Sample records for thermoplastic puncture-healing polymers

  1. Bonding thermoplastic polymers

    DOEpatents

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

    2008-06-24

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

  2. 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.

  3. Method of forming a foamed thermoplastic polymer

    DOEpatents

    Duchane, David V. (Los Alamos, NM); Cash, David L. (Los Alamos, NM)

    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.

  4. Bonding of thermoplastic polymer microfluidics

    Microsoft Academic Search

    Chia-Wen Tsao; Don L. DeVoe

    2009-01-01

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

  5. Method of forming a foamed thermoplastic polymer

    DOEpatents

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

    1984-11-21

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

  6. 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.

  7. 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.

  8. Novel polymer blends with thermoplastic starch

    NASA Astrophysics Data System (ADS)

    Taghizadeh, Ata

    A new class of polymers known as "bioplastics" has emerged and is expanding rapidly. This class consists of polymers that are either bio-based or biodegradable, or both. Among these, polysaccharides, namely starch, are of great interest for several reasons. By gelatinizing starch via plasticizers, it can be processed in the same way as thermoplastic polymers with conventional processing equipment. Hence, these bio-based and biodegradable plastics, with their low source and refinery costs, as well as relatively easy processability, have made them ideal candidates for incorporation into various current plastic products. Four different plasticizers have been chosen here for gelatinization of thermoplastic starch (TPS): glycerol, sorbitol, diglycerol and polyglycerol, with the latter two being used for the first time in such a process. Two methodological categories are used. The first involves a calorimetric method (Differential Scanning Calorimetry) as well as optical microscopy; these are "static" methods where no shear is applied A wide range of starch/water/plasticizer compositions were prepared to explore the gelatinization regime for each plasticizer. The onset and conclusion gelatinization temperatures for sorbitol and glycerol were found to be in the same vicinity, while diglycerol and polyglycerol showed significantly higher transition temperatures. The higher molecular weight and viscosity of polyglycerol allow this transition to occur at an even higher temperature than with diglycerol. This is due to the increase in molecular weight and viscosity of the two new plasticizers, as well as their significant decrease in water solubility. It is demonstrated that the water/plasticizer ratio has a pronounced effect on gelatinization temperatures. When plasticizer content was held constant and water content was increased, it was found that the gelatinization temperature decreased for all the plasticizers. Meanwhile, when the water content was held constant and the plasticizer content was increased, the gelatinization temperature increased for glycerol, sorbitol and diglycerol, but it moved in the opposite direction in the case of polyglycerol. The gelatinization temperature variation for glycerol, sorbitol and diglycerol caused by changing water and plasticizer content indicates that water is the primary agent causing granular swell and plasticization in the gelatinization process. Due to the high molecular weight and viscosity, as well as the low hydroxyl group density (~ one --OH per two carbon) and borderline solubility of polyglycerol in water, it is believed that water-aided penetration of the plasticizer among the crystalline structure of starch molecules is significantly decelerated. So it is proposed that in the case of low-water solubility of the plasticizers, gelatinization temperature is determined more by the total amount of the plasticizer and water, rather than the water/plasticizer ratio. Increasing the miscibility of polyglycerol in water by increasing the temperature of the initial slurry, results in a return of the system to the typical thermal dependence of gelatinization with plasticizer/water ratio. Secondly, the gelatinization of starch under "dynamic conditions" was studied. In this case, a constant shear is applied to the slurry, along with a temperature ramp to induce gelatinization. This is, in fact, a rheological technique that heats up the slurry, while a mechanical shear is applied throughout. The reason for using this method is that in the plastic industry, thermoplastic starch is produced via processes involving shear such as extrusion, but, to date, there has not yet been a thorough study on the effect of pure shear on the gelatinization process. Glycerol, diglycerol and sorbitol were subjected to different dynamic gelatinization treatments in a couette flow system, and the results were compared with static gelatinization. Applying shear showed virtually no effect on the onset gelatinization temperature. However, the conclusion temperature was remarkably reduced

  9. Processing and Characterization of Jute Fiber Reinforced Thermoplastic Polymers

    Microsoft Academic Search

    A. C. Karmaker; G. Hinrichsen

    1991-01-01

    Jute fibers were investigated to verify their possible application in reinforcement of thermoplastics. A laboratory press was modified and laminates were produced using polymer films of LDPE, HDPE, PE copolymer, and PP as interlayers. Variations of the processing parameters were carried out in order to find optimal adjustment. High molding temperature leads to a decrease of mechanical properties and water

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

    NASA Technical Reports Server (NTRS)

    Ward, Thomas C.

    2003-01-01

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

  11. 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.

  12. Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Gilwee, W. J., Jr.; Parker, J. A.

    1979-01-01

    The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated include polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated include epoxy, bismaleimide, a modified phenolic, and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass-reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented, and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

  13. 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.

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

    E-print Network

    Rubloff, Gary W.

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

  15. Suitability of thermoplastic polymer for the making of HV gas insulated substation insulator

    Microsoft Academic Search

    J.-L. Bessede; I. Huet; Y. Kieffel; H. Aeshbach; F. Braeuer; K. Pohlink; A. Dahoun; S. Etienne; J.-M. Hiver

    2005-01-01

    Nowadays, improving the recyclability of the high voltage apparatus is a main concern of the manufacturers. Within this problematic, the suitability of thermoplastic polymer used as support insulator in high voltage gas insulated substation is presented in this paper. Among the possible candidates, a semi-crystalline thermoplastic polyethyleneterephtalate was selected and investigated. To begin with, chemical structure and morphology as well

  16. High-performance substrate based on a highly filled thermoplastic polymer

    Microsoft Academic Search

    Thomas Apeldorn; F. Wolff-Fabris; V. Altstädt

    2011-01-01

    Purpose – The purpose of this paper is to investigate and present the properties of a new substrate material based on thermoplastic polymers (so-called LuVo Board) for high-frequency applications. Design\\/methodology\\/approach – The thermal, mechanical and electrical properties of a new thermoplastic substrate are investigated and compared to conventional substrates for printed circuit board (PCB) applications. Findings – The new LuVo

  17. 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.

  18. 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

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

    NASA Astrophysics Data System (ADS)

    Ganesan, Amirthan; Yamada, Motohiro; Fukumoto, Masahiro

    2013-12-01

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

  20. Spall fracture characterization of thermosetting and thermoplastic polymer matrix composite plates

    Microsoft Academic Search

    Nobuo Takeda; Haruo Komatsu; Kiyoshi Takahashi

    1993-01-01

    So-called spall fractures (through-the-thickness tensile impact fractures) in simple uniaxial strain were examined for typical glass fiber reinforced thermosetting and thermoplastic polymer composite plates. An exploding foil technique was used to accelerate thin flyer plates towards composite plates to generate spall fractures. For thermosetting polyester composites, different fiber surface treatments were applied to study the effects of interfacial strengths on

  1. 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

    2015-06-01

    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

  2. Thermodynamics of Water Sorption in High Performance Glassy Thermoplastic Polymers

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 fro 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 poymers as well as for mean field and for hydrogen bonding interactions, providing a satisfactory quantitative interpretation of the experimental data.

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

    SciTech Connect

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

    2012-01-01

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

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

    Microsoft Academic Search

    D M Hoffman; A L Shields

    2009-01-01

    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

  5. Strategies for the synthesis of thermoplastic polymer nanocomposite materials with high inorganic filling fraction.

    PubMed

    Ojha, Satyajeet; Dang, Alei; Hui, Chin Ming; Mahoney, Clare; Matyjaszewski, Krzysztof; Bockstaller, Michael R

    2013-07-16

    The governing parameters controlling the miscibility of particle additives within polymeric host media are analyzed for the particular case of silica particle fillers embedded within a poly(methyl methacrylate) (PMMA) matrix. For athermal polymer-graft modification of particles (corresponding to equal chemical composition of graft and matrix polymer), compatibility is found to be a sensitive function of the degree of polymerization of graft and host polymer chains as well as the particle radius. In agreement with theoretical predictions, uniform particle dispersion is observed if the degree of polymerization of grafted chains is comparable to (or exceeds) the corresponding value of the polymer matrix. The resulting restriction to high degree of polymerization limits the accessible inorganic fraction that is attainable in athermal particle/polymer blends. In contrast, favorable interaction between grafted polymer chains and the polymeric host (as realized in the case of poly(styrene-r-acrylonitrile)-grafted particles embedded within PMMA matrix) is shown to facilitate thermodynamically stable and uniform particle dispersion across the entire compositional range even in the limit of large particle size, short grafted chains, and high molecular matrix chains. The synthesis of thermoplastic composite materials with inorganic fraction exceeding 50 vol % combining quantitative optical limiting within the UV frequency range and polymer-like mechanical properties is demonstrated. PMID:23786358

  6. 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.

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

    SciTech Connect

    Colton, J.S. [Georgia Inst. of Technology, Atlanta, GA (United States)

    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.

  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. Modeling morphology evolution during injection molding of thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Pantani, R.; De Santis, F.; Speranza, V.; Titomanlio, G.

    2015-05-01

    The effect of temperature, pressure and flow on relaxation time (or spectrum), crystallization time, nucleation density and rate, spherulite growth rate, the interrelation among these quantities and the distributions of deformation rate and cooling time during the process all together determine the morphology distribution in the final object. A simple model linking all these quantities was developed to describe morphology evolution during polymer processing. The effect of flow on nucleation density and growth rate of an isotactic polypropylene (iPP) is described on the basis of a molecular stretch parameter and the stretch evolution is described by a simple nonlinear Maxwell model, whose relaxation time, in its turn, is determined by the molecular stretch and, obviously, temperature pressure and crystallinity [1]. The model is applied to the description of morphology evolution during the injection molding process of a very accurately characterized iPP as far as rheology, quiescent crystallization and effect of flow on nucleation and spherulitic growth rates. Main characteristics of final morphology are reproduced by the simulations.

  10. Shear strength of polymers and fibre composites: 1. thermoplastic and thermoset polymers

    Microsoft Academic Search

    K. Liu; M. R. Piggott

    1995-01-01

    The shear strengths of eight thermoplastics and three DGEBA-based epoxies in sheet form have been tested by the punch and Iosipescu tests. The testing temperatures ranged from 20 to 120°C, and the glass transition temperatures were measured as well. The shear strengths of the epoxies were also estimated from compressive tests on short cylinders. The Iosipescu test gave very unreliable

  11. The photochromic properties of indoline spirooxazine-thermoplastic polymer systems obtained by supercritical fluid impregnation

    NASA Astrophysics Data System (ADS)

    Glagolev, N. N.; Solov'eva, A. B.; Kotova, A. V.; Shashkova, V. T.; Zapadinskii, B. I.; Zaichenko, N. L.; Kol'Tsova, L. S.; Shienok, A. I.; Timashev, P. S.; Bagratashvili, V. N.

    2009-05-01

    The impregnation of thermoplastic polymers (polyethylene, polypropylene, polymethyl methacrylate, and polycarbonate) with photochromic compounds from the class of indoline spirooxazines in supercritical carbon dioxide (SC-CO2) was studied. The concentration of the photochrome and the kinetics of decolorization of its colored form depended strongly on the type of the polymer matrix and the structure of spirooxazine. The introduction of 1,3',3'-trimethylspiro(indoline-2',3-3H-anthraceno[2,1-b][1,4]oxazine) (SAO) into polycarbonate caused anomalous stabilization (the prolonged conservation of the excited colored form of SAO in the polymer matrix). In contrast to other photochrome-polymer pairs, after supercritical impregnation into polycarbonate, at least 10% of all SAO molecules were in the colored form, which was highly stable and did not decolorize after 150 days; the rest of the impregnated SAO molecules were localized in the matrix as individual molecules, partially colorized after matrix relaxation, or nanocrystals of characteristic sizes ˜10-20 nm. The mechanisms of the anomalous stabilization of the colored SAO form in the polycarbonate matrix are discussed.

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

    PubMed Central

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

    2006-01-01

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

  13. 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

  14. 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

  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. Reactive Processing of Polymers: A) Reactive Processing of Engineering Thermoplastics; B) Reaction Injection Molding of Polyurethanes

    Microsoft Academic Search

    H. G. Schmelzer; R. J. Kumpf

    1997-01-01

    As a class of materials, engineering thermoplastics have enjoyed phenomenal growth in sales. The capital investment required to develop and introduce a new engineering thermoplastic has, however, increased dramatically. In response to these competitive pressures, engineering resin producers have increasingly focused their R&D efforts towards improving the performance of existing resins. One approach is to move chemistry from reaction vessels

  17. 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; da Silva, Guilherme Ferreira; Tanomaru Filho, Mário

    2015-03-01

    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

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

    NASA Astrophysics Data System (ADS)

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

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

  19. Rapid fabrication of thermoplastic polymer refractive microlens array using contactless hot embossing technology.

    PubMed

    Xie, Dan; Chang, Xuefeng; Shu, Xiayun; Wang, Yingchun; Ding, Huanqi; Liu, Yangxu

    2015-02-23

    A thermoplastic polymer refractive microlens array has been rapidly fabricated by contactless hot embossing technology through the stainless steel template with micro through-holes array, which has a diameter of 150 µm and a pitch of 185 µm. By optimizing the technical parameters including heating and demoulding temperature, loading pressure, loading and pressure holding time, a series of high quality microlenses arrays of different sags could be obtained. In addition, the sag and the radius of curvature of the microlens are controllable. The geometrical and optical properties of the microlenses are measured and the influence of temperature and pressure duration on the optical properties of the microlenses are analysed. The results show good surface features and optical performances. Unlike previous contactless hot embossing, a low cost and durable stainless steel template was utilized instead of silicon or nickel mold to avoid valuable equipments and complicated fabrication procedure. Besides, the whole contactless hot embossing process was absence of vacuum equipment. We think that the technology could be an attractive high flexibility method for enhancing efficiency and reducing cost. PMID:25836549

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

    SciTech Connect

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

    2014-06-10

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

  1. Electron microprobe analysis as a novel technique to study the interface between thermoset and thermoplastic polymers

    Microsoft Academic Search

    Hideko T Oyama; T. N Solberg; J. P Wightman

    1999-01-01

    Bilayer films between thermoset epoxy and thermoplastic poly(vinylpyrrolidone) (PVP) were prepared by casting a stoichiometric mixture of the uncured diglycidyl ether of bisphenol A epoxy (DGEBA) and 4,4?-diaminodiphenylsulfone (DDS) on a PVP film and then curing the system in a two-step process under an inert gas atmosphere. The resultant interface was analyzed by electron microprobe analysis (EMP). The EMP results

  2. Polymer blends based on an epoxy-amine thermoset and a thermoplastic

    Microsoft Academic Search

    J. López; M. Rico; B. Montero; J. Díez; Carmen Ramírez

    2009-01-01

    The effect of thermoplastic modification of an epoxy-amine system on the cure reaction, miscibility and thermal stability\\u000a of the system was investigated. The cure kinetics showed an autocatalytic behavior. Modifier did not affect either the total\\u000a reaction heat or the achieved maximum conversion but delayed the kinetics. The model of Horie-Kamal corrected by diffusion\\u000a factor was used to adjust kinetics

  3. Melt Mixing as Method to Disperse Carbon Nanotubes into Thermoplastic Polymers

    Microsoft Academic Search

    Petra Pötschke; Arup R. Bhattacharyya; Andreas Janke; Sven Pegel; Albrecht Leonhardt; Christine Täschner; Manfred Ritschel; Siegmar Roth; Björn Hornbostel; Jiri Cech

    2005-01-01

    This paper presents melt mixed composites where two ways of introducing nanotubes in polymer matrices were used. In the first case, commercially available masterbatches of nanotube\\/polymer composites are used as the starting materials that are diluted by the pure polymer in a subsequent melt mixing process (masterbatch dilution method) while in the other case nanotubes are directly incorporated into the

  4. MECHANICAL AND ELECTRICAL PROPERTIES OF THERMOPLASTIC STARCH COMPOSITES USING CARBON BLACK AS A CONDUCTIVE FILLER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermoplastic starch was blended with carbon black to form an electroactive polymer composite. Thermoplastic starch is naturally insulative, and the electroactive polymer composite takes advantage of the conductive pathways formed through the percolation of conductive particles through the polymer ...

  5. Melt-electrospinning of thermoplastic polymers: An experimental and theoretical analysis

    Microsoft Academic Search

    Jason Michael Lyons

    2004-01-01

    Over the past decade, there have been significant advancements in the area of electrospinning. A variety of polymers are being electrospun to form fibers on the nanoscale believed to have mechanical properties superior to those commercially available. Past research has focused on forming these fibers from a polymer solution but ever increasing demands for a cheaper, more environmentally friendly and

  6. Preparation of Thermoplastic X-ray Masks for Medical Applications

    Microsoft Academic Search

    Jindarat Pimsamarn

    The objective of this thesis was to study the appropriate polymer for preparation of thermoplastic masks for medical applications. The commercial thermoplastic mask was characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The results indicated that the type of polymer being used is polycaprolactone. The tensile strength, hardness and impact strength of the commercial thermoplastic mask

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

    NASA Astrophysics Data System (ADS)

    Raghavendra, Venkat Krishna

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

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

    E-print Network

    Ibrahim, Sarah H

    2005-01-01

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

  9. 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 considering time dependent material behavior.

  10. An overview of long fiber reinforced thermoplastics

    SciTech Connect

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

    1995-12-01

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

  11. 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...

  12. Highlights in these programmes are: i vacuum consolidation of thermoplastic

    E-print Network

    thermoplastic polymer matrix composites (PMCs) and associated process technologies. The aim is to improve, producing a laminate of high quali- ty and low porosity and, finally, it protects the polymer from

  13. 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.

  14. Ionic liquids as additives for thermoplastics

    Microsoft Academic Search

    K. I. Park; M. Xanthos

    2007-01-01

    In attempts to develop new process modifiers for thermoplastics, two ionic liquids with long chain hydrophobic cations and different anions were introduced in a biodegradable polymer. Methods of incorporation included melt blending, solvent casting and microencapsulation from w\\/o\\/w systems at concentrations up to 10 wt%. The modified polymers were characterized rheologically and by TGA to determine process and thermal stability,

  15. 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.

  16. 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

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

    PubMed

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

    2014-02-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  19. BAR 1095 and BAK 2195: completely biodegradable synthetic thermoplastics

    Microsoft Academic Search

    E. Grigat; R. Koch; R. Timmermann

    1998-01-01

    BAK-type polyesteramides are new polymers. The combination of high technical performance and full biodegradability is significant for this new generation of thermoplastic materials. All thermoplastic processes such as extrusion, film blowing, film casting, injection molding, blow molding, fiber spinning and others open a wide field of applications.

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

    Microsoft Academic Search

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

    2007-01-01

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

  1. An overview of long fiber reinforced thermoplastics

    SciTech Connect

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

    1997-12-31

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

  2. Long carbon fiber thermoplastics for injection molding

    SciTech Connect

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

    1993-12-31

    Thermoplastic composite materials have been under intense evaluation for the past decade in a variety of applications. Engineering polymers reinforced with long (12 mm) carbon fiber are a class of materials that provide easy processing and performance benefits between that of continuous and chopped carbon fiber reinforced materials. Commercially available materials include polyamide 66, polyphenylene sulfide and thermoplastic polyurethanes. Injection molding of these materials permits the fabrication of complex shapes that retain fiber length and have performance intermediate to that of chopped and continuous carbon fiber reinforced materials. Performance characteristics, processing costs and applications will be discussed.

  3. NOVEL THERMOPLASTIC ELASTOMERS FOR UNIVERSAL OVERMOLDING ON DISSIMILAR THERMOPLASTICS

    Microsoft Academic Search

    Liang Xu; Sehyun Kim; Rajesh Varma; Krishna Venkataswamy

    Overmolding thermoplastic elastomers (TPEs) onto rigid thermoplastics has been an explosive trend in the last decade. Thermoplastics are used in various applications, including PP, PS, ABS, copolyester, SAN, PC etc.. Recently, many TPEs have been uniquely developed to bond to specific substrate materials based on surface energy or polarity match between the elastomer and the thermoplastics. However, these TPEs are

  4. Modelling of the viscoelastic behaviour of amorphous thermoplastic\\/glass beads composites based on the evaluation of the complex Poisson's ratio of the polymer matrix

    Microsoft Academic Search

    A. Agbossou; A. Bergeret; K. Benzarti; N. Alberola

    1993-01-01

    A series of polystyrene\\/glass beads composites were studied by using dynamic mechanical spectrometry. From experimental data obtained under isothermal conditions, a simulation method of viscoelastic behaviour of amorphous thermoplastics reinforced by glass beads was devised. Such a theoretical approach confirmed the requirement of considering the Poisson's ratio as a complex component over all the temperature range. This could be related

  5. An investigation of physical properties of thermoplastic polyimides

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Stoakley, Diane M.

    1987-01-01

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

  6. Processing of wood-thermoplastic composites

    Microsoft Academic Search

    Mladen Šercer; Pero Raos; Maja Rujni?-Sokele

    2009-01-01

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

  7. 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.

  8. Modeling of temperature distribution in ultrasonic welding of thermoplastics for various joint designs

    Microsoft Academic Search

    K. S. Suresh; M. Roopa Rani; K. Prakasan; R. Rudramoorthy

    2007-01-01

    Use of engineering plastics in structural and non-structural applications is rapidly increasing. As the demand for plastics increases so does the requirements for joining. Of the many techniques that are available for joining of thermoplastics, ultrasonic welding is one of the preferred processes. Thermoplastic polymers are categorized according to their molecular structure as amorphous and semi-crystalline. Ultrasonic welding of these

  9. 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.

  10. 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.

  11. Materials selection and manufacturing of thermoplastic elastomer microfluidics

    NASA Astrophysics Data System (ADS)

    Sameoto, D.; Wasay, A.

    2015-03-01

    In this paper we outline some of the manufacturing advantages and challenges of working with thermoplastic elastomers as an alternative to traditional polydimethysiloxane (PDMS) for flexible and reversibly bonded microfluidic systems. Unlike PDMS, thermoplastic elastomers can be processed with many industrial polymer manufacturing technologies such as extrusion, injection molding, hot embossing and others, potentially permitting much more scalable production and cheaper costs per part. Unlike a more rigid thermoplastic, these thermoplastic elastomers are typically much easier to bond, either reversibly or permanently due to their inherent compliance and subsequent low pressures necessary to seal channels and reservoirs. Unlike PDMS however, where one material (Sylgard 184) dominates the literature, there have not been many in depth investigations into thermoplastic elastomers and their relative performance and applicability to microfabrication. We show a comparison between several categories of thermoplastic elastomer to demonstrate what issues may be encountered and to demonstrate that even for labs with minimal equipment, academic prototyping with these materials is not necessarily any more challenging than PDMS.

  12. Fully integrated single-walled carbon nanotube thermoplastic composites

    Microsoft Academic Search

    Fernando J. Rodriguez-Macias

    2004-01-01

    The development of composites of single-walled carbon nanotubes (SWNTs) with thermoplastics requires methods for good dispersion and achieving good interaction between SWNTs and the matrix. This thesis presents a new method to achieve good dispersion by a preliminary treatment called incipient wetting. The SWNTs dispersed in a solvent are mixed with polymer particles and deposited over them as the solvent

  13. 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%) ...

  14. Selection of the spraying technologies for over-coating of metal-stampings with thermoplastics for use in direct-adhesion polymer metal hybrid load-bearing components

    Microsoft Academic Search

    M. Grujicic; V. Sellappan; L. Mears; X. Xuan; Norbert Seyr; Marc Erdmann; Jochen Holzleitner

    2008-01-01

    The suitability of various polymer-powder spraying technologies for coating of metal-stampings used in polymer metal hybrid (PMH) load-bearing automotive-component applications is considered. The suitability of the spraying technologies is assessed with respect to a need for metal-stamping surface preparation\\/treatment, their ability to deposit the polymeric material without significant material degradation, the ability to selectively overcoat the metal-stamping, the resulting magnitude

  15. Laser beam welding of thermoplastics

    NASA Astrophysics Data System (ADS)

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

    2003-07-01

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

  16. Thermoplastic Waves in Magnetars

    NASA Astrophysics Data System (ADS)

    Beloborodov, Andrei M.; Levin, Yuri

    2014-10-01

    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.

  17. 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.

  18. Phase Separation of Liquid Crystals in Polymers

    Microsoft Academic Search

    John L. West

    1988-01-01

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

  19. Close Encounters of the Polymer Kind

    NSDL National Science Digital Library

    2014-09-18

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

  20. 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.

  1. 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 not always produce better feature replication, suggesting that cooling effects in the tooling "holes" restricted filling. High pressures also produced surface porosity in the molded pillars. Although thermoplastic vulcanizates, thermoplastic elastomers with excellent processability and flexibility, are a widely used for over molding and automotive applications, the third section of this research was the first in-depth investigation of injection molding thermoplastic vulcanizates to create microstructured surfaces. In this study, nickel cobalt tooling was used to mold commercially-available thermoplastic vulcanizates with polypropylene/ethylene propylene diene monomer (PP/EPDM) backbones into 20-mum-diameter and 100-mum-wide features. These results were compared to those for a polypropylene homopolymer. The primary molding parameters, including melt and mold temperatures were evaluated for their effects on microfeature replication. Additionally, a two-level, three-factorial design of experiments was conducted to further evaluate the effects of key parameters (cooling time, hold pressure, and polymeric material) on the feature definition and depth ratios of the molded microfeatures. These results were compared to the properties of the thermoplastic vulcanizates.

  2. Degradation Studies of Polycaprolactone in Banana Fibers Reinforced Thermoplastics Composites

    Microsoft Academic Search

    Sandeep Kumar; Indra K. Varma

    2006-01-01

    In this paper we report the fabrication, properties and degradation studies of banana fibers–reinforced thermoplastic polymers. In order to impart hydrophobicity to the fibers and also to concomitantly increase interfacial bond strength, which is a critical factor for obtaining better mechanical properties of composites, banana fibers were treated with sodium hydroxide (5% and 10% for 4 h), sebacoyl chloride (SC) (0.5 g,

  3. 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.

  4. Graft polymerization of native chicken feathers for thermoplastic applications.

    PubMed

    Jin, Enqi; Reddy, Narendra; Zhu, Zhifeng; Yang, Yiqi

    2011-03-01

    Inexpensive and biodegradable thermoplastics were developed through graft polymerization of native chicken feather with methyl acrylate as a potential substitute for petroleum products. Poultry feathers are available in large quantities at a low price. However, natural chicken feathers have poor thermoplasticity, cannot be used to develop thermoplastic products, have very limited industrial applications, and are often considered as solid wastes. In this research, the effects of graft polymerization conditions, such as molar ratio of NaHSO(3) to K(2)S(2)O(8), initiator and monomer concentrations, pH, temperature and time of polymerization, on grafting parameters, that is, the conversion of monomer to polymer, grafting percentage, and grafting efficiency were evaluated. Methyl acrylate was found to be successfully grafted onto functional groups on the surfaces of the chicken feathers, and optimal graft polymerization conditions were also obtained. The feather-g-poly(methyl acrylate) developed showed good thermoplasticity, and feather films had substantially higher tensile properties than soy protein isolate and starch acetate films. PMID:21302951

  5. High-pressure on-chip mechanical valves for thermoplastic microfluidic devices.

    PubMed

    Chen, Chien-Fu; Liu, Jikun; Chang, Chien-Cheng; DeVoe, Don L

    2009-12-21

    A facile method enabling the integration of elastomeric valves into rigid thermoplastic microfluidic chips is described. The valves employ discrete plugs of elastomeric polydimethylsiloxane (PDMS) integrated into the thermoplastic substrate and actuated using a threaded stainless steel needle. The fabrication process takes advantage of poly(ethylene glycol) (PEG) as a sacrificial molding material to isolate the PDMS regions from the thermoplastic flow channels, while yielding smooth contact surfaces with the PDMS valve seats. The valves introduce minimal dead volumes, and provide a simple mechanical means to achieve reproducible proportional valving within thermoplastic microfluidic systems. Burst pressure tests reveal that the valves can withstand pressures above 12 MPa over repeated open/close cycles without leakage, and above 24 MPa during a single use, making the technology well suited for applications such as high performance liquid chromatography. Proportional valve operation is demonstrated using a multi-valve chemical gradient generator fabricated in cyclic olefin polymer. PMID:20024030

  6. 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.

  7. 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.

  8. Novel Thermoplastic Elastomers with Universal Bonding Characteristics

    Microsoft Academic Search

    Liang Xu; Sehyun Kim; Krishna Venkataswamy; John Simons

    Overmolding thermoplastic elastomers (TPEs) on rigid substrates for consumer applications has been driven by the escalating market trends in enhanced ergonomic feel and touch, grip ability, aesthetics, cushioning against impact, vibration isolation and insulation. Polarity of the substrate dictates the chemical nature of the thermoplastic elastomer and hence the properties and the performance of the thermoplastic elastomer. This paper introduces

  9. Structure and thermoplasticity of coal

    SciTech Connect

    Komaki, I.; Itagaki, S.; Miura, T. (eds.)

    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.

  10. Micropump manufactured by thermoplastic molding

    Microsoft Academic Search

    B. Bustgens; W. Bacher; W. Menz; W. K. Schomburg

    1994-01-01

    A micromembrane pump was manufactured by combined thermoplastic molding and membrane techniques. Pump cases were made of polyvinylidene fluoride (PVDF) and polysulfone (PSU). The mold insert was milled from a brass substrate. The lateral dimensions of the complete pump are 7 mm×10 mm. The depth and the diameter of the pump chamber are 100 ?m and 4 mm, respectively. The

  11. Fully integrated single-walled carbon nanotube thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Rodriguez-Macias, Fernando J.

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

  12. Effect of Concentration of Mica on Properties of Polyester Thermoplastic Elastomer Composites

    Microsoft Academic Search

    M. S. Sreekanth; V. A. Bambole; S. T. Mhaske; P. A. Mahanwar

    Particulate filled polymer composites are becoming attractive because of their wide applications and low cost. In this study the effects of mica with varying concentration on the mechanical, thermal, electrical, rheological and morphological properties of polyester thermoplastic elastomer (Hytrel ®) was investigated. Composites of Hytrel ® with varying concentrations (viz. 5 to 40 weight %) of mica were prepared by

  13. Advances in thermoplastic matrix composite materials

    SciTech Connect

    Newaz, G.M.

    1989-01-01

    Accounts are given of the development status of thermoplastic composite processing methods, as well as their current thermal and mechanical behavior and delamination properties. Attention is given to the thermoplastic coating of carbon fibers, pultrusion-process modeling, the high temperature behavior of graphite/PEEK, the thermal conductivity of composites for electronic packaging, a FEM analysis of mode I and II thermoplastic-matrix specimens, and reinforcements' resin-impregnation behavior during thermoplastic composite manufacture. Also discussed are the mechanical properties of carbon fiber/PEEK for structural applications, moisture-content mechanical property effects in PPS-matrix composites, the interlaminar fracture toughness of thermoplastic composites, and thermoplastic composite delamination growth under elevated temperature cyclic loading.

  14. 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.

  15. Valveless diffuser micropumps fabricated using thermoplastic replication

    Microsoft Academic Search

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

    1998-01-01

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

  16. Valveless diffuser micropumps fabricated using thermoplastic replication

    Microsoft Academic Search

    Anders Olsson; Olle Larsson; Johan Holm; Lars Lundbladh; Ove Ohman; Goran Stemme

    1997-01-01

    Here we present the first valve-less diffuser micropumps fabricated using thermoplastic replication. Due to its simple planar geometry the valve-less diffuser pump is very suitable for thermoplastic replication. Two different thermoplastic replication methods have been used: hot embossing and injection molding. As mold inserts we used 0.1 and 0.2 mm deep precision milled brass mold inserts and 20 and 80

  17. Laser transmission welding of optical transparent thermoplastics

    NASA Astrophysics Data System (ADS)

    Devrient, M.; Frick, T.; Schmidt, M.

    Laser transmission welding is a well known joining technology for thermoplastics. As undoped thermoplastics have a low absorption for electro-magnetic radiation with wave lengths from 350 nm till 1,400 nm absorbers are used for laser transmission welding. One disadvantage may be the unmeant colouration which occurs when thermoplastics are doped with absorbers. Therefore an approach to weld transparent thermoplastics by the use of common diode lasers but without absorbers is presented. The developed system technology is introduced and results of welding experiments as well as results achieved by process simulation with a finite element model are shown.

  18. 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.

  19. 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

  20. 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.

  1. Improved Thermoplastic/Iron-Particle Transformer Cores

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    A method of fabricating improved transformer cores from composites of thermoplastic matrices and iron-particles has been invented. Relative to commercially available laminated-iron-alloy transformer cores, the cores fabricated by this method weigh less and are less expensive. Relative to prior polymer-matrix/ iron-particle composite-material transformer cores, the cores fabricated by this method can be made mechanically stronger and more magnetically permeable. In addition, whereas some prior cores have exhibited significant eddy-current losses, the cores fabricated by this method exhibit very small eddy-current losses. The cores made by this method can be expected to be attractive for use in diverse applications, including high-signal-to-noise transformers, stepping motors, and high-frequency ignition coils. The present method is a product of an experimental study of the relationships among fabrication conditions, final densities of iron particles, and mechanical and electromagnetic properties of fabricated cores. Among the fabrication conditions investigated were molding pressures (83, 104, and 131 MPa), and molding temperatures (250, 300, and 350 C). Each block of core material was made by uniaxial-compression molding, at the applicable pressure/temperature combination, of a mixture of 2 weight percent of LaRC (or equivalent high-temperature soluble thermoplastic adhesive) with 98 weight percent of approximately spherical iron particles having diameters in the micron range. Each molded block was cut into square cross-section rods that were used as core specimens in mechanical and electromagnetic tests. Some of the core specimens were annealed at 900 C and cooled slowly before testing. For comparison, a low-carbon-steel core was also tested. The results of the tests showed that density, hardness, and rupture strength generally increased with molding pressure and temperature, though the correlation was rather weak. The weakness of the correlation was attributed to the pores in the specimens. The maximum relative permeabilities of cores made without annealing ranged from 30 to 110, while those of cores made with annealing ranged from 900 to 1,400. However, the greater permeabilities of the annealed specimens were not associated with noticeably greater densities. The major practical result of the investigation was the discovery of an optimum distribution of iron-particle sizes: It was found that eddy-current losses in the molded cores were minimized by using 100 mesh (corresponding to particles with diameters less than or equal to 100 m) iron particles. The effect of optimization of particle sizes on eddy-current losses is depicted in the figure.

  2. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    Thermomechanical properties, flammability, oxygen index, relative toxicity of pyrolysis effluents, and char yields were studied for 12 advanced polymers which are candidates for use in aircraft interiors as decorative films, compression- and injection-molded parts and thermoplastic parts. Polymers sampled included polyphenylene sulfide, 9,9 bis (4-hydroxyphenol) fluorene polycarbonate-poly (dimethylsiloxane), polyether sulfone, polyvinyl fluoride and polyvinylidene fluoride. Availability of these samples, whether in commercial form or in test quantities, is specified. An estimate of relative fire resistance for the materials was obtained; the five polymers listed above were found to be the most fire resistant of the 12 sampled.

  4. Joining of thermoplastic substrates by microwaves

    DOEpatents

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

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wang, Dong

    In situ fibrillar and lamellar hybrid morphology was found in various immiscible polymer blends prepared by melt ram extrusion of cellulose acetate butyrate (CAB)/Thermoplastics at a weight ratio of 80 to 20. The formation process was analyzed and proposed. The presence of the elongational flow field determines the formation of the fibrils, and the improvement of the mixing efficiency can significantly reduce the dimensions of formed fibrils into the submicro- or nano-scale. With above results, continuous and uniform yarns of thermoplastic nanofibers were prepared via direct melt twin-screw extrusion, providing better mixing efficiency of immiscible blends of thermoplastic polymers with cellulose acetate butyrate (CAB), and subsequent extraction removal of CAB matrix. The thermoplastics which can be made into nanofibers include polyesters, polyolefins, thermoplastic polyurethane and functional copolymers, such as PE-co-GMA (Poly(Ethylene-co-Glycidyl Methacrylate)), PVA-co-PE (Poly(Vinyl Alcohol-co-Ethylene)). Ratios of thermoplastics to sacrificial CAB matrix, melt viscosity, and interfacial tensions affect formation of the nanofibers. Moreover, the crystal structures of isotactic polypropylene (iPP) nanofiber prepared were characterized with DSC and WAXD. To further demonstrate the size and shape controllability of the thermoplastic nanomaterials, polyethylene materials were selected and prepared into micro- or submicrospheres or nanofibers with different diameters and shapes by varying the composition ratio and modifying the interface properties via melt blending or extrusion of cellulose acetate butyrate (CAB)/LDPE melt blends and subsequent removal of the CAB. The surface structures of the LDPE micro- or submicrospheres and nanofibers were analyzed using SEM, FTIR-ATR spectroscopy, DSC and torque rheometer. The biotechnological applications of the thermoplastic nanofibers are also exploited. Poly(ethylene-co-glycidyl methacrylate) (PE-co-GMA) nanofibers with abundant active epoxy groups on surfaces were fabricated through above technique. The prepared PE-co-GMA nanofibers were aminated by reacting the epoxy groups with 1,3-diaminopropane. The resulting aminated PE-co-GMA nanofibers were subsequently biotinylated and then successfully applied to immobilize streptavidin-horseradish peroxidase (HRP) conjugate via specific, strong and rapid binding of biotin and streptavidin. The high activity, efficiency, sensitivity as well as good reusability of the streptavidin-HRP immobilized PE-co-GMA nanofibers demonstrated that PE-co-GMA nanofibers could be a promising candidate as solid support materials for potential biosensor applications.

