titanium and nickel-titanium archwires. The polymer wire has good instantaneous mechanical properties; tensile stress decayed about 2% over 2h depending on the initial stress relaxation for up to 120h. High formability allowed shape bending similar to that associated with stainless steel wires. The friction coefficients were lower than the metallic conventional archwires improving the slipping with the brackets. This new polymer could be a good candidate for aesthetic orthodontic archwires. PMID:25063084

  3. 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.

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

    SciTech Connect

    Roggero, A.; Pedretti, U.; La Mantia, F.P.

    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.

  5. 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.

  6. Biodegradable polymer blends based on corn starch and thermoplastic chitosan processed by extrusion.

    PubMed

    Mendes, J F; Paschoalin, R T; Carmona, V B; Sena Neto, Alfredo R; Marques, A C P; Marconcini, J M; Mattoso, L H C; Medeiros, E S; Oliveira, J E

    2016-02-10

    Blends of thermoplastic cornstarch (TPS) and chitosan (TPC) were obtained by melt extrusion. The effect of TPC incorporation in TPS matrix and polymer interaction on morphology and thermal and mechanical properties were investigated. Possible interactions between the starch molecules and thermoplastic chitosan were assessed by XRD and FTIR techniques. Scanning Electron Microscopy (SEM) analyses showed a homogeneous fracture surface without the presence of starch granules or chitosan aggregates. Although the incorporation of thermoplastic chitosan caused a decrease in both tensile strength and stiffness, films with better extensibility and thermal stability were produced. PMID:26686150

  7. 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.

  8. 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.

  9. Intrinsically Conductive Polymer Fibers from Thermoplastic trans-1,4-Polyisoprene.

    PubMed

    Han, Peng; Zhang, Xiaohong; Qiao, Jinliang

    2016-05-17

    Herein, we report a new strategy to prepare conductive polymer fibers to overcome the insurmountable weakness of current conductive polymer fibers. First, special thermoplastic polymers are processed into polymer fibers using a conventional melt-spinning process, and then the nonconductive polymer fibers are converted into intrinsically conductive polymer fibers. Using this new strategy, intrinsically conductive polymer fibers have been prepared by melt spinning low-cost thermoplastic trans-1,4-polyisoprene and doping with iodine, which can be as fine as 0.01 mm, and the resistivity can be as low as 10(-2) Ω m. Moreover, it has been found that drawing can improve the orientation of trans-1,4-polyisoprene crystals in the fibers and, thus, the conductivity of the conductive polymer fibers. Therefore, conductive fibers with excellent conductivities can be prepared by large drawing ratios before doping. Such conductive polymer fibers with low cost could be used in textile, clothing, packing, and other fields, which would benefit both industry and daily life. The newly developed method also allows one to produce conductive polymers of any shape besides fibers for antistatic or conductive applications. PMID:27135825

  10. 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

  11. Noncontact microembossing technology for fabricating thermoplastic optical polymer microlens array sheets.

    PubMed

    Chang, Xuefeng; Xie, Dan; 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

  12. Thermochemical and flammability properties of some thermoplastic and thermoset polymers - A review

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.

    1978-01-01

    The thermochemical and flammability properties of thermoplastic and thermoset polymers are discussed. The results of a thermogravimetric analysis of the polymers conducted on a DuPont 950 thermogravimetric analyzer using both nitrogen and air atmospheres are presented. Experimental data on smoke evolution are given, and the methodology for assessing the relative toxicity of the pyrolysis effluents is described. The values obtained from the flammability tests are compared with the stoichiometric char yield, and it is shown that the ignition tendency of the polymers is a linear function of the resin char yield

  13. 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

  14. A Mechanically Strong, Highly Stable, Thermoplastic, and Self-Healable Supramolecular Polymer Hydrogel.

    PubMed

    Dai, Xiyang; Zhang, Yinyu; Gao, Lina; Bai, Tao; Wang, Wei; Cui, Yuanlu; Liu, Wenguang

    2015-06-17

    Polymerization of glycinamide-conjugated monomer alone in concentrated aqueous solution enables facile formation of a mechanically strong and a highly stable supramolecular polymer (SP) hydrogel because of the cooperatively hydrogen-bonded crosslinking and strengthening effect from dual amide motifs. This SP hydrogel exhibits thermoplastic processability, injectability, and self-reparability because of the dynamic destruction and reconstruction of hydrogen bonds in response to temperature change. PMID:25946310

  15. 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

  16. Shape-Controlled Metal-Metal and Metal-Polymer Janus Structures by Thermoplastic Embossing.

    PubMed

    Hasan, Molla; Kahler, Niloofar; Kumar, Golden

    2016-05-01

    We report the fabrication of metal-metal and metal-polymer Janus structures by embossing of thermoplastic metallic glasses and polymers. Hybrid structures with controllable shapes and interfaces are synthesized by template-assisted embossing. Different manufacturing strategies such as co-embossing and additive embossing are demonstrated for joining the materials with diverse compositions and functionalities. Structures with distinct combinations of properties such as hydrophobic-hydrophilic, opaque-transparent, insulator-conductor, and nonmagnetic-ferromagnetic are produced using this approach. These anisotropic properties are further utilized for selective functionalization of Janus structures. PMID:27064306

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

    SciTech Connect

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

    2012-01-01

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

  18. Ex Situ Integration of Multifunctional Porous Polymer Monoliths into Thermoplastic Microfluidic Chips

    PubMed Central

    Kendall, Eric L.; Wienhold, Erik; Rahmanian, Omid D.; DeVoe, Don L.

    2014-01-01

    A unique method for incorporating functional porous polymer monolith elements into thermoplastic microfluidic chips is described. Monolith elements are formed in a microfabricated mold, rather than within the microchannels, and chemically functionalized off chip before insertion into solvent-softened thermoplastic microchannels during chip assembly. Because monoliths may be trimmed prior to final placement, control of their size, shape, and uniformity is greatly improved over in-situ photopolymerization methods. A characteristic trapezoidal profile facilitates rapid insertion and enables complete mechanical anchoring of the monolith periphery, eliminating the need for chemical attachment to the microchannel walls. Off-chip processing allows the parallel preparation of monoliths of differing compositions and surface chemistries in large batches. Multifunctional flow-through arrays of multiple monolith elements are demonstrated using this approach through the creation of a fluorescent immunosensor with integrated controls, and a microfluidic bubble separator comprising a combination of integrated hydrophobic and hydrophilic monolith elements. PMID:25018587

  19. Review of modern techniques to generate antireflective properties on thermoplastic polymers.

    PubMed

    Schulz, Ulrike

    2006-03-01

    Modern optical applications need solutions for providing polymer surfaces with antireflective properties. The problems involved in coating comprise thermal limitations, incompatible mechanical properties of coating and substrate materials, and interaction between polymers and plasma. As an alternative for coating, antireflective properties on polymers can also be obtained by hot embossing or by ion etching of surface structures. My objective is to provide the criteria for choosing suitable deposition or structuring methods based on an understanding of plasma-, radiation-, and ion-induced surface phenomena; material compatibility; mechanical and environmental performance; and cost issues. The potential to produce antireflective interference coatings is documented for plasma-enhanced physical- and chemical-vapor-deposition methods, including modern hybrid techniques, as well as for solgel wet-chemical processes. The review about state-of-the-art coatings focuses on the thermoplastic acrylic, polycarbonate, and cycloolefin polymers. PMID:16539270

  20. Review of modern techniques to generate antireflective properties on thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Schulz, Ulrike

    2006-03-01

    Modern optical applications need solutions for providing polymer surfaces with antireflective properties. The problems involved in coating comprise thermal limitations, incompatible mechanical properties of coating and substrate materials, and interaction between polymers and plasma. As an alternative for coating, antireflective properties on polymers can also be obtained by hot embossing or by ion etching of surface structures. My objective is to provide the criteria for choosing suitable deposition or structuring methods based on an understanding of plasma-, radiation-, and ion-induced surface phenomena; material compatibility; mechanical and environmental performance; and cost issues. The potential to produce antireflective interference coatings is documented for plasma-enhanced physical- and chemical-vapor-deposition methods, including modern hybrid techniques, as well as for solgel wet-chemical processes. The review about state-of-the-art coatings focuses on the thermoplastic acrylic, polycarbonate, and cycloolefin polymers.

  1. 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.

  2. Thermoplastic polymer patterning without residual layer by advanced nanoimprinting schemes

    NASA Astrophysics Data System (ADS)

    Park, Hyunsoo; Cheng, Xing

    2009-06-01

    Nanoimprinting is a fast-growing technique for nanoscale patterning. One of the remaining issues in nanoimprinting is the removal of the residual layer after nanoimprinting. Traditionally the residual layer is removed by an oxygen reactive-ion etching (RIE) step. The need for a vacuum environment and dedicated equipment in this step lowers the throughput and increases the cost of the nanoimprinting process. It also prevents the possibility of patterning isolated functional polymers because oxygen RIE destroys the functional materials. In this work, novel nanoimprinting schemes are developed to nondestructively remove the residual layer in thermal nanoimprinting by solvent developing and dewetting. Combined with a transfer-bonding technique, three-dimensional polymer scaffolds are achieved. The techniques developed here eliminate the RIE step in thermal nanoimprinting and are compatible with roller nanoimprinting for large-scale patterning of polymer micro- or nanostructures. The technique also opens up new applications for nanoimprinting in patterning isolated conjugated polymers for organic electronic devices and circuits.

  3. Thermoplastic polymer patterning without residual layer by advanced nanoimprinting schemes.

    PubMed

    Park, Hyunsoo; Cheng, Xing

    2009-06-17

    Nanoimprinting is a fast-growing technique for nanoscale patterning. One of the remaining issues in nanoimprinting is the removal of the residual layer after nanoimprinting. Traditionally the residual layer is removed by an oxygen reactive-ion etching (RIE) step. The need for a vacuum environment and dedicated equipment in this step lowers the throughput and increases the cost of the nanoimprinting process. It also prevents the possibility of patterning isolated functional polymers because oxygen RIE destroys the functional materials. In this work, novel nanoimprinting schemes are developed to nondestructively remove the residual layer in thermal nanoimprinting by solvent developing and dewetting. Combined with a transfer-bonding technique, three-dimensional polymer scaffolds are achieved. The techniques developed here eliminate the RIE step in thermal nanoimprinting and are compatible with roller nanoimprinting for large-scale patterning of polymer micro- or nanostructures. The technique also opens up new applications for nanoimprinting in patterning isolated conjugated polymers for organic electronic devices and circuits. PMID:19468173

  4. Photocleavable junctions in complex polymer architectures and photoetchable thermoplastics

    NASA Astrophysics Data System (ADS)

    Sterner, Elizabeth Surles

    Polymer materials have become important tools in nanomanufacturing due to their facile processing and ready attainment of the necessary feature sizes. The development of cleavable junctions has led to advances in the production of polymer nanotemplates. Photocleavage strategies have come to the forefront of the field because photons, as a cleavage stimulus, do not have the mass-transport limitations of chemical methods, and provide for targeted two- and three-dimensional feature control. This dissertation presents a method for producing photocleavable materials by one-pot copper-catalyzed azide-alkyne "click" chemistry (CuAAC), activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and activated ester substitution methods that have each block labeled with a fluorescent dye, enabling exploration of the polymer physics of these systems by correlation fluorescence spectroscopy. It also introduces a novel photocleavable linker, the o-nitrobenzyl-1,2,3-triazole, its behavior on photocleavage, and a facile method for the production of the o-nitrobenzyl azides necessary for their synthesis. The synthesis and properties of a bulk photodegradable polytriazole are reported, as are proof of concept experiments demonstrating its potential as a directly photoetchable material. Lastly, this dissertation contains a perspective on possible avenues of new research on the topics presented.

  5. Biomedical application of commercial polymers and novel polyisobutylene-based thermoplastic elastomers for soft tissue replacement.

    PubMed

    Puskas, Judit E; Chen, Yaohong

    2004-01-01

    Novel polyisobutylene-based thermoplastic elastomers are introduced as prospective implant materials for soft tissue replacement and reconstruction. In comparison, poly(ethylene terephthalate) (PET), poly(tetrafluoroethylene) (PTFE), polypropylene (PP), polyurethanes (PU), and silicones are outlined from well-established implant history as being relatively inert and biocompatible biomaterials for soft tissue replacement, especially in vascular grafts and breast implants. Some general considerations for the design and development of polymers for soft tissue replacement are reviewed from the viewpoint of material science and engineering, with special attention to synthetic materials used in vascular grafts and breast implants. PMID:15244424

  6. Adhesion between thermoplastic polymer particles and carbon and glass fibers

    SciTech Connect

    Colton, J.S.

    1996-12-31

    High performance composites consist of polymer matrices reinforced with continuous fibers. Polymer powders can be coated and fused onto the fibers by various techniques to produce these composites. One such technique consists of spreading the fibers with an air banding jet, and then running the fibers through a fluidized bed of the powder. The fluidizing air is typically charged, imparting a charge to the powder particles. The fibers are grounded which leads to an attraction between the particles and the fibers. The particle-coated fibers then go through a tunnel oven, sintering the particles onto the fibers, leaving a flexible {open_quotes}tow-preg{close_quotes} which can then be processed into a preform for manufacture into a final part. To develop an initial understanding of the powder coating process, the adhesion of uncharged particles and fibers was studied. Contact mechanics predicts that the adhesion force between uncharged particles depends on the mutual (or equivalent) radius of curvature between the contacting objects, as well as their surface energies. For the materials of interest, the Derjaguin approximation is appropriate and is applied. PEEK (poly ether ether ketone) and PET (poly ethylene terephthalate) particles, cryogenically ground to nominal diameters of 10 to 100 {mu}m were brought into contact with themselves, with E-glass fibers (nominal diameter of 20 {mu}m), carbon fibers (nominal diameter of 8 {mu}m), and glass microscope slides using an AFM. Adhesion forces were measured and compared to predictions using Derjaguin`s approximation. SEM micrographs were used to determine the scale of the radii of curvature of contacting sites.

  7. 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.

  8. 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

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

    PubMed

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

    2006-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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


  11. 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. (Inventor)

    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.

