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1

Thermoplastic dry polymer powder prepregging  

SciTech Connect

Thermoplastic resin systems have shown potential for reducing the manufacturing costs and improving the damage tolerance of composite structures. Current methods for thermoplastic resin impregnation of fiber bundles are limited by various difficulties and thus produce poor quality prepregs. The emerging technology of fiber is one of the most promising options, producing excellent matrix drape, and feasibility for a wide variety of matrix systems. An electrostatic dry polymer powder prepregging system was developed at the NSF Science and Technology Center at Virginia Tech, and has been used to produce high quality thermoplastic towpreg from a wide variety o polymer matrices. Additionally, a modification of the system allows for the production of towpreg from 15 gram polymer samples. This is ideal for the production of composites from resin systems under development, allowing early feedback concerning processing and composite mechanical performance.

Bucher, R.A.; Loos, A.C.; Meyer, G. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)] [and others

1995-12-01

2

Diamond turning of thermoplastic polymers  

SciTech Connect

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.

Smith, E.; Scattergood, R.O.

1988-12-01

3

Bonding of thermoplastic polymer microfluidics  

Microsoft Academic Search

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

Chia-Wen Tsao; Don L. DeVoe

2009-01-01

4

Predicting Wear From Mechanical Properties of Thermoplastic Polymers  

E-print Network

Predicting Wear From Mechanical Properties of Thermoplastic Polymers Witold Brostow,1,2 Haley E at break and storage modulus for thermoplastic polymers. We provide a formula connecting brittleness to visco- elastic recovery (healing) after sliding wear. Our model fits a selection of ten thermoplastics

North Texas, University of

5

Thermoplastic polymers for improved fire safety  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

6

Microscale patterning of thermoplastic polymer surfaces by selective solvent swelling.  

PubMed

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

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

2012-09-01

7

Novel polymer blends with thermoplastic starch  

NASA Astrophysics Data System (ADS)

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

Taghizadeh, Ata

8

High temperature drilling fluids based on sulfonated thermoplastic polymers  

SciTech Connect

An oil-based drilling mud is described which consists of: (a) a hydrocarbon oil; (b) about 1 to about 10 parts by weight of water per 100 parts by weight of the hydrocarbon oil; (c) about 20 to about 50 lb/bbl of at least one emulsifier; (d) weighting material necessary to achieve the desired density; and (e) about 0.25 to about 4.0 lb/bbl of a water insoluble and oil insoluble neutralized sulfonated thermoplastic polymer having a molecular weight as measured by GPC of about 5,000 to about 500,000, the water insoluble and oil insoluble neutralized sulfonated thermoplastic polymer having about 5 to about 100 meq. of sulfonate groups per 100 grams of the neutralized sulfonated thermoplastic polymer. The water insoluble and oil insoluble sulfonated thermoplastic is derived from a polymer selected from the group consisting of polystyrene, poly-t-butyl-styrene, polychlorostyrene, poly-alpha methyl styrene, polyvinyl toluene and co- or terpolymers of styrene and acrylonitrile, methyl methacrylate and butadiene.

Walker, T.O.; Peiffer, D.G.; Lundberg, R.D.

1986-04-01

9

Effects of Surface Plasma Treatment on Tribology of Thermoplastic Polymers  

E-print Network

Effects of Surface Plasma Treatment on Tribology of Thermoplastic Polymers Alexander Bismarck,1) to atmospheric pressure oxygen plasma treatment for varying amounts of time. Effects of the treatment have been and increase of hydrophilicity. Based on the effects of oxygen plasma treatment on PC and LDPE, these two

North Texas, University of

10

Planar 77 GHz antennas on new thermoplastic polymer substrate  

Microsoft Academic Search

In this paper, we describe the design and layout of planar patch antenna arrays for automotive radar applications at 77 GHz. Based on the low loss thermoplastic polymer substrate material ER182, single layer arrays with high directivity and efficiency of up to 78% are fabricated. Hybrid series\\/corporate feed networks are designed and beamforming capabilities in the E-plane as well as

Martin Schneider; Marius D. Richter

2010-01-01

11

Magnetron sputtered titanium nitride thin films on thermoplastic polymers  

Microsoft Academic Search

Enhancing the durability of thermoplastic polymers is desirable for improved wear resistance (rubbing, scratching, impact) of plastics in particle sensitive environments. In this investigation poly(butylene terephthalate) (PBT), poly(amide)6.6 (PA) and poly(carbonate) (PC) were chosen as substrate material. The selected coating material was titanium nitride (Ti–N), which is known as wear resistant coating in various applications like drilling and for other

E. Lugscheider; S. Bärwulf; M. Riester; H. Hilgers

1999-01-01

12

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

E-print Network

REVIEW Bonding of thermoplastic polymer microfluidics Chia-Wen Tsao Ã? Don L. DeVoe Received: 20 Abstract Thermoplastics are highly attractive substrate materials for microfluidic systems, with important range of thermoplastics, sealing of these components is required for the formation of enclosed

Rubloff, Gary W.

13

Lactic acid polymers: strong, degradable thermoplastics  

SciTech Connect

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

Wehrenberg, R.H.

1981-01-01

14

Process for preparing tapes from thermoplastic polymers and carbon fibers  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

15

Damage healing ability of a shape-memory-polymer-based particulate composite with small thermoplastic contents  

NASA Astrophysics Data System (ADS)

The purpose of this study is to investigate the potential of a shape-memory-polymer (SMP)-based particulate composite to heal structural-length scale damage with small thermoplastic additive contents through a close-then-heal (CTH) self-healing scheme that was introduced in a previous study (Li and Uppu 2010 Comput. Sci. Technol. 70 1419-27). The idea is to achieve reasonable healing efficiencies with minimal sacrifice in structural load capacity. By first closing cracks, the gap between two crack surfaces is narrowed and a lesser amount of thermoplastic particles is required to achieve healing. The particulate composite was fabricated by dispersing copolyester thermoplastic particles in a shape memory polymer matrix. It is found that, for small thermoplastic contents of less than 10%, the CTH scheme followed in this study heals structural-length scale damage in the SMP particulate composite to a meaningful extent and with less sacrifice of structural capacity.

Nji, Jones; Li, Guoqiang

2012-02-01

16

Analysis of thermoplastic polyimide + polymer liquid crystal blends  

NASA Astrophysics Data System (ADS)

Thermoplastic polyimides (TPIs) exhibit high glass transition temperatures (Tsbgs), which make them useful in high performance applications. Amorphous and semicrystalline TPIs show sub-Tsbg relaxations, which can aid in improving strength characteristics through energy absorption. The alpha relaxation of both types of TPIs indicates a cooperative nature. The semicrystalline TPI shows thermo-irreversible cold crystallization phenomenon. The polymer liquid crystal (PLC) used in the blends is thermotropic and with longitudinal molecular structure. The small heat capacity change (Delta Csb{p}) associated with the glass transition indicates the PLC to be rigid rod in nature. The PLC shows a small endotherm associated with the melting. The addition of PLC to the semicrystalline TPI does not significantly affect the Tsbg or the melting point (Tsbm). The cold crystallization temperature (Tsbc) increases with the addition of the PLC, indicating channeling phenomenon. The addition of PLC also causes a negative deviation of the Delta Csb{p}, which is another evidence for channeling. The TPI, PLC and their blends show high thermal stability. The semicrystalline TPI absorbs moisture; this effect decreases with the addition of the PLC. The absorbed moisture does not show any effect on the degradation. The addition of PLC beyond 30 wt.% does not result in an improvement of properties. The amorphous TPI + PLC blends also show the negative deviation of Delta Csb{p} from linearity with composition. The addition of PLC causes a decrease in the thermal conductivity in the transverse direction to the PLC orientation. The thermomechanical analysis indicates isotropic expansivity for the amorphous TPI and a small anisotropy for the semicrystalline TPI. The PLC shows large anisotropy in expansivity. Even 5 wt.% concentration of PLC in the blend induces considerable anisotropy in the expansivity. Thus, blends show controllable expansivity through PLC concentration. Amorphous TPI + PLC blends also show excellent film formability. The amorphous TPI blends show good potential for applications requiring high thermal stability, controlled expansivity and good film formability.

Gopalanarayanan, Bhaskar

17

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

18

Friction and wear performance of some thermoplastic polymers and polymer composites against unsaturated polyester  

NASA Astrophysics Data System (ADS)

Wear experiments have been carried out with a range of unfilled and filled engineering thermoplastic polymers sliding against a 15% glass fibre reinforced unsaturated polyester polymer under 20, 40 and 60 N loads and 0.5 m/s sliding speed. Pin materials used in this experimental investigation are polyamide 66 (PA 66), poly-ether-ether-ketone (PEEK) and aliphatic polyketone (APK), glass fibre reinforced polyamide 46 (PA 46 + 30% GFR), glass fibre reinforced polytetrafluoroethylene (PTFE + 17% GFR), glass fibre reinforced poly-ether-ether-ketone (PEEK + 20% GFR), glass fibre reinforced poly-phylene-sulfide (PPS + 30% GFR), polytetrafluoroethylene filled polyamide 66 (PA 66 + 10% PTFE) and bronze filled pofytetrafluoroethylene (PTFE + 25% bronze) engineering polymers. The disc material is a 15% glass fibre reinforced unsaturated polyester thermoset polymer produced by Bulk Moulding Compound (BMC). Sliding wear tests were carried out on a pin-on-disc apparatus under 0.5 m/s sliding speed and load values of 20, 40 and 60 N. The results showed that the highest specific wear rate is for PPS + 30% GFR with a value of 1 × 10 -11 m 2/N and the lowest wear rate is for PTFE + 17% GFR with a value of 9.41 × 10 -15 m 2/N. For the materials and test conditions of this investigation, apart from polyamide 66 and PA 46 + 30% GFR polymers, the coefficient of friction and specific wear rates are not significantly affected by the change in load value. For polyamide 66 and PA 46 + 30% GFR polymers the coefficient of friction and specific wear rates vary linearly with the variation in load values.

Unal, H.; Mimaroglu, A.; Arda, T.

2006-09-01

19

Noncontact Microembossing Technology for Fabricating Thermoplastic Optical Polymer Microlens Array Sheets  

PubMed Central

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

Chang, Xuefeng; Ge, Xiaohong; Li, Hui

2014-01-01

20

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

NASA Astrophysics Data System (ADS)

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.

Ganesan, Amirthan; Yamada, Motohiro; Fukumoto, Masahiro

2013-12-01

21

Thermodynamics of water sorption in high performance glassy thermoplastic polymers  

PubMed Central

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

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

2014-01-01

22

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

PubMed

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

Schulz, Ulrike

2006-03-01

23

Review of modern techniques to generate antireflective properties on thermoplastic polymers  

NASA Astrophysics Data System (ADS)

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

Schulz, Ulrike

2006-03-01

24

Photocleavable junctions in complex polymer architectures and photoetchable thermoplastics  

NASA Astrophysics Data System (ADS)

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

Sterner, Elizabeth Surles

25

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

PubMed

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

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

2013-07-16

26

IR laser radiation induced changes in the IR absorption spectra of thermoplastic and thermosetting polymers  

NASA Astrophysics Data System (ADS)

This paper demonstrates that powerful laser radiation causes changes in the absorbance spectra of epoxy resin, polyethylene and polysulfone. Thin polymer films were located between IR AgBrCl optical fibres and exposed to the radiation of a CO2 laser. The output of the laser source was varied in the range 0-8.5 W. The absorbance spectra were recorded using a Fourier transform infrared (FTIR) spectrophotometer. It was revealed that characteristic polymer absorbance peaks decay under exposure to the powerful IR light. The apparent dependence of peak magnitude on IR radiation power has been established. We showed that the phenomenon of the absorbance peak disappearances associated with the polymers - thermoplastic (including an engineering polymer such as polysulfone) and thermosetting - is of a threshold nature. The mathematical theory of the observed effect was derived. We propose that the effect under discussion is caused by the oxygen-free thermal action of IR radiation on the chemical structure of the polymer materials. The revealed effect could be effectively used to lower the losses in adhesive contacts of IR optical elements. The novelty of the proposed method lies in the fact that thermal treatment is localized strictly within the adhesive layer; optical elements to be contacted (fibres, lenses, etc) which are highly IR transparent do not experience the IR radiation, but the polymer adhesive is subjected to a temperature rise.

Bormashenko, Edward; Pogreb, Roman; Sheshnev, Avigdor; Shulzinger, Eugene; Bormashenko, Yelena; Katzir, Abraham

2001-07-01

27

Effects of thermal modification on the adhesion between spruce wood ( Picea abies Karst. ) and a thermoplastic polymer  

Microsoft Academic Search

In order to study the effect of thermal treatment on the adhesion between wood and a nonpolar thermoplastic polymer, spruce wood boards (Picea abies Karst.) were heat-treated and bonded with polyethylene. As a result the contact angle of an applied water droplet increased significantly. A strong improvement of the adhesion between the modified wood surface and polyethylene was found by

J. Follrich; U. Müller; W. Gindl

2006-01-01

28

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

PubMed Central

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

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

2013-01-01

29

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

PubMed Central

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

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

2012-01-01

30

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

31

In Situ Reinforcing Elastomer Composite Based on Polyolefinic Thermoplastic Elastomer and Thermotropic Liquid Crystalline Polymer  

NASA Astrophysics Data System (ADS)

In situ reinforcing elastomer composites based on Santoprene thermoplastic elastomer, a polymerized polyolefin compound of ethylene-propylene-diene monomer (EPDM)/polypropylene (PP), and a thermotropic liquid crystalline polymer (TLCP), Rodrun LC3000, were prepared using a single-screw extruder. The rheological behavior, morphology, mechanical and thermal properties of the blends containing various LC3000 contents were investigated. All neat components and their blends exhibited shear thinning behavior. With increasing TLCP content, processability became easier because of the decrease in melt viscosity of the blends. Despite the viscosity ratio of dispersed phase to the matrix phase for the blend system is lower than 0.14, most of TLCP domains in the blends containing 5-10 wt% LC3000 appeared as droplets. At 20 wt% LC3000 or more, the domain size of TLCP became larger due to the coalescence of liquid TLCP threads that occurred during extrusion. The addition of LC3000 into the elastomer matrix enhanced the initial tensile modulus considerably whereas the extensibility of the blends remarkably decreased with addition of high TLCP level (>20wt%). The results obtained from thermogravimetric analysis suggested that the incorporation of LC3000 into Santoprene slightly improved the thermal resistance both in nitrogen and in air.

Saikrasun, Sunan; Phoban, Yuwararat; Limpisawasdi, Panpirada; Amornsakchai, Taweechai

32

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

Microsoft Academic Search

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

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

2000-01-01

33

Thermoplastics Properties J. D. Muzzy  

E-print Network

2.3 Thermoplastics ­ Properties J. D. Muzzy Georgia Institute of Technology, Atlanta, GA, USA 2.3.4 THERMOPLASTIC GROUPS 2.3.4.1.1 Polyolefins 2.3.4.1.2 Styrenics 2.3.4.1.3 Vinyls 2.3.4.1.9 Polyethers 2.3.4.1.10 Sulfur Containing polymers 2.3.4.1.11 Additional Thermoplastics 2.3.5 ACKNOWLEDGEMENTS

Colton, Jonathan S.

34

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

E-print Network

in thermoplastics and epoxy cure A. Demcenko a, , V. Koissin a , V.A. Korneev b a Faculty of Engineering Technology has shown effective monitoring and scanning capabil- ities when applied to thermoplastic ageing, epoxy of the physical ageing of thermoplastics [1,4,5] and epoxy curing, e.g. [6­8], is higher when a nonlinear wave

Korneev, Valeri A.

35

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

E-print Network

, and Potential as Thermoplastic Elastomer Yi Yi, Xinghe Fan, Xinhua Wan, Lei Li, Ning Zhao, Xiaofang Chen, Jian as liquid crystalline thermoplastic elastomer (LCTPE). The synthetic strategy is to obtain a difunctional and tensile tests prove that the sample has the potential as thermoplastic elastomers (TPEs). According to our

Wan, Xin-hua

36

Review of modern techniques to generate antireflective properties on thermoplastic polymers  

Microsoft Academic Search

Modern optical applications need solutions for providing polymer surfaces with antireflective properties. The problems involved in coating comprise thermal limitations, incompatible mechanical properties of coating and substrate materials, and interaction between polymers and plasma. As an alternative for coating, antireflective properties on polymers can also be obtained by hot embossing or by ion etching of surface structures. My objective is

Ulrike Schulz

2006-01-01

37

In situ ceramic fillers of electrospun thermoplastic polyurethane\\/poly(vinylidene fluoride) based gel polymer electrolytes for Li-ion batteries  

Microsoft Academic Search

Gel polymer electrolyte films based on thermoplastic polyurethane (TPU)\\/poly(vinylidene fluoride) (PVdF) with and without in situ ceramic fillers (SiO2 and TiO2) are prepared by electrospinning 9wt% polymer solution at room temperature. The electrospun TPU–PVdF blending membrane with 3% in situ TiO2 shows a highest ionic conductivity of 4.8×10?3Scm?1 with electrochemical stability up to 5.4V versus Li+\\/Li at room temperature and

Na Wu; Qi Cao; Xianyou Wang; Sheng Li; Xiaoyun Li; Huayang Deng

2011-01-01

38

Preparation of Thermoplastic X-ray Masks for Medical Applications  

Microsoft Academic Search

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

Jindarat Pimsamarn

39

IR laser radiation induced changes in the IR absorption spectra of thermoplastic and thermosetting polymers  

Microsoft Academic Search

This paper demonstrates that powerful laser radiation causes changes in the absorbance spectra of epoxy resin, polyethylene and polysulfone. Thin polymer films were located between IR AgBrCl optical fibres and exposed to the radiation of a CO2 laser. The output of the laser source was varied in the range 0-8.5 W. The absorbance spectra were recorded using a Fourier transform

Edward Bormashenko; Roman Pogreb; Avigdor Sheshnev; Eugene Shulzinger; Yelena Bormashenko; Abraham Katzir

2001-01-01

40

The effect of gamma-radiation on polymer composites based on thermoplastic matrices  

Microsoft Academic Search

The effect of 60Co ?-radiation on polymer composite materials (PCMs) based on reinforcing glass cloth, polyethylene (PE), polyamide (PA) and\\u000a polypropylene (PP) matrices has been studied. It has been found that PCMs based on more durable PP and PA matrices have a\\u000a substantially lower radiation resistance as compared to their PE-matrix analogs. More stable carbon-reinforced plastics based\\u000a on the PE

Yu. N. Smirnov; S. R. Allayarov; V. A. Lesnichaya; Yu. A. Ol’khov; G. P. Belov; D. A. Dixon

2009-01-01

41

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

NASA Astrophysics Data System (ADS)

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

Frick, Achim; Rochman, Arif; Martin, Peter

2011-05-01

42

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

E-print Network

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. ...

Ibrahim, Sarah H

2005-01-01

43

Processable Aromatic Polyimide Thermoplastic Blends  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

44

A thermoplastic polyimidesulfone  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

46

Highlights in these programmes are: i vacuum consolidation of thermoplastic  

E-print Network

Highlights in these programmes are: i vacuum consolidation of thermoplastic fibre composites thermoplastic polymer matrix composites (PMCs) and associated process technologies. The aim is to improve of thermoplastic poly- mers can be as high as several thousand Pa s, which means that it is difficult

47

Thermoplastic Coated Carbon Fibers for Textile Preforms  

Microsoft Academic Search

A continuous process for producing prepreg from carbon fiber and thermoplastic matrix is described. After the tow has been spread using a pneumatic device, the process utilizes a fluidized bed to apply thermoplastic powder to the bun dle. Finally, direct electrical heating of the coated fiber tow melts the polymer on the individual fibers, creating a uniform and extremely flexible

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

1989-01-01

48

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 of disposable, point-of-care microfluidic chips. The most promising class of materials is thermoplastic polymers

49

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

PubMed

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

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

2014-02-01

50

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

PubMed

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. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1434-1444, 2014. PMID:24574168

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

2014-10-01

51

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

52

Aerogel/polymer composite materials  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

53

Macromol. Rapid Commun. 19, 557561 (1998) 557 X-ray microscopy of novel thermoplastic/liquid crystalline  

E-print Network

Macromol. Rapid Commun. 19, 557­561 (1998) 557 X-ray microscopy of novel thermoplastic-cost polymeric blends. Blends of a thermoplastic polymer and a nematic LCP are produced here by mechanical), LCPs are expected to improve the mechanical properties of thermoplastic polymers by serving

54

Thermally modulated nanostructure of poly(-caprolactone)ePOSS multiblock thermoplastic polyurethanes  

E-print Network

Thermally modulated nanostructure of poly(-caprolactone)ePOSS multiblock thermoplastic Accepted 8 April 2013 Available online 15 April 2013 Keywords: POSS Thermoplastic polyurethane Competitive of applications such as thermoplastic elastomers [3], stimuli-responsive shape memory polymers [4e7], information

Mather, Patrick T.

55

Thermoplastic Resin Sales by Major Market (millions of pounds, dry weight basis)  

E-print Network

Thermoplastic Resin Sales by Major Market 2004-2008 (millions of pounds, dry weight basis) Major selected thermoplastic resins: Low-Density Polyethylene Polyvinyl Chloride Linear-Low-Density Polyethylene-Acrylonitrile Polystyrene Other Styrene-based Polymers Styrene Butadiene Latexes (SBL) Engineering Resins Thermoplastic

Laughlin, Robert B.

56

Textile impregnation with thermoplastic resin - models and application  

Microsoft Academic Search

One of the key issues of the development of cost-effective thermoplastic composites for the aerospace industry is the process quality control. A complete, void free impregnation of the textile reinforcement by the thermoplastic resin is an important measure of the quality of composites. The introduction of new, more thermal resistant and tougher polymers is accompanied by a large number of

R. Loendersloot; W. J. B. Grouve; E. A. D. Lamers; S. Wijskamp; P. A. Kelly; S. Bickerton; P. Lescher; Q. Govignon

2012-01-01

57

Ribbonizing of electrostatic powder spray impregnated thermoplastic tows by pultrusion  

Microsoft Academic Search

Process models have been developed for thermoset pultrusion and thermoplastic pultrusion using melt impregnated prepregs. Thermoplastic towpregs are manufactured using new innovative methods such as those using dry powder impregnation. The morphology of dry powder impregnated ‘towpregs’ consists of a dry fibre bundle surrounded by a layer of polymer. In this study a two-dimensional finite element model using non-Newtonian fluid

Narasinha C. Parasnis; Karthik Ramani; Harshad M. Borgaonkar

1996-01-01

58

Thermoplastic-carbon fiber hybrid yarn  

NASA Technical Reports Server (NTRS)

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

Ketterer, M. E.

1984-01-01

59

An overview of long fiber reinforced thermoplastics  

SciTech Connect

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.

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

1997-12-31

60

Thermophysical, dielectric, and electro-optic properties of nematic liquid crystal droplets confined to a thermoplastic polymer matrix.  

PubMed

The thermophysical, dielectric and electro-optic properties of polymer-dispersed liquid crystal (PDLC) films made of monodisperse polystyrene (PS) and 4-n-pentyl-4(')-cyanobiphenyl (5CB) are investigated by polarized optical microscopy, differential scanning calorimetry, ac impedance analysis, and forward transmittance measurement technique. The PS-5CB system exhibits an upper critical solution temperature (UCST) shape phase diagram with a wide isotropic+isotropic (I+I) miscibility gap between the isotropic and nematic+isotropic (N+I) regions. An absorption domain in the dielectric spectrum of PDLC films was clearly observed at low frequency, and unambiguously assigned to the confined liquid crystalline phase in both nematic and isotropic states. The correlation between the dielectric and electro-optical results for PS-5CB (30:70) samples has shown that in the vicinity of the low frequency absorption domain ( approximately 200 Hz at T=25 degrees C), a drastic decrease in the optical transmittance of the film occurs. This phenomenon can be related to an interfacial polarization process resulting from a charge accumulation at the droplet-polymer interface (Maxwell-Wagner-Sillars effect). PMID:15089305

Boussoualem, Mourad; Roussel, Frédérick; Ismaili, Mimoun

2004-03-01

61

Effect of annealing history on free volume in thermoplastics  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

62

Long carbon fiber thermoplastics for injection molding  

SciTech Connect

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.

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

1993-12-31

63

Polymer International Polym Int 53:16931703 (2004) DOI: 10.1002/pi.1530  

E-print Network

Polymer International Polym Int 53:1693­1703 (2004) DOI: 10.1002/pi.1530 Thermoplastic elastomers and reactive BRs to produce thermoplastic elastomers (TPEs). TPEs were characterized by thermogravimetric; BR; TPE INTRODUCTION It is known that thermoplastic elastomers (TPEs) can be produced from polymer

North Texas, University of

64

Thermoplastic coated carbon fibers for textile preforms  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

65

Thermal monitoring of the thermoplastic injection molding process with FBGs  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

66

Electromagnetic radiation calorimetry of thermoplastics, elastomers, and composite systems  

Microsoft Academic Search

Microwave radiation for processing of glassy and semicrystalline thermoplastics, elastomeric polymers and composites was investigated. The goal was to reveal the relationship between polymer structure and microwave absorptivity, and hence processability. Specimens were subjected to an electric field at 2.45 GHz either inside a rectangular waveguide or in a cylindrical resonant cavity. Applicator with less than 100 watts applied power.

1989-01-01

67

Thermoplastic starch\\/natural rubber blends  

Microsoft Academic Search

Thermoplastic starch\\/natural rubber polymer blends were prepared using directly natural latex and cornstarch. The blends were prepared in an intensive batch mixer at 150°C, with natural rubber content varying from 2.5 to 20%. The blends were characterised by mechanical analysis (stress-strain) and by scanning electron microscopy. The results revealed a reduction in the modulus and in tensile strength, becoming the

A. J. F Carvalho; A. E Job; N Alves; A. A. S Curvelo; A Gandini

2003-01-01

68

Thermochemical and Flammability Properties of Some Thermoplastic and Thermoset Polymersa Review  

Microsoft Academic Search

There is an increasing demand both for thermoplastic and thermoset resins which, depending on the application, must exhibit one or more high performance characteristics. The resin chosen for a particular application must not only meet the end requirements but also must have good processing characteristics. High performance thermoplastic polymers and thermoset resins must possess one or more of the following

Demetrius A. Kourtides

1978-01-01

69

Pen microfluidics: rapid desktop manufacturing of sealed thermoplastic microchannels.  