  6. 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)

  7. Thermoplastic rubberlike material produced at low cost

    NASA Technical Reports Server (NTRS)

    Hendel, F. J.

    1966-01-01

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

  8. Thermoplastic matrix composite processing model

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  9. Conductive network formation in the melt of carbon nanotube\\/thermoplastic polyurethane composite

    Microsoft Academic Search

    Rui Zhang; Alice Dowden; Hua Deng; Mark Baxendale; Ton Peijs

    2009-01-01

    This research concerns the effect of conductive network formation in a polymer melt on the conductivity of multi-walled carbon nanotube\\/thermoplastic polyurethane composite systems. An extremely low percolation threshold of 0.13wt.% was achieved in hot-pressed composite film samples, whereas a much higher CNT concentration (3–4wt.%) is needed to form a conductive network in extruded composite strands. This is explained in terms

  10. 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.

  11. Thermoplastic starch processing and characteristics-a review.

    PubMed

    Zhang, Yachuan; Rempel, Curtis; Liu, Qiang

    2014-01-01

    Canola Council of Canada, Winnipeg, Manitoba, Canada The rising costs of nonrenewable feedstocks and environmental concerns with their industrial usage have encouraged the study and development of renewable products, including thermoplastic starch (TPS). Starch is an abundant, plant-based biodegradable material with interesting physicochemical characteristics that can be exploited, and this has received attention for development of TPS products. Starch exhibits usable thermoplastic properties when plasticizers, elevated temperatures, and shear are present. The choice of plasticizer has an effect on TPS, even when these have similar plasticization principles. Most TPS have glass transition temperature, Tg, in the range of approximately -75 to 10°C. Glassy transition of TPS is detected by differential scanning calorimeter (DSC) and thermodynamic analyzer (DMA), although DMA has been found to be more sensitive and effective. TPS has low tensile properties, typically below 6 MPa in tensile strength (TS). The addition of synthetic polymers, nanoclay, and fiber can improve TS and water-resistance ability. The moisture sorption behavior of TPS is described in GAB and BET models, from which monolayer moisture content and specific area are derived. Current studies on surface tension, gas permeability, crystallinity, and so on of the TPS are also reviewed. PMID:24564592

  12. 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.

  13. 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 by reactive coupling. In the first work, the unique interfacial reactions were applied to promote TPU-PP adhesion that was quantified by asymmetric double cantilever beam test. In the second study, the abnormally high flow activation energy of TPU was explained by simultaneously investigating the effect of temperature and thermal degradation on the melt viscosity. In the third project, block copolymers were prepared by rapid reactive coupling of amine and isocyanate functional polymers and the reaction kinetics were also studied.

  14. 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

  15. Microcellular Foams Based on High Performance Thermoplastic Nanocomposites

    SciTech Connect

    Sorrentino, Luigi; Iannace, Salvatore [Institute for Composite and Biomedical Materials-National Research Council Piazzale V. Tecchio, 80-80125 Napoli (Italy)] [IMAST-Technological District in Polymer and Composite Engineering P.le Fermi 1 80055 Portici (Italy); Gargiulo, Marcella [Institute for Composite and Biomedical Materials-National Research Council Piazzale V. Tecchio, 80-80125 Napoli (Italy); Pezzullo, Giuseppe [Department of Materials and Production Engineering-University of Napoli Federico II Piazzale V. Tecchio, 80-80125 Napoli (Italy)

    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.

  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. Plastic wastes as modifiers of the thermoplasticity of coal

    SciTech Connect

    M.A. Diez; C. Barriocanal; R. Alvarez [Instituto Nacional del Carbon (INCAR), Oviedo (Spain)

    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.

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

    PubMed

    Taghizadeh, Ata; Favis, Basil D

    2013-10-15

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

  19. A Study on New Composite Thermoplastic Propellant

    NASA Astrophysics Data System (ADS)

    Kahara, Takehiro; Nakayama, Masanobu; Hasegawa, Hiroshi; Katoh, Kazushige; Miyazaki, Shigehumi; Maruizumi, Haruki; Hori, Keiichi; Morita, Yasuhiro; Akiba, Ryojiro

    Efforts have been paid to realize a new composite propellant using thermoplastics as a fuel binder and lithium as a metallic fuel. Thermoplastics binder makes it possible the storage of solid propellant in small blocks and to provide propellants blocks into rocket motor case at a quantity needed just before use, which enables the production facility of solid propellant at a minimum level, thus, production cost significantly lower. Lithium has been a candidate for a metallic fuel for the ammonium perchlorate based composite propellants owing to its capability to reduce the hydrogen chloride in the exhaust gas, however, never been used because lithium is not stable at room conditions and complex reaction products between oxygen, nitrogen, and water are formed at the surface of particles and even in the core. However, lithium particles whose surface shell structure is well controlled are rather stable and can be stored in thermoplastics for a long period. Evaluation of several organic thermoplastics whose melting temperatures are easily tractable was made from the standpoint of combustion characteristics, and it is shown that thermoplastics propellants can cover wide range of burning rate spectrum. Formation of well-defined surface shell of lithium particles and its kinetics are also discussed.

  20. 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.

  1. 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, ?, 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.

  2. Selecting thermoplastics for engineering applications. Second edition

    SciTech Connect

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

    1997-12-31

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

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated included polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated included epoxy, bismaleimide, a modified phenolic and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

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

    NASA Astrophysics Data System (ADS)

    Jamiyanaa, Khongor

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

  5. Using PDMS Micro-Transfer Moulding for Polymer Flip Chip Packaging on MEMS

    Microsoft Academic Search

    Edward K. L. Chan; C. K. Y. Wong; M. Lee; Matthew M. F. Yuen; Yi-Kuen Lee

    2005-01-01

    Polymer flip chip process utilizes Ag filled thermoset and\\/or thermoplastic polymers, in combination with stencil printing processes to form polymer bump interconnects of flip chip IC devices (Estes, 1998). Nevertheless, slumping behavior of conventional polymer interconnect material during bumping process on the wafer chip has constrained the bump height achieved by the most common stencil printing to 50mum (Kulesza et

  6. Polymer bonding process for nanolithography

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

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

  7. Synthetic organic fibers — reinforced thermoplastics I

    Microsoft Academic Search

    H. Käufer; E. M. Abdel-Bary

    1982-01-01

    The interfacial adhesion between fibers as reinforcing fillers and thermoplastic matrices is a key requirement for obtaining effective reinforcement. Therefore, in situ polymerization of styrene onto polyethyleneterephthalate and in situ bulk polymerization of the same monomer on aromatic polyamide (Kevlar-aramid) fibers were carried out. In both cases, divinyl benzene was used as crosslinking agent in order to ensure the presence

  8. Glass Fiber Length Degradation in Thermoplastics Rocessing

    Microsoft Academic Search

    Robert A. Schweizer

    1982-01-01

    Glass fiber length is of great concern to both the compounder and molder of fiberglass reinforced thermoplastics. We know that the fiber attrition is considerable, but how short is it and where in the process does it occur? Can it be affected by using the longer length chopped strands? These are the types of questions that have gone unanswered because

  9. Global weathering of aromatic engineering thermoplastics

    Microsoft Academic Search

    J. E. Pickett; M. M. Gardner; D. A. Gibson; S. T. Rice

    2005-01-01

    The rates of gloss loss and color shift for 24 aromatic engineering thermoplastics at nine exposure sites world-wide have been compared relative to a commercial Miami exposure site. The scatter among individual samples was large, but on average, light dose alone was enough to account for almost all of the rate differences among the various sites for these materials. Temperature,

  10. 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.

  11. Spatial frequency response of thermoplastic films

    Microsoft Academic Search

    D. S. Lo; L. H. Johnson; R. W. Honebrink

    1975-01-01

    The spatial frequency response is investigated using a multilayer device that consists of a PVK-TNF photoconductor layer, a polystyrene thermoplastic layer, and an InO transparent layer on a glass substrate. To determine the frequency response, the diffraction efficiency (ratio of the intensity of the light diffracted by the hologram during readout to the intensity of the readout light) is measured

  12. 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 ...

  13. Material fire properties and predictions for thermoplastics

    Microsoft Academic Search

    D. Hopkins; J. G. Quintiere

    1996-01-01

    Ignition and burning rate data are developed for nylon 6\\/6, polyethylene, polypropylene and black polycast PMMA in a cone calorimeter heating assembly. The objective is to examine a testing protocol that leads to the prediction of ignition and burning rate for thermoplastics from cone calorimeter data. The procedure consists of determining material properties, i.e. thermal inertia, specific heat, thermal conductivity,

  14. 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

  15. 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

  16. Surface tension, interfacial tension, and morphology in blends of thermoplastic polyurethanes and polyolefins. Part I. Surface tension of melts of TPU model substances and polyolefins

    Microsoft Academic Search

    Petra Pötschke; Jürgen Pionteck; Herbert Stutz

    2002-01-01

    The pendant drop analysis was used to determine surface tensions ? of polymer melts. For thermoplastic polyurethane (TPU) elastomers, which are block copolymers of crystallisable hard segments (HS) and amorphous soft segments (SS), the surface tensions of the different segments in the melt were measured for the first time. As model compounds for the SS polyetherdiols (PEt-diols) and a polyesterdiol

  17. 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.

  18. Processing Conjugated-Diene-Containing Polymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L.; Havens, Stephen J.

    1987-01-01

    Diels-Alder reaction used to cross-linked thermoplastics. Process uses Diels-Alder reaction to cross-link and/or extend conjugated-diene-containing polymers by reacting them with bis-unsaturated dienophiles results in improved polymer properties. Quantities of diene groups required for cross-linking varies from very low to very high concentrations. Process also used to extend, or build up molecular weights of, low-molecular-weight linear polymers with terminal conjugated dienic groups.

  19. Using synchrotron radiation to study polymer processing

    NASA Astrophysics Data System (ADS)

    Ryan, Anthony J.; Elwell, Michael J.; Bras, Wim

    1995-05-01

    Recent developments in time resolved X-ray scattering from polymers are reviewed in the context of structure development in polymer processing. The use of fast SAXS/WAXS and its combination with differential scanning calorimetry (DSC) is given as an example of the use of SR in studying thermoplastics processing. A second example of SR in polymer processing concerns the in situ measurement of structure development in polyurethane foam formed by reaction injection moulding.

  20. Temperature dependence of high strain-rate impact fracture behaviour in highly filled polymeric composite and plasticized thermoplastic propellants

    Microsoft Academic Search

    S. Y. Ho; C. W. Fong

    1987-01-01

    The effect of temperature and strain-rate on the fracture behaviour during high strain-rate (~ 103 sec-1) impact of two highly filled polymeric composite propellants (containing segmented polyurethanes based on hydroxy-term inated polybutadiene (HTPB) or glycidyl azide polymer (GAP) filled with ammonium perchlorate (AP) particles) and a plasticized thermoplastic (cast double base (CDB) nitrocellulose-nitroglycerine) propellant have been examined over a wide

  1. 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.

  2. Laser processing of glass fiber reinforced thermoplastics with different wavelengths and pulse durations

    NASA Astrophysics Data System (ADS)

    Schilling, N.; Krupop, B.; Klotzbach, U.

    2015-03-01

    In this paper, laser processing of fiber reinforced thermoplastics is investigated with different laser sources. Aim of the study is to determine the process windows in which selective ablation of polymer matrix and homogenous ablation of matrix and fiber occurs. To reach this, laser sources with different wavelengths (10600 nm, 1064 nm and 532 nm) and pulse durations in ?s, ns and ps regime are compared on their ablation behavior of natural and black colored glass fiber reinforced polypropylene. Best results were achieved with ns lasers with IR wavelength at black colored material. At this parameter combination a wide process window can be shown where no damage of the reinforcing fibers happens.

  3. Toughening of epoxies through thermoplastic crack bridging

    Microsoft Academic Search

    B. J. Cardwell; A. F. Yee

    1998-01-01

    The fracture toughness and toughening mechanism of two epoxy matrices containing varying concentrations of pre-formed polyamide-12 particles was investigated. The pre-formed thermoplastic modifier was used to keep the physical and morphological characteristics of the second phase constant while varying the matrix intrinsic toughness to simplify the interpretation of toughening results. We observed that these particles toughened the epoxies through a

  4. Challenges in Biomass–Thermoplastic Composites

    Microsoft Academic Search

    Roger M. Rowell

    2007-01-01

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

  5. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available thermoplastic based composite laminate is investigated followed by post processed part characterization. Key findings include an optimized composite processing window, and the influence of raw material blank forming temperature and mould tool temperature on part crystallinity and flexural strength. This process study forms one element of a major project structure which has been designed to address the gap between design, analysis and manufacturing, using at its core, a digital framework for the creation and management of performance parameters related to the lifecycle performance of thermoplastic composite structures.

  6. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

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

    2011-05-04

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available thermoplastic based composite laminate is investigated followed by post processed part characterization. Key findings include an optimized composite processing window, and the influence of raw material blank forming temperature and mould tool temperature on part crystallinity and flexural strength. This process study forms one element of a major project structure which has been designed to address the gap between design, analysis and manufacturing, using at its core, a digital framework for the creation and management of performance parameters related to the lifecycle performance of thermoplastic composite structures.

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

    Microsoft Academic Search

    Xuefeng Wang; Jonathan Engel; Chang Liu

    2003-01-01

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

  8. Stabilization for development of thermoplastic film in electron beam recording

    Microsoft Academic Search

    Takumi Minemoto; Toshiharu Nozawa; Yutaka Fukuda

    1981-01-01

    A method for stabilization in development of thermoplastic film is proposed. The method is applied to an electron beam recording system and its usefulness is confirmed experimentally. By using this method, the characteristic curve of a thermoplastic film is correctly measured and a one dimensional, first-order differentiation filter of the phase hologram type is made of the film.

  9. Thermal characterization of mica-filled thermoplastic polyurethane composites

    Microsoft Academic Search

    Dipak Baral; P. P De; Golok B Nando

    1999-01-01

    Thermoplastic polyurethane–mica composites were prepared in a Brabender Plasticorder at 180°C by melt mixing and their thermal properties were studied. The thermal stability of the thermoplastic polyurethane improved marginally on incorporation of mica, which shifted the decomposition temperature of the composite to a higher level, thus delaying the degradation. ©

  10. 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.

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

    SciTech Connect

    Devanathan, D.; King, R.; Swarts, D.; Lin, S. [Zimmer, Inc., Warsaw, IN (United States); Ramani, K.; Tagle, J. [Purdue Univ., West Lafayette, IN (United States). Dept. of Mechanical Engineering

    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

  12. 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.

  13. Multiblock thermoplastic polyurethanes for biomedical and shape memory applications

    NASA Astrophysics Data System (ADS)

    Gu, Xinzhu

    Polyurethanes are a class of polymers that are capable of tailoring the overall polymer structure and thus final properties by many factors. The great potential in tailoring polymer structures imparts PUs unique mechanical properties and good cytocompatibility, which make them good candidates for many biomedical devices. In this dissertation, three families of multiblock thermoplastic polyurethanes are synthesized and characterized for biomedical and shape memory applications. In the first case described in Chapters 2, 3 and 4, a novel family of multiblock thermoplastic polyurethanes consisting of poly(?-caprolactone) (PCL) and poly(ethylene glycol) (PEG) are presented. These materials were discovered to be very durable, with strain-to-break higher than 1200%. Heat-triggered reversible plasticity shape memory (RPSM) was observed, where the highly deformed samples completely recovered their as-cast shape within one minute when heating above the transition temperature. Instead of conventional "hard" blocks, entanglements, which result from high molecular weight, served as the physical crosslinks in this system, engendering shape recovery and preventing flow. Moreover, water-triggered shape memory effect of PCL-PEG TPUs is explored, wherein water permeated into the initially oriented PEG domains, causing rapid shape recovery toward the equilibrium shape upon contact with liquid water. The recovery behavior is found to be dependent on PEG weight percentage in the copolymers. By changing the material from bulk film to electrospun fibrous mat, recovery speed was greatly accelerated. The rate of water recovery was manipulated through structural variables, including thickness of bulk film and diameter of e-spun webs. A new, yet simple shape memory cycle, "wet-fixing" is also reported, where both the fixing and recovery ratios can be greatly improved. A detailed microstructural study on one particular composition is presented, revealing the evolution of microphase morphology during the shape memory cycle. Then, in Chapter 5, the role of Polyhedral oligosilsesquioxane (POSS) in suppressing enzymatic degradation of PCL-PEG TPUs is investigated. In vitro enzymatic hydrolytic biodegradation revealed that POSS incorporation significantly suppressed degradation of PCL-PEG TPUs. All TPUs were surface-eroded by enzymatic attack in which the chemical composition and the bulk mechanical properties exhibited little changes. A surface passivation mechanism is proposed to explain the protection of POSS-containing TPUs from enzymatic degradation. Finally, Chapter 6 presents another POSS-based TPUs system with PLA-based polyol as the glassy soft block. Manipulation of the final thermal and mechanical properties is discussed in terms of different polyols and POSS used. The free recovery and the constrained recovery responses of the polymer films were demonstrated as a function of the prior "fixing" deformation temperature. In addition, this family of materials was capable of memorizing their T g., where optimal recovery breadth and recovery stress were achieved when pre-deformation occurred right at Tg.

  14. Ductile thermoset polymers via controlling network flexibility.

    PubMed

    Hameed, N; Salim, N V; Walsh, T R; Wiggins, J S; Ajayan, P M; Fox, B L

    2015-06-01

    We report the design and synthesis of a polymer structure from a cross-linkable epoxy-ionic liquid system which behaves like a hard and brittle epoxy thermoset, perfectly ductile thermoplastic and an elastomer, all depending on controllable network compositions. PMID:26000341

  15. Properties of Starch Blends with Biodegradable Polymers

    Microsoft Academic Search

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

    2003-01-01

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

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

    E-print Network

    North Texas, University of

    and relatively low cost [1]. For applications where friction, wear, and adhesion properties are important adhesion for low density polyethylene (LDPE) and poly(ethylene terephthalate) (PET) [8]. Moreover, since for modifying the tribological properties of materials, because it only affects outer sur- face layers

  17. Homogenization in mechanical mixing involving polyvinyl chloride. II. Effect of different types of polymers on breakdown of PVC particulate structure and mixing mechanism

    Microsoft Academic Search

    S. Y. Kwak; N. Nakajima

    1995-01-01

    The process of mixing PVC with other polymers, including an examination of how these polymers contribute to the breakdown of the particulate structure of PVC, is described. The polymers were an immiscible nitrile rubber containing 22% acrylonitrile (NBR-22) and two miscible polymers, poly-?-caprolactone (PCL) and copolyester thermoplastic elastomer (trademark Hytrel). The mixing of PVC and NBR-30, as investigated in the

  18. Radiation effects on carbon fiber reinforced thermoplastics

    SciTech Connect

    Sasuga, Tsuneo; Udagawa, Akira; Seguchi, Tadao [Japan Atomic Energy Research Institute, Gunma (Japan)

    1993-12-31

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

  19. Impregnation technology for thermoplastic matrix composites

    NASA Astrophysics Data System (ADS)

    Gibson, A. G.; Manson, J.-A.

    1992-12-01

    This paper reviews the technology available for the impregnation of carbon and glass fibers with thermoplastic resins. Process models and the key material factors influencing the achievement of impregnation are outlined, then the processes by which impregnation is currently carried out are discussed. These techniques can be divided into three categories: direct melt, processes where there is intimate mingling of the solid constituents prior to melting of the resin, and operations where low resin viscosities are employed (solvent impregnation and processes involving reactive chain extension).

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

    SciTech Connect

    Gruber, N.D.; Lesko, J.J.; Harris, L.A. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)] [and others

    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.

  1. 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

  2. Surface grafting of carboxylic groups onto thermoplastic polyurethanes to reduce cell adhesion

    NASA Astrophysics Data System (ADS)

    Alves, P.; Ferreira, P.; Kaiser, Jean-Pierre; Salk, Natalie; Bruinink, Arie; de Sousa, Hermínio C.; Gil, M. H.

    2013-10-01

    The interaction of polymers with other materials is an important issue, being their surface properties clearly crucial. For some important polymer applications, their surfaces have to be modified. Surface modification aims to tailor the surface characteristics of a material for a specific application without affecting its bulk properties. Materials can be surface modified by using biological, chemical or physical methods. The aim of this work was to improve the reactivity of the thermoplastic polyurethane (TPU) material (Elastollan®) surface and to make its surface cell repellent by grafting carboxylic groups onto its surface. Two TPU materials were studied: a polyether-based TPU and a polyester-based TPU. The grafting efficiency was evaluated by contact angle measurements and by analytical determination of the COOH groups. Scanning electron microscopy (SEM) of the membranes surface was performed as well as cell adhesion tests. It was proved that the surfaces of the TPUs membranes were successfully modified and that cell adhesion was remarkably reduced.

  3. 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.

  4. 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.

  5. 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.

  6. Coupling of waste water treatment with storage polymer production

    Microsoft Academic Search

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

    1997-01-01

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

  7. Processing and characterization of long fiber thermoplastics

    NASA Astrophysics Data System (ADS)

    Thattai Parthasarathy, Krishnan Balaji

    Thermoplastic composites have found increasing use in transportation, military, and aerospace applications. Specifically, long fiber thermoplastics (LFT) have become well established as medium performance, high volume, and low cost materials due to high level of productivity in processing. The mechanical properties of LFT components are defined by the fiber/matrix system and also, to a large extent, by the process-induced flow orientation and fiber lengths. The orientations and fiber length are influenced significantly by the flow characteristics, processing method, and parameters. This work focuses on the rheological characterization of LFT processed via the extrusion-compression molding technique. The squeeze flow technique has been adopted to characterize the flow behavior under isothermal conditions. A transversely isotropic power-law model has been incorporated to capture the combined effect of shear and extensional flow behavior. The effects of temperature, fiber length, and fiber weight fraction of the flow characteristics were analyzed. This work was followed by process simulation of the extrusion-compression molding technique on a mass transit component. Process simulation was conducted to evaluate the flow of fiber-filled viscous charge during the molding process. Studies on optimum charge size and placement in the tool, press force, shrinkage, and warpage were also conducted. The predictions of molten charge, fiber orientation, and final mechanical properties were experimentally verified using various techniques. Finally, an alternate approach to design and produce ribbed LFT components is presented. LFT components with ribs can pose processing complexity since the flow of the material is restricted due to the high viscosity of the charge, particularly in narrow channels (rib location). An innovative method of incorporating ribbed features in molded parts is to use pre-consolidated continuous fiber reinforced thermoplastic (CFRT) sections that are co-molded with a skin of LFT. This work focuses on processing and performance evaluation in terms of the static and dynamic properties of LFTs co-molded with pre-consolidated CFRTs, LFTs with ribs, and LFTs without ribs of equal flexural rigidity. Results showed that the LFTs co-molded with CFRTs have higher static and dynamic properties with a progressive failure, as opposed to a brittle failure with lower static and dynamic properties exhibited by both the LFT with and without ribs.

  8. A thermo-mechanically-coupled large-deformation theory for amorphous polymers in a temperature range which spans their glass transition

    E-print Network

    Srivastava, Vikas

    Amorphous thermoplastic polymers are important engineering materials; however, their non-linear, strongly temperature- and rate-dependent elastic-viscoplastic behavior is still not very well understood, and is modeled by ...

  9. 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.

  10. Novel thermoplastic starch clay nanocomposite foams

    NASA Astrophysics Data System (ADS)

    Chen, Meng; Chen, Biqiong; Evans, Julian R. G.

    2005-10-01

    Novel thermoplastic starch (TPS)-clay nanocomposite foams were prepared by melt-processing. The use of urea as plasticizer avoids the cracking of TPS during storage and enhances the dispersion of ammonium-treated clay in TPS. X-ray diffraction shows an increase in the basal plane spacings of both natural and treated clays, suggesting formation of nanocomposites. Scanning electron microscopy shows spontaneously formed regular foam structures with 84% porosity in TPS-ammonium-treated clay. This does not form in TPS or TPS-natural clay nanocomposites. This result implies that the regular foam formation is due to the ammonium surfactant of clay, which produces ammonia gas acting as an internal blowing agent. Thermogravimetric analysis confirms this deduction.

  11. 40 CFR Table 6 to Subpart Jjj of... - Known Organic HAP Emitted From the Production of Thermoplastic Products

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Known Organic HAP Emitted From the Production of Thermoplastic Products 6 Table...Known Organic HAP Emitted From the Production of Thermoplastic Products Thermoplastic... Ethylene Glycol (107-21-1) Methanol (67-56-1) Methyl...

  12. 40 CFR Table 6 to Subpart Jjj of... - Known Organic HAP Emitted From the Production of Thermoplastic Products

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Known Organic HAP Emitted From the Production of Thermoplastic Products 6 Table...Known Organic HAP Emitted From the Production of Thermoplastic Products Thermoplastic... Ethylene Glycol (107-21-1) Methanol (67-56-1) Methyl...

  13. Effects of laminate sequencing on thermoforming of thermoplastic matrix composites

    Microsoft Academic Search

    M. Sadighi; E. Rabizadeh; F. Kermansaravi

    2008-01-01

    Continuous fiber-reinforced thermoplastic composites are promising materials for light-weight structural components. Their medium to high processing and temperature-dependent properties, and the complex deformation mechanisms that occur within the composite sheet during the forming, are main problems in the practical production of parts. Thermoforming is an effective fabrication method due to the reversible solid–liquid phase transformation of thermoplastic materials. Deep drawing

  14. Atomically smooth surfaces through thermoplastic forming of metallic glass

    NASA Astrophysics Data System (ADS)

    Kumar, Golden; Staffier, Peter A.; Blawzdziewicz, Jerzy; Schwarz, Udo D.; Schroers, Jan

    2010-09-01

    We demonstrate that atomically smooth surfaces can be generated by thermoplastic forming of metallic glasses. This is enabled by the flow associated with the contact-line motion which removes rough surface layer from the advancing metallic glass-air interface. The thermoplastically formed surface is two orders of magnitude smoother than a polished surface of the same alloy. This process is capable of generating atomically smooth surfaces and replicating nanoscale features in a single processing step, providing a versatile toolbox for nanofabrication.

  15. CREEP MODELING FOR INJECTION-MOLDED LONG-FIBER THERMOPLASTICS

    Microsoft Academic Search

    Ba Nghiep Nguyen; Vlastimil Kunc; Satish K. Bapanapalli

    2008-01-01

    This paper proposes a model to predict the creep response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the nonlinear viscoelastic behavior described by the Schaperys model. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber length and orientation distributions were

  16. Characterization of polyetheretherketone and other engineering thermoplastics

    SciTech Connect

    Whitaker, R.B.; Nease, A.B.; Yelton, R.O.

    1984-04-13

    Three engineering thermoplastic materials were characterized by thermal/spectroscopic means to assess their suitability in fiberglass-filled molding resins for Mound applications. The three resins examined were: polyetheretherketone (PEEK) from ICI, Ltd., polyetherimide (PEI) from General Electric, and polyethersulfone (PES) from ICI. Thermogravimetric analysis of the three thermoplastics in N/sub 2/ showed that all had a decomposition onset temperature greater than or equal to 525/sup 0/C with PEEK > PEI > PES. Melt thermal stability analyses of glass-filled PEEK and of PEI showed <1% weight loss after 2 hr (N/sub 2/). Thermomechanical analysis (TMA) of glass-filled PEEK revealed a low temperature (approx. 60/sup -/70/sup 0/C) transition below T/sub g/ (approx. 150/sup 0/C). This transition disappeared on subsequent TMA runs and did not reappear on aging at room temperature, which suggests it was the result of molding stresses. Extra transitions below T/sub g/ were also noted for PES and PEI. Direct probe/mass spectroscopy reconstructed ion chromatograms showed water and phenyl sulfone ions to be present in both PES and PEEK (and volatilized below 200/sup 0/C in vacuum). Water only was observed in PEI. The presence of phenyl sulfone in PEEK was confirmed by FT-IR, and sulfur was found in amounts up to 0.23% by weight in 30% glass-filled molding compounds. A polymerization solvent, such as diphenyl sulfone, is a probable source. Fluoride (from a monomer used in the PEEK polymerization) was also detected in amounts up to 0.17% by weight in the 30% fiberglass molding compounds.

  17. Combination of magnetic and enhanced mechanical properties for copolymer-grafted magnetite composite thermoplastic elastomers.

    PubMed

    Jiang, Feng; Zhang, Yaqiong; Wang, Zhongkai; Wang, Wentao; Xu, Zhaohua; Wang, Zhigang

    2015-05-20

    Composite thermoplastic elastomers (CTPEs) of magnetic copolymer-grafted nanoparticles (magnetite, Fe3O4) were synthesized and characterized to generate magnetic CTPEs, which combined the magnetic property of Fe3O4 nanoparticles and the thermoplastic elasticity of the grafted amorphous polymer matrix. Fe3O4 nanoparticles served as stiff, multiple physical cross-linking points homogeneously dispersed in the grafted poly(n-butyl acrylate-co-methyl methacrylate) rubbery matrix synthesized via the activators regenerated by electron transfer for atom transfer radical polymerization method (ARGET ATRP). The preparation technique for magnetic CTPEs opened a new route toward developing a wide spectrum of magnetic elastomeric materials with strongly enhanced macroscopic properties. Differential scanning calorimetry (DSC) was used to measure the glass transition temperatures, and thermogravimetric analysis (TGA) was used to examine thermal stabilities of these CTPEs. The magnetic property could be conveniently tuned by adjusting the content of Fe3O4 nanoparticles in CTPEs. Compared to their linear copolymers, these magnetic CTPEs showed significant increases in tensile strength and elastic recovery. In situ small-angle X-ray scattering measurement was conducted to reveal the microstructural evolution of CTPEs during tensile deformation. PMID:25954980

  18. Development of fuel cell bipolar plates from graphite filled wet-lay thermoplastic composite materials

    NASA Astrophysics Data System (ADS)

    Huang, Jianhua; Baird, Donald G.; McGrath, James E.

    A method with the potential to produce economical bipolar plates with high electrical conductivity and mechanical properties is described. Thermoplastic composite materials consisting of graphite particles, thermoplastic fibers and glass or carbon fibers are generated by means of a wet-lay (paper-making) process to yield highly formable sheets. The sheets are then stacked and compression molded to form bipolar plates with gas flow channels. Poly(phenylene sulfide) (PPS) based wet-lay composite plates have in-plane conductivity of 200-300 S cm -1, tensile strength of 57 MPa, flexural strength of 96 MPa and impact strength (unnotched) of 81 J m -1 (1.5 ft-lb in. -1). These values well exceed industrial as well as Department of Energy requirements or targets and have never been reached before for composite bipolar plates. The use of wet-lay sheets also makes it possible to choose different components including polymer, graphite particle and reinforcement for the core and outer layers of the plate, respectively, to optimize the properties and/or reduce the cost of the plate. The through-plane conductivity (around 20 S cm -1) and half-cell resistance of the bipolar plate indicate that the through-plane conductivity of the material needs some improvement.

  19. Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

    PubMed Central

    Hotta, Atsushi; Cochran, Eric; Ruokolainen, Janne; Khanna, Vikram; Fredrickson, Glenn H.; Kramer, Edward J.; Shin, Yong-Woo; Shimizu, Fumihiko; Cherian, Anna E.; Hustad, Phillip D.; Rose, Jeffrey M.; Coates, Geoffrey W.

    2006-01-01

    We report the design, synthesis, morphology, phase behavior, and mechanical properties of semicrystalline, polyolefin-based block copolymers. By using living, stereoselective insertion polymerization catalysts, syndiotactic polypropylene-block-poly(ethylene-co-propylene)-block-syndiotactic polypropylene and isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene triblock copolymers were synthesized. The volume fraction and composition of the blocks, as well as the overall size of the macromolecules, were controlled by sequential synthesis of each block of the polymers. These triblock copolymers, with semicrystalline end-blocks and mid-segments with low glass-transition temperatures, show significant potential as thermoplastic elastomers. They have low Young's moduli, large strains at break, and better than 90% elastic recovery at strains of 100% or less. An isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene pentablock copolymer was synthesized that also shows exceptional elastomeric properties. Notably, microphase separation is not necessary in the semicrystalline isotactic polypropylenes to achieve good mechanical performance, unlike commercial styrenic thermoplastic elastomers. PMID:17032769

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

    DOEpatents

    Soroushian, Parviz (Lansing, MI)

    2002-01-01

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

  1. Improvement of bonding properties of laser transmission welded, dissimilar thermoplastics by plasma surface treatment

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Sooriyapiragasam, S.; Behm, H.; Dahlmann, R.

    2015-05-01

    Compared to different welding methods such as ultrasonic welding, laser transmission welding is a relatively new technology to join thermoplastic parts. The most significant advantages over other methods are the contactless energy input which can be controlled very precisely and the low mechanical loads on the welded parts. Therefore, laser transmission welding is used in various areas of application, for example in medical technology or for assembling headlights in the automotive sector. However, there are several challenges in welding dissimilar thermoplastics. This may be due to different melting points on the one hand and different polarities on the other hand. So far these problems are faced with the intermediate layer technique. In this process a layer bonding together the two components is placed between the components. This means that an additional step in the production is needed to apply the extra layer. To avoid this additional step, different ways of joining dissimilar thermoplastics are investigated. In this regard, the improvement in the weldability of the dissimilar thermoplastics polyamide 6 (PA 6) and polypropylene (PP) by means of plasma surface modification and contour welding is examined. To evaluate the influence of the plasma surface modification process on the subsequent welding process of the two dissimilar materials, the treatment time as well as the storage time between treatment and welding are varied. The treatment time in pulsed micro wave excited oxygen plasmas with an electron density of about 1x1017 m-3 is varied from 0.5 s to 120 s and the time between treatment and welding is varied from a few minutes up to a week. As reference, parts being made of the same polymer (PP and PA 6) are welded and tested. For the evaluation of the results of the welding experiments, short-time tensile tests are used to determine the bond strength. Without plasma treatment the described combination of PA 6/PP cannot be welded with sufficient bond strength to withstand handling of the samples. In contrast, the tear-out force of previously plasma treated samples can be determined to up to 1400 N. The achieved bond strengths are higher than of untreated PP/PP welded parts (about 1000 N).

  2. A new technology for sandwich plates and structures based on the use of in-situ foamable thermoplastic films

    NASA Astrophysics Data System (ADS)

    Beukers, Adriaan

    The cost effectiveness of structures in transports is basically depending on the operational capability and availability, the so called structure effectiveness, per unit cost. These costs are mainly determined by the cost to manufacture (acquisition costs) and the costs to operate (mass) and to maintain (damage sensitivity). In this paper the attention is focused on a new approach leading to efficiency improving sandwich material concepts, structures and related manufacturing processes, satisfying the value for money criterion as formulated by the cost effectiveness criterion. The sandwich materials and technology applied are based on the use of thermoformable continuous fiber reinforced thermoplastic polymers, in particular E-glass reinforced polyetherimide (PEI).

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

    NASA Astrophysics Data System (ADS)

    Yoon, Pil Joong

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

  4. Hot embossing: a flexible and successful replication technology for polymer MEMS

    Microsoft Academic Search

    Mathias Heckele

    2003-01-01

    Molding of micro components from thermoplastic polymers has become a routinely used industrial production process. Besides the famous injection molding technology hot embossing is nearly unknown to most people in micro technology. Initially developed for first feasibility tests with microstructured moldinserts hot embossing has been developed during the last ten years to a flexible and successful replication technology for polymer

  5. Large-scale production, properties and commercial applications of polylactic acid polymers

    Microsoft Academic Search

    James Lunt

    1998-01-01

    Polylactic acids (PLA) are not new polymers. However, recent developments in the capability to manufacture the monomer economically from renewable feedstocks have placed these materials at the forefront of the emerging biodegradable plastics industry. Increasing realisation of the intrinsic properties of these polymers, coupled with a knowledge of how such properties can be manipulated to achieve compatibility with thermoplastics processing,

  6. Radioactive Waste from Nuclear Power Plants Part II. Thermal Properties of Waste\\/Polymer Products

    Microsoft Academic Search

    N. K. Ghattas; N. E. Ikladious; H. A. Shatta

    1989-01-01

    Simulating solutions of medium active borate waste from nuclear power plants are dried and immobilized in epoxy resin, phenol formaldehyde, polyester and poly methyl methacrylate. Thermogravimetric and differential thermogravimetric measurements are given for pure unloaded thermoset and thermoplastic polymer samples and compared with the thermograms of the same polymers loaded with 50 wt-% of dried waste powder. The aim of

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

    DOEpatents

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

    2008-04-29

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

  8. Improving the cellular morphology in high performance thermoplastics foams through blending

    NASA Astrophysics Data System (ADS)

    Cafiero, Livia; Sorrentino, Luigi; Iannace, Salvatore

    2014-05-01

    High performance thermoplastic blends based on Poly(ethylene naphthalate)/Poly(ether sulfone) polymers were prepared by melt compounding to study the correlations between composition, morphologies and cellular structure after foaming. Blends were employed to develop high performance foams with controlled cellular morphology by using CO2 as foaming agent. The role of composition, morphology and processing conditions on the dynamic-mechanical properties of solid blends and on the micro- and nano-cellular structures of their foams was analized. Dispersed PES both extended the service temperature and acted as gas reservoir in PEN based blends, lowering the foam density with respect to neat PEN. The dispersion of PEN drops in PES extended towards lower temperatures the PES foamability, allowing the nucleation and growth of bubbles and reducing the foam density.