  12. Remotely actuated polymer nanocomposites-stress-recovery of carbon-nanotube-filled thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Koerner, Hilmar; Price, Gary; Pearce, Nathan A.; Alexander, Max; Vaia, Richard A.

    2004-02-01

    Stimuli-responsive (active) materials undergo large-scale shape or property changes in response to an external stimulus such as stress, temperature, light or pH. Technological uses range from durable, shape-recovery eye-glass frames, to temperature-sensitive switches, to the generation of stress to induce mechanical motion. Here, we demonstrate that the uniform dispersion of 1-5 vol.% of carbon nanotubes in a thermoplastic elastomer yields nanocomposites that can store and subsequently release, through remote means, up to 50% more recovery stress than the pristine resin. The anisotropic nanotubes increase the rubbery modulus by a factor of 2 to 5 (for 1-5 vol.%) and improve shape fixity by enhancing strain-induced crystallization. Non-radiative decay of infrared photons absorbed by the nanotubes raises the internal temperature, melting strain-induced polymer crystallites (which act as physical crosslinks that secure the deformed shape) and remotely trigger the release of the stored strain energy. Comparable effects occur for electrically induced actuation associated with Joule heating of the matrix when a current is passed through the conductive percolative network of the nanotubes within the resin. This unique combination of properties, directly arising from the nanocomposite morphology, demonstrates new opportunities for the design and fabrication of stimuli-responsive polymers, which are otherwise not available in one material system.

  13. Study of double-side ultrasonic embossing for fabrication of microstructures on thermoplastic polymer substrates.

    PubMed

    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

  14. 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

  15. 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

  16. Thermal properties of thermoplastic starch/synthetic polymer blends with potential biomedical applicability.

    PubMed

    Mano, J F; Koniarova, D; Reis, R L

    2003-02-01

    Previous studies shown that thermoplastic blends of corn starch with some biodegradable synthetic polymers (poly(epsilon-caprolactone), cellulose acetate, poly(lactic acid) and ethylene-vinyl alcohol copolymer) have good potential to be used in a series of biomedical applications. In this work the thermal behavior of these structurally complex materials is investigated by differential scanning calorimetry (DSC) and by thermogravimetric analysis (TGA). In addition, Fourier-transform infrared (FTIR) spectroscopy was used to investigate the chemical interactions between the different components. The endothermic gelatinization process (or water evaporation) observed by DSC in starch is also observed in the blends. Special attention was paid to the structural relaxation that can occur in the blends with poly(lactic acid) at body temperature that may change the physical properties of the material during its application as a biomaterial. At least three degradation mechanisms were identified in the blends by means of using TGA, being assigned to the mass loss due to the plasticizer leaching, and to the degradation of the starch and the synthetic polymer fractions. The non-isothermal kinetics of the decomposition processes was analyzed using two different integral methods. The analysis included the calculation of the activation energy of the correspondent reactions. PMID:15348484

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

    PubMed

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

    2010-11-01

    Although biodegradable polymers have found extensive application in medical devices, there are very few commercially available elastomeric biodegradable polymers. In this work, starting with the well-known monomers L-lactide and ε-caprolactone, we developed elastomers using a multiblock co-polymer approach. This ensures that the degradation products of such elastomers are also acceptable from a cytotoxicity standpoint. A series of polymers with various structures was synthesized utilizing a design of experiment approach. The basic structure is that of a diblock, with each block being modified by the addition of co-monomer. The synthesized polymers exhibited a range of mechanical properties from a typical thermoplastic polymer to that approaching a good thermoplastic elastomer. 13C nuclear magnetic resonance analysis, size exclusion chromatography and differential scanning calorimetry measurements have been utilized to relate the observed range of mechanical properties to the structure. In addition, the elastomeric nature has been established with the use of creep and recovery measurements. Such elastomers may find a variety of biomedical applications, ranging from stent coatings to atrial septal defect occluders. PMID:20566308

  19. 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 μm to 200 μm 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 μm. 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.

  20. Towards tunable sensitivity of electrical property to strain for conductive polymer composites based on thermoplastic elastomer.

    PubMed

    Lin, Lin; Liu, Siyao; Zhang, Qi; Li, Xiaoyu; Ji, Mizhi; Deng, Hua; Fu, Qiang

    2013-06-26

    The use of conductive polymer composites (CPCs) as strain sensors has been widely investigated and various resistivity-strain sensitivities are desirable for different applications. In this study, the use of mixed carbon fillers and functionalized carbon nanotubes was demonstrated to be vital for preparing thermoplastic polyurethane (TPU)-based strain sensors with tunable sensitivity. To understand the strain sensing behavior, we carried out scanning electron microscopy (SEM), Raman spectroscopy, wide-angle X-ray diffraction (WAXD), mechanical test, and rheology-electrical measurement. Hybrid fillers of multi-walled carbon nanotubes (MWNTs) and carbon black (CB) could reduce the entanglement in conductive network structure, thus increase the resistivity-strain sensitivity. Furthermore, incorporation of additional functionalized MWNTs in the CPCs could enhance the interfacial interaction between nanofillers and TPU, leading to further increase in sensitivity. Through such a simple method, strain sensors could be efficiently fabricated with large strain-sensing capability (strain as large as 200%) and a wide range of strain sensitivity (gauge factor ranging from 5 to 140238). Finally, the exponential revolution of resistive response to strain was fitted with a model based on tunneling theory by Simmons. It was observed that the change in tunneling distance and the number of conductive pathways could be accelerated significantly by adjusting conductive network structure and interfacial interaction. This study provides a guideline for the preparation of high-performance CPC strain sensors with a large range of resistivity-strain sensitivity. PMID:23713404

  1. Filling of simulated lateral canals with gutta-percha or thermoplastic polymer by warm vertical compaction.

    PubMed

    Sant'Anna-Junior, Arnaldo; Guerreiro-Tanomaru, Juliane Maria; Martelo, Roberta Bosso; Silva, Guilherme Ferreira da; Tanomaru Filho, Mário

    2015-01-01

    The aim of this study was to evaluate the ability of gutta-percha and a thermoplastic synthetic polymer (Resilon) to fill simulated lateral canals, using warm vertical compaction. Forty-five single-rooted human teeth were prepared using the rotary crown-down technique. Artificial lateral canals were made at 2, 5, and 8 mm from the working length (WL) in each root. The specimens were divided into three groups (n = 15), according to the filling material: Dentsply gutta-percha (GD), Odous gutta-percha (GO), and Resilon cones (RE). The root canals were obturated using warm vertical compaction, without endodontic sealer. The specimens were subjected to a tooth decalcification and clearing procedure. Filling of the lateral canals was analyzed by digital radiography and digital photographs, using the Image Tool software. The data were subjected to the Kruskal-Wallis and Dunn tests at 5% significance. RE had the best filling ability in all root thirds (p < 0.05), with similar results for GO in the coronal third. In the middle and apical thirds, GD and GO had similar results (p > 0.05). Resilon may be used as an alternative to gutta-percha as a solid core filling material for use with the warm vertical compaction technique. The study findings point to the potential benefit of the warm vertical compaction technique for filling lateral canals, and the study provides further information about using Resilon and gutta-percha as materials for the warm vertical compaction technique. PMID:25885024

  2. Lignin-Based Thermoplastic Materials.

    PubMed

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

    2016-04-21

    Lignin-based thermoplastic materials have attracted increasing interest as sustainable, cost-effective, and biodegradable alternatives for petroleum-based thermoplastics. As an amorphous thermoplastic material, lignin has a relatively high glass-transition temperature and also undergoes radical-induced self-condensation at high temperatures, which limits its thermal processability. Additionally, lignin-based materials are usually brittle and exhibit poor mechanical properties. To improve the thermoplasticity and mechanical properties of technical lignin, polymers or plasticizers are usually integrated with lignin by blending or chemical modification. This Review attempts to cover the reported approaches towards the development of lignin-based thermoplastic materials on the basis of published information. Approaches reviewed include plasticization, blending with miscible polymers, and chemical modifications by esterification, etherification, polymer grafting, and copolymerization. Those lignin-based thermoplastic materials are expected to show applications as engineering plastics, polymeric foams, thermoplastic elastomers, and carbon-fiber precursors. PMID:27059111

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

    DOEpatents

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

    2014-06-10

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

  4. Engineering Polymer Blends for Impact Damage Mitigation

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L.; Smith, Russell W.; Working, Dennis C.; Siochi, Emilie J.

    2016-01-01

    Structures containing polymers such as DuPont's Surlyn® 8940, demonstrate puncture healing when impacted by a 9 millimeter projectile traveling from speeds near 300 meters per second (1,100 feet per second) to hypervelocity impacts in the micrometeoroid velocity range of 5 kilometers per second (16,000 feet per second). Surlyn® 8940 puncture heals over a temperature range of minus 30 degrees Centigrade to plus 70 degrees Centigrade and shows potential for use in pressurized vessels subject to impact damage. However, such polymers are difficult to process and limited in applicability due to their low thermal stability, poor chemical resistance and overall poor mechanical properties. In this work, several puncture healing engineered melt formulations were developed. Moldings of melt blend formulations were impacted with a 5.56 millimeter projectile with a nominal velocity of 945 meters per second (3,100 feet per second) at about 25 degrees Centigrade, 50 degrees Centigrade and 100 degrees Centigrade, depending upon the specific blend being investigated. Self-healing tendencies were determined using surface vacuum pressure tests and tensile tests after penetration using tensile dog-bone specimens (ASTM D 638-10). For the characterization of tensile properties both pristine and impacted specimens were tested to obtain tensile modulus, yield stress and tensile strength, where possible. Experimental results demonstrate a range of new puncture healing blends which mitigate damage in the ballistic velocity regime.

  5. Modeling and Simulation of the Flow of a Thermoplastic Polymer during Filling of a Cylindrical Micro-Cavity

    NASA Astrophysics Data System (ADS)

    Sahli, M.; Gelin, J. C.; Malek, C. Khan; Roques-Carmes, C.

    2007-05-01

    This work is related to experiments and modelling concerning viscous polymer flow such as cyclo-olefin polymer (COP) and cyco-olefin copolymer (COC) arising in the hot embossing process in order to understand and predict the filling of microcavities. The simulation results are obtained for axisymmetric geometries. The filling time and the dimensions of polymer with the rheological and experimental process parameters are obtained. From the variations of the radius characterizing the squeeze flow of the polymers between plates with or without cavities, it is possible to relate the rheological properties (fluidity index, consistency, melt flow index and viscosity) to the aptitude of the polymers to reproduce the geometrical shape and surface asperities of a microstructured mould. The flow imposed to the polymeric material in shear or elongational mode was correlated to the rheological approach. This approach allows to better understand the compression of thermoplastic disks as well as the filling mechanism of cylindrical cavities while providing a predictive approach for the of embossing pressure during the process.

  6. Novel polymer electrolytes based on thermoplastic polyurethane and ionic liquid/lithium bis(trifluoromethanesulfonyl)imide/propylene carbonate salt system

    NASA Astrophysics Data System (ADS)

    Lavall, R. L.; Ferrari, S.; Tomasi, C.; Marzantowicz, M.; Quartarone, E.; Magistris, A.; Mustarelli, P.; Lazzaroni, S.; Fagnoni, M.

    Polymer electrolytes were prepared from thermoplastic polyurethane with addition of mixture of ionic liquid N-ethyl(methylether)-N-methylpyrrolidinium trifluoromethanesulfonimmide (PYRA 12O1TFSI), lithium bis(trifluoromethanesulfoneimide) salt and propylene carbonate. The electrolytes characterization was performed by thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy. The electrical properties were investigated in detail by impedance spectroscopy with the aid of equivalent circuit fitting of the impedance spectra. A model describing temperature evolution of ionic conductivity and the properties of electrolyte/blocking electrode interface was developed. The electrochemical stability of the electrolytes was studied by linear voltammetry. Our results indicate that the studied electrolytes have good self-standing characteristics, and also a sufficient level of thermal stability and a fairly good electrochemical window. The ionic conductivity increases with increasing amount of mixture, and the character of temperature dependence of conductivity indicates decoupling of ion transport from polymer matrix. For studied system, the highest value of ionic conductivity measured at room temperature was 10 -4 S cm -1.

  7. Comparison of glow argon plasma-induced surface changes of thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Řezníčková, A.; Kolská, Z.; Hnatowicz, V.; Stopka, P.; Švorčík, V.

    2011-01-01

    Modification of high-density polyethylene (PE), polytetrafluoroethylene (PTFE), polystyrene (PS), polyethyleneterephthalate (PET) and polypropylene (PP) by Ar plasma was studied. The amount of the ablated material was determined by gravimetry. Wettability of polymers after the plasma treatment was determined from the contact angle measurement. The changes in the surface morphology of polymers were observed using atomic force microscopy (AFM). Chemical structure of modified polymers was characterized by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Surface changes were also studied by the determination of electrokinetic potential ( ζ-potential). It was found that under the plasma treatment the polymers are ablated and their surface morphology and roughness are changed dramatically. XPS measurements indicate an oxidation of the polymer surface. The plasma treatment results in a dramatic increase of the ζ-potential. EPR data show different radical amount present on the treated surface of all polymers. Most significant changes due to the degradation of polymer chains are observed on PTFE.

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

    PubMed

    Li, Hongze; Gao, Xiang; Luo, Yingwu

    2016-04-01

    Multi-shape memory polymers were prepared by the macroscale spatio-assembly of building blocks in this work. The building blocks were methyl acrylate-co-styrene (MA-co-St) copolymers, which have the St-block-(St-random-MA)-block-St tri-block chain sequence. This design ensures that their transition temperatures can be adjusted over a wide range by varying the composition of the middle block. The two St blocks at the chain ends can generate a crosslink network in the final device to achieve strong bonding force between building blocks and the shape memory capacity. Due to their thermoplastic properties, 3D printing was employed for the spatio-assembly to build devices. This method is capable of introducing many transition phases into one device and preparing complicated shapes via 3D printing. The device can perform a complex action via a series of shape changes. Besides, this method can avoid the difficult programing of a series of temporary shapes. The control of intermediate temporary shapes was realized via programing the shapes and locations of building blocks in the final device. PMID:26924759

  9. 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 (μpart) 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 μpart 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.