PubMed

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

Rahmanian, Omid; DeVoe, Don L

2013-03-21

70

Pultrusion process development of a graphite reinforced polyetherimide thermoplastic composite  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

71

Applications of azidosilane coupling agents in reinforced thermoplastic composites  

Microsoft Academic Search

Treatment of mica, glass microspheres, milled glass fibers and commercial chopped fiberglass with azidosilane coupling agents is shown to significantly improve the mechanical properties of these fillers\\/reinforcements in polyolefins relative to untreated controls. The unique chemistry of the azido groups allows for coupling with a wide variety of thermoplastic polymers. Surface characterization of native and modified fillers has proven to

Kolpak

1986-01-01

72

Thermoplastic Composite Wind Turbine Blades: Kinetics and Processability  

Microsoft Academic Search

In previous research, the potential of glass fibre reinforced anionic polyamide-6 (APA-6) composites for use in wind turbine blades was proven. Based on polymer properties, viscosity, processing time, costs and recyclability, APA-6 composites are considered the most suitable reactive thermoplastic material candidate. However, more research is needed to mature the knowledge of the APA-6 material and its processing which can

J. J. E. Teuwen

2011-01-01

73

Imprint of sub-25 nm vias and trenches in polymers Stephen Y. Chou, Peter R. Krauss, and Preston J. Renstrom  

E-print Network

process that presses a mold into a thin thermoplastic polymer film on a substrate to create vias. As shown in Fig. 1, in the nanoimprint process, a mold is pressed into a thin thermoplastic polymer film

74

Introduction Short fibre reinforced thermoplastics are widely  

E-print Network

Introduction Short fibre reinforced thermoplastics are widely used for plastic part production because they can be processed with the same machines as classi- cal thermoplastics, but present enhanced, Injection moulding of fibre reinforced thermoplastics: integration of fibre orientation and mechanical

Paris-Sud XI, Université de

75

Thermoplastic starch composites and blends.  

E-print Network

??The central theme of this thesis was the development of thermoplastic starch materials and composites, their characterization and analysis of mechanical properties. X-ray diffraction methodology… (more)

Frost, K

2010-01-01

76

EthylenePropyleneSilsesquioxane Thermoplastic Elastomers  

E-print Network

Ethylene­Propylene­Silsesquioxane Thermoplastic Elastomers Bradley Seurer, E. Bryan Coughlin nanocrystals increases the mechanical properties of these thermoplastic elastomers. The tensile storage modulus

77

Thermoplastic film prevents proppant flowback  

Microsoft Academic Search

Thermoplastic film added to proppants is effective and economical for preventing proppant flowback after an hydraulic fracturing treatment. Most other methods, such as resin-coated proppant and fiber, for controlling proppant flowback have drawbacks that added to treatment costs by requiring long downtime, costly additives, or frequent equipment replacement. Thermoplastic film does not react chemically with fracturing fluids. After the proppant

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

1996-01-01

78

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

SciTech Connect

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

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

2011-10-01

79

Thermoplastic waves in magnetars  

E-print Network

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.

Beloborodov, Andrei M

2014-01-01

80

Thermoplastic Waves in Magnetars  

NASA Astrophysics Data System (ADS)

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.

Beloborodov, Andrei M.; Levin, Yuri

2014-10-01

81

Thermoplastic Patient Fixation  

Microsoft Academic Search

\\u000a Background and Purpose:  Several methods have been developed to reduce tumor motions and patient movements during radiotherapy of lung cancer. In this\\u000a study, a multislice CT-based analysis was performed to examine the effect of a thermoplastic patient immobilization system\\u000a on the chest wall and tumor motions.\\u000a \\u000a \\u000a \\u000a Patients and Methods:  Ten patients with stage II–IV lung cancer were enrolled into the study. According

Arpad Kovacs; Janaki Hadjiev; Ferenc Lakosi; Marta Vallyon; Zsolt Cselik; Peter Bogner; Akos Horvath; Imre Repa

2007-01-01

82

Graphite fiber reinforced thermoplastic resins  

NASA Technical Reports Server (NTRS)

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.

Novak, R. C.

1975-01-01

83

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

NASA Technical Reports Server (NTRS)

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.

Theil, M. H.

1986-01-01

84

Thermoplastic bonding of microfluidic substrates  

E-print Network

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

Judge, Benjamin Michael

2012-01-01

85

Close Encounters of the Polymer Kind  

NSDL National Science Digital Library

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.

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

86

Mechanical properties of green composites based on thermoplastic starch  

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

87

Millimeter Wave Complex Permittivity Measurements of High Dielectric Strength Thermoplastics  

Microsoft Academic Search

This paper presents for the first time the complex dielectric permittivity and loss tangent measurements for a selection of advanced polymer-based thermoplastics in the Q-band, V-band and W-band frequencies. These plastics are reported to have exceptional mechanical, thermal and electrical properties and are extensively used as electrical insulating materials, often operating at high voltages. With this view in mind, we

Nahid Rahman; Shu Chen; K. A. Korolev; M. N. Afsar; R. Cheung; M. Aghion

2008-01-01

88

Graft polymerization of native chicken feathers for thermoplastic applications.  

PubMed

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

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

2011-03-01

89

Graphite fiber reinforced thermoplastic resins  

NASA Technical Reports Server (NTRS)

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

Navak, R. C.

1977-01-01

90

Thermal residual stresses in amorphous thermoplastic polymers  

NASA Astrophysics Data System (ADS)

An attempt to calculate the internal stresses in a cylindrically shaped polycarbonate (LEXAN-GE) component, subjected to an arbitrary cooling rate, will be described. The differential volume relaxation arising as a result of the different thermal history suffered by each body point was considered as the primary source of stresses build up [1-3]. A numerical routine was developed accounting for the simultaneous stress and structural relaxation processes and implemented within an Ansys® environment. The volume relaxation kinetics was modeled by coupling the KAHR (Kovacs, Aklonis, Hutchinson, Ramos) phenomenological theory [4] with the linear viscoelastic theory [5-7]. The numerical algorithm translates the specific volume theoretical predictions at each body point as applied non-mechanical loads acting on the component. The viscoelastic functions were obtained from two simple experimental data, namely the linear viscoelastic response in shear and the PVT (pressure volume temperature) behavior. The dimensionless bulk compliance was extracted from PVT data since it coincides with the memory function appearing in the KAHR phenomenological theory [7]. It is showed that the residual stress scales linearly with the logarithm of the Biot's number.

Grassia, Luigi; D'Amore, Alberto

2010-06-01

91

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

NASA Technical Reports Server (NTRS)

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

Bryant, Robert G. (Inventor)

1997-01-01

92

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

Microsoft Academic Search

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,

Guillermo A. Jiminez

2006-01-01

93

Plasma spraying of high performance thermoplastics  

SciTech Connect

High performance thermoplastics like the polymers polyphenylene sulfide (PPS) or polyaryletherketone (PAEK) find increasing interest because of their extraordinary properties, i.e. strength and chemical stability, low creep and good electrical insulating even at relatively high temperatures of more than about 200 C. Up o now such materials are mainly processed by injection molding to solid bodies. To produce coatings, which would have numerous applications, no reliable and efficient method exists at present. The high material viscosity and surface tension represent the main obstacles. High velocity plasma and flame spraying with adapted torch nozzles seem to have the potential for the production of dense and well bonded coatings on metal substrates. But special precautions have to be observed and methods applied to get reliable coatings and to overcome the problem of layer shrinking due to recrystallization of the material after spraying which can cause detrimental cracks. These precautions and the adapted process procedure will be described together with the state of polymer coating development.

Henne, R.H.; Schitter, C. [DLR-Inst. of Technical Thermodynamics, Stuttgart (Germany)

1995-12-31

94

Nanofibrous Electrospun Polymers for Reprogramming Human Cells TRAVIS CORDIE,1,2  

E-print Network

Nanofibrous Electrospun Polymers for Reprogramming Human Cells TRAVIS CORDIE,1,2 TY HARKNESS,1 XIN- aprolactone (PCL), thermoplastic polyurethane (TPU) and polypropylene carbonate (PPC)] into nanofiber

Saha, Krishanu

95

Modelling of infrared heating of thermoplastic sheet used in thermoforming process  

Microsoft Academic Search

Thermoforming consists of warming a plastic sheet and forming it into a cavity or over a tool using vacuum, air pressure and mechanical means. The process begins by heating a thermoplastic sheet slightly above the glass transition temperature, for amorphous polymers, or slightly below the melting point, for semi-crystalline materials. As the final thickness distribution of the part is drastically

F. M. Schmidt; Y. Le Maoult; S. Monteix

2003-01-01

96

An investigation into welding of engineering thermoplastics using focused microwave energy  

Microsoft Academic Search

Microwaves have been used for many years in industrial heating applications because of their ability to heat materials volumetrically. The dielectric properties of a material determine its ability to absorb microwave radiation. In this paper, the dielectric properties of engineering thermoplastic materials, which include ultra high molecular weight polyethylene (UHMW PE), polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) polymers under room temperature

Prasad K. D. V Yarlagadda; Tan Chuan Chai

1998-01-01

97

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

Microsoft Academic Search

Thermoplastic polyurethanes are used in a variety of medical devices and experimental tissue engineering scaffolds. Despite advances in polymer composition to improve their stability, the correct balance between chemical and mechanical properties is not always achieved. A model compound (MC) simulating the structure of a widely used medical polyurethane (Pellethane®) was synthesized and reacted with aliphatic and olefinic acyl chlorides

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

2010-01-01

98

Development of a characterization approach for the sintering behavior of new thermoplastics for selective laser sintering  

Microsoft Academic Search

Currently the standard thermoplastic powders for selective laser sintering are based on polyamide12. This leads to restrictions for many applications e.g. in the industrial or medical field. Thus, research on further polymers with enhanced chemical or higher thermal stability plays a major role for applying additive manufacturing to serial production of individual components. Currently, great efforts are made to process

Dietmar Drummer; Dominik Rietzel; Florian Kühnlein

2010-01-01

99

Infrared radiative properties of polyetherimide thermoplastic films  

SciTech Connect

This paper presents an experimental study of the infrared radiative properties of polyetherimide (PEI) thermoplastic films. The complex refractive index of the PEI films is obtained from transmittance measurements of thin film samples with thicknesses of 76 {micro}m (3 mil) and 127 {micro}m (5 mil). The transmittance measurements are performed using a Perkin-Elmer Fourier Transform Infrared (FTIR) Spectrometer. The results are to be used for thermoplastic and thermoplastic composite design/processing and space applications.

Li, D.R.; Phelan, P.E.; Nejhad, M.N.G. [Univ. of Hawaii, Honolulu, HI (United States). Dept. of Mechanical Engineering

1995-12-31

100

Tough, Soluble, Aromatic, Thermoplastic Copolyimides  

NASA Technical Reports Server (NTRS)

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

Bryant, Robert G. (Inventor)

1998-01-01

101

Inelastic behavior of thermoplastic composites  

Microsoft Academic Search

The mechanical behaviors of AS4 reinforced PEKK-based composites were studied. These new thermoplastic composite systems developed by Du Pont exhibit pronounced nonlinear and time dependent behaviors. To characterize the inelastic behavior, classical plasticity and creep theory have been adopted and modified for the orthotropic case by using a one-parameter potential function. The elastic-plastic behavior of LDF(TM) AS-4\\/PEKK system employing aligned,

Chung

1992-01-01

102

Biodegradable Thermoplastic Polyurethanes Incorporating Polyhedral Oligosilsesquioxane  

E-print Network

Biodegradable Thermoplastic Polyurethanes Incorporating Polyhedral Oligosilsesquioxane Pamela T polyurethane (TPU) system that incorporates an organic, biodegradable poly(D,L- lactide) soft block with a hard

Mather, Patrick T.

103

SWNT-Filled Thermoplastic and Elastomeric Composites Prepared by  

E-print Network

SWNT-Filled Thermoplastic and Elastomeric Composites Prepared by Miniemulsion Polymerization Harry nanotube (MWNT) and single wall nanotube (SWNT) filled thermoplastics such as polystyrene (PS),1 poly

Resasco, Daniel

104

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

SciTech Connect

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

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

2009-03-14

105

Joining of thermoplastic substrates by microwaves  

Microsoft Academic Search

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

Felix L. Paulauskas; Thomas T. Meek

1997-01-01

106

Influence of water sorption on mechanical properties of injection-molded thermoplastic denture base resins.  

PubMed

Abstract Objective. This study investigated the influence of water sorption on certain mechanical properties of injection-molded thermoplastic denture base resins. Materials and methods. Six thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate) and a polymethylmethacrylate (PMMA) conventional heat-polymerized denture-based polymer, selected as a control, were tested. Specimens of each denture base material were fabricated according to ISO 1567 specifications and were either dry or water-immersed for 30 days (n = 10). The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the denture base materials were calculated. Results. Water sorption significantly decreased the ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of one of the polyamides and the PMMAs. It also significantly increased the ultimate flexural strength of the polycarbonate. Conclusion. The mechanical properties of some injection-molded thermoplastic denture base resins changed after water sorption. PMID:24850507

Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo; Vallittu, Pekka; Shimizu, Hiroshi; Takahashi, Yutaka

2014-11-01

107

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

SciTech Connect

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

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

1993-12-31

108

Fly ash reinforced thermoplastic vulcanizates obtained from waste tire powder.  

PubMed

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

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

2009-03-01

109

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

Microsoft Academic Search

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

Soroushian; Parviz

2002-01-01

110

Tough soluble aromatic thermoplastic copolyimides  

NASA Technical Reports Server (NTRS)

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

Bryant, Robert G. (Inventor)

2000-01-01

111

Improved thermoplastic materials for offshore flexible pipes  

SciTech Connect

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

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

1988-08-01

112

Absorption of Phthalocyanines in Thermoplastic Media in the 0.5 to 0.8 Micron Region.  

National Technical Information Service (NTIS)

Vanadyl, nickel, copper, and metal-free phthalocyanine were dissolved in liquid and thermoplastic polymer solvents, and optical absorption spectra of the resulting solutions were measured in the 0.5 to 0.8 micron region. Absorption peak frequencies, extin...

E. A. Lucia, C. P. Marino, F. D. Verderame

1967-01-01

113

Development of rheological models for forming flows and picture-frame shear testing of fabric reinforced thermoplastic sheets  

Microsoft Academic Search

The flow of fabric reinforced polymer sheets during sheet-forming processes is dominated by shearing along fibre directions. The goal of this work is to develop models which describe the reheological behaviour of commercially available fabric reinforced thermoplastic sheets. Isotropic and anisotropic models which feature viscous and viscoelastic behaviour and which are suitable for describing processes involving large deformations are developed.

G. B McGuinness; C. M ÓBrádaigh

1997-01-01

114

Formation of aromatic thermoplastic and carbon-fiber prepreg by electrochemical processes  

SciTech Connect

A new technique was developed and demonstrated for combining carbon fibers with aromatic thermoplastic matrices to form a high-quality towpreg. The developed technique utilizes an in-situ electrochemical process (Electrochemical polymerization - ECP) to create the entire polymer matrix surrounding the fiber array by direct polymerization of monomer. Poly-paraxylylene (PPX) and derivatives are successfully polymerized in-situ on carbon fiber surfaces through ECP. A PPX/carbon-fiber towpreg with 40 vol % of matrix is achieved in a fairly short reaction time with a high polymer-coating efficiency. Vapor deposition polymerization (VDP) was also studied. PPX and carbon-fiber towpreg were made successfully by this process. A comparison between ECP and VDP was conducted. A study on electrochemical oxidation (ECO) of carbon fibers was also performed. The ECO treatment may be suitable for carbon fibers incorporated in composites with high-temperature curing resins and thermoplastic matrices.

Li Hong.

1991-01-01

115

Random and systematic error analysis in the complex permittivity measurements of high dielectric strength thermoplastics  

Microsoft Academic Search

This paper presents the complex dielectric permittivity and loss tangent measurements for a selection of advanced polymer-based thermoplastics in the Q-band, V-band and W-band frequencies and discusses in detail the random and systematic errors that arise in the experimental setup. These plastics are reported to have exceptional mechanical, thermal and electrical properties and are extensively used as electrical insulating materials,

Nahid Rahman; Ana I. Medina Ayala; Konstantin A. Korolev; Mohammed N. Afsar; Rudy Cheung; Maurice Aghion

2009-01-01

116

Determination of metal additives and bromine in recycled thermoplasts from electronic waste by TXRF analysis  

Microsoft Academic Search

A new method for analysis of metal additives in recycled thermoplasts from electronic waste was developed, based on dissolving\\u000a the samples in an organic solvent and subsequent analysis of the corresponding solutions or suspensions by total-reflection\\u000a X-ray fluorescence spectroscopy (TXRF). The procedure proved to be considerably less time consuming than the conventional\\u000a digestion of the polymer matrix. Additives containing Ti,

H. Fink; U. Panne; M. Theisen; R. Niessner; T. Probst; X. Lin

2000-01-01

117

PEKK as a new thermoplastic matrix for high-performance composites  

Microsoft Academic Search

A novel semicrystalline polyetherketoneketone (PEKK) polymer is being developed as a potential high-performance thermoplastic matrix system for advanced composites. This resin with upper use temperature between those of Du Pont's K-3 (polyimide) and J-2 (polyamide) has potential advantages versus other commercial organic matrix systems. The carbon-fiber reinforced composite laminates with PEKK matrix prepared from the proprietary melt impregnated tows showed

1988-01-01

118

78 FR 29387 - Government-Owned Inventions, Available for Licensing  

Federal Register 2010, 2011, 2012, 2013

...Quasi-Static Electric Field Generator; NASA Case No.: LAR-18131-1: Puncture-Healing Thermoplastic Resin Carbon-Fiber Reinforced Composites; NASA Case No.: LAR-18089-1: Fluidic Oscillator Array for Synchronized Oscillating...

2013-05-20

119

Computational modelling of a thermoforming process for thermoplastic starch  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

120

Polymers  

NSDL National Science Digital Library

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

2012-10-16

121

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

PubMed

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

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

2012-05-16

122

Elastic effects in the foaming of thermoplastics Celeste Sagui,1  

E-print Network

Elastic effects in the foaming of thermoplastics Celeste Sagui,1 Luc Piche´,1,2 Abdelhadi Sahnoune, and by coalescence. On extrusion to a cooler tempera- ture, the thermoplastic hardens, freezing the bubble distribu

Grant, Martin

123

Thermoplastic Elastomers via polyolefin/Layered Silicate Nanocomposites  

NASA Astrophysics Data System (ADS)

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

Harsha Kalluru, Sri; Cochran, Eric W.

2013-03-01

124

Azobenzene-Containing Thermoplastic Elastomers: Coupling Mechanical and Optical Effects  

E-print Network

Azobenzene-Containing Thermoplastic Elastomers: Coupling Mechanical and Optical Effects Shuying Bai�bec, Canada G1K 7P4 Received July 23, 2001 ABSTRACT: Thermoplastic elastomers of a styrene In this paper, we report on the preparation of a system of azobenzene thermoplastic elastomers

Zhao, Yue

125

Viscoelasticity and Processability of a BAMO/AMMO Thermoplastic  

E-print Network

Viscoelasticity and Processability of a BAMO/AMMO Thermoplastic Elastomer By R. E. Kucukpinar Jersey INTRODUCTION Thermoplastic elastomer based formulations are used widely in various applications on the rheological behavior of the thermoplastic elastomer and processability analysis. In this study, we provide

126

ENG 4793: Composite Materials and Processes 1 Combining Thermoplastics with  

E-print Network

1 ENG 4793: Composite Materials and Processes 1 Combining Thermoplastics with Reinforcing Fibers and Processes 7 Short Fiber Processes Thermoplastic Pellets Chopped Fibers Extruder Strand Die Water Bath Pellets Cooler Rovings Thermoplastic Pellets Counter Flow Die ( USP 5,176,775 ) #12;3 ENG 4793: Composite

Colton, Jonathan S.

127

Hybrid yarn for thermoplastic fibre composites Publications Department  

E-print Network

Hybrid yarn for thermoplastic fibre composites Publications Department publications Hybrid yarn for thermoplastic fibre composites. Summary of technical results Final report for MUP2 Framework Program No. 1994:10:53 #12;Hybrid yarn for thermoplastic fibre composites. Introduction Publications Risø-R-1034 Hybrid yarn

128

Electromechanical instabilities of thermoplastics: Theory and in situ observation  

E-print Network

Electromechanical instabilities of thermoplastics: Theory and in situ observation Qiming Wang://apl.aip.org/about/rights_and_permissions #12;Electromechanical instabilities of thermoplastics: Theory and in situ observation Qiming Wang,1 online 5 October 2012) Thermoplastics under voltages are used in diverse applications ranging from

Zhao, Xuanhe

129

Mathematical Analysis of Thermoplasticity with Linear Kinematic Hardening  

E-print Network

Mathematical Analysis of Thermoplasticity with Linear Kinematic Hardening Krzysztof Che lmi#19;nski #3;y & Reinhard Racke z Abstract We study thermoplasticity with the Prandtl-Reuss ow rule approximation, converges to a global in time solution of the (modi#12;ed) system of thermoplasticity. AMS classi

Racke, Reinhard

130

Atomically smooth surfaces through thermoplastic forming of metallic glass  

E-print Network

Atomically smooth surfaces through thermoplastic forming of metallic glass Golden Kumar,a Peter A September 2010 We demonstrate that atomically smooth surfaces can be generated by thermoplastic forming surface layer from the advancing metallic glass-air interface. The thermoplastically formed surface is two

Gelfond, Michael

131

Finite thermoplasticity with phase changes based on isomorphisms  

E-print Network

Finite thermoplasticity with phase changes based on isomorphisms S. Dachkovski*, M. Bo¨ hm Zentrum be influenced by applied loadings. In this paper a model of finite thermoplasticity with phase changes based of deformations. This approach is free of the shortcomings mentioned before. To model thermoplasticity the notion

Dashkovskiy, Sergey

132

EXTRUSION OF BASO4 MEDICAL-GRADE THERMOPLASTIC POLYURETHANE  

E-print Network

1 EXTRUSION OF BASO4 FILLED MEDICAL-GRADE THERMOPLASTIC POLYURETHANE Guangyu Lu, Dilhan M. Kalyon% (vol.) BaSO4 filled medical-grade (additive free) thermoplastic polyurethanes was investigated. Filled Radiopaque barium sulfate filled thermoplastic polyurethane is widely used in the medical device industry

133

Characteristics of in-air thermoplastic recording.  

PubMed

Concepts and characteristics of in-air thermoplastic recording are reviewed. The in-air method of electrophotographic recording relies upon a gaseous discharge of air molecules to form a latent charge pattern in the likeness of the image. Modulation is achieved with a light sensitive photoreceptor, and images are stored as surface deformations on the thermoplastic film. Development is instantaneous with heat, projection by schlieren optics, and erasure by melting the thermoplastic. The technique has been applied to (1) document type recording, where the entire image appears simultaneously, and (2) the recording of charactron type CRT images, where the information appears as a rapid short-time sequence of high intensity alphanumeric symbols. Problem areas are studied with the aid of the equivalent circuit and its transient analysis. Resolution, reciprocity, photoconductor characteristics, reusability, image sampling, and the effects of humidity are discussed. PMID:20076115

D'Antonio, N F

1969-01-01

134

Experimental simulation of the thermoplastic pultrusion process  

SciTech Connect

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

Squires, C.; Almaraz, J.; O`Toole, B. [Univ. of Nevada, Las Vegas, NV (United States)

1996-12-31

135

Inelastic behavior of thermoplastic composites  

SciTech Connect

The mechanical behaviors of AS4 reinforced PEKK-based composites were studied. These new thermoplastic composite systems developed by Du Pont exhibit pronounced nonlinear and time dependent behaviors. To characterize the inelastic behavior, classical plasticity and creep theory have been adopted and modified for the orthotropic case by using a one-parameter potential function. The elastic-plastic behavior of LDF(TM) AS-4/PEKK system employing aligned, long discontinuous fiber reinforced composites has been studied in comparison with the continuous fiber reinforced counterpart. A dual mode plastic potential action was employed to model the plastic behaviors of these composites at room and elevated temperatures up to 177 C. A one-parameter failure criterion was also applied to predict the failure strength. Off-axis coupon specimens were used to measure the failure strength and generate stress-strain curves from which the elastic-plastic properties were extracted. It was observed that the elastic-plastic performance and strength of LDF(TM) are as good as those of the continuous fiber system. The material constants were determined by using uniaxial creep tests of off-axis coupon specimens. In terms of effective stress and effective creep strain, the anisotropic creep behavior was described by a stress dependent master creep curve irrespective of loading direction relative to fiber orientation. This model was implemented into classical laminate theory to predict the creep behavior of composite laminate, and compared with experimental data of (+/- 45)4s laminate specimens. The influence of thermal stress was included. The micromechanical approach also was tried to model the inelastic behavior of continuous fiber reinforced composites. The fiber was assumed to be orthotropically elastic, and the matrix to conform to the classical elastic-plasticity and creep theories.

Chung, I.

1992-01-01

136

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

NASA Astrophysics Data System (ADS)

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

Sulong, Nurulsaidatulsyida; Rus, Anika Zafiah M.

2013-12-01

137

Process for crosslinking and extending conjugated diene-containing polymers  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

138

Electromechanical instabilities of thermoplastics: Theory and in situ observation  

PubMed Central

Thermoplastics under voltages are used in diverse applications ranging from insulating cables to organic capacitors. Electromechanical instabilities have been proposed as a mechanism that causes electrical breakdown of thermoplastics. However, existing experiments cannot provide direct observations of the instability process, and existing theories for the instabilities generally assume thermoplastics are mechanically unconstrained. Here, we report in situ observations of electromechanical instabilities in various thermoplastics. A theory is formulated for electromechanical instabilities of thermoplastics under different mechanical constraints. We find that the instabilities generally occur in thermoplastics when temperature is above their glass transition temperatures and electric field reaches a critical value. The critical electric field for the instabilities scales with square root of yield stress of the thermoplastic and depends on its Young's modulus and hardening property. PMID:23112349

Wang, Qiming; Niu, Xiaofan; Pei, Qibing; Dickey, Michael D.; Zhao, Xuanhe

2012-01-01

139

Determination of metal additives and bromine in recycled thermoplasts from electronic waste by TXRF analysis.  