  9. Microstructural Characterization of Polymers with Positrons

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.

    1997-01-01

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

  10. Accelerated Strength Testing of Thermoplastic Composites

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  11. Analytical Prediction of Forming Limits for Thermoplastic Tubes

    NASA Astrophysics Data System (ADS)

    Azhikannickal, Elizabeth; Jain, Mukesh K.

    2005-08-01

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

  12. Rheological properties of amorphous and semicrystalline polylactic acid polymers

    Microsoft Academic Search

    Qi Fang; Milford A Hanna

    1999-01-01

    Corn starch fermentation provides an abundant supply of lactic acid. Polymerization of lactic acid into polylactic acid (PLA) produces a biodegradable thermoplastic polyester with excellent functional properties comparable to many petroleum-based plastics. PLA polymers are made into useful items using thermal processes, such as injection molding and extrusion. Therefore, its rheological properties, especially the shear viscosity (?), have important effects

  13. Preparation, characterization and formation mechanism of thermoplastic polyurethane nanostructures using solution wetting template.

    PubMed

    Han, Guiquan; Liu, Yuhong; Luo, Jianbin; Lu, Xinchun; Dong, Ying

    2011-11-01

    Template wetting with polymer solutions has not been well understood up to now, and the formation mechanism of polymer nanostructures with this method is still to be revealed. In the present work, thermoplastic polyurethane (TPU) nanostructures were prepared by wetting cylindrical nanopores in an anodic aluminum oxide (AAO) membrane with TPU solution in dimethylformamide (DMF) followed by solvent evaporation. Both tubular structures and solid structures were simultaneously observed at four different concentrations of TPU solutions (i.e., 5, 7, 10, and 15 wt%) by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Furthermore, a transition from a tubular structure to a solid structure was also found at a higher concentration of TPU solution (15 wt%). It is speculated that the top part of the single nanostructure is tubular, and the lower part is solid. A "capillary wetting-evaporation-deposition" mechanism is given to explain such a phenomenon. According to this mechanism, the higher polymer concentration, the larger amount of solution, and the smaller pore size are believed to be beneficial for the formation of solid structures. PMID:22413371

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  15. Polymer composite thermistors for temperature and current sensors

    NASA Astrophysics Data System (ADS)

    Strümpler, Ralf

    1996-12-01

    The electrical resistivity of polymer composites is studied as a function of temperature. The initial resistivity ? of thermoplastic or thermoset containing a metallic filler is in the range of 1-10×10-2 ? cm. Around the curing temperature of epoxies, the resistivity increases by eight to twelve orders of magnitude. For thermoplastic polymers, however, the transition temperature is related to the melting temperature at which a strong volume increase occurs. Hence, the choice of polymer and its processing determine the transition temperature from a conducting state to an insulating state. For a variety of polymers we have observed transitions between 80 and 200 °C. Due to a sharp and strong transition at a predetermined temperature, such materials can be used as temperature sensors. Since the resistivity of the cold state is low, they can also carry rather high currents. The balance between heating and cooling determines then a critical value for the current. Thus, the materials can also serve as current sensors.

  16. Flexural fatigue of short fiber reinforced high temperature thermoplastics

    SciTech Connect

    Yau, S.; Chou, T.W.

    1985-04-01

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

  17. Thermoplastic veils as advanced modifiers for multifunctional fiber reinforced composites

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  19. Thermoplastic Explosive Compositions on the Base of Hexanitrohexaazaisowurtzitane

    NASA Astrophysics Data System (ADS)

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

    2006-08-01

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

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

    NASA Technical Reports Server (NTRS)

    Santare, Michael H.; Pipes, R. Byron

    1992-01-01

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

  1. Cure kinetics, morphologies, and mechanical properties of thermoplastic/MWCNT modified multifunctional glassy epoxies prepared via continuous reaction methods

    NASA Astrophysics Data System (ADS)

    Cheng, Xiaole

    The primary goal of this dissertation is to develop a novel continuous reactor method to prepare partially cured epoxy prepolymers for aerospace prepreg applications with the aim of replacing traditional batch reactors. Compared to batch reactors, the continuous reactor is capable of solubilizing and dispersing a broad range of additives including thermoplastic tougheners, stabilizers, nanoparticles and curatives and advancing epoxy molecular weights and viscosities while reducing energy consumption. In order to prove this concept, polyethersulfone (PES) modified 4, 4'-diaminodiphenylsulfone (44DDS)/tetraglycidyl-4, 4'-diaminodiphenylmethane (TGDDM) epoxy prepolymers were firstly prepared using both continuous reactor and batch reactor methods. Kinetic studies confirmed the chain extension reaction in the continuous reactor is similar to the batch reactor, and the molecular weights and viscosities of prepolymers were readily controlled through reaction kinetics. Atomic force microscopy (AFM) confirmed similar cured network morphologies for formulations prepared from batch and continuous reactors. Additionally tensile strength, tensile modulus and fracture toughness analyses concluded mechanical properties of cured epoxy matrices produced from both reactors were equivalent. Effects of multifunctional epoxy compositions on thermoplastics phase-separated morphologies were systematically studied using a combination of AFM with nanomechanical mapping, spectroscopic and calorimetric techniques to provide new insights to tailor cured reaction induced phase separation (CRIPS) in multifunctional epoxy blend networks. Furthermore, how resultant crosslinked glassy polymer network and phase-separated morphologies correlated with mechanical properties are discussed in detail. Multiwall carbon nanotube (MWCNT)/TGDDM epoxy prepolymers were further prepared by combining the successful strategies for advancing epoxy chemistries and dispersing nanotubes using the continuous reactor. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to characterize the MWCNT dispersion states and stabilization in epoxy prepolymer matrix after continuous process and during curing cycles. Additionally, electrical conductivities and mechanical properties of final cured MWCNT/TGDDM composites were measured and discussed in view of their corresponding MWCNT dispersion states. Ternary blends of MWCNT reinforced thermoplastic/epoxy prepolymers were prepared by the continuous reactor. Influence of MWCNT on the CRIPS mechanism and the cured morphologies were systematically investigated using SEM and rheological analysis. Incorporation of MWCNT in thermoplastic/epoxy matrices can lead to a morphological transformation from phase inverted, to co-continuous, and to droplet dispersed morphology. In additional, dynamic mechanical analysis revealed the heterogeneity of MWCNT dispersion in thermoplastic/thermosets systems.

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

    Microsoft Academic Search

    T. Czvikovszky; H. Hargitai

    1997-01-01

    Thermoplastic polymers can be fiber-reinforced in the recycling step through a reactive modification of the interface between the polymer matrix and fiber. Recollected automobile bumpers made of polypropylene copolymers have been reinforced during the reprocessing with eight different types of high-strength fibers, with waste cord-yarns of the tire industry. A thin layer reactive interface of acrylic oligomers has been applied

  3. Microinjection moulding of polymer microfluidic devices

    Microsoft Academic Search

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

    2009-01-01

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

  4. Gas diffusion barrier layers for transparent polymer packages for optical MEMS

    Microsoft Academic Search

    M. Schmidt; S. Zinober; R. Müller-Fiedler; C. Müller; H. Reinecke

    2009-01-01

    In this paper we present our results on polymer permeability control by organo-SiOx-layers (Aquacer©, Lipocer©1). The goal of our investigations is to use transparent polymers for optical MEMS-packaging. In contrast to costly MEMS-packages made of glass, thermoplastic polymers provide high transparency, low costs and good processability. Their main drawbacks regarding their usage for MEMS-packaging are their high thermal expansion coefficient

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

    PubMed Central

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

    2014-01-01

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

  6. Hybrid yarn for thermoplastic fibre composites Publications Department

    E-print Network

    Hybrid yarn for thermoplastic fibre composites Publications Department publications Hybrid yarn. Contents Introduction Wind Turbine Blade Inspection Cover for a Wind Turbine Blade Car Door-Post Air Texturing of the Hybrid Yarn Materials and Mechanical Properties Press Consolidation of Hybrid Yarn Fabrics

  7. THE NUCLEATION OF MICROCELLULAR FOAMS IN SEMI CRYSTALLINE THERMOPLASTICS

    Microsoft Academic Search

    J. S. Colton

    1989-01-01

    The nucleation of microcellular foams in amorphous thermoplastics has been performed by supersaturation with gas at an elevated temperature. Pressure and temperature are then carefully reduced in the vicinity of the glass transition temperature of the material. The result is a foam structure with cells on the order of 10 microns. This material exhibits greatly increased impact strength, as well

  8. Configurational mechanics of necking phenomena in engineering thermoplastics

    Microsoft Academic Search

    A. Chudnovsky; S. Preston

    2002-01-01

    Necking is a significant part of the yielding process in many thermoplastics. It starts as strain localization associated with microshear banding and\\/or cavitations and appears as a domain of oriented (drawn) material, i.e., a “neck”, separated from the domain of original (isotropic) material by a narrow transition zone, which appears as a distinct boundary of the neck region. On further

  9. Simulation of shrinkage and warpage of semi-crystalline thermoplastics

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Borchmann, N.; Spekowius, M.; Weber, M.; Schöngart, M.

    2015-05-01

    Today, the simulation of the injection molding process is state of the art. Besides the simulation of the manufacturing process, commercial simulation tools allow a prediction of the structural properties of the final part. Especially the complex shrinkage and warpage behavior is of interest as it significantly influences the part quality. Although modern simulation tools provide qualitatively correct results for several materials and processing conditions, significant deviations from the real component's behavior can occur for semi-crystalline thermoplastics. One underlying reason is the description on the macro scale used in these simulation tools. However, in semi-crystalline materials significant effects take place on the micro scale, e.g. crystalline superstructures that cannot be neglected. As part of a research project at IKV, investigations are carried out to improve the simulation accuracy of shrinkage and warpage. To point out differences in the accuracy of commercially available simulation tools, a reference part is computed for the materials polypropylene and polyoxymethylene. The results are validated by injection molding experiments. The shrinkage and warpage behavior is characterized by optical measuring technology. In future, models for the description of the pvT behavior of semi-crystalline thermoplastics will be implemented into the software package SphäroSim which was developed at IKV. With this software, crystallization kinetics for semi-crystalline thermoplastics can be calculated on the micro scale. With the newly implemented pvT models the calculation of shrinkage and warpage for semi-crystalline thermoplastics will be enabled on the micro scale.

  10. Atomically smooth surfaces through thermoplastic forming of metallic glass

    E-print Network

    Gelfond, Michael

    metallic glasses BMGs can be prepared from a wide range of chemical compositions and they display highAtomically smooth surfaces through thermoplastic forming of metallic glass Golden Kumar,a Peter A of metallic glasses. This is enabled by the flow associated with the contact-line motion which removes rough

  11. Development and evaluation of thermoplastic street maintenance material

    NASA Technical Reports Server (NTRS)

    Siemens, W. D.

    1973-01-01

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

  12. Controlled Alloying of CSM Roofing Membranes with Thermoplastic Resins

    Microsoft Academic Search

    Jimmie L. Stanton

    1996-01-01

    Single-ply roofing membranes based on CSM have been effective in commercial installation for over twenty years. Selective blending of thermoplastic resins, CPE (CM) and EVA, into a standard CSM formulation have been performed to evaluate the effect on calendering, accelerated aging and seaming ability. The effect of these resins on other physical properties are also characterized. Further, care must also

  13. TPE's with low permeability, high damping. [ThermoPlastic Elastomers

    Microsoft Academic Search

    M. J. Thompson; M. A. Lebel; K. J. Robinson

    1991-01-01

    This article examines the characteristics of the thermoplastic elastomer Sarlink 2000. Topics discussed include morphology, rheology, thermo-mechanical properties, thermal properties, and physical properties. These properties are compared to the properties of thermoset butyl rubber compounds which Sarlink 2000 is targeted to replace in many applications.

  14. Nonlinear Flexural Deflection of Thermoplastic Foam Core Sandwich Beam

    Microsoft Academic Search

    Kwang Joon Yoon; C. K. Kim; Hoon C. Park

    2002-01-01

    Nonlinear flexural deflection behavior of foam core sandwich beams hasbeen experimentally investigated. The experimental data were compared with the predicted results obtained from a proposed analytical method and the finite element analysis. Sandwich beams with thermoplastic foam core and carbon\\/epoxy fabric faces were manufactured using the vacuum bagging process. To investigate the effect of the face thickness on the nonlinear

  15. Interlaminar fracture of carbon-thermoplastic polyimide composites

    Microsoft Academic Search

    Jiang Zhou; Tianbai He; Jin Zhang; Mengxian Ding

    1994-01-01

    Mode I interlaminar fracture of a novel amorphous thermoplastic polyimide reinforced with unidirectional carbon fibre has been studied experimentally using double cantilever beam specimens and scanning electron microscopy. Three kinds of composite were manufactured from different monomeric reactant solutions which were prepared by using different alcohol solvents. The values of fracture toughness of these three composites were measured to construct

  16. Processing and characterization of unidirectional thermoplastic nanocomposites

    NASA Astrophysics Data System (ADS)

    Narasimhan, Kameshwaran

    The manufacture of continuous fibre-reinforced thermoplastic nanocomposites is discussed for the case of E-Glass reinforced polypropylene (PP) matrix and for E-Glass reinforced Polyamide-6 (Nylon-6), with and without dispersed nanoclay (montmorillonite) platelets. The E-Glass/PP nanocomposite was manufactured using pultrusion, whereas the E-Glass/Nylon-6 nanocomposite was manufactured using compression molding. Mechanical characterization of nanocomposites were performed and compared with traditional microcomposites. Compressive as well as shear strength of nanocomposites was improved by improving the yield strength of the surrounding matrix through the dispersion of nanoclay. Significant improvements were achieved in compressive strength and shear strength with relatively low nanoclay loadings. Initially, polypropylene with and without nanoclay were melt intercalated using a single-screw extruder and the pultruded nanocomposite was fabricated using extruded pre-impregnated (pre-preg) tapes. Compression tests were performed as mandated by ASTM guidelines. SEM and TEM characterization revealed presence of nanoclay in an intercalated and partially exfoliated morphology. Mechanical tests confirmed significant improvements in compressive strength (˜122% at 10% nanoclay loading) and shear strength (˜60% at 3% nanoclay loading) in modified pultruded E-Glass/PP nanocomposites in comparison with baseline properties. Uniaxial tensile tests showed a small increase in tensile strength (˜3.4%) with 3% nanoclay loading. Subsequently, E-Glass/Nylon-6 nanocomposite panels were manufactured by compression molding. Compression tests were performed according to IITRI guidelines, whereas short beam shear and uni-axial tensile tests were performed according to ASTM standards. Mechanical tests confirmed strength enhancement with nanoclay addition, with a significant improvement in compressive strength (50% at 4% nanoclay loading) and shear strength (˜36% at 4% nanoclay loading) when compared with the baseline E-Glass/Nylon-6. Uni-axial tensile tests resulted in a small increase in tensile strength (˜3.2%) with 4% nanoclay loading. Also, hygrothermal aging (50°C and 100% RH) of baseline and nanoclay modified (4%) E-Glass/Nylon-6 was studied. It was observed that the moisture diffusion process followed Fickian diffusion. E-Glass/Nylon-6 modified with 4% nanoclay loading showed improved barrier performance with a significant reduction (˜30%) in moisture uptake compared to baseline E-Glass/Nylon-6 composites. Significant improvement in mechanical properties was also observed in hygrothermally aged nanocomposite specimens when compared with the aged baseline composite.

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

  18. Modification of wood fiber with thermoplastics by reactive steam-explosion processing

    NASA Astrophysics Data System (ADS)

    Renneckar, Scott H.

    For the first time, a novel processing method of co-refining wood and polyolefin (PO) by steam-explosion was scientifically explored for wood-thermoplastic composites without a coupling agent. Traditional studies have addressed the improvement of adhesion between components of wood thermoplastic composites through the use of coupling agents such as maleated PO. The objective of this study was to increase adhesion between wood and PO through reactive processing conditions of steam-explosion. PO characteristics, such as type (polyethylene or polypropylene), form (pellet, fiber, or powder) and melt viscosity were studied along with oxygen gas content of the steam-explosion reactor vessel. Modification of co-processed wood fiber was characterized in four studies: microscopy analysis of dispersion of PO with wood fiber, sorption properties of co-processed material, chemical analysis of fractionated components, and morphological investigation of co-processed material. Two additional studies are listed in the appendices that relate to adsorption of amphiphilic polymers to the cellulose fiber surface, which is one hypothesis of fiber surface modification by co-steam-explosion. Microscopy studies revealed that PO melt viscosity was found to influence the degree of dispersion and uniformity of the steam-exploded material. The hygroscopic nature of the co-processed fiber declined as shown by sorption isotherm data. Furthermore, a water vapor kinetics study found that all co-refined material had increased initial diffusion coefficients compared to the control fiber. Chemical changes in fractionated components were PO-type dependent. Lignin extracted from co-processed wood and polyethylene showed PO enrichment determined from an increase of methylene stretching in the Fourier Transform infrared subtraction spectra, while lignin from co-processed wood and polypropylene did not. Additionally, extracted PO showed indirect signs of oxidation as reflected by fluorescence studies. Solid state nuclear magnetic resonance spectroscopy revealed a number of differences in the co-processed materials such as increased cellulose crystallinity, new covalent linkages and an alternative distribution of components on the nanoscale reflected in the T1rho relaxation parameter. Steam-explosion was shown to modify wood fiber through the addition of "non-reactive" polyolefins without the need for coupling agents. In light of these findings, co-refining by steam-explosion should be viewed as a new reactive processing method for wood thermoplastic composites.

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

    NASA Technical Reports Server (NTRS)

    Theil, Michael H.

    1988-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (inventor)

    1992-01-01

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

  1. Overview on energetic polymers

    SciTech Connect

    Boileau, J. [Direction de la Recherche et de la Technologie, Paris (France)

    1996-07-01

    Energetic materials for missiles, gun munitions or pyrotechnic devices often are mixtures in a biphasic form, with a filler and a binder. To satisfy the user needs, an analysis of functional requirements together with constraints (safety, vulnerability, aging, environment, disposal, price) is useful to choose a convenient binder. From this point of view numerous synthetic energetic polymers proposed or developed as binders are reviewed with regard to their syntheses, processing, properties and possible uses. These polymers contain explosophore groups: C-NO{sub 2} aliphatic or aromatic, ONO{sub 2}, NNO{sub 2}, NF{sub 2} and N{sub 3}. Some research projects are suggested. Among them in the list of published polymers, following a NIMIC (NATO) suggestion, note the reason of a development interruption. Some dinitropolystyrene-polyvinyl nitrate mixtures or copolymers could exhibit interesting properties. For unknown reasons, some mixtures of crystalline filler with polymer binder, generally in a biphasic form, may also be monophasic for a same composition. What properties are modified between both forms (e.g. combustion mechanisms, erosion, ideal character of the detonation)? It is also interesting to pursue a newly open route to thermo-plastic elastomers. 50 refs., 1 tab.

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

    PubMed

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

    2013-11-26

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

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

    NASA Technical Reports Server (NTRS)

    Howes, Jeremy C.; Loos, Alfred C.

    1987-01-01

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

  4. Characterization of poly(methyl methacrylate) and thermoplastic polyurethane-carbon nanofiber composites produced by chaotic mixing

    NASA Astrophysics Data System (ADS)

    Jiminez, Guillermo A.

    Chaotic mixing is a novel mixing technique offering high mixing efficiency even under mild shearing conditions. In this work, chaotic mixing was used to prepare composites of carbon nanofibers and two thermoplastic polymers---poly (methyl methacrylate) (PMMA) and thermoplastic polyurethanes (TPU)---and their electrical, mechanical, and thermal properties were evaluated. The TPU systems were based on the reaction products of 4,4'-diphenylmethane diisocyanate, (MDI), soft segment polyol, and 1,4-butanediol as chain extender. Soft segment polyols in the form of poly(propylene glycol) (PPG), and poly(epsilon-caprolactone)diol (PCL) were used to obtain respectively amorphous and crystalline soft segments. Of these, the TPU system based on crystalline soft segment exhibited shape memory effects. Both, as-received untreated carbon nanofibers (CNF) with a very low amount of atomic oxygen on the surface, and oxidized carbon nanofibers (CNFOX) were used. CNFOX was also modified by esterifying with PPG to produce a third type of carbon nanofiber named CNFOL. These carbon nanofibers were examined by X-ray photoelectron spectroscopy to determine the elemental composition of the surface, and by scanning electron microscopy and transmission electron microscopy to determine the surface morphology.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Astrom, B. T.

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

  8. Microwave facilities for welding thermoplastic composites and preliminary results.

    PubMed

    Ku, H S; Siores, E; Ball, J A

    1999-01-01

    The wide range of applications of microwave technology in manufacturing industries has been well documented (NRC, 1994; Thuery, 1992). In this paper, a new way of joining fibre reinforced thermoplastic composites with or without primers is presented. The microwave facility used is also discussed. The effect of power input and cycle time on the heat affected zone (HAZ) is detailed together with the underlying principles of test piece material interactions with the electromagnetic field. The process of autogenous joining of 33% by weight of random glass fibre reinforced Nylon 66, polystyrene (PS) and low density polyethylene (LDPE) as well as 23.3% by weight of carbon fibre reinforced PS thermoplastic composites is discussed together with developments using filler materials, or primers in the heterogenous joining mode. The weldability dependence on the dielectric loss tangent of these materials at elevated temperatures is also described. PMID:10687151

  9. Investigations of micromechanical and failure mechanisms of toughened thermoplastics by electron microscopy

    SciTech Connect

    Michler, G.H.; Starke, J.U. [Martin-Luther-Univ. Halle-Wittenburg, Merseburg (Germany)

    1996-12-31

    The competitive influence of particle diameter and interparticle distance on the toughening mechanism was studied in various thermoplastics. The morphology, deformation, and fracture properties were also investigated.

  10. Joining of aluminum and long fiber thermoplastic (LFT) composites

    NASA Astrophysics Data System (ADS)

    Kulkarni, Rahul R.

    Metal/polymer joints are used in variety of areas: aerospace, automotive, prosthetic devices, electronic packaging, etc. The present study involves a tailcone, which is currently made of aluminum and a new design will involve a joint between aluminum and long fiber thermoplastic (LFT) composite. The new tailcones were processed by insert molding, also called as extrusion-compression molding. Finite element (FE) models were used to obtain a temperature profile during cooling of tailcone from processing and to estimate thermal stresses generated. Experimental verification of the temperature profile was obtained by IR thermography. It was observed that the LFT part of the tailcone cooled faster than aluminum. During the cooling of the tailcone, the aluminum insert acted as a heat sink because of the large difference between the thermal conductivities of aluminum and the LFT composite. Thermal stresses computed were 2.5 MPa and 12 MPa in the case of beaded and threaded insert tailcones, respectively. Static pullout tests were done to obtain an insight into the failure mechanisms of the joint between aluminum and LFT composite. Both the tailcone configurations, with beaded and threaded inserts, showed about the same average peak load, 96 kN. Radiographic and metallographic studies showed that the damage at the interface between aluminum and LFT composite occurred in the form of microcracks, followed by complete separation normal to the stress axis. The tailcones housed in projectiles were test fired and it was found that the HBTs disintegrated immediately after they came out of the barrel. A new design was proposed to overcome the drawbacks of the HBTs, called filled-back tailcone (FBT). Static pullout tests on FBTs showed no failure of the tailcones, which was in accord with the test firing where tailcone did not fail. The study of aluminum/LFT composite interfaces was extended into the realm of laminated composites. Laminated composites were made in the form of alternate layers between LFT composite and metal (called as LMLs) such as aluminum by compression molding. Interlaminar shear strength of the laminates was determined by short beam three-point bend tests. It was found that the strength depends on the surface quality of the aluminum. ILSS in the case of mean roughness (Ra) 3.3 mum was 34.5 MPa, whereas 24 MPa in the case of mean roughness of 0.4 mum. Tensile test results showed that average Young's modulus and tensile strength of the laminate were 44.8 GPa and 244 MPa, respectively. Rule-of-mixtures predictions matched closely with the experimental results. Low velocity impact (LVI) tests showed that the specific perforation energy of the LMLs was significantly higher (7.1 J/kg m-2) than that of LFT composite (1.2 J/kg m-2). This new type of hybrid composite, LML, is quite promising for a variety of applications in automotive as well as aerospace industries.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  12. Stress-induced structural changes in thermoplastic composites

    Microsoft Academic Search

    Kitano

    1991-01-01

    Polymeric Composites: Cyclic stress effects on PEEK (Poly-ether-ether-ketone) matrix thermoplastic composite system were examined by thermal-analysis techniques: DSC (Differential Scanning Calorimeter), DMA (Dynamic Mechanical Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), DGT (Density Gradient Technique), and WAXS (Wide angle X-ray Scattering). These measurements identified for the first time stress-induced crystallization of PEEK below the

  13. Biodegradation of a Starch Containing Thermoplastic in Standardized Test Systems

    Microsoft Academic Search

    M. SCANDOLA; L. FINELLI; B. SARTI; J. MERGAERT; J. SWINGS; K. RUFFIEUX; E. WINTERMANTEL; J. BOELENS; B. DE WILDE; W.-R. MÜLLER; A. SCHÄFER; A.-B. FINK; H. G. BADER

    1998-01-01

    Biodegradation of the commercial starch-based thermoplastic Mater Bi (MB) ZI01U was investigated in six different test systems: (1) aqueous aerobic (AQ-AE), (2) aqueous anaerobic (AQ-ANA), (3) in vitro in the presence of the microorganism Acidovorax avenae avenae (MICRO), (4) controlled compost (COCO), (5) composting bins (COBI) and (6) high solids anaerobic digestion (HSAD). MB ZI01U was found to biodegrade in

  14. Studies on the Blends of Polyamide66 and Thermoplastic Polyimide

    Microsoft Academic Search

    Xi-Qiang Liu; Ke-Jun Zhan; Xiao-Jun Wu; Rui-Ying Bao; Wei Yang; Ming-Bo Yang

    2010-01-01

    The influence of the content of thermoplastic polyimide (TPI) on the structure and properties of polyamide66 (PA66)\\/TPI blends was studied. The results indicated that the addition of TPI showed little influence on the mechanical properties of the PA66\\/TPI blends, and the melting and crystallization behavior of the TPI\\/PA66 blends was not changed obviously. However, the addition of a small quantity

  15. Mechanical behavior of lightweight thermoplastic fiber–metal laminates

    Microsoft Academic Search

    G. Reyes; H. Kang

    2007-01-01

    Lightweight thermoplastic-based fiber–metal laminates were developed based on self-reinforced polypropylene and glass fiber-reinforced polypropylene composite materials and an aluminum alloy 2024-T3. The laminates were manufactured using a fast one-step cold press manufacturing procedure. The mechanical behavior of the laminates was then investigated under tensile and fatigue loading conditions. The tensile properties of the plain aluminum, the composite materials and the

  16. Urea and ethanolamine as a mixed plasticizer for thermoplastic starch

    Microsoft Academic Search

    X. F. Ma; J. G. Yu; J. J. Wan

    2006-01-01

    Mixtures of urea and ethanolamine were used as plasticizers for preparing thermoplastic starch (TPS) in a single-screw extruder. The interaction between urea\\/ethanolamine and starch was investigated using Fourier Transform Infrared (FT-IR). Glass transition temperature of TPS was tested by Differential scanning calorimetry (DSC). Both FT-IR and DSC proved that the mixture of urea and ethanolamine could form more stable and

  17. Recyclability of a layered silicate–thermoplastic olefin elastomer nanocomposite

    Microsoft Academic Search

    M. R. Thompson; K. K. Yeung

    2006-01-01

    A multiple-pass study was undertaken with a layered silicate–thermoplastic olefin elastomer (TPO) nanocomposite to study the impact of processing history on the properties of the material. A set of 10 passes were completed through a co-rotating intermeshing twin-screw extruder with samples collected to monitor changes in the composite. The microstructure of the nanocomposite was characterized using TEM, XRD, FT-IR, steady

  18. Numerical Modeling for Combustion of Thermoplastic Materials in Microgravity

    NASA Technical Reports Server (NTRS)

    Butler, Kathryn M.

    1997-01-01

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

  19. Rechargeable lithium battery employing a new ambient temperature hybrid polymer electrolyte based on PVK+PVdF–HFP (copolymer)

    Microsoft Academic Search

    M. S. Michael; S. R. S. Prabaharan

    2004-01-01

    We describe here for the first time, our recent success in developing an ambient temperature Li+ conducting solid polymer electrolyte (SPE) using the concept of polymer alloying upon blending two thermoplastic polymers such as poly(vinylidene) fluoride-hexafluoropropylene (PVdF–HFP-copolymer) and poly(N-vinylcarbazole), PVK and achieved the room temperature electrolytic conductivity (?i) of 0.7×10?3S\\/cm for a typical composition of PVdF–HFP copolymer\\/PVK blend mixed with

  20. Microstructural Characterization of Polymers by Positron Lifetime Spectroscopy

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.

    1996-01-01

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

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Thermoplastics Thermoplastic Chemical a Vessel capacity(cubic meters) Vapor pressure b (kilopascals) ASA/AMSAN c Styrene/ acrylonitrile mixture ? 3.78 ? 0.47 Acrylonitrile ? 75.7 ? 1.62 SAN, continuous d All...

  2. LaRC TPI 1500 series polymers

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Bai, Jia-Mo

    1990-01-01

    The crystallization behavior and the melt flow properties of two batches of 1500 series LaRC-TPI polymers from Mitsui Toatsu Chemicals (MTC) were investigated. The characterization methods include Differential Scanning Calorimetry, the x ray diffractography and the melt rheology. The as-received materials possess initial crystalline melting peak temperatures of 295 and 305 C, respectively. These materials are less readily recrystallizable at elevated temperatures when compared to other semicrystalline thermoplastics. For the samples annealed at temperatures below 330 C, a semicrystalline polymer can be obtained. On the other hand, a purely amorphous structure is realized in the samples annealed at temperatures above 330 C. Isothermal crystallization kinetics were studied by means of the simple Avrami equation. The viscoelastic properties at elevated temperatures below and above glass transition temperature of the polymers were measured. Information with regard to the molecule sizes and distributions in these polymers were also extracted from melt rheology.

  3. Effect of inter-laminar adhesive on yielding behavior of aluminum fiber-reinforced thermoplastic composite laminates

    SciTech Connect

    Sun, W. [Drexel Univ., Philadelphia, PA (United States). Dept. of Mechanical Engineering and Mechanics

    1994-12-31

    An adhesive stress-release model is proposed to predict the thermal residual stress released due to the presence of adhesive layer in hybrid aluminum fiber/polymer laminate. The model is developed based on the thermal curing temperature and composite constituent properties, and is used to determine the laminate initial yielding and deformation behavior. The adhesive layer functions as a compliant layer to release the thermal residual stresses and to delay the yield occurrence, thus enhances the laminates deformation behavior. Compared with available experimental data for graphite/PPS and glass/PPS with 2024-T3 or 7075-T6 aluminum hybrid thermoplastic laminates, the proposed model presents a better prediction than some other commonly used models.

  4. Polymer composites prepared from heat-treated starch and styrene-butadiene latex

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermoplastic starch/latex polymer composites were prepared using styrene–butadiene (SB) latex and heat-treated cornstarch. The composites were prepared in a compression mold at 130 °C, with starch content 20%. An amylose-free cornstarch, waxy maize, was used for this research and the heat treatment...

  5. Morphology of Thermoplastic Elastomers:Stereoblock Polypropylene

    SciTech Connect

    Pople, John A

    2002-08-06

    The morphologies of low-density (0.86 g/cm{sup 3}), elastomeric polypropylene (ePP) derived from bis(2-arylindenyl) hafnium dichloride were investigated using a combination of polarized optical microscopy (OM), differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS), Fourier transform infrared (FT-IR) spectroscopy, and tapping mode atomic force microscopy (TMAFM). These low-crystallinity polypropylenes, when crystallized isothermally from the melt, exhibit morphologies reminiscent of classical semi-crystalline polymers. The presence of lamellae, cross-hatching, hedrites, and spherulites was revealed by high resolution TM-AFM. These elastomeric polypropylenes can be fractionated into components of different average tacticities and crystallinities, but similar molecular mass. The analysis of the morphologies of all of the fractions revealed both large hierarchical structures and cross-hatching typical of the {alpha}-modification of crystalline isotactic polypropylene for all but the lowest crystalline ether soluble fraction. Evidence for high-melting crystals in all of the fractions are most consistent with a stereoblock microstructure of atactic and isotactic sequences.

  6. Polymer composites for temperature and current sensors

    NASA Astrophysics Data System (ADS)

    Struempler, Ralf G.

    1996-04-01

    The electrical resistivity of polymer composites is studied as a function of temperature. The initial resistivity (rho) of thermoplastic or thermoset containing a metallic filler is in the range of 1 - 10 (DOT) 10-2 (Omega) (DOT)cm. Around curing temperature of epoxies, the resistivity increases by eight to twelve orders of magnitude. For thermoplastic polymers, however, the transition temperature is related to the melting temperature at which a strong volume increase occurs. Hence, the choice of polymer and its processing determine the transition temperature from a conducting state to an insulating state. For a variety of polymers we have observed transitions between 80 degree(s)C and 200 degree(s)C. Due to a sharp and strong transition at a predetermined temperature, such materials can be used as temperature sensors. Since the resistivity of the cold state is low, they can also carry rather high currents. The balance between heating and cooling determines then a critical value for the current. Thus, the materials can also serve as a current sensors.

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

    PubMed Central

    Mengeloglu, Fatih; Karakus, Kadir

    2008-01-01

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

  8. Fabrication of robust and thermally stable superhydrophobic nanocomposite coatings based on thermoplastic polyurethane and silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Seyfi, Javad; Jafari, Seyed Hassan; Khonakdar, Hossein Ali; Sadeghi, Gity Mir Mohamad; Zohuri, Gholamhossein; Hejazi, Iman; Simon, Frank

    2015-08-01

    In this paper, superhydrophobic nanocomposite coatings based on thermoplastic polyurethane (TPU) and modified nanosilica were fabricated using a simple solution-based method. The main challenge was to impart superhydrophobicity to an intrinsically hydrophilic polymer substrate. The prepared nanocomposite coatings were characterized by means of scanning electron microscopy, confocal microscopy and X-ray photoelectron spectroscopy. Based on the obtained results, it was proved that in order to achieve superhydrophobicity, no TPU macromolecule should be present on the coating's top layer, thus a complete coverage of coating's top layer by nanosilica particles was necessary for achieving ultra water repellent coatings. Mechanical and thermal resistance of the coatings, which are the main challenges in commercializing superhydrophobic surfaces, were also studied by drop impact and thermal annealing tests, respectively. It was proved that using TPU as a sublayer results in improving mechanical resistance of the coatings as compared with the pure silica nanocoating. Moreover, the samples showed an excellent resistance against elevated temperatures (150 °C) and remained superhydrophobic; however, further increment of the annealing temperatures to 200 °C caused the TPU macromolecules to migrate onto the top layer of the coatings significantly reducing the water repellency, which was visually proved by SEM.

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

    NASA Astrophysics Data System (ADS)

    Czvikovszky, T.; Hargitai, H.