  10. A Process for Semi-Solid Moulding of High Viscosity Thermoplastic Polymers

    NASA Astrophysics Data System (ADS)

    Frick, Achim; Rochman, Arif; Martin, Peter

    2011-05-01

    A new moulding process for manufacturing micro parts made from high viscosity polymers has been developed as a result of a feasibility study. The process basically involves compression moulding of a polymeric preform by heating it up to its semi-solid state, i.e. between its glass transition temperature and melting temperature. The apparatus is made up of three main parts: a forming device, a single cavity micro mould and an induction heating system. The processing technique was successfully tested in the manufacturing of 10 mm round discs with a flange and inner bore using high viscosity polymers such as polyphenylene sulfide (PPS), polyetheretherketone (PEEK), ultra-high molecular weight polyethylene (UHMW PE) and polytetrafluoroethylene (PTFE). In a further miniaturization study, U-shaped micro seals with an outer diameter up to 2.5 mm were also successfully manufactured from non-injection mouldable PTFE. Thus, the new process is a realistic alternative technique to the existing micro moulding processes with respect to its capability to process a huge variety of polymers, even ultra high viscosity materials and the possibility to create micro parts with non-uniform wall thickness distributions.

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

    PubMed

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

    2016-01-01

    Hard biological polymers exhibiting a truly thermoplastic behavior that can maintain their structural properties after processing are extremely rare and highly desirable for use in advanced technological applications such as 3D-printing, biodegradable plastics and robust composites. One exception are the thermoplastic proteins that comprise the sucker ring teeth (SRT) of the Humboldt jumbo squid (Dosidicus gigas). In this work, we explore the mechanical properties of reconstituted SRT proteins and demonstrate that the material can be re-shaped by simple processing in water and at relatively low temperature (below 100 °C). The post-processed material maintains a high modulus in the GPa range, both in the dry and the wet states. When transitioning from low to high humidity, the material properties change from brittle to ductile with an increase in plastic deformation, where water acts as a plasticizer. Using synchrotron x-ray scattering tools, we found that water mostly influences nano scale structure, whereas at the molecular level, the protein structure remains largely unaffected. Furthermore, through simultaneous in situ x-ray scattering and mechanical tests, we show that the supramolecular network of the reconstituted SRT material exhibits a progressive alignment along the strain direction, which is attributed to chain alignment of the amorphous domains of SRT proteins. The high modulus in both dry and wet states, combined with their efficient thermal processing characteristics, make the SRT proteins promising substitutes for applications traditionally reserved for petroleum-based thermoplastics. PMID:27588938

  12. Novel elastomers, characterization techniques, and improvements in the mechanical properties of some thermoplastic biodegradable polymers and their nanocomposites

    NASA Astrophysics Data System (ADS)

    Hassan, Mohamed Korany Ibrahim

    This work focused in its first part on the preparation and characterization of novel elastomers based on poly(tetrahydrofuran) (PTHF) networks. Elastomers were prepared by a hydrolysis-condensation reaction which has been followed up by FTIR spectroscopic techniques. The elastomers thus obtained were studied with regard to their equilibrium swelling in toluene at 25°C, and their stress-strain isotherms in elongation. For some of the samples, high elongations seemed to bring about highly desirable strain-induced crystallization, as evidenced by upturns in the modulus. Swelling of these samples with increasing amounts of the non-volatile diluent dibutyl phthalate caused the upturns to gradually disappear. The second part of this work was focused on diversifying the newly developed sound wave propagation technique to characterize elastomeric polymer networks. The technique was applied to characterize polybutadiene (PBD) networks. The speed of wave propagation in PBD networks was found to be strongly dependent on the network structural parameters such as average molecular weight of chain between crosslinks and entanglement molecular weight. Also, for the swollen networks, pulse speeds decreased with increase in degree of swelling. Upturns due to strain-induced crystallization at higher elongations were clearly evidenced in the pulse speeds. The third part of this work presented improvements in the mechanical properties of thermoplastic biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (Nodax(TM)) using a pre-orientation technique. This simple approach involved heating the polymer film to a temperature above its glass transition temperature, stretching it to the desired extension (%), and then quenching it to room temperature while in the stretched state. As expected, pre-orientation resulted in substantial improvements in the mechanical properties of the films. The pre-oriented films had higher values of the modulus, toughness, yield stress, and tensile

  13. A method for the accelerated simulation of micro-embossed topographies in thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Taylor, Hayden; Hale, Melinda; Cheong Lam, Yee; Boning, Duane

    2010-06-01

    Users of hot micro-embossing often wish to simulate numerically the topographies produced by the process. We have previously demonstrated a fast simulation technique that encapsulates the embossed layer's viscoelastic properties using the response of its surface topography to a mechanical impulse applied at a single location. The simulated topography is the convolution of this impulse response with an iteratively found stamp-polymer contact-pressure distribution. Here, we show how the simulation speed can be radically increased by abstracting feature-rich embossing-stamp designs. The stamp is divided into a grid of regions, each characterized by feature shape, pitch and areal density. The simulation finds a contact-pressure distribution at the resolution of the grid, from which the completeness of pattern replication is predicted. For a 25 mm square device design containing microfluidic features down to 5 µm diameter, simulation can be completed within 10 s, as opposed to the 104 s expected if each stamp feature were represented individually. We verify the accuracy of our simulation procedure by comparison with embossing experiments. We also describe a way of abstracting designs at multiple levels of spatial resolution, further accelerating the simulation of patterns whose detail is contained in a small proportion of their area.

  14. 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.

  15. Derivation of heating rate dependent exposure strategies for the selective laser melting of thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Drummer, Dietmar; Drexler, Maximilian; Wudy, Katrin

    2015-05-01

    The selective laser melting of polymer powder is for rapid prototyping applications an established technology, although a lack in basic process knowledge appears. Considering demands of series production the selective laser melting technique is faced with varies challenges concerning processable material systems, process strategies and part properties. Consequently basic research is necessary to shift from rapid prototyping to rapid manufacturing of small lot sized series. Based on basic research the high potential of selective laser melting for the production of complex parts without any tools can be opened up. For the derivation of part quality increasing process strategies knowledge about interactions between sub-processes of selective laser melting and resulting part properties is necessary. The selective laser melting consists of three major sub-processes: Geometry exposure, tempering and powder feeding. According to the interaction of sub-processes resulting temperature fields during the selective laser melting process determine the part properties by changing micro structural pore number and distribution. Beneath absolute temperatures also the time-dependency of the thermal fields influences the porosity of molten parts. Present process strategies tend to decrease building time by increasing scanning speed and laser power. Although the absolute energy input into the material is constant for increasing scanning speed and laser power in the same ratio, time dependent material effects are neglected. The heating rate is a combined parameter derived from absolute temperature and time. Within the paper the authors analyze the basic interactions between different heating rates and part properties (e.g. porosity, mechanical strengths). Therefore with different heating rates produced specimens are analyzed with imaging technologies as well as mechanical tests. Based on the done basic investigations new heating rate dependent process strategies can be established

  16. 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.

  17. An overview of long fiber reinforced thermoplastics

    SciTech Connect

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

    1995-12-01

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

  18. 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...

  19. A wide characterization of paraffin-based fuels mixed with styrene-based thermoplastic polymers for hybrid propulsion

    NASA Astrophysics Data System (ADS)

    Boiocchi, M.; Milova, P.; Galfetti, L.; Di Landro, L.; Golovko, A. K.

    2016-07-01

    In the framework of a long-term research activity focused on the development of high-performance solid fuels for hybrid rockets, paraffin-based fuels were investigated and characterized using two different pure paraffinic waxes and a styrene-based thermoplastic elastomer as strengthening material. The fuels were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis / differential thermal analysis (TGA-DTA). The viscosity of the melt layer, responsible for the entrainment effect, was investigated using a Couette viscosimeter. The storage modulus (G') was analyzed using a parallel-plate rheometer. The chemical composition of the pure paraffinic materials was studied using gas chromatography / mass spectrometry (GC-MS), while mechanical properties were investigated through uniaxial tensile tests.

  20. Investigations of the surface activation of thermoplastic polymers by atmospheric pressure plasma treatment with a stationary plasma jet

    NASA Astrophysics Data System (ADS)

    Moritzer, Elmar; Nordmeyer, Timo; Leister, Christian; Schmidt, Martin Andreas; Grishin, Artur; Knospe, Alexander

    2016-03-01

    The production of high-quality thermoplastic parts often requires an additional process step after the injection molding stage. This may be a coating, bonding process or a 2K-injection moulding process. A commonly used process to improve the bond strength is atmospheric pressure plasma treatment. A variety of applications are realized with the aid of CNC systems. Although they ensure excellent reproducibility, they make it difficult to implement inline applications. This paper therefore examines the possibility of surface treatment using a stationary plasma jet. However, before it is possible to integrate this technology into a production process, preliminary trials need to be carried out to establish which factors influence the process. Experimental tests were performed using a special test set-up, enabling geometric, plasma-specific parameters to be identified. These results can help with the practical integration of this technology into existing production processes.

  1. Drying Thermoplastics

    NASA Technical Reports Server (NTRS)

    1976-01-01

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

  2. 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.

  3. 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

  4. 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.

  5. Three-dimensional bioprinting of cell-laden constructs with polycaprolactone protective layers for using various thermoplastic polymers.

    PubMed

    Kim, Byoung Soo; Jang, Jinah; Chae, Suhun; Gao, Ge; Kong, Jeong-Sik; Ahn, Minjun; Cho, Dong-Woo

    2016-01-01

    Three-dimensional (3D) cell-printed constructs have been recognized as promising biological substitutes for tissue/organ regeneration. They provide tailored physical properties and biological cues via multi-material printing process. In particular, hybrid bioprinting, enabling to use biodegradable synthetic polymers as framework, has been an attractive method to support weak hydrogels. The constructs with controlled architecture and high shape fidelity were fabricated through this method, depositing spatial arrangement of multi-cell types into microscale constructs. Among biodegradable synthetic polymers, polycaprolactone (PCL) has been commonly chosen in fabrication of cell-printed constructs because of its low melting temperature of 60 °C to be dispensed with extrusion-based bioprinting system. However, in addition to PCL, various synthetic polymers have been widely applied for tissue regeneration. These polymers have distinctive characteristics essential for tissue/organ regeneration. Nevertheless, it is difficult to use some polymers, such as poly (lactic-co-glycolic acid) (PLGA) and polylactic acid (PLA) with 3D bioprinting technology because of their high melting temperature to be dispensed, which can result in thermal damage to the cells in the printed constructs during the fabrication process. We present a novel bioprinting method to use various synthetic polymers in fabrication of cell-printed constructs. PCL was introduced as a protective layer to prevent thermal damage caused by high temperature of polymers during fabrication. Remarkable improvement in cellular activities in the printed constructs with PCL layers was observed compared with the construct without PCL. This bioprinting method can be applied to fabricate more tissue-like constructs through the use of various biomaterials. PMID:27550946

  6. Fabrication and characterization of a foamed polylactic acid (PLA)/ thermoplastic polyurethane (TPU) shape memory polymer (SMP) blend for biomedical and clinical applications

    NASA Astrophysics Data System (ADS)

    Song, Janice J.; Srivastava, Ijya; Kowalski, Jennifer; Naguib, Hani E.

    2014-03-01

    Shape memory polymers (SMP) are a class of stimuli-responsive materials that are able to respond to external stimulus such as heat by altering their shape. Bio-compatible SMPs have a number of advantages over static materials and are being studied extensively for biomedical and clinical applications (such as tissue stents and scaffolds). A previous study has demonstrated that the bio-compatible polymer blend of polylactic acid (PLA)/ thermoplastic polyurethane (TPU) (50/50 and 70/30) exhibit good shape memory properties. In this study, the mechanical and thermo-mechanical (shape memory) properties of TPU/PLA SMP blends were characterized; the compositions studied were 80/20, 65/35, and 50/50 TPU/PLA. In addition, porous TPU/PLA SMP blends were fabricated with a gas-foaming technique; and the morphology of the porous structure of these SMPs foams were characterized with scanning electron microscopy (SEM). The TPU/PLA bio-compatible SMP blend was fabricated with melt-blending and compression molding. The glass transition temperature (Tg) of the SMP blends was determined with a differential scanning calorimeter (DSC). The mechanical properties studied were the stress-strain behavior, tensile strength, and elastic modulus; and the thermomechanical (or shape memory) properties studied were the shape fixity rate (Rf), shape recovery rate (Rr), response time, and the effect of recovery temperature on Rr. The porous 80/20 PLA/TPU SMP blend was found to have the highest tensile strength, toughness and percentage extension, as well as the lowest density and uniform pore structure in the micron and submicron scale. The porous 80/20 TPU/PLA SMP blend may be further developed for specific biomedical and clinical applications where a combination of tensile strength, toughness, and low density are required.

  7. Electrostatic prepregging of thermoplastic matrices

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  8. Thermoplastic elastomers in medical applications.

    PubMed

    Radley, Huw

    2003-05-01

    TPEs provide medical designers with a broad spectrum of soft-feel, hygienic materials that can readily fulfill accepted medical industry standards with the exception of body implants. Ultimate performance is a combination of tailor-made formulations coupled with innovative design that captures the capability of the material's properties and thermoplastic processing techniques, including combination with other polymers by coinjection moulding or coextrusion. PMID:12774579

  9. 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.