PubMed

A new method for analysis of metal additives in recycled thermoplasts from electronic waste was developed, based on dissolving the samples in an organic solvent and subsequent analysis of the corresponding solutions or suspensions by total-reflection X-ray fluorescence spectroscopy (TXRF). The procedure proved to be considerably less time consuming than the conventional digestion of the polymer matrix. Additives containing Ti, Zn, Br, Cd, Sn, Sb, and Pb were analyzed in a hundred randomly selected samples from recycling, which provided an overview of the range of elemental concentrations in thermoplasts utilized for consumer electronics. The results were validated independently by instrumental neutron activation analysis (INAA), subsequent regression analysis confirmed the trueness of the chosen approach. PMID:11220585

Fink, H; Panne, U; Theisen, M; Niessner, R; Probst, T; Lin, X

2000-01-01

140

In-Plane Shear Characterisation of Uni-Directionally Reinforced Thermoplastic Melts  

NASA Astrophysics Data System (ADS)

Intra-ply shear is an important mechanism in hot stamp forming processes of UD fibre reinforced thermoplastic laminates. Various methods have been developed to characterise this shear mechanism, but measured properties may differ for several orders of magnitude. Therefore, an alternative method to characterise the longitudinal shearing viscosity is presented. Straight fibre reinforced thermoplastic bars with a rectangular cross section are subjected to torsional loadings. The specimens' response can be used to characterise the shear properties of the fibre reinforced polymer melt. Different geometries and clamping conditions were modelled to show the sensitivity of the measured viscosity. Based on this, experiments were performed with thick bars with a PEI-AS4 and PEEK-AS4 composition. Frequency sweeps were applied at different temperatures. All measurements showed a clear shear thinning behaviour, which can conveniently be described with a power law model.

Haanappel, S. P.; Ten Thije, R.; Sachs, U.; Rietman, A. D.; Akkerman, R.

2011-05-01

141

Metallic glass mold insert for hot embossing of polymers  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

142

Polymer bonding process for nanolithography  

NASA Astrophysics Data System (ADS)

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.

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

2001-10-01

143

Vegetable Oil Derived Solvent, and Catalyst Free "Click Chemistry" Thermoplastic Polytriazoles  

PubMed Central

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

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

2014-01-01

144

Supplementary information for Electromechanical Instabilities of Thermoplastics: Theory and In Situ Observation  

E-print Network

1 Supplementary information for Electromechanical Instabilities of Thermoplastics: Theory strain curves for unconstrained thermoplastics predicted by the theoretical model. The pull-in instability is indicated by crosses. #12;3 Fig. S2. (a) Equipotential contours in the thermoplastic

Zhao, Xuanhe

145

ASYMPTOTIC AND COMPUTATIONAL ANALYSIS OF LARGE SHEAR DEFORMATIONS OF A THERMOPLASTIC MATERIAL  

E-print Network

ASYMPTOTIC AND COMPUTATIONAL ANALYSIS OF LARGE SHEAR DEFORMATIONS OF A THERMOPLASTIC MATERIAL D. A, asymptotics, finite differences, shear bands, singular perturbations, thermoplastic materials AMS subject of high strain that develop in materials under intense thermoplastic shear deformations. Since they often

Edwards, David A.

146

The use of thermoplastic lined pipelines for aggressive hydrocarbon service  

SciTech Connect

This study is related to the use of thermoplastic liners to control corrosion of new and rehabilitated pipelines carrying aggressive hydrocarbon products. The aim is to investigate the technical and safety issues involved in introducing a thermoplastic liner into an existing carbon steel pipeline for aggressive hydrocarbon service at temperatures up to 150 C and internal pressures up to 34 MPa (5,000 psi). The principle objective is to provide design data for thermoplastic lined pipelines. The scope combines the use of liner insertion techniques with thermoplastic materials widely used in onshore pipelines and demonstrates the effectiveness of thermoplastic linings. The results indicate that thermoplastic liners can be used to control corrosion of pipelines in aggressive hydrocarbon environments.

Woodward, K.A.; Al-Hassan, T. [Health and Safety Executive, Merseyside (United Kingdom). Offshore Safety Div.

1996-12-31

147

Processing Conjugated-Diene-Containing Polymers  

NASA Technical Reports Server (NTRS)

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.

Bell, Vernon L.; Havens, Stephen J.

1987-01-01

148

Crystallinity of On-Line Consolidated Thermoplastic Composites  

Microsoft Academic Search

Processing of high-quality thermoplastic composite parts by laser-assisted tape consolidation involves in-situ melting and solidification of the thermoplastics matrix material. In contrast to autoclave processing, fusion of the matrix material occurs locally, preventing both the development of residual stresses and fiber buckling in the inner layer. High temperature thermoplastics such as Polyetheretherketone (PEEK) or Polyetherketoneketone (PEKK), are semicrystalline. The level

Christoph M. Pistor; Selçuk I. Güçeri

1999-01-01

149

Thermoplastic constructional composite material for radiation protection  

Microsoft Academic Search

The possibility of synthesis of filled metallooligomer powders on the basis of lead ethylsiliconate is considered by a method\\u000a of heterophase interaction, in siloksan chains of which chemically bound lead with a high concentration of atoms of lead is\\u000a contained. Thermoplastic constructional composite materials for radiation protection on the basis of a polystyrene polymeric\\u000a matrix modified by waterproof oligomer lead

V. I. Pavlenko; I. S. Epifanovskii; R. N. Yastrebinskii; O. V. Kuprieva

2011-01-01

150

Challenges in Biomass–Thermoplastic Composites  

Microsoft Academic Search

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

Roger M. Rowell

2007-01-01

151

THERMAL BEHAVIOR DURING THERMOPLASTIC COMPOSITES RESISTANCE WELDING  

Microsoft Academic Search

Two- and three- dimensional heat transfer finite element models of the resistance-welding process for joining thermoplastic composite laminates were developed. The models simulated a resistance welded single lap-shear joint using 16-layer unidirectional APC- 2\\/AS4 laminates. The heating element consisted of a stainless steel metal mesh sandwiched between neat PEEK films. The heat was generated at the bond surface by applying

Edith Talbot; Ali Yousefpour; Pascal Hubert; Mehdi Hojjati

152

Thermoplastic Elastomers with Oligo (ß-Alanine) Hard Segments.  

E-print Network

??Conventional vulcanized rubbers are crosslinked by irreversible covalent bonds. Thermoplastic elastomers (TPEs) are a material with rubbery elasticity at their designed service temperature. TPEs show… (more)

Li, Kai

2014-01-01

153

Reducing the Water Absorption of Thermoplastic Starch Processed by Extrusion.  

E-print Network

??Novel plastics that are biodegradable and made from renewable natural resources are currently being researched as alternatives to traditional petroleum-based plastics. One such plastic, thermoplastic… (more)

Oakley, Philip

2011-01-01

154

Connection between elastic moduli and thermal conductivities of anisotropic short fiber reinforced thermoplastics: theory and  

E-print Network

thermoplastics: theory and experimental verification Igor Sevostianov a, *, Mark Kachanov b a Department by the authors are specified for short fiber reinforced thermoplastics. They are verified by comparison

Sevostianov, Igor

155

Evaluation of microstructure and properties deterioration in short fiber reinforced thermoplastics  

E-print Network

Evaluation of microstructure and properties deterioration in short fiber reinforced thermoplastics. Effective elastic stiffnesses and thermal diffusivities of glass fiber reinforced thermoplastic are measured

Sevostianov, Igor

156

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

E-print Network

Ultrasoft Thermoplastic Polyurethanes This work evolved from collaboration between my laboratory) thermoplastic poly(carbonate urethane)s that do not exhibit surface tackiness. These novel polyurethanes target

Harmon, Julie P.

157

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

PubMed

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

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

2014-01-01

158

PEKK as a new thermoplastic matrix for high-performance composites  

SciTech Connect

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

Chang, I.Y.

1988-07-01

159

Radiation cross-linked polymers: Recent developments and new applications  

Microsoft Academic Search

The purpose of the present paper is to review the innovative and recent applications of radiation cross-linking of polymers that reinforces their dimensional stability in chemically aggressive and high temperature conditions.Radiation cross-linking can be applied to a great number of plastics: thermoplastics, elastomers and thermoplastic elastomers (TPE). Some of them can cross-link on their own, some others need to be

Sophie Rouif

2005-01-01

160

Imprinting of confining sites for cell cultures on thermoplastic substrates  

NASA Technical Reports Server (NTRS)

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

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

1969-01-01

161

Long fiber thermoplastic materials for non-injection molding processes  

SciTech Connect

Materials continue to evolve. Process limitations often prevent the full realization of a materials potential. Thermoplastic composite materials provide benefits beyond mechanical performance. New processes for thermoplastic composite fabrication provide new opportunities for economic growth. This paper summarizes the uses of TP composite materials for non-injection molding processes.

Bowen, S.T. [Polymer Composites Inc., Winona, MN (United States)

1993-12-31

162

Crosslinking of thermoplastic composites using electron beam radiation  

Microsoft Academic Search

The crosslinking of thermoset materials has been clearly demonstrated to improve many desirable physical and chemical properties for composite applications. While thermoplastic resins also offer many advantages for composite applications, they are not crosslinked and, therefore, may not meet the same property criteria as crosslinked thermosets. Electron beams have been used successfully for crosslinking non-reinforced thermoplastic materials. Electron beams have

A. B. Strong; S. R. Black; G. R. Bryce; D. D. Olcott

1991-01-01

163

Tough poly(arylene ether) thermoplastics as modifiers for bismaleimides  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

164

Multiblock thermoplastic polyurethanes for biomedical and shape memory applications  

NASA Astrophysics Data System (ADS)

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.

Gu, Xinzhu

165

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

E-print Network

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

Sitti, Metin

166

Radiation effects on carbon fiber reinforced thermoplastics  

SciTech Connect

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.

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

1993-12-31

167

Trigeminal trophic syndrome treated with thermoplastic occlusion.  

PubMed

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

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

2011-02-01

168

Thermoplastic Green Machining for Textured Dielectric Substrate for Broadband Miniature Antenna  

E-print Network

Thermoplastic Green Machining for Textured Dielectric Substrate for Broadband Miniature Antenna dielectric substrate for a broadband miniature an- tenna was fabricated using a thermoplastic green machining­Ba­Nd­Titania; BBNT) and an epoxy. At first, a thermoplastic compound, consisting of BBNT particles and thermoplastic

Sendur, Gullu Kiziltas

169

Performance of Polymer Coatings Under Forming Conditions  

E-print Network

to examine the in uence of surface roughness and the indenter tip radius on scratch resistance of polymer [24]. Nano scratch tests were conducted by MTS Dynamic nano mechanical probe system. Experiments were conducted on thermoplastics and thermoset... that surface damage of the polymers used as coatings for aesthetic sense to be smaller than the surface it encounters. Mechanical properties of material such as modulus and ductility were found to be important parameters. In nano scratch testing, the higher...

Purohit, Zalak

2012-02-14

170

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

PubMed

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

Wang, Yong; Zhang, Jun

2013-02-15

171

Thermoplastic starch films reinforced with talc nanoparticles.  

PubMed

Nanocomposite films of thermoplastic corn starch (TPS) with talc particles were obtained by thermo-compression in order to study the effect of filler on structure, optical, and thermal properties. Talc increased the films rigid phase, thus their cross-sections resulted more irregular. Talc preferential orientation within matrix and good compatibility between particles and TPS was observed by SEM. Slight crystalline structure changes in TPS matrix were measured by XRD and DSC, due to talc nucleating effect. Randomly dispersed talc nanoagglomerates and individual platelets were assessed by TEM. Laminar morphology and nano-sized particles allowed that nanocomposite films were optically transparent. TPS-talc films resulted heterogeneous materials, presenting domains rich in glycerol and others rich in starch. Talc incorporation higher than 3%, w/w increased softening resistance of the nanocomposites as stated by DMA. Relaxation temperatures of glycerol-rich phase shifted to higher values since talc reduces the mobility of starch chains. PMID:23648028

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

2013-06-20

172

Giant magnetoimpedance effect enhanced by thermoplastic drawing  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

173

Crosslinking of thermoplastic composites using electron beam radiation  

SciTech Connect

The crosslinking of thermoset materials has been clearly demonstrated to improve many desirable physical and chemical properties for composite applications. While thermoplastic resins also offer many advantages for composite applications, they are not crosslinked and, therefore, may not meet the same property criteria as crosslinked thermosets. Electron beams have been used successfully for crosslinking non-reinforced thermoplastic materials. Electron beams have also been used for curing composite thermoset materials. This research utilizes electron beams to crosslink high performance thermoplastic composite materials (PEEK and PPS with glass and carbon fibers). The tensile strength and tensile modulus are compared under various crosslinking conditions. The method is found to have some advantages in potentially improving physical properties of thermoplastic composite materials.

Strong, A.B.; Black, S.R.; Bryce, G.R.; Olcott, D.D. (Brigham Young Univ., Provo, UT (United States))

1991-07-01

174

Influence of oxidized starch on the properties of thermoplastic starch.  

PubMed

Thermoplastic starch was prepared by adding oxidized starches and glycerol together into starch. The addition of oxidized starch improved the rheological properties and also increased the toughness of thermoplastic starch. Compared with TPS30, the elongation at break increased from 126.8% to 152.5% when 5wt% OS 117% was added. Good compatibility of thermoplastic starch between the matrix and oxidized starch was confirmed by SEM. The addition of oxidized starch lowered the storage modulus and glass transition temperature (Tg) of thermoplastic starch, decreasing Tg from 34.1 to 30°C when 10 wt% OS117% was added. The thermal stability of blending was improved by adding oxidized starches, i.e. when 5 wt% OS70% was added, T5% increased from 134 to 156°C. PMID:23688492

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

2013-07-01

175

Development of bonding methods for thermoplastic advanced composites.  

E-print Network

??Given high strength-to-weight and stiffness-to-weight ratios, sandwich composite materials are continually being considered for automotive applications. Thermoplastic materials, while difficult to bond, have an increased… (more)

Nelson, Jared W

2007-01-01

176

Characterization of Glass-Filled Engineering Thermoplastic Composites.  

National Technical Information Service (NTIS)

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...

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

1983-01-01

177

Characterization of polyetheretherketone and other engineering thermoplastics  

SciTech Connect

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.

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

1984-04-13

178

Fully-renewable and degradable thermoplastic elastomers.  

E-print Network

??The most common polymers derived from renewable feedstocks, poly(3-hydroxybutyrate), polyglycolide, and polylactide (PLA), have high stiffness and tensile strength, but are inherently brittle, thus limiting… (more)

Wanamaker, Carolyn Leigh

2009-01-01

179

The quality assurance of heat fused thermoplastic pipeline joints  

E-print Network

THE QUALITY ASSURANCE OF HEAT FUSED THERMOPLASTIC PIPELINE JOINTS A Thesis by LARRY LEE EARLES Submitted to the Graduate College of Texas A&M University in partial fulfillment for the requirements for the degree of MASTER OF SCIENCE... December 1982 Major Subject: Mechanical Engineering THE QUALITY ASSURANCE OF HEAT FUSED THERMOPLASTIC PIPELINE JOINTS A Thesis LARRY LEE EARLES Approved as to style and content by: Mario A. Colaluca (Chairman of Committee) Carl Gerhold (Member...

Earles, Larry Lee

2012-06-07

180

Design implications of fiber orientation in molded thermoplastic composites  

E-print Network

DESIGN IMPLICATIONS OF FIBER ORIENTATION IN MOLDED THERMOPLASTIC COMPOSITES A Thesis by KONSTANTINOS ELEPHTHERIOS BOULIOS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTERS OF SCIENCE May 1991 Major Subject: Mechanical Engineering DESIGN IMPLICATIONS OF FIBER ORIENTATION IN MOLDED THERMOPLASTIC COMPOSITES A Thesis by KONSTANTINOS ELEPHTHERIOS BOULIOS Approved as to style and content by: Alan...

Boulios, Konstantinos Elephtherios

2012-06-07

181

Roles of nanofiller structure on mechanical behavior of thermoplastic nanocomposites  

E-print Network

ROLES OF NANOFILLER STRUCTURE ON MECHANICAL BEHAVIOR OF THERMOPLASTIC NANOCOMPOSITES A Dissertation by JONG IL WEON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of DOCTOR OF PHILOSOPHY August 2005 Major Subject: Mechanical Engineering ROLES OF NANOFILLER STRUCTURE ON MECHANICAL BEHAVIOR OF THERMOPLASTIC NANOCOMPOSITES A Dissertation by JONG IL WEON Submitted to the Office...

Weon, Jong Il

2006-10-30

182

Characterization of acoustic emission signals from particulate filled thermoset and thermoplastic polymeric coatings in four point bend tests  

E-print Network

1 Characterization of acoustic emission signals from particulate filled thermoset and thermoplastic were conducted on two previously characterized particulate filled thermoplastic and thermoset polymeric filled thermoset and thermoplastic coatings. In this study the AE technique was used to examine in

Quartly, Graham

183

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

E-print Network

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

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

2007-01-01

184

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

E-print Network

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 ...

Srivastava, Vikas

185

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

E-print Network

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

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

2007-01-01

186

An investigation of the detrimental impact of trapped air in thermoplastic micro-embossing  

NASA Astrophysics Data System (ADS)

In hot micro-embossing, a thermally softened polymer is forced into the cavities of a patterned stamp. If embossing is performed in normal atmospheric surroundings, it is possible for air to become trapped inside the cavities of the stamp, impeding pattern replication. We present a fast simulation technique that captures the impact of trapped air in the micro-embossing process. The technique can predict the extent of stamp cavity filling for any given stamp design and linear viscoelastic polymer properties, under the assumption that air, once trapped inside a cavity, is unable to escape. We find that the smaller the effective stiffness of the softened polymer relative to the surrounding atmospheric pressure, the more severe the impact of trapped air. Moreover, the trapping of air becomes more detrimental as the widths of stamp cavities become a larger proportion of their lateral spacing. The results of embossing experiments with two widely used thermoplastic polymers, Zeonor 1060R and polymethylmethacrylate, agree with simulation results and indicate that there is little permeation of trapped air in these materials during a typical embossing process of up to 15 min duration, carried out at between 5 and 45 °C above their glass-transition temperatures.

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

2010-06-01

187

Effect of thermal history on the rheology of thermoplastic polyurethanes  

NASA Astrophysics Data System (ADS)

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.

Yoon, Pil Joong

188

2-D Simulations of Orientation in Highly Concentrated Short Glass Fiber Thermoplastic Composites Made by Injection Molding  

E-print Network

2-D Simulations of Orientation in Highly Concentrated Short Glass Fiber Thermoplastic Composites microscopy. Introduction Injection molded, short-glass fiber thermoplastic composites are an attractive

Wapperom, Peter

189

Process-property studies of weld line strength and thin structure flow in high performance injection molded thermoplastics  

NASA Astrophysics Data System (ADS)

The effects of operator controllable injection molding process parameters on weld line strength and thin structure flow of neat and short fiber reinforced injection molded polyetherimide and PEEK thermoplastics have been investigated using statistical experimental methods. Buckingham's Theorem was used to create empirical models which are consistent with the physics governing injection molding, relating processing to properties. In addition, a fundamental analysis of polymer flow in thin channels has been used to define dimensionless numbers relating processing parameters to material properties. This approach gives insight into the effects of scaling on part properties in injection molding.

Griffing, J. S.; Seferis, J. C.; Kenny, J. M.; Nicolais, L.

190

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

E-print Network

THERMOPLASTIC COMPOSITES Gregorio M. Vélez-García, Kevin Ortman, Aaron P.R. Eberle, Peter Wapperom, and Donald G of the fiber orientation. Introduction Fiber reinforced thermoplastic made by injection molding

Wapperom, Peter

191

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

E-print Network

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

Taylor, Hayden Kingsley

2009-01-01

192

Reduced Cost Fabrication of Large Composite Aerospace Structures Through Nanoparticle Modification of Thermoplastics (Preprint).  

National Technical Information Service (NTIS)

To achieve superior mechanical properties and environmental durability in semi-crystalline engineering thermoplastic composites an intermediate degree of molecular ordering is required. While many thermoplastics achieve their potential crystallinities wit...

D. Marchant, G. R. Yandek, J. M. Mabry, M. Lamontia, M. B. Gruber

2007-01-01

193

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

Microsoft Academic Search

More and more polymer wastes are generated by industry and householders today. Recycling is an important process to reduce the amount of waste resulting from human activities. Currently, recycling technologies use relatively homogeneous polymers because hand-sorting waste is costly. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. At present, most waste

F?rat Burat; Ali Gueney; M. Olgaç Kangal

2009-01-01

194

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

Microsoft Academic Search

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,

James Lunt

1998-01-01

195

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

196

Process analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy.  

PubMed

An experimental setup for direct elemental analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy (LIPS, or laser-induced breakdown spectroscopy, LIBS) was realized. The combination of a echelle spectrograph, featuring a high resolution with a broad spectral coverage, with multivariate methods, such as PLS, PCR, and variable subset selection via a genetic algorithm, resulted in considerable improvements in selectivity and sensitivity for this complex matrix. With a normalization to carbon as internal standard, the limits of detection were in the ppm range. A preliminary pattern recognition study points to the possibility of polymer recognition via the line-rich echelle spectra. Several experiments at an extruder within a recycling plant demonstrated successfully the capability of LIPS for different kinds of routine on-line process analysis. PMID:12236340

Fink, Herbert; Panne, Ulrich; Niessner, Reinhard

2002-09-01

197

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

E-print Network

Page 1 IMPROVEMENT IN THE SIMULATION OF INJECTION MOLDED SHORT GLASS FIBER THERMOPLASTIC COMPOSITES Abstract The mechanical properties of injection molded short-fiber reinforced thermoplastic composite parts to frontal flow and the walls. Introduction This Fiber reinforced thermoplastics made by injection molding

Wapperom, Peter

198

Assessment of Enhanced Autofluorescence and Impact on Cell Microscopy for Microfabricated Thermoplastic Devices  

E-print Network

Thermoplastic Devices Edmond W. K. Young, Erwin Berthier, and David J. Beebe* Department of Biomedical, Madison, Wisconsin 53705, United States ABSTRACT: Thermoplastics such as polystyrene (PS) and cyclo of a number of attractive properties. However, thermoplastics are also known to exhibit autofluorescence

Beebe, David J.

199

Photoactive Thermoplastic Elastomers of Azobenzene-Containing Triblock Copolymers Prepared through Atom Transfer Radical  

E-print Network

Photoactive Thermoplastic Elastomers of Azobenzene-Containing Triblock Copolymers Prepared through to prepare a new series of ABA triblock copolymers that are photoactive thermoplastic elastomers. The samples interesting features to this type of thermoplastic elastomers. When the solution-cast film is stretched

Zhao, Yue

200

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

E-print Network

Improvements in the Simulation of Orientation in Injection Molding of Short Fiber Thermoplastic Abstract The mechanical properties of injection molded short-fiber reinforced thermoplastic composite parts reinforced thermoplastic made by injection molding is an attractive technology to develop lightweight, high

Wapperom, Peter

201

Reduced fibre breakage in a glass-fibre reinforced thermoplastic through foaming  

E-print Network

Reduced fibre breakage in a glass-fibre reinforced thermoplastic through foaming G. Zhang, M of vehicles, one sees increased usage of reinforced thermoplastic composites for their molded parts. Increased for this growth [1]. These thermoplastic composites incorporate discontinuous glass fibres, either long (1­25 mm

Thompson, Michael

202

Microstructural Characterization of Polymers with Positrons  

NASA Technical Reports Server (NTRS)

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.

Singh, Jag J.

1997-01-01

203

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

204

Rheological properties of amorphous and semicrystalline polylactic acid polymers  

Microsoft Academic Search

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

Qi Fang; Milford A Hanna

1999-01-01

205

Surface-Initiated ARGET ATRP and Characterization of Thermoplastic Elastomer Montomorillonite Composites  

NASA Astrophysics Data System (ADS)

Polymer nanocomposites, with enhanced properties as compared to their bulk polymer counterparts, are becoming more prominent in advanced material applications. Here we report the synthesis of poly(n-butyl acrylate-b-styrene) (PBA-b-PS) from the surface of functionalized montmorillonite clay via activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP). The ARGET mechanism allows for a substantial reduction in the amount of transition metal catalyst required. It also exhibits potential for eventual scale-up and the industrial adoption of ATRP as a versatile method for producing polymers with well-defined compositions and functionalities. The composite materials resemble traditional thermoplastic elastomer triblock copolymers, with the clay platelets dividing the central, rubbery PBA block. We used SAXS, NMR, and TEM to characterize the composition and structure of the composites. The resulting material properties were measured by tensile testing, dynamic mechanical analysis, and TGA. We anticipate the composites to have exceptional barrier properties due to the high degree of clay dispersion, which may lead to applications as recyclable packaging materials.

Easley, Jeffrey; Beck, Amanda; Ellison, Christopher

2010-03-01

206

Thermoplastic Explosive Compositions on the Base of Hexanitrohexaazaisowurtzitane  

NASA Astrophysics Data System (ADS)

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.

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

2006-08-01

207

LARC-TPI: A multi-purpose thermoplastic polyimide  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

208

Thermoplastic veils as advanced modifiers for multifunctional fiber reinforced composites  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

209

Thermal analysis and crystallization kinetics of high-temperature thermoplastics  

SciTech Connect

Thermoplastic resins possess increased toughness with improved damage tolerance and low sensitivity to the effects of moisture; they also promise significant production cost reductions and maintainability enhancements. A thermal analysis is presently conducted comparing the microstructural kinetics of the thermoplastic resins APC-2, which is PEEK type, and APC, which is an HTX resin, on the basis of differential scanning calorimetry. Attention is given to the development of expressions for the prediction of the degree of crystallinity derivable from the processing and annealing conditions to which laminates employing these matrix resins are subjected. Thermal stabilities are compared by means of thermogravimetric analysis. 5 references.

Carpenter, J.F.

1988-02-01

210

Design of bioabsorbable, amorphous polymer networks and composites  

Microsoft Academic Search

Amorphous, crosslinked, bioabsorbable polymers have been developed as an alternative to conventional linear, semi-crystalline thermoplastic bioabsorbable polymers, and as matrix resins for totally bioabsorbable composites. Bioabsorbable composites have been fabricated, consisting of poly(glycolic acid) surgical mesh embedded in polyester and polyester-urethane based matrices. Low-molecular weight precursors used in the matrices of the composites were based on D, L-lactide and [epsilon]-caprolactone

Wiggins

1992-01-01

211

Microinjection moulding of polymer microfluidic devices  

Microsoft Academic Search

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

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

2009-01-01

212

Processing and characterization of unidirectional thermoplastic nanocomposites  

NASA Astrophysics Data System (ADS)

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.