    1997-08-01

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

  10. Polymer nanocomposites based on P3OT, TPU and SWNT: preparation and characterization

    Microsoft Academic Search

    Glaura G. Silva; Hallen D. R. Calado; Anthony W. Musumeci; Wayde Martens; Eric R. Waclawik; Ray L. Frost; Graeme A. George

    2009-01-01

    Single walled carbon nanotubes (SWNTs) were incorporated in polymer nanocomposites based on poly(3- octylthiophene) (P3OT), thermoplastic polyurethane (TPU) or a blend of them. Thermogravimetry demonstrated the success of the purification procedure employed in the chemical treatment of SWNTs prior to composite preparation. Stable dispersions of SWNTs in chloroform were obtained by non-covalent interactions with the dissolved polymers. Composites exhibited glass

  11. Development of Expanded Thermoplastic Polyurethane Bead Foams and Their Sintering Mechanism

    NASA Astrophysics Data System (ADS)

    Hossieny, Nemat

    Polymer bead foaming technology represents a breakthrough in the production of low density plastic foamed components that have a complex geometrical structure and has helped to expand the market for plastic foams by broadening their applications. In this research, the unique microstructure of thermoplastic polyurethane (TPU) consisting of phase-separated hard segment (HS) domains dispersed in the soft segment (SS) matrix has been utilized to develop expanded TPU (E-TPU) bead foam with microcellular morphologies and also to create inter-bead sintering into three dimensional products using steam-chest molding machine. The phase-separation and crystallization behavior of the HS chains in the TPU microstructure was systematically studied in the presence of dissolved gases and also by changing the microstructure of TPU by melt-processing and addition of nano-/micro-sized additives. It was observed that the presence of gas improved the phase separation (i.e. crystallization) of HSs and increased the overall crystallinity of the TPU. It was also shown that by utilizing the HS crystalline domains, the overall foaming behavior of TPU (i.e. cell nucleation and expansion ratio) can be significantly improved. Moreover, the HS crystalline domains can be effective for both sintering of the beads as well strengthening the individual beads to improve the property of the moulded part. It was also observed that unlike other polymer bead foaming technologies, the E-TPU bead foaming sintering does not require formation of double melting-peak. The original broad melting peak existing in the TPU microstructure due to the wide size distribution of HS crystallites can be effectively utilized for the purpose of sintering as well as maintenance of the overall dimensional stability of the moulded part.

  12. Temperature dependence of the thermoplastic formability in bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Bryn Pitt, E.; Kumar, Golden; Schroers, Jan

    2011-08-01

    The temperature dependence of the maximum strain a bulk metallic glass (BMG) can undergo in its supercooled liquid state under specified conditions is determined. This formability is measured experimentally over a wide temperature range using Zr35Ti30Cu8.25Be26.75 as an example BMG. When considering five different BMG formers, we found that the formability continuously increases with temperature. This behavior is ubiquitous among BMGs whose crystallization behavior can be described by steady state nucleation and diffusion limited growth. Therefore, in order to maximize the formability during thermoplastic forming of BMGs, the highest processing temperature should be chosen at which crystallization can still be avoided.

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  14. Heat flow analysis in connection with thermoplastic filament winding

    NASA Astrophysics Data System (ADS)

    Brage, Anders; Lamrell, Charles

    1988-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M. (inventor)

    1983-01-01

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

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

    PubMed

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

    2006-07-26

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

  17. Stress-induced structural changes in thermoplastic composites

    SciTech Connect

    Kitano, A.

    1991-01-01

    Polymeric Composites: Cyclic stress effects on PEEK (Poly-ether-ether-ketone) matrix thermoplastic composite system were examined by thermal-analysis techniques: DSC (Differential Scanning Calorimeter), DMA (Dynamic Mechanical Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), DGT (Density Gradient Technique), and WAXS (Wide angle X-ray Scattering). These measurements identified for the first time stress-induced crystallization of PEEK below the glass transition temperature (Tg). Also, PEEK crystallization above T[sub g] was kinetically studied by DSC and DMA, and a previously developed dual-crystallization methodology was extended to account for the influence of stress on crystallization. Finally, a fatigue kinetic model for un-notched PEEK films and a crack propagation model for PEEK composites were also developed providing a relation between matrix morphology and end-use performance. Collectively, this work established the importance of structural changes in thermoplastic-based composites that can be both monitored and influenced by dynamic (cyclic) mechanical experiments.

  18. Advanced Laser Transmission Welding Strategies for Fibre Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

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

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

  19. CREEP MODELING FOR INJECTION-MOLDED LONG-FIBER THERMOPLASTICS

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

    2008-06-30

    This paper proposes a model to predict the creep response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the nonlinear viscoelastic behavior described by the Schapery’s model. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber length and orientation distributions were measured and used in the analysis that applies the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption (termed as the Eshelby-Mori-Tanaka approach) and the fiber orientation averaging technique to compute the overall strain increment resulting from an overall constant applied stress during a given time increment. The creep model for LFTs has been implemented in the ABAQUS finite element code via user-subroutines and has been validated against the experimental creep data obtained for long-glass-fiber/polypropylene specimens. The effects of fiber orientation and length distributions on the composite creep response are determined and discussed.

  20. Refractive index modification of polymers using nanosized dopants

    NASA Astrophysics Data System (ADS)

    Hanemann, Thomas; Boehm, Johannes; Müller, Claas; Ritzhaupt-Kleissl, Eberhard

    2008-04-01

    The addition of nanosized inorganic or organic dopants to polymers allows the modification of the polymers physical properties enabling the realization of functionalized polymers with new application fields e.g. in microoptics. Exemplarily electron rich organic dopants, solved in polymers, cause a pronounced increase of the refractive index. Polymer based reactive resins like PMMA, solved in MMA, or unsaturated polyester, solved in styrene, can be cured to thermoplastic polymers. The resin's low viscous flow behaviour enables an easy composite formation by solving the organic dopants in the liquid up to a dopant content of 50 wt%, followed by solidification to a thermoplastic. The addition of simple organic molecules like phenanthrene or benzochinoline allows a refractive index elevation at 633 nm from 1.56 up to 1.60 retaining the good transmission properties. In comparison the refractive index of PMMA can be increased from the initial value of 1.49 up to values around 1.58 (@633 nm). All composites show an almost linear correlation between dopant content and refractive index. Using these composites devices like 3dB-couplers or an electrooptical modulator applying injection molded or hot embossed substrates have been realized.

  1. Dielectric Characterization of PCL-Based Thermoplastic Materials for Microwave Diagnostic and Therapeutic Applications

    PubMed Central

    Aguilar, Suzette M.; Shea, Jacob D.; Al-Joumayly, Mudar A.; Van Veen, Barry D.; Behdad, Nader; Hagness, Susan C.

    2011-01-01

    We propose the use of a polycaprolactone (PCL)-based thermoplastic mesh as a tissue-immobilization interface for microwave imaging and microwave hyperthermia treatment. An investigation of the dielectric properties of two PCL-based thermoplastic materials in the frequency range of 0.5 – 3.5 GHz is presented. The frequency-dependent dielectric constant and effective conductivity of the PCL-based thermoplastics are characterized using measurements of microstrip transmission lines fabricated on substrates comprised of the thermoplastic meshes. We also examine the impact of the presence of a PCL-based thermoplastic mesh on microwave breast imaging. We use a numerical test bed comprised of a previously reported three-dimensional anatomically realistic breast phantom and a multi-frequency microwave inverse scattering algorithm. We demonstrate that the PCL-based thermoplastic material and the assumed biocompatible medium of vegetable oil are sufficiently well matched such that the PCL layer may be neglected by the imaging solution without sacrificing imaging quality. Our results suggest that PCL-based thermoplastics are promising materials as tissue immobilization structures for microwave diagnostic and therapeutic applications. PMID:21622068

  2. Graphene/Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Macosko, Chris

    2010-03-01

    Graphite has attracted large attention as a reinforcement for polymers due to its ability to modify electrical conductivity, mechanical and gas barrier properties of host polymers and its potentially lower cost than carbon nanotubes. If graphite can be exfoliated into atomically thin graphene sheets, it is possible to achieve the highest property enhancements at the lowest loading. However, small spacing and strong van der Waals forces between graphene layers make exfoliation of graphite via conventional composite manufacturing strategies challenging. Recently, two different approaches to obtain exfoliated graphite prior to blending were reported: thermal treatment (Schniepp et al., JACS 2006) and chemical modification (Stankovich et al., J Mat Chem 2006). Both start from graphite oxide. We will describe and evaluate these exfoliation approaches and the methods used to produce graphene reinforced thermoplastics, particularly polyester, polycarbonate and polyurethane nanocomposites. Three different dispersion methods - melt blending, solution mixing and in-situ polymerization -- are compared. Characterization of dispersion quality is illustrated with TEM, rheology and in electrical conductivity, tensile modulus and gas barrier property improvement.

  3. Polymer films

    DOEpatents

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

    2008-12-30

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

  4. Chelating efficiency and thermal, mechanical and decay resistance performances of chitosan copper complex in wood–polymer composites

    Microsoft Academic Search

    John Z. Lu; Xinfang Duan; Qinglin Wu; Kun Lian

    2008-01-01

    Wood–polymer composites (WPC) have been extensively used for building products, outdoor decking, automotive, packaging materials, and other applications. WPC is subject to fungal and termite attacks due to wood components enveloped in the thermoplastic matrix. Much effort has been made to improve decay resistance of WPC using zinc borate and other chemicals. In this study, chitosan copper complex (CCC) compounds

  5. Analytical and experimental evaluation of techniques for the fabrication of thermoplastic hologram storage devices

    NASA Technical Reports Server (NTRS)

    Rogers, J. W.

    1975-01-01

    The results of an experimental investigation on recording information on thermoplastic are given. A description was given of a typical fabrication configuration, the recording sequence, and the samples which were examined. There are basically three configurations which can be used for the recording of information on thermoplastic. The most popular technique uses corona which furnishes free charge. The necessary energy for deformation is derived from a charge layer atop the thermoplastic. The other two techniques simply use a dc potential in place of the corona for deformation energy.

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

    SciTech Connect

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

    2000-01-01

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

  7. Review on ultrasonic fabrication of polymer micro devices.

    PubMed

    Sackmann, J; Burlage, K; Gerhardy, C; Memering, B; Liao, S; Schomburg, W K

    2015-02-01

    Fabrication of micro devices from thermoplastic polymers by ultrasonic processing has become a promising new technology in recent years. Microstructures are generated on polymer surfaces with cycle times of a few seconds and are tightly sealed in even shorter times. Investment costs and energy consumption are comparatively low and processes are very flexible enabling economic fabrication even for small-scale production. For large-scale production role-to-role fabrication has been shown reducing costs even more. A variety of micro devices have been introduced up to now mostly for microfluidic applications. Besides this, electronic circuit boards are fabricated by ultrasonic processing. PMID:25213312

  8. EXPERIMENTAL IDENTIFICATION OF FATIGUE DAMAGE MODEL FOR SHORT GLASS FIBRE REINFORCED THERMOPLASTIC COMPOSITES

    Microsoft Academic Search

    H. Nouri; H. Chalal; F. Meraghni; P. Lory

    A polycyclic fatigue damage model for short glass fibre reinforced thermoplastics is developed and implemented into ABAQUS FE code using UMAT subroutine. The MNL model is introduced here in terms of damage rates:

  9. Processing Optimization of Deformed Plain Woven Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    Smith, John R.; Vaidya, Uday K.

    2013-12-01

    This research addresses the processing optimization of post-manufactured, plain weave architecture composite panels consisted of four glass layers and thermoplastic polyurethane (TPU) when formed with only localized heating. Often times, during the production of deep drawn composite parts, a fabric preform experiences various defects, including non-isothermal heating and thickness variations. Minimizing these defects is of utmost importance for mass produceability in a practical manufacturing process. The broad objective of this research was to implement a design of experiments approach to minimize through-thickness composite panel variation during manufacturing by varying the heating time, the temperature of heated components and the clamping pressure. It was concluded that the heated tooling with least area contact was most influential, followed by the length of heating time and the amount of clamping pressure.

  10. Modeling Fatigue Damage in Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

    2009-10-30

    This paper applies a fatigue damage model recently developed for injection-molded long-fiber thermoplastics (LFTs) to predict the modulus reduction and fatigue lifetime of glass/polyamide 6,6 (PA6,6) specimens. The fatigue model uses a multiscale mechanistic approach to describe fatigue damage accumulation in these materials subjected to cyclic loading. Micromechanical modeling using a modified Eshelby-Mori-Tanaka approach combined with averaging techniques for fiber length and orientation distributions is performed to establish the stiffness reduction relation for the composite as a function of the microcrack volume fraction. Next, continuum damage mechanics and a thermodynamic formulation are used to derive the constitutive relations and the damage evolution law. The fatigue damage model has been implemented in the ABAQUS finite element code and has been applied to analyze fatigue of the studied glass/PA6,6 specimens. The predictions agree well with the experimental results.

  11. Analysis of a space-exposed thermoplastic resin

    NASA Technical Reports Server (NTRS)

    Young, Philip R.; Slemp, Wayne S.; Siochi, Emilie J.; Davis, Judith R. J.

    1992-01-01

    The chemical characterization of a thermoplastic resin exposed to the low Earth orbit (LEO) environment for 10 months and for 5.8 years is reported. The resin, processed as a thick film and as a matrix for a graphite fiber reinforced composite, few exposed in the RAM direction on the NASA Long Duration Exposure Facility (LDEF). Differences attributable to environmental exposure were detected in infrared spectra and in various molecular weight parameters of film after 10 months in LEO. Those effects were not as apparent in composites after 5.8 years in LEO. Increased exposure to atomic oxygen toward the end of the LDEF mission probably scrubbed these effects from specimens exposed for 5.8 years. The intent of this study is to increase our fundamental understanding of space environmental effects on polymeric materials and to develop a benchmark for enhancing our methodology for and understanding of the ground-based simulation of space environmental effects.

  12. An automated technique for manufacturing thermoplastic stringers in continuous length

    NASA Astrophysics Data System (ADS)

    Pantelakis, Sp.; Baxevani, E.; Spelz, U.

    In the present work an automated Continuous Compression Moulding Technique for the manufacture of stringers in continuous length is presented. The method combines pultrusion and hot-pressing. The technique is utilized for the production of L-shape stringers which are widely applied in aerospace constructions. The investigation was carried out on carbon reinforced PEEK (C/PEEK), as well as, for comparison, on the thermoplastic composites carbon reinforced polyethersulfon (C/PES), glass and carbon reinforced polyphenylene-sulfide (G/PPS, C/PPS) and Kevlar reinforced Polyamide 6 (K/PA 6). For the materials investigated the optimized process parameters for manufacturing the L-shape stringers were derived experimentally. To achieve this goal, the quality of the produced parts was controlled by using non-destructive testing techniques. Parts providing satisfactory quality were also tested destructively to measure their mechanical properties. The investigation results have shown the suitability of the technique to produce continuous length stringers.

  13. Monitoring the resistance welding of thermoplastic composites through acoustic emission

    NASA Astrophysics Data System (ADS)

    D'Antonio, Luigi; Sabatino, Claudio; Ortona, Alberto; Gillespie, John W., Jr.

    This paper investigates the monitoring of thermoplastic composite's resistance welding through acoustic emission. An amorphous bonding technique (Thermobond TM) is used to join AS4 graphite fiber reinforced polyetheretherketone (APC2). By placing acoustic emission sensors next to the weld region, the influence of welding parameters on the acoustic emission output was determined. Discrete parameters as well as complete waveforms were acquired through dedicated hardware and software. Results indicate a strong relationship between acoustic phenomena and welding history. Experimental observations show that change in the cumulative representation of some discrete parameters (ring down counts in the case under study) occurs at the glass transition temperature of the PEI that was comolded on the surface of the parts. The ability to correlate AE with process conditions, quality, and performance gives rise to the potential for further automation and control of the resistance welding process through on-line acoustic measurements.

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

    NASA Astrophysics Data System (ADS)

    Iannone, Michele; Esposito, Floriana; Cammarano, Aniello

    2014-05-01

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

  15. Thermoplastic properties of coal at elevated pressures: effects of gas atmospheres

    SciTech Connect

    Khan, M.R.; Jenkins, R.G.

    1985-01-01

    Thermoplastic properties of a Lower Kittanning seam coal have been characterized at a range of gas atmospheres (He, H/sub 2/, N/sub 2/, Ar, and CO/sub 2/). The results suggest that the thermoplastic properties of coal can vary markedly in various gases. At elevated pressures of CO/sub 2/, coals, and porous carbonaceous materials undergo expansion which leads to irreversible structural changes. 11 refs., 5 figs.

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

    SciTech Connect

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

    2007-01-01

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7 mm (1/2 in.) using equipment optimized for molding short fiber reinforced thermoplastics.

  17. LONG-FIBER THERMOPLASTIC INJECTION MOLDED COMPOSITES: FROM PROCESS MODELING TO PROPERTY PREDICTION1

    Microsoft Academic Search

    Ba Nghiep Nguyen; James D Holbery; Kenneth I Johnson; Mark T Smith

    Recently, long-fiber filled thermoplastics have attracted great interest within the automotive industry since these materials offer much better structural performance (e.g. higher elastic moduli, strength, and durability) than their short-fiber analogues, and they can be processed through injection molding with some specific tool design. However, in order that long-fiber thermoplastic injection molded composites can be used efficiently for automotive applications,

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

    Microsoft Academic Search

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

    2008-01-01

    This paper applies a recently developed model to predict the elastic-plastic stress\\/strain response and strength of injection-molded long-fiber thermoplastics (LFTs). The model combines a micro-macro constitutive modeling approach with experimental characterization and modeling of the composite microstructure to determine the composite stress\\/strain response and strength. Specifically, it accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic

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

    NASA Astrophysics Data System (ADS)

    Warren, Paul B.

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  2. Ceramic coatings on polymers by high energy beam for tribology application

    SciTech Connect

    Ayrault, S. [Lyon 1 Univ., Villeurbanne (France). Lab. d`Etudes des Materiaux Plastiques et des Biomateriaux; [CALFETMAT, Ecully (France). Lab. Materiaux-Mecanique- Physique; Chabert, B.; Soulier, J.P. [Lyon 1 Univ., Villeurbanne (France). Lab. d`Etudes des Materiaux Plastiques et des Biomateriaux; Treheux, D.; Vannes, A.B. [CALFETMAT, Ecully (France). Lab. Materiaux-Mecanique-Physique; Chevallier, P.

    1995-10-01

    Aluminum oxide powder has been deposited on a thermoplastic polymer (PET) using atmospheric plasma and laser (CO{sub 2}, {lambda} = 10.6 {micro}m). The results have shown that there exists a mechanical anchorage of ceramic on the surface of the polymer whatever the technique used with different ceramic structures. To characterize the ceramic coating, two techniques have been used by tribological solicitation with little displacement (fretting) and by erosion. In this case, ceramic influence on the surface has been noted like protective substance in addition to the polymer structure interaction.

  3. Flow properties of a series of experimental thermoplastic polymides

    NASA Technical Reports Server (NTRS)

    Burks, H. D.; Nelson, J. B.; Price, H. L.

    1981-01-01

    The softening temperature to degradation temperature range of the polymers was about 440 to 650 K. All of the polymers retained small amounts of solvent as indicated by an increase in T(sub g) as the polymers were dried. The flow properties showed that all three polymers had very high apparent viscosities and would require high pressures and/or high temperatures and/or long times to obtain adequate flow in prepregging and molding. Although none was intended for such application, two of the polymers were combined with carbon fibers by solution prepregging. The prepregs were molded into laminates at temperatures and times, the selection of which was guided by the results from the flow measurements. These laminates had room temperature short beam shear strength similar to that of carbon fiber laminates with a thermosetting polyimide matrix. However, the strength had considerable scatter, and given the difficult processing, these polymides probably would not be suitable for continuous fiber composites.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  5. Large-Strain Transparent Magnetoactive Polymer Nanocomposites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    2012-01-01

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

  6. Comparison of Piezoresistive Monofilament Polymer Sensors

    PubMed Central

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

    2014-01-01

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

  7. SUPER HARD SURFACED POLYMERS

    SciTech Connect

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

    2010-01-01

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

  8. Thermoplastic Starch Films with Vegetable Oils of Brazilian Cerrado

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

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

    PubMed

    Dang, Khanh Minh; Yoksan, Rangrong

    2015-01-22

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  12. Mechanical, morphological and thermal properties of in situ ternary composites based on poly(ether imide), silicone rubber and liquid crystalline polymer

    Microsoft Academic Search

    T. Rath; S. Kumar; R. N. Mahaling; B. B. Khatua; C. K. Das; S. B. Yadaw

    2008-01-01

    A compatibilization method for improving the mechanical and thermal properties of thermoplastic\\/thermotropic liquid crystalline polymer (LCP) blends has been tested in blends of poly(ether imide), PEI, with a thermotropic copolyester (Vectra B-950). It is based on the addition of a third component, a functionalized elastomer (hydroxy terminated silicone rubber), to the blend that interacts with the matrix polymer and the

  13. Microgravity Polymers

    NASA Technical Reports Server (NTRS)

    1986-01-01

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

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

    E-print Network

    Whalen, Casey Allen

    2012-02-14

    and analyzed. Results for the CP2 nano-composites showed that during the cure phase, the NiNS settled to the bottom of the films resulting in a non-dispersed composite. This result highlighted the difference between NiNS and other more conventional nano-particles...

  15. Adhesion study of thermoplastic polyimides with Ti-6Al-4V alloy and PEEK-graphite composites

    SciTech Connect

    Yoon Taeho.

    1991-01-01

    High glass transition (e.g. 360C) melt processable thermoplastic polyimide homopolymers and poly(imide-siloxane) segmented copolymers were prepared from a number of diamines and dianhydrides via solution imidization, polydimethylsilxane segment incorporation and molecular weight control with non-reactive phthalimide end-groups. The adhesive bond performance of these polyimides was investigated as a function of molecular weight, siloxane incorporation, residual solvent, test temperature, and polyimide structure via single-lap shear samples prepared from treated Ti-6Al-4V alloy adherends and compression-molded film adhesives of scrim-cloth adhesives. The adhesive bond strengths increased greatly with siloxane-segment incorporation at 10, 20 and 30 wt% and decreased slightly with total polymer molecular weight. As the test temperature was increased, adhesive bond strength increased, decreased or showed a maximum at some temperatures depending on the polyimide structure and siloxane content. The poly(imide-30% siloxane) segmented copolymer and a miscible poly(ether-imide) also demonstrated excellent adhesive bond strength with poly(arylene ether ketone) PEEK{reg sign}-graphite composites.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  17. Self-Healing Polymers and Composites

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

  18. Self-healing Polymers and Composites

    SciTech Connect

    Blaiszik, B. J. [Beckman Inst. for Advanced Science and Technology, Univ. of Illinois, Urbana, IL (United States); Kramer, S. L. B. [Beckman Inst. for Advanced Science and Technology, Univ. of Illinois, Urbana, IL (United States); Olugebefola, S. C. [Beckman Inst. for Advanced Science and Technology, Univ. of Illinois, Urbana, IL (United States); Moore, J. S. [Beckman Inst. for Advanced Science and Technology, Univ. of Illinois, Urbana, IL (United States); Sottos, Nancy R. [Beckman Inst. for Advanced Science and Technology, Univ. of Illinois, Urbana, IL (United States); White, Scott R. [Beckman Inst. for Advanced Science and Technology, Univ. of Illinois, Urbana, IL (United States)

    2010-06-01

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

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

    Microsoft Academic Search

    S. D. Mookhoek

    2010-01-01

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

  20. A biomimic shape memory polymer based self-healing particulate composite

    Microsoft Academic Search

    Jones Nji; Guoqiang Li

    2010-01-01

    In a previous study, a biomimic two-step self-healing scheme (close-then-heal (CTH)) by mimicking human skin has been proposed for self-healing structural-length scale damage [Li and Uppu. Composites Science and Technology 2010; 70: 1419–1427]. The purpose of this study is to validate this idea by fabricating a composite with thermoplastic particles (Copolyster) dispersed in a shape memory polymer matrix (Veriflex Polystyrene).

  1. Finite element analysis of an inelastic interface in ultrasonic welded metal\\/fibre-reinforced polymer joints

    Microsoft Academic Search

    N. Konchakova; F. Balle; F. J. Barth; R. Mueller; D. Eifler; P. Steinmann

    2010-01-01

    The ultrasonic welding technology is an innovative method to produce hybrid joints for multi-material components. In this contribution, the behaviour of an interface layer of metal\\/fibre-reinforced polymer single overlap tensile specimens is considered. The investigations are carried out using the ultrasonic metal welding technique (UMW) for joining carbon fibre reinforced thermoplastic composites (CFRP) with aluminium alloys. An interfacial traction-separation-law based

  2. Polymers Presentation

    NSDL National Science Digital Library

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

  3. Influence of thickness and undercut of thermoplastic resin clasps on retentive force.

    PubMed

    Osada, Hidekazu; Shimpo, Hidemasa; Hayakawa, Tohru; Ohkubo, Chikahiro

    2013-01-01

    Thermoplastic resin clasps have been used for esthetic denture rehabilitation. However, details of the design of the clasps have never been thoroughly clarified. This study investigated the retentive forces of thermoplastic resin clasps for non-metal clasp dentures. The retentive forces of all thermoplastic resin clasps depended on the elastic modulus of each resin, undercuts, thickness, and widths of the tested. A clasp with more than 0.5 mm undercut and 1.0 mm thickness is needed for Valplast. Similarly, more than 0.25 mm undercut and 1.0 mm thickness and 0.5 mm undercut and 0.5 mm thickness are required for Estheshot and Reigning, respectively; thus, the recommended clasp arm thickness is 1.0 mm to 1.5 mm for Valplast and Estheshot and 0.5 mm to 1.0 mm for Reigning when the width of the retentive arm is 5.0 mm. PMID:23718997

  4. Solvent resistant thermoplastic aromatic poly(imidesulfone) and process for preparing same

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  6. Tailoring the degradation kinetics of poly(ester-carbonate urethane)urea thermoplastic elastomers for tissue engineering scaffolds

    PubMed Central

    Hong, Yi; Guan, Jianjun; Fujimoto, Kazuro L.; Hashizume, Ryotaro; Pelinescu, Anca L.; Wagner, William R.

    2010-01-01

    Biodegradable elastomeric scaffolds are of increasing interest for applications in soft tissue repair and regeneration, particularly in mechanically active settings. The rate at which such a scaffold should degrade for optimal outcomes, however, is not generally known and the ability to select from similar scaffolds that vary in degradation behavior to allow such optimization is limited. Our objective was to synthesize a family of biodegradable polyurethane elastomers where partial substitution of polyester segments with polycarbonate segments in the polymer backbone would lead to slower degradation behavior. Specifically, we synthesized poly(ester carbonate)urethane ureas (PECUUs) using a blended soft segment of poly(caprolactone) (PCL) and poly(1,6-hexamethylene carbonate) (PHC), a 1,4-diisocyanatobutane hard segment and chain extension with putrescine. Soft segment PCL/PHC molar ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 were investigated. Polymer tensile strengths varied from 14-34 MPa with breaking strains of 660-875%, initial moduli of 8-24 MPa and 100% recovery after 10% strain. Increased PHC content was associated with softer, more distensible films. Scaffolds produced by salt leaching supported smooth muscle cell adhesion and growth in vitro. PECUU in aqueous buffer in vitro and subcutaneous implants in rats of PECUU scaffolds showed degradation slower than comparable poly(ester urethane)urea and faster than poly(carbonate urethane)urea. These slower degrading thermoplastic polyurethanes provide opportunities to investigate the role of relative degradation rates for mechanically supportive scaffolds in a variety of soft tissue repair and reconstructive procedures. PMID:20188411

  7. Morphological control of inter-penetrating polymer networks

    NASA Technical Reports Server (NTRS)

    Hansen, Marion

    1989-01-01

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

  8. Characterization of elastic-viscoplastic properties of an AS4/PEEK thermoplastic composite

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The elastic-viscoplastic properties of an AS4/PEEK (APC-2) thermoplastic composite were characterized at 24 C (75 F) and 121 C (250 F) by using a one-parameter viscoplasticity model. To determine the strain-rate effects, uniaxial tension tests were performed on unidirectional off-axis coupon specimens with different monotonic strain rates. A modified Bodner and Partom's model was also used to describe the viscoplasticity of the thermoplastic composite. The experimental results showed that viscoplastic behavior can be characterized quite well using the one-parameter overstress viscoplasticity model.

  9. [Renewable resource-based composites of thermoplastic acorn starch and polycaprolactone: preparation and FTIR spectrum analysis].

    PubMed

    Li, Shou-Hai; Zhuang, Xiao-Wei; Wang, Chun-Peng; Chu, Fu-Xiang

    2011-04-01

    Acorn starch was used as the main material. Thermoplastic acorn starch (TPAS) and binary composites of thermoplastic acorn starch(TPAS)/Polycaprolactone (PCL) were prepared by hot-melt extrusion method. The effects of different plasticizers such as ethylene glycol, glycerol, monoethanolamine, iminobisetnanol and triethanolamine on molecular structure of samples were studied by FTIR and XRD analysis. In addition, the effects of different plasticizing system on molecular structure and mechanical properties of composites were also studied. The results showed that the addition of plasticizers changed the inter-molecular structure, and glycerol-based TPAS/PCL composites showed favorable mechanical properties. PMID:21714245

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

    SciTech Connect

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

    2014-05-15

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

  11. Characterization of glass-filled engineering thermoplastic composites

    SciTech Connect

    Whitaker, R.B.; Nease, A.B.; Yelton, R.O.

    1983-01-01

    Characterization of three engineering thermoplastic (TP) materials has been carried out to assess suitability for Mound applications: Poly(etheretherketone) (PEEK), Poly(etherimide) (PEI), and Poly(ethersulfone) (PES). Analyses included: thermogravimetric (TG), thermomechanical (TMA), direct probe/mass spectroscopy (DIP/MS), Fourier transform infrared spectroscopy (FT-IR), and other chemical analyses. Both neat and glass-filled PEEK and PES were studied; only unfilled PEI was examined. Thermogravimetric analysis of the three TP's in N/sub 2/ showed that all were greater than or equal to 525/sup 0/C in decomposition onset temperature, with PEEK > PEI > PES. Both glass-filled PEEK and PEI showed <1% weight loss in the melt after two hours (N/sub 2/). TMA analyses were used to determine expansion coefficients below T/sub g/ for all three TP's. The glass-filled PEEK exhibited a low temperature (approx. 60 to 70/sup 0/C) transition below T/sub g/ (approx. 150/sup 0/C) on the first TMA runs. This disappeared on subsequent TMA runs and did not reappear on aging/RT. DIP/MS analyses showed both water and phenyl sulfone to be present in PES and PEEK. Water only was observed in PEI. The presence of phenylsulfone in PEEK was confirmed by FT-IR, and sulfur was found to be present in amounts up to 0.23% in 30% glass-filled molding compounds. Residual polymerization solvent is a probable source. Fluoride (from a monomer in the PEEK polymerization) was also detected.

  12. Biodegradable, thermoplastic polyurethane grafts for small diameter vascular replacements.

    PubMed

    Bergmeister, Helga; Seyidova, Nargiz; Schreiber, Catharina; Strobl, Magdalena; Grasl, Christian; Walter, Ingrid; Messner, Barbara; Baudis, Stefan; Fröhlich, Sophie; Marchetti-Deschmann, Martina; Griesser, Markus; di Franco, Matt; Krssak, Martin; Liska, Robert; Schima, Heinrich

    2015-01-01

    Biodegradable vascular grafts with sufficient in vivo performance would be more advantageous than permanent non-degradable prostheses. These constructs would be continuously replaced by host tissue, leading to an endogenous functional implant which would adapt to the need of the patient and exhibit only limited risk of microbiological graft contamination. Adequate biomechanical strength and a wall structure which promotes rapid host remodeling are prerequisites for biodegradable approaches. Current approaches often reveal limited tensile strength and therefore require thicker or reinforced graft walls. In this study we investigated the in vitro and in vivo biocompatibility of thin host-vessel-matched grafts (n=34) formed from hard-block biodegradable thermoplastic polyurethane (TPU). Expanded polytetrafluoroethylene (ePTFE) conduits (n=34) served as control grafts. Grafts were analyzed by various techniques after retrieval at different time points (1 week; 1, 6, 12 months). TPU grafts showed significantly increased endothelial cell proliferation in vitro (P<0.001). Population by host cells increased significantly in the TPU conduits within 1 month of implantation (P=0.01). After long-term implantation, TPU implants showed 100% patency (ePTFE: 93%) with no signs of aneurysmal dilatation. Substantial remodeling of the degradable grafts was observed but varied between subjects. Intimal hyperplasia was limited to ePTFE conduits (29%). Thin-walled TPU grafts offer a new and desirable form of biodegradable vascular implant. Degradable grafts showed equivalent long-term performance characteristics compared to the clinically used, non-degradable material with improvements in intimal hyperplasia and ingrowth of host cells. PMID:25218664

  13. Laser Transmission Welding of White Thermoplastics with Adapted Wavelengths

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  15. Packaging of Microfluidic Devices for Fluid Interconnection Using Thermoplastics

    Microsoft Academic Search

    D. Patrick Webb; David A. Hutt; Neil Hopkinson; Paul P. Conway; Paul J. Palmer

    2009-01-01

    A new packaging method for microfluidic devices is proposed of polymer over-molding to form a fluidic manifold integrated with the device in a single step. The anticipated advantages of the proposed method of packaging are ease of assembly and low part count, making it suitable for low cost and high volume manufacturing. This paper reports the results of a preliminary

  16. Photoluminescent zinc oxide polymer nanocomposites fabricated using picosecond laser ablation in an organic solvent

    NASA Astrophysics Data System (ADS)

    Wagener, Philipp; Faramarzi, Shamsolzaman; Schwenke, Andreas; Rosenfeld, Rupert; Barcikowski, Stephan

    2011-06-01

    Nanocomposites made of ZnO nanoparticles dispersed in thermoplastic polyurethane were synthesized using picosecond laser ablation of zinc in a polymer-doped solution of tetrahydrofuran. The pre-added polymer stabilizes the ZnO nanoparticles in situ during laser ablation by forming a polymer shell around the nanoparticles. This close-contact polymer shell has a layer thickness up to 30 nm. Analysis of ZnO polyurethane nanocomposites using optical spectroscopy, high resolution transmission electron microscopy and X-ray diffraction revealed that oxidized and crystalline ZnO nanoparticles were produced. Those nanocomposites showed a green photoluminescence emission centred at 538 nm after excitation at 350 nm, which should be attributed to oxygen defects generated during the laser formation mechanism of the monocrystalline nanoparticles. Further, the influence of pulse energy and polymer concentration on the production rate, laser fluence and energy-specific mass productivity was investigated.

  17. SULFUR POLYMER ENCAPSULATION.

    SciTech Connect

    KALB, P.

    2001-08-22

    Sulfur polymer cement (SPC) is a thermoplastic polymer consisting of 95 wt% elemental sulfur and 5 wt% organic modifiers to enhance long-term durability. SPC was originally developed by the U.S. Bureau of Mines as an alternative to hydraulic cement for construction applications. Previous attempts to use elemental sulfur as a construction material in the chemical industry failed due to premature degradation. These failures were caused by the internal stresses that result from changes in crystalline structure upon cooling of the material. By reacting elemental sulfur with organic polymers, the Bureau of Mines developed a product that successfully suppresses the solid phase transition and significantly improves the stability of the product. SPC, originally named modified sulfur cement, is produced from readily available, inexpensive waste sulfur derived from desulfurization of both flue gases and petroleum. The commercial production of SPC is licensed in the United States by Martin Resources (Odessa, Texas) and is marketed under the trade name Chement 2000. It is sold in granular form and is relatively inexpensive ({approx}$0.10 to 0.12/lb). Application of SPC for the treatment of radioactive, hazardous, and mixed wastes was initially developed and patented by Brookhaven National Laboratory (BNL) in the mid-1980s (Kalb and Colombo, 1985; Colombo et al., 1997). The process was subsequently investigated by the Commission of the European Communities (Van Dalen and Rijpkema, 1989), Idaho National Engineering Laboratory (Darnell, 1991), and Oak Ridge National Laboratory (Mattus and Mattus, 1994). SPC has been used primarily in microencapsulation applications but can also be used for macroencapsulation of waste. SPC microencapsulation has been demonstrated to be an effective treatment for a wide variety of wastes, including incinerator hearth and fly ash; aqueous concentrates such as sulfates, borates, and chlorides; blowdown solutions; soils; and sludges. It is not recommended for treatment of wastes containing high concentrations of nitrates because of potentially dangerous reactions between sulfur, nitrate, and trace quantities of organics. Recently, the process has been adapted for the treatment of liquid elemental mercury and mercury contaminated soil and debris.

  18. Piezoelectric Polymers

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  19. Simplified tube models for entangled supramolecular polymers

    NASA Astrophysics Data System (ADS)

    Boudara, Victor; Read, Daniel

    2015-03-01

    This presentation describes current efforts investigating non-linear rheology of entangled, supramolecular polymeric materials. We describe two recently developed models: 1) We have developed a simplified model for the rheology of entangled telechelic star polymers. This is based on a pre-averaged orientation tensor, a stretch equation, and stretch-dependant probability of detachment of the sticker. In both linear and non-linear regimes, we produce maps of the whole parameter space, indicating the parameter values for which qualitative changes in response to flow are predicted. Results in the linear rheology regime are consistent with previous more detailed models and are in qualitative agreement with experimental data. 2) Using the same modelling framework, we investigate entangled linear polymers with stickers along the backbone. We use a set of coupled equations to describe the stretch between each stickers, and use equations similar to our star model for attachment/detachment of the sticky groups. This model is applicable to industrial polymers such as entangled thermoplastic elasomers, or functionalised model linear polymers. The work leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA Grant Agreement No. 607937 (SUPOLEN).