  10. Nanocellular thermoplastic foam and process for making the same

    SciTech Connect

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

    2015-09-29

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

  11. Effect of annealing history on free volume in thermoplastics

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  12. Feasibility of bloodless liver resection using Lumagel, a reverse thermoplastic polymer, to produce temporary, targeted hepatic blood flow interruption

    PubMed Central

    Pomposelli, James J; Akoad, Mohamed; Flacke, Sebastian; Benn, James J; Solano, Mauricio; Kalra, Aarti; Madras, Peter N

    2012-01-01

    Background Lumagel, a reverse thermosensitive polymer (RTP), provides targeted flow interruption to the kidney by reversibly plugging segmental branches of the renal artery, allowing blood-free partial nephrectomy. Extending this technology to the liver requires the development of techniques for temporary occlusion of the hepatic artery and selected portal vein branches. Methods A three-phased, 15 swine study was performed to determine feasibility, techniques and survival implications of using Lumagel for occlusion of inflow vessels to targeted portions of the liver. Lumagel was delivered using angiographic techniques to sites determined by pre-operative 3-D vascular reconstructions of arterial and venous branches. During resection, the targeted liver mass was resected without vascular clamping. Three survival swine were sacrificed at 3 weeks; the remainder at 6 weeks for pathological studies. Results Six animals (100%) survived, with normal growth, blood tests and no adverse events. Three left lateral lobe resections encountered no bleeding during resection; one right median resection bled; two control animals bled significantly. Pre-terminal angiography and autopsy showed no local pathology and no remote organ damage. Conclusions Targeted flow interruption to the left lateral lobe of the swine liver is feasible and allows resection without bleeding, toxicity or pathological sequelae. Targeting the remaining liver will require more elaborate plug deposition owing to the extensive collateral venous network. PMID:22221572

  13. 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.

  14. Thermoplastic composites for ballistic application

    NASA Astrophysics Data System (ADS)

    Song, John Whachong

    2003-08-01

    Systematic studies of thermoplastic composites on ballistic impact failure and kinetic energy absorption mechanisms were examined on both semicrystalline and amorphous polymer matrix composites. By taking advantages of the nature of thermoplastic polymers, the main objective of this research was to develop armor grade composites with thermoplastic resin matrices through a understanding of the microscopic as well as macroscopic characteristics of the composites. In both semicrystalline neat resin and composites, the crystal formation and the degree of crystallinity of the polymer matrix were greatly influenced by processing conditions, especially, the cooling rate. As the cooling rate is decreased, more perfect crystal formation and amorphous rearrangements were evident vs cooling at higher rates. The relative degree of crystallinity of semicrystalline matrix composites was calculated using dynamic mechanical analysis (DMA). These values were in good agreement with neat resin values obtained via differantial scanning calorimeter (DSC). Unfortunately, the morphological perfection of the semicrystalline matrix exhibits negligible advantage on ballistic impact resistance. Failure of the composites under ballistic impact was localized and the kinetic energy absorption was low. Amorphous polymers were also greatly influenced by processing conditions. Furthermore, amorphous polymers exhibit large processing windows in terms of processing temperature, which allows the various processing manipulations for ballistic composite fabrication. As increasing processing temperature, glass transition temperature of the polymer and stiffness of the composite increased due to the morphological perfection and level of wetting, respectively. Ballistic impact resistance was found to be inversely proportional to the stiffness of the composites. Fiber wetting characteristics and polymer morphology changes during the cooling process are considered to be major contributors of this behavior

  15. 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.

  16. Recent Developments on Thermoplastic Elastomers by Dynamic Vulcanization

    NASA Astrophysics Data System (ADS)

    Babu, R. Rajesh; Naskar, Kinsuk

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  19. 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.

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

    PubMed

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

    2010-03-01

    This paper presents the synthesis and characterization of a polyisobutylene (PIB)-based nanostructured carbon-reinforced thermoplastic elastomer. This thermoplastic elastomer is based on a self-assembling block copolymer having a branched PIB core carrying -OH functional groups at each branch point, flanked by blocks of poly(isobutylene-co-para-methylstyrene). The block copolymer has thermolabile physical crosslinks and can be processed as a plastic, yet retains its rubbery properties at room temperature. The carbon-reinforced thermoplastic elastomer had more than twice the tensile strength of the neat polymer, exceeding the strength of medical grade silicone rubber, while remaining significantly softer. The carbon-reinforced thermoplastic elastomer displayed a high T(g) of 126 degrees C, rendering the material steam-sterilizable. The carbon also acted as a free radical trap, increasing the onset temperature of thermal decomposition in the neat polymer from 256.6 degrees C to 327.7 degrees C. The carbon-reinforced thermoplastic elastomer had the lowest water contact angle at 82 degrees and surface nano-topography. After 180 days of implantation into rabbit soft tissues, the carbon-reinforced thermoplastic elastomer had the thinnest tissue capsule around the microdumbbell specimens, with no eosinophiles present. The material also showed excellent integration into bones. PMID:20034664

  1. Making Thermoplastics Flame-Resistant

    NASA Technical Reports Server (NTRS)

    Mueller, W. A.; Ingham, J. D.; Reilly, W. W.

    1984-01-01

    Inorganic hydrate-salt filler coated with elastomer containing acidic groups imparts flame and smoke retardancy to thermoplastics while preventing degradation of impact resistance that results from high filler loadings in thermoplastic.

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

    PubMed Central

    Rahmanian, Omid

    2013-01-01

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

  3. LARC-I-TPI: A New Thermoplastic Polyimide

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Progar, Donald J.; Pratt, J. Richard

    1990-01-01

    "LARC-I-TPI" denotes improved version of LARC-TPI class of thermoplastic polyimides: high-performance polymers developed for manufacture of strong, lightweight aircraft structures. Melt-flow and adhesive properties of new polymers make them attractive for use as matrix resins for composites, molding powders, adhesives, and coating films. Less toxic, improved LARC-I-TPI polymers formulated without 3, 3'-diaminobenzophenone, which is mutagenic and commercially unavailable.

  4. 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.

  5. Welds in thermoplastic composite materials

    NASA Astrophysics Data System (ADS)

    Taylor, N. S.

    Welding methods are reviewed that can be effectively used for joining of thermoplastic composites and continuous-fiber thermoplastics. Attention is given to the use of ultrasonic, vibration, hot-plate, resistance, and induction welding techniques. The welding techniques are shown to provide complementary weld qualities for the range of thermoplastic materials that are of interest to industrial and technological applications.

  6. Hierarchically UVO patterned elastomeric and thermoplastic structures

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  7. 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%) ...

  8. A 69 cent look at thermoplastic softening

    NASA Technical Reports Server (NTRS)

    Vanasupa, Linda S.

    1993-01-01

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

  9. Carbon fiber reinforced thermoplastic composites for future automotive applications

    NASA Astrophysics Data System (ADS)

    Friedrich, K.

    2016-05-01

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

  10. Absorption depth profile of water on thermoplastic starch films

    SciTech Connect

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

    2000-01-01

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

  11. 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.

  12. 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.

  13. A critical mass flux model for the flammability of thermoplastics

    NASA Astrophysics Data System (ADS)

    Staggs, J. E. J.; Nelson, M. I.

    2001-09-01

    The combustion of thermoplastics is modelled using a critical mass flux hypothesis as the ignition and extinction criteria. Polymer degradation is modelled as a single-step first-order Arrhenius reaction term. A simple model for mass transport of polymer through the sample during pyrolysis is included. The degradation products are assumed to move out of the polymer instantaneously. The model consists of a nonlinear integral-differential advection-diffusion equation for the temperature in the thermoplastic, coupled to an ordinary differential equation, for the regression rate. Results are presented which quantify the effect that the thickness of the test sample has on the mass-loss rate, or equivalently heat-release rate, curve. From these we conclude that thermally thick samples are characterized by a region of steady burning which is independent of the initial sample thickness. The test method that we have in mind is the cone calorimeter.

  14. THERMOPLASTIC WAVES IN MAGNETARS

    SciTech Connect

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

    2014-10-20

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

  15. 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.

  16. 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.

  17. The effect of electron irradiation on the structure and the optical properties of silver particulate films deposited on modified thermoplastic polymer substrates

    NASA Astrophysics Data System (ADS)

    Kakkrannaya, A. Rakesha; Rao, K. Mohan; Tolpadi, Amita; Sanjeev, Ganesh; Pattabi, Manjunatha

    2016-03-01

    The silver (Ag) particulate films are prepared by the vacuum evaporation onto polystyrene (PS) substrates modified with 3-mercaptopropyltrimethoxysilane (MPTMS), pre-irradiated with the 8-MeV electron beam, held at a temperature 453 K. The effect of organosilane and electron irradiation dose on the Ag particulate structure is studied through optical spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED) pattern, atomic-force microscopy (AFM), and X-ray diffraction (XRD). The flat spectrum observed for the lower irradiation doses may be due to the formation of the clusters of different sizes and shapes. The band shift toward the higher wavelength is attributed to the increased aggregation leading to the formation of the larger-sized nanoclusters. A long tail extending to the higher wavelength region is also observed due to aggregation process. The FESEM studies indicate the formation of the silver nanoclusters. The decrease in the particle size with the increase in irradiation dose as seen through TEM studies is interpreted on the basis of polymer-metal particle interaction caused by the free radicals formed due to the electron irradiation of the MPTMS-modified PS substrates. The SAED pattern shows the crystalline nature of the silver particles formed on the pure PS and the MPTMS-modified PS substrates irradiated with the electron beam. The AFM studies show an increase in the average surface roughness of the silver films with the electron irradiation dose and the MPTMS concentration. XRD indicated the polycrystalline nature of silver film on the pre-irradiated PS substrates and formation of nanocrystallites of silver with preferred orientation on the MPTMS-modified PS substrates pre-irradiated with electron beam.

  18. Injection molding of thermoplastic elastomers for microstructured substrates

    NASA Astrophysics Data System (ADS)

    Birkar, Smita

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

  19. Graphite/Thermoplastic-Pultrusion Die

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. A review of recent developments in joining high-performance thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Cole, K. C.

    1991-06-01

    There is currently a great deal of interest in the use of thermoplastic polymers as matrices in fiber reinforced composites for high performance applications, such as those encountered in the aerospace industry. These materials include polyether ether ketone (PEEK), polyphenylene sulphide (PPS), polyetherimide (PEI), polyamideimide (PAI), polyamides, polyimides, and polysulphones. A literature review is provided on the different ways of joining high performance thermoplastic composites by adhesive and fusion bonding. The discussion on adhesive bonding includes examination of the performance of specific adhesive/thermoplastic combinations and of techniques for the preparation of composite surfaces: abrasion, etching, flame, and plasma treatments. Thermoplastic composite welding techniques discussed in depth include the following: heated press welding, resistance welding, induction welding, and ultrasonic welding. Works which examine or compare applications for these bonding techniques are also reviewed.

  5. 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.

  6. Thermoplastic tape compaction device

    DOEpatents

    Campbell, Vincent W.

    1994-01-01

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

  7. Applicability of thermoplastic composites for space structures

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.; Kushner, M.

    1978-01-01

    The discussion defines a thermoplastic resin and compares the structural and environmental properties and the fabrication and repairability of the thermoplastic composite with a typical epoxy composite. Low labor costs exhibited by the thermoplastic composites make them a priority consideration for use in space structure.

  8. 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.

  9. 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)

  10. Self-Healing Composite of Thermoset Polymer and Programmed Super Contraction Fibers

    NASA Technical Reports Server (NTRS)

    Li, Guoqiang (Inventor); Meng, Harper (Inventor)

    2016-01-01

    A composition comprising thermoset polymer, shape memory polymer to facilitate macro scale damage closure, and a thermoplastic polymer for molecular scale healing is disclosed; the composition has the ability to resolve structural defects by a bio-mimetic close-then heal process. In use, the shape memory polymer serves to bring surfaces of a structural defect into approximation, whereafter use of the thermoplastic polymer for molecular scale healing allowed for movement of the thermoplastic polymer into the defect and thus obtain molecular scale healing. The thermoplastic can be fibers, particles or spheres which are used by heating to a level at or above the thermoplastic's melting point, then cooling of the composition below the melting temperature of the thermoplastic. Compositions of the invention have the ability to not only close macroscopic defects, but also to do so repeatedly even if another wound/damage occurs in a previously healed/repaired area.

  11. Structure and thermoplasticity of coal

    SciTech Connect

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

    2004-07-01

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

  12. 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.

  13. 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.

  14. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

  15. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the products classified under SIC 28213 thermoplastic resins including those resins and resin groups... Butyrates Cellulose Acetate Resin *Cellulose Acetates *Cellulose Acetates Propionates Cellulose Nitrate... Polymers Nylon 11 Resin *Nylon 6-66 Copolymers *Nylon 6—Nylon 11 Blends Nylon 6 Resin Nylon 612 Resin...

  19. Synthesis and characterization of thermoplastic polyphenoxyquinoxalines

    NASA Astrophysics Data System (ADS)

    Erdem, Haci Bayram

    This research was divided into two main parts. In the first part, a new facile route to relatively inexpensive thermoplastic polyphenoxyquinoxalines was developed. The synthetic route involves the aromatic nucleophilic substitution reaction of bisphenols with 2,3-dichloroquinoxaline. The dichloro monomer was prepared in two steps. In the first step, oxalic acid was condensed with o-phenylenediamine to give 2,3-dihydroxyquinoxaline. In the second step, 2,3-dihydroxyquinoxaline was treated with thionyl chloride to give 2,3-dichloroquinoxaline. This monomer was successfully polymerized with bisphenol-A, bisphenol-S, hexafluorobisphenol-A and 9,9-bis(4-hydroxyphenyl)fluorenone. Hydroquinone and biphenol, however, can not be polymerized to high molecular weight polymers because of the premature precipitation of crystalline oligomers. The glass transition temperatures of the high molecular weight polymers prepared from a series of bisphenols range from 191 °C to 279 °C, and their thermal decomposition temperatures are around 500 °C. The polymers are soluble in a wide range of solvents and can be solution-cast into thin films that are colorless and transparent. The polymers have tensile strengths ranging from 61 to 107 MPa, and tensile moduli ranging from 3.5 to 2.3 GPa. The synthesis of polymer obtained from 2,3-dichloroquinoxaline and bisphenol-A was scaled up to afford 500 g of material. This polymer is a thermoplastic with a melt-viscosity less than 1000 Pa.s. at 300 °C. The notched Izod impact strength of injection-molded samples of this polymer is 40.7 J/m. In the second part of this research, the synthetic method has been modified to allow the preparation of quinoxaline containing polyimides. Thus, 2,3-dichloroquinoxaline was treated either with p-nitrophenol followed by reduction of nitro groups, or with p-aminophenols to directly obtain the desired 2,3-(4-aminophenoxy)quinoxaline. This diamine was polymerized with 3,3',4,4'-biphenyldianhydride, 4

  20. 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.