Narasimhan, Kameshwaran

213

Monitoring the resistance welding of thermoplastic composites through acoustic emission  

Microsoft Academic Search

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

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

1992-01-01

214

A model for a thermoplastic pultrusion process using commingled yarns  

Microsoft Academic Search

A pultrusion process using thermoplastic commingled yarns as raw material has been studied. In such a process, the degree of impregnation is one of the most important parameters affecting the mechanical properties of the final product. The degree of impregnation was estimated by dual-scale porous media flow models, including microscopic impregnating flow and macroscopic resin flow. Dimensionless parameters were adopted

Dae-Hwan Kim; Woo Il Lee; Klaus Friedrich

2001-01-01

215

Heat flow analysis in connection with thermoplastic filament winding  

Microsoft Academic Search

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

Anders Brage; Charles Lamrell

1988-01-01

216

Thermal performance of thermoplastic natural rubber solar collector  

Microsoft Academic Search

The paper presents the thermal performance of a solar collector with TPNR (thermoplastic natural rubber) tubing as the absorber plate. A commercial blend of TPNR (dynamically vulcanised natural rubber—DVNR 9011) was used as the absorber plate which was of the parallel type and satisfies the test conditions indicated by the standard GB 4271-84. The values of the thermal performance parameters

K. Sopian; R. Zulkifli; J. Sahari; M. Y. Othman

2002-01-01

217

Photoconductor-thermoplastic devices for holographic nondestructive testing  

Microsoft Academic Search

Although photoconductor-thermoplastic devices have been considered for holographic applications in the past, they suffered from limited recording bandwidth and poor noise characteristics; as a consequence, they were confined to recording holograms of relatively small objects. In this paper techniques for improving the spatial bandwidth to 1500 lines\\/mm are described. Furthermore, the frost formation mechanism was investigated, and means for suppressing

A. A. Friesem; Y. Katzir; Z. Rav-Noy; B. Sharon

1980-01-01

218

Development and evaluation of thermoplastic street maintenance material  

NASA Technical Reports Server (NTRS)

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.

Siemens, W. D.

1973-01-01

219

Multi-layer thermoplastic composites manufacturing processes: simulations and experiments  

Microsoft Academic Search

Press forming of multi-layer thermoplastic composite laminates is a fast and cost-effective method to produce thin shelled products. This paper shows that virtual forming provides designers with a tool to determine and to optimize the formability of these composite products. Forming simulations identify critical spots in the product design at an early stage and reduce costly product development times. Accurate

Thije ten René; Sebastiaan Haanappel

2011-01-01

220

Thermoplasticity Model for Concrete under Transient Temperature and Biaxial Stress  

Microsoft Academic Search

In the past, the theory of thermoplasticity has been confined to metal type materials exhibiting an elastic-perfectly-plastic behaviour. This paper describes the application of this theory to modelling the response of a nonlinear hardening material (concrete in the present case) under transient temperature and stress. The difficulties arising from the application of the theory of thermoelastoplasticity to modelling the behaviour

A. Khennane; G. Baker

1992-01-01

221

Characterization of thermoplastic polyamide composite matrix material  

SciTech Connect

The research described here involves a study for a representative matrix resin, the J1-polymer (a polyamide) proposed by DuPont. The research was conducted in parallel with related studies, primarily by other personnel, of graphite fiber/J1-polymer unidirectional composites. X-ray and transmission electron microscopy studies were conducted to examine the structure/morphology of the neat resin. Thermal analysis by differential scanning calorimetry was used to investigate the effects of different heating and cooling rates and various processing conditions. Dynamic mechanical properties of the neat resin were characterized. The fundamental mechanisms of deformation and failure, including creep, crack growth and fracture behaviors, were examined both at room temperature and at elevated temperature. A number of the techniques were extended to characterize the composite as well as the neat resin.

Chen, W.L.A.

1987-01-01

222

Electron Beam Crosslinked Polyurethane Shape Memory Polymers with Tunable Mechanical Properties  

PubMed Central

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.

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

2014-01-01

223

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

PubMed

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

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

2010-07-01

224

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

NASA Technical Reports Server (NTRS)

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.

Theil, Michael H.

1988-01-01

225

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

NASA Technical Reports Server (NTRS)

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.

Pater, Ruth H. (inventor)

1992-01-01

226

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

Microsoft Academic Search

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

W. Hufenbach; M. Gude; T. Heber

2009-01-01

227

Soft and Strong Thermoplastic Elastomers Through Molecular Design  

NASA Astrophysics Data System (ADS)

Thermoplastic elastomers (TPE) that have a low linear modulus and yet are strong at large extension are of great importance in a variety of technological applications. Current TPE designs based on ABA triblock copolymers are limited in that the maximum volume fraction of the hard A blocks, which correlates with the material strength, is restricted by the constraint that the A domains be discrete while the soft B domains are continuous. In this study, we have investigated new designs of TPEs that utilize polydispersity of the hard blocks in tandem with novel block architectures to control morphology in microphase separated AB block copolymers. Self-consistent field theory calculations confirm that these designs stabilize spherical and cylindrical phases at higher volume fractions of the hard blocks, with the maximum volume fraction of the hard block in some cases approaching twice that of a conventional ABA thermoplastic elastomer.

Oyerokun, Folusho; Fredrickson, Glenn; Handlin, Dale

2008-03-01

228

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

PubMed Central

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

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

2014-01-01

229

Joining of aluminum and long fiber thermoplastic (LFT) composites  

NASA Astrophysics Data System (ADS)

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.

Kulkarni, Rahul R.

230

Study of Time-Dependent Properties of Thermoplastics  

Microsoft Academic Search

Simple tests carried out with a common tension\\/compression testing machine are used to obtain timedependent properties of non-reinforced thermoplastics. These tests include ramp loadings as well as relaxation and creep tests. Two materials (PBT Celanex 2002-2 and POM Hostaform C9021, Ticona GmbH, Kelsterbach) were taken for the experiments. The experiments show that an adequate description of the long-term material properties

V. A. Kolupaev; A. Bolchoun; H. Altenbach

2010-01-01

231

Biodegradation of a Starch Containing Thermoplastic in Standardized Test Systems  

Microsoft Academic Search

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

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

232

Poly (butylensuccinate co-adipate)thermoplastic starch nanocomposite blends  

Microsoft Academic Search

Nanocomposites based on blends of thermoplastic corn starch (TPS), plasticized with glycerol, and poly (butylensuccinate co-adipate) (PBAS) were prepared using sodium montmorillonite and organomodified montmorillonite. X-ray diffraction and scanning electron microscopy were used to study the clay dispersion. The effects of PBAS and clay type content on mechanical properties were evaluated. TPS\\/PBAS\\/organic modified montmorillonite shows an exfoliated nanocomposite structure and

S. Bocchini; D. Battegazzore; A. Frache

2010-01-01

233

Infrared speckle photography on a metal thermoplastic carrier  

NASA Astrophysics Data System (ADS)

Direct implementation of the speckle photography in the IR region of the spectrum on a metal thermoplastic carrier is performed. Consideration is made of the main advantages of speckle photography in the IR region. The method of recording is described, the basic characteristics of the used devices, elements and media as well as the experimental results on IR radition at 1.06 and 10.6 ?m are presented.

Achasov, O. V.; Belkin, V. G.; Blinkov, G. N.; Kukharchik, P. L.; Skripko, A. S.; Fomin, N. A.

1988-10-01

234

Electron beam modification of thermoplastic elastomeric blends made from polyolefins  

Microsoft Academic Search

Thermoplastic elastomeric films have been prepared from blends of ethylene vinylacetate copolymer (EVA) with low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP) by electron beam modification in presence of radiation sensitizer. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) have been used to evaluate the structural changes of these blends. Scanning electron microscopy (SEM) indicates the morphological features of

S. Chattopadhyay; T. K. Chaki; A. K. Bhowmick

2001-01-01

235

Accelerated Hygrothermal and UV Aging of Thermoplastic Polyurethanes  

Microsoft Academic Search

Thermoplastic polyurethanes (PU) were prepared from 4,4'-diphenyl methane diisocyanate (MDI), polyether polyol and 1,4 butane diol with and without a hindered amine light stabilizer (Tinuvin®-123) and UV absorber (Tinuvin®-400). The accelerated hygrothermal and UV aging were performed at different humidity and aging temperatures for 720, 1440, and 2160 h of exposure, in a Thermotron environmental chamber and QUV chamber, respectively.

R. N. Jana; H. Bhunia

2010-01-01

236

Modeling Fatigue Damage in Long-Fiber Thermoplastics  

Microsoft Academic Search

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

Ba Nghiep Nguyen; Vlastimil Kunc; Satish K. Bapanapalli

2009-01-01

237

Thermoset-thermoplastic aromatic polyamide containing N-propargyl groups  

NASA Technical Reports Server (NTRS)

The compounds of the class of aromatic polyamides useful as matrix resins in the manufacture of composites or laminate fabrication were developed. The process for preparing this thermoplastic-thermoset polyamide system involves incorporating a latent crosslinking moiety along the backbone of the polyamide to improve the temperature range of fabrication thereof wherein the resin softens at a relatively low temperature (approx. 154 C) and subsequently sets-up or undergoes crosslinking when subjected to higher temperature (approx. 280 C).

St.clair, T. L.; Wolfe, J. F.; Greenwood, T. D. (inventors)

1984-01-01

238

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

NASA Astrophysics Data System (ADS)

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.

Jiminez, Guillermo A.

239

Material, process, and product design of thermoplastic composite materials  

NASA Astrophysics Data System (ADS)

Thermoplastic composites made of polypropylene (PP) and E-glass fibers were investigated experimentally as well as theoretically for two new classes of product designs. The first application was for reinforcement of wood. Commingled PP/glass yarn was consolidated and bonded on wood panel using a tie layer. The processing parameters, including temperature, pressure, heating time, cooling time, bonding strength, and bending strength were tested experimentally and evaluated analytically. The thermoplastic adhesive interface was investigated with environmental scanning electron microscopy. The wood/composite structural design was optimized and evaluated using a Graphic Method. In the second application, we evaluated use of thermoplastic composites for explosion containment in an arrester. PP/glass yarn was fabricated in a sleeve form and wrapped around the arrester. After consolidation, the flexible composite sleeve forms a solid composite shell. The composite shell acts as a protection layer in a surge test to contain the fragments of the arrester. The manufacturing process for forming the composite shell was designed. Woven, knitted, and braided textile composite shells made of commingled PP/glass yarn were tested and evaluated. Mechanical performance of the woven, knitted, and braided composite shells was examined analytically. The theoretical predictions were used to verify the experimental results.

Dai, Heming

240

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

241

Morphology of Thermoplastic Elastomers:Stereoblock Polypropylene  

SciTech Connect

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.

Pople, John A

2002-08-06

242

Tribology of polymer composites  

SciTech Connect

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

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

1993-12-31

243

LaRC TPI 1500 series polymers  

NASA Technical Reports Server (NTRS)

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.

Hou, Tan-Hung; Bai, Jia-Mo

1990-01-01

244

Application of radiation-chemical technology to the manufacture of polymer-based materials and products  

Microsoft Academic Search

This report describes research in the areas of: cross-linking of thermoplastics; curing of oligomer-monomer compositions for obtaining various compounds, and curing of adhesives for obtaining flockulated materials on a polymer support. The efficiency of the processes is stressed.

V. S. Ivanov; N. A. Kalinina; I. I. Migunova

1993-01-01

245

Diode laser welding for packaging of transparent micro-structured polymer chips  

Microsoft Academic Search

Laser transmission welding in recent years has been established as a versatile method for interconnection of thermoplastics, at least for macroscopic parts. The technology also offers interesting possibilities for packaging of transparent, micro-structured polymer chips, as used for life science or biotechnology applications. A method for transmission welding, based on a diode laser bar in combination with a thin layer

T. Klotzbuecher; M. Letschert; T. Braune; K.-S. Drese; T. Doll

2006-01-01

246

Thermally and flow induced crystallization of polymers at low shear rate  

Microsoft Academic Search

In semi-crystalline thermoplastic products, final properties are strongly dependent on the thermo-mechanical history experienced by the polymer melt during processing. More precisely, structural heterogeneities such as rigidity gradients and shrinkage anisotropy are directly related to the crystalline microstructure. Therefore, accurate prediction of part properties by a processing computer simulation code requires the implementation of an appropriate crystallization kinetics model, including

M’hamed Boutaous; Patrick Bourgin; Matthieu Zinet

2010-01-01

247

Buried thermoplastic layer diagnostics by the use of combined frequency-domain and impulse response photo-thermo-mechanical radiometry  

E-print Network

Buried thermoplastic layer diagnostics by the use of combined frequency- domain and impulse to the problem of characterizing the thermoplastic layer thickness sandwiched between two metal foils used component due to the thermal expansion of the thermoplastic layer, is presented. The time domain impulse

Mandelis, Andreas

248

Laser-bonding of long fiber thermoplastic composites for structural assemblies  

Microsoft Academic Search

The use of laser light for bonding of long fiber reinforced thermoplastic composites (LFTPC) offers new possibilities to overcome the constraints of conventional joining technologies. Laser specific transmission welding procedures are known in manufacturing of short fiber thermoplastic composites. The technical basics of the joining process and an outline of some material inherent characteristics using long glass fiber reinforced composites

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

2010-01-01

249

High-speed laser cutting of superposed thermoplastic films: thermal modeling and process characterization  

Microsoft Academic Search

Common thermoplastic films used in the packaging industry have a thickness lower than 100?m, and present low absorption to CO2 laser radiation. This characteristic renders the use of cutting parameters, predicted by models developed for thicker thermoplastics inappropriate. In addition, the usual procedures involve the use of an assisting gas, responsible for removing the melted material, which, when processing thin

João M. P. Coelho; Manuel A. Abreu; F. Carvalho Rodrigues

2004-01-01

250

Three-dimensional microstructuring of carbon by thermoplastic spacer evaporation during pyrolysis  

E-print Network

Three-dimensional microstructuring of carbon by thermoplastic spacer evaporation during pyrolysis by using a novel low-cost process that involved thermoplastic spacer (paraffin wax) evap- oration during mask application, UV exposure, development and pyrolysis. In case of three-dimen- sional

Chung, Deborah D.L.

251

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

Microsoft Academic Search

A thermoplastic mask is used to immobilize the patient head during radiotherapy. It also enhances the absorbed dose distribution improving the radiotherapic treatment. In this work we investigate the influence of the thermoplastic material in the phantom surface and in the target volume region. For the measurements a Fricke Xylenol Gel dosimeter, based on Fe (II) to Fe (III) oxidation,

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

2009-01-01

252

3D Microstructure Manufacture based on laser-induced thermoplastic expansion  

Microsoft Academic Search

In this paper, we describe a novel technology for three dimensional (3D) microstructure manufacture, which is based on the laser-induced thermoplastic expansion. A thermoplastic material melted by laser heating grows in the surrounding space filled with liquid, and after the laser irradiation is switched off, it immediately solidifies into a protuberant shape because of the heat release to the liquid

Wang Leyan; Zhang Dongxian; Zhang Haijun

2006-01-01

253

Characterization of high performance filled thermoplastics via capillary rheometry: Final report  

SciTech Connect

The rheological characteristics of five engineering thermoplastics were evaluated. Each of these materials are high performance thermoplastics used in the injection molding process. Rheological data determined through this study will be extremely useful in predicting the flow behavior of injection molded materials as well as in determining the consistency of properties between various lots of the same material. 2 refs.

Smith, B.P.

1989-02-01

254

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

PubMed Central

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.

Mengeloglu, Fatih; Karakus, Kadir

2008-01-01

255

Induction Consolidation of Thermoplastic Composites Using Smart Susceptors  

SciTech Connect

This project has focused on the area of energy efficient consolidation and molding of fiber reinforced thermoplastic composite components as an energy efficient alternative to the conventional processing methods such as autoclave processing. The expanding application of composite materials in wind energy, automotive, and aerospace provides an attractive energy efficiency target for process development. The intent is to have this efficient processing along with the recyclable thermoplastic materials ready for large scale application before these high production volume levels are reached. Therefore, the process can be implemented in a timely manner to realize the maximum economic, energy, and environmental efficiencies. Under this project an increased understanding of the use of induction heating with smart susceptors applied to consolidation of thermoplastic has been achieved. This was done by the establishment of processing equipment and tooling and the subsequent demonstration of this fabrication technology by consolidating/molding of entry level components for each of the participating industrial segments, wind energy, aerospace, and automotive. This understanding adds to the nation's capability to affordably manufacture high quality lightweight high performance components from advanced recyclable composite materials in a lean and energy efficient manner. The use of induction heating with smart susceptors is a precisely controlled low energy method for the consolidation and molding of thermoplastic composites. The smart susceptor provides intrinsic thermal control based on the interaction with the magnetic field from the induction coil thereby producing highly repeatable processing. The low energy usage is enabled by the fact that only the smart susceptor surface of the tool is heated, not the entire tool. Therefore much less mass is heated resulting in significantly less required energy to consolidate/mold the desired composite components. This energy efficiency results in potential energy savings of {approx}75% as compared to autoclave processing in aerospace, {approx}63% as compared to compression molding in automotive, and {approx}42% energy savings as compared to convectively heated tools in wind energy. The ability to make parts in a rapid and controlled manner provides significant economic advantages for each of the industrial segments. These attributes were demonstrated during the processing of the demonstration components on this project.

Matsen, Marc R

2012-06-14

256

Time Issues in Semi-Crystalline Thermoplastics Processing  

NASA Astrophysics Data System (ADS)

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

Iannone, Michele

2010-06-01

257

Electron beam surface modifications in reinforcing and recycling of polymers  

NASA Astrophysics Data System (ADS)

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.

Czvikovszky, T.; Hargitai, H.

1997-08-01

258

Tunable wetting of polymer surfaces.  

PubMed

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

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

2012-10-16

259

A simple and high production rate manufacturing method for submicron polymer fibres.  

PubMed

The manufacturing technique for cotton-candy floss, heat-aided rotary jet-spinning, was used to produce submicron-scale fibrous meshes by using bioabsorbable thermoplastic polymers. The method was feasible for 100 wt% polymer concentrations functioning completely without solvents. It was possible to produce submicron diameter fibres using a simple device, which indicates that this manufacturing method is a very promising technique for obtaining high-throughput rates for submicron, and possibly nano-scale, fibrous meshes. PMID:21485008

Huttunen, Mikko; Kellomäki, Minna

2011-08-01

260

Capillary Force Lithography: Fabrication of Functional Polymer Templates as Versatile Tools for Nanolithography  

Microsoft Academic Search

The implementation of high-resolution polymer templates fabricated by capillary force lithography (CFL) is explored both in nanoimprint lithography (NIL) and in the wet-etching of metals. Several different thermoplastic and UV-curable polymers and types of substrates are incorporated into the general CFL procedure to meet the diverging requirements of these two applications. The mechanical stability of UV-curable templates for imprinting in

Christiaan M. Bruinink; Mária Peter; Pascale A. Maury; Boer de Meint; Laurens Kuipers; Jurriaan Huskens; David N. Reinhoudt

2006-01-01

261

Simple replication methods for producing nanoslits in thermoplastics and the transport dynamics of double-stranded DNA through these slits.  

PubMed

Mixed-scale nano- and microfluidic networks were fabricated in thermoplastics using simple and robust methods that did not require the use of sophisticated equipment to produce the nanostructures. High-precision micromilling (HPMM) and photolithography were used to generate mixed-scale molding tools that were subsequently used for producing fluidic networks into thermoplastics such as poly(methyl methacrylate), PMMA, cyclic olefin copolymer, COC, and polycarbonate, PC. Nanoslit arrays were imprinted into the polymer using a nanoimprinting tool, which was composed of an optical mask with patterns that were 2-7 µm in width and a depth defined by the Cr layer (100 nm), which was deposited onto glass. The device also contained a microchannel network that was hot embossed into the polymer substrate using a metal molding tool prepared via HPMM. The mixed-scale device could also be used as a master to produce a polymer stamp, which was made from polydimethylsiloxane, PDMS, and used to generate the mixed-scale fluidic network in a single step. Thermal fusion bonding of the cover plate to the substrate at a temperature below their respective T(g) was accomplished by oxygen plasma treatment of both the substrate and cover plate, which significantly reduced thermally induced structural deformation during assembly: ?6% for PMMA and ?9% for COC nanoslits. The electrokinetic transport properties of double-stranded DNA (dsDNA) through the polymeric nanoslits (PMMA and COC) were carried out. In these polymer devices, the dsDNA demonstrated a field-dependent electrophoretic mobility with intermittent transport dynamics. DNA mobilities were found to be 8.2 ± 0.7 × 10(-4) cm(2) V(-1) s(-1) and 7.6 ± 0.6 × 10(-4) cm(2) V(-1) s(-1) for PMMA and COC, respectively, at a field strength of 25 V cm(-1). The extension factors for ?-DNA were 0.46 in PMMA and 0.53 in COC for the nanoslits (2-6% standard deviation). PMID:20938506

Chantiwas, Rattikan; Hupert, Mateusz L; Pullagurla, Swathi R; Balamurugan, Subramanian; Tamarit-López, Jesús; Park, Sunggook; Datta, Proyag; Goettert, Jost; Cho, Yoon-Kyoung; Soper, Steven A

2010-12-01

262

3D thermoplastic elastomer microfluidic devices for biological probe immobilization.  

PubMed

Microfluidics has emerged as a valuable tool for the high-resolution patterning of biological probes on solid supports. Yet, its widespread adoption as a universal biological immobilization tool is still limited by several technical challenges, particularly for the patterning of isolated spots using three-dimensional (3D) channel networks. A key limitation arises from the difficulties to adapt the techniques and materials typically used in prototyping to low-cost mass-production. In this paper, we present the fabrication of thin thermoplastic elastomer membranes with microscopic through-holes using a hot-embossing process that is compatible with high-throughput manufacturing. The membranes provide the basis for the fabrication of highly integrated 3D microfluidic devices with a footprint of only 1 × 1 cm(2). When placed on a solid support, the device allows for the immobilization of up to 96 different probes in the form of a 10 × 10 array comprising isolated spots of 50 × 50 ?m(2). The design of the channel network is optimized using 3D simulations based on the Lattice-Boltzmann method to promote capillary action as the sole force distributing the liquid in the device. Finally, we demonstrate the patterning of DNA and protein arrays on hard thermoplastic substrates yielding spots of excellent definition that prove to be highly specific in subsequent hybridization experiments. PMID:22041708

Brassard, Daniel; Clime, Liviu; Li, Kebin; Geissler, Matthias; Miville-Godin, Caroline; Roy, Emmanuel; Veres, Teodor

2011-12-01

263

Injection Molding of Flat Glass Fiber Reinforced Thermoplastics  

NASA Astrophysics Data System (ADS)

During an injection molding of composite materials, fiber attrition occurs and the average fiber length is reduced. In order to control the breakage of fibers and degradation of mechanical properties during processing, Flat glass Fiber (FF), that has oval cross-section shape, has been developed to use for glass fiber reinforced thermoplastic (GFRTP). Using FF as reinforcement of GFRTP has advantages as following: (1) Fluidity of FF is better than conventional Normal glass Fiber (NF) with 'circular' cross-section; (2) Fiber breakage during the injection molding process using FF is smaller than that using NF. In this study, the mechanical properties of FF and NF were compared for reinforcement of long fiber thermoplastics pellets (LFT pellets). We have also investigated the effect of screw design on fiber damage and the mechanical properties. The mechanical properties of specimens molded by FF reinforcement LFT (FF-LFT) pellets were superior to these of NF reinforcement LFT (NF-LFT) pellets. The former could give composites with higher fluidity and longer residual fiber length. Moreover, FF was able to strengthen injection-molded samples with higher fiber content than NF. Low shear type screw was effective to prevent the fiber attrition during plasticization process, hence leads to better mechanical properties of GFRTP

Tanaka, Kazuto; Katayama, Tsutao; Tanaka, Tatsuya; Anguri, Akihiro

264

Interlaminate Deformation in Thermoplastic Composite Laminates: Experimental-Numerical Correlation  

NASA Astrophysics Data System (ADS)

The interlaminar deformation behaviors of thermoplastic AS4/PEEK composite laminates subjected to static tensile loading are investigated by means of microscopic moiré interferometry with high spatial resolution. The fully threedimensional orthotropic elastic-plastic analysis of interlaminar deformation for the thermoplastic laminates is developed in this paper, and used to simulate the stress-strain curves of tensile experiment for its angle-ply laminates. Under uniaxial tensile loading, the 3D orthotropic elastic-plastic FE analysis and microscopic moiré interferometry of interlaminar deformations are carried out for the [±25]S4 laminates. The quantitative local-filed experimental results of interlaminar shear strain and displacements at freeedge surface of the laminate are compared with corresponding numerical results of the orthotropic elastic-plastic FE model. It is indicated that the numerical tensile stressstrain curves of angle-ply laminates computed with 3D orthotropic elastic-plastic model are agree with experimental results. The numerical interlaminar displacement U and shear strain ?xz are also consistent with the experimental results obtained by moiré interferometry. It is expected the elastic-plastic interlaminar stresses and deformations analysis for the optimal design and application of AS4/PEEK laminates and its structures.

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

2010-06-01

265

Stress-induced structural changes in thermoplastic composites  

SciTech Connect

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.

Kitano, A.

1991-01-01

266

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

PubMed Central

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

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

2011-01-01

267

Dielectric characterization of PCL-based thermoplastic materials for microwave diagnostic and therapeutic applications.  

PubMed

We propose the use of a polycaprolactone (PCL)-based thermoplastic mesh as a tissue-immobilization interface for microwave imaging and microwave hyperthermia treatment. An investigation of the dielectric properties of two PCL-based thermoplastic materials in the frequency range of 0.5-3.5 GHz is presented. The frequency-dependent dielectric constant and effective conductivity of the PCL-based thermoplastics are characterized using measurements of microstrip transmission lines fabricated on substrates comprised of the thermoplastic meshes. We also examine the impact of the presence of a PCL-based thermoplastic mesh on microwave breast imaging. We use a numerical test bed comprised of a previously reported 3-D anatomically realistic breast phantom and a multi-frequency microwave inverse scattering algorithm. We demonstrate that the PCL-based thermoplastic material and the assumed biocompatible medium of vegetable oil are sufficiently well matched such that the PCL layer may be neglected by the imaging solution without sacrificing imaging quality. Our results suggest that PCL-based thermoplastics are promising materials as tissue immobilization structures for microwave diagnostic and therapeutic applications. PMID:21622068

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

2012-03-01

268

Polymer research at NASA Langley Research Center  

NASA Technical Reports Server (NTRS)

Polymer synthesis programs involve the development of Novel thermoplastics, pseudothermoplastics, and thermosets. These systems are prepared to elucidate structure-property relationships involving thermal capabilities, toughness, processability and environmental stability. Easily processable polyimides, solvent-resistant polysulfones and polyphenylquinoxalines, and tougher high and intermediate temperature polymers were developed. Characterization efforts included high pressure liquid chromatography methodology, the development of toughness tests for fiber reinforced composites, a study of electrical properties of metal ion filled polyimides, and a study of the mutagenicity of aromatic diamines. Also the mechanism of cure/degradation of experimental polymers was studied by rheology, mechanical behavior, separation techniques and spectroscopy. The degradative crosslinking of alkyl-containing polyimides, the separation and identification of crosslinked phenylquinoxalines, the rheological behavior of hot-melt polyimides, and the elucidation of the cure of norbornene endcapped imides were also studied.