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

    SciTech Connect

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

    2012-01-01

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

  1. Mechanical Properties of Short Polyethylene Terephthalate Fiber-Thermoplastic Polyurethane Composite

    Microsoft Academic Search

    Sunil. K. N. Kutty; Golok. B. Nando

    1993-01-01

    The effect of short polyester terephthalate (PET) fiber loading on the mechanical properties of thermoplastic polyurethane has been studied. Tensile strength and tear strength were increased with fiber loading after an initial reduction up to 10–20 phr. Elongation at break was reduced drastically beyond 10 phr fiber loading. Impact strength registered a reduction with increasing fiber content. Anisotropy in mechanical

  2. Correction of the measurement of fiber length of short fiber reinforced thermoplastics

    Microsoft Academic Search

    Shao-Yun Fu; Yiu-Wing Mai; Emma Chui-Yee Ching; Robert K. Y Li

    2002-01-01

    Short fiber reinforced thermoplastics are often made using extrusion compounding and injection moulding techniques. Fiber breakage takes place during processing. In finished fiber reinforced parts, there often exists a fiber length distribution. Measurement of fiber length is often performed on photographs of short fibers obtained from burning off or dissolving the matrix. However, relatively long fibers crossing the photographs cannot

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

    EPA Science Inventory

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

  4. Studies on a Novel Thermoplastic Polyurethane as a Binder for Extruded Composite Propellants

    Microsoft Academic Search

    K. S. Mulage; R. N. Patkar; V. D. Deuskar; S. M. Pundlik; S. D. Kakade; M. Gupta

    2007-01-01

    Extruded composite propellant (ECP) is an entirely new thrust area in the development of composite propellants within India. These are based on high-density thermoplastic elastomers as a propellant binder with ammonium perchlorate (AP) as an oxidizer and aluminum (Al) as a metallic fuel. Thus, this class of propellant not only provides higher energy but also yields higher density impulse. There

  5. Investigation of the degradation of thermoplastic polyurethane reinforced with short fibres

    Microsoft Academic Search

    Ronaldo A. Corrêa; Regina C. R. Nunes; Vera L. Lourenço

    1996-01-01

    The thermal behaviour of short fibre reinforced composites was studied by DSC and TGA techniques. A thermoplastic polyurethane elastomer was used as the matrix and carbon fibre or aramid fibre as reinforcing fillers in each composite. The influence of short fibres on the thermal resistance of the matrix, glass transition temperature and kinetic parameters of the degradation reaction of the

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

    E-print Network

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

  7. Flexural, impact and compressive properties of a rigid-thermoplastic matrix\\/cellulose fiber reinforced composites

    Microsoft Academic Search

    G Canché-Escamilla; J Rodriguez-Laviada; J. I Cauich-Cupul; E Mendizábal; J. E Puig; P. J Herrera-Franco

    2002-01-01

    The mechanical behavior of rigid-thermoplastic matrix–cellulose fiber reinforced composites is investigated. These materials exhibit a brittle behavior, that is, they possess a high modulus and therefore, a very limited amount of deformation to fracture. Such behavior makes the characterization of interfacial properties difficult to evaluate. In this paper, the flexural, impact and compressive behavior of cellulose fibers reinforced polymeric matrices,

  8. Use of block copolymers to control the morphologies and properties of thermoplastic\\/thermoset blends

    Microsoft Academic Search

    E. Girard-Reydet; H. Sautereau; J. P. Pascault

    1999-01-01

    A new method for increasing fracture toughness of brittle thermoplastic-modified thermosets by using triblock copolymers has been successfully investigated. The selected systems were polyphenylene ether (PPE)- and polyetherimide (PEI)-modified epoxy networks. Our choice was restricted to available commercial copolymers possibly with some chemical modifications. PPE presents the substantial advantage of having a negative enthalpy of mixing with polystyrene. The maleic

  9. A small area XPS study of the fracture surface of a thermoplastic-modified CFRP

    Microsoft Academic Search

    P. E. Vickers; M. F. Fitzpatrick; L. Boniface; J. F. Watts

    2001-01-01

    Small area XPS at a spatial resolution of 30 µm has been used to study the heterogeneity of the fracture surface of a carbon fibre\\/epoxy composite with thermoplastic PEEK particles incorporated at the interlaminar boundary. Strong evidence was found for a chemical interaction between the PEEK particles and the matrix, in particular the curing agent. Careful charge compensation was required,

  10. Large?scale Experimental Study on the Effects of Flooring Materials on Combustion Behavior of Thermoplastics

    Microsoft Academic Search

    Qiyuan Xie; Heping Zhang; Liang Xu

    2008-01-01

    The effects of flooring materials on the combustion behavior of thermoplastics is investigated. Based on the ISO 9705 fire test setup, an experimental rig was designed. Full?scale experiments of PP combustion were carried out using five flooring boards, namely gypsum, steel, wood, ceramic tile and PVC. The experimental results indicate that the flooring boards play an important role in the

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

    Microsoft Academic Search

    Vlastimil Kunc; Barbara Frame; Ba Nghiep Nguyen; Charles L. Tucker; Gregorio Velez-Garcia

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7

  12. Crystallinity Effects on Fracture of Rings Made of Thermoplastic Powder Impregnated Carbon or Glass Fiber Composites

    Microsoft Academic Search

    M. Evstatiev; K. Friedrich; S. Fakirov

    1993-01-01

    Effects of the supermolecular structure of a thermoplastic matrix on the flexural response of glass (GF) or carbon fiber (CF)\\/polyamide 12 (PA 12) composite rings were investigated. An additional attempt was made to determine their interlaminar mode I fracture energy. Specimen rings were prepared by dry winding of carbon or glass fibers bundles, interspersed with polyamide powder and surrounded by

  13. Effect of insert temperature on integrity of a thermoplastic circuit board

    Microsoft Academic Search

    Hrushikesh Abhyankar; D. Patrick Webb; David A. Hutt

    2010-01-01

    At Loughborough University an environmentally friendly manufacturing process for electronic circuits, involving the embedding of electronic components in thermoplastic resins via insert injection moulding, is under development. Once embedded, interconnection between components is achieved by subsequently plating or printing metallisation patterns on the moulding surface. The environmental benefits of the process arise from the enhanced separability of components, metals and

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

    Microsoft Academic Search

    H. Nouri; F. Meraghni; P. Lory

    2009-01-01

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

  15. Micromechanical modeling of short glass-fiber reinforced thermoplastics-Isotropic damage of pseudograins

    Microsoft Academic Search

    S. Kammoun; L. Brassart; G. Robert; I. Doghri; L. Delannay

    2011-01-01

    A micromechanical damage modeling approach is presented to predict the overall elasto-plastic behavior and damage evolution in short fiber reinforced composite materials. The practical use of the approach is for injection molded thermoplastic parts reinforced with short glass fibers. The modeling is proceeded as follows. The representative volume element is decomposed into a set of pseudograins, the damage of which

  16. Influence of interaction promoter on the properties of thermoplastic elastomeric blends of natural rubber and polyethylene

    Microsoft Academic Search

    Namita Roy Choudhury; Anil K. Bhowmick

    1988-01-01

    The influence of a third component as interaction promoter on the properties of natural rubber-polyethylene thermoplastic blends, both uncured and cured, has been studied. The third component chosen has some structural similarity with polyethylene and is amorphous in nature. Ethylene propylene diene (EPDM) rubber, chlorinated polyethylene and chlorosulphonated polyethylene have been used as the third component. All the third components

  17. Linear viscoelastic properties of olefinic thermoplastic elastomer blends: melt state properties

    Microsoft Academic Search

    W. G. F. Sengers; P. Sengupta; J. W. M. Noordermeer; S. J. Picken; A. D. Gotsis

    2004-01-01

    The linear viscoelastic properties of two types of olefinic thermoplastic elastomer blends were studied using dynamic rheology. The first type consists of a blend of PP, SEBS and oil and has a co-continuous morphology. The second type consists of vulcanised EPDM particles dispersed in a PP matrix. The dynamic rheological behaviour of the blends is a weighted contribution of the

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

    SciTech Connect

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

    2011-04-01

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

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

    EPA Science Inventory

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

  20. Effect of addition of carbon nanofibers and carbon nanotubes on properties of thermoplastic biopolymers

    Microsoft Academic Search

    M. D. Sanchez-Garcia; J. M. Lagaron; S. V. Hoa

    2010-01-01

    This paper presents the properties of nano-bio-composites of solvent cast polyhydroxybutyrate-co-valerate (PHBV) and polycaprolactone (PCL) containing carbon nanofiber or carbon nanotubes as a function of filler content. It is found that carbon nanotubes and nanofibers can be used to enhance the conductivity, thermal, mechanical and to enhance gas barrier properties of thermoplastic biopolyesters.

  1. Synthesis of APA6 thermoplastic matrices for the manufacture of greencomposites

    NASA Astrophysics Data System (ADS)

    Alfonso, A.; Andrés, J.; García-Manrique, J. A.

    2012-04-01

    The present research work assesses the manufacture of long fiber thermoplastic matrix composite materials (GreenComposites). Thermoplastic matrices are too viscous to be injected into the conventional LCM (Liquid Comopsite Molding) molds, and then epoxy, polyester o vinylester resins are used. Nevertheless, the groundbreaking anionic polymerization of ?-caprolactam allows such a synthesis of a thermoplastic APA6 matrix inside the mold. This matrix is sintered from the starting monomers, and presents high mechanical performance and recyclability. In order to do the reactive injection in a LCM mold, it is necessary to control the polymerization mechanism of such a thermoplastic matrix. Likewise, it puts special emphasis on detecting and solving all problems which arose during synthesis. For instance, moisture values were assessed for all starting reactants, since humidity keeps polymerization from occurring. It is thought that once the synthesis and the resulting material characterization are well controlled, the manufacture of GreenComposites through monomers injection and in situ polymerization, as well as addition of state-of-the-art fabrics such as basalt, can proceed successfully.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  3. Large-strain, rigid-to-rigid deformation of bistable electroactive polymers

    NASA Astrophysics Data System (ADS)

    Yu, Zhibin; Yuan, Wei; Brochu, Paul; Chen, Bin; Liu, Zhitian; Pei, Qibing

    2009-11-01

    Thermoplastic poly(tert-butyl acrylate) (PTBA) is reported as an electroactive polymer that is rigid at ambient conditions and turns into a dielectric elastomer above a transition temperature. In the rubbery state, a PTBA thin film can be electrically actuated to strains up to 335% in area expansion. The calculated actuation pressure is 3.2 MPa. The actuation is made bistable by cooling to below glass transition temperature. The PTBA represents the bistable electroactive polymer (BSEP) that can be actuated to various largely strained, rigid shapes. The application of the BSEP for refreshable Braille display, an active tactile display, is also demonstrated.

  4. Polymer brushes

    Microsoft Academic Search

    S. T. MILNER

    1991-01-01

    Polymers attached by one end to an interface at relatively high coverage stretch away from the interface to avoid overlapping, forming a polymer brush. This simple picture may serve as the basis for models in diverse interfacial systems in polymer science, such as polymeric surfactants, stabilized suspensions of colloidal particles, and structures formed by block copolymers. The structure and dynamics

  5. Development of thermoplastic composite tubes for large deformation

    NASA Astrophysics Data System (ADS)

    Derisi, Bijan

    Composites have proved their great potentials for many aerospace applications, where the high performance can justify the high cost. However, the brittleness of the composites has been a main drawback for many applications that require large deformation, high failure strain and extensive energy absorption before final fracture. The objective of this research is to present a solution to the brittleness of the composites in tubular form and to introduce a composite tube that shows the same strength, stiffness and failure strain as its high grade Aluminum 7075-T6 counterpart tube. One application of this research can be in the development of composite landing gear for helicopters. Up to date, almost all helicopter landing gears are made of high strength aluminum, and despite their major issues in maintenance and fabrication, aluminum landing gears have remained the only choice for the helicopter manufacturing industry. Substitution of aluminum landing gear for helicopters with a thermoplastic composite landing gear is really a challenge, but if this can be done, it would be for the first time in the world! Through this research, the mechanical behavior of flat plate Carbon AS4/PEKK is characterized, and the potential mechanisms for large deformation of composite laminates are sought. The outcomes are used to design a composite tube that shows the same strength, stiffness and deformability as its high grade aluminum counterpart. The accuracy of the design is verified through progressive failure by ANSYS analysis and experimental work. Strain Controlled Design is introduced as a new design technique to substitute for the traditional stiffness-controlled techniques whenever large deformation from composite laminates is expected. The analytical techniques for stress analysis of composite tubes are reviewed, and the cumbersomeness of the method is highlighted. Finally, a simplified technique is presented to analyze composite tubes as a sandwich panel model. The results of the analysis are compared with the ANSYS and experimental results. Agreement between three methods is demonstrated. Moreover, guidelines for the design of composite tubes that exhibit large deformation before failure are presented.

  6. Polymer brushes

    SciTech Connect

    Milner, S.T. (Exxon Research and Engineering Co., Annandale, NJ (United States))

    1991-02-22

    Polymers attached by one end to an interface at relatively high coverage stretch away from the interface to avoid overlapping, forming a polymer brush. This simple picture may serve as the basis for models in diverse interfacial systems in polymer science, such as polymeric surfactants, stabilized suspensions of colloidal particles, and structures formed by block copolymers. The structure and dynamics of polymer brushes have been the subject of considerable theoretical and experimental activity in recent years. An account is given of recent advances in theoretical understanding of stretched polymers at interfaces, and the diverse experimental probes of systems modeled by brushes are briefly reviewed.

  7. Transparent Large Strain Thermoplastic Polyurethane Magneto-Active Nanocomposites

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  8. The Mechanical and Physical Properties of Thermoplastic Natural Rubber Hybrid Composites Reinforced with Hibiscus cannabinus, L and Short Glass Fiber

    Microsoft Academic Search

    W. N. Wan Busu; H. Anuar; S. H. Ahmad; R. Rasid; N. A. Jamal

    2010-01-01

    Thermoplastic natural rubber hybrid composites reinforced with kenaf and short glass fibers were compounded by melt blending method using an internal mixer, Thermo Haake 600P. Thermoplastic natural rubbers (TPNR) were prepared from polypropylene (PP), natural rubber (NR) and liquid natural rubber (TPNR) with ratio 70:20:10, which were blended using internal mixer for 12 minutes at 180°C and rotor speed 40 r.p.m.

  9. Prediction of the Elastic—Plastic Stress\\/Strain Response for Injection-Molded Long-Fiber Thermoplastics

    Microsoft Academic Search

    BA Nghiep Nguyen; Satish K. Bapanapalli; Vlastimil Kunc; Jay H. Phelps; Charles L. Tucker

    2009-01-01

    This article proposes a model to predict the elastic—plastic response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic—plastic behavior obeying the Ramberg—Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber orientation

  10. Functionalized Materials From Elastomers to High Performance Thermoplastics

    SciTech Connect

    Laura Ann Salazar

    2003-05-31

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

  11. The influence of mechanical properties in the electrical breakdown in poly-styrene-ethylene-butadiene-styrene thermoplastic elastomer

    NASA Astrophysics Data System (ADS)

    Kollosche, Matthias; Melzer, Michael; Becker, Andre; Stoyanov, Hristian; McCarthy, Denis N.; Ragusch, Hülya; Kofod, Guggi

    2009-03-01

    Dielectric elastomer actuators (DEA) are a class of eletro-active polymers with promising properties for a number of applications, however, such actuators are prone to failure. One of the leading failure mechanisms is the electrical breakdown. It is already well-known that the electro-mechanical actuation properties of DEA are strongly influenced by the mechanical properties of the elastomer and compliant electrodes. It was recently suggested that also the electrical breakdown in such soft materials is influenced by the mechanical properties of the elastomer. Here, we present stress-strain measurements obtained on two tri-block thermoplastic elastomers (SEBS 500040 and SEBS 500120, poly-styrene-ethylene-butadiene-styrene), with resulting large differences in mechanical properties, and compare them to measurements on the commonly used VHB 4910. Materials were prepared by either direct heat-pressing of the raw material, or by dissolving in toluene, centrifuging and drop-casting. Experiments showed that materials prepared with identical processing steps showed a difference in stiffness of about 20%, where centrifuged and drop-casted films were seen to be softer than heat-pressed films. Electric breakdown measurements showed that for identically processed materials, the stiffness seemed to be a strong indicator of the electrical breakdown strength. It was therefore found that processing leads to differences in both stiffness and electrical breakdown strength. However, unexpectedly, the softer drop-cast films had a much higher breakdown strength than the heatpressed films. We attribute this effect to impurities still present in the heat-pressed films, since these were not purified by centrifuging.

  12. Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

    NASA Astrophysics Data System (ADS)

    Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

    2015-05-01

    Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey's equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29th International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160?, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.

  13. Injection molded polymer optics in the 21st Century

    NASA Astrophysics Data System (ADS)

    Beich, William S.

    2005-08-01

    Precision polymer optics, manufactured by injection molding techniques, has been a key enabling technology for several decades now. The technology, which can be thought of as a subset of the wider field of precision optics manufacturing, was pioneered in the United States by companies such as Eastman Kodak, US Precision Lens, and Polaroid. In addition to suppliers in the U.S. there are several companies worldwide that design and manufacture precision polymer optics, for example Philips High Tech Plastics in Europe and Fujinon in Japan. Designers who are considering using polymer optics need a fundamental understanding of exactly how the optics are created. This paper will survey the technology and processes that are employed in the successful implementation of a polymer optic solution from a manufacturer's perspective. Special emphasis will be paid to the unique relationship between the molds and the optics that they produce. We will discuss the key elements of production: molding resins, molds and molding equipment, and metrology. Finally we will offer a case study to illustrate just how the optics designer carries a design concept through to production. The underlying theme throughout the discussion of polymer optics is the need for the design team to work closely with an experienced polymer optics manufacturer with a solid track record of success in molded optics. As will be seen shortly, the complex interaction between thermoplastics, molds, and molding machines dictates the need for working closely with a supplier who has the critical knowledge needed to manage all aspects of the program.

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

    NASA Astrophysics Data System (ADS)

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

    2005-06-01

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

  15. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

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

  16. Dynamics and thermodynamics of polymer glasses.

    PubMed

    Cangialosi, D

    2014-04-16

    The fate of matter when decreasing the temperature at constant pressure is that of passing from gas to liquid and, subsequently, from liquid to crystal. However, a class of materials can exist in an amorphous phase below the melting temperature. On cooling such materials, a glass is formed; that is, a material with the rigidity of a solid but exhibiting no long-range order. The study of the thermodynamics and dynamics of glass-forming systems is the subject of continuous research. Within the wide variety of glass formers, an important sub-class is represented by glass forming polymers. The presence of chain connectivity and, in some cases, conformational disorder are unfavourable factors from the point of view of crystallization. Furthermore, many of them, such as amorphous thermoplastics, thermosets and rubbers, are widely employed in many applications. In this review, the peculiarities of the thermodynamics and dynamics of glass-forming polymers are discussed, with particular emphasis on those topics currently the subject of debate. In particular, the following aspects will be reviewed in the present work: (i) the connection between the pronounced slowing down of glassy dynamics on cooling towards the glass transition temperature (Tg) and the thermodynamics; and, (ii) the fate of the dynamics and thermodynamics below Tg. Both aspects are reviewed in light of the possible presence of a singularity at a finite temperature with diverging relaxation time and zero configurational entropy. In this context, the specificity of glass-forming polymers is emphasized. PMID:24675099

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

    NASA Astrophysics Data System (ADS)

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

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

  18. Characterizing the strain rate sensitivity of the tensile mechanical properties of a thermoplastic composite

    NASA Astrophysics Data System (ADS)

    Brown, Kevin A.; Brooks, Richard; Warrior, Nicholas A.

    2009-01-01

    Thermoplastic composites (TPCs) are being given increased consideration for application in vehicle front-end structural crash components. However, studies on the high strainrate behavior of TPCs have been relatively limited. In this study, the effect of strain rate on the tensile properties of a woven fabric commingled E-glass/polypropylene thermoplastic composite was investigated over a strain-rate range of 10-4 to 70 s-1. Quasi-static tests were conducted in an electromechanical universal test machine. A specially designed test rig in conjunction with a falling weight drop tower was used for high strain-rate characterization. The experimental results show that the elastic modulus, ultimate strength, and strain to failure increase with increasing strain rate.

  19. Characterization of elastic-plastic and viscoplastic behavior of AS4/PEEK thermoplastic composite

    SciTech Connect

    Yoon, Kwangjoon.

    1990-01-01

    The elastic-plastic and strength properties of AS4/PEEK (APC-2) thermoplastic composite were characterized with respect to temperature variation by using a one parameter plasticity model and the elastic-viscoplastic properties were characterized by using a one parameter overstress viscoplasticity model and a modified Bodner and Patom's viscoplasticity model. These plasticity and viscoplasticity models were verified further for the case of unidirectional composite panels with cutouts and in laminates with and without hole.

  20. LDPE-based thermoplastic elastomers containing ground tire rubber with and without dynamic curing

    Microsoft Academic Search

    C. Radhesh Kumar; I Fuhrmann; J Karger-Kocsis

    2002-01-01

    Attempts were made to use a ground tire rubber (GTR) fraction (particle size: 0.4–0.7 mm) to produce thermoplastic elastomers (TPEs) composed of low-density polyethylene (LDPE), fresh rubber and GTR with and without dynamic curing. GTR has been thermomechanically decomposed in the presence (GTRPM) and absence of processing oil (GTRM) and its decomposition was followed by the increase in the acetone-soluble

  1. Ultrasonic evaluation of anisotropic damage in multiaxially textile-reinforced thermoplastic composites made from hybrid yarns

    Microsoft Academic Search

    W. Hufenbach; R. Böhm; A. Langkamp; L. Kroll; T. Ritschel

    2006-01-01

    The basic damage and failure models of multiaxially reinforced composites with a thermoplastic matrix are presented and verified.\\u000a Within the framework of continuum damage mechanics, a phenomenological model is introduced, where the damage is defined as\\u000a a change in the elasticity tensor. For damage identification, a specific ultrasonic device was developed. A combination of\\u000a an immersion set-up and a contact

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

    Microsoft Academic Search

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

    2012-01-01

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

  3. Rheology/Morphology Relationship of Immiscible EPDM/PP Based Thermoplastic Elastomer Blends

    NASA Astrophysics Data System (ADS)

    Shahbikian, S.; Carreau, P. J.; Heuzey, M. C.; Ellul, M. D.; Nadella, H. P.; Cheng, J.; Shirodkar, P.

    2008-07-01

    The rheological and morphological properties of non-plasticized/plasticized EPDM/PP based thermoplastic elastomers (TPEs) have been investigated. The addition of a plasticizer reduced the rheological properties of both components and their blends and increased their deformability. Complex morphological features (e.g., specific interfacial area and its orientation) of these blends have been analyzed after multiple start-up experiments using atomic force microscopy.

  4. Enhancement of physical properties of thermoplastic polyether-ester elastomer by reactive extrusion with chain extender

    Microsoft Academic Search

    Tae-young Lee; Chol-han Lee; Sunghwan Cho; Dong-ho Lee; Keun-Byoung Yoon

    2011-01-01

    The branched thermoplastic polyether-ester elastomer (TPEE) and diisocyanate compound was melt extruded in an effort to enhance\\u000a melt viscosity for the blow moulding process. The chain-extended TPEE was prepared with melt condensation of a branched TPEE\\u000a and 4,4?-diphenylmethane diisocyanate (MDI) for enhancement of the molecular weight of TPEE. The effects of MDI contents as\\u000a a chain extender on melt, thermal,

  5. New thermoplastic composite preforms based on split-film warp-knitting

    Microsoft Academic Search

    H Stumpf; E Mäder; S Baeten; T Pisanikovski; W Zäh; K Eng; C.-H Andersson; I Verpoest; K Schulte

    1998-01-01

    A newly developed type of dry thermoplastic textile preform incorporating non-crimp glass fibre reinforcements and matrix material in the form of split-film is presented. Weft-inserted warp knitting has been chosen as a textile production technique for its low cost. A specialized glass fibre\\/polypropylene matrix system has been proven to perform favourably in melt impregnation and to provide good composite properties.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  7. Miscibility and shape memory property of poly(vinyl chloride)\\/thermoplastic polyurethane blends

    Microsoft Academic Search

    Han Mo Jeong; Ji Hun Song; Sang Yoon Lee; Byung Kyu Kim

    2001-01-01

    The miscibility and the shape memory effect of PVC blends with segmented thermoplastic polyurethanes (TPUs), synthesized from diol-terminated polycaprolactone (PCL), hexamethylene diisocyanate, 4,4'-dihydroxy biphenyl, were studied. PVC was miscible with PCL segment in TPU and the glass transition temperature of this miscible amorphous domain varied smoothly with composition. When PVC was blended with TPU by the weight ratio of 8\\/2,

  8. Ultrasonic Attenuation Results of Thermoplastic Resin Composites Undergoing Thermal and Fatigue Loading

    NASA Technical Reports Server (NTRS)

    Madaras, Eric I.

    1998-01-01

    As part of an effort to obtain the required information about new composites for aviation use, materials and NDE researchers at NASA are jointly performing mechanical and NDE measurements on new composite materials. The materials testing laboratory at NASA is equipped with environmental chambers mounted on load frames that can expose composite materials to thermal and loading cycles representative of flight protocols. Applying both temperature and load simultaneously will help to highlight temperature and load interactions during the aging of these composite materials. This report highlights our initial ultrasonic attenuation results from thermoplastic composite samples that have undergone over 4000 flight cycles to date. Ultrasonic attenuation measurements are a standard method used to assess the effects of material degradation. Recently, researchers have shown that they could obtain adequate contrast in the evaluation of thermal degradation in thermoplastic composites by using frequencies of ultrasound on the order of 24 MHz. In this study, we address the relationship of attenuation measured at lower frequencies in thermoplastic composites undergoing both thermal and mechanical loading. We also compare these thermoplastic results with some data from thermoset composites undergoing similar protocols. The composite s attenuation is reported as the slope of attenuation with respect to frequency, defined as b = Da(f)/Df. The slope of attenuation is an attractive parameter since it is quantitative, yet does not require interface corrections like conventional quantitative attenuation measurements. This latter feature is a consequence of the assumption that interface correction terms are frequency independent. Uncertainty in those correction terms can compromise the value of conventional quantitative attenuation data. Furthermore, the slope of the attenuation more directly utilizes the bandwidth information and in addition, the bandwidth can be adjusted in the post processing stage to compensate for the loss of dynamic range of the signal as the composites age.

  9. Studies on Ethylene Propylene Diene Rubber and Thermoplastic Polyurethane Blends: The Effect of Maleation

    Microsoft Academic Search

    R. Dhamodharan; Pralay Maiti; Ganga Radhakrishnan

    2008-01-01

    Blends of maleated ethylene propylene diene rubber (EPDM) and thermoplastic polyurethane (TPU) have been studied to understand the effect of the maleation level of EPDM on the compatibility and morphology of the blends. Blends with different maleation levels on EPDM (0.25, 0.50, and 0.75 wt%) were compared for mechanical, thermal, and other properties. The appearance of single Tg for 0.5% and

  10. The structure and properties of weld lines in injection molded thermoplastics

    E-print Network

    Manisali, Ali Ihsan

    1980-01-01

    SCIENCE May 1980 Major Subject: Mechanical Engineering THE STRUCTURE AND PROPERTZES OF WELD LINES IN INJECTION MOLDED THERMOPLASTICS A Thesis by ALI IHSAN MANISALI Approved as to style and content by: (Chairman of Committee) (H of Department... Hopkins, Depart- ment Head, Department of Mechanical Engineering, for the financial support he has provided and to Mr. Harry Whitmors, Associate Director of TEES, for providing the injection molding machine, on which all of this research was done. I...

  11. Phase separation time\\/temperature dependence of thermoplastics-modified thermosetting systems

    Microsoft Academic Search

    Xiujuan Zhang; Xiaosu Yi; Yuanze Xu

    2008-01-01

    The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper\\u000a critical solution temperature (UCST) or lower critical solution temperature (LCST) were studied with emphasis on the temperature\\u000a dependency of the phase separation time and its potential application in the cure time-temperature processing window. We found\\u000a that the phase separation time\\/temperature relationship follows the simple Arrhenius equation. The

  12. Orthotropic structural analysis of short fiber filled thermoplastics: Abaqus - Moldflow interface, Experimental validation

    Microsoft Academic Search

    Ashok K Kancharla; Harindranath Sharma K; Paul Nugent

    Fiber-filled injection-molded parts contain complex fiber orientation patterns depending on the flow kinetics and the molding parameters. This fiber orientation state affects material properties including elastic modulus and strength and part properties including shrinkage and warpage. This requires anisotropic\\/orthotropic structural analysis, as isotropic analysis for these fiber-filled thermoplastics would generally yield inaccurate results. In this work, we report a problem

  13. Effect of silane treatment parameters on the silane layer formation and bonding to thermoplastic urethane

    Microsoft Academic Search

    Maija Hoikkanen; Mari Honkanen; Minnamari Vippola; Toivo Lepistö; Jyrki Vuorinen

    2011-01-01

    Enhancing adhesion is of primary importance in preparation of insert injection molded plastic–metal hybrids. Here, the combination of coupling agent application parameters and steel oxide microstructure effects on the adhesion in thermoplastic urethane–stainless steel hybrids was studied. The stainless steel oxide structure was first modified by electrolytical polishing and subsequent oxidation treatment, then the steel was coated with N-(?-aminoethyl)-?-aminopropyltrimethoxysilane (?-AEAPS)

  14. Experimental determination of friction coefficients between thermoplastics and rapid tooled injection mold materials

    Microsoft Academic Search

    Mary E. Kinsella; Blaine Lilly; Benjamin E. Gardner; Nick J. Jacobs

    2005-01-01

    Purpose – To determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection molding process using rapid-tooled mold inserts. Design\\/methodology\\/approach – Static coefficients of friction were determined for semi-crystalline high-density polyethylene (HDPE) and amorphous high-impact polystyrene (HIPS) against two rapid tooling materials, sintered steel with bronze (LaserForm ST-100) and stereolithography

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

    Microsoft Academic Search

    Mohsen Masoomi; Ali Asghar Katbab; Hossein Nazockdast

    2006-01-01

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

  16. Electroluminescent polymers

    Microsoft Academic Search

    Leni Akcelrud

    2003-01-01

    Electroluminescent polymers are reviewed in terms of synthesis and relationships between structure and light emission properties.The main concepts, problems and ideas related to the subject as a whole and to each class of electroluminescence (EL) polymer, have been systematically addressed. The elements of device architecture were considered, such as electrode characteristics and transport layers. The main mechanisms for light emission

  17. Polymers Guide

    NSDL National Science Digital Library

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

  18. Field Verification of Structural Performance of Thermoplastic Pipe Under Deep Backfill Conditions

    NASA Astrophysics Data System (ADS)

    Sargand, S.

    2002-05-01

    This report provides information regarding the structural performance of thermoplastic pipes under relatively deep soil cover conditions. The eighteen (12 HDPE, 6 PVC) thermoplastic pipes, with diameter ranging from 30 to 60 in., were instrumented with sensors, embedded with granular backfill in shallow trenches, and subjected to 20-ft or 40-ft high soil fill for about 10 months. Their installation plans involved two types of backfill soil, three relative compactions, and varying bedding thickness to study the effects of these installation parameters on the pipe performance. Once the field performance of each test pipe was presented and discussed, comparative cross examinations of the entire field data were made to identify the effects of various installation parameters on the pipe deformations/deflections and soil pressure against pipe. A comprehensive set of soil testing was performed in the laboratory to characterize each of the three soil types that existed in the field. Results from the shear strength tests were analyzed further to obtain hyperbolic model parameter values for these soils. Three analytical methods (modified Iowa formula, elastic solutions, and finite element) were applied to evaluate their abilities to predict the field performance of the thermoplastic pipes under relatively deep soil cover. In their applications, material properties measured in the laboratory were utilized as much as possible.

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

    PubMed

    Bin Khaled, Walid; Sameoto, Dan

    2014-05-14

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

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

    PubMed

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

    2013-11-30

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

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

    SciTech Connect

    Gase, K.M.; Hudacek, L.L.; Pesevski, G.T. [Advanced Elastomer Systems, Akron, OH (United States)

    1998-12-31

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

  2. Smart polymers for implantable electronics

    NASA Astrophysics Data System (ADS)

    Ware, Taylor H.

    Neural interfaces have been heavily investigated due to their unique ability to tap into the communication system of the body. Substrates compatible with microelectronics processing are planar and 5-7 orders of magnitude stiffer than the tissue with which they interact. This work enables fabrication of devices by photolithography that are stiff enough to penetrate soft tissue, change in stiffness to more closely match the modulus of tissue after implantation and adopt shapes to conform to tissue. Several classes of physiologically-responsive, amorphous polymer networks with the onset of the glass transition above 37 °C are synthesized and thermomechanically characterized. These glassy networks exhibit an isothermal reduction in modulus due to plasticization in the presence of aqueous fluids. Modulus after plasticization can be tuned by the dry glass transition temperature, degree of plasticization and crosslink density. Acrylic shape memory polymer based intracortical probes, which can change in modulus from above 1 GPa to less than 1 MPa, are fabricated through a transfer process that shields the substrate from processing and enhances adhesion to the microelectronics. Substrates capable of withstanding the conditions of photolithography are fabricated "thiol-ene" and "thiol-epoxy" substrates. These materials provide processing windows that rival engineering thermoplastics, swell less than 6% in water, and exhibit a controllable reduction in modulus from above 1 GPa to between 5 and 150 MPa. Substrates, planar for processing, that subsequently recover 3D shapes are synthesized by the formation of post-gelation crosslinks either covalent or supramolecular in nature. Acrylics with varied supramolecular, based on ureidopyrimidone moieties, and covalent crosslink density demonstrate triple-shape memory behavior. Post-gelation covalent crosslinks are established to permanently fix 3D shapes in thiol-ene networks. Devices fabricated include intracortical and nerve cuff electrodes. Neuronal viability and device performance suggest these materials may be suitable for the design of chronically-viable neural interfaces.

  3. High performance addition-type thermoplastics (ATTs) - Evidence for the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated material and a bismaleimide

    NASA Technical Reports Server (NTRS)

    Pater, R. H.; Soucek, M. D.; Chang, A. C.; Partos, R. D.

    1991-01-01

    Recently, the concept and demonstration of a new versatile synthetic reaction for making a large number of high-performance addition-type thermoplastics (ATTs) were reported. The synthesis shows promise for providing polymers having an attractive combination of easy processability, good toughness, respectable high temperature mechanical performance, and excellent thermo-oxidative stability. The new chemistry involves the reaction of an acetylene-terminated material with a bismaleimide or benzoquinone. In order to clarify the reaction mechanism, model compound studies were undertaken in solutions as well as in the solid state. The reaction products were purified by flash chromatography and characterized by conventional analytical techniques including NMR, FT-IR, UV-visible, mass spectroscopy, and high pressure liquid chromatography. The results are presented of the model compound studies which strongly support the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated compound and a bismaleimide or benzoquinone.

  4. Characterization of PEEK and short-fiber PEEK thermoplastic composites

    SciTech Connect

    Motz, H.

    1987-01-01

    Various topics in the areas of processing, structure, and properties in PEEK and its short-fiber composites are treated. Crystallization at constant temperatures and under nonisothermal conditions was analyzed using time-temperature-transformation curves. Correlation between isothermal and continuous cooling curves allows the rate of cooling needed to manufacture a product with a specific microstructure to be determined. The crystallization range (time or temperature) can be predicted for various heat treatments. In large-dimensioned polymer parts, crystallization does not develop uniformly. A finite-difference approach predicts the temperature distributions within the part for a variety of conditions, so that processing conditions that cause the inhomogeneities can be avoided. Crystallization temperature is important with respect to spherulitic morphology. The lathlike crystallites of adjacent spherulites formed at medium temperatures interweave, whereas a noncrystalline layer separates spherulites formed at higher temperatures. Carbon fibers are more effective nucleating agents than glass fibers, though not all fibers show transcrystallinity. Generally, the fibers did not seem to accelerate the crystallization process. But, they improve the mechanical properties, strength and modulus, at the expense of toughness.

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

    PubMed

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

    2014-12-19

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

  6. Polymer Particles

    NASA Astrophysics Data System (ADS)

    Okubo, Masayoshi

    In this special volume on polymer particles, recent trends and developments in the synthesis of nano- to micron-sized polymer particles by radical polymerization (Emulsion, Miniemulsion, Microemulsion, and Dispersion Polymerizations) of vinyl monomers in environmentally friendly heterogeneous aqueous and supercritical carbon dioxide fluid media are reviewed by prominent worldwide researchers. In addition to the important challenges and possibilities with regards to design and preparation of functionalized polymer particles of controlled size, the topics described are of great current interest due to the increased awareness of environmental issues.