  1. Multiphase design of autonomic self-healing thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Chen, Yulin; Kushner, Aaron M.; Williams, Gregory A.; Guan, Zhibin

    2012-06-01

    The development of polymers that can spontaneously repair themselves after mechanical damage would significantly improve the safety, lifetime, energy efficiency and environmental impact of man-made materials. Most approaches to self-healing materials require the input of external energy, healing agents, solvent or plasticizer. Despite intense research in this area, the synthesis of a stiff material with intrinsic self-healing ability remains a key challenge. Here, we show a design of multiphase supramolecular thermoplastic elastomers that combine high modulus and toughness with spontaneous healing capability. The designed hydrogen-bonding brush polymers self-assemble into a hard-soft microphase-separated system, combining the enhanced stiffness and toughness of nanocomposites with the self-healing capability of dynamic supramolecular assemblies. In contrast to previous self-healing polymers, this new system spontaneously self-heals as a single-component solid material at ambient conditions, without the need for any external stimulus, healing agent, plasticizer or solvent.

  2. Nanoscale pattern fidelity and transfer of hierarchically patterned thermoplastics films

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Kulkarni, Manish; Marshall, Allan; Douglas, Jack; Karim, Alamgir; the university of akron Team

    2015-03-01

    We demonstrate a versatile and inexpensive method for controlling the surface relief structure of both flexible elastomeric and glassy polymer films over large areas through a two-step imprinting process. First, nanoscale patterns were formed by nanoimprinting polymer films with a pattern on a DVD disk, obtained originally by nanoimprinting from a lithographically etched master pattern on a silicon wafer; micron-scale patterns were then superimposed on the nanoimprinted films by exposing them to ultraviolet radiation in oxygen (UVO) through a TEM grid mask having variable micron-scale patterning. This simple two-stage imprinting method allows for facile fabrication of hierarchically structured elastomer and thermoplastic polymer films. Besides, the thermodynamic properties of dewetting phenomenon of polystyrene film under the confinement of hierarchically patterned PDMS is studied.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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)

  8. Thermoplastic Polyurethanes with Isosorbide Chain Extender

    SciTech Connect

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

    2015-12-15

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

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

    SciTech Connect

    Bitler, S.P.; Kamp. D.A.; Yoon V.Y.

    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.

  10. Multi-scale thermal stability of a hard thermoplastic protein-based material

    NASA Astrophysics Data System (ADS)

    Latza, Victoria; Guerette, Paul A.; Ding, Dawei; Amini, Shahrouz; Kumar, Akshita; Schmidt, Ingo; Keating, Steven; Oxman, Neri; Weaver, James C.; Fratzl, Peter; Miserez, Ali; Masic, Admir

    2015-09-01

    Although thermoplastic materials are mostly derived from petro-chemicals, it would be highly desirable, from a sustainability perspective, to produce them instead from renewable biopolymers. Unfortunately, biopolymers exhibiting thermoplastic behaviour and which preserve their mechanical properties post processing are essentially non-existent. The robust sucker ring teeth (SRT) from squid and cuttlefish are one notable exception of thermoplastic biopolymers. Here we describe thermoplastic processing of squid SRT via hot extrusion of fibres, demonstrating the potential suitability of these materials for large-scale thermal forming. Using high-resolution in situ X-ray diffraction and vibrational spectroscopy, we elucidate the molecular and nanoscale features responsible for this behaviour and show that SRT consist of semi-crystalline polymers, whereby heat-resistant, nanocrystalline β-sheets embedded within an amorphous matrix are organized into a hexagonally packed nanofibrillar lattice. This study provides key insights for the molecular design of biomimetic protein- and peptide-based thermoplastic structural biopolymers with potential biomedical and 3D printing applications.

  11. Multi-scale thermal stability of a hard thermoplastic protein-based material

    PubMed Central

    Latza, Victoria; Guerette, Paul A.; Ding, Dawei; Amini, Shahrouz; Kumar, Akshita; Schmidt, Ingo; Keating, Steven; Oxman, Neri; Weaver, James C.; Fratzl, Peter; Miserez, Ali; Masic, Admir

    2015-01-01

    Although thermoplastic materials are mostly derived from petro-chemicals, it would be highly desirable, from a sustainability perspective, to produce them instead from renewable biopolymers. Unfortunately, biopolymers exhibiting thermoplastic behaviour and which preserve their mechanical properties post processing are essentially non-existent. The robust sucker ring teeth (SRT) from squid and cuttlefish are one notable exception of thermoplastic biopolymers. Here we describe thermoplastic processing of squid SRT via hot extrusion of fibres, demonstrating the potential suitability of these materials for large-scale thermal forming. Using high-resolution in situ X-ray diffraction and vibrational spectroscopy, we elucidate the molecular and nanoscale features responsible for this behaviour and show that SRT consist of semi-crystalline polymers, whereby heat-resistant, nanocrystalline β-sheets embedded within an amorphous matrix are organized into a hexagonally packed nanofibrillar lattice. This study provides key insights for the molecular design of biomimetic protein- and peptide-based thermoplastic structural biopolymers with potential biomedical and 3D printing applications. PMID:26387704

  12. Multi-scale thermal stability of a hard thermoplastic protein-based material.

    PubMed

    Latza, Victoria; Guerette, Paul A; Ding, Dawei; Amini, Shahrouz; Kumar, Akshita; Schmidt, Ingo; Keating, Steven; Oxman, Neri; Weaver, James C; Fratzl, Peter; Miserez, Ali; Masic, Admir

    2015-01-01

    Although thermoplastic materials are mostly derived from petro-chemicals, it would be highly desirable, from a sustainability perspective, to produce them instead from renewable biopolymers. Unfortunately, biopolymers exhibiting thermoplastic behaviour and which preserve their mechanical properties post processing are essentially non-existent. The robust sucker ring teeth (SRT) from squid and cuttlefish are one notable exception of thermoplastic biopolymers. Here we describe thermoplastic processing of squid SRT via hot extrusion of fibres, demonstrating the potential suitability of these materials for large-scale thermal forming. Using high-resolution in situ X-ray diffraction and vibrational spectroscopy, we elucidate the molecular and nanoscale features responsible for this behaviour and show that SRT consist of semi-crystalline polymers, whereby heat-resistant, nanocrystalline β-sheets embedded within an amorphous matrix are organized into a hexagonally packed nanofibrillar lattice. This study provides key insights for the molecular design of biomimetic protein- and peptide-based thermoplastic structural biopolymers with potential biomedical and 3D printing applications. PMID:26387704

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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.

  20. Thermoplastic film prevents proppant flowback

    SciTech Connect

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

    1996-02-05

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

  1. Joining of thermoplastic substrates by microwaves

    DOEpatents

    Paulauskas, Felix L.; Meek, Thomas T.

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wang, Dong

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

  3. Tough soluble aromatic thermoplastic copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    2000-01-01

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

  4. 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.

  5. Interlaminar fracture toughness of thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Hinkley, J. A.; Johnston, N. J.; Obrien, T. K.

    1988-01-01

    Edge delamination tension and double cantilever beam tests were used to characterize the interlaminar fracture toughness of continuous graphite-fiber composites made from experimental thermoplastic polyimides and a model thermoplastic. Residual thermal stresses, known to be significant in materials processed at high temperatures, were included in the edge delamination calculations. In the model thermoplastic system (polycarbonate matrix), surface properties of the graphite fiber were shown to be significant. Critical strain energy release rates for two different fibers having similar nominal tensile properties differed by 30 to 60 percent. The reason for the difference is not clear. Interlaminar toughness values for the thermoplastic polyimide composites (LARC-TPI and polyimidesulfone) were 3 to 4 in-lb/sq in. Scanning electron micrographs of the EDT fracture surfaces suggest poor fiber/matrix bonding. Residual thermal stresses account for up to 32 percent of the strain energy release in composites made from these high-temperature resins.

  6. 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.

  7. Interlaminar fracture toughness of thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.; Johnston, Norman J.; O'Brien, T. Kevin

    1989-01-01

    Edge delamination tension and double cantilever beam tests were used to characterize the interlaminar fracture toughness of continuous graphite-fiber composites made from experimental thermoplastic polyimides and a model thermoplastic. Residual thermal stresses, known to be significant in materials processed at high temperatures, were included in the edge delamination calculations. In the model thermoplastic system (polycarbonate matrix), surface properties of the graphite fiber were shown to be significant. Cricital strain energy release rates for two different fibers having similar nominal tensile properties differed by 30 to 60 percent. The reason for the difference is not clear. Interlaminar toughness values for the thermoplastic polyimide composites (LARC-TPI and polyimidesulfone) were 3 to 4 in-lb/sq in. Scanning electron micrographs of the EDT fracture surfaces suggest poor fiber/matrix bonding. Residual thermal stresses account for up to 32 percent of the strain energy release in composites made from these high-temperature resins.

  8. Thermoplastic vulcanizates: new materials of choice.

    PubMed

    Severyns, K

    2000-03-01

    Increasingly, thermoplastic vulcanizates of ethylene propylene diene monomer rubber-polypropylene are being specified for medical applications. This article describes their properties and advantages over thermoset rubbers and other conventional medical elastomeric materials. PMID:10915490

  9. 40 CFR Table 3 to Subpart Jjj of... - Group 1 Storage Vessels at Existing Affected Sources Producing the Listed Thermoplastics

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Affected Sources Producing the Listed Thermoplastics 3 Table 3 to Subpart JJJ of Part 63 Protection of... Hazardous Air Pollutant Emissions: Group IV Polymers and Resins Pt. 63, Subpt. JJJ, Table 3 Table 3 to Subpart JJJ of Part 63—Group 1 Storage Vessels at Existing Affected Sources Producing the...

  10. High Process Yield Rates of Thermoplastic Nanofluidic Devices using a Hybrid Thermal Assembly Technique

    PubMed Central

    Uba, Franklin I.; Hu, Bo; Weerakoon-Ratnayake, Kumuditha; Oliver-Calixte, Nyote; Soper, Steven A.

    2014-01-01

    Over the past decade, thermoplastics have been used as alternative substrates to glass and Si for microfluidic devices because of the diverse and robust fabrication protocols available for thermoplastics that can generate high production rates of the desired structures at low cost and with high replication fidelity, the extensive array of physiochemical properties they possess, and the simple surface activation strategies that can be employed to tune their surface chemistry appropriate for the intended application. While the advantages of polymer microfluidics are currently being realized, the evolution of thermoplastic-based nanofluidic devices is fraught with challenges. One challenge is assembly of the device, which consists of sealing a cover plate to the patterned fluidic substrate. Typically, channel collapse or substrate dissolution occurs during assembly making the device inoperable resulting in low process yield rates. In this work, we report a low temperature hybrid assembly approach for the generation of functional thermoplastic nanofluidic devices with high process yield rates (>90%) with a short total assembly time (16 min). The approach involves thermally sealing a high Tg (glass transition temperature) substrate containing the nanofluidic structures to a cover plate possessing a lower Tg. Nanofluidic devices with critical feature sizes ranging between 25 – 250 nm were fabricated in a thermoplastic substrate (Tg = 104°C) and sealed with a cover plate (Tg = 75°C) at a temperature significantly below the Tg of the substrate. Results obtained from sealing tests revealed that the integrity of the nanochannels remained intact after assembly and devices were useful for fluorescence imaging at high signal-to-noise ratios. The functionality of the assembled devices was demonstrated by studying the stretching and translocation dynamics of dsDNA in the enclosed thermoplastic nanofluidic channels. PMID:25511610

  11. Improved thermoplastic materials for offshore flexible pipes

    SciTech Connect

    Dawans, F.; Jarrin, J.; Hardy, J.

    1988-08-01

    Long-term aging tests representative of field operating conditions have been conducted on various thermoplastic materials proposed for the inner tube of flexible pipes for offshore drilling and production applications. In particular, experimental data are provided about the changes of the mechanical properties of selected thermoplastic materials owing to optimized formulation when the pipes are exposed over time to crude oil in the presence of gas and water.

  12. 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.

  13. 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.

  14. Thermoplastic polyurethane (TPU)/polyolefin (PO) blends

    NASA Astrophysics Data System (ADS)

    Lu, Qiwei

    Thermoplastic polyurethane (TPU) is a very important material with high versatility and superior physical properties. Melt blending TPU with metallocene polyolefin (PO) can lower TPU cost and improve polyolefin properties like abrasion resistance, adhesion, and paintability. Since TPU and non-polar PO blends are completely immiscible, efficient compatibilizers become the key issue and remain challenging. My main thesis work is to develop and study compatibilized TPU/PO blends. Although reactive compatibilization is considered the most efficient method, fast interfacial reactions between highly reactive functional groups are necessary to generate compatibilizers within usually short processing time. It is known that the urethane linkage (carbamate -NHCOO-) in TPU can reversibly dissociate to generate highly reactive isocyanates at melt temperatures. To find out the best reactive compatibilization, three approaches were employed on different molecular scales: (1) model urethane compound (dibutyl & dioctyl 4,4'-methylenebis(phenyl carbamate)) and small functional molecule (primary amine, secondary amine, hydroxyl, acid, anhydride, and epoxide) reactions at 200°C monitored by nuclear magnetic resonance and Fourier-transform infrared to examine the basic chemistry; (2) short, model TPU's with different chemical structures blended with functional polymers including poly(ethylene glycol) and polybutadiene to explore the effect of interface in immiscible mixtures; (3) melt blending of a commercial TPU with polypropylene (PP), further involving more complicated morphology, using different types of functional PP's (note: amine functional PP's were prepared by melt amination) as compatibilizers followed by rheological, morphological, thermal, and mechanical characterizations. Besides the core thesis project on TPU blends, other related work that has been accomplished includes: (1) adhesion between TPU and PP; (2) rheological properties of TPU; (3) block copolymer formation

  15. 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

  16. 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.

