bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of time and temperature on the mechanical behavior of epoxy composites
Authors: Moehlenpah A. E. , Ishai O. , Dibenedetto A. T. 
Published: December 2004

AbstractA crosslinked epoxy resin consisting of a 60/40 weight ratio of Epon 815 and Versamid 140 and composites of this material with glass beads, unidirectional glass fibers and air (foams) were tested in tension, compression and flexure to determine the effect of time and temperature on the elastic properties, yield properties and modes of failure. Unidirectional continuous fiber‐filled samples were tested at different fiber orientation angles with respect to the stress axis. Strain rates ranged from 10−4 to 10 in./in.‐min and the temperature from −1 to 107°C.Isotherms of tangent modulus versus strain rate were shifted to form master modulus curves. The moduli of the filled composites and the foams were predictable over the entire strain rate range. It was concluded that the time‐temperature shift factors for tangent moduli and the time‐temperature shift factors for stress relaxation were identical and were independent of the type and concentration of filler as well as the mode of loading.The material was found to change from a brittle‐to‐ductile‐to‐rubbery failure mode with the transition temperatures being a function of strain rate, filler content, filler type and fiber orientation angle, indicating that the transition is perhaps dependent on the state of stress.In the ductile region, an approximately linear relationship between yield stress and log strain is evident in all cases. The isotherms of yield stress versus log strain rate were shifted to form a practically linear master plot that can be used to predict the yield stress of the composites at any temperature and strain rate in the ductile region. The time‐temperature shift factors for yielding were found to be independent of the type, concentration and orientation of filler and the mode of loading. Thus, the composite shift factors seem to be a property of the matrix and not dependent on the state of stress. The compressive‐to‐tensile yield stress ratio was practically invariant with strain rate for the unfilled matrix, while fillers and voids raised this ratio and caused it to increase with a decrease in strain rate. The yield strain of the composites is less than the unfilled matrix and is a function of fiber orientation and strain rate.
Cold rolling of polymers. 1 Influence of rolling on properties of amorphous polymer
Authors: Broutman Lawrence J. , Patil R. S. 
Published: December 2004

AbstractStrips of ductile, amorphous thermoplastic polymers such as polycarbonates, acrylonitrile‐butadiene‐styrenes, polysulfones and polyphenylene oxides have been reduced in thickness by passing them through a metalworking rolling mill at room temperature. Properties of the rolled strips were studied as a function of the thickness reduction. In addition to rolling unidirectionally, cross rolling (biaxial rolling) was also studied using equal thickness reductions in each direction. The maximum thickness reduction (to — tf)100/to which could be achieved was approximately 60 per cent regardless of the polymer studied here. Stress‐strain curves, density changes, thermal stability, hardness and Izod impact strengths have been determined as a function of thickness reduction and sheet direction.
The effect of molecular weight and orientation on the sorption of n‐pentane by glassy polystyrene
Authors: Baird B. R. , Hopfenberg H. B. , Stannett V. T. 
Published: December 2004

AbstractThe effects of polymer molecular weight, molecular weight distribution, and orientation on the rate of relaxation‐controlled sorption of n‐pentane by glassy polystyrene were studied. The sorption follows Case II kinetics but for films which sorb slowly the sorption rate increases at relatively long times until sorption is sharply terminated. This rate increase may be explained by the development of dispersed microvoids within the unrelaxed film core. Overshoot of the equilibrium n‐pentane content occurs in sorption experiments in which accelerated sorption is pronounced.The sorption rate is independent of polymer molecular weight and molecular weight distribution per se over a broad wrange of these parameters. Essentially identical vapor sorption kinetics were observed for well annealed polystyrene films of different molecular weights and distributions. Conversely, for vapor sorption by uniaxially oriented films and for liquid sorption by partially annealed films, high molecular weight film (1,880,000) exhibits greater sorption rates than low molecular weight film (ca. 200,000). These differences in rate are not due to molecular weight differences per se, but are a consequence of the dissimilar response of free volume and strain development for films of different molecular weight prepared with a given time‐temperature‐strain history.Crazing of carefully annealed polystyrene films occurs during desorption of n‐pentane from partially saturated films. The depth of craze penetration reflects the point of advance of the discontinuous Case II sorption boundary.
Advances in instrumentation and technique of torsional pendulum and torsional braid analyses
Authors: Gillham J. K. , Roller M. B. 
Published: December 2004