St.clair, T. L.; Johnston, N. J.

1982-01-01

269

High performance thermoplastics: A review of neat resin and composite properties  

NASA Technical Reports Server (NTRS)

A review was made of the principal thermoplastics used to fabricate high performance composites. Neat resin tensile and fracture toughness properties, glass transition temperatures (Tg), crystalline melt temperatures (Tm) and approximate processing conditions are presented. Mechanical properties of carbon fiber composites made from many of these thermoplastics are given, including flexural, longitudinal tensile, transverse tensile and in-plane shear properties as well as short beam shear and compressive strengths and interlaminar fracture toughness. Attractive features and problems involved in the use of thermo-plastics as matrices for high performance composites are discussed.

Johnston, Norman J.; Hergenrother, Paul M.

1987-01-01

270

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

NASA Technical Reports Server (NTRS)

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.

Rogers, J. W.

1975-01-01

271

High-Temperature Shape Memory Polymers  

NASA Technical Reports Server (NTRS)

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

Yoonessi, Mitra; Weiss, Robert A.

2012-01-01

272

Thermally stable chromophores and polymers for ?(2) applications  

NASA Astrophysics Data System (ADS)

Due to the requirements for thermal stability in the fabrication and operation of electro-optic devices, the quest for suitable NLO chromophores and polymers involves more than the search for highly nonlinear materials. We describe here the preparation and characterization of aryl substituted azole derivatives as a class of thermally stable nonlinear chromophores and their incorporation into high temperature thermoplastics as a host-guest array. Criteria for predicting the thermal stability of NLO chromophores are discussed as are the polar order decay properties of various poled polymer systems as a function of temperature.

Miller, Robert D.; Betterton, K. M.; Burland, Donald M.; Lee, Victor Y.; Moylan, Christopher R.; Twieg, Robert J.; Walsh, C. A.; Volksen, Willi

1994-01-01

273

Study of Time-Dependent Properties of Thermoplastics  

NASA Astrophysics Data System (ADS)

Simple tests carried out with a common tension/compression testing machine are used to obtain timedependent properties of non-reinforced thermoplastics. These tests include ramp loadings as well as relaxation and creep tests. Two materials (PBT Celanex 2002-2 and POM Hostaform C9021, Ticona GmbH, Kelsterbach) were taken for the experiments. The experiments show that an adequate description of the long-term material properties can be obtained from the short-time tests, namely from tests with constant traverse speed L^.. Below a model for the time-dependent mechanical behavior is presented and fitted to the obtained measured data. For the evaluation of the fitting quality long-term tests are used. Especially creep and relaxation tests with ”jumps”, i.e. rapid change of loading, are important for this purpose.

Kolupaev, V. A.; Bolchoun, A.; Altenbach, H.

2010-06-01

274

Monitoring the resistance welding of thermoplastic composites through acoustic emission  

NASA Astrophysics Data System (ADS)

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.

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

275

Dye-doped thermoplastics for holographic data storage  

NASA Astrophysics Data System (ADS)

Holographic data storage materials based on a dye-doped thermoplastic that could find application in professional archival and consumer applications are described. The dye is selected from the class of o-nitrostilbenes, which irreversibly bleaches under exposure to light and shows high thermal stability before and after exposure. The reduction in concentration of the dye in the host after exposure induces refractive index variations over a wide range of wavelengths and extends well away from the dye absorption peak conforming to the Kramers-Kronig relationship. The materials are injection moldable into the standard disc format and have negligible shrinkage during data storage. Samples were produced using different dyes and various concentrations in a polycarbonate host and processed on professional CD/DVD equipment. The refractive index change is as high as 0.04, with a measured instantaneous sensitivity of 0.5 cm/J and M/# = 0.3.

Boden, Eugene P.; Dubois, Marc; Shi, Xiaolei; Lawrence, Brian; Erben, Christoph; Longley, Kathryn L.

2006-08-01

276

Superhydrophobic thermoplastic polyurethane films with transparent/fluorescent performance.  

PubMed

In this paper, we report a simple and versatile route for the fabrication of superhydrophobic thermoplastic polyurethane (TPU) films. The approach is based on octadecanamide (ODAA)-directed assembly of nanosilica/TPU/ODAA hybrid with a well-defined sheetlike microstructure. The superhydrophobic hybrid film shows a transparent property, and its water contact angle reaches as high as 163.5° without any further low surface energy treatment. In addition, the superhydrophobic TPU hybrid film with fluorescent properties is achieved by smartly introducing CdTe quantum dots, which will extend potential application of the film to optoelectronic areas. The resulting fluorescent surface produced in this system is stable and has a water contact angle of 172.3°. This assembly method to control surface structures represents an intriguing and valuable route to tune the surface properties of organic-inorganic hybrid films. PMID:21043449

Yang, Shengyang; Wang, Lifang; Wang, Cai-Feng; Chen, Li; Chen, Su

2010-12-01

277

Permittivity measurement of thermoplastic composites at elevated temperature.  

PubMed

The material properties of greatest importance in microwave processing of a dielectric are the complex relative permittivity epsilon = epsilon'-jepsilon", and the loss tangent, tan delta = epsilon"/epsilon'. This paper describes two convenient laboratory based methods to obtain epsilon', epsilon" and hence tan delta of fibre-reinforced thermoplastic (FRTP) composites. One method employs a microwave network analyzer in conjunction with a waveguide transmission technique, chosen because it provides the widest possible frequency range with high accuracy. The values of the dielectric constant and dielectric loss of glass fibre reinforced (33%) low density polyethylene, LDPE/GF (33%), polystyrene, PS/GF (33%), and Nylon 66/GF (33%), were obtained. Results are compared with those obtained by another method using a high-temperature dielectric probe. PMID:15040528

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

2001-01-01

278

Modeling Fatigue Damage in Long-Fiber Thermoplastics  

SciTech Connect

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.

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

2009-10-30

279

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

Microsoft Academic Search

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:

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

280

Development of bonding methods and energy absorption of sandwich panels for thermoplastic advanced composites.  

E-print Network

??Given their high strength-to-weight and stiffness-to-weight ratios, sandwich composites continue to be considered for automotive applications. Thermoplastic materials, while difficult to bond, have an increased… (more)

Haslam, Erik Bravant

2012-01-01

281

Thermal Degradation Effects on Consolidation and Bonding in the Thermoplastic Fiber-Placement Process.  

National Technical Information Service (NTIS)

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

B. K. Fink, J. W. Gillespie, N. B. Ersoy

2000-01-01

282

Thermal Edge-Effects Model for Automated Tape Placement of Thermoplastic Composites.  

National Technical Information Service (NTIS)

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 p...

R. C. Costen

2000-01-01

283

Effects of Repair Processing on the Mechanical Properties of Thermoplastic Matrix Composites.  

National Technical Information Service (NTIS)

Issues relating to the repair of thermoplastic matrix composite materials are investigated. The effects of rapid heating and cooling cycles, typical of most remelting repair processes, on the crystalline morphology and interlaminar fracture toughness of A...

S. V. Hoa, X. R. Xiao

1992-01-01

284

Interpenetrating polymer network approach to tougher and more microcracking resistant high temperature polymers. I. LaRC-RP40  

SciTech Connect

Interpenetrating polymer networks in the form of the LaRC-RP40 resin, prepared by the in situ polymerization of a thermosetting imide prepolymer and thermoplastic monomer reactants, are presently used to obtain toughness and microcracking resistance in a high-temperature polymer. Attention is presently given to the processing, physical, and mechanical properties, as well as the thermooxidative stability, of both the neat resin and the resin as a graphite fiber-reinforced matrix. Microcracking after thermal cycling was also tested. LaRC-RP40 exhibits significant resin fracture toughness improvements over the PMR-15 high-temperature matrix resin. 16 references.

Pater, R.H.; Morgan, C.D.

1988-10-01

285

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

E-print Network

PARAMETRIC WEAR TESTS FOR DRILLING IN THERMOPLASTIC FIBER COMPOSITES/METAL STACKS A Thesis by IOSIF HRISCU Submitted to the Office of Graduate Studies of Texas AkM University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE May 1991 Major Subject: Mechanical Engineering PARAMETRIC WEAR TESTS FOR DRILLING IN THERMOPLASTIC FIBER COMPOSITES/METAL STACKS A Thesis by IOSIF HRISCU Approved as to style and content by: Clarence L. gh, r (Chair...

Hriscu, Iosif

2012-06-07

286

Investigation of ignition of thermoplastics through the Hot Wire Ignition Test  

E-print Network

INVESTIGATION OF IGNITION OF THERMOPLASTICS THROUGH THE HOT WIRE IGNITION TEST A Thesis by LUIZ CLAUDIO BONILLA DE ARAUJO Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1998 Major Subject: Safety Engineering INVESTIGATION OF IGNITION OF THERMOPLASTICS THROUGH THE HOT WIRE IGNITION TEST A Thesis by LUIZ CLAUDIO BONILLA DE ARAUJO Submitted to Texas ARM University in partial...

De Araujo, Luiz Claudio Bonilla

2012-06-07

287

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

SciTech Connect

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.

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

288

Rapid Processing of Net-Shape Thermoplastic Planar-Random Composite Preforms  

Microsoft Academic Search

A novel thermoplastic composite preforming and moulding process is investigated to target cost issues in textile composite\\u000a processing associated with trim waste, and the limited mechanical properties of current bulk flow-moulding composites. The\\u000a thermoplastic programmable powdered preforming process (TP-P4) uses commingled glass and polypropylene yarns, which are cut to length before air assisted deposition onto a vacuum\\u000a screen, enabling local

S. T. Jespersen; F. Baudry; D. Schmäh; M. D. Wakeman; V. Michaud; P. Blanchard; R. E. Norris; J.-A. E. Månson

2009-01-01

289

A solid-state NMR investigation into microphase separation in polyurethane thermoplastic elastomers  

SciTech Connect

A combination of {sup 13}C-CP-MAS and static {sup 2}H-NMR techniques were used to study phase separation in polyurethane thermoplastic elastomers. The segmented polymers were prepared from hard segments comprised of 4,4{prime}-dicyclohexylmethane diisocyanate (DCHDI) chain extended with 1,4-butanediol, and soft segments of either poly(propylene glycol) or poly(butylene adipate). The DCHDI was prepared so as to contain different levels of the various geometric isomers, i.e., the cis,cis, cis,trans and trans,trans isomers, in order to monitor the influence of the trans,trans content on segmental mobility and phase separation. Lineshape analysis of static {sup 2}H-NMR spectra of samples selectively labelled in the chain extender indicate the trans,trans isomer constrains motion much more effectively than the other isomers of DCHDI at temperatures above the dynamic glass transition temperature of the soft phase and below the melting point of the hard domains. This is confirmed both by {sup 1}H-spin diffusion and t{sub 1{rho}} relaxation data. The data also indicate that the samples prepared with less trans-trans DCHDI have a much more significant interphase region than when DCHDI with a higher trans,trans content was employed, or that the higher trans-trans content allows for better hard domain formation. This insinuates that a relatively small amount of the trans,trans isomer of the DCHDI is more effective in allowing for the formation of physical cross-links than a larger amount of a statistical distribution of the diisocyanate, as corroborated by DSC and DMTA.

Meltzer, A.D.; Lantman, C.W.; Steppan, S.; Seneker, S.; Wehrle, B. [Miles Inc., Pittsburgh, PA (United States)

1993-12-31

290

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

NASA Astrophysics Data System (ADS)

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.

Warren, Paul B.

291

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

SciTech Connect

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

Furtado, C.A. [CDTN/CNEN, Belo Horizonte, MG (Brazil). Centro de Desenvolvimento da Tecnologia Nuclear] [CDTN/CNEN, Belo Horizonte, MG (Brazil). Centro de Desenvolvimento da Tecnologia Nuclear; Silva, G.G.; Machado, J.C.; Pimenta, M.A.; Silva, R.A. [UFMG/ICEx, Belo Horizonte, MG (Brazil)] [UFMG/ICEx, Belo Horizonte, MG (Brazil)

1999-08-26

292

Radiation curing of polymers. December 1986-December 1988 (Citations from the COMPENDEX data base). Report for December 1986-December 1988  

SciTech Connect

This bibliography contains citations concerning the radiation crosslinking of thermoplastic and thermosetting plastics and elastomers. Energy efficiency and performance of polymer curing by such radiation as ultraviolet, microwave, and infrared wavelengths are discussed relative to such materials as polymeric coatings, adhesives, elastomers, and epoxy resins. Hazards of radiation curing of polymers as well as applications of the electron-processed plastics are included. (This updated bibliography contains 176 citations, 62 of which are new entries to the previous edition.)

Not Available

1989-01-01

293

Coordination polymers  

Microsoft Academic Search

This paper is a review of the metal complex forming coordination polymers. A polymer–metal complex is composed of synthetic polymer and metal ions bound to the polymer ligand by a coordinate bond. A polymer ligand contains anchoring sites like nitrogen, oxygen or sulphur obtained either by the polymerization of monomer possessing the coordinating site or by a chemical reaction between

T. Kaliyappan; P. Kannan

2000-01-01

294

Flow properties of a series of experimental thermoplastic polymides  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

295

High-resolution ablation of amorphous polymers using CO2 laser irradiation  

NASA Astrophysics Data System (ADS)

Etching of various amorphous polymers by the application of CO2 laser radiation (10.6 ?m) is described. By passage of the radiation through a high-resolution mask in contact with the polymer surface, this ablation can produce images having submicron resolution and good edge acuity. The laser intensity required for ablation is compared for various thermoplastic and thermosetting polymers. Below the required level of intensity, no ablation is observed, but the laser irradiation can result in thermal crystallization. The energy necessary to induce ablation with infrared radiation is comparable to that required for UV decomposition.

Sonnenschein, Mark F.; Roland, C. Michael

1990-07-01

296

Self-Healing Polymer Networks  

NASA Astrophysics Data System (ADS)

Supramolecular chemistry teaches us to control non-covalent interactions between organic molecules, particularly through the use of optimized building blocks able to establish several hydrogen bonds in parallel. This discipline has emerged as a powerful tool in the design of new materials through the concept of supramolecular polymers. One of the fascinating aspects of such materials is the possibility of controlling the structure, adding functionalities, adjusting the macroscopic properties of and taking profit of the non-trivial dynamics associated to the reversibility of H-bond links. Applications of these compounds may include adhesives, coatings, rheology additives, high performance materials, etc. However, the synthesis of such polymers at the industrial scale still remains a challenge. Our first ambition is to design supramolecular polymers with original properties, the second ambition is to devise simple and environmentally friendly methods for their industrial production. In our endeavours to create novel supramolecular networks with rubbery elasticity, self-healing ability and as little as possible creep, the strategy to prolongate the relaxation time and in the same time, keep the system flexible was to synthesize rather than a single molecule, an assembly of randomly branched H-bonding oligomers. We propose a strategy to obtain through a facile one-pot synthesis a large variety of supramolecular materials that can behave as differently as associating low-viscosity liquids, semi-crystalline or amorphous thermoplastics, viscoelastic melts or self-healing rubbers.

Tournilhac, Francois

2012-02-01

297

Combustion of a Polymer (PMMA) Sphere in Microgravity  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

298

Comparison of piezoresistive monofilament polymer sensors.  

PubMed

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

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

2014-01-01

299

Thermoplastic Starch Films with Vegetable Oils of Brazilian Cerrado  

NASA Astrophysics Data System (ADS)

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.

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

2008-08-01

300

The pressure-flow characteristic of circular molding channels with a nonisothermal flow of thermoplastic polymers  

Microsoft Academic Search

The article contains results of a numerical investigation of the presure-flow characteristic of high-viscosity flows for different\\u000a rates of heat transfer with the environment. The effect of nonmonotonicity of the characteristic ?P(Vo) on the stability of operation of the die head of extrusion apparatus is discussed.

L. M. Ul’ev

1996-01-01

301

The pressure-flow characteristic of circular molding channels with a nonisothermal flow of thermoplastic polymers  

Microsoft Academic Search

The article contains results of a numerical investigation of the presure-flow characteristic of high-viscosity flows for different rates of heat transfer with the environment. The effect of nonmonotonicity of the characteristic DeltaP(Vo) on the stability of operation of the die head of extrusion apparatus is discussed.

L. M. Ul'Ev

1996-01-01

302

Theoretical investigations of continuous ultrasonic seam welding of thermoplastic polymers and fabrics  

Microsoft Academic Search

The article presents results of theoretical investigations of formation of continuous joint in contact area of flat surface of the radiator with rotating surface of the pressure roller. The recommendation on the choice of pressure roller parameters and optimal amplitude of ultrasonic vibrations and broach speed for materials different in properties and thickness were developed on the basis of analysis

Vladimir N. Khmelev; Aleksey N. Slivin; Andrey V. Lehr; Aleksey D. Abramov

2010-01-01

303

Planar antenna arrays at 60 GHz realized on a new thermoplastic polymer substrate  

Microsoft Academic Search

Electromagnetic waves are severely attenuated at the 60 GHz band and therefore high gain antennas are mandatory to assure medium as well as long distance communication. Efficient antennas like dish and waveguide antennas might be used for outdoor applications, however, their big size and\\/or high cost is an obstacle for cost-efficient and low profile indoor systems. The investigation of highly

Mahmoud Al Henawy; Martin Schneider

2010-01-01

304

Dispersion and Characterization of Nickel Nanostrands in Thermoset and Thermoplastic Polymers  

E-print Network

fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Zoubeida Ounaies Committee Members, Ramesh Talreja Hung-Jue Sue Head of Department, Dimitris Lagoudas December 2011 Major Subject... fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Zoubeida Ounaies Committee Members, Ramesh Talreja Hung-Jue Sue Head of Department, Dimitris Lagoudas December 2011 Major Subject...

Whalen, Casey Allen

2012-02-14

305

Thermoplastic elastomers derived from menthide and tulipalin A.  

PubMed

Renewable ABA triblock copolymers were prepared by sequential polymerization of the plant-based monomers menthide and ?-methylene-?-butyrolactone (MBL or tulipalin A). Ring-opening transesterification polymerization of menthide using diethylene glycol as an initiator gave ?,?-dihydroxy poly(menthide) (HO-PM-OH), which was converted to ?,?-dibromo end-functionalized poly(menthide) (Br-PM-Br) by esterification with excess 2-bromoisobutyryl bromide. The resulting 100 kg mol(-1) Br-PM-Br macroinitiator was used for the atom transfer radical polymerization of MBL. Four poly(?-methylene-?-butyrolactone)-b-poly(menthide)-b-poly(?-methylene-?-butyrolactone) (PMBL-PM-PMBL) triblock copolymers were prepared containing 6-20 wt % PMBL, as determined by NMR spectroscopy. Small-angle X-ray scattering, differential scanning calorimetry, and atomic force microscopy experiments supported microphase separation in the four samples. The mechanical behavior of the triblocks was investigated by tensile and elastic recovery experiments. The tensile properties at both ambient and elevated temperature show that these materials are useful candidates for high-performance and renewable thermoplastic elastomer materials. PMID:23062206

Shin, Jihoon; Lee, Youngmin; Tolman, William B; Hillmyer, Marc A

2012-11-12

306

Hydrolytic degradation behavior of a renewable thermoplastic elastomer.  

PubMed

The hydrolytic degradation of polylactide-polymenthide-polylactide triblock copolymers (37 degrees C, pH 7.4) is compared to that of the component homopolymers. In addition to mass loss and water uptake measurements, size exclusion chromatography (SEC), 1H NMR spectroscopy, differential scanning calorimetry (DSC), and mechanical testing were used to monitor property changes during degradation. The rate of copolymer degradation was significantly influenced by the molecular weight of the polylactide end blocks. Mass loss of the polylactide homopolymer and the copolymer samples was observed once a decrease in the total molecular weight of the samples of 20% occurred. 1H NMR spectroscopy and DSC analysis of the copolymers during degradation revealed that the released oligomers contained mostly polylactide. After initial water uptake in which the mechanical properties were compromised to an extent, the Young's modulus and elongation at break of the biorenewable copolymers remained relatively unperturbed for up to 16 weeks, with significant retention of thermoplastic elastomeric properties for up to 21 weeks. PMID:19159199

Wanamaker, Carolyn L; Tolman, William B; Hillmyer, Marc A

2009-02-01

307

Thermoplastic starch/wood composites: interfacial interactions and functional properties.  

PubMed

Thermoplastic starch (TPS)/wood composites were prepared from starch plasticized with 36 wt% glycerol. The components were homogenized by dry-blending, extruded and injection molded to tensile bars. Tensile properties, structure, deformation, water adsorption and shrinkage were determined as a function of wood content, which changed between 0 and 40 vol% in 7 steps. The modification of TPS with wood particles improves several properties considerably. Stiffness and strength increases, and the effect is stronger for fibers with larger aspect ratio. Wood fibers reinforce TPS considerably due to poor matrix properties and strong interfacial interactions, the latter resulting in the decreased mobility of starch molecules and in the fracture of large wood particles during deformation. Strong interfacial adhesion leads to smaller water absorption than predicted from additivity, but water uptake remains relatively large even in the presence of wood particles. The shrinkage of injection molded TPS parts is very large, around 10%, and dimensional changes occur on a very long timescale of several hundred hours. Shrinkage decreases to a low level already at 15-20 vol% wood content rendering the composites good dimensional stability. PMID:24507352

Müller, Péter; Renner, Károly; Móczó, János; Fekete, Erika; Pukánszky, Béla

2014-02-15

308

Potential for advanced thermoplastic composites in space systems  

SciTech Connect

This paper provides rational for incorporating graphite/thermoplastic into future Strategic Defense Initiative space systems. Graphite/PEEK is compared with the best available graphite/epoxy materials, which today are graphite/1962 produced by Amoco and graphite/934 produced by Fiberite. A first-order comparison reveals similar performance between these classes of materials with respect to maximum stiffness, minimum gage, maximum damping and threat hardness. There are significant differences in the behavior of graphite/polyether ether ketone and graphite/epoxy with respect to the following characteristics: water absorption, condensible-volatile contents, space-environment effects, dimensional stability, weight-savings options, joining alternatives, and production costs. A comparison is also made between organic composites, such as graphite/PEEK, with other spacecraft structural materials, such as aluminum and beryllium (which are commonly used today). The differing requirements for each spacecraft component will determine which of these material options is best suited for the particular structural application. 35 refs., 8 figs., 2 tabs.

Garvey, R.E.

1990-01-01

309

Nanoembossed polymer substrates for biomedical surface interaction studies.  

PubMed

Biomedical devices are moving towards the incorporation of nanostructures to investigate the interactions of biological species with such topological surfaces found in nature. Good optical transparency and sealing properties, low fabrication cost, fast design realization times, and biocompatibility make polymers excellent candidates for the production of surfaces containing such nanometric structures. In this work, a method for the production of nanostructures in free-standing sheets of different thermoplastic polymers is presented, with a view to using these substrates in biomedical cell-surface applications where optical microscopy techniques are required. The process conditions for the production of these structures in poly(methyl methacrylate), poly(ethylene naphthalate), poly(lactic acid), poly(styrene), and poly(ethyl ether ketone) are given. The fabrication method used is based on a modified nanoimprint lithography (NIL) technique using silicon based moulds, fabricated via reactive ion etching or focused ion beam lithography, to emboss nanostructures into the surface of the biologically compatible thermoplastic polymers. The method presented here is designed to faithfully replicate the nanostructures in the mould while maximising the mould lifetime. Examples of polymer replicas with nanostructures of different topographies are presented in poly(methyl methacrylate), including nanostructures for use in cell-surface interactions and nanostructure-containing microfluidic devices. PMID:18283849

Mills, Christopher A; Martinez, Elena; Errachid, Abdelhamid; Engel, Elisabeth; Funes, Miriam; Moormann, Christian; Wahlbrink, Thorsten; Gomila, Gabriel; Planell, Josep; Samitier, Josep

2007-12-01

310

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.

2014-09-10

311

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

Microsoft Academic Search

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

Sok Won Kim; Seungmin Oh; Kyuse Lee

2007-01-01

312

Influence of the addition of thermoplastic preformed particles on the properties of an epoxy\\/anhydride network  

Microsoft Academic Search

An anhydride\\/epoxy system is modified by the introduction of thermoplastic microparticles (ORGASOL®). The influence of the presence of polyamide (PA) particles is evaluated on the reactivity of the epoxy\\/anhydride system below the melting temperature of the thermoplastic. Networks containing various amounts of polyamide are prepared using a cure schedule in order to keep the PA particles below their melting point.

C. Girodet; E. Espuche; H. Sautereau; B. Chabert; R. Ganga; E. Valot

1996-01-01

313

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

SciTech Connect

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.

Yoon Taeho.

1991-01-01

314

Self-Healing Polymers and Composites  

NASA Astrophysics Data System (ADS)

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.

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

2010-08-01

315

Fabrication of a Polymer Micro Needle Array by Mask-Dragging X-Ray Lithography and Alignment X-Ray Lithography  

Microsoft Academic Search

Polymer materials such as transparent thermoplastic poly(methyl methacrylate) (PMMA) have been of great interest in the research and development of integrated circuits and micro-electromechanical systems due to their relatively low cost and easy process. We fabricated PMMA-based polymer hollow microneedle arrays by mask-dragging and aligning x-ray lithography. Techniques for 3D micromachining by direct lithography using x-rays are developed. These techniques

Yi-Gui Li; Chun-Sheng Yang; Jing-Quan Liu; Susumu Sugiyama

2011-01-01

316

Radiation curing of polymers. December 1983-November 1986 (citations from the Engineering Index data base). Report for December 1983-November 1986  

SciTech Connect

This bibliography contains citations concerning the radiation crosslinking of thermoplastic and thermosetting plastics and elastomers. Energy efficiency and performance of polymer curing by such radiation as ultraviolet, microwave and infrared wavelengths are discussed relative to such materials as polymeric coatings, adhesives, elastomers, and epoxy resins. Hazards of radiation curing of polymers as well as applications of the electron processed plastics are included. (This updated bibliography contains 324 citations, none of which are new entries to the previous edition.)

Not Available

1987-12-01

317

Radiation curing of polymers. December 1986-December 1987 (citations from the Engineering Index data base). Report for December 1986-December 1987  

SciTech Connect

This bibliography contains citations concerning the radiation crosslinking of thermoplastic and thermosetting plastics and elastomers. Energy efficiency and performance of polymer curing by such radiation as ultraviolet, microwave and infrared wavelengths are discussed relative to such materials as polymeric coatings, adhesives, elastomers, and epoxy resins. Hazards of radiation curing of polymers as well as applications of the electron processed plastics are included. (This updated bibliography contains 128 citations, all of which are new entries to the previous edition.)