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  9. Solid particle erosion of polymers and composites

    NASA Astrophysics Data System (ADS)

    Friedrich, K.; Almajid, A. A.

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Detyothin, Sukeewan

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

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

    SciTech Connect

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

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

    PubMed Central

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

    2012-01-01

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

  14. The impulse resistance welding: A new technique for joining advanced thermoplastic composite parts

    SciTech Connect

    Arias, M.; Ziegmann, G.

    1996-12-31

    Welding is a joining technique suitable for thermoplastic composites. This paper presents the development of a new, fast joining technique, which is based on the common resistance welding process. Heat is introduced by using electrical power pulses into the heating area and therefore this technique was called the Impulse Resistance Welding (IRW). The new technique will be described and discussed and the application of this technique by joining ribs to the skin of an aerodynamic spoiler part is demonstrated. The potential of an automation of the Impulse resistance welding process will be shown. Carbon fibre /PEEK (APC-2/AS4) has been selected as the material both for the skin and the rib.

  15. Parametric wear tests for drilling in thermoplastic fiber composites/metal stacks 

    E-print Network

    Hriscu, Iosif

    1991-01-01

    tolerance 2. Delaminations 0. 20 by 0. 07 inch radially from the hole 3. No more than 25% of the hole periphery frayed 4. Chipping no more than 0. 01 inch All the studies mentioned were done on graphite fiber - epoxy matrix (ther- mosetting) composites.... The object of this research is stacks of materials containing a graphite fiber - thermoplastic composite. From personal contacts with LTV company (Daren Davis, 1989), we established the following hole quality criteria for the present study; 1. 0. 003 inch...

  16. Nonlinear analysis of AS4/PEEK thermoplastic composite laminate using a one parameter plasticity model

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    A one-parameter plasticity model was shown to adequately describe the orthotropic plastic deformation of AS4/PEEK (APC-2) unidirectional thermoplastic composite. This model was verified further for unidirectional and laminated composite panels with and without a hole. The nonlinear stress-strain relations were measured and compared with those predicted by the finite element analysis using the one-parameter elastic-plastic constitutive model. The results show that the one-parameter orthotropic plasticity model is suitable for the analysis of elastic-plastic deformation of AS4/PEEK composite laminates.

  17. Characterization of elastic-plastic behavior of AS4/PEEK thermoplastic composite for temperature variation

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  18. Macroscopic thermoplastic model applied to the high pressure torsion of metallic glasses

    SciTech Connect

    Hobor, Sandor; Revesz, Adam [Department of Materials Physics, Eoetvoes University, P.O. Box 32, Budapest H-1518 (Hungary); Kovacs, Zsolt [Department of Materials Physics, Eoetvoes University, P.O. Box 32, Budapest H-1518 (Hungary); School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Belfield, Dublin 4 (Ireland)

    2009-07-15

    Shear deformation generated temperature rise in metallic glasses is estimated in a macroscopic three-dimensional axial symmetric thermoplastic model. Numerical solution of heat-conduction equation provides the time evolution and spatial distribution of temperature for high pressure torsion in the present paper. We have shown that small sample thickness and/or high deformation rate enables the temperature to exceed the glass transition in the entire sample, yielding a transition of the deformation mode from inhomogeneous to homogeneous viscous flow. However, in other cases only a small temperature increase is predicted in line with literature data.

  19. Laser transmission welding of absorber-free thermoplastics using dynamic beam superposition

    NASA Astrophysics Data System (ADS)

    Mamuschkin, Viktor; Olowinsky, Alexander; van der Straeten, Kira; Engelmann, Christoph

    2015-03-01

    So far, the main approach to weld absorber-free thermoplastics is exploiting their intrinsic absorption by choosing a proper wavelength of the laser. In order to melt the joining partners spatially restricted at the interface usually optics with a high numerical aperture are used. However, practice shows that the heat affected zone (HAZ) extends over a large area along the beam axis regardless of the optics used. Without clamping or convective cooling thermally induced expansion of the material can cause blowholes or deformation of the irradiated surface. To reduce the thermal stress on the part surface a dynamic beam superposition is investigated with the laser beam performing a precession movement.

  20. Loading rate effect on interlaminar fracture toughness of a thermoplastic composite

    NASA Technical Reports Server (NTRS)

    Mall, S.; Law, G. E.; Katouzian, M.

    1986-01-01

    A study was undertaken to investigate the loading rate effect on delamination fracture initiation toughness of a thermoplastic composite. For this purpose, double cantilever beam specimens of graphite/PEEK were tested in a displacement controlled mode using an Instron tensile test machine. Specimens were loaded at various crosshead speeds ranging from 0.05 cm/min to 100 cm/min. The interlaminar fracture toughness was found to decrease with increasing loading rate, and this decrease was more than one hundred percent over the five decades of loading rate employed.

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

    PubMed

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

    2014-11-19

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

  2. Antimicrobial Polymer

    DOEpatents

    McDonald, William F. (Utica, OH); Wright, Stacy C. (Flint, MI); Taylor, Andrew C. (Ann Arbor, MI)

    2004-09-28

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The polymeric composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from metals, metal alloys, metal salts, metal complexes and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one example embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl; and the metallic antimicrobial agent is selected from chelated silver ions, silver metal, chelated copper ions, copper metal, chelated zinc ions, zinc metal and mixtures thereof.

  3. Antimocrobial Polymer

    DOEpatents

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

    2005-09-06

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

  4. Glue Polymer

    NSDL National Science Digital Library

    Mid-continent Research for Education and Learning (McREL)

    2004-01-01

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

  5. Effect of Particle Size and Concentration of Flyash on Properties of Polyester Thermoplastic Elastomer Composites

    Microsoft Academic Search

    M. S. Sreekanth; V. A. Bambole; S. T. Mhaske; P. A. Mahanwar

    The performance of filled polymers is generally determined on the basis of the interface attraction of filler and polymers. Particulate filled polymer composites are becoming attractive because of their wide applications and low cost. In this study the effects of flyash with three varying particle size and filler concentrations (viz. 5 to 40 weight %) on the mechanical, thermal, electrical,

  6. High throughput multilayer microfluidic particle separation platform using embedded thermoplastic-based micropumping.

    PubMed

    Didar, Tohid Fatanat; Li, Kebin; Tabrizian, Maryam; Veres, Teodor

    2013-07-01

    We present an integrated thermoplastic elastomer (TPE) based multilayer microfluidic device with an embedded peristaltic micropump and through-holes membrane for high throughput particle sorting and separation. Fluidic and pneumatic layers of the device were fabricated using hot-embossing lithography and commercially available polycarbonate membranes were succcessfully sandwiched between two thermoplastic elastomer fluidic layers integrated to a peristaltic micropumping layer. The integrated peristaltic micropump induces turbulence at the top-microfluidic layer ring which successfully avoids particle aggregation and membrane blocking even at nanorange size. We present herein the general design of the device structure and pumping characteristics for three devices with membrane pore sizes of 10 ?m, 5 ?m and 800 nm. By using this design we have successfully demonstrated a separation efficiency as high as 99% of polystyrene microbeads with different sizes and most importantly the separation of 390 nm particles from 2 ?m beads was achieved. Using this device, we were also able to separate red blood cells with size of about 6-8 ?m from osteoblasts typically larger than 10 ?m to demonstrate the potential applicability of this platform for biological samples. The produced microfluidic chip operating at flow rates up to 100 ?l min(-1) allows us to achieve efficient high-throughput sorting and separation of target particles/cells. PMID:23640083

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

    PubMed Central

    Kaltenboeck, Georg; Harris, Thomas; Sun, Kerry; Tran, Thomas; Chang, Gregory; Schramm, Joseph P.; Demetriou, Marios D.; Johnson, William L.

    2014-01-01

    The ability of the rapid-capacitive discharge approach to access optimal viscosity ranges in metallic glasses for thermoplastic processing is explored. Using high-speed thermal imaging, the heating uniformity and stability against crystallization of Zr35Ti30Cu7.5Be27.5 metallic glass heated deeply into the supercooled region is investigated. The method enables homogeneous volumetric heating of bulk samples throughout the entire supercooled liquid region at high rates (~105?K/s) sufficient to bypass crystallization throughout. The crystallization onsets at temperatures in the vicinity of the “crystallization nose” were identified and a Time-Temperature-Transformation diagram is constructed, revealing a “critical heating rate” for the metallic glass of ~1000?K/s. Thermoplastic process windows in the optimal viscosity range of 100–104?Pa·s are identified, being confined between the glass relaxation and the eutectic crystallization transition. Within this process window, near-net forging of a fine precision metallic glass part is demonstrated. PMID:25269892

  8. Rheological properties and tunable thermoplasticity of phenolic rich fraction of pyrolysis bio-oil.

    PubMed

    Sahaf, Amir; Laborie, Marie-Pierre G; Englund, Karl; Garcia-Perez, Manuel; McDonald, Armando G

    2013-04-01

    In this work we report on the preparation, characterization, and properties of a thermally treated lignin-derived, phenolic-rich fraction (PRF) of wood pyrolysis bio-oil obtained by ethyl acetate extraction. The PRF was characterized for viscoelastic and rheological behavior using dynamic mechanical analysis (DMA) and cone and plate rheology. A unique thermoplastic behavior was evidenced. Heat-treated PRFs acquire high modulus but show low temperatures of thermal flow which can be systematically manipulated through the thermal pretreatment. Loss of volatiles, changes in molecular weight, and glass transition temperature (Tg) were investigated using thermogravimetric analysis (TGA), mass spectrometry (MS), and differential scanning calorimetry (DSC), respectively. Underlying mechanisms for the thermal and rheological behavior are discussed with regard to interactions between pyrolytic lignin nanoparticles present in the system and the role of volatile materials on determining the properties of the material resembling in several aspects to colloidal suspension systems. Low thermal flow temperatures and reversible thermal effects can be attributed to association of pyrolytic lignin particles due to intermolecular interactions that are easily ruptured at higher temperatures. The thermoplastic behavior of PRF and its low Tg is of particular interest, as it gives opportunities for application of this fraction in several melt processing and adhesive technologies. PMID:23424996

  9. An Elastic-Plastic Damage Model for Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil

    2009-08-11

    This article proposes an elastic-plastic damage model that combines micromechanical modeling with continuum damage mechanics to predict the stress-strain response of injection-molded long-fiber thermoplastics. The model accounts for distributions of orientation and length of elastic fibers embedded in a thermoplastic matrix whose behavior is elastic-plastic and damageable. The elastic-plastic damage behavior of the matrix is described by the modified Ramberg-Osgood relation and the three-dimensional damage model in deformation assuming isotropic hardening. Fiber/matrix debonding is accounted for using a parameter that governs the fiber/matrix interface compliance. A linear relationship between this parameter and the matrix damage variable is assumed. First, the elastic-plastic damage behavior of the reference aligned-fiber composite containing the same fiber volume fraction and length distribution as the actual composite is computed using an incremental Eshelby-Mori-Tanaka mean field approach. The incremental response of the latter is then obtained from the solution for the aligned-fiber composite by averaging over all fiber orientations. The model is validated against the experimental stress-strain results obtained for long-glass-fiber/polypropylene specimens.

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

    SciTech Connect

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

    2008-09-01

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

  11. Effects of HyperCoal addition on coke strength and thermoplasticity of coal blends

    SciTech Connect

    Toshimasa Takanohashi; Takahiro Shishido; Ikuo Saito [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan). Energy Technology Research Institute

    2008-05-15

    Ashless coal, also known as HyperCoal (HPC), was produced by thermal extraction of three coals of different ranks (Gregory caking coal, Warkworth steam coal, and Pasir subbituminous coal) with 1-methylnaphthalene (1-MN) at 360, 380, and 400{sup o}C. The effects of blending these HPCs into standard coal blends were investigated. Blending HPCs as 5-10% of a standard blend (Kouryusho:Goonyella:K9) enhanced the thermoplasticity over a wide temperature range. For blends made with the Pasir-HPC, produced from a noncaking coal, increasing the extraction temperature from 360 to 400{sup o}C increased the thermoplasticity significantly. Blends containing Warkworth-HPC, produced from a slightly caking coal, had a higher tensile strength than the standard blend in semicoke strength tests. The addition of 10% Pasir-HPC, extracted at 400{sup o}C, increased the tensile strength of the semicokes to the same degree as those made with Gregory-HPC. Furthermore, all HPC blends had a higher tensile strength and smaller weight loss during carbonization. These results suggest that the HPC became integrated into the coke matrix, interacting strongly with the other raw coals. 14 refs., 11 figs., 1 tab.

  12. Method and apparatus for producing composites of materials exhibiting thermoplastic properties

    DOEpatents

    Garvey, Raymond E. (Knoxville, TN); Grostick, Edmund T. (Faragut, TN)

    1992-01-01

    A mobile device for the complete consolidation of layers of material which exhibit thermoplastic properties for the formation of a composite of the layers upon a complex contoured substrate. The principal of the device is to provide heating into the molten temperature range of the thermoplastic material, applying sufficient pressure to the layers to cause flow of the plastic for a time sufficient to achieve full consolidation of the layers, and quickly cooling the structure to prevent delamination or other non-consolidation action. In the preferred form, there is an element to deposit a layer of the mateiral against another layer in close proximity. The two layers are pre-heated to near the melting temperature, and then further heated into the melting temperature range as they are brought into intimate contact with sufficient pressure to cause flow of the plastic for a time sufficient to achieve the full consolidation. The structure is then cooled. The mechanism for the application of pressure is selected such that the layers can be deformed to conform to a complex contour. In the preferred form, this pressurization is produced using a compliant hood that supplies both the pressure and at least a portion of the melting temperature, as well as the cooling. The apparatus, and method of operation, are described relative to the use of fiber-reinforced PEEK in the making of fully-consolidated composites. Other applications are discussed.

  13. Preparation and characterization of thermoplastic starches and their blends with poly(lactic acid).

    PubMed

    Yang, Yong; Tang, Zhaobin; Xiong, Zhu; Zhu, Jin

    2015-06-01

    Two different thermoplastic starches (TPS), namely maleic anhydride grafted starch (MA-g-starch) and epoxidized cardanol grafted starch (Epicard-g-starch), were successfully prepared by chemical modification without the addition of any plasticizer. The structure and properties were characterized by nuclear magnetic resonance (NMR), X-ray diffraction (XRD), hot press testing, scanning electron microscopy (SEM) and contact angle meter, respectively. Results from XRD showed that the highly crystalline structure of native starch was destroyed after modification. Continuous phase was obtained from both of the chemically modified starches after hot pressing at 130°C, indicating that they have good thermoplasticity. Subsequently, they were melt-blended with PLA. It was found that the Epicard-g-starch had a much finer dispersed phase size than MA-g-starch in PLA matrix due to its better hydrophobicity. As a result, the mechanical properties of PLA/Epicard-g-starch blend were superior to those of PLA/MA-g-starch blend. PMID:25840151

  14. Field Evaluation of the Potential for Creep in Thermoplastic Encapsulant Materials: Preprint

    SciTech Connect

    Kempe, M. D.; Miller, D. C.; Wohlgemuth, J.; Kurtz, S. R.; Moseley, J. M.; Shah, Q.; Tamizhmani, G.; Sakurai, K.; Inoue, M.; Doi, T.; Masuda, A.; Samuels, S. L.; Vanderpan, C. E.

    2012-06-01

    There has been recent interest in the use of thermoplastic encapsulant materials in photovoltaic modules to replace chemically crosslinked materials, e.g., ethylene-vinyl acetate. The related motivations include the desire to: reduce lamination time or temperature; use less moisture-permeable materials; use materials with better corrosion characteristics or with improved electrical resistance. However, the use of any thermoplastic material in a high-temperature environment raises safety and performance concerns, as the standardized tests currently do not expose the modules to temperatures in excess of 85 degrees C, though fielded modules may experience temperatures above 100 degrees C. Here we constructed eight pairs of crystalline-silicon modules and eight pairs of glass/encapsulation/glass thin-film mock modules using different encapsulant materials of which only two were designed to chemically crosslink. One module set was exposed outdoors with insulation on the back side in Arizona in the summer, and an identical set was exposed in environmental chambers. High precision creep measurements (+/- 20 um) and performance measurements indicate that despite many of these polymeric materials being in the melt state during outdoor deployment, very little creep was seen because of their high viscosity, temperature heterogeneity across the modules, and the formation of chemical crosslinks in many of the encapsulants as they aged. In the case of the crystalline silicon modules, the physical restraint of the backsheet reduced the creep further.

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

    NASA Astrophysics Data System (ADS)

    Patermann, Simone; Altstädt, Volker

    2015-05-01

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

  16. A Complex Shaped Reinforced Thermoplastic Composite Part Made of Commingled Yarns With Integrated Sensor

    NASA Astrophysics Data System (ADS)

    Risicato, Jean-Vincent; Kelly, Fern; Soulat, Damien; Legrand, Xavier; Trümper, Wolfgang; Cochrane, Cedric; Koncar, Vladan

    2015-02-01

    This paper focuses on the design and one shot manufacturing process of complex shaped composite parts based on the overbraiding of commingled yarns. The commingled yarns contain thermoplastic fibres used as the matrix and glass fibres as the reinforcement material. This technology reduces the flow path length for the melted thermoplastic and aims to improve the impregnation of materials with high viscosity. The tensile strength behaviour of the material was firstly investigated in order to evaluate the influence of the manufacturing parameters on flat structured braids that have been consolidated on a heating press. A good compatibility between the required geometry and the braiding process was observed. Additionally, piezo-resistive sensor yarns, based on glass yarns coated with PEDOT: PSS, have been successfully integrated within the composite structure. The sensor yarns have been inserted into the braided fabric, before consolidation. The inserted sensors provide the ability to monitor the structural health of the composite part in a real time. The design and manufacture of the complete complex shaped part has then been successfully achieved.

  17. Polymer solutions

    DOEpatents

    Krawczyk, Gerhard Erich (Bremen, DE); Miller, Kevin Michael (West Dundee, IL)

    2011-07-26

    There is provided a method of making a polymer solution comprising polymerizing one or more monomer in a solvent, wherein said monomer comprises one or more ethylenically unsaturated monomer that is a multi-functional Michael donor, and wherein said solvent comprises 40% or more by weight, based on the weight of said solvent, one or more multi-functional Michael donor.

  18. Polymers Pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore

    E-print Network

    Podgornik, Rudolf

    Polymers Pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore R. Podgornik, 1000 Ljubljana, Slovenia Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003, United States ABSTRACT: We investigate polymer partitioning from polymer

  19. Properties and recyclability of thermoplastic elastomer prepared from natural rubber powder (NRP) and high density polyethylene (HDPE)

    Microsoft Academic Search

    Pongdhorn Sae-Oui; Chakrit Sirisinha; Promsak Sa-nguanthammarong; Puchong Thaptong

    2010-01-01

    Preparation of thermoplastic natural rubber (TPNR) was carried out by blending high density polyethylene (HDPE) with natural rubber powder (NRP) obtained from spray drying of pre-vulcanized natural rubber latex. The blend ratio of NRP\\/HDPE was varied and the properties and recyclability of the TPNRs were investigated. The results reveal that, due to flow restriction of the crosslinked NRP, viscosity of

  20. Numerical Analysis of a High Power Piezoelectric Transducer Used in the Cutting and Welding of Thermoplastic Textiles

    Microsoft Academic Search

    João Batista da Silva; Nilson Noris Franceschetti; Julio Cezar Adamowski

    High power piezoelectric transducers have been used in the ultrasonic cutting and welding of thermoplastic textiles. The acoustical energy generated by a sandwich type power transducer is transferred to an wide blade-shaped horn through an acoustic amplifier. The transmission efficiency depends on the transducer and the horn assembly vibrational behavior. This paper presents a finite element analysis of a high

  1. Morphological and mechanical characterization of thermoplastic starch and its blends with polylactic acid using cassava starch and bagasse

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aims the use of an agro waste coming from the industrialization of cassava starch, known as cassava bagasse (BG). This material contains residual starch and cellulose fibers which can be used to obtain thermoplastic starch (TPS) and /or blends reinforced with fibers. In this context, it w...

  2. Thermal sonic analysis of polymer matrices and composites

    SciTech Connect

    Woo, E.M.; Seferis, J.C.

    1987-03-01

    A commercially available sonic Pulse Propagation Meter (PPM-5R) was utilized in this study to monitor kinetic changes of matrix polymers that may be encountered in processing operations of fiber-reinforced composites. Both thermoplastic polyetheretherketone (PEEK) and thermosetting epoxy resins and their carbon fiber composites were examined. During cure, the epoxy samples displayed obvious velocity changes at the initial softening and final cure transitions. For the neat PEEK samples, the sonic velocity decreased slowly as the temperature increased and the velocity dropped rapidly at a transition temperature of 160 C. Samples of carbon fiber-reinforced epoxy and PEEK composites were also investigated to examine the effect of fibers on the sonic velocity responses. The results show that the reinforcing fibers whose orientation coincides with the probe orientation have the most dampening effect on the detection of transitions using the sonic technique. Overall, the sonic technique for process monitoring is discussed in this paper. 20 references.

  3. Applications of polymer extrusion technology to coal processing

    NASA Technical Reports Server (NTRS)

    Lewis, D. W.

    1981-01-01

    Upon heating, many of the middle-aged bituminous coals exhibit a plasticity very similar to polyethylene for a few minutes. Plastic coal can be extruded, pelletized or molded using common plastics technology and equipment. Investigations concerning the plastic state of coals are conducted with the objective to develop techniques which will make useful commercial applications of this property possible. Experiments which show the characteristics of plastic-state coal are discussed, and problems related to a continuous extrusion of coal are considered. Probably the most significant difference between the continuous extrusion of coal and the extrusion of a thermoplastic polymer is that volatiles are continuously being released from the coal. Attention is given to aspects of dragflow, solids feeding, and melt pumping. Application potentials for plastic coal extrusion might be related to coal gasification, direct liquefaction, and coal combustion.

  4. Polymer additives

    SciTech Connect

    Carraher, C. [Florida Atlantic Univ., Boca Raton, FL (United States); Swift, G. [Rohm and Haas Co., Spring House, PA (United States)

    1993-12-31

    Polymers, because of the unique properties offered by them, are being employed to larger extents as additives. Polymeric additives may offer incentives such as cost, performance and unique properties. Polymeric additives have been used for years as viscosity modifiers in motor oils, plastisols, antifoaming agents and fillers. New uses are quickly emerging as permanent coloring agent, antibacterial agents and as delivery aids for metals and metal oxides.

  5. Conductive Polymers

    SciTech Connect

    Bohnert, G.W.

    2002-11-22

    Electroluminescent devices such as light-emitting diodes (LED) and high-energy density batteries. These new polymers offer cost savings, weight reduction, ease of processing, and inherent rugged design compared to conventional semiconductor materials. The photovoltaic industry has grown more than 30% during the past three years. Lightweight, flexible solar modules are being used by the U.S. Army and Marine Corps for field power units. LEDs historically used for indicator lights are now being investigated for general lighting to replace fluorescent and incandescent lights. These so-called solid-state lights are becoming more prevalent across the country since they produce efficient lighting with little heat generation. Conductive polymers are being sought for battery development as well. Considerable weight savings over conventional cathode materials used in secondary storage batteries make portable devices easier to carry and electric cars more efficient and nimble. Secondary battery sales represent an $8 billion industry annually. The purpose of the project was to synthesize and characterize conductive polymers. TRACE Photonics Inc. has researched critical issues which affect conductivity. Much of their work has focused on production of substituted poly(phenylenevinylene) compounds. These compounds exhibit greater solubility over the parent polyphenylenevinylene, making them easier to process. Alkoxy substituted groups evaluated during this study included: methoxy, propoxy, and heptyloxy. Synthesis routes for production of alkoxy-substituted poly phenylenevinylene were developed. Considerable emphasis was placed on final product yield and purity.

  6. Simulation and experimentation in melt spinning of liquid crystalline polymer reinforced composite fiber

    NASA Astrophysics Data System (ADS)

    He, Xiaojun

    Liquid crystalline polymers (LCPs) are a relatively new class of materials. These polymers usually consist of rigid rod-like molecular chains and they are capable of forming highly-oriented structures. Blending conventional thermoplastic polymers with LCPs produces fibrillar LCP structure that serve as the reinforcing component. The properties of the blends are affected by the size, shape and distribution of the LCPs in the matrix polymer, which in turn are related to the processing conditions which include the blend composition, the extrusion conditions and the viscosity ratio of the component polymers. We report the results of our study on the properties and morphology development of an in-situ composite based on the thermotropic liquid crystalline polymer (TLCP), Vectra. A mathematical model is also developed to simulate the deformation of TLCP during isothermal melt spinning. The simulation results are evaluated by comparing the model prediction of the rheological properties of the blend with those calculated from on-line measurement data. The model implication is also discussed in view of guiding the design of TLCP reinforcing composites.

  7. The role of nanoparticle synergies in modifying the thermal properties of biodegradable polymer blends

    NASA Astrophysics Data System (ADS)

    Yang, Kai; He, Shan; Davis, Rachel; Rafailovich, Miriam; Kashiwagi, Takashi

    2012-02-01

    Most of thermoplastic polymers are brittle, when sufficient amounts are added to get flame retardant properties.Furthermore, melt-blending starch with other biodegradable polymers is difficult since very few polymers are compatible with starches.We have developed a new nanoparticles where resorcinol diphenyl phosphates (RDP) is used to modify the surface energy, allowing the particles to be dispersed within polymer.When multiple types of particles share the same coating,they can be melt blended simultaneously and synergies can be achieved, imparting properties to the nanocomposite, which cannot be achieved by any single additive. Here we show that RDP modified starch, can be extruded together with the biodegradable polymers,Ecoflex and polylactic acid,to produce flame retardant nanocomposites which can pass the UL-94-V0 test.TEM images of the blend show that the RDP-coated starch particles were well dispersed within the polymer matrix providing the flame retardant properties,while the RDP clays are reducing the interfacial tension and contributing to compatibilization. Nanomechanical measurements of the chars remaining after cone calorimetric measurements indicate that maintaining flexibility of the chars may be an additional factor in achieving good flame retardant properties.

  8. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

  9. Recycling and processing of several typical crosslinked polymer scraps with enhanced mechanical properties based on solid-state mechanochemical milling

    NASA Astrophysics Data System (ADS)

    Lu, Canhui; Zhang, Xinxing; Zhang, Wei

    2015-05-01

    The partially devulcanization or de-crosslinking of ground tire rubber (GTR), post-vulcanized fluororubber scraps and crosslinked polyethylene from cable scraps through high-shear mechanochemical milling (HSMM) was conducted by a modified solid-state mechanochemical reactor. The results indicated that the HSMM treated crosslinked polymer scraps can be reprocessed as virgin rubbers or thermoplastics to produce materials with high performance. The foamed composites of low density polyethylene/GTR and the blend of post-vulcanized flurorubber (FKM) with polyacrylate rubber (ACM) with better processability and mechanical properties were obtained. The morphology observation showed that the dispersion and compatibility between de-crosslinked polymer scraps and matrix were enhanced. The results demonstrated that HSMM is a feasible alternative technology for recycling post-vulcanized or crosslinked polymer scraps.

  10. High-Performance Polymers Having Low Melt Viscosities

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.

    2005-01-01

    High-performance polymers that have improved processing characteristics, and a method of making them, have been invented. One of the improved characteristics is low (relative to corresponding prior polymers) melt viscosities at given temperatures. This characteristic makes it possible to utilize such processes as resin-transfer molding and resin-film infusion and to perform autoclave processing at lower temperatures and/or pressures. Another improved characteristic is larger processing windows that is, longer times at low viscosities. Other improved characteristics include increased solubility of uncured polymer precursors that contain reactive groups, greater densities of cross-links in cured polymers, improved mechanical properties of the cured polymers, and greater resistance of the cured polymers to chemical attack. The invention is particularly applicable to poly(arylene ether)s [PAEs] and polyimides [PIs] that are useful as adhesives, matrices of composite materials, moldings, films, and coatings. PAEs and PIs synthesized according to the invention comprise mixtures of branched, linear, and star-shaped molecules. The monomers of these polymers can be capped with either reactive end groups to obtain thermosets or nonreactive end groups to obtain thermoplastics. The synthesis of a polymeric mixture according to the invention involves the use of a small amount of a trifunctional monomer. In the case of a PAE, the trifunctional monomer is a trihydroxy- containing compound for example, 1,3,5-trihydroxybenzene (THB). In the case of a PI, the trifunctional monomer is a triamine for example, triamino pyrimidine or melamine. In addition to the aforementioned trifunctional monomer, one uses the difunctional monomers of the conventional formulation of the polymer in question (see figure). In cases of nonreactive end caps, the polymeric mixtures of the invention have melt viscosities and melting temperatures lower than those of the corresponding linear polymers of equal molecular weights. The lower melting temperatures and melt viscosities provide larger processing windows. In cases of reactive end caps, the polymeric mixtures of the invention have lower melt viscosities before curing and the higher cross-link densities after curing (where branching in the uncured systems would become cross-links in the cured systems), relative to the corresponding linear polymers of equal molecular weights. The greater cross-link densities afford increased resistance to chemical attack and improved mechanical properties.

  11. Polymer/clay/wood nanocomposites: The effect of incorporation of nanoclay into the wood/polymer composites

    NASA Astrophysics Data System (ADS)

    Hetzer, Max E.

    Thermoplastic composites play an important role in our society. The uses of these composites range from cookware to components for the space shuttle. In recent years, researchers at Toyota developed numerous methods of preparation for composites made from olefins and inorganic fillers such as clay and calcium carbonate. Wood fibers have been used as reinforcing filler in polymer matrices for the past several decades. The advantages of using wood fibers as reinforcing fillers are: the low cost of the fibers (or flour), low density, and resistance to breakage. The disadvantage of using wood as a filler is the thermal instability of wood above 200 °C. The majority of thermoplastics exhibit melting points between 160 and 220 °C, which is in the range of thermal decomposition of wood. Nanoclay was first successfully used as a filler in polyolefin materials by the Toyota research team in early 90s. It was found that the addition of a small amount (< 5 wt.%) of nanoclay increased the mechanical properties of a Nylon-6 matrix dramatically. Since Nylon-6 is a hydrophilic material no compatibilizer was necessary to exfoliate the nanoclay. The use of compatibilizers such as maleic modified polyethylenes (MAPEs) is necessary upon addition of nanoclay to a hydrophobic polyolefin systems such polyethylene (PE) or polypropylene (PP). Few researchers have attempted to reinforce the polymer matrix via the use of the nanoclay for use as a matrix in wood/polymer composites. High molecular weight and low molecular weight MAPEs have been used to enhance the bonding between the nanoclay and the polymer matrix as well as between the wood flour and the polymer matrix. The effects of combinations of the high and low molecular weight MAPEs on the mechanical and thermal properties of polymer/clay nanocomposites (PCNs) and of wood/polymer/clay composites (WPCs) were investigated. The effects of adding nanoclay to wood/polymer systems on the mechanical and thermal properties of the composites were also investigated. A model based on the Halpin-Tsai model was developed that predicts the (Young's) modulus-temperature relationship of the composites based on discontinuous fillers. It was found that the molecular weight of the compatibilizer significantly affects the exfoliation/dispersion of the nanoclay within the polymer matrix. A compatibilizer containing a high Mw fraction based on high density polyethylene (HDPE) and a low Mw fraction based on linear low density polyethylene (LLDPE) was found to be the most effective at enhancing the thermal and mechanical properties of PCNs and WPCs. A compatibilizer containing greater than 60 wt.% high Mw fraction resulted in a 30% increase of the modulus and a 15°C increase of the heat deflection temperature (HDT). The addition of the nanoclay had a detrimental effect on the moduli of PCNs and WPCs when a low Mw compatibilizer based on LLDPE was used. The moduli of these composites increased with increasing high Mw content of the compatibilizer and increasing nanoclay content. The addition of the nanoclay to wood/polymer composites resulted in an increased modulus of elasticity and HDT of these composites. The developed model quantitatively predicts the modulus-temperature relationship of the fiber containing composites. It was found that the modulus of the composites varies linearly with temperature and was highly dependent on the exfoliation of the nanoclay within the polymer matrix.

  12. Thermo-mechanical behaviors of thermoplastic starch derived from sugar palm tree (Arenga pinnata).

    PubMed

    Sahari, J; Sapuan, S M; Zainudin, E S; Maleque, M A

    2013-02-15

    In recent years, increasing environmental concerns focused greater attention on the development of biodegradable materials. A thermoplastic starch derived from bioresources, sugar palm tree was successfully developed in the presence of biodegradable glycerol as a plasticizer. Sugar palm starch (SPS) was added with 15-40 w/w% of glycerol to prepare workable bioplastics and coded as SPS/G15, SPS/G20, SPS/G30 and SPS/G40. The samples were characterized for thermal properties, mechanical properties and moisture absorption on exposure to humidity were evaluated. Morphological studies through scanning electron microscopy (SEM) were used to explain the observed mechanical properties. Generally, the addition of glycerol decrease the transition temperature of plasticized SPS. The mechanical properties of plasticized SPS increase with the increasing of glycerol but up to 30 w/w%. Meanwhile, the water absorption of plasticized SPS decrease with increasing of glycerol. PMID:23399210

  13. Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation

    NASA Astrophysics Data System (ADS)

    Giraud, Isabelle; Franceschi-Messant, Sophie; Perez, Emile; Lacabanne, Colette; Dantras, Eric

    2013-02-01

    In this work, different sizing agent aqueous dispersions based on polyetherimide (PEI) were elaborated in order to improve the interface between carbon fibers and a thermoplastic matrix (PEEK). The dispersions were obtained by the emulsion/solvent evaporation technique. To optimize the stability and the film formation on the fibers, two surfactants were tested at different concentrations, with different concentrations of PEI. The dispersions obtained were characterized by dynamic light scattering (DLS) and the stability evaluated by analytical centrifugation (LUMiFuge). The selected dispersions were tested for film formation ability by scanning electron microscopy (SEM), and the sizing performance was assessed by observation of the fiber/matrix interface by SEM. The results revealed that an aqueous dispersion of PEI, stabilized by sodium dodecyl sulfate as the surfactant, led to very stable sizing agent aqueous dispersion with ideal film formation and better interface adhesion.

  14. Isosorbide, a green plasticizer for thermoplastic starch that does not retrogradate.

    PubMed

    Battegazzore, Daniele; Bocchini, Sergio; Nicola, Gabriele; Martini, Eligio; Frache, Alberto

    2015-03-30

    Isosorbide is a non-toxic biodegradable diol derived from bio-based feedstock. It can be used for preparing thermoplastic starch through a semi-industrial process of extrusion. Isosorbide allows some technological advantages with respect to classical plasticizers: namely, direct mixing with starch, energy savings for the low processing temperature required and lower water uptake. Indeed, maize starch was directly mixed with the solid plasticizer and direct fed in the main hopper of a co-rotating twin screw extruder. Starch plasticization was assessed by X-ray diffraction (XRD) and dynamic-mechanical analysis (DMTA). Oxygen permeability, water uptake and mechanical properties were measured at different relative humidity (R.H.) values. These three properties turned out to be highly depending on the R.H. No retrogradation and changing of the material properties were occurred from XRD and DMTA after 9 months. PMID:25563947

  15. Bonding and nondestructive evaluation of graphite/PEEK composite and titanium adherends with thermoplastic adhesives

    NASA Technical Reports Server (NTRS)

    Hodges, W. T.; Tyeryar, J. R.; Berry, M.

    1985-01-01

    Bonded single overlap shear specimens were fabricated from Graphite/PEEK (Polyetheretherketone) composite adherends and titanium adherends. Six advanced thermoplastic adhesives were used for the bonding. The specimens were bonded by an electromagnetic induction technique producing high heating rates and high-strength bonds in a few minutes. This contrasts with conventionally heated presses or autoclaves that take hours to process comparable quality bonds. The Graphite/PEEK composites were highly resistant to delamination during the testing. This allowed the specimen to fail exclusively through the bondline, even at very high shear loads. Nondestructive evaluation of bonded specimens was performed ultrasonically by energizing the entire thickness of the material through the bondline and measuring acoustic impedance parameters. Destructive testing confirmed the unique ultrasonic profiles of strong and weak bonds, establishing a standard for predicting relative bond strength in subsequent specimens.

  16. Effects of vapor grown carbon nanofibers on electrical and mechanical properties of a thermoplastic elastomer

    NASA Astrophysics Data System (ADS)

    Basaldua, Daniel Thomas

    Carbon nanofiber (CNF) reinforced composites are exceptional materials that exhibit superior properties compared to conventional composites. This paper presents the development of a vapor grown carbon nanofiber (VGCNF) thermoplastic polyurethane (TPU) composite by a melt mixing process. Dispersion and distribution of CNFs inside the TPU matrix were examined through scanning electron microscopy to determine homogeneity. The composite material underwent durometer, thermal gravimetric analysis, differential scanning calorimetry, heat transfer, hysteresis, dynamic modulus, creep, tensile, abrasion, and electrical conductivity testing to characterize its properties and predict behavior. The motivation for this research is to develop an elastomer pad that is an electrically conductive alternative to the elastomer pads currently used in railroad service. The material had to be a completely homogenous electrically conductive CNF composite that could withstand a harsh dynamically loaded environment. The new material meets mechanical and conductive requirements for use as an elastomer pad in a rail suspension.