AbstractA torsional pendulum which operates throughout the temperature range — 180° ⇄ +650°C, and permits the examination of specimens which conform to ASTM standard D2236 is reported. The same apparatus is used for torsional braid analyses for which a composite specimen is prepared by impregnating a multifilament glass braid with a solution of polymer and thermally removing the solvent. A linear‐with‐angle no‐drag optical transducer which employs the linear transmission region of a pair of polarizers is described. The apparatus has been used for examining thermo‐hysteresis effects in polymers. Hysteresis can arise in polymers from physical time‐dependent phenomena such as crystallization ⇄ fusion, dry atmosphere ⇄ water vapor, annealing ⇄ cracking, and from chemical reactions. Thermally‐induced chemical reactions can be regulated so as to freeze out preferentially longer range relaxations, thereby extending the glassy state behavior to higher temperatures. A comparison of the thermomechanical behavior of a commercially available polyimide film and of a polyimideforming varnish is reported using torsional pendulum and torsional braid analyses.
The effect of hydrostatic pressure on the tensile properties of plastics
Authors: Pugh H. Ll. D. , Chandler E. F. , Holliday L. , Mann J. 
Published: December 2004

AbstractThe effect of hydrostatic pressure, up to 112,000 lb/in.2, on the tensile properties of four polymers is reported. The pressure soaking of polystyrene in castor oil had no significant effect on the material's residual properties when tested under ambient conditions. When tested under pressure polystyrene necked, like a metal, and exhibited a brittle ductile transition at 40,000 lb/in2. Between 40,000 to 112,000 lb/in.2 the tensile strength increased by about 30%. Young's modulus and yield strength were only slightly affected by pressure. Similar results were obtained for specimens sheathed to prevent possible plasticization of the polystyrene. Polymethylmethacrylate tested at 112,000 lb/in.2 failed just short of its instability point and with only a slight increase in Young's modulus. These amorphous polymers thus behaved under pressure in a generally similar manner to metals.Pressure had a marked effect on the stress‐strain curves of two crystalline polymers polyethylene and nylon. Young's modulus and tensile strength were considerably increased and elongation decreased. Pressure inhibited ‘drawing’ of the materials. Deformation was restricted to a small necked region.
Pressure profiles in plasticating extruders
Authors: Donovan R. C. 
Published: December 2004

AbstractThe pressure distribution through the melting and melt zones of a plasticating extruder is discussed, and an analysis is described for predicting the pressure profile. In the stable melting zone, the pressure profile is calculated based on flow in the melt pool, and the pressure is strongly influenced by the flow of the solid bed of plastic. The solid bed flow is primarily determined by the polymer rigidity in the screw compression section. If the size (through a melting analysis) and the velocity (through a solid bed acceleration parameter) of the solid bed along the screw channel are reasonably approximated, the pressure profile is reasonably approximated by this analysis. Inaccurate representations of the size or velocity of the solid bed can yield inaccurate pressure profile prediction.In the unstable melting region, the assumption of a complete melt yields reasonable pressure predictions. The introduction of these concepts into an extrusion model permits a more accurate prediction of the operating RPM of a given screw design in a given machine.
Plastic deformation of crystalline polymers
Authors: Peterlin A. 
Published: December 2004

AbstractUnder uniaxial tensile load, the plastic deformation of unoriented crystalline polymers first transforms the lamellae into a fibrous structure. Usually the drawing is inhomogeneous with a neck propagating through the sample. The higher the draw ratio, the higher the axial elastic modulus as a consequence of the larger fraction of taut tie molecules in amorphous layers connecting the crystalline blocks of each microfibril. As a consequence of the almost 1/(1 − α) times higher strain of amorphous layers under tensile load, the taut tie molecules are much more strained than the chains in crystal blocks. Hence, their contribution to elastic modulus is substantially higher than one would guess from their fraction β. This is more so in polyethylene with higher crystallinity (α = 0.8) than in nylon 6 with low crystallinity (α = 0.5). Even for the highest modulus polyethylene E = 70 GPa ∼ 0.3 × Ec, one needs less than 7.5 percent of taut tie molecules. The plastic deformation of the fibrous structure markedly enhances the number of interfibrillar tie molecules in nylon 6 and to a lesser extent in polyethylene and polypropylene. Homogeneous drawing without a neck transforms the whole sample into a fibrous structure rather uniformly so that for a long while one has the lamellar and fibrillar morphology side by side. The end effect on the structure obtained does not differ appreciably from inhomogeneous drawing with neck propagation. The drawing of polymers with a liquid crystal structure yields a highly aligned fibrous structure with very few chain folds and an exceptionally high elastic modulus and strength. But the axial connection of individual highly oriented and ordered domains is affected by a relatively small fiaction of tie molecules, and this is responsible for reduction of the elastic modulus below the value of the ideal crystal lattice.
Graft copolymers of polysaccharides with thermoplastic polymers. A new type of filled plastic
Authors: Bagley E. B. , Fanta G. F. , Burr R. C. , Doane W. M. , Russell C. R. 
Published: December 2004