Not Available

1987-12-01

318

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

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

319

Design considerations for manufacturing carbon-fiber thermoplastic composites using microwave heating  

SciTech Connect

In an effort to lower the cost of manufacturing carbon-fiber thermoplastic composites, McDonnell Douglas Aerospace is investigating automated tape and fiber placement manufacturing methods. In these methods, structures are fabricated one ply at a time by applying heat to raise the bond line to the softening point of the thermoplastic and applying pressure to consolidate the ply to the structure being fabricated. Infrared, microwave, radio frequency and laser methods are being considered to quickly heat the thermoplastic resin to its consolidation temperature. The penetration of the heating power is different in each of these methods. We are currently conducting studies to determine if microwave heating has significant advantages over alternate heating methods and if so, how it should be incorporated into an actual manufacturing process. This paper describes the results of our studies concerning how the power density and penetration depth affect the manufacturing process.

Lind, A.C.; Wear, F.C. [McDonnell Douglas Aerospace, St. Louis, MO (United States)

1995-12-01

320

The process and microstructure modeling of long-fiber thermoplastic composites  

NASA Astrophysics Data System (ADS)

Interest in thermoplastic matrix composites has increased in recent years due to several advantages of these materials, including high volume process ability, recyclability, superior damage tolerance and fracture toughness, and ability to produce complex shapes. Among thermoplastic composites, long-fiber thermoplastics (LFTs) are finding increased use in the automotive and transportation sector. Predictive process and material characterization tools are much needed in industry to minimize expensive tooling/process trials and to improve the design avenues for parts produced using LFTs. The current work focuses on finite element simulation of LFT materials for two scenarios: first, process modeling of LFTs to evaluate the flow of fiber-filled viscous charge during compression molding and the resulting fiber orientation prediction and, second, modulus prediction of LFT materials accounting for fiber orientation and distribution. Together these tools provide insight into the process and performance characteristics of LFT materials.

Vaidya, U. K.; Chawla, K. K.; Balaji Thattaiparthasarthy, K.; Goel, A.

2008-04-01

321

Characterization of glass-filled engineering thermoplastic composites  

SciTech Connect

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.

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

1983-01-01

322

Through-transmission ultrasonics for on-line sensing and control of thermoplastic fusion bonding processes  

NASA Astrophysics Data System (ADS)

The focus of this work is to develop Through-Transmission Ultrasonics (TTU) as a process monitoring technique for non-intrusive, on-line control of thermoplastic fusion bonding. A model is developed to predict the TTU amplitude of a fusion bond by joining the theory of ultrasonic wave propagation through multilayered structures with a model for the evolution of intimate contact at the material interfaces. A new approach, the Averaged Transmission Model (ATM), is developed for treating the effects of imperfect contact at the bond interface. This approach is based upon statistical averaging of the transmission coefficients for the various sound paths between source and receiver. The extension of the model for an arbitrary number of rough interfaces is derived. The temperature dependence of sound velocity and ultrasonic attenuation of the materials are important properties. Experimental techniques based on both pulse-echo and laser ultrasonics in through-transmission mode were developed to characterize these properties at temperatures approaching 330°C. Validation of the ATM was accomplished by comparison of model predictions for PEEK polymer and PEEK/AS4 composites to data from resistance welding experiments. These studies were conducted in three phases. Phase one explored the TTU response to temperature at a fixed degree of intimate contact. Model results correlated well to experimental measurements. In phase two, interface structure was controlled to determine the effect of variable contact on the TTU amplitude at a fixed temperature. Model predictions were compared to TTU measurements for both single and dual interface cases with favorable results. In the phase three, model predictions were compared to results of a post-process TTU inspection of isothermally processed resistance welds. Model results were in agreement with experimental over a wide range of processing times. Hertzian contact theory was used to modify the initial degree of contact resulting from consolidation pressure. Strength development in the third-phase welds was determined to be intimate contact controlled, establishing a direct relationship between TTU amplitudes and strength. A near-linear relationship was found, demonstrating the potential for on-line, non-intrusive monitoring of weld strength.

Tackitt, Kirk David

323

Preparation and characterization of siloxane-containing thermoplastic polyimides  

NASA Technical Reports Server (NTRS)

Copolyimides and homopolyimides of bis(gamma-aminopropyl)tetramethyldisiloxane and 3,3'-diaminobenzophenone have been prepared with benzophenonetetracarboxylic dianhydride. The properties of the copolyimides were compared with those of the homopolyimides to assess the effect of incorporation of siloxane groups in the backbone. Applications of the polymers as adhesives and mouldings are discussed.

Maudgal, S.; St Clair, T. L.

1984-01-01

324

Space environmental effects on polymer composites: Research needs and opportunities  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

325

Development of thermoplastic composite tubes for large deformation  

NASA Astrophysics Data System (ADS)

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.

Derisi, Bijan

326

Fatigue and environmental behavior of long fiber thermoplastic (LFT) composites  

NASA Astrophysics Data System (ADS)

In the present work we have characterized the mechanical behavior of long fiber thermoplastic (LFT) composites (21% E-glass fiber/polypropylene) under different conditions. We start by comparing the elastic modulus of LFT predicted by a microstructure-based approach called Object Oriented Finite (OOF) element method, and compare the result with prediction from various models commonly used in the literature and the experimental value. The predictions from the models used currently in the literature did not agree well with the experimental value due to the assumptions inherent in the models. The prediction by OOF was the closest to the experimental value because of the microstructure based approach which takes into account the fiber distribution and orientation during the finite element calculation. This was followed by characterization of fatigue behavior of LFT. Samples tested along longitudinal direction showed a higher fatigue life than the transverse samples because of the preferred orientation of the fibers along the longitudinal direction developed during the processing of LFT by extrusion-compression molding process. Fatigue life decreased with increase in frequency. Hysteretic energy loss and temperature rise were measured; they depended on the stress amplitude as well as the cyclic frequency. LFT composite showed a lower temperature rise compared to neat PP because LFT has higher thermal conductivity than neat PP and thus faster heat dissipation to the surroundings occur. The hysteretic heating also led to decrease in the modulus of LFT as a function of number of cycles. The last part of the work was to study the effect of ultraviolet (UV) exposure on the microstructure and mechanical properties of LFT. Microscopic observations revealed that the damage due to UV was confined only to the surface region in the form of surface cracking and exposure of fibers to the surface in the case of LFT. FTIR and nanoindentation results showed that there was a large increase in the crystallinity and local modulus of the surface layer due to UV exposure. The change in crystallinity and modulus of the surface layer occurs by chemicrystallization wherein the broken, smaller chains due to UV radiation rearrange into more crystalline form. This increase in crystallinity causes increase in the modulus of surface layer and results in cracking of the surface because tensile residual stresses are generated in the surface layer due to the change in crystallinity. The overall modulus of the LFT, however, decreased with increasing UV exposure time due to the formation of surface cracks.

Goel, Ashutosh

327

Storage battery with thermoplastic casing having internal members for immobilizing the battery plates  

Microsoft Academic Search

Downwardly extending members are molded on the inside of a synthetic resin battery case cover and bear against the bridging members of battery plate assemblies or upward bulges of the battery plates to hold the latter vertically in place. The downwardly extending thermoplastic members may be heat-softened at their ends at the time the cover is fused onto the rest

M. Attinger; W. Eisenacher; F. Fraubose; L. Makkens; G. Niemann

1980-01-01

328

Reduction of infra-red heating cycle time in processing of thermoplastic composites using computer modelling  

Microsoft Academic Search

This paper deals with increasing the speed of the infra-red (IR) heating cycle in the processing of thermoplastic composites. A constraint on the heating process is that all parts of the material must be within the recommended processing temperature range before forming can start. A mathematical model is used to predict the transient temperature distribution through the thickness of flat

G. J. Sweeney; P. F. Monaghan; M. T. Brogan; S. F. Cassidy

1995-01-01

329

Multichannel and repeatable self-healing of mechanical enhanced graphene-thermoplastic polyurethane composites.  

PubMed

A novel self-healing material, which was fabricated using few-layered graphene (FG) and thermoplastic polyurethane (TPU) via a facile method, not only exhibits a mechanical enhanced property, but also can be repeatedly healed by various methods including infrared (IR) light, electricity and electromagnetic wave with healing efficiencies higher than 98%. PMID:23417742

Huang, Lu; Yi, Ningbo; Wu, Yingpeng; Zhang, Yi; Zhang, Qian; Huang, Yi; Ma, Yanfeng; Chen, Yongsheng

2013-04-18

330

Microwave absorption properties of a conductive thermoplastic blend based on polyaniline  

Microsoft Academic Search

Summary Conductive thermoplastic blends of polystyrene and polyaniline doped with dodecylbenzene sulfonic acid, DBSA and polystyrene sulfonic acid were prepared in an internal mixer. We used a block copolymer of styrene and butadiene as compatibilizer. Different formulations were tested according to a statistical response surface method. The electrical conductivity and the microwave radiation absorbing properties of the blends were evaluated.

Cristiane Reis Martins; Roselena Faez; Mirabel Cerqueira Rezende; Marco-A. De Paoli

2004-01-01

331

Physico-Technological Peculiarities of Forming of Radioabsorbing Materials Based on Composite Thermoplastics  

Microsoft Academic Search

Proceeding from the theoretical notions on the mechanisms of interactions between the object and electromagnetic radiation a physical model of a radio absorbing material (RAM) has been developed based on composite thermoplastics. Novel sheet, profile and fibrous non-woven RAM have been manufactured by the original techniques. Radiophysical characteristics and the scattering cross-section of the materials have been estimated in the

V. A. Bannyi

2006-01-01

332

Radioabsorbing Composite Materials Based on Thermoplastics: Production Technology and Structural Optimization Principles  

Microsoft Academic Search

Novel sheet, profile and fibrous nonwoven radioabsorbing materials (RAM) based on thermoplastic composites have been manufactured by the original techniques. The ability of the materials to absorb electromagnetic radiation of super high frequency has been estimated. Formulation, dimensional and structural characteristics of RAM have been optimized by the criterion of high radio absorption within 2?27 GHz frequency range. RAM under

Victor Bannyi; Anna Makarevich; Leonid Pinchuk

2003-01-01

333

Radioabsorbing composite materials based on thermoplastics: production technology and structural optimization principles  

Microsoft Academic Search

Novel sheet, profile and fibrous nonwoven radioabsorbing materials (RAM) based on thermoplastic composites have been manufactured by the original techniques. The ability of the materials to absorb electromagnetic radiation of super high frequency has been estimated. Formulation, dimensional and structural characteristics of RAM have been optimized by the criterion of high radio absorption within 2÷27 GHz frequency range. RAM under

Victor Bannyi; Anna Makarevich; L. Pinchuk

2003-01-01

334

Synthesis of thermoplastic polyurethanes and polyurethane nanocomposites under chaotic mixing conditions  

Microsoft Academic Search

The self-similar mixing microstructures generated in chaotic mixing of prepolymer and chain extender were utilized to augment conversion and molecular weight in the synthesis of thermoplastic polyurethanes (TPU) and polyurethane nanocomposites. The values of time scales of mixing and chemical reaction were varied so as to obtain the best possible product. The chaotic mixing parameter (theta), catalyst concentration, and chemical

Changdo Jung

2005-01-01

335

Economic and logistical modeling for regional processing and recovery of engineering thermoplastics  

Microsoft Academic Search

The economics of processing and recovering engineering thermoplastics from electronic products is not well understood. This is in part due to uncertainty as to the optimum system for collection and processing, and the ongoing challenges in consolidation, identification and sorting of plastics. This paper presents the results from the development of an economics and logistics model for a regional resin

Cynthia F. Murphy; Patricia S. Dillon; G. E. Pitts

2001-01-01

336

Properties of thermoplastic composites with cotton and guayule biomass residues as fiber fillers  

Microsoft Academic Search

This study was conducted to evaluate the suitability of using residual plant fibers from agricultural waste streams as reinforcement in thermoplastic composites. Three groups of plant fibers evaluated included cotton burrs, sticks and linters from cotton gin waste (CGW), guayule whole plant, and guayule bagasse. The plant fibers were characterized for physical (bulk density and particle size distribution) and chemical

Sreekala G. Bajwa; Dilpreet S. Bajwa; Greg Holt; Terry Coffelt; Francis Nakayama

2011-01-01

337

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

Microsoft Academic Search

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

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

2011-01-01

338

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

Microsoft Academic Search

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

H. Nouri; F. Meraghni; P. Lory

2009-01-01

339

Prediction of tensile yield strength of rigid inorganic particulate filled thermoplastic composites  

Microsoft Academic Search

Advances in the study of the tensile yield strength of rigid inorganic particulate filled thermoplastic composites have been reviewed and brief comments on the existing expressions for predicting it have been made in the present paper. The main factors affecting the yield strength of such composites are: (i)the interfacial adhesion between the fillers and the matrix; (ii)the shape, size and

J. Z. Liang; R. K. Y. Li

1998-01-01

340

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

Microsoft Academic Search

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

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

341

The use of rivets for electrical resistance measurement on carbon fibre-reinforced thermoplastics  

Microsoft Academic Search

The use of fibre-reinforced thermoplastics, for example in the aeronautical industry, is increasing rapidly. Therefore, there is an increasing need for in situ monitoring tools, which preferably have limited influence on the behaviour of the material and which are easy to use. Furthermore, in the aeronautical industry composites are very often attached with rivets. In this study, the possibility of

I. DeBaere; W. Van Paepegem; J. Degrieck

2007-01-01

342

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

NASA Technical Reports Server (NTRS)

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

Clarke, A. E., Jr.

1964-01-01

343

Thermoplastic elastomers based on polypropylene\\/natural rubber and polypropylene\\/recycle rubber blends  

Microsoft Academic Search

Fine rubber powder obtained from the sanding process of polishing rubber balls and artificial eggs (recycled rubber, RR) was used to prepare polypropylene (PP)\\/RR blends, a thermoplastic elastomer using different RR content. A similar series of blends using natural rubber, SMR L (NR) was also prepared. The results indicated that at a similar rubber content, PP\\/RR blends have higher, tensile

H Ismail; Suryadiansyah

2002-01-01

344

LASER BEAM WELDING OF THERMOPLASTICS PARAMETER INFLUENCE ON WELD SEAM QUALITY - EXPERIMENTS AND MODELING  

Microsoft Academic Search

Laser beam welding of thermoplastics offers process technical advantages due to contact-less energy input, which is spatially (?100 µm) and timely (? ms) very well defined. Different process strategies are possible leading to flexibility, product adapted irradiation, short process times and high quality seams, while avoiding mechanical stress and thermal load on the joining partners. Meanwhile, laser beam welding of

Ulrich-Andreas Russek; Mirko Aden; Jens Poehler; Andre Palmen; Henrik Staub

345

Mechanical Properties of Thermoplastic Polyurethanes Laminated Glass Treated by Acid Etching Combined with Cold Plasma  

NASA Astrophysics Data System (ADS)

To overcome the problem of interlaminar delamination of thermoplastic polyurethane laminated glass, silicate glass was etched with hydrofluoric acid and thermoplastic polyurethane was then treated with cold plasma. Compared with the untreated samples, the interlaminar shear strength of acid etching samples, cold plasma-treated samples and acid etching combined with cold plasma-treated samples increased by 97%, 84% and 341%, respectively. Acid etching combined with cold plasma-treated samples exhibited a higher flexural strength and strain as compared with the untreated samples. The impact energy of acid etching samples, cold plasma-treated samples and acid etching combined with cold plasma-treated samples increased by 8.7%, 8.1% and 11.6%, respectively, in comparison with the untreated samples. FT-IR analysis showed that a large number of –C=O, –CO–N and –CO–O–C– groups appeared on the surface of cold plasma-treated thermoplastic polyurethane, which resulted in the formation of hydrogen bonds. SEM results showed that some pittings formed on the surface of the silicate glass treated by acid etching, which resulted in the formation of a three-dimensional interface structure between the silicate glass and polyurethane. Hydrogen bonds combined with the three-dimensional interface between silicate glass and polyurethanes co-improved the mechanical properties of thermoplastic polyurethanes laminated glass.

Li, Xibao; Lu, Jinshan; Luo, Junming; Zhang, Jianjun; Ou, Junfei; Xu, Haitao

2014-10-01

346

Preparation and properties of starch thermoplastics modified with waterborne polyurethane from renewable resources  

Microsoft Academic Search

A waterborne polyurethane (PU) aqueous dispersion was synthesized from castor oil, and blended with thermoplastic starch (TPS) to obtain a novel biodegradable plastic with improved physical properties. The effect of PU content on the morphology, miscibility and physical properties of the resulting blends was well investigated by scanning electron microscopy, differential scanning calorimetry, dynamic mechanical thermal analysis and measurements of

Yongshang Lu; Lan Tighzert; Patrice Dole; Damien Erre

2005-01-01

347

Preparation and characterization of coaxial electrospun thermoplastic polyurethane\\/collagen compound nanofibers for tissue engineering applications  

Microsoft Academic Search

Collagen functionalized thermoplastic polyurethane nanofibers (TPU\\/collagen) were successfully produced by coaxial electrospinning technique with a goal to develop biomedical scaffold. A series of tests were conducted to characterize the compound nanofiber and its membrane in this study. Surface morphology and interior structure of the ultrafine fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force

Rui Chen; Chen Huang; Qinfei Ke; Chuanglong He; Hongsheng Wang; Xiumei Mo

2010-01-01

348

Stress corrosion crack propagation in glass fibre reinforced\\/thermoplastic PET  

Microsoft Academic Search

This study covers results of stress rupture tests obtained with compact tension specimens of a glass fibre\\/thermoplastic matrix composite in chemical environments at room temperature. The corrosive media used were various acidic solutions. All the tests indicate a deterioration of the crack resistances of the materials to a greater or lesser extent, under environmental attack, i.e. cracks can propagate faster

Klaus Friedrich

1981-01-01

349

Surface friction effects related to pressforming of continuous fibre thermoplastic composites  

Microsoft Academic Search

In the pressforming of thermoplastic composite sheet, the heated laminate is rapidly formed into a mould. The moulding force is transmitted using either matched metal dies or by a rubber pad\\/metal mould combination. Friction must occur between the metal or rubber mould surface and the heated composite as the laminate moves across the tool surface until it is fully formed.

Adrian M. Murtagh; John J. Lennon; Patrick J. Mallon

1995-01-01

350

Experiments on compression moulding and pultrusion of thermoplastic powder impregnated towpregs  

Microsoft Academic Search

Powder impregnation techniques have been developed to increase design and manufacturing flexibility with thermoplastic composites. The effect of pressure, temperature, mould closing rate and time on the consolidation of poly(ether ketone ketone) (PEKK) powder impregnated glass fibre towpregs in compression moulding were studied. A design of experiments approach was used. Isothermal pultrusion experiments using nylon 11 and PEKK powder impregnated

Karthik Ramani; Harshad Borgaonkar; Chris Hoyle

1995-01-01

351

Effect of Water Immersion on Fiber/Matrix Adhesion in Thermoplastic Composites.  

National Technical Information Service (NTIS)

Continuous fiber reinforced thermoplastics were tested for the effect of water immersion on fiber/matrix adhesion. The materials evaluated were E/PPS, AS4/PPS, E/J2, AS4/J2, S2/PEEK, AS4/PEEK, S2/PEKK, AS4/PEKK, and S2/VECTRA. These materials were tested ...

T. Juska

1993-01-01

352

Characterization of fatigue behavior of long fiber reinforced thermoplastic (LFT) composites  

Microsoft Academic Search

Fatigue behavior of long fiber reinforced thermoplastic composites (polypropylene\\/20 vol.% E-glass fiber) is presented in terms of stress – number of cycles to failure curves. Samples tested along longitudinal direction showed a higher fatigue life than the transverse samples which can be explained by the preferential orientation of the fibers along the longitudinal direction developed during the processing. Fatigue life decreased

A. Goel; K. K. Chawla; U. K. Vaidya; N. Chawla; M. Koopman

2009-01-01

353

Fabrication of polymer microfluidic systems by hot embossing and laser ablation.  

PubMed

Fabrication of microfluidic channels in common commercially available thermoplastic materials can be easily accomplished using hot embossing or ultraviolet (UV) laser ablation. Hot embossing involves replication of a microfluidic network in a polymer substrate from a stamp (or template) fabricated in silicon or metal. UV laser ablation is performed by either exposing the polymer substrate through a mask or by using a laser direct-write process. The resulting polymer microfluidic channels are most often sealed with another polymer piece using thermal bonding or solvent bonding to complete the fabrication procedure. Unlike their silicon and glass counterparts, polymer microfluidic systems can be fabricated by these methods in less than 1 h, making the materials attractive for both research prototyping and commercialization. PMID:16790865

Locascio, Laurie E; Ross, David J; Howell, Peter B; Gaitan, Michael

2006-01-01

354

The radiation induced degradation of polymers  

NASA Astrophysics Data System (ADS)

A compilation was made of all data about the radiation stability of thermoplastic polymeric materials, published in the literature up to the end of 1985. From those experiments in which the irradiation was carried out in air half value doses (elongation) ( = hvd) as a measure of radiation stability were extracted and compared on the basis of the chemical structure of the polymers, the chemical composition of the materials under test and the dose rate, respectively. The first result is that our knowledge of the radiation stability of polymers, if irradiated in air, is still very incomplete. On the other hand enough data were found for some polymers, to see that there is a region at low dose rates where the half value dose De increases with the dose rate D? according to the equation De = De1 · D? n. This seems to be the normal behavior. Values for the hvd at 1 Gy/h (in air) were found to lie between 1 and 500 kGy (with PTFE and PS at the respective ends of the scale), whereas n varied only between 0.1 and 0.4. The range of validity of the equation and the magnitude of the coefficients strongly depend on the chemical nature of the polymer and also on the kind and amount of the additives used. At dose rates in the neighborhood of 10 5 Gy/h the influence of the dose rate (and the atmosphere) disappears.

Wilski, Hans

355

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

SciTech Connect

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

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

2009-06-15

356

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

PubMed

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

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

2009-06-01

357

Polymer adsorption  

NASA Astrophysics Data System (ADS)

The aim of this talk is to review Pierre-Gilles deGennes' work on polymer adsorption and the impact that it has now in our understanding of this problem. We will first present the self-consistent mean-field theory and its applications to adsorption and depletion. De Gennes most important contribution is probably the derivation of the self-similar power law density profile for adsorbed polymer layers that we will present next, emphasizing the differences between the tail sections and the loop sections of the adsorbed polymers. We will then discuss the kinetics of polymer adsorption and the penetration of a new polymer chain in an adsobed layer that DeGennes described very elegantly in analogy with a quantum tunneling problem. Finally, we will discuss the role of polymer adsorption for colloid stabilization.

Joanny, Jean-Francois

2008-03-01

358

Natural Polymers  

NSDL National Science Digital Library

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

Teegarden, David

2004-01-01

359

Polymer Electrolytes  

NASA Astrophysics Data System (ADS)

This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

Hallinan, Daniel T.; Balsara, Nitash P.

2013-07-01

360

Polymer carpets.  

PubMed

The fabrication of defined polymer objects of reduced dimensions such as polymer-coated nanoparticles (zero-dimensional (0D)), cylindrical brushes (1D), and polymer membranes (2D), is currently the subject of intense research. In particular, ultrathin polymer membranes with high aspect ratios are being discussed as novel materials for miniaturized sensors because they would provide extraordinary sensitivity and dynamic range when sufficient mechanical stability can be combined with flexibility and chemical functionality. Unlike current approaches that rely on crosslinking of polymer layers for stabilization, this report presents the preparation of a new class of polymer material, so-called "polymer carpets," a freestanding polymer brush grown by surface-initiated polymerization on a crosslinked 1-nm-thick monolayer. The solid-supported, as well as freestanding, polymer carpets are found to be mechanically robust and to react instantaneously and reversibly to external stimuli by buckling. The carpet mechanics and the dramatic changes of the film properties (optical, wetting) upon chemical stimuli are investigated in detail as they allow the development of completely new integrated micro-/nanotechnology devices. PMID:20635346

Amin, Ihsan; Steenackers, Marin; Zhang, Ning; Beyer, André; Zhang, Xianghui; Pirzer, Tobias; Hugel, Thorsten; Jordan, Rainer; Gölzhäuser, Armin

2010-08-01

361

Polymer Bulletin ISSN 0170-0839  

E-print Network

.1007/s00289-011-0571-3 Strong thermoplastic elastomers created using nickel nanopowder Witold Brostow it is not made publicly available until 12 months after publication. #12;ORIGINAL PAPER Strong thermoplastic) to a thermoplastic elastomer (TPE) will make TPE properties better for demanding applications. We have found that Ni

North Texas, University of

362

Clinical application of removable partial dentures using thermoplastic resin. Part II: Material properties and clinical features of non-metal clasp dentures.  

PubMed

This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided. PMID:24746524

Fueki, Kenji; Ohkubo, Chikahiro; Yatabe, Masaru; Arakawa, Ichiro; Arita, Masahiro; Ino, Satoshi; Kanamori, Toshikazu; Kawai, Yasuhiko; Kawara, Misao; Komiyama, Osamu; Suzuki, Tetsuya; Nagata, Kazuhiro; Hosoki, Maki; Masumi, Shin-ichi; Yamauchi, Mutsuo; Aita, Hideki; Ono, Takahiro; Kondo, Hisatomo; Tamaki, Katsushi; Matsuka, Yoshizo; Tsukasaki, Hiroaki; Fujisawa, Masanori; Baba, Kazuyoshi; Koyano, Kiyoshi; Yatani, Hirofumi

2014-04-01

363

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

NASA Astrophysics Data System (ADS)

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.

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

364

Thermoplastic microfluidic devices and their applications in protein and DNA analysis  

PubMed Central

Microfluidics is a platform technology that has been used for genomics, proteomics, chemical synthesis, environment monitoring, cellular studies, and other applications. The fabrication materials of microfluidic devices have traditionally included silicon and glass, but plastics have gained increasing attention in the past few years. We focus this review on thermoplastic microfluidic devices and their applications in protein and DNA analysis. We outline the device design and fabrication methods, followed by discussion on the strategies of surface treatment. We then concentrate on several significant advancements in applying thermoplastic microfluidic devices to protein separation, immunoassays, and DNA analysis. Comparison among numerous efforts, as well as the discussion on the challenges and innovation associated with detection, is presented. PMID:21274478

Liu, Ke; Fan, Z. Hugh

2013-01-01

365

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

366

Thermoplastic matrix composites - LARC-TPI, polyimidesulfone and their blends  

NASA Technical Reports Server (NTRS)

Composites were fabricated from unidirectional unsized AS-4 carbon fiber and two baseline polyimides: benzophenone dianhydride-3,3'-diaminodiphenylsulfone (PISO2) and benzophenone dianhydride-3,3'-diaminobenzophenone (LARC-TPI). In addition, each polymer solution prior to prepregging was doped with various amounts of crystalline LARC-TPI powder to enhance melt flow during press molding. The 2:1, 1:1, and 1:2 ratios of crystalline to amorphous resin, respectively, were studied in the LARC-TPI system and the 1:2 ratio in the PISO2 system. Matrix characterization, prepreg fabrication/characterization and composite fabrication and physical/mechanical properties are described. The latter include three point short beam shear and flexure, dry and wet, as well as fracture toughness properties in selected compositions.