  17. 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

  18. Semi-interpenetrating polymer network's of polyimides: Fracture toughness

    NASA Technical Reports Server (NTRS)

    Hansen, Marion Glenn

    1988-01-01

    The objective was to improve the fracture toughness of the PMR-15 thermosetting polyimide by co-disolving LaRC-TPI, a thermoplastic polyimide. The co-solvation of a thermoplastic into a thermoset produces an interpenetration of the thermoplastic polymer into the thermoset polyimide network. A second research program was planned around the concept that to improve the fracture toughness of a thermoset polyimide polymer, the molecular weight between crosslink points would be an important macromolecular topological parameter in producing a fracture toughened semi-IPN polyimide.

  19. Renewable-resource thermoplastic elastomers based on polylactide and polymenthide.

    PubMed

    Wanamaker, Carolyn L; O'Leary, Leslie E; Lynd, Nathaniel A; Hillmyer, Marc A; Tolman, William B

    2007-11-01

    An alpha,omega-functionalized polymenthide was synthesized by the ring-opening polymerization of menthide in the presence of diethylene glycol with diethyl zinc as the catalyst. Termination with water afforded the dihydroxy polymenthide. The reaction of this telechelic polymer with triethylaluminum formed the corresponding aluminum alkoxide macroinitiator that was used for the controlled polymerization of lactide to yield biorenewable polylactide-b-polymenthide-b-polylactide triblock copolymers. The molecular weight and chemical composition were easily adjusted by the monomer-to-initiator ratios. Microphase separation in these triblock copolymers was confirmed by small-angle X-ray scattering and differential scanning calorimetry. A representative triblock was prepared with a hexagonally packed cylindrical morphology as determined by small-angle X-ray scattering, and tensile testing was employed to assess the mechanical behavior. On the basis of the ultimate elongations and elastic recovery, these triblock copolymers behaved as thermoplastic elastomers. PMID:17960909

  20. Microcellular Foams Based on High Performance Thermoplastic Nanocomposites

    SciTech Connect

    Sorrentino, Luigi; Iannace, Salvatore; Gargiulo, Marcella; Pezzullo, Giuseppe

    2010-06-02

    Foams from engineering thermoplastics nanocomposites based on Polyethersulphone and Polyethylene-2,6-naphthalate were prepared by using two different nanofillers (Silica nanoparticles and Graphite nanosheets). The effects of the nanofiller type and content on the foaming process was investigated and related to the density and cellular morphology of foams. The nanocomposite foams based on PES matrix exhibited improved nucleated cells both with SiO{sub 2} and Graphite nanosheets, but the density increased at all temperatures. On the contrary, nanocomposite foams based on PEN matrix showed different behaviors with the filler type. In this case, in fact, silica nanoparticles allowed lower densities when compared to the unfilled polymer foams, without influencing cells density. The Graphite nanosheets extended towards higher temperatures the foaming window of PEN nanocomposites, allowing densities as low as 0.15 at 260 deg. C.

  1. Thermoplastic Elastomers via polyolefin/Layered Silicate Nanocomposites

    NASA Astrophysics Data System (ADS)

    Kalluru, Sri; Cochran, Eric

    2013-03-01

    Here we report the synthesis of fully exfoliated polyolefin nanocomposites via Surface-Initiated Ring Opening Metathesis Polymerization (SI-ROMP). Montmorillonite (MMT) clay platelets were rendered hydrophobic through ion exchange with alkyl-ammonium surfactants terminated with norbornene. We were then able to form block copolymer brushes of (substituted) norbornenes and cyclopentene via SI-ROMP. Subsequent hydrogenation yielded highly crystalline polyethylene and rubbery saturated polynorbornenes, thus giving a thermoplastic elastomer. Nanocomposites were prepared with different nanofiller percentages and were characterized for morphological (XRD, TEM), thermal (TGA, DSC), and mechanical (DMA, Rheology) properties. Complete exfoliation of nanocomposites was confirmed by XRD and TEM. A fraction of the polymer brushes were subsequently removed from their substrate by reverse ion exchange and characterized in parallel with their corresponding nanocomposite analogs. In this way we were able to directly assess the role of the filler particle in the thermal properties, melt rheology, morphology, and tensile properties.

  2. 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.

  3. Development of Lignin-Based Polyurethane Thermoplastics

    SciTech Connect

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

    2013-01-01

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

  4. 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

  5. Plastic wastes as modifiers of the thermoplasticity of coal

    SciTech Connect

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

    2005-12-01

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

  6. 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.

  7. Environmentally degradable, high-performance thermoplastics from phenolic phytomonomers

    NASA Astrophysics Data System (ADS)

    Kaneko, Tatsuo; Thi, Tran Hang; Shi, Dong Jian; Akashi, Mitsuru

    2006-12-01

    Aliphatic polyesters, such as poly(lactic acid), which degrade by hydrolysis, from naturally occurring molecules form the main components of biodegradable plastics. However, these polyesters have become substitutes for only a small percentage of the currently used plastic materials because of their poor thermal and mechanical properties. Polymers that degrade into natural molecules and have a performance closer to that of engineering plastics would be highly desirable. Although the use of a high-strength filler such as a bacterial cellulose or modified lignin greatly increases the plastic properties, it is the matrix polymer that determines the intrinsic properties of the composite. The introduction of an aromatic component into the thermoplastic polymer backbone is an efficient method to intrinsically improve the material performance. Here, we report the preparation of environmentally degradable, liquid crystalline, wholly aromatic polyesters. The polyesters were derived from polymerizable plant-derived chemicals-in other words, `phytomonomers' that are widely present as lignin biosynthetic precursors. The mechanical performance of these materials surpasses that of current biodegradable plastics, with a mechanical strength, σ, of 63MPa, a Young's modulus, E, of 16GPa, and a maximum softening temperature of 169∘C. On light irradiation, their mechanical properties improved further and the rate of hydrolysis accelerated.

  8. Polyurethane thermoplastic elastomers with inherent radiopacity for biomedical applications.

    PubMed

    Kiran, S; James, Nirmala R; Jayakrishnan, A; Joseph, Roy

    2012-12-01

    Synthesis and characterization of three different radiopaque thermoplastic polyurethane elastomers are reported. Radiopacity was introduced to the polyurethanes by incorporating an iodinated chain extender, namely, 4,4'-isopropylidinedi-(2,6-diiodophenol) (IBPA), into the polymer chain during polyurethane synthesis. Radiopaque polyurethanes (RPUs) were synthesized by reacting 4,4'-methylenebis(phenyl isocyanate) (MDI), IBPA, and three different diols. The polyols used for the synthesis were polypropylene glycol, polycaprolactone diol, and poly(hexamethylene carbonate) diol. RPUs were characterized by infrared spectroscopy, contact angle measurements, thermogravimetry, dynamic mechanical analysis, energy dispersive X-ray analysis, gel permeation chromatography, X-ray fluorescence spectroscopy, and X-radiography. X-ray images showed that all RPUs prepared using IBPA as the chain extender are highly radiopaque compared with an Aluminum wedge of equivalent thickness. Elemental analysis revealed that the polyurethanes contained 18-19% iodine in the polymer matrix. The RPUs developed have radiopacity equivalent to that of a polymer filled with 20 wt % barium sulfate. Results revealed that RPUs of wide range of properties may be produced by incorporating different diols as the soft chain segment. Cell culture cytotoxicity studies conducted using L929 cells by direct contact test and MTT assay proved that these RPUs are noncytotoxic in nature. PMID:22815186

  9. Laser transmission welding of long glass fiber reinforced thermoplastics

    NASA Astrophysics Data System (ADS)

    van der Straeten, Kira; Engelmann, Christoph; Olowinsky, Alexander; Gillner, Arnold

    2015-03-01

    Joining fiber reinforced polymers is an important topic for lightweight construction. Since classical laser transmission welding techniques for polymers have been studied and established in industry for many years joint-strengths within the range of the base material can be achieved. Until now these processes are only used for unfilled and short glass fiber-reinforced thermoplastics using laser absorbing and laser transparent matrices. This knowledge is now transferred to joining long glass fiber reinforced PA6 with high fiber contents without any adhesive additives. As the polymer matrix and glass fibers increase the scattering of the laser beam inside the material, their optical properties, changing with material thickness and fiber content, influence the welding process and require high power lasers. In this article the influence of these material properties (fiber content, material thickness) and the welding parameters like joining speed, laser power and clamping pressure are researched and discussed in detail. The process is also investigated regarding its limitations. Additionally the gap bridging ability of the process is shown in relation to material properties and joining speed.

  10. 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.

  11. Recycling concepts for thermoplastic composites

    SciTech Connect

    Lochem, J.H. van; Henriksen, C.; Lund, H.H.

    1995-10-01

    Thermoplastic short fiber composite materials are increasingly being used as insulating materials in electricity distribution. Economically they possess good opportunities for material recycling and reuse due to the high virgin price. To investigate the recycling potential of post-consumer components, PPS40%GF and PBT30%GF, representing commonly used insulating materials, have been artificially aged and recycled. To simulate 10 years of service life, injection molded tensile bars have been aged in different environments varying temperature, humidity and pH. After accelerated aging, the aging state has been characterized by tensile and impact strength, viscoelastic behavior (DMTA), molecular weight, crystallinity (DSC) and fracture behavior (SEM). These properties have been compared to virgin material. The aged materials have been recycled by regranulation and compounds with different ratios virgin/aged material and different coupling agents to repair the glass-matrix interface. Injection molded compounds were characterized by short and long term properties. Recompounding PBT30%GF with virgin material and no added coupling agents results in a partial recovery of the fiber-matrix adhesion. Based on the first short-term characterizations PBT30%GF seems not very suitable for reuse in primary applications. PPS40%GF seems more suitable for reuse in primary applications after recycling. Although the short-term mechanical properties of the aged batches do not recover after recycling, the fiber-matrix adhesion improves especially when adding coupling agents. Further long-term testing in creep and humid environments during the remaining part of this project will show whether the improved interface properties make recycled materials valuable for reuse in various industrial applications.

  12. Determination of the strain rate dependent thermal softening behavior of thermoplastic materials for crash simulations

    NASA Astrophysics Data System (ADS)

    Hopmann, Christian; Klein, Jan; Schöngart, Maximilian

    2016-03-01

    Thermoplastic materials are increasingly used as a light weight replacement for metal, especially in automotive applications. Typical examples are frontends and bumpers. The loads on these structures are very often impulsive, for example in a crash situation. A high rate of loading causes a high strain rate in the material which has a major impact on the mechanical behavior of thermoplastic materials. The stiffness as well as the rigidity of polymers increases to higher strain rates. The increase of the mechanical properties is superimposed at higher rates of loading by another effect which works reducing on stiffness and rigidity, the increase of temperature caused by plastic deformation. The mechanical behavior of thermoplastic materials is influenced by temperature opposing to strain rate. The stiffness and rigidity are decreased to higher values of temperature. The effect of thermal softening on thermoplastic materials is investigated at IKV. For this purpose high-speed tensile tests are performed on a blend, consisting of Polybutylenterephthalate (PBT) and Polycarbonate (PC). In preliminary investigations the effects of strain rate on the thermomechanical behavior of thermoplastic materials was studied by different authors. Tensile impact as well as split Hopkinson pressure bar (SHPB) tests were conducted in combination with high-speed temperature measurement, though, the authors struggled especially with temperature measurement. This paper presents an approach which uses high-speed strain measurement to transpire the link between strain, strain rate and thermal softening as well as the interdependency between strain hardening and thermal softening. The results show a superimposition of strain hardening and thermal softening, which is consistent to preliminary investigations. The advantage of the presented research is that the results can be used to calibrate damage and material models to perform mechanical simulations using Finite Element Analysis.

  13. 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.

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

    DOE PAGESBeta

    Kempe, Michael D.; Miller, David C.; Wohlgemuth, John H.; Kurtz, Sarah R.; Moseley, John M.; Nobles, Dylan L.; Stika, Katherine M.; Brun, Yefim; Samuels, Sam L.; Shah, Qurat Annie; et al

    2016-01-08

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

  15. Composites of thermoplastic starch and nanoclays produced by extrusion and thermopressing.

    PubMed

    Müller, Carmen M O; Laurindo, João Borges; Yamashita, Fabio

    2012-06-20

    The aim of this study was to produce thermoplastic starch (TPS) films and to enhance their properties by reinforcing them with hydrophilic and hydrophobic nanoclays. TPS films were prepared by extrusion and thermopressing, and their crystallinity, water vapor permeability (WVP), and mechanical properties were studied. The hydrophilic nanoclay lowered the material WVP due to the formation of an intercalated composite. The hydrophobic nanoclays increased the rigidity of the films but did not alter the tensile strength. The blending of nanoclays with thermoplastic starch modifies the mechanical properties and WVP, and these changes are strongly associated with the dispersion of nanoclay in the polymer matrix. The dispersion, in turn, depends on the compatibility of the matrix and the nanoclay in terms of the hygroscopicity and the concentration in which the nanoclay is used. The addition of nanoclays to starch-based films is a promising way to enhance them for industrial manufacture. PMID:24750751

  16. 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.

  17. 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

  18. Thermoplastic starch/ethylene vinyl alcohol/forsterite nanocomposite as a candidate material for bone tissue engineering.

    PubMed

    Mahdieh, Zahra; Bagheri, Reza; Eslami, Masoud; Amiri, Mohammad; Shokrgozar, Mohammad Ali; Mehrjoo, Morteza

    2016-12-01

    Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples, respectively. With blending thermoplastic starch and ethylene vinyl alcohol, some properties of thermoplastic starch such as degradation rate and water absorption were modified. In addition, using nanoforsterite as the ceramic reinforcing phase resulted in the improvement of mechanical and biological traits. The addition of nanoforsterite decreased the weight loss of the thermoplastic starch and ethylene vinyl alcohol blend in simulated body fluid. Moreover, this addition modified the pH in the MTT (methyl thiazolyl tetrazolium) assay and stimulated the cell proliferation. Cell adhesion assays indicated a favorable interaction between cells and the biomaterial. The proposed nanocomposite has appropriate biocompatibility, as well as mechanical properties in order to be used in bone tissue engineering. PMID:27612717

  19. Deformational characteristics of thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Indukuri, Kishore K.

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

  20. Ultrasonic Welding of Graphite/Thermoplastic Composite

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  1. Thermoplastic Composite Materials for Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Casula, G.; Lenzi, F.; Vitiello, C.