  17. From Process Modeling to Elastic Property Prediction for Long-Fiber Injection-Molded Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Frame, Barbara J.; Phelps, Jay; Tucker III, Charles L.; Bapanapalli, Satish K.; Holbery, James D.; Smith, Mark T.

    2007-09-13

    This paper presents an experimental-modeling approach to predict the elastic properties of long-fiber injection-molded thermoplastics (LFTs). The approach accounts for fiber length and orientation distributions in LFTs. LFT samples were injection-molded for the study, and fiber length and orientation distributions were measured at different locations for use in the computation of the composite properties. The current fiber orientation model was assessed to determine its capability to predict fiber orientation in LFTs. Predicted fiber orientations for the studied LFT samples were also used in the calculation of the elastic properties of these samples, and the predicted overall moduli were then compared with the experimental results. The elastic property prediction was based on the Eshelby-Mori-Tanaka method combined with the orientation averaging technique. The predictions reasonably agree with the experimental LFT data

  18. Injection-Molded Long-Fiber Thermoplastic Composites: From Process Modeling to Prediction of Mechanical Properties

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Jin, Xiaoshi; Tucker III, Charles L.; Costa, Franco

    2013-12-18

    This article illustrates the predictive capabilities for long-fiber thermoplastic (LFT) composites that first simulate the injection molding of LFT structures by Autodesk® Simulation Moldflow® Insight (ASMI) to accurately predict fiber orientation and length distributions in these structures. After validating fiber orientation and length predictions against the experimental data, the predicted results are used by ASMI to compute distributions of elastic properties in the molded structures. In addition, local stress-strain responses and damage accumulation under tensile loading are predicted by an elastic-plastic damage model of EMTA-NLA, a nonlinear analysis tool implemented in ABAQUS® via user-subroutines using an incremental Eshelby-Mori-Tanaka approach. Predicted stress-strain responses up to failure and damage accumulations are compared to the experimental results to validate the model.

  19. Thermal Behaviour of Nanocomposites based on Glycerol Plasticized Thermoplastic Starch and Cellulose Nanocrystallites

    NASA Astrophysics Data System (ADS)

    Kaushik, Anupama; Kaur, Ramanpreet

    2011-12-01

    The objective of this study was to study the thermal behaviour of cellulose nanocrystals/TPS based nanocomposites. Nanocrystalline cellulose was isolated from cotton linters using sonochemical method and characterized through WAXRD & TEM. These nanocrystals were then dispersed in glycerol plasticized starch in varying proportions and films were cast. The thermal degradation of thermoplastic starch/cellulose nanocrystallite nanocomposites was studied using TGA under nitrogen atmosphere. Thermal degradation was carried out for nanocomposites at a rate of 10 °C/min and at different rates under nitrogen atmosphere namely 2, 5, 10, 20 and 40 °C/min for nanocomposites containing 10% cellulose nanocrystals. Ozawa and Flynn and Kissinger methods were used to determine the apparent activation energy of these nanocomposites. The addition of cellulose nanocrystallites produced a significant effect on the activation energy for thermal degradation of the composites materials in comparison with the matrix alone. These nanocomposites are potential applicant for food packaging applications.

  20. Measurement of internal die pressure distributions during pultrusion of thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Fanucci, Jerome P.; Nolet, Stephen C.; Koppernaes, Christian; Kim, Young R.

    This paper describes the development and use of a thin, disposable pressure sensor designed specifically for monitoring pointwise through-the-thickness consolidation forces developed during composite processing. The unique postage stamp-sized sensor (11.1 mm diameter active gage area and 0.31 mm thickness) can be placed directly at points in or on a laminate where pressure data is desired. The sonsor's small dimensions and low cost permit it to be treated as a disposable item in aerospace and other composite fabrication applications. This paper will illustrate the use of the sensor as a means of measuring the pressures developed inside a die during the pultrusion of a graphite/ULTEM thermoplastic structure, as well as with other pultrusion processing examples.

  1. Development of a two-dimensional thermal model for the steady state thermoplastic pultrusion process

    NASA Astrophysics Data System (ADS)

    Ruan, Yimin; Liu, Joshua C.; Chesonis, D. C.; Carvell, Lee A.

    A two-dimensional steady state heat transfer model is developed in this report for the thermoplastic pultrusion process. In this model, the finite element method with a stream line diffusion approach is used. The stream line diffusion method will minimize the numerical oscillations when the pulling speed is high and the finite element mesh is coarse. The crystallization kinetics reported by Ozawa is employed to calculate the relative crystallinity and the heat released due to the crystallization process during cooling. It is assumed the taper angle of the consolidation die is small so that the pultrusion can be approximated as an orthotropic material. The volume fractions of void, matrix, and fiber are defined based on material densities and consolidation strains. Examples for pultrusion of APC-2 are studied using this finite element model.

  2. Modelling the spot shape influence on high-speed transmission lap welding of thermoplastics films

    NASA Astrophysics Data System (ADS)

    Coelho, João M. P.; Abreu, Manuel A.; Carvalho Rodrigues, F.

    2008-01-01

    Modelling high-speed laser lap welding of thermoplastic films has been accomplished and the influence of laser beam spot shape, dimensions, and position relative to sample displacement was analysed. Engineering parameters predicted by the model were applied to lap weld of high- and low-density polyethylene transparent samples with thickness between 10 and 100 ?m, and experimentally validated. Experimental set-up allowed reaching welding constant linear velocities up to 10 m/s. Theoretical and experimental data show coincidence. Weld strength increases for larger beam spot diameters, and elliptical beam spots increase weld efficiency, allowing higher processing speeds or decreasing required laser power. An angular deviation of elliptical beam spot with regard to the sample's movement direction causes an increase of weld strength and a decrease of welding speed.

  3. Effect of thermoplastic coating on interfacial adhesion of oxygen-plasma-pretreated PBO/PPESK composites

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyi; Chen, Ping; Han, Debin; Yu, Qi; Ding, Zhenfeng; Zhu, Xiuling

    2013-02-01

    To improve the interfacial adhesion of PBO/PPESK composite, thermoplastic resins were coated onto the fiber surface after plasma pretreatment. Two coating resins applied in this study were chemically linked with the plasma pretreated fibers, which was confirmed by X-ray photoelectron spectroscopy. The fiber surface morphologies and wettability were analyzed by scanning electron microscope (SEM) and dynamic contact angle analysis, respectively. The interfacial adhesion performance of the PBO fiber-reinforced PPESK composite was measured by interlaminar shear strength (ILSS) and water absorption tests. Fracture mechanisms of the composites were examined by SEM. The results indicated that after coating the surface wettability was improved and the ILSS had an increment of 80.8% for phenolphthalein poly (ether ketone) coating and 30.3% for phenolphthalein poly (ether sulfone) coating.

  4. Laser Surface Pre-treatment of Aluminium for Hybrid Joints with Glass Fibre Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Heckert, André; Zaeh, Michael F.

    Lightweight construction is a major trend in the automotive industry. Theconnection of fibre reinforced plastics with aluminium is consequently seen as promising prospect. In this regard, thermal joining can be applied for bonding of such hybrid joints. But in order to create a load bearing metal plastic joint, the surface of the metal has to be pre-treated. Recent research has shown that with laser surface pre-treatment high joint strengths are obtained. Yet there are a variety of laser sources and manufacturable surface topographies with structure sizes ranging from macroscopic to nanoscopic profiles. Within this work,macroscopic, microscopic and nanoscopic laser processed structures are created on aluminium and consequently joined to glass fibre reinforced thermoplastics of different fibre length and fibre content. High shear tensile strengths of up to 42 N/mm2 were obtained depending on the allocated material and the surface pre-treatment.

  5. In vitro retention of a new thermoplastic titratable mandibular advancement device.

    PubMed

    Braem, Marc

    2015-01-01

    Oral appliance (OA) therapy with a mandibular advancement device (OAm) is a non-invasive, alternative approach to maintaining upper airway patency. The main requirement for an OAm to be effective is the adequate retention on the teeth while the patient is asleep. We evaluated the retentive forces of a new low-cost, customizable, titratable, thermoplastic OAm (BluePro (®); BlueSom, France). Dental impressions and casts were made for one patient with complete upper and lower dental arches including the third molars and class II bite proportions. A setup based on Frasaco ANA-4 models was also used. Two protrusive positions of the mandible were investigated: 3 mm and 8 mm, representing respectively 25% and 65% of the maximal protrusion. The forces required to remove the BluePro (®) device from the carriers were recorded continuously over 730 cycles (=365 days, twice a day) to simulate 1 year of clinical use. At 8 mm protrusion the BluePro (®) device showed retentive forces of ~27N. There was a slight but non-significant decrease in retentive forces in the tests on the epoxified carriers which was not found on the ANA-4 carriers. There were no significant differences between the carriers as a function of protrusion. The BluePro (®) device tested in the present study possesses sufficient retention forces to resist initial jaw opening forces and full mouth opening forces estimated to be ~20N. It could therefore broaden the indications for use of thermoplastic OAms. It could provide a temporary OAm while a custom-made OAm is being manufactured or repaired. Patients could be provided with a low-cost try-out device capable of reliable titration, providing an indication of effectiveness and of patient acceptance of an OAm, although the effect of device shape and size on therapeutic outcome is not yet known. Finally it could provide an affordable OAm solution in resource-restricted healthcare settings. PMID:25901281

  6. Genome Regions Associated with Functional Performance of Soybean Stem Fibers in Polypropylene Thermoplastic Composites

    PubMed Central

    Reinprecht, Yarmilla; Arif, Muhammad; Simon, Leonardo C.; Pauls, K. Peter

    2015-01-01

    Plant fibers can be used to produce composite materials for automobile parts, thus reducing plastic used in their manufacture, overall vehicle weight and fuel consumption when they replace mineral fillers and glass fibers. Soybean stem residues are, potentially, significant sources of inexpensive, renewable and biodegradable natural fibers, but are not curretly used for biocomposite production due to the functional properties of their fibers in composites being unknown. The current study was initiated to investigate the effects of plant genotype on the performance characteristics of soybean stem fibers when incorporated into a polypropylene (PP) matrix using a selective phenotyping approach. Fibers from 50 lines of a recombinant inbred line population (169 RILs) grown in different environments were incorporated into PP at 20% (wt/wt) by extrusion. Test samples were injection molded and characterized for their mechanical properties. The performance of stem fibers in the composites was significantly affected by genotype and environment. Fibers from different genotypes had significantly different chemical compositions, thus composites prepared with these fibers displayed different physical properties. This study demonstrates that thermoplastic composites with soybean stem-derived fibers have mechanical properties that are equivalent or better than wheat straw fiber composites currently being used for manufacturing interior automotive parts. The addition of soybean stem residues improved flexural, tensile and impact properties of the composites. Furthermore, by linkage and in silico mapping we identified genomic regions to which quantitative trait loci (QTL) for compositional and functional properties of soybean stem fibers in thermoplastic composites, as well as genes for cell wall synthesis, were co-localized. These results may lead to the development of high value uses for soybean stem residue. PMID:26167917

  7. Mechanisms of shark skin suppression by novel polymer processing aids

    NASA Astrophysics Data System (ADS)

    Wagner, M. H.; Himmel, T.; Kulikov, O.; Hornung, K.

    2014-05-01

    The extrusion rate of polyethylene (PE) with narrow molar weight distribution, as e.g. metallocen catalysed polyethylene (m-PE), is limited by melt fracture. The first level of fracture is a surface defect called sharkskin. Common polymer processing aids based on fluorinated polymers shift the onset of sharkskin to higher extrusion rates by creating a "low energy surface" at the die wall and promoting wall slip. Alternatively, Kulikov et al. [1, 2] suggested thermoplastic elastomers (TPE) for sharkskin suppression, and Müller [3] showed the suitability of some TPEs as polymer processing aids. We investigated the slip velocity of several TPEs against steel, and the slip velocity in a polymeric interface between polyethylene (PE) and TPE by rotational plate-plate rheometry in the Newtonian flow regime. TPEs with lower viscosities showed higher slip velocities against steel. However, the interfacial slip velocities between PE and TPE were found to be viscosity independent. In both cases, the slip velocity was found to be proportional to the applied shear stress.

  8. Crash simulation of hybrid structures considering the stress and strain rate dependent material behavior of thermoplastic materials

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Schöngart, M.; Weber, M.; Klein, J.

    2015-05-01

    Thermoplastic materials are more and more used as a light weight replacement for metal, especially in the automotive industry. Since these materials do not provide the mechanical properties, which are required to manufacture supporting elements like an auto body or a cross bearer, plastics are combined with metals in so called hybrid structures. Normally, the plastics components are joined to the metal structures using different technologies like welding or screwing. Very often, the hybrid structures are made of flat metal parts, which are stiffened by a reinforcement structure made of thermoplastic materials. The loads on these structures are very often impulsive, for example in the crash situation of an automobile. Due to the large stiffness variation of metal and thermoplastic materials, complex states of stress and very high local strain rates occur in the contact zone under impact conditions. Since the mechanical behavior of thermoplastic materials is highly dependent on these types of load, the crash failure of metal plastic hybrid parts is very complex. The problem is that the normally used strain rate dependent elastic/plastic material models are not capable to simulate the mechanical behavior of thermoplastic materials depended on the state of stress. As part of a research project, a method to simulate the mechanical behavior of hybrid structures under impact conditions is developed at the IKV. For this purpose, a specimen for the measurement of mechanical properties dependet on the state of stress and a method for the strain rate depended characterization of thermoplastic materials were developed. In the second step impact testing is performed. A hybrid structure made from a metal sheet and a reinforcement structure of a Polybutylenterephthalat Polycarbonate blend is tested under impact conditions. The measured stress and strain rate depended material data are used to simulate the mechanical behavior of the hybrid structure under highly dynamic load with impact velocities up to 5 m/s. The mechanical behavior of the plastics structure is simulated using a quadratic yield surface, which takes the state of stress and the strain rate into account. The FE model is made from mid surface elements to reduce the computing time.

  9. Total Life Cycle-Based Materials Selection for Polymer Metal Hybrid Body-in-White Automotive Components

    Microsoft Academic Search

    M. Grujicic; V. Sellappan; T. He; Norbert Seyr; Andreas Obieglo; Marc Erdmann; Jochen Holzleitner

    2009-01-01

    Over the last dozen of years, polymer metal hybrid (PMH) technologies have established themselves as viable alternatives for\\u000a use in light-weight automotive body-in-white bolt-on as well as load-bearing (structural) components. Within the PMH technologies,\\u000a sheet-metal stamped\\/formed and thermoplastic injection molding subcomponents are integrated into a singular component\\/module.\\u000a Due to attending synergetic effects, the performance of the PMH component typically exceeds

  10. Characterization of passive polymer optical waveguides

    NASA Astrophysics Data System (ADS)

    Joehnck, Matthias; Kalveram, Stefan; Lehmacher, Stefan; Pompe, Guido; Rudolph, Stefan; Neyer, Andreas; Hofstraat, Johannes W.

    1999-05-01

    The characterization of monomode passive polymer optical devices fabricated according to the POPCORN technology by methods originated from electron, ion and optical spectroscopy is summarized. Impacts of observed waveguide perturbations on the optical characteristics of the waveguide are evaluated. In the POPCORN approach optical components for telecommunication applications are fabricated by photo-curing of liquid halogenated (meth)acrylates which have been applied on moulded thermoplastic substrates. For tuning of waveguide material refractive indices with respect to the substrate refractive index frequently comonomer mixtures are used. The polymerization characteristics, especially the polymerization kinetics of individual monomers, determine the formation of copolymers. Therefore the unsaturation as function of UV-illumination time in the formation of halogenated homo- and copolymers has been examined. From different suitable copolymer system, after characterization of their glass transition temperatures, their curing behavior and their refractive indices as function of the monomer ratios, monomode waveguides applying PMMA substrates have been fabricated. To examine the materials composition also in the 6 X 6 micrometers 2 waveguides they have been visualized by transmission electron microscopy. With this method e.g. segregation phenomena could be observed in the waveguide cross section characterization as well. The optical losses in monomode waveguides caused by segregation and other materials induce defects like micro bubbles formed as a result of shrinkage have been quantized by return loss measurements. Defects causing scattering could be observed by convocal laser scanning microscopy and by conventional light microscopy.

  11. The influence of thermoplastic film interleaving on the interlaminar shear strength and mode 1 fracture of laminated composites

    SciTech Connect

    Li, L.; Liew, K.M. [Nanyang Technological Univ., Singapore (Singapore). School of Mechanical and Production Engineering; Lee-Sullivan, P. [Univ. of New Brunswick, Fredericton, New Brunswick (Canada). Dept. of Mechanical Engineering

    1996-07-01

    Results are presented on the interlaminar shear strength (ILSS) and Mode 1 fracture toughness (G{sub IC}) of glass/epoxy laminates interleaved with thermoplastic polyester films using four-point bending and double cantilever beam tests, respectively. The ILSS equation from classical beam theory was modified to account for the increased film thickness. It was found that the ultimate failure load and ILSS could be doubled if a thermoplastic film of high ductility but low glass transition temperature is used. Good film/composite ply adhesion is necessary. Mode 1 fracture toughness is influenced by film thickness and interleaving with a 0.2 mm thick film increased in the G{sub IC} by 40%. Interleaving with a thinner film (0.1 mm), however, resulted in adhesive failure and reduced fiber bridging.

  12. Poly(lactic acid) blends with desired end-use properties by addition of thermoplastic polyester elastomer and MDI

    Microsoft Academic Search

    Haydar U. Zaman; Jun Cheol Song; Lee-Soon Park; Inn-Kyu Kang; Soo-Young Park; Giseop Kwak; Byung-sik Park; Keun-Byoung Yoon

    2011-01-01

    The disadvantages of the poor mechanical properties of polylactic acid (PLA) limit its ability to be used in a wide number\\u000a of applications. Melt blending of PLA and thermoplastic polyester elastomer (TPEE) has been performed in an effort to toughen\\u000a the PLA without significant losses in modulus and ultimate tensile strength. In order to enhance the compatibility of PLA\\u000a and

  13. A Hybrid Non-Contact Ultrasonic System for Sensing Bond Quality in Tow-Placed Thermoplastic Composites

    Microsoft Academic Search

    Francesco Lanza Di Scalea; Robert E. Green

    2000-01-01

    A novel non-contact nondestructive evaluation system is proposed for sensing bond quality in tow-placed graphite\\/PEEK thermoplastic composites. The inspection tool consists of a hybrid ultrasonic system which employs laser generation of narrow-band surface waves with fiberoptic light delivery, and signal detection by air-coupled transduction. The fiberoptic link enhances flexibility and remoteness of the laser source from the test piece. The

  14. Properties of shape memory polyurethane used as a low-temperature thermoplastic biomedical orthotic material: influence of hard segment content

    Microsoft Academic Search

    Qinghao Meng; Jinlian Hu; Yong Zhu

    2008-01-01

    A series of PCL-based shape memory polyurethanes was synthesized via bulk pre-polymerization. Their thermal, mechanical properties, shape memory properties, softening and hardening processes were investigated by the experimental approach and made comparison with a commercially available orthotic material. The cytotoxicity of the low-temperature thermoplastic polyurethane was tested. The results suggest that the soft segment phase of the shape memory polyurethanes

  15. A Low-Temperature Thermoplastic Antibacterial Medical Orthotic Material Made of Shape Memory Polyurethane Ionomer: Influence of Ionic Group

    Microsoft Academic Search

    Qinghao Meng; Jinlian Hu; Baohua Liu; Yong Zhu

    2009-01-01

    PCL-based shape memory polyurethane ionomers with quaternarized pyridine moieties incorporated through molecular extension were synthesized. These polyurethanes were specifically designed as low-temperature thermoplastic anti-bacterial orthotic materials. A commercialized orthotic material was employed for comparison. The influence of ionic groups on the properties of orthotic materials was studied. The anti-bacterial properties and cytotoxicity of the polyurethane ionomer were tested. It was

  16. Shape memory effect of thermoplastic segmented polyurethanes with self-complementary quadruple hydrogen bonding in soft segments

    Microsoft Academic Search

    Yong Zhu; Jinlian Hu; Yijun Liu

    2009-01-01

    This paper describes the fact that a kind of thermoplastic shape memory polyurethane with self-complementary quadruple hydrogen\\u000a bonding units in soft segments can present a significant shape memory effect under the usually used thermodynamic programming\\u000a condition. Compared with the control sample, it was observed that the introduction of self-complementary quadruple hydrogen\\u000a bonding into soft segments increases the glass transition temperature

  17. Cost effective manufacturing process of thermoplastic matrix composites for the traditional industry: the example of a carbon-fiber reinforced thermoplastic flywheel

    Microsoft Academic Search

    C. A Mahieux

    2001-01-01

    Composite materials were successfully introduced and are now widely used for aerospace applications. Due to their high specific strength and stiffness, polymer-based composite materials should also be attractive candidates for many products of the traditional industries such as gas turbines, oil industry, or water and gas piping. The introduction of composite materials in the traditional industry is however a very

  18. From Commodity Polymers to Functional Polymers

    PubMed Central

    Xiang, Tao; Wang, Ling-Ren; Ma, Lang; Han, Zhi-Yuan; Wang, Rui; Cheng, Chong; Xia, Yi; Qin, Hui; Zhao, Chang-Sheng

    2014-01-01

    Functional polymers bear specified chemical groups, and have specified physical, chemical, biological, pharmacological, or other uses. To adjust the properties while keeping material usage low, a method for direct synthesis of functional polymers is indispensable. Here we show that various functional polymers can be synthesized by in situ cross-linked polymerization/copolymerization. We demonstrate that the polymers synthesized by the facile method using different functional monomers own outstanding pH-sensitivity and pH-reversibility, antifouling property, antibacterial, and anticoagulant property. Our study opens a route for the functionalization of commodity polymers, which lead to important advances in polymeric materials applications. PMID:24710333

  19. Architecture of nanostructured polymers

    Microsoft Academic Search

    Koji Ishizu; Keiichiro Tsubaki; Akihide Mori; Satoshi Uchida

    2003-01-01

    This paper reviews the synthesis and properties of nanostructural polymers with different macromolecular architecture. Special emphasis is placed on hyperbranched polymers, rod-like macromolecules and polymer brushes. Hyperbranched polymers were prepared by various types of living radical mechanisms of functionalized vinyl monomers and showed hard sphere-like behavior in dilute solution with increasing degree of branching. This reflected on the compact nature

  20. Nanoparticle and gelation stabilized functional composites of an ionic salt in a hydrophobic polymer matrix.

    PubMed

    Kanyas, Selin; Ayd?n, Derya; Kizilel, Riza; Demirel, A Levent; Kizilel, Seda

    2014-01-01

    Polymer composites consisted of small hydrophilic pockets homogeneously dispersed in a hydrophobic polymer matrix are important in many applications where controlled release of the functional agent from the hydrophilic phase is needed. As an example, a release of biomolecules or drugs from therapeutic formulations or release of salt in anti-icing application can be mentioned. Here, we report a method for preparation of such a composite material consisted of small KCOOH salt pockets distributed in the styrene-butadiene-styrene (SBS) polymer matrix and demonstrate its effectiveness in anti-icing coatings. The mixtures of the aqueous KCOOH and SBS-cyclohexane solutions were firstly stabilized by adding silica nanoparticles to the emulsions and, even more, by gelation of the aqueous phase by agarose. The emulsions were observed in optical microscope to check its stability in time and characterized by rheological measurements. The dry composite materials were obtained via casting the emulsions onto the glass substrates and evaporations of the organic solvent. Composite polymer films were characterized by water contact angle (WCA) measurements. The release of KCOOH salt into water and the freezing delay experiments of water droplets on dry composite films demonstrated their anti-icing properties. It has been concluded that hydrophobic and thermoplastic SBS polymer allows incorporation of the hydrophilic pockets/phases through our technique that opens the possibility for controlled delivering of anti-icing agents from the composite. PMID:24516593

  1. Effects of fiber pre-strain on the healing efficiency of thermoset polymers

    NASA Astrophysics Data System (ADS)

    Ajisafe, Oludayo

    One major challenge that has been facing material self healing is how to heal bigger macroscopic or structural scale damage autonomously, repeatedly, efficiently and at molecular length scale. Different approaches have been used to heal materials. However, none of them can heal macroscopic cracks. Our research group has proposed a novel shape-memory polymer (SMP) based, bio-inspired Close-Then-Heal (CTH) scheme to heal macroscopic cracks in SMP matrix. The most recent development in our group is to use SMP fibers to heal conventional thermosetting polymers according to the CTH scheme. The aim of this study is to further investigate the effect of pre-tension of SMP fibers during the cold-drawing programming on the self-healing efficiency of the conventional thermosetting polymer composites. This was done by fabricating a composite with thermoplastic particles (polycaprolactone) dispersed in a thermosetting polymer matrix (Epon 828). Shape memory fiber pre-tensioned into 3 different groups of 0%, 50% and 100% prestrain, was also embedded into the composite in the longitudinal direction. In this composite, the shape memory effect of the shape memory fibers is utilized for sealing (closing) the cracks and the thermoplastic particles are used for molecular-length scale healing. In this study, 7% by volume of thermoplastic particles was used. Beam specimens were prepared and controlled structural length scale damage was created prior to curing by inserting an aluminum foil of designed thickness in a perpendicular direction to the shape memory fibers before the matrix was allowed to cure. The aluminum sheet was removed post cure to leave a controlled damage. The specimen was healed by fixing the two ends of the beam and heating the sample above the Tg of the shape memory fiber. The recovery force of the sample was recorded and then the beam was tested again to fracture. This fracture healing cycle lasted 7 times. The healing efficiency was evaluated per the peak-tensile load. The Ultrasonic C-scan and SEM were used to examine the healed cracks. It was found that the beams with 100% pre-strained fiber were able to recover repeatedly about 50% of its peak tensile strength; the beams with 50% pre-strained fiber, 43%; and the beams with un-stretched fibers were able to recover about 21% of its original peak tensile strength. Also it was found that the higher the pre-tension the higher the recovery stress seen during the healing cycle.

  2. Solvent-free thermoplastic-poly(dimethylsiloxane) bonding mediated by UV irradiation followed by gas-phase chemical deposition of an adhesion linker

    NASA Astrophysics Data System (ADS)

    Ahn, S. Y.; Lee, N. Y.

    2015-07-01

    Here, we introduce a solvent-free strategy for bonding various thermoplastic substrates with poly(dimethylsiloxane) (PDMS) using ultraviolet (UV) irradiation followed by the gas-phase chemical deposition of aminosilane on the UV-irradiated thermoplastic substrates. The thermoplastic substrates were first irradiated with UV for surface hydrophilic treatment and were then grafted with vacuum-evaporated aminosilane, where the alkoxysilane side reacted with the oxidized surface of the thermoplastic substrate. Next, the amine-terminated thermoplastic substrates were treated with corona discharge to oxidize the surface and were bonded with PDMS, which was also oxidized via corona discharge. The two substrates were then hermetically sealed and pressed under atmospheric pressure for 30?min at 60?°C. This process enabled the formation of a robust siloxane bond (Si–O–Si) between the thermoplastic substrate and PDMS under relatively mild conditions using an inexpensive and commercially available UV lamp and Tesla coil. Various thermoplastic substrates were examined for bonding with PDMS, including poly(methylmethacrylate) (PMMA), polycarbonate (PC), poly(ethyleneterephthalate) (PET) and polystyrene (PS). Surface characterizations were performed by measuring the contact angle and performing x-ray photoelectron spectroscopy analysis, and the bond strength was analyzed by conducting various mechanical force measurements such as pull, delamination, leak and burst tests. The average bond strengths for the PMMA–PDMS, PC–PDMS, PET–PDMS and PS–PDMS assemblies were measured at 823.6, 379.3, 291.2 and 229.0?kPa, respectively, confirming the highly reliable performance of the introduced bonding strategy.

  3. Use of Supercritical Carbon Dioxide in the Processing of Thermoplastic Elastomer Nanocomposites

    Microsoft Academic Search

    Zijin Zhuang

    2009-01-01

    Polymer-layered silicate (PLS) nanocomposites are of great interest presently due to their\\u000asignificant enhancement of properties compared to conventional polymeric materials. However, achieving a high extent of exfoliation, which refers to the complete separation and uniform dispersion of clay layers, is a key challenge in the preparation of PLS nanocomposites, particular for non-polar polymers like polyolefins. Recently, several novel processing

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

    NASA Astrophysics Data System (ADS)

    Masoomi, Mohsen; Katbab, Ali Asghar; Nazockdast, Hossein

    2006-09-01

    Attempts have been made for the first time to prepare a friction material with the characteristic of thermal sensitive modulus, by the inclusion of thermoplastic elastomers (TPE) as viscoelastic polymeric materials into the formulation in order to the increase the damping behavior of the cured friction material. Styrene butadiene styrene (SBS), styrene ethylene butylene styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend system were used as TPE materials. In order to evaluate the viscoelastic parameters such as loss factor (tan ?) and storage modulus (E?) for the friction material, dynamic mechanical analyzer (DMA) were used. Natural frequencies and mode shapes of friction material and brake disc were determined by modal analysis. However, NBR/PVC and SEBS were found to be much more effective in damping behavior. The results from this comparative study suggest that the damping characteristics of commercial friction materials can be strongly affected by the TPE ingredients. This investigation also confirmed that the specimens with high TPE content had low noise propensity.

  5. Structure and properties of thermoplastic polyurethanes based on poly(dimethylsiloxane): assessment of biocompatibility.

    PubMed

    Pergal, Marija V; Nestorov, Jelena; Tovilovi?, Gordana; Ostoji?, Sanja; Go?evac, Dejan; Vasiljevi?-Radovi?, Dana; Djonlagi?, Jasna

    2014-11-01

    Properties and biocompatibility of a series of thermoplastic poly(urethane-siloxane)s (TPUSs) based on ?,?-dihydroxy ethoxy propyl poly(dimethylsiloxane) (PDMS) for potential biomedical application were studied. Thin films of TPUSs with a different PDMS soft segment content were characterized by (1) H NMR, quantitative (13) C NMR, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), contact angle, and water absorption measurements. Different techniques (FTIR, AFM, and DMA) showed that decrease of PDMS content promotes microphase separation in TPUSs. Samples with a higher PDMS content have more hydrophobic surface and better waterproof performances, but lower degree of crystallinity. Biocompatibility of TPUSs was examined after attachment of endothelial cells to the untreated copolymer surface or surface pretreated with multicomponent protein mixture, and by using competitive protein adsorption assay. TPUSs did not exhibit any cytotoxicity toward endothelial cells, as measured by lactate dehydrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assays. The untreated and proteins preadsorbed TPUS samples favored endothelial cells adhesion and growth, indicating good biocompatibility. All TPUSs adsorbed more albumin than fibrinogen in competitive protein adsorption experiment, which is feature regarded as beneficial for biocompatibility. The results indicate that TPUSs have good surface, thermo-mechanical, and biocompatible properties, which can be tailored for biomedical application requirements by adequate selection of the soft/hard segments ratio of the copolymers. PMID:24376027

  6. Water proof and strength retention properties of thermoplastic starch based biocomposites modified with glutaraldehyde.

    PubMed

    Yeh, Jen-Taut; Hou, Yuan-Jing; Cheng, Li; Wang, Ya-Zhou; Yang, Liang; Wang, Chuen-Kai

    2015-08-20

    Water proof and strength retention properties of thermoplastic starch (TPS) resins were successfully improved by reacting glutaraldehyde (GA) with starch molecules during their gelatinization processes. Tensile strength (?f) values of initial and aged TPS100BC0.02GAx and (TPS100BC0.02GAx)75PLA25 specimens improved significantly to a maximal value as GA contents approached an optimal value, while their moisture content and elongation at break values reduced to a minimal value, respectively, as GA contents approached the optimal value. The ?f retention values of (TPS100BC0.02GA0.5)75PLA25 specimen aged for 56 days are more than 50 times higher than those of correspoding aged TPS and TPS100BC0.02 specimens, respectively. New melting endotherms and diffraction peaks of VH-type starch crystals were found on DSC thermograms and WAXD patterns of aged TPS or TPS100BC0.02 specimens, respectively, while negligible retrogradation effect was found for most aged TPS100BC0.02GAx and/or (TPS100BC0.02GAx)75PLA25 specimens. PMID:25965466

  7. Screening of matrices and fibers for reinforced thermoplastics intended for dental applications.

    PubMed

    Goldberg, A J; Burstone, C J; Hadjinikolaou, I; Jancar, J

    1994-02-01

    Plastics reinforced with continuous fibers (FRC) are being developed for dental applications, such as prosthodontic frameworks and orthodontic retainers. Flexure properties, stress relaxation and hydrolytic stability of FRC based on six thermoplastic matrices, three types of fibers, and three fiber volume fractions were evaluated. Samples with clinically relevant dimensions were tested. Polycarbonate was the preferred matrix material. Polycarbonate reinforced with 42 volume percent glass fibers exhibited the highest combination of flexure modulus (17.9 +/- 2.6 GPa), flexure strength (426 +/- 40 MPa), reinforcing efficiency (0.79), and resistance to stress relaxation. No statistically significant difference was observed between E and S2 glass reinforced composites under the experimental conditions used. Kevlar reinforced materials exhibited a low flexure modulus and strength. The apparent flexure moduli of all composites decreased with span length in the range of clinical interest. Generally, the prevalent mode of failure for all FRC investigated was brittle failure under flexure loading. Relatively large sample-to-sample variation in both composition and properties indicated that improved fabrication methods will be needed in future studies. The combination of good flexure properties, formability, and translucency suggests that novel appliance designs for dentistry are feasible with FRC, but further studies of its properties and particularly the effects of fiber/matrix interfacial quality are needed. PMID:8207027

  8. Real-Time Small-Angle X-ray Scattering from Rubber-Modified Thermoplastics

    NASA Astrophysics Data System (ADS)

    Bubeck, R. A.

    1997-03-01

    Real-time small-angle X-ray scattering (RTSAXS) studies have been performed on a series of rubber-modified thermoplastics. These include: High Impact Polystyrene (HIPS), (2) Acrylonitrile Butadiene Styrene copolymers (ABS), (3) weatherable ABS-type resins containing grafted rubber particles derived from acrylonitrile ethylene styrene (AES) or acrylonitrile styrene acrylate (ASA), and (4) rubber-toughened syndiotactic polystyrene (sPS). Scattering patterns were measured at successive time intervals of from 2 to 3 ms. and were analyzed to determine the plastic strain due to crazing. Simultaneous measurements of the absorption of the primary beam by the sample allowed the total plastic strain to be computed. The plastic strain due to other deformation mechanisms (e.g. particle cavitation and macroscopic shear deformation) was determined by the difference. The contribution from microscopic shear deformation was determined from video-based optical data obtained along with the RTSAXS data. One example is an experimental AES system in an SAN matrix with insufficient gel particle graft which was found to lack substantial contributions from crazing and microshear yielding mechanisms. Manipulating the graft and cross linking levels in the AES system results in a ten-fold increase in microshear yield, but not much additional cavitation and crazing.

  9. Impact damage characterization in cross-plied carbon fiber/thermoplastic composites using thermoelastic stress analysis

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Uenoya, T.; Miyamoto, H.

    2012-04-01

    Carbon fiber (CF)-plastic composites are expected from the view point of light weighting vehicle structures. The CF/thermoset plastic laminates have low damage resistance to out-of-plane impact as a problem to be solved, because they behave as a low strength inter-laminar as compared with high-strength in fiber direction. Accordingly it is strongly desired to develop CF-composite materials based thermoplastics that have higher toughness than thermoset, for vehicle use. The present paper describes investigation of impact damages through thermoelastic stress analysis (TSA). Lowvelocity impact test using drop weight was conducted on stitched non-crimp-fabric CF/NY6 composite specimens. Stress distribution of the specimens under impact loading was monitored by a lock-in thermography system from the opposite side of the impact direction. The instrumentation system, which had a focal plane array detector, provided a succession of thermoelastic stress information as a sequence of TSA images at a high rate. The measured stress distribution agreed well with a theoretical. And also, selecting a contour feature of the stress distribution determined with a suitable level conformed approximately to the internal damage image that was processed from the TSA images obtained before and after impact.