Johnston, Norman J.; St. Clair, Terry L.

1987-01-01

367

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.

2014-09-09

368

Polymers & People  

ERIC Educational Resources Information Center

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

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

2004-01-01

369

Polymer flooding  

Microsoft Academic Search

This book covers all aspects of polymer flooding, an enhanced oil recovery method using water soluble polymers to increase the viscosity of flood water, for the displacement of crude oil from porous reservoir rocks. Although this method is becoming increasingly important, there is very little literature available for the engineer wishing to embark on such a project. In the past,

Littmann

1988-01-01

370

Electroluminescent polymers  

Microsoft Academic Search

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

Leni Akcelrud

2003-01-01

371

Dynamics and thermodynamics of polymer glasses.  

PubMed

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

Cangialosi, D

2014-04-16

372

Improved sensitivity of dye-doped thermoplastic disks for holographic data storage  

Microsoft Academic Search

Holographic data storage materials based on dye-doped thermoplastics are currently under development. The materials are injection moldable into the standard disk format and have much lower shrinkage than photopolymer materials. Injection-molded disks with dyes from the class of o-nitrostilbenes presented acceptable capacities but a very low sensitivity. In this paper, theoretical analysis and experimental results on the sensitivity and sensitivity

Xiaolei Shi; Christoph Erben; Brian Lawrence; Eugene Boden; Kathryn L. Longley

2007-01-01

373

The structure and properties of weld lines in injection molded thermoplastics  

E-print Network

THE STRUCTURE AND PROPERTIES OF WELD LINES IN INJECTION MOLDED THEBMOPLAST1CS A Thesis by ALI IHSAN MANISALI Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OP... 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...

Manisali, Ali Ihsan

2012-06-07

374

Through-transmission ultrasonics for on-line sensing and control of thermoplastic fusion bonding processes  

Microsoft Academic Search

The focus of this work is to develop Through-Transmission Ultrasonics (TTU) as a process monitoring technique for non-intrusive, on-line control of thermoplastic fusion bonding. A model is developed to predict the TTU amplitude of a fusion bond by joining the theory of ultrasonic wave propagation through multilayered structures with a model for the evolution of intimate contact at the material

Kirk David Tackitt

1999-01-01

375

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

Microsoft Academic Search

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

Raji Sundararajan

2010-01-01

376

Thermoplastic corn starch\\/clay hybrids: Effect of clay type and content on physical properties  

Microsoft Academic Search

Thermoplastic corn starch (TPS) hybrids, plasticized with glycerol and reinforced with two types of clay (sodium montmorillonite and Cloisite® 30B), were prepared by melt-extrusion. Scanning electron microscopy was used to visualize extrudates morphology. The effects of clay content and of glycerol content on the physical properties of extrudates were evaluated. As determined by contact angle measurements and X-ray diffraction, the

N. F. Magalhães; C. T. Andrade

2009-01-01

377

N -(2-Hydroxyethyl)formamide as a new plasticizer for thermoplastic starch  

Microsoft Academic Search

N-(2-Hydroxyethyl)formamide (HF) was synthesized efficiently and used as a new plasticizer for corn starch to prepare thermoplastic\\u000a starch (TPS). The hydrogen bond interaction between HF and starch was proved by Fourier-transform infrared (FT-IR) spectroscopy.\\u000a Scanning electron microscope (SEM) revealed that starch granules were completely disrupted and a continuous phase was obtained.\\u000a The crystallinity of corn starch and HF-plasticized TPS (HTPS)

Hongguang Dai; Peter R. Chang; Fei Peng; Jiugao Yu; Xiaofei Ma

2009-01-01

378

Analysis of the whitening phenomenon of a thermoplastic elastomer article by UV weathering  

Microsoft Academic Search

A thermoplastic elastomer (TPE) article composed of polypropylene (PP) and ethylene-propylene-diene terpolymer (EPDM) was weathered by exposure to UV radiation of wavelength 340 nm for 80 days. The aged sample surface changed to grayish-white. The aged surfaces were analyzed using GC\\/MS, an image analyzer, SEM, EDX and ATR-FTIR to examine the cause of the whitening. Organic materials bloomed on the aged

Sung-Seen Choi; Hye-Seung Chung; Yong-Tae Joo; Byung-Kwon Min; Seong-Hoon Lee

2011-01-01

379

Thermal simulation of quartz tube infra-red heaters used in the processing of thermoplastic composites  

Microsoft Academic Search

The use of infra-red heaters in the processing of thermoplastic composites is increasing due to the potential for quick process cycle times. Accurate modelling of the heating characteristics will help processors predict heat-up times for their processes and avoid the disadvantages associated with infra-red heating. This paper deals with the modelling of quartz tube infra-red heaters, taking into account both

M. T. Brogan; P. F. Monaghan

1996-01-01

380

Surface modification of thermoplastic polyurethane in order to enhance reactivity and avoid cell adhesion  

Microsoft Academic Search

Recently, the definition of coating procedures which leads to strong cell repellent surfaces has been an extremely important\\u000a issue. In the present study, the cell repellency of thermoplastic polyurethane material (Elastollan®1180A50) surfaces was\\u000a achieved by chemical treatment. Samples of Elastollan®1180A50 processed by injection molding, were oxidized with hydrogen\\u000a peroxide (H2O2) and then impregnated with poly(ethylene glycol). The oxidation time was

Patricia Alves; Jean-Pierre Kaiser; Janne Haack; Natalie Salk; Arie Bruinink; Hermínio C. de Sousa; Maria Helena Gil

2009-01-01

381

Surface charge, electroosmotic flow and DNA extension in chemically modified thermoplastic nanoslits and nanochannels.  

PubMed

Thermoplastics have become attractive alternatives to glass/quartz for microfluidics, but the realization of thermoplastic nanofluidic devices has been slow in spite of the rather simple fabrication techniques that can be used to produce these devices. This slow transition has in part been attributed to insufficient understanding of surface charge effects on the transport properties of single molecules through thermoplastic nanochannels. We report the surface modification of thermoplastic nanochannels and an assessment of the associated surface charge density, zeta potential and electroosmotic flow (EOF). Mixed-scale fluidic networks were fabricated in poly(methylmethacrylate), PMMA. Oxygen plasma was used to generate surface-confined carboxylic acids with devices assembled using low temperature fusion bonding. Amination of the carboxylated surfaces using ethylenediamine (EDA) was accomplished via EDC coupling. XPS and ATR-FTIR revealed the presence of carboxyl and amine groups on the appropriately prepared surfaces. A modified conductance equation for nanochannels was developed to determine their surface conductance and was found to be in good agreement with our experimental results. The measured surface charge density and zeta potential of these devices were lower than glass nanofluidic devices and dependent on the surface modification adopted, as well as the size of the channel. This property, coupled to an apparent increase in fluid viscosity due to nanoconfinement, contributed to the suppression of the EOF in PMMA nanofluidic devices by an order of magnitude compared to the micro-scale devices. Carboxylated PMMA nanochannels were efficient for the transport and elongation of ?-DNA while these same DNA molecules were unable to translocate through aminated nanochannels. PMID:25369728

Uba, Franklin I; Pullagurla, Swathi R; Sirasunthorn, Nichanun; Wu, Jiahao; Park, Sunggook; Chantiwas, Rattikan; Cho, Yoon-Kyoung; Shin, Heungjoo; Soper, Steven A

2014-12-01

382

Development of ACP reinforced thermoplastic composites as an alternative to open mold processing  

NASA Astrophysics Data System (ADS)

Thermoplastic/foam/glass composite technology provides a method of producing large structural parts without styrene or volatile organic compounds (VOCs). High-quality parts can be molded at a low cost by combining vacuum forming technology with a low-pressure urethane reinforcement technique. This process eliminates atomization of paint or gelcoats, styrene emissions from FRP, and associated solvents and chemicals required in the normal processing of fiberglass. Secondary operations also can be streamlined by parts consolidation in the reinforcement process.

O'Neill, Michael A.

1992-01-01

383

Impact damage characterisation of thermoplastic matrix composites using transmission transient thermography  

Microsoft Academic Search

In this work, IR thermography is used as a non-destructive tool for impact damage characterisation on thermoplastic E-glass\\/polypropylene composites for automotive applications. The aim of this experimentation was to compare impact resistance and to characterise damage patterns of different laminates, in order to provide indications for their use in components. Two E-glass\\/polypropylene composites, commingled Twintex (with three different weave structures:

Carlo Santulli

2003-01-01

384

Fracture behaviors of PP\\/mPE thermoplastic vulcanizate via peroxide crosslinking  

Microsoft Academic Search

Peroxide cured PP\\/metallocene polyethylene (mPE) to form a novel thermoplastic vulcanizate has been prepared. Metallocene polyethylenes with two different levels of comonomer contents were chosen for the investigation. The mixing of mPE (40wt%) and PP (60wt%) containing various dosages of peroxide was performed to activate dynamic cure using an internal mixer. Thermal behaviors remain largely unchanged for PP, indicating the

S.-M. Lai; F.-C. Chiu; T.-Y. Chiu

2005-01-01

385

Electrospinning Thermoplastic Polyurethane-Contained Collagen Nanofibers for Tissue-Engineering Applications  

Microsoft Academic Search

Electrospinning is a new method used in tissue engineering. It can spin fibers in nanoscale by electrostatic force. A series of thermoplastic polyurethane (TPU)\\/collagen blend nanofibrous membranes was prepared with different weight ratios and concentrations via electrospinning. The two biopolymers used 1,1,1,3,3,3,-hexafluoro-2-propanol (HFP) as solvent. The electrospun TPU-contained collagen nanofibers were characterized using scanning electron microscopy (SEM), XPS spectroscopy, atomic

Rui Chen; Lijun Qiu; Qinfei Ke; Chuanglong He; Xiumei Mo

2009-01-01

386

Stress-strain behavior of the electrospun thermoplastic polyurethane elastomer fiber mats  

Microsoft Academic Search

Thermoplastic polyurethane elastomer (TPUe) fiber mats were successfully fabricated by electrospinning method. The TPUe fiber\\u000a mats were subjected to a series of cycling tensile tests to determine the mechanical behavior. The electrospun TPUe fiber\\u000a mats showed non-linear elastic and inelastic characteristics which may be due to slippage of crossed fiber (non-bonded or\\u000a physical bonded structure) and breakage of the electrospun

Keunhyung Lee; Bongseok Lee; Chihun Kim; Hakyong Kim; Kwanwoo Kim; Changwoon Nah

2005-01-01

387

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

Microsoft Academic Search

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

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

2002-01-01

388

Microstructure-based deep-drawing simulation of knitted fabric reinforced thermoplastics by homogenization theory  

Microsoft Academic Search

Process simulation of fiber reinforced composite materials is an important research theme for the development of low-cost and advanced functional composite materials. This paper aims at the simulation of deep-drawing process of knitted fiber reinforced thermoplastics and its verification. The feature of the simulation is that the large deformation of the knitted microstructures can be traced everywhere in the deep-drawn

N. Takano; Y. Ohnishi; M. Zako; K. Nishiyabu

2001-01-01

389

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

Microsoft Academic Search

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

Yusuke Suzuki; Masumi Yamada; Minoru Seki

2010-01-01

390

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

Microsoft Academic Search

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

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

2005-01-01

391

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

SciTech Connect

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.

Yoon, Kwangjoon.

1990-01-01

392

Current leakage prevention in resistance welding of carbon fibre reinforced thermoplastics  

Microsoft Academic Search

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

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

2008-01-01

393

Debinding mechanisms in thermoplastic processing of a Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-?)- stearic acid-polystyrene mixture.  

PubMed

In the present study, we address the interaction between a thermoplastic binder system and Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-?) (BSCF) during thermal treatment of the thermoplastic feedstock. BSCF powder was coated with different amounts of stearic acid (SA) acting as a surfactant. Oxygen release from the uncoated BSCF surface changes the decomposition of polystyrene (PS) in inert atmospheres from a pyrolytic to a thermoxidative mechanism, thereby decreasing the break-down temperature and the activation energy. In mixtures with coated BSCF powder, the decomposition products of SA carbonatize the BSCF surface, which inhibits oxygen release. Mass spectrometry of the breakdown products indicates that the decomposition of SA in the presence of BSCF also modifies the decomposition pathway of PS. The influence of BSCF on the polymer decomposition reaction in air is not as strong. Oxygen diffusion seems to be responsible for the differences to pure PS in reaction rates and the activation energies. PMID:23281298

Salehi, Mehdi; Clemens, Frank; Otal, Eugenio H; Ferri, Davide; Graule, Thomas; Grobéty, Bernard

2013-02-01

394

The use of the flexural modulus in the comparison of fiber orientation models for concentrated suspensions in short fiber-filled thermoplastics.  

E-print Network

??Advances in modeling spatially varying fiber orientation within an injection molded thermoplastic composite part have led to better structural designs and manufacturing efficiencies by optimizing… (more)

Lewis, Benjamin W.

2013-01-01

395

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

PubMed

Reinforcement of a novel poly(phenylene ether) (PPE) based thermoplastic elastomer (TPE), i.e., styrene-ethylene-butylene-styrene (SEBS)/ethylene vinyl acetate (EVA) and PPE-polystyrene (PS), was studied to develop a reinforced thermoplastic elastomer or thermoplastic vulcanizate (TPV). An effort was made to reinforce selectively the elastomeric dispersed phase of EVA by silica nanoparticles and silica sol-gel precursors, like alkoxy orthosilanes, using twin-screw extrusion and injection molding processes. Improvement of tensile strength and percent elongation at break was observed both with silica nanoparticles and tetraethoxy orthosilane (TEOS). Addition of TEOS transformed the dispersed EVA lamellar morphology into semispherical domains as a consequence of possible crosslinking. Soxhlet extraction was done on the silica and TEOS reinforced materials. The insoluble residues collected from both the silica and TEOS reinforced samples were analyzed in detail using both morphological and spectroscopic studies. This extensive study also provided an in-depth conceptual understanding of the PPE based TPE behavior upon reinforcement with silica nanoparticles and silica sol-gel precursors and the effect of reinforcement on recycling behavior. PMID:18572622

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

2008-04-01

396

Auto-synchronized laser scanning range sensor for thermoplastic pavement marking material thickness measurement  

NASA Astrophysics Data System (ADS)

Pavement marking materials provide delineation on highways around the world. The condition of the marking materials is very important for the driver's safety as well as the comfort and the driving expenses. Currently thermoplastic pavement marking materials (TPMM) are widely used in states. Measuring the thickness of TPMM on pavement is an essential index to monitor the contractors, calculate durability of marking materials, and provide better information for the pavement marking evaluation. In recent years to measure the thickness of TPMM, a procedure involving pre-embedded plates sprayed with the marking materials has been widely accepted. This method is labor intensive, and cannot obtain a continuous-thickness profile. Therefore there are demands to develop a high-speed automatic measuring system for determining the thickness and uniformity of marking materials. In this paper, a laser range sensor based on auto-synchronized laser scanning is proposed for the thermoplastic pavement marking material thickness measurement. Compare to classical triangulation method, this approach doesn't scarify the system resolution for large field of view and it is more suitable for highway speed measurement. To achieve high speed measurement, PSD (Position Sensitive Detector) is used in the prototype system instead of CCD (Charge Couple Device) in traditional auto-synchronized system. The standoff distance and transverse scan range of the prototype system both are 1 foot. The lab test results show that the prototype system can measure the thermoplastic type thickness with error in 5mil at laser scanning rate up to 50Hz.

Sun, Wei; Chen, Xuemin; Chen, Yuanhang; Ekbote, Aditya; Liu, Richard Ce

2006-03-01

397

High-speed laser cutting of superposed thermoplastic films: thermal modeling and process characterization  

NASA Astrophysics Data System (ADS)

Common thermoplastic films used in the packaging industry have a thickness lower than 100 ?m, and present low absorption to CO 2 laser radiation. This characteristic renders the use of cutting parameters, predicted by models developed for thicker thermoplastics inappropriate. In addition, the usual procedures involve the use of an assisting gas, responsible for removing the melted material, which, when processing thin films, induces changes in position in the material. A new theoretical model describing the temperature distribution on thin thermoplastic material during laser cutting was later developed. The heat conduction was solved analytically by the Green function method and heating and cooling thermal stress evolution was taken into consideration. The laser beam diameter over the samples provides the possibility of obtaining two cut operations: a simple cut, on beam focus, and a cut with welding, defocusing the beam. Engineering parameters predicted by the model were applied to cutting superposed high- and low-density polyethylene and polypropylene samples, transparent and white, with thicknesses between 10 and 100 ?m, and experimentally validated. Proper modeling and the introduction of a reflective substrate under the samples allowed the improvement of process efficiency and the achievement of cutting operations up to 20 m s -1, and cut with welding up to 14 m s -1; an order of magnitude of improvement on industrial speeds previously attained for this operation.

Coelho, João M. P.; Abreu, Manuel A.; Carvalho Rodrigues, F.

2004-07-01

398

A micrographic study of bending failure in five thermoplastic/carbon fiber composite laminates  

NASA Technical Reports Server (NTRS)

The local deformation and failure sequences of five thermoplastic matrix composites were microscopically observed while bending the samples in a small fixture attached to a microscope stage. The themoplastics are polycarbonate, polysulfone, polyphenylsulfide, polyethersulfone, and polyetheretherketone. Comparison was made to an epoxy matrix composite, 5208/T-300. Laminates tested are (0/90) sub 2S, with outer ply fibers parallel to the beam axis. Four point bending was used at a typical span-to-thickness ratio of 39:1. It was found that all of the thermoplastic composites failed by abrupt longitudinal compression buckling of the outer ply. Very little precursory damage was observed. Micrographs reveal typical fiber kinking associated with longitudinal compression failure. Curved fracture surfaces on the fibers suggest they failed in bending rather than direct compression. Delamination was suppressed in the thermoplastic composites, and the delamination that did occur was found to be the result of compression buckling, rather than visa-versa. Microbuckling also caused other subsequent damage such as ply splitting, transverse ply shear failure, fiber tensile failure, and transverse ply cracking.

Yurgartis, S. W.; Sternstein, S. S.

1987-01-01

399

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

SciTech Connect

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.

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

1998-12-31

400

Polymer powder prepregging: Scoping study  

NASA Technical Reports Server (NTRS)

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

Throne, James L.

1988-01-01

401

Tough, processable semi-interpenetrating polymer networks from monomer reactants  

NASA Technical Reports Server (NTRS)

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

Pater, Ruth H. (inventor)

1994-01-01

402

Smart polymers for implantable electronics  

NASA Astrophysics Data System (ADS)

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.

Ware, Taylor H.

403

Toughening mechanisms in interfacially modified HDPE/thermoplastic starch blends.  

PubMed

The mechanical behavior of polymer blends containing 80wt% of HDPE and 20wt% 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

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

2014-12-19

404

Characterization of PEEK and short-fiber PEEK thermoplastic composites  

SciTech Connect

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.

Motz, H.

1987-01-01

405

Processing of continuous fiber composites using thermoplastic polyimide matrix resins  

SciTech Connect

Composites have been produced which contain a solvent resistant polyimide matrix with favorable physical properties. The polyimide matrix resin has been designated as P12. The prepegs used to produce the composite contain a low molecular weight resin which is the polyamic acid precursor to P12. Polymerization and imidization of the precursor resin occurs in-situ during processing. Similar commercial systems are often processed in an autoclave and pressure is used at high temperatures to obtain consolidation between prepreg laminates. Pressure is generally applied after polymerization and imidization are complete and at temperatures above the melting point of the polymer. In this research a significant decrease in composite void content was obtained by applying pressure earlier in the cure. Obtaining composites with low void content with these types of systems can be difficult. This is due in part to the generation of low molecular weight reaction by products, water and methanol. High void content results in a decrease in the physical properties of the composite structure. This is especially true for fracture properties. An empirical equation was used to describe the rate of resin removal from the composite to the bleeder cloth during processing. This equation is based on Springer-Loos resin flow model. The conditions in which this model does not apply were also determined. Determining resin removal rates is helpful in producing composites with consistent fiber/resin ratios. In addition, conditions which favor void growth can be prevented.

Kranjc, M.D.

1993-01-01

406

e-Polymers 2009, no. 109 http://www.e-polymers.org  

E-print Network

transitions: aging and gamma sterilization of vulcanized thermoplastic elastomers Witold Brostow,a * Sameer: 19 September, 2009) Abstract: We have studied nine thermoplastic vulcanizate elastomers (TPVs devices [1-3]. In particular, thermoplastic vulcanizate elastomers (TPVs) have found use in medical

North Texas, University of

407

Branched Polymers  

E-print Network

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

Richard Kenyon; Peter Winkler

2007-09-14

408

Polymer Synthesis  

NSDL National Science Digital Library

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

Teegarden, David

2004-01-01

409

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

NASA Astrophysics Data System (ADS)

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

Nair, Abilash R.

410

Experimental study on melting and flowing behavior of thermoplastics combustion based on a new setup with a T-shape trough  

Microsoft Academic Search

The objective of this work is to quantitatively study the burning characteristics of thermoplastics. A new experimental setup with a T-shape trough is designed. Based on this setup, the loop mechanism between the wall fire and pool fires induced by the melting and dripping of thermoplastic can be well simulated and studied. Additionally, the flowing characteristics of pool fires can

Qiyuan Xie; Heping Zhang; Ruibo Ye

2009-01-01

411

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)

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.

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

1998-01-01

412

Understanding corrosion protection and failure through model polymers in thin films  

NASA Astrophysics Data System (ADS)

When developing a model polymeric system to facilitate in the detection of molecular and microscopic events that preface macroscopic corrosive failure; a better understanding of how polymers can indicate corrosion was accomplished. Initially, the thought that molecular chain scission as a necessity for corrosion to occur had to be tested. Through the utilization of high molecular weight thermoplastic (HMWTP) model polymers, it was found that corrosion protection did not correlate to the quantity of weak bonds within an epoxy-amine polymer matrix. Therefore more sensitive methods of detecting corrosion had to be developed since changes within the polymer matrix did not provide thorough data for pre-failure events. Incorporating small molecules that indicate corrosion events into organic polymer coatings, however, did provide sufficient data into when steel substrates were about to fail. It was determined that these molecules, whether colorimetric or fluorescent, were able to capture events at the metal-polymer interface that would directly lead to rust formation. To further the understanding of predicting corrosion, fluorescent molecules were attached to polymer covalently and were able to quantify corrosion events at the highest confidence that no small molecules were moving and providing false results. The development of this corrosion characterization technique should provide plentiful insight into how polymers and metals fail in a real-time nondestructive manner that is realistic to real-world testing protocols.

Hanna, Joshua Smith

413

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

414

Loading rate effect on interlaminar fracture toughness of a thermoplastic composite  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

415

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

416

Optimized replication of interferometrically generated deep diffractive structures by embossing into thermoplastics  

NASA Astrophysics Data System (ADS)

New optical elements can be realized interferometrically by generating holographic diffractive structures. For lasers in the infrared spectral region the rulings of these structures need to be 2 to 5 times deeper than in common uses. By structuring photoresists holographically, varying different parameters, ruling depths of 24 microns and depth to grating constants of 1.5 could be performed. These structures had been applied as masks to reactive ion etching in glass and copper. For economic embossing replication techniques nickel stampers had been manufactured by electroforming the diffractive photoresist structures. Optimization of the embossing parameters has been carried out successfully regarding different thermoplastic materials and the achievable diffraction efficiency.

Lensch, Guenter; Lippert, Peter; Kreitlow, Horst; Budzinski, Christel

1993-04-01

417

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

NASA Astrophysics Data System (ADS)

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.

Detyothin, Sukeewan

418

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

SciTech Connect

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.

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

419

Glue Polymer  

NSDL National Science Digital Library

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.

Mid-continent Research for Education and Learning (McREL); Jacobs, Steve

2004-01-01

420

Ferroelectric polymers  

Microsoft Academic Search

In the early 1970s it became clear that the polymer polyvinylidene fluoride is ferroelectric. There have been extensive studies of its properties and of the properties of copolymers of vinylidene fluoride with tri- or tetra-fluoroethylene. This work has led to a fairly complete understanding of the ferroelectric and related properties of these materials. The emphasis in this review is on

R. G. Kepler; R. A. Anderson

1992-01-01

421

Polymer solutions  

DOEpatents

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.

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

2011-07-26

422

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

PubMed

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

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

2013-04-01

423

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

PubMed

The ability of the rapid-capacitive discharge approach to access optimal viscosity ranges in metallic glasses for thermoplastic processing is explored. Using high-speed thermal imaging, the heating uniformity and stability against crystallization of Zr35Ti30Cu7.5Be27.5 metallic glass heated deeply into the supercooled region is investigated. The method enables homogeneous volumetric heating of bulk samples throughout the entire supercooled liquid region at high rates (~10(5)?K/s) sufficient to bypass crystallization throughout. The crystallization onsets at temperatures in the vicinity of the "crystallization nose" were identified and a Time-Temperature-Transformation diagram is constructed, revealing a "critical heating rate" for the metallic glass of ~1000?K/s. Thermoplastic process windows in the optimal viscosity range of 10(0)-10(4)?Pa·s are identified, being confined between the glass relaxation and the eutectic crystallization transition. Within this process window, near-net forging of a fine precision metallic glass part is demonstrated. PMID:25269892

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

2014-01-01

424

Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge  

PubMed Central

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

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

2014-01-01

425

Quick, stable, safe and economical preheating of glass mat reinforced thermoplastics in a contact heating oven  

SciTech Connect

Glass mat reinforced thermoplastics (GMT) which belong to the group of sheet thermoplastic composites (STC) are processed in compression moulding for structural parts. Before moulding the material, it has to be preheated currently by IR-radiation or by air convection. Using a contact heating oven, preheating can be speeded up combined with a significant higher energetic efficiency. But up to now, operation using the contact heating method failed due to the tackiness of the matrix material in solid state. IKV has recently created a solution for the problem of tackiness by transporting the glass mat reinforced material between two belts coated with PTFE through a contact oven. This preheating line includes a shock-cooler to quickly cool down a thin layer of the GMT`s surface. By this, separating the GMT from the PTFE without leaving particles on the belt is possible. The contact heating method not only includes the advantage of a significant higher energetic efficiency, but also benefits in processing. The risk of matrix degradation is distinctly reduced in comparison to other preheating methods, since the material does not expand in thickness for more than 200% and therefore air cannot come intensively into contact with the material. Consequently, the contact preheating is well qualified for matrix materials susceptible for oxidation. In this paper the physical coherence, the adhesion and the cohesion of GMT, are, described. Furthermore experimental results with a contact preheating line are presented.