    2008-08-01

    Mechanical and thermo-physical properties of composites materials with thermoplastic matrix (PEEK/IM7, TPI/IM7 and PPS/IM7) used for aerospace applications have been analyzed as function of two different process techniques: compression molding and fiber placement process "hot gas assisted."

  2. Biodegradation Of thermoplastic polyurethanes from vegetable oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  3. Imprint Molding of a Microfluidic Optical Cell on Thermoplastics with Reduced Surface Roughness for the Detection of Copper Ions.

    PubMed

    Wu, Jing; Lee, Nae Yoon

    2016-01-01

    Here, we introduce a simple and facile technique for fabricating microfluidic optical cells by utilizing a micropatterned polymer mold, followed by imprinting on thermoplastic substrates. This process has reduced the surface roughness of the microchannel, making it suitable for microscale optical measurements. The micropatterned polymer mold was fabricated by first micromilling on a poly(methylmethacrylate) (PMMA) substrate, and then transferring the micropattern onto an ultraviolet (UV)-curable optical adhesive. After an anti-adhesion treatment of the polymer mold fabricated using the UV-curable optical adhesive, the polymer mold was used repeatedly for imprinting onto various thermoplastics, such as PMMA, polycarbonate (PC), and poly(ethyleneterephthalate) (PET). The roughness values for the PMMA, PC, and PET microchannels were approximately 11.3, 20.3, and 14.2 nm, respectively, as compared to those obtained by micromilling alone, which were 15.9, 76.8, and 207.5 nm, respectively. Using the imprint-molded thermoplastic optical cell, rhodamine B and copper ions were successfully quantified. The reduced roughness of the microchannel surface resulted in improved sensitivity and reduced noise, paving the way for integration of the detection module so as to realize totally integrated microdevices. PMID:26753711

  4. Thermoplastic processing of proteins for film formation--a review.

    PubMed

    Hernandez-Izquierdo, V M; Krochta, J M

    2008-03-01

    Increasing interest in high-quality food products with increased shelf life and reduced environmental impact has encouraged the study and development of edible and/or biodegradable polymer films and coatings. Edible films provide the opportunity to effectively control mass transfer among different components in a food or between the food and its surrounding environment. The diversity of proteins that results from an almost limitless number of side-chain amino-acid sequential arrangements allows for a wide range of interactions and chemical reactions to take place as proteins denature and cross-link during heat processing. Proteins such as wheat gluten, corn zein, soy protein, myofibrillar proteins, and whey proteins have been successfully formed into films using thermoplastic processes such as compression molding and extrusion. Thermoplastic processing can result in a highly efficient manufacturing method with commercial potential for large-scale production of edible films due to the low moisture levels, high temperatures, and short times used. Addition of water, glycerol, sorbitol, sucrose, and other plasticizers allows the proteins to undergo the glass transition and facilitates deformation and processability without thermal degradation. Target film variables, important in predicting biopackage performance under various conditions, include mechanical, thermal, barrier, and microstructural properties. Comparisons of film properties should be made with care since results depend on parameters such as film-forming materials, film formulation, fabrication method, operating conditions, testing equipment, and testing conditions. Film applications include their use as wraps, pouches, bags, casings, and sachets to protect foods, reduce waste, and improve package recyclability. PMID:18298745

  5. Tunable optical response of bowtie nanoantenna arrays on thermoplastic substrates

    NASA Astrophysics Data System (ADS)

    Sharac, N.; Sharma, H.; Veysi, M.; Sanderson, R. N.; Khine, M.; Capolino, F.; Ragan, R.

    2016-03-01

    Thermally responsive polymers present an interesting avenue for tuning the optical properties of nanomaterials on their surfaces by varying their periodicity and shape using facile processing methods. Gold bowtie nanoantenna arrays are fabricated using nanosphere lithography on prestressed polyolefin (PO), a thermoplastic polymer, and optical properties are investigated via a combination of spectroscopy and electromagnetic simulations to correlate shape evolution with optical response. Geometric features of bowtie nanoantennas evolve by annealing at temperatures between 105 °C and 135 °C by releasing the degree of prestress in PO. Due to the higher modulus of Au versus PO, compressive stress occurs on Au bowtie regions on PO, which leads to surface buckling at the two highest annealing temperatures; regions with a 5 nm gap between bowtie nanoantennas are observed and the average reduction is 75%. Reflectance spectroscopy and full-wave electromagnetic simulations both demonstrate the ability to tune the plasmon resonance wavelength with a window of approximately 90 nm in the range of annealing temperatures investigated. Surface-enhanced Raman scattering measurements demonstrate that maximum enhancement is observed as the excitation wavelength approaches the plasmon resonance of Au bowtie nanoantennas. Both the size and morphology tunability offered by PO allows for customizing optical response.

  6. 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.

  7. 3-D stamp forming of thermoplastic matrix composites

    NASA Astrophysics Data System (ADS)

    Hou, M.; Friedrich, K.

    1994-03-01

    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 laminates are heated by contact heating in an external heater up to about 120°C above the glass transition temperature ( T g) of the polymer matrix; they are then stamp formed in a cold matched metal tool. Typical cycle times (including preheating time of the preconsolidated laminates) are in the range of 3 min. Useful processing conditions, such as stamping temperature, stamping velocity and hold-down pressure required for stamp forming of this composite are determined. In addition the effect of die geometries (deformation radian) and original laminate dimensions are studied. The results describe the correlations between processing parameters and fiber buckling. Finally the thickness distribution in stamped parts are investigated in relation to different directions of fiber orientation.

  8. 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.

  9. Novel compostable materials based upon thermoplastic polyurethanes and native starch and the production of films thereof

    SciTech Connect

    Seidenstuecker, T.; Fritz, H.G.

    1996-12-31

    Certain types of thermoplastic poly(urethanes) (TPU) are biodegradable. The biodegradability depends upon the structure of the polymer chains. Effective chain scission can only be catalysed by enzymes, which occur abundantly in compost environments, if functional groups are present in the backbone that are highly prone to hydrolysis. Especially certain thermoplastic polyesters were found to be biodegradable. In terms of TPUs the proneness to hydrolysis can be achieved be synthesizing thermoplastic poly(ester-urethanes) that contain as many aster-bonds as possible alongside the backbone. We have investigated the degradability of different types of TPUs in various environments. The incorporation of native starch not only increases the rate of degradation but alters the material properties. This alternation of properties depends upon the filler content and type of starch incorporated. For instance, the higher the starch content is the stiffer the compound becomes. Here it was possible to incorporate up to 70 wt. % of starch. Also, using these components it could be confirmed that special types of starch with small medium particle diameters (< 10 {mu}m) have higher tensile properties and are stiffer compared to native starch with particle diameters above 10 {mu}m. The production of films with various compounds is possible and important film properties as well as applications will be introduced.

  10. Process optimization of a thermoplastic polyimidesulphone

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    The detailed characterization of an experimental thermoplastic polyimidesulfane 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 measurement. 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.

  11. The role of molecular mobility in the consolidation and bonding of thermoplastic composite materials

    SciTech Connect

    Agarwal, V.

    1991-01-01

    The time required to consolidate thermoplastic composite materials was determined using isothermal compression molding and laser-assisted consolidation experiments; very short consolidation times, less than one second, were obtained using the laser process. Characterization of parts produced using the laser process included measuring interlaminar properties, void content, polymer degradation, and crystallinity. A nonisothermal diffusional bonding model was developed to determine whether the experimental interlaminar properties were consistent with a molecular interdiffusion mechanism. Model predictions were found to be consistent with experimental results. Theoretical self-diffusivities and relaxation times were calculated for the polymer resin using the reptation theory for polymer melts. These predictions were compared to experimental measurements of the relaxation times using rheometric experiments. The isothermal bonding time obtained from the laser consolidation experiments was comparable to the experimental relaxation times. Comparison of the theoretical predictions indicated that the bonding was controlled by the longer, less mobile chains in the resin system.

  12. 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

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

    PubMed

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

    2014-01-01

    Bio-based polymer materials from renewable resources have recently become a growing research focus. Herein, a novel thermoplastic elastomer is developed via controlled/living radical polymerization of plant-derived itaconic acid derivatives, which are some of the most abundant renewable acrylic monomers obtained via the fermentation of starch. The reversible addition-fragmentation chain-transfer (RAFT) polymerizations of itaconic acid imides, such as N-phenylitaconimide and N-(p-tolyl)itaconimide, and itaconic acid esters, such as di-n-butyl itaconate and bis(2-ethylhexyl) itaconate, are examined using a series of RAFT agents to afford well-defined polymers. The number-average molecular weights of these polymers increase with the monomer conversion while retaining relatively narrow molecular weight distributions. Based on the successful controlled/living polymerization, sequential block copolymerization is subsequently investigated using mono- and di-functional RAFT agents to produce block copolymers with soft poly(itaconate) and hard poly(itaconimide) segments. The properties of the obtained triblock copolymer are evaluated as bio-based acrylic thermoplastic elastomers. PMID:24243816

  14. PEKK as a new thermoplastic matrix for high-performance composites

    SciTech Connect

    Chang, I.Y.

    1988-07-01

    A novel semicrystalline polyetherketoneketone (PEKK) polymer is being developed as a potential high-performance thermoplastic matrix system for advanced composites. This resin with upper use temperature between those of Du Pont's K-3 (polyimide) and J-2 (polyamide) has potential advantages versus other commercial organic matrix systems. The carbon-fiber reinforced composite laminates with PEKK matrix prepared from the proprietary melt impregnated tows showed high flexural, shear, and compressive strengths, excellent environmental durability and hot-wet stability. PEKK neat resin and its carbon composite properties are presented and discussed. 4 references, 4 figures, 4 tables.

  15. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

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

    2011-05-04

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

  16. Using imprinting technology to fabricate three-dimensional devices from moulds of thermosetting polymer patterns

    NASA Astrophysics Data System (ADS)

    Chen, Jem-Kun; Ko, Fu-Hsiang; Chan, Chia-Hao; Huang, Chih-Feng; Chang, Feng-Chih

    2006-09-01

    The fabrication of moulds for imprinting can be simplified significantly by using specialized cross-linking polymers to define the pattern on a silicon wafer. Thermosetting polymers (SU-8) can be used to pattern silicon moulds for imprinting technologies because (1) silicon oxide moulds bearing a thermosetting polymer pattern can be obtained using conventional semiconductor technologies and (2) thermosetting polymers have no obvious glass transition temperature (Tg) because of their cross-linked structure, but the hardness decreases significantly when the temperature is above the Tg. In this study, we used Su-8 resist as the thermosetting polymer pattern to obtain moulds on a silicon wafer. We have tested the thermal properties of thermosetting (SU-8) and thermoplastic polymers (22A4) for use as imprinting patterns and imprinted resists. We fabricated a hill-like structure by applying an electron beam strategy and used this thick film to increase the adhesion between the pattern and the silicon wafer. We used scanning electron microscopy to investigate the resolution of the thermoplastic polymer resist (22A4) pattern that we imprinted using the thermosetting polymer (SU-8) pattern. To define the feature size after imprinting, we determined the feature size shrink factor after separation of the thermosetting polymer pattern (SU-8) from the thermoplastic polymer (22A4) resist. In addition, we have fabricated a microlens of polydimethylsiloxane (PDMS) through replication using the thermoplastic polymer resist (22A4) obtained after imprinting the mould with the microlens structure of the thermosetting polymer (SU-8).

  17. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1969-01-01

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

  19. Biosynthesis of novel thermoplastic polythioesters by engineered Escherichia coli

    NASA Astrophysics Data System (ADS)

    Lütke-Eversloh, Tina; Fischer, Andreas; Remminghorst, Uwe; Kawada, Jumpei; Marchessault, Robert H.; Bögershausen, Ansgar; Kalwei, Martin; Eckert, Hellmut; Reichelt, Rudolf; Liu, Shuang-Jiang; Steinbüchel, Alexander

    2002-12-01

    The development of non-petrochemical sources for the plastics industry continues to progress as large multinationals focus on renewable resources to replace fossil carbon. Many bacteria are known to accumulate polyoxoesters as water-insoluble granules in the cytoplasm. The thermoplastic and/or elastomeric behaviour of these biodegradable polymers holds promise for the development of various technological applications. Here, we report the synthesis and characterization of microbial polythioesters (PTEs), a novel class of biopolymers of general technological relevance. Biosynthesis of PTE homopolymers was achieved using a recombinant strain of Escherichia coli that expressed a non-natural pathway consisting of a butyrate kinase, a phosphotransbutyrylase, and a PHA synthase. Different homopolymers were produced, consisting of either 3-mercaptopropionate, 3-mercaptobutyrate, or 3-mercaptovalerate repeating units, if the respective mercaptoalkanoic acids were provided as precursor substrates to the fermentative process. The PTEs contributed up to 30% (w/w) of the cellular dry weight and were identified as hydrophobic inclusions in the cytoplasm. The chemical and stereochemical homogeneity of the purified PTEs were identified by different methods, and the estimated physical properties were compared to the oxypolyester equivalents, revealing low crystalline order and, for the poly(3-mercaptopropionate) improved thermal stability. The ability to produce PTEs through a biosynthetic route opens up new avenues in the field of biomaterials.

  20. Thermoplastic polymeric adhesive for structural bonding applications for orthopaedic devices

    SciTech Connect

    Devanathan, D.; King, R.; Swarts, D.; Lin, S.; Ramani, K.; Tagle, J.

    1994-12-31

    The orthopaedics industry has witnessed tremendous growth in recent years primarily due to the introduction of high performance, porous coated implants. These devices have eliminated the need for the use of bone cement for in vivo implant fixation, replacing it with the ingrowth of bone into the porous surfaces. The metallurgical bonding processes used for attaching the porous to the implant body introduce some undesirable effect i.e., the reduction of the fatigue strength of the implant due to the ``notches`` created and also due to the high temperature exposure during the sintering operations. This paper describes the development of a thermoplastic polymeric adhesive based structural bonding technique. The high performance polymeric adhesive is fully characterized with respect to its intended application. The design of the porous layer is optimized to achieve a reliable bond to the implant. A thermal heating/cooling process was developed to control the final polymer morphology. Static and fatigue tests were conducted to fully characterize the adhesive bond strength. A ring shear test method was developed to determine the shear strength of the bond interface. Besides the characterization of the adhesive bond, the joints will be analyzed using finite element models. The correlation between the analytical models and the

  1. 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.