  10. High strength thermoplastic composite hybrids containing random and oriented fiber reinforcements

    SciTech Connect

    Kao, M.; Kovacich, A.; Marshall, D.; Schachner, K. [Johnson Controls, Inc., Milwaukee, WI (United States)

    1997-12-31

    Polypropylene-based composites containing hybrid reinforcements of random and oriented fibers were developed by combining Glass Mat Thermoplastic (GMT) composite sheets with thin tapes containing unidirectional fibers. The idea of this construction is to use GMT to form the basic shape of a composite structure while adding oriented tape at strategic locations for additional reinforcement according to the load requirement. Compression molding was used to laminate GMT sheets and oriented tapes in various combinations of tape arrangement. Room temperature bending tests showed that beam deflection could be improved by 33% when it was reinforced with one layer of the glass tape on the tension side and up to 71% when reinforced with one layer each of the carbon tape on the tension and compression sides. Finite Element Analyses showed the deflection of hybrid beams under different loading conditions agreed well with the experimental data. The hybrid concept was also successfully applied to an automotive seat cushion frame in which glass and carbon tapes were molded-in at the high stress area under production conditions, indicating that this concept is both feasible and practical for automotive structural applications.

  11. Smoke suppression properties of ferrite yellow on flame retardant thermoplastic polyurethane based on ammonium polyphosphate.

    PubMed

    Chen, Xilei; Jiang, Yufeng; Jiao, Chuanmei

    2014-02-15

    This article mainly studies smoke suppression properties and synergistic flame retardant effect of ferrite yellow (FeOOH) on flame retardant thermoplastic polyurethane (TPU) composites using ammonium polyphosphate (APP) as a flame retardant agent. Smoke suppression properties and synergistic flame retardant effect of FeOOH on flame retardant TPU composites were intensively investigated by smoke density test (SDT), cone calorimeter test (CCT), scanning electron microscopy (SEM), and thermal-gravimetric analysis (TGA). Remarkably, the SDT results show that FeOOH can effectively decrease the amount of smoke production with or without flame. On the other hand, the CCT data reveal that the addition of FeOOH can apparently reduce heat release rate (HRR), total heat release (THR), and total smoke release (TSR), etc. Here, FeOOH is considered to be an effective smoke suppression agent and a good synergism with APP in flame retardant TPU composites, which can greatly improve the structure of char residue realized by TGA and SEM results. PMID:24389005

  12. Thermal Edge-Effects Model for Automated Tape Placement of Thermoplastic Composites

    NASA Technical Reports Server (NTRS)

    Costen, Robert C.

    2000-01-01

    Two-dimensional thermal models for automated tape placement (ATP) of thermoplastic composites neglect the diffusive heat transport that occurs between the newly placed tape and the cool substrate beside it. Such lateral transport can cool the tape edges prematurely and weaken the bond. The three-dimensional, steady state, thermal transport equation is solved by the Green's function method for a tape of finite width being placed on an infinitely wide substrate. The isotherm for the glass transition temperature on the weld interface is used to determine the distance inward from the tape edge that is prematurely cooled, called the cooling incursion Delta a. For the Langley ATP robot, Delta a = 0.4 mm for a unidirectional lay-up of PEEK/carbon fiber composite, and Delta a = 1.2 mm for an isotropic lay-up. A formula for Delta a is developed and applied to a wide range of operating conditions. A surprise finding is that Delta a need not decrease as the Peclet number Pe becomes very large, where Pe is the dimensionless ratio of inertial to diffusive heat transport. Conformable rollers that increase the consolidation length would also increase Delta a, unless other changes are made, such as proportionally increasing the material speed. To compensate for premature edge cooling, the thermal input could be extended past the tape edges by the amount Delta a. This method should help achieve uniform weld strength and crystallinity across the width of the tape.

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    We present a combined experimental/theoretical study aimed at enhancing adhesion between a NiTi wire and a thermoplastic polyolefin (TPO) matrix in which it is embedded. NiTi wire surfaces were subjected to the following surface treatments prior to pull-out tests: (i) treatment with an acid etch or chemical conversion coating and (ii) application of a surface microgeometry to enhance mechanical interlocking between the wire and the TPO matrix. Nanometer to micron-scale NiTi wire surface features were examined with atomic force microscopy. The extent to which each treatment increased the pull-out force was quantified. Existing theoretical models of wire pull-out based upon strength of materials and linear elastic fracture mechanics are reviewed. Results from a finite element model (FEM), wherein the NiTi/TPO matrix interface is modeled with a cohesive zone model, suggest that the interface behavior strongly depends on the cohesive energy. The FEM model properly accounts for energy dissipation at the debonding front and inelastic deformation in a NiTi wire during pull-out. We demonstrate that residual stresses from the molding process significantly influence mode mixity at the debonding front.

  14. Properties and fibroblast cellular response of soft and hard thermoplastic polyurethane electrospun nanofibrous scaffolds.

    PubMed

    Mi, Hao-Yang; Jing, Xin; Salick, Max R; Cordie, Travis M; Peng, Xiang-Fang; Turng, Lih-Sheng

    2015-07-01

    Soft and hard thermoplastic polyurethane (TPU) and their blends were electrospun to fabricate nanofibrous scaffolds with various properties in order to investigate the substrate property effects on cellular response. The scaffolds were characterized with Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, water contact angle tests, and protein absorption tests. It was found that the hard segment content in the scaffold increased with the hard TPU ratio, which resulted in improved hydrophobicity and decreased over all protein absorption. 3T3 fibroblasts were cultured on those scaffolds to investigate the cellular response. On soft TPU scaffolds, the cells formed were round in shape and aggregated into clusters. However, on hard TPU scaffolds, the cells exhibited a spindle shape and spread out on the scaffolds, indicating preferred cell-substrate interaction. The cell viability and proliferation of cells on hard scaffolds were higher than on soft scaffolds and on 50% hard/50% soft scaffolds. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 960-970, 2015. PMID:25176285

  15. Long FBG sensor characterization of residual strains in AS4/PPS thermoplastic laminates

    NASA Astrophysics Data System (ADS)

    Sorensen, Larissa K.; Gmur, Thomas; Botsis, John

    2004-07-01

    The consolidation of thermoplastic composites produces internal residual strains due to the differences between the coefficients of thermal expansion of the component materials. In the case of AS4/PPS (carbon fibre-polyphenylene sulphide), where the melting/solidification temperature is 280°C, there exists a 255°C range wherein the various constituents will contract/expand to different degrees. A fibre Bragg grating (FBG) sensor may be embedded into this laminate with the goal of characterizing the residual strains; however, these strains may be non-uniform in the longitudinal and transverse directions, and may also vary depending on the laminate architecture. Non-uniform axial strains typically broaden and split the FBG sensor's spectral response, making it difficult to measure the strain distribution. Also, load-induced birefringence caused by the consolidation process will complicate the interpretation of the spectral response. This research is directed at understanding the residual strain state in FBG sensors due to the fabrication process. It is the aim of this study to experimentally investigate the residual strains in long and short gauge length FBG sensors embedded in the 0° plies of AS4/PPS unidirectional and cross-ply laminates (200 x 50 x 3.6 mm). Long gauge length sensors are monitored throughout the fabrication process, to provide insight into the development of the residual strains.

  16. Micromechanical modeling of short glass-fiber reinforced thermoplastics-Isotropic damage of pseudograins

    NASA Astrophysics Data System (ADS)

    Kammoun, S.; Brassart, L.; Robert, G.; Doghri, I.; Delannay, L.

    2011-05-01

    A micromechanical damage modeling approach is presented to predict the overall elasto-plastic behavior and damage evolution in short fiber reinforced composite materials. The practical use of the approach is for injection molded thermoplastic parts reinforced with short glass fibers. The modeling is proceeded as follows. The representative volume element is decomposed into a set of pseudograins, the damage of which affects progressively the overall stiffness and strength up to total failure. Each pseudograin is a two-phase composite with aligned inclusions having same aspect ratio. A two-step mean-field homogenization procedure is adopted. In the first step, the pseudograins are homogenized individually according to the Mori-Tanaka scheme. The second step consists in a self-consistent homogenization of homogenized pseudograins. An isotropic damage model is applied at the pseudograin level. The model is implemented as a UMAT in the finite element code ABAQUS. Model is shown to reproduce the strength and the anisotropy (Lankford coefficient) during uniaxial tensile tests on samples cut under different directions relative to the injection flow direction.

  17. Micromechanical modeling of short glass-fiber reinforced thermoplastics-Isotropic damage of pseudograins

    SciTech Connect

    Kammoun, S.; Brassart, L.; Doghri, I.; Delannay, L. [Universite catholique de Louvain, institute of Mechanics, Materials and Civil Engineering (iMMC), 4, av. G. Lemaitre, B-1348 Louvain-la-Neuve (Belgium); Robert, G. [Rhodia Engineering Plastics, Avenue Ramboz, B.P. 64, 69192 Saint-FONS Cedex (France)

    2011-05-04

    A micromechanical damage modeling approach is presented to predict the overall elasto-plastic behavior and damage evolution in short fiber reinforced composite materials. The practical use of the approach is for injection molded thermoplastic parts reinforced with short glass fibers. The modeling is proceeded as follows. The representative volume element is decomposed into a set of pseudograins, the damage of which affects progressively the overall stiffness and strength up to total failure. Each pseudograin is a two-phase composite with aligned inclusions having same aspect ratio. A two-step mean-field homogenization procedure is adopted. In the first step, the pseudograins are homogenized individually according to the Mori-Tanaka scheme. The second step consists in a self-consistent homogenization of homogenized pseudograins. An isotropic damage model is applied at the pseudograin level. The model is implemented as a UMAT in the finite element code ABAQUS. Model is shown to reproduce the strength and the anisotropy (Lankford coefficient) during uniaxial tensile tests on samples cut under different directions relative to the injection flow direction.

  18. DAMAGE MODELING OF INJECTION-MOLDED SHORT- AND LONG-FIBER THERMOPLASTICS

    SciTech Connect

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

    2009-10-30

    This article applies the recent anisotropic rotary diffusion – reduced strain closure (ARD-RSC) model for predicting fiber orientation and a new damage model for injection-molded long-fiber thermoplastics (LFTs) to analyze progressive damage leading to total failure of injection-molded long-glass-fiber/polypropylene (PP) specimens. The ARD-RSC model was implemented in a research version of the Autodesk Moldflow Plastics Insight (MPI) processing code, and it has been used to simulate injection-molding of a long-glass-fiber/PP plaque. The damage model combines micromechanical modeling with a continuum damage mechanics description to predict the nonlinear behavior due to plasticity coupled with damage in LFTs. This model has been implemented in the ABAQUS finite element code via user-subroutines and has been used in the damage analyses of tensile specimens removed from the injection-molded long-glass-fiber/PP plaques. Experimental characterization and mechanical testing were performed to provide input data to support and validate both process modeling and damage analyses. The predictions are in agreement with the experimental results.

  19. Studies on the effect of storage time and plasticizers on the structural variations in thermoplastic starch.

    PubMed

    Schmitt, H; Guidez, A; Prashantha, K; Soulestin, J; Lacrampe, M F; Krawczak, P

    2015-01-22

    Starch was combined with plasticizers such as glycerol, sorbitol, glycerol/sorbitol and urea/ethanolamine blends by means of high shear extrusion process to prepare thermoplastic starch (TPS). Effect of storage time and plasticizers on the structural stability of melt processed TPS was investigated. Morphological observation, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy reveal that melt extrusion process is efficient in transforming granular starch into a plasticized starch for all plasticizer compositions. XRD analysis highlights major changes in the microstructure of plasticized starch, and dependence of crystalline type and degree of crystallinity mainly on the plasticizer composition and storage time. Dynamical mechanical analysis (DMA) yields a decrease of the peak intensity of loss factor with aging time. The effect of ageing on tensile strength also appears to be highly dependent on the plasticizer composition. Thus, through different plasticizer combinations and ageing, starch-based materials with significant differences in tensile properties can be obtained, which may be tuned to meet the requirements of a wide range of applications. PMID:25439906

  20. New melt-processable thermoplastic polyimides for opto-electronic applications

    NASA Astrophysics Data System (ADS)

    Narayanan, Aditya; Haralur, Gurulingamurthy

    2012-10-01

    The rapid development and adoption of digital technology is leading to an increase in demand for smaller, faster digital data devices and faster digital telecommunication networks. This trend requires increased network bandwidth to handle large amounts of data and seamless integration of network devices with compatible end-user devices. This need is being met by using fiber-optic and photonics technology, infra-red (IR) signals to transmit information, and is fundamental changing the communication industry, thereby creating a need for new polymeric materials. New ULTEM* polyetherimide (PEI) and EXTEM* thermoplastic polyimide (TPI) resins meet the material requirements for the optoelectronics industry. These resins have building blocks enabling IR light transmission without degrading signal quality. They can be injection-molded into thin, precision optical lenses and connectors. ULTEM* resins are been widely used in this industry as fiber-optic components in trans-receivers. EXTEM* resins are amenable to lead-free soldering (LFS), a greener industrial assembly process. While still being IR-transparent, EXTEM* resin is an ideal material for LFS capable substrates, connectors and lenses. An optical product portfolio has been developed and is being presented as a solution to the opto-electronics component industry and some of the successful applications therein.

  1. Healable thermoset polymer composite embedded with stimuli-responsive fibres.

    PubMed

    Li, Guoqiang; Meng, Harper; Hu, Jinlian

    2012-12-01

    Severe wounds in biological systems such as human skin cannot heal themselves, unless they are first stitched together. Healing of macroscopic damage in thermoset polymer composites faces a similar challenge. Stimuli-responsive shape-changing polymeric fibres with outstanding mechanical properties embedded in polymers may be able to close macro-cracks automatically upon stimulation such as heating. Here, a stimuli-responsive fibre (SRF) with outstanding mechanical properties and supercontraction capability was fabricated for the purpose of healing macroscopic damage. The SRFs and thermoplastic particles (TPs) were incorporated into regular thermosetting epoxy for repeatedly healing macroscopic damages. The system works by mimicking self-healing of biological systems such as human skin, close (stitch) then heal, i.e. close the macroscopic crack through the thermal-induced supercontraction of the SRFs, and bond the closed crack through melting and diffusing of TPs at the crack interface. The healing efficiency determined using tapered double-cantilever beam specimens was 94 per cent. The self-healing process was reasonably repeatable. PMID:22896563

  2. Thermo-mechanical Characterization of Metal/Polymer Composite Filaments and Printing Parameter Study for Fused Deposition Modeling in the 3D Printing Process

    NASA Astrophysics Data System (ADS)

    Hwang, Seyeon; Reyes, Edgar I.; Moon, Kyoung-sik; Rumpf, Raymond C.; Kim, Nam Soo

    2015-03-01

    New metal/polymer composite filaments for fused deposition modeling (FDM) processes were developed in order to observe the thermo-mechanical properties of the new filaments. The acrylonitrile butadiene styrene (ABS) thermoplastic was mixed with copper and iron particles. The percent loading of the metal powder was varied to confirm the effects of metal particles on the thermo-mechanical properties of the filament, such as tensile strength and thermal conductivity. The printing parameters such as temperature and fill density were also varied to see the effects of the parameters on the tensile strength of the final product which was made with the FDM process. As a result of this study, it was confirmed that the tensile strength of the composites is decreased by increasing the loading of metal particles. Additionally, the thermal conductivity of the metal/polymer composite filament was improved by increasing the metal content. It is believed that the metal/polymer filament could be used to print metal and large-scale 3-dimensional (3D) structures without any distortion by the thermal expansion of thermoplastics. The material could also be used in 3D printed circuits and electromagnetic structures for shielding and other applications.

  3. Engineering Polymer Informatics

    E-print Network

    Adams, Nico; Ryder, Jennifer; Jessop, David M; Corbett, Peter; Murray-Rust, Peter

    2007-12-17

    Engineering Polymer Informatics Nico Adams, Jen Ryder, Nicholas England, David Jessop, Peter Corbett, Peter Murray-Rust Our mission is to develop an informatics toolbox, which will take into account the special computational needs of polymers...

  4. Polymer composites containing nanotubes

    NASA Technical Reports Server (NTRS)

    Bley, Richard A. (Inventor)

    2008-01-01

    The present invention relates to polymer composite materials containing carbon nanotubes, particularly to those containing singled-walled nanotubes. The invention provides a polymer composite comprising one or more base polymers, one or more functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers and carbon nanotubes. The invention also relates to functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers, particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having side chain functionalization, and more particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having olefin side chains and alkyl epoxy side chains. The invention further relates to methods of making polymer composites comprising carbon nanotubes.

  5. Polymer Fluid Dynamics.

    ERIC Educational Resources Information Center

    Bird, R. Byron

    1980-01-01

    Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

  6. Selective light sintering of Aerosol-Jet printed silver nanoparticle inks on polymer substrates

    SciTech Connect

    Schuetz, K., E-mail: klaus.schuetz1@gmx.de, E-mail: hoerber@faps.uni-erlangen.de, E-mail: franke@faps.uni-erlangen.de; Hoerber, J., E-mail: klaus.schuetz1@gmx.de, E-mail: hoerber@faps.uni-erlangen.de, E-mail: franke@faps.uni-erlangen.de; Franke, J., E-mail: klaus.schuetz1@gmx.de, E-mail: hoerber@faps.uni-erlangen.de, E-mail: franke@faps.uni-erlangen.de [Institute for Factory Automation and Production Systems, University of Erlangen-Nuremberg (Germany)

    2014-05-15

    Printing silver nanoparticle inks to generate conductive structures for electronics on polymer substrates has gained increasing relevance in recent years. In this context, the Aerosol-Jet Technology is well suited to print silver ink on 3D-Molded Interconnect Devices (MID). The deposited ink requires thermal post-treatment to obtain sufficient electrical conductivity and adhesion. However, commonly used oven sintering cannot be applied for many thermoplastic substrates due to low melting temperatures. In this study a new sintering technology, selective light sintering, is presented, based on the focused, continuous light beam of a xenon lamp. Sintering experiments were conducted with Aerosol-Jet printed structures on various polycarbonate (PC) substrates. Especially on neat, light transparent PC, silver tracks were evenly sintered with marginal impact to the substrate. Electrical conductivities significantly exceed the values obtained with conventional oven sintering. Adhesive strength is sufficient for conductive tracks. Experiments with non-transparent PC substrates led to substrate damage due to increased light absorption. Therefore a concept for a variation of light sintering was developed, using optical filters. First experiments showed significant reduction of substrate damage and good sintering qualities. The highly promising results of the conducted experiments provide a base for further investigations to increase adhesion and qualifying the technology for MID applications and a broad spectrum of thermoplastic substrates.

  7. Polymer Hydrogels: A Review

    Microsoft Academic Search

    Waham Ashaier Laftah; Shahrir Hashim; Akos N. Ibrahim

    2011-01-01

    This review encompasses definitions, classification, main properties, and application of polymer hydrogels. Raw materials and preparation techniques of polymer hydrogels were described. The factors that affect absorption capacity and swelling properties of polymer hydrogels were reviewed. PHG materials are defined as a viscoelastic network structure, swellable and not soluble in water with high absorbent capacity, which may reach 1000 g\\/g of

  8. Responsive Polymer Brushes

    Microsoft Academic Search

    Sergiy Minko

    2006-01-01

    The review focuses on responsive\\/switching behavior of polymer brushes. The structure of the polymer brushes is analyzed in terms of the constitution and conformation of polymer chains. Responsive properties are widely discussed based on phase transition mechanisms in a controlled environment when changes are induced by solvent quality, temperature, concentration of ions, and interactions with liquids and solids. Potential applications

  9. Polymer supply chain management

    Microsoft Academic Search

    Sukran Kadipasaoglu; Jennifer Captain; Mark James

    2008-01-01

    A typical polymer supply chain network includes multiple plants, large number of storage terminals, customers and consignment locations, and complex distribution requirements. Here, we describe the complexity of polymer supply chain from 'logical positivist\\/empiricist' viewpoint based on in-depth interviews with supply chain managers of four major polymer manufacturers and on our experience in the industry. We begin by defining marketplace

  10. Polymers for engineering applications

    Microsoft Academic Search

    1987-01-01

    This book provides an introduction to the world of engineering plastics. It discusses the polymers, their properties strengths and limitations. There are 11 chapters, organized so that each chapter builds on the knowledge of the previous material. Coverage includes important polymer concepts, such as molecular structure, bonding, morphology and molecular weight, and polymer properties, such as thermal expansion, thermal transition,

  11. Ionic liquids as lubricants of metal-polymer contacts. Preparation and properties of the first dispersions of ionic liquids and nanoparticles in polymers

    NASA Astrophysics Data System (ADS)

    Sanes Molina, Jose

    Room-temperature ionic liquids (ILs) are high performance fluids that stand out because of a wide range of functional properties and exhibit a great potential for engineering applications. Although they have been employed as lubricants in metal-metal, metal-ceramic and ceramic-ceramic contacts, in this thesis we present the first study about the use of ILs as pure lubricants in polymer/steel contacts. The tests have established the efficacy of the ILs to reduce friction coefficient and wear rates in a variety of kinds of contacts, and criogenic to high temperature performance. Novel dispersions of ILs in polymers have been obtained with epoxy resin and thermoplastics as matrix. Therefore, the thermal, mechanical and tribological properties of the materials have studied and are discussed in the present thesis. Furthermore, the contents of ILs in the polymer matrix have been studied in relation to the tribological properties using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectrometry (EDS), the wear mechanisms that operated in the contacts were established. The novel dispersions showed a reduction in the friction coefficient and wear in comparison with neat polymers, reaching in some cases a decrease of 79%. In the case of thermoplastics such as polystyrene and polyamide 6, the new dispersions showed a reduction in friction coefficient and wear in the same range as that of the ILs when used as external lubricants in the steel/polymer contact. In addition nanoparticles of zinc oxide were used to obtain polycarbonate based nanohybrids with the purpose of improving the tribological properties. Novel nanohybrids of zinc oxide and modified zinc oxide were obtained. The mechanical, thermal and tribological properties were studied. The results of experiments clearly demonstrated that the use of ILs modifies the shape and size of the ZnO nanoparticles, increasing the tribological properties of the novel nanohybrids. Different techniques such as EDS, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectrometry (XPS) were used to examine and establish the surface interactions and mechanism that operated between ILs and ZnO. In summary, the results reveal the importance of the processing parameters on the stability of the nature of the anion in the ILs.

  12. Processing-microstructure models for short- and long-fiber thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Phelps, Jay H.

    The research for this thesis has explored the important microstructural variables for injection-molded thermoplastic composites with discontinuous fiber reinforcement. Two variables, the distributions of fiber orientation and fiber length after processing, have proven to be not only important for correct material property prediction but also difficult to predict using currently available modeling and simulation techniques. In this work, we develop new models for the prediction of these two microstructural variables. Previously, the Folgar-Tucker model has been widely used to predict fiber orientation in injection molded SFT composites. This model accounts for the effects of both hydrodynamics and fiber-fiber interactions in order to give a prediction for a tensorial measure of fiber orientation. However, when applied to at least some classes of LFTs, this model does not match all components of experimental fiber orientation tensor data. In order to address this shortcoming of the model, we hypothesize that Folgar and Tucker's phenomenological treatment of the effects of fiber-fiber interactions with an isotropic rotary diffusion contribution to the rate of change of orientation is insufficient for materials with longer fibers. Instead, this work develops a fiber orientation model that incorporates anisotropic rotary diffusion (ARD). From kinetic theory we derive a general family of evolution equations for the second-order orientation tensor, correcting errors in earlier treatments, and identify a specific equation that is useful for predicting orientation in LFTs. The amount of diffusivity in this model used to approximate the effect of fiber-fiber interactions in each direction is assumed to depend on a second-order space tensor, which is taken to be a function of the orientation state and the rate of deformation. Also, concentrated fiber suspensions align more slowly with respect to strain than the Folgar-Tucker model predicts. Here, we borrow the technique of Wang et al. (2008) to incorporate this behavior in an objective fashion in this new model. Model parameters are selected by matching the experimental steady-state orientation in simple shear flow, and by requiring stable steady states and physically realizable solutions. Utilizing two separate techniques, we identify model parameters for three different materials. We then show that once a set of parameters that meets all previously established criteria has been identified, the differences in model behavior are negligible within that set of parameters. The final model with the proper parameter set is suitable for use in mold filling and other flow simulations, and does give improved predictions of fiber orientation for injection molded LFTs. Although significant fiber length degradation in LFTs has been observed both in literature and in this work, there are no quantitative fiber breakage models to predict either fiber length distributions or average fiber length measures. This work reviews the suspected causes of fiber breakage during the processing of discontinuously-reinforced thermoplastics, specifically LFTs, and introduces a phenomenological fiber breakage model based on the buckling force in a hydrodynamically loaded fiber. This breakage model is incorporated into a conservation equation for total fiber length, and a phenomenological model for the evolution of the fiber length distribution is developed. From this model, we also develop separate, approximate models for the evolution of both the number-average and weight-average fiber length measures. By applying these models to both a simple numerical example and a more complex mold-filling simulation, a qualitative agreement between experiment and prediction is observed. Although these results are promising, the breakage models have only been applied to the mold cavity in injection molding simulation. Both a literature review and our experimental data strongly suggest that the majority of fiber length degradation occurs in the earlier stages of injection molding, in the screw nozzle, runners, and gate. A be

  13. Influence of Structuring by Laser and Plasma Torch on the Adhesion of Metallic Films on Thermoplastic Substrates

    NASA Astrophysics Data System (ADS)

    Knapp, W.; Djomani, D.; Coulon, J. F.; Grunchec, R.

    In this study three different types of thermoplastics haven been investigated: polypropylene (PP, used in automotive industry), poly-ether-ether-ketone (PEEK, used in aerospace applications) and polyethylene (PE, used in medical applications). Surface preparation prior to thin film coating was realized using industrial plasma torch and ultra-short pulse laser. Whereas the plasma torch is a very cost efficient tool the laser light allows precise and localized surface modification. The adhesion measurements of an Al-film deposited on the substrate show that laser structuring can yield in a cohesive rupture. Adhesion can be increased by a factor of 4 to 7 with regard to conventional joining techniques.

  14. Application of Image And X-Ray Microtomography Technique To Quantify Filler Distribution In Thermoplastic-Natural Rubber Blend Composites

    SciTech Connect

    Ahmad, Sahrim; Rasid, Rozaidi; Mouad, A. T. [Faculty of Applied Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bandar Baru Bangi, 43000 Kajang (Malaysia); Aziz Mohamed, A.; Abdullah, Jaafar; Dahlan, M.; Mohamad, Mahathir; Jamro, Rafhayudi; Hamzah Harun, M. [Malaysian Nuclear Agency, Bangi, 43000 Kajang (Malaysia); Yazid, Hafizal [Faculty of Applied Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bandar Baru Bangi, 43000 Kajang (Malaysia); Hafizal Yazid, Faculty of Applied Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bandar Baru Bangi, 43000 Kajang (Malaysia); Abdullah, W. Saffiey W.

    2010-01-05

    X-ray microtomography and ImageJ 1.39 u is used as a tool to quantify volume percentage of B{sub 4}C as fillers in thermoplastic-natural rubber blend composites. The use of percentage of area occupied by fillers as obtain from ImageJ from the microtomography sliced images enables the proposed technique to easily obtain the amount volume percentage of B{sub 4}C in the composite non-destructively. Comparison with other technique such as density measurement and chemical analysis proves the proposed technique as one of the promising approach.

  15. Elastic mesh with thermoplastic polyurethane filaments preserves effective porosity of textile implants.

    PubMed

    Lambertz, Andreas; Vogels, Ruben R M; Binnebösel, Marcel; Schöb, Dominik S; Kossel, Klas; Klinge, Uwe; Neumann, Ulf P; Klink, Christian D

    2015-08-01

    In hernia surgery, meshes with small pores tend to be filled by fibrous tissue, which reduces their stretchability and causes patient complaints. Because of the inelasticity of current meshes, mechanical strain might cause pores to collapse even in large-pore mesh constructions. In this study, a mesh with elastic thermoplastic polyurethane (TPU) filaments was constructed to prevent pore size changes even under mechanical strain, and its biocompatibility in comparison with polyvinylidene fluoride (PVDF) was evaluated. A mesh was constructed using PVDF with elastic TPU filaments and mechanically tested. After midline laparotomy in 20 rabbits, we placed a 15 cm × 3 cm mesh as inlay in the defect. Animals were randomized to either the TPU or PVDF group. After 7 or 21 days, mesh expansion was measured under pneumoperitoneum, and abdominal walls were explanted for immunohistochemical investigations. In vitro, TPU meshes showed a slight reduction in effective porosity from 46% at tension-free conditions to 26% under longitudinal and to 34% under transverse strain. The nonelastic PVDF meshes showed a marked reduction in effective porosity from 70% to 7% and 52%, respectively. The TPU mesh had a breaking elongation of 101% and a tensile strength of 35 N/cm. In vivo, both meshes achieved healing of the incision without hernial defect. The TPU mesh maintained its elasticity under pneumoperitoneum. The amount of CD68-positive, Ki67-positive, and apoptotic cells was significantly lower in the TPU group after 7 and 21 days. The newly developed TPU mesh shows elasticity, structural stability, and preserved effective porosity under mechanical strain. Immunohistochemistry indicates superior biocompatibility of TPU mesh compared with PVDF after 7 and 21 days. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2654-2660, 2015. PMID:25630828

  16. Effect of carbon black and/or elastomer on thermoplastic elastomer-based blends and composites

    NASA Astrophysics Data System (ADS)

    Yasar, M.; Bayram, G.; Celebi, H.

    2015-05-01

    It was aimed to investigate the effect of carbon black and/or elastomer on the electrical conductivity and mechanical properties of thermoplastic elastomer (TPE). Carbon black (CB) and ethylene-glycidyl methacrylate (E-GMA) were used as additives in the main matrix. The blends and composites were characterized in terms of their electrical conductivity and mechanical properties. CB concentration was varied as 0.5, 1, 3 and 5 wt.%. In order to modify the surface of CB, paraffinic oil and silane coupling agents were used. E-GMA was added to the matrix at 5, 10, 20, and 30 wt.% concentration. In order to prepare ternary composites, 5 wt.% of modified or unmodified carbon black and 10 wt.% of E-GMA were mixed with the TPE matrix. The tensile strength, impact strength and elongation at break values of TPE/CB composites decreased while elastic moduli and electrical conductivities increased with increasing CB concentration. It was observed that the surface modification of CB did not alter the tensile properties significantly. However, impact strength of the composites improved upon modification. For TPE/E-GMA blends, E-GMA addition enhanced the tensile strength and impact strength values of neat TPE. Nevertheless, elongation at break values began to decrease at 10 wt% and higher concentrations of E-GMA. It was observed that CB was more effective than the E-GMA on the mechanical properties of the ternary composites. The addition of 10 wt.% E-GMA increased the electrical resistivity and impact strength values of the ternary composites, as expected.

  17. Tuning micropillar tapering for optimal friction performance of thermoplastic gecko-inspired adhesive.

    PubMed

    Kim, Yongkwan; Chung, Yunsie; Tsao, Angela; Maboudian, Roya

    2014-05-14

    We present a fabrication method and friction testing of a gecko-inspired thermoplastic micropillar array with control over the tapering angle of the pillar sidewall. A combination of deep reactive ion etching of vertical silicon pillars and subsequent maskless chemical etching produces templates with various widths and degrees of taper, which are then replicated with low-density polyethylene. As the silicon pillars on the template are chemically etched in a bath consisting of hydrofluoric acid, nitric acid, and acetic acid (HNA), the pillars are progressively thinned, then shortened. The replicated polyethylene pillar arrays exhibit a corresponding increase in friction as the stiffness is reduced with thinning and then a decrease in friction as the stiffness is again increased. The dilution of the HNA bath in water influences the tapering angle of the silicon pillars. The friction of the replicated pillars is maximized for the taper angle that maximizes the contact area at the tip which in turn is influenced by the stiffness of the tapered pillars. To provide insights on how changes in microscale geometry and contact behavior may affect friction of the pillar array, the pillars are imaged by scanning electron microscopy after friction testing, and the observed deformation behavior from shearing is related to the magnitude of the macroscale friction values. It is shown that the tapering angle critically changes the pillar compliance and the available contact area. Simple finite element modeling calculations are performed to support that the observed deformation is consistent with what is expected from a mechanical analysis. We conclude that friction can be maximized via proper pillar tapering with low stiffness that still maintains enough contact area to ensure high adhesion. PMID:24761942

  18. Automatic building of a web-like structure based on thermoplastic adhesive.

    PubMed

    Leach, Derek; Wang, Liyu; Reusser, Dorothea; Iida, Fumiya

    2014-09-01

    Animals build structures to extend their control over certain aspects of the environment; e.g., orb-weaver spiders build webs to capture prey, etc. Inspired by this behaviour of animals, we attempt to develop robotics technology that allows a robot to automatically builds structures to help it accomplish certain tasks. In this paper we show automatic building of a web-like structure with a robot arm based on thermoplastic adhesive (TPA) material. The material properties of TPA, such as elasticity, adhesiveness, and low melting temperature, make it possible for a robot to form threads across an open space by an extrusion-drawing process and then combine several of these threads into a web-like structure. The problems addressed here are discovering which parameters determine the thickness of a thread and determining how web-like structures may be used for certain tasks. We first present a model for the extrusion and the drawing of TPA threads which also includes the temperature-dependent material properties. The model verification result shows that the increasing relative surface area of the TPA thread as it is drawn thinner increases the heat loss of the thread, and that by controlling how quickly the thread is drawn, a range of diameters can be achieved from 0.2-0.75 mm. We then present a method based on a generalized nonlinear finite element truss model. The model was validated and could predict the deformation of various web-like structures when payloads are added. At the end, we demonstrate automatic building of a web-like structure for payload bearing. PMID:24960453

  19. Novel starch thermoplastic/Bioglass composites: mechanical properties, degradation behavior and in-vitro bioactivity.

    PubMed

    Leonor, I B; Sousa, R A; Cunha, A M; Reis, R L; Zhong, Z P; Greenspan, D

    2002-10-01

    The present research aims to evaluate the possibility of creating new degradable, stiff and highly bioactive composites based on a biodegradable thermoplastic starch-based polymeric blend and a Bioglass filler. Such combination should allow for the development of bioactive and degradable composites with a great potential for a range of temporary applications. A blend of starch with ethylene-vinyl alcohol copolymer (SEVA-C) was reinforced with a 45S5 Bioglass powder presenting a granulometric distribution between 38 and 53 microm. Composites with 10 and 40 wt % of 45S5 Bioglass were compounded by twin-screw extrusion (TSE) and subsequently injection molded under optimized conditions. The mechanical properties of the composites were evaluated by tensile testing, and their bioactivity assessed by immersion in a simulated body fluid (SBF) for different periods of time. The biodegradability of these composites was also monitored after several immersion periods in an isotonic saline solution. The tensile tests results obtained indicated that SEVA-C/Bioglass composites present a slightly higher stiffness and strength (a modulus of 3.8 GPa and UTS of 38.6 MPa) than previously developed SEVA-C/Hydroxylapatite (HA) composites. The bioactivity of SEVA-C composites becomes relevant for 45S5 amounts of only 10 wt %. This was observed by scanning electron microscopy (SEM) and confirmed for immersion periods up to 30 days by both thin-film X-ray diffraction (TF-XRD) (where HA typical peaks are clearly observed) and induced coupled plasma emission (ICP) spectroscopy used to follow the elemental composition of the SBF as function of time. Additionally, it was observed that the composites are biodegradable being the results correlated with the correspondent materials composition. PMID:15348187

  20. Radiation processing of thermoplastic starch by blending aromatic additives: Effect of blend composition and radiation parameters

    NASA Astrophysics Data System (ADS)

    Khandal, Dhriti; Mikus, Pierre-Yves; Dole, Patrice; Coqueret, Xavier

    2013-03-01

    This paper reports on the effects of electron beam (EB) irradiation on poly ?-1,4-glucose oligomers (maltodextrins) in the presence of water and of various aromatic additives, as model blends for gaining a better understanding at a molecular level the modifications occurring in amorphous starch-lignin blends submitted to ionizing irradiation for improving the properties of this type of bio-based thermoplastic material. A series of aromatic compounds, namely p-methoxy benzyl alcohol, benzene dimethanol, cinnamyl alcohol and some related carboxylic acids namely cinnamic acid, coumaric acid, and ferulic acid, was thus studied for assessing the ability of each additive to counteract chain scission of the polysaccharide and induce interchain covalent linkages. Gel formation in EB-irradiated blends comprising of maltodextrin was shown to be dependent on three main factors: the type of aromatic additive, presence of glycerol, and irradiation dose. The chain scission versus grafting phenomenon as a function of blend composition and dose were studied using Size Exclusion Chromatography by determining the changes in molecular weight distribution (MWD) from Refractive Index (RI) chromatograms and the presence of aromatic grafts onto the maltodextrin chains from UV chromatograms. The occurrence of crosslinking was quantified by gel fraction measurements allowing for ranking the cross-linking efficiency of the additives. When applying the method to destructurized starch blends, gel formation was also shown to be strongly affected by the moisture content of the sample submitted to irradiation. The results demonstrate the possibility to tune the reactivity of tailored blend for minimizing chain degradation and control the degree of cross-linking.