Michaeli, W.; Starke, J. [Institut fuer Kunststoffverarbeitung, Aachen (Germany)

1993-12-31

426

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

SciTech Connect

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.

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

2008-05-15

427

Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

428

Bio-thermoplastics from grafted chicken feathers for potential biomedical applications.  

PubMed

This research demonstrated the feasibility of using bio-thermoplastics developed from chicken feathers grafted with acrylates and methacrylates as scaffolds for tissue engineering. Keratin, the major protein in feathers, is a highly crosslinked biopolymer that has been reported to be biocompatible. However, it is difficult to break the disulfide bonds and make keratin soluble to develop materials for tissue engineering and other medical applications. Previously, keratin extracted from feathers using alkaline hydrolysis has been made into scaffolds but with poor water stability and mechanical properties. In this study, thermoplastic films were compression molded from chicken feathers grafted with 6 different acrylate monomers. The influence of the concentration and structures of grafted monomers on grafting parameters and the tensile strength, water stability and cytocompatibility of grafted feathers compression molded into films were investigated. It was found that the grafted feather films were water stable and had good strength and better supported cell growth than poly(lactic acid) films. Grafted feathers demonstrated the potential to be used for fabrication of biomaterials for various biomedical applications. PMID:23707850

Reddy, Narendra; Jiang, Qiuran; Jin, Enqi; Shi, Zhen; Hou, Xiuliang; Yang, Yiqi

2013-10-01

429

Rapid Processing of Net-Shape Thermoplastic Planar-Random Composite Preforms  

NASA Astrophysics Data System (ADS)

A novel thermoplastic composite preforming and moulding process is investigated to target cost issues in textile composite processing associated with trim waste, and the limited mechanical properties of current bulk flow-moulding composites. The thermoplastic programmable powdered preforming process (TP-P4) uses commingled glass and polypropylene yarns, which are cut to length before air assisted deposition onto a vacuum screen, enabling local preform areal weight tailoring. The as-placed fibres are heat-set for improved handling before an optional preconsolidation stage. The preforms are then preheated and press formed to obtain the final part. The process stages are examined to optimize part quality and throughput versus processing parameters. A viable processing route is proposed with typical cycle times below 40 s (for a plate 0.5 × 0.5 m2, weighing 2 kg), enabling high production capacity from one line. The mechanical performance is shown to surpass that of 40 wt.% GMT and has properties equivalent to those of 40 wt.% GMTex at both 20°C and 80°C.

Jespersen, S. T.; Baudry, F.; Schmäh, D.; Wakeman, M. D.; Michaud, V.; Blanchard, P.; Norris, R. E.; Månson, J.-A. E.

2009-02-01

430

Method and apparatus for producing composites of materials exhibiting thermoplastic properties  

DOEpatents

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.

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

1992-01-01

431

Fabrication of thermoplastic ductile films of chitin butyrate/poly(?-caprolactone) blends and their cytocompatibility.  

PubMed

We fabricate thermoplastic films of chitin burtyrate (ChB)/poly(?-caprolactone) (PCL) blends with different degree of miscibility (miscible (M), partially miscible (PM), and immiscible (IM)), and examined the feasibility as a cell scaffold system through evaluating mechanical properties and cytocompatibility. We found a remediation of the brittleness and an increase in ductility of ChB by blending PCL for the M and PM blends. The blend films were subjected to alkaline hydrolysis (2-M NaOH/37°C/48h) with expectation of the improvement of the surface hydrophilicity and cell accessibility. ATR-FTIR spectroscopy of the alkaline-treated PM and IM films revealed that PCL component and ester side-chains of acyl chitin were selectively removed from the surface domain. L929 fibroblast cells well adhered and proliferated on these films. Therefore, the materials possess a great potential for the utilization as a thermoplastic cell scaffold in tissue engineering by adequate selection of the degree of miscibility and post treatment. PMID:25263898

Hashiwaki, Hiroki; Teramoto, Yoshikuni; Nishio, Yoshiyuki

2014-12-19

432

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

433

A comparative investigation of thermal and tribological properties of thermoplastic and thermosetting polyimides with similar structural formulae  

Microsoft Academic Search

PMR (polymerization of monomer reactants) type polyimide was synthesized and the homogeneous matrix resin solution (30–40% solid) was used to prepare film blocks for tribological tests. Compared with a thermoplastic polyimide with similar molecular formula and similar behavior of weight loss under heating, the high Tg and char yield of the PMR polyimide can be attributed to the self-reaction of

Hong Liu; Xianqiang Pei; Qihua Wang

2011-01-01

434

Beam flatness perturbation effects of a perforated thermoplastic immobilization device on 6 and 12 MeV electron beams  

Microsoft Academic Search

Purpose: Perforated thermoplastic masks are widely used in radiotherapy of head and neck malignancies. They provide for patient immobilization and increase setup reproducibility. Some oncology treatment centers cut mask portals (windows) for the beam to pass through; for those centers that do not, the mask affects beam fluence. The extent to which beam flatness is altered by such a mask

Revlon O. Williams; Peter A. S. Johnstone; Patrick J. Papin

1996-01-01

435

Randomized trial on two types of thermoplastic masks for patient immobilization during radiation therapy for head-and-neck cancer  

Microsoft Academic Search

PurposeRadiation therapy for head-and-neck cancer requires a reliable immobilization for an accurate and consistent treatment setup. This prospective, randomized study was done to compare two types of Posicast thermoplastic face masks, in terms of reproducibility, patient comfort, tolerability, and skin damage.

Lena Sharp; Freddi Lewin; Hemming Johansson; David Payne; Ansi Gerhardsson; Lars Erik Rutqvist

2005-01-01

436

Studies on the Rheology and the Mechanical Properties of Thermoplastic Elastomer from Latex Product Waste and High Density Polyethylene  

Microsoft Academic Search

Latex waste products contain rubber hydrocarbon of very high quality, which is only lightly cross linked. Selected wastes such as thread waste and glove waste were modified into processable materials by a novel economic process and thermoplastic elastomers were prepared by blending these modified waste materials with high density polyethylene in various proportions. The mechanical properties as well as the

S. Rajalekshmi; Rani Joseph

2002-01-01

437

Process-property studies of weld line strength and thin structure flow in high performance injection molded thermoplastics  

Microsoft Academic Search

The effects of operator controllable injection molding process parameters on weld line strength and thin structure flow of neat and short fiber reinforced injection molded polyetherimide and PEEK thermoplastics have been investigated using statistical experimental methods. Buckingham's Theorem was used to create empirical models which are consistent with the physics governing injection molding, relating processing to properties. In addition, a

J. S. Griffing; J. C. Seferis; J. M. Kenny; L. Nicolais

1991-01-01

438

Advanced Polymer  

NASA Technical Reports Server (NTRS)

In the mid-1980's, Langley developed a polyimide sulfone, combining desirable properties of two classes of polymers. Composites and other products made from polyimide sulfone can be used with solvents and corrosive fluids, are light weight, low cost and can be easily fabricated for a wide range of industrial uses. High Technology Systems, Inc. obtained a license for the polymer and was awarded a Small Business Innovation Research (SBIR) contract for development in a powder form. Although its principal use is as a matrix resin for composites, the material can also be used as a high temperature structural adhesive for aircraft structures and as a coating for protection from heat and radiation for electronic components.

1992-01-01

439

Periodic Polymers  

NASA Astrophysics Data System (ADS)

Periodic polymers can be made by self assembly, directed self assembly and by photolithography. Such materials provide a versatile platform for 1, 2 and 3D periodic nano-micro scale composites with either dielectric or impedance contrast or both, and these can serve for example, as photonic and or phononic crystals for electromagnetic and elastic waves as well as mechanical frames/trusses. Compared to electromagnetic waves, elastic waves are both less complex (longitudinal modes in fluids) and more complex (longitudinal, transverse in-plane and transverse out-of-plane modes in solids). Engineering of the dispersion relation between wave frequency w and wave vector, k enables the opening of band gaps in the density of modes and detailed shaping of w(k). Band gaps can be opened by Bragg scattering, anti-crossing of bands and discrete shape resonances. Current interest is in our group focuses using design - modeling, fabrication and measurement of polymer-based periodic materials for applications as tunable optics and control of phonon flow. Several examples will be described including the design of structures for multispectral band gaps for elastic waves to alter the phonon density of states, the creation of block polymer and bicontinuous metal-carbon nanoframes for structures that are robust against ballistic projectiles and quasi-crystalline solid/fluid structures that can steer shock waves.

Thomas, Edwin

2013-03-01

440

Electrically Conductive Metal Polymer Nanocomposites for Electronics Applications  

NASA Astrophysics Data System (ADS)

An electrically conductive nanocomposite composed of thermoplastic elastomer and nanosized silver particles was developed. Nanosized silver particles were produced by the liquid flame spraying method. Nanocomposites were produced employing a batch mixing process in the melt state. The percolation curve and the minimum resistivity as a function of silver content were defined. A plasticized styrene block-copolymer was used as the matrix polymer. The results showed that the agglomeration of the silver particles has a major influence on the percolation threshold and the resistivity of the compound. With slightly agglomerated silver particles a percolation threshold with a silver content of 13 16 vol.% was achieved. The corresponding resistivity was 2.0 × 10-1 ? cm. With heavily agglomerated particles the resistivity is high (2.9 × 103 ? cm), even with a silver content of 20 vol.%. With a low primary silver particle size (under 100 nm), the resistivity of the compound was high (5.6 × 105 ? cm).

Karttunen, Mikko; Ruuskanen, Pekka; Pitkänen, Ville; Albers, Willem M.

2008-07-01

441

Thermal sonic analysis of polymer matrices and composites  

SciTech Connect

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.

Woo, E.M.; Seferis, J.C.

1987-03-01

442

New photoactive polymers: Azobenzene elastomers  

NASA Astrophysics Data System (ADS)

Azobenzene-containing elastomers have been synthesized for the first time. By free radical polymerization of methacrylate or acrylate-based monomers bearing an azobenzene moiety in solution with dissolved styrene-butadiene-styrene (SBS) triblock copolymer, azobenzene side-chain liquid crystalline polymer (SCLCP) was grafted on the rubbery polybutadiene (PB) central block of SBS. Similar to SBS, the resultant azobenzene SCLCP-grafted SBS was a thermoplastic elastomer, for which polystyrene (PS) cylindrical microdomains behave as physical cross-links. Three different azobenzene SCLCCs, differing in chain backbone or terminal group on the azobenzene moiety, were used to prepare azobenzene elastomers. Their thin films obtained from solution casting were transparent and could be repeatedly stretched at room temperature. Polarized UV-vis and infrared spectroscopy were used to investigate the coupling effects from film deformation and photoisomerization of azobenzene chromophore in the elastomer. Stretching the film effectively induces a long-range orientation of azobenzene mesogenic groups (in the trans form) along the strain direction due to the liquid crystalline nature of the azobenzene polymer. When the stretched film is exposed to polarized or unpolarized UV light (360 nm), the orientation of trans-azobenzene is erased as a result of the trans-to-cis photoisomerization that corresponds to a photochemical liquid crystal-to-isotropic phase transition. On polarized or unpolarized visible irradiation (440 nm), the cis-to-trans back-isomerization recovers the orientation of trams-azobenzene mesogens. This coupled mechanical and optical effect allows a reversible optical switching between orientation-on and orientation-off states to be realized on stretched films. The study shows that the azobenzene SCLCP grafted on SBS is important since its glass and mesophase transition temperatures determine greatly the degree of stretching induced orientation while its cis isomer concentration at the photostationary state affects the erasure of orientation on UV light irradiation. Moreover, experiments found no evidence of reorientation of azobenzene mesogens in stretched films under linearly polarized UV irradiation, but during the orientation recovery with linearly polarized visible light, a contribution from photoinduced orientation of azobenzene becomes significant.

Bai, Shuying

2003-07-01

443

Polymer Coats Leads on Implantable Medical Device  

NASA Technical Reports Server (NTRS)

Langley Research Center s Soluble Imide (LaRC-SI) was discovered by accident. While researching resins and adhesives for advanced composites for high-speed aircraft, Robert Bryant, a Langley engineer, noticed that one of the polymers he was working with did not behave as predicted. After putting the compound through a two-stage controlled chemical reaction, expecting it to precipitate as a powder after the second stage, he was surprised to see that the compound remained soluble. This novel characteristic ended up making this polymer a very significant finding, eventually leading Bryant and his team to win several NASA technology awards, and an "R&D 100" award. The unique feature of this compound is the way that it lends itself to easy processing. Most polyimides (members of a group of remarkably strong and incredibly heat- and chemical-resistant polymers) require complex curing cycles before they are usable. LaRC-SI remains soluble in its final form, so no further chemical processing is required to produce final materials, like thin films and varnishes. Since producing LaRC-SI does not require complex manufacturing techniques, it has been processed into useful forms for a variety of applications, including mechanical parts, magnetic components, ceramics, adhesives, composites, flexible circuits, multilayer printed circuits, and coatings on fiber optics, wires, and metals. Bryant s team was, at the time, heavily involved with the aircraft polymer project and could not afford to further develop the polymer resin. Believing it was worth further exploration, though, he developed a plan for funding development and submitted it to Langley s chief scientist, who endorsed the experimentation. Bryant then left the high-speed civil transport project to develop LaRC-SI. The result is an extremely tough, lightweight thermoplastic that is not only solvent-resistant, but also has the ability to withstand temperature ranges from cryogenic levels to above 200 C. The thermoplastic s unique characteristics lend it to many commercial applications; uses that Bryant believed would ultimately benefit industry and the Nation. "LaRC-SI," he explains, "is a product created in a government laboratory, funded with money from the tax-paying public. What we discovered helps further the economic competitiveness of the United States, and it was our goal to initiate the technology transfer process to ensure that our work benefited the widest range of people." Several NASA centers, including Langley, have explored methods for using LaRC-SI in a number of applications from radiation shielding and as an adhesive to uses involving replacement of conventional rigid circuit boards. In the commercial realm, LaRC-SI can now be found in several commercial products, including the thin-layer composite unimorph ferroelectric driver and sensor (THUNDER) piezoelectric actuator, another "R&D 100" award winner (Spinoff 2005).

2008-01-01

444

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

PubMed Central

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

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

2013-01-01

445

Thermal Behaviour of Nanocomposites based on Glycerol Plasticized Thermoplastic Starch and Cellulose Nanocrystallites  

NASA Astrophysics Data System (ADS)

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.

Kaushik, Anupama; Kaur, Ramanpreet

2011-12-01

446

Manufacturing and Process-based Property Analysis of Textile-Reinforced Thermoplastic Spacer Composites  

NASA Astrophysics Data System (ADS)

Novel woven spacer fabrics based on hybrid yarns are suitable for an efficient fabrication of three-dimensional composite structures in high volume production. In this paper, an innovative manufacturing process with short cycle times and high automatisation is introduced for textile-reinforced thermoplastic spacer structures suited for bending load cases. The different process steps hybrid yarn fabrication, weaving technology for three-dimensional textile preforms and consolidation with unique kinematics and hot pressing technology are described in detail. The bending properties of the manufactured spacer structures are evaluated by means of experiments as well as finite element simulations. Numerical parametric studies are performed in order to validate the influence of manufacturing tolerances on the bending stiffness of the spacer structures.

Hufenbach, Werner; Adam, Frank; Füßel, René; Krahl, Michael; Weck, Daniel

2012-12-01

447

Consequences of polylactide stereochemistry on the properties of polylactide-polymenthide-polylactide thermoplastic elastomers.  

PubMed

A series of polylactide-polymenthide-polylactide triblock copolymers containing either amorphous poly(D,L-lactide) or semicrystalline, enantiopure poly(L-lactide) or poly(D-lactide) end segments were synthesized. Small-angle X-ray scattering and differential scanning calorimetry data were consistent with microphase separation of these materials. The Young's moduli and ultimate tensile strengths of the semicrystalline triblock copolymers were 2- and 3-fold greater, respectively, than their amorphous analogs. Symmetric (50:50) and asymmetric (95:5) blends of the triblock copolymers containing two different enantomeric forms of the polylactide segments formed stereocomplex crystallites, as revealed by wide-angle X-ray scattering and differential scanning calorimetry. Compared to the enantiopure analogs, these blends exhibited similar ultimate elongations and tensile strengths, but significantly increased Young's moduli. Collectively, these results demonstrate that the properties of these new biorenewable thermoplastic elastomers can be systematically modulated by changing the stereochemistry of the polylactide end blocks. PMID:19775147

Wanamaker, Carolyn L; Bluemle, Michael J; Pitet, Louis M; O'Leary, Leslie E; Tolman, William B; Hillmyer, Marc A

2009-10-12

448

Development of an impact- and solvent-resistant thermoplastic composite matrix, phase 3  

NASA Technical Reports Server (NTRS)

The polyimide from BTDA 1,6-hexanediamine and m-phenylenediamine was selected from a prior study for the present study. Methods to prepare prepreg which would provide low void composites at low molding pressures from the thermoplastic polyimide were studied. Cresol solutions of the polyimide were applied to a balanced weave carbon fabric and the cresol removed prior to composite molding. Low void composites were prepared from smoothed prepregs at high pressures (34.5 MPa) and temperatures as low as 260 C. Lower molding pressures lead to higher void composites. Need for a lower melt viscosity in the neat resin is suggested as a requirement to achieve low void composites at low pressures. Some mechanical properties are included.

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

1985-01-01

449

Study of structurally efficient graphite-thermoplastic trapezoidal-corrugation sandwich and semisandwich panels  

NASA Astrophysics Data System (ADS)

The structural efficiency of compression-loaded trapezoidal-corrugation sandwich and semisandwich composite panels is studied to determine their weight savings potential. Sandwich panels with two identical face sheets and a trapezoidal corrugated core between them, and semisandwich panels with a corrugation attached to a single skin are considered. An optimization code is used to find the minimum weight designs for critical compressive load levels ranging from 3000 to 24,000 lb/in. Graphite-thermoplastic panels based on the optimal minimum weight designs were fabricated and tested. A finite-element analysis of several test specimens was also conducted. The results of the optimization study, the finite element analysis, and the experiments are presented.

Jegley, Dawn C.

1994-03-01

450

A constitutive law for thermo-plastic behaviour of rocks: an analogy with clays  

NASA Astrophysics Data System (ADS)

Thermo-mechanical behaviour of rocks shows phenomenological similarities to that of clays. A visible decrease of strength and an increase in ductility at elevated temperatures are observed in drained conditions. In undrained conditions the strength decrease is even more dramatic and the ductile behaviour may turn into the brittle one, if a sufficient amount of water is present in the pores at the start of the process, or it is being released during heating by the decomposition of hydrous minerals. Applying a thermo-plasticity theory, major macroscopical characteristics of behaviour may be modelled. According to this theory, the elastic domain is postulated as temperature dependent, shrinking with temperature; heating may result in expansive or compactive volumetric irreversible strain depending on the confining stress. This theory is applied to the modelling of heat effects on local changes of permeability around a cylindrical nuclear waste container disposed off in deep clays, and in the numerical simulation of a mechanism initiating deep earthquakes.

Hueckel, T.; Peano, A.; Pellegrini, R.

1994-09-01

451

Thermoplastic fusion bonding using a pressure-assisted boiling point control system.  

PubMed

A novel thermoplastic fusion bonding method using a pressure-assisted boiling point (PABP) control system was developed to apply precise temperatures and pressures during bonding. Hot embossed polymethyl methacrylate (PMMA) components containing microchannels were sealed using the PABP system. Very low aspect ratio structures (AR = 1/100, 10 ?m in depth and 1000 ?m in width) were successfully sealed without collapse or deformation. The integrity and strength of the bonds on the sealed PMMA devices were evaluated using leakage and rupture tests; no leaks were detected and failure during the rupture tests occurred at pressures greater than 496 kPa. The PABP system was used to seal 3D shaped flexible PMMA devices successfully. PMID:22728966

Park, Taehyun; Song, In-Hyouk; Park, Daniel S; You, Byoung Hee; Murphy, Michael C

2012-08-21

452

Thermo-mechanical behaviors of thermoplastic starch derived from sugar palm tree (Arenga pinnata).  

PubMed

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

Sahari, J; Sapuan, S M; Zainudin, E S; Maleque, M A

2013-02-15

453

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

454

From Process Modeling to Elastic Property Prediction for Long-Fiber Injection-Molded Thermoplastics  

SciTech Connect

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

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

455

Bonding and nondestructive evaluation of graphite/PEEK composite and titanium adherends with thermoplastic adhesives  

NASA Technical Reports Server (NTRS)

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.

Hodges, W. T.; Tyeryar, J. R.; Berry, M.

1985-01-01

456

Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation  

NASA Astrophysics Data System (ADS)

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.

Giraud, Isabelle; Franceschi-Messant, Sophie; Perez, Emile; Lacabanne, Colette; Dantras, Eric

2013-02-01

457

Mechanical properties of long carbon fiber reinforced thermoplastic (LFT) at elevated temperature  

NASA Astrophysics Data System (ADS)

Long fiber reinforced thermoplastics (LFT) possess high specific modulus and strength, superior damage tolerance and fracture toughness and have found increasing use in transportation, military, and aerospace applications. However, one of the impediments to utilizing these materials is the lack of performance data in harsh conditions, especially at elevated temperature. In order to quantify the effect of temperature on the mechanical properties of carbon fiber reinforced thermoplastic composites, carbon fiber PAA composite plates containing 20% and 30% carbon fiber were produced using extrusion/compression molding process and tested at three representative temperatures, room temperature (RT 26°C), middle temperature (MID 60°C) and glass transition temperature (Tg 80°C). A heating chamber was designed and fabricated for the testing at elevated temperature. As temperature increases, flexural modulus, flexural strength, tensile modulus and tensile strength decrease. The highest reduction observed in stiffness (modulus) values of 30% CF/PAA at Tg in the 00 orientation is 75%. The reduction values were larger for the transverse (perpendicular to flow direction) samples than the longitudinal (flow direction) samples. The property reduction in 30% CF/PAA is larger than 20% CF/PAA. Furthermore, an innovative method was developed to calculate the fiber content in carbon fiber reinforced composites by burning off the neat resin and sample in a tube furnace. This method was proved to be accurate (within 1.5 wt. % deviation) by using burning off data obtained from CF/Epoxy and CF/Vinyl Ester samples. 20% and 30% carbon/PAA samples were burned off and carbon fiber content was obtained using this method. The results of the present study will be helpful in determining the end-user applications of these composite materials. Keywords: Long Carbon Fibers, Elevated Temperature, Mechanical Properties, Burn off Test.

Wang, Qiushi

458

Metal-polymer and polymer-polymer interfaces: Application to conjugated polymer electronic devices  

Microsoft Academic Search

The study of metal-polymer and polymer-polymer interfaces is applied to conjugated polymer electronic devices. Conjugated polymers are a class of organic materials which have metallic or semiconducting properties which are being investigated as alternatives to traditional semiconducting materials. When conjugated polymers are used in devices, the interfaces are found to be critical to device performance. X-ray photoelectron spectroscopy (XPS) and

Julie Anne Osladil Smallfield

2002-01-01

459

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

Code of Federal Regulations, 2010 CFR

...Nitrate *Ethylene-Methacrylic Acid Copolymers *Ethylene-Vinyl Acetate Copolymers *Fatty Acid Resins *Fluorocarbon Polymers...Alpha)Olefins Polyacrylic Acid *Polyamides *Polyarylamides... *Polybutenes Polybutenyl Succinic Anhydride...

2010-07-01

460

Miscibility and phase properties of poly(aryl ether ketone)s with three high temperature all-aromatic thermoplastic polyimides  

Microsoft Academic Search

Several semicrystalline poly(aryl ether ketone)s (PEK, PEEK and different isomers of PEKK) were melt-blended at T > 400°C with three high temperature thermoplastic polyimides. The compatibility and crystallization properties of the blends were studied by differential scanning calorimetry (d.s.c.). Blends of a semicrystalline New-Thermoplastic PolyImide (N-TPI) showed some surprising differences in the fastquenched amorphous samples. Its compatibility could be approximately

Bryan B. Sauer; Benjamin S. Hsiao; Katherine L. Faron

1996-01-01

461

High-Performance Polymers Having Low Melt Viscosities  

NASA Technical Reports Server (NTRS)

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.

Jensen, Brian J.

2005-01-01

462

The role of nanoparticle synergies in modifying the thermal properties of biodegradable polymer blends  

NASA Astrophysics Data System (ADS)

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.

Yang, Kai; He, Shan; Davis, Rachel; Rafailovich, Miriam; Kashiwagi, Takashi

2012-02-01

463

High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations  

NASA Technical Reports Server (NTRS)

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.

Goldberg, Robert K.; Stouffer, Donald C.

1998-01-01

464

Polymer/clay/wood nanocomposites: The effect of incorporation of nanoclay into the wood/polymer composites  

NASA Astrophysics Data System (ADS)

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.

Hetzer, Max E.

465

Diode laser welding for packaging of transparent micro-structured polymer chips  

NASA Astrophysics Data System (ADS)

Laser transmission welding in recent years has been established as a versatile method for interconnection of thermoplastics, at least for macroscopic parts. The technology also offers interesting possibilities for packaging of transparent, micro-structured polymer chips, as used for life science or biotechnology applications. A method for transmission welding, based on a diode laser bar in combination with a thin layer of IR-absorbing dye, is introduced, that allows for fast, mask-less welding of two thermoplastic substrates, at least one of which contains micro structures. The process strongly depends on the ratio of the IR-absorbing dye layer thickness to the depth of the microstructures and should be <<1. Detailed results of the absorption of the dye layers as a function of the spin coating parameters used for preparation of the films are presented, including depth profile analysis. It is demonstrated that the formation of good quality weld seams mainly depends on the energy per unit length coupled to the substrate, which is adjustable by the feed rate and the laser power applied. As an example the process window for welding CGE chips made of PMMA, containing 50 ?m wide and deep channels, separated by 100 ?m wide webs is shown. The applicability of the technology to other polymer chip geometries together with concepts for further improvement is demonstrated.

Klotzbuecher, T.; Letschert, M.; Braune, T.; Drese, K.-S.; Doll, T.

2006-02-01