  2. Multiblock thermoplastic polyurethanes for biomedical and shape memory applications

    NASA Astrophysics Data System (ADS)

    Gu, Xinzhu

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

  3. Program For Two-Dimensional Thermoplastic Deformation

    NASA Technical Reports Server (NTRS)

    Orient, George E.

    1993-01-01

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

  4. Trigeminal trophic syndrome treated with thermoplastic occlusion.

    PubMed

    Kurien, Anil M; Damian, Diona L; Moloney, Fergal J

    2011-02-01

    A 72-year-old man with a history of thrombotic CVA causing lateral medullary infarction presented with non-healing ulcers of the right side of the face of 5 months' duration. After extensive investigations, a diagnosis of trigeminal trophic syndrome was made. The ulcers progressed relentlessly despite amitriptyline and gabapentin, and he was treated with a combination of carbamazepine and thermoplastic mask occlusion of the right side of his face. Over the next 10 weeks the shallower facial ulcers began to diminish in depth and diameter, and the deeper ulcers stopped progressing. Although the patient showed early signs of healing, he died because of complications from the CVA. PMID:21332680

  5. Development of thermoplastic coated multifunctional transmission elements

    NASA Astrophysics Data System (ADS)

    Golaz, B.; Michaud, V.; de Oliveira, R.; Månson, J.-A. E.

    2012-04-01

    We report on key challenges of the development of steel cords reinforced thermoplastic elastomer composites with smart functionalities: adhesion tailoring for a durable mechanical load transfer through steel cords or other transmission elements by the use of surface treatments and primers, and integrated distributed temperature and strain sensing by the use of embedded fiber optic sensors. Traditional surface treatments including silane coupling agent were outperformed in processing time, adhesion and durability by a fast-curing coupling method using a UV-curable primer; and the integrated distributed temperature and strain sensing capability was demonstrated. The practical applications of the resulting multifunctional transmission element are then discussed in light of these results.

  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. Thermal decomposition of nano-enabled thermoplastics: Possible environmental health and safety implications.

    PubMed

    Sotiriou, Georgios A; Singh, Dilpreet; Zhang, Fang; Chalbot, Marie-Cecile G; Spielman-Sun, Eleanor; Hoering, Lutz; Kavouras, Ilias G; Lowry, Gregory V; Wohlleben, Wendel; Demokritou, Philip

    2016-03-15

    Nano-enabled products (NEPs) are currently part of our life prompting for detailed investigation of potential nano-release across their life-cycle. Particularly interesting is their end-of-life thermal decomposition scenario. Here, we examine the thermal decomposition of widely used NEPs, namely thermoplastic nanocomposites, and assess the properties of the byproducts (released aerosol and residual ash) and possible environmental health and safety implications. We focus on establishing a fundamental understanding on the effect of thermal decomposition parameters, such as polymer matrix, nanofiller properties, decomposition temperature, on the properties of byproducts using a recently-developed lab-based experimental integrated platform. Our results indicate that thermoplastic polymer matrix strongly influences size and morphology of released aerosol, while there was minimal but detectable nano-release, especially when inorganic nanofillers were used. The chemical composition of the released aerosol was found not to be strongly influenced by the presence of nanofiller at least for the low, industry-relevant loadings assessed here. Furthermore, the morphology and composition of residual ash was found to be strongly influenced by the presence of nanofiller. The findings presented here on thermal decomposition/incineration of NEPs raise important questions and concerns regarding the potential fate and transport of released engineered nanomaterials in environmental media and potential environmental health and safety implications. PMID:26642449

  8. [Effect of methods of sterilization on thermoplastics with special reference to modified surfaces].

    PubMed

    Müller, T; Käufer, H

    1999-01-01

    For materials intended for use in the medical setting their sterilizability is an indispensable prerequisite. In the case of most polymers the usual sterilization methods result in changes that even extend to cleavage of the polymer chains. A particular problem in this respect are the surfaces modified for improved biocompatibility investigated in the present study, which are characterised by enlarged contact areas. For this reason, possible changes to three different thermoplastics commonly used for medical applications (polyethylene, thermoplastic polyurethane, polycarbonate) were investigated. Steam, gas and radiation were used for sterilization. Tensile tests were employed to identify changes in mucosal characteristics caused by different sterilization techniques irrespective of the surface modification. Sterilization-related changes to the structure of the modified surfaces were investigated with the scanning electron microscope (SEM). Differential thermo analysis (DTA) was used to determine changes in the thermal characteristics of the plastics. Clear tendencies with regard to the behaviour of the plastics after sterilization with various techniques were found. A general statement about the compatibility of plastic materials with a specific sterilization method is not possible on the basis of this study. For every new polymeric product used for medical purposes, the characteristics required must first be defined and compliance with the permissible variations of these characteristics investigated for each of the various sterilization techniques available. PMID:10194878

  9. Microgravity Effects on Combustion of Polymers

    NASA Technical Reports Server (NTRS)

    Hirsch, David; Williams, Jim; Beeson, Harold

    2007-01-01

    A viewgraph presentation describing various microgravity effects on the combustion of polymers is shown. The topics include: 1) Major combustion processes and controlling mechanisms in normal and microgravity environments; 2) Review of some buoyancy effects on combustion: melting of thermoplastics; flame strength, geometry and temperature; smoldering combustion; 3) Video comparing polymeric rods burning in normal and microgravity environments; and 4) Relation to spacecraft fire safety of current knowledge of polymers microgravity combustion.

  10. Characterization of a thermoset-thermoplastic interphase using the atomic force microscope

    SciTech Connect

    Gruber, N.D.; Lesko, J.J.; Harris, L.A.

    1996-12-31

    Recent investigators have shown that the performance of polymer matrix composites can be significantly enhanced by using fibers sized with a thermoplastic polymer. This increase in performance is a result of the sizing material interacting with the matrix resin to form an interphase: a region possessing a gradient in properties different from the sizing material and the matrix resin. Although the influence of the sizing (interphase) on laminate properties has been well documented, quantitative information regarding interphase properties is absent. In this study, {open_quotes}model{close_quotes} composites consisting of polyurethane sized carbon fibers embedded in a vinyl ester matrix were fabricated to characterize the interphase. The atomic force microscope was used to identify the interphase region in these {open_quotes}model{close_quotes} composites.

  11. 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

  12. Characterization of poly(butylene succinate)/glycerol co-plasticized thermoplastic gelatin prepared by melt blending

    NASA Astrophysics Data System (ADS)

    Oliviero, Maria; Sorrentino, Andrea; Iannace, Salvatore

    2015-12-01

    Biodegradable thermoplastic poly(butylene succinate)/gelatin (PBS/TPG) blends with various blending ratios were prepared by melt mixing technique. The main goal of these blends is to improve the water sensitivity of thermoplastic gelatin by blending it with a hydrophobic biodegradable polymer obtained also from renewable resources. The incorporation of PBS yielded a decrease in absorbed moisture. Under the relative humidity 50 and 100%, the absorbed moisture obtained values were 19 and 229% for pure TPG, 12.3 and 127% for TPG/PBS(80/20), and 1.7 and 37% for TPG/PBS(20/80), respectively. The water resistance increased only for the samples containing a high value of PBS (>40%wt). Furthermore, mechanical properties and morphological analyses revealed that PBS/TPG blends were immiscible.

  13. Supportability evaluation of thermoplastic and thermoset composites

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  14. Low Cost Processing of Commingled Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    Chiasson, Matthew Lee

    A low cost vacuum consolidation process has been investigated for use with commingled thermoplastic matrix composites. In particular, the vacuum consolidation behaviour of commingled polypropylene/glass fibre and commingled nylon/carbon fibre precursors were studied. Laminates were consolidated in a convection oven under vacuum pressure. During processing, the consolidation of the laminate packs was measured by use of non-contact eddy current sensors. The consolidation curves are then used to tune an empirical consolidation model. The overall quality of the resulting laminates is also discussed. Dynamic mechanical analysis, differential scanning calorimetry and mechanical tensile testing were also performed in order to determine the effects of varying processing parameters on the physical and mechanical properties of the laminates. Through this analysis, it was determined that the nylon/carbon fibre blend was not suitable for vacuum consolidation, while the polypropylene/glass fibre blend is a viable option for vacuum consolidation. The ultimate goal of this work is to provide a foundation from which low cost unmanned aerial vehicle (UAV) components can be designed and manufactured from thermoplastic matrix composites using a low cost processing technique as an alternative to traditional thermoset composite materials.

  15. Soft Semicrystalline Thermoplastic Elastomers by Arrested Crystallization

    NASA Astrophysics Data System (ADS)

    Burns, Adam; Register, Richard

    2014-03-01

    Thermoplastic elastomers (TPEs) marry the solid-state behavior of vulcanized rubbers with the melt processability of thermoplastics. Archetypal soft TPEs consist of triblock copolymers comprising a rubbery mid-block flanked by two identical glassy end-blocks. Incorporating crystalline blocks into TPEs can confer solvent resistance as well as reduce the processing costs by giving access to single-phase melts. However, simply substituting crystalline for glassy end-blocks dramatically degrades the solid-state mechanical properties, particularly at large strains. We seek to integrate the benefits of crystallinity into TPEs, while maintaining the desired mechanical properties, using the block architecture: crystalline-glassy-rubbery-glassy-crystalline. Methods have been developed to synthesize highly symmetric, narrow-distribution block copolymers with this architecture using anionic polymerization of butadiene, styrene, and isoprene followed by hydrogenation. Judicious choices of block molecular weights indeed yield homogeneous melts above the melting point of the crystalline component. Upon cooling, crystallization--rather than interblock repulsion--establishes the solid-state microstructure which physically crosslinks the rubbery mid-block, ultimately conferring elasticity. Subsequent vitrification of the adjacent glassy blocks arrests the growth of the crystallites, and protects them from yielding under applied load. As a result, our materials show low initial moduli, strain hardening, and high extensibility, typical of commercial TPEs.

  16. 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.

  17. Conducting polymer ultracapacitor

    DOEpatents

    Shi, Steven Z.; Davey, John R.; Gottesfeld, Shimshon; Ren, Xiaoming

    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.

  18. ACT/ICAPS: Thermoplastic composite activities

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  19. Thermoplastic microcantilevers fabricated by nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Greve, Anders; Keller, Stephan; Vig, Asger L.; Kristensen, Anders; Larsson, David; Yvind, Kresten; Hvam, Jørn M.; Cerruti, Marta; Majumdar, Arunava; Boisen, Anja

    2010-01-01

    Nanoimprint lithography has been exploited to fabricate micrometre-sized cantilevers in thermoplastic. This technique allows for very well defined microcantilevers and gives the possibility of embedding structures into the cantilever surface. The microcantilevers are fabricated in TOPAS and are up to 500 µm long, 100 µm wide, and 4.5 µm thick. Some of the cantilevers have built-in ripple surface structures with heights of 800 nm and pitches of 4 µm. The yield for the cantilever fabrication is 95% and the initial out-of-plane bending is below 10 µm. The stiffness of the cantilevers is measured by deflecting the cantilever with a well-characterized AFM probe. An average stiffness of 61.3 mN m-1 is found. Preliminary tests with water vapour indicate that the microcantilevers can be used directly for vapour sensing applications and illustrate the influence of surface structuring of the cantilevers.

  20. 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.

  1. Monitoring impact damaging of thermoplastic composites

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  2. Life prediction of elastomeric and thermoplastic components

    SciTech Connect

    Stevenson, A.

    1994-12-31

    Life prediction tests for polymeric materials have been in use for a considerable period of time. However there are still fundamental problems with their usage and interpretation in terms of engineering performance. In particular, it is not yet in general possible to relate the rate of change of physical properties that arise as a consequence of chemical aging to the rate of change in the underlying chemical structure or morphology. Also, different physical properties may change at different rates and these materials are generally non-linear. This renders accelerated life prediction testing potentially unreliable. This paper reviews this general problem area and discusses advances which need to be made with respect to the roles of the permeation of fluids, mechanical fatigue crack growth and time dependent changes. Illustrative examples are discussed of both thermoplastics and crosslinked elastomers. Finally, a general scheme is discussed for future research in this area, related to the development of interactive numerical modelling.

  3. Long-short fiber reinforced thermoplastics

    SciTech Connect

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

    1986-01-01

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

  4. Microfluidic device fabrication by thermoplastic hot-embossing.

    PubMed

    Yang, Shuang; Devoe, Don L

    2013-01-01

    Due to their low cost compatibility with replication-based fabrication methods, thermoplastics represent an exceptionally attractive family of materials for the fabrication of lab-on-a-chip platforms. A diverse range of thermoplastic materials suitable for microfluidic fabrication is available, offering a wide selection of mechanical and chemical properties that can be leveraged and further tailored for specific applications. While high-throughput embossing methods such as reel-to-reel processing of thermoplastics is an attractive method for industrial microfluidic chip production, the use of single chip hot embossing is a cost-effective technique for realizing high-quality microfluidic devices during the prototyping stage. Here we describe methods for the replication of microscale features in two thermoplastics, polymethylmethacrylate (PMMA) and polycarbonate (PC), using hot embossing from a silicon template fabricated by deep reactive-ion etching. PMID:23329439

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

    SciTech Connect

    2009-02-01

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

  6. Heating of thermoplastic-based unidirectional composite prepregs

    SciTech Connect

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

    1989-04-01

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

  7. 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)

  8. Forming of fiber reinforced thermoplastic sheets

    SciTech Connect

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

    1993-12-31

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

  9. Triclosan antimicrobial polymers

    PubMed Central

    Petersen, Richard C.

    2016-01-01

    Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers that set on cooling

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

    DOEpatents

    Soroushian, Parviz

    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.