AbstractA series of starch graft copolymers and one cellulose graft copolymer were prepared containing 40‐50 percent synthetic polymer. The monomers used (styrene, methyl methacrylate, methyl acrylate, and butyl acrylate) were chosen to give grafted synthetic polymers with varying glass transition temperatures (Tg). These graft copolymers were extruded, in the absence of any added thermoplastic homopolymer, to give strong, continuous polysaccharide‐filled plastics which are biodegradable and which exhibit little or no die swell. Properties of plastics varied with the Tg of the thermoplastic portion. Starch‐g‐polystyrene and starch‐g‐poly(methyl methacrylate) were hard and brittle, while graft copolymers prepared from methyl and butyl acrylate were more flexible and leathery. The graft Uopolymers with lower Tg grafts required less torque and could be extruded at lower temperatures. In the methyl acrylate series, a graft copolymer prepared from gelatinized starch was more easily extruded than one prepared from granular starch, and addition of water produced a water‐filled extrudate of excellent quality. The surprising feature of these results is that the matrix polymers, starch and cellulose, are rigid, nonsoftening materials. Grafting of a thermoplastic polymer to these matrix polymers would not be expected to give an extrudable product. The results are explained as powder flow followed by fusion or sintering of the graft polymers under the temperature and pressure conditions in the die.
Nylon matting: A textile structure used for soil and civil engineering applications
Authors: Godehn D. J. 
Published: December 2004

AbstractA new type of interlaced mat made of heavy denier nylon monofilaments has been developed, and has been under evaluation for the past few years. Due to its combination of unique properties—high strength, great porosity, chemical stability—it is finding uses in many varied applications. Its current greatest use is in soil erosion control, where the product, when placed on steep banks, traps soil particles caused by runoff water, thus preventing erosion and providing a good seed bed for grasses and other ground cover. Placed under turf and sods, the structure provides a porous, open structure which holds moisture and enhances root growth, while the mechanical strength of this material reduces packing of the soil, thus making a superior base for athletic fields and playgrounds. The product, its properties, and its applications are described.
Static and kinetic studies of polystyrene/poly(vinylmethylether) blends
Authors: Han C. C. , Okada M. , Muroga Y. , Mccrackin F. L. , Bauer B. J. , Tran‐Cong Q. 
Published: December 2004

AbstractA systematic study of static and kinetic phase behavior of deuterated polystyrene/poly(vinylmethylether) blends is presented in this paper. The static properties are studied by the small angle neutron scattering techniques and the kinetics of phase decomposition are studied by the temperature jump light scattering; technique. This procedure provides detailed information about phase behavior with regard to both thermodynamics and kinetics.
Polyethylene‐polycarbonate blends: Interface modification, phase morphology and measurement of orientation development during cast film and tubular extrusion by infrared dichroism
Authors: Endo Shigeru , Min Kyonsuku , White James L. , Kyu Thein 
Published: December 2004

AbstractThe phase morphology and polymer chain orientation in polyethylene‐polycarbonte blends is investigated. A blend with a dispersed polyethylene phase was found to exhibit phase growth under quiescent conditions. Addition of a styrene‐(ethylene/butene) block copolymer controls the phase morphology and prevents phase growth. Melt spun tapes and tubular film have been prepared from polyethylene‐polycarbonate blends. Orientation of the crystallo‐graphic axes of the polyethylene and the chain axis of the polycarbonate were determined by infrared dichroism. The addition of polycarbonate to polyethylene is found to decrease chain orientation at the same drawdown stress.
Phase separation in crosslinked resins containing polymeric modifiers
Authors: Bucknall C. B. , Partridge I. K. 
Published: December 2004

AbstractAn analysis is made of the thermodynamic and kinetic factors affecting phase separation in blends of di‐, tri‐ and tetrafunctional epoxy resins, cured with either diamino‐diphenylsulphone (DOS) or with dicyanodiamide (Dicy), and modified with either poly(ethersulphone) (PES) or carboxyl‐terminated butadiene acrylonitrile (CTBN) rubber. The applicability and limitations of the solubility parameter approach in predicting compatibility in reactive blends are considered.
The effect of rubber particle size on the impact properties of high impact polystyrene (HIPS) blends
Authors: Hobbs S. Y. 
Published: December 2004

AbstractThe impact fracture of nominally identical high impact polystyrene resins having different and well‐characterized rubber particle size distributions is discussed. A numerical model for craze termination is presented and its predictions are compared with experimental data. An alternative explanation for the observed effect of particle size on fracture energy is considered.
Flexural properties of moldings of rigid polyurethane made by reaction injection molding
Authors: Iida Makoto , Gotoh Masao , Yokono Hitoshi , Miyano Yasushi 
Published: December 2004

AbstractFlexural properties of moldings made by Reaction Injection Molding (RIM), which are structural foams consisting of high density skin and low density core, were investigated by three‐point bending tests. Two failure modes were observed in bending tests of the moldings made by RIM, and they are classified as follows according to the density ratio of skin layer to core layer: the opposite side of the skin layer to which load was subjected failed by tensile stress: and the same side of the skin layer to which load was subjected failed by compressive stress, causing wrinkling or buckling. Then the conventional composite beam theory was applied to the former failure mode and Hoff s buckling theory to the latter, and equations were derived to predict the flexural properties of the structural foams, which involved buckling from the flexural properties of solid construction. In addition, it has been shown that there exists a density distribution that maximizes the flexural strength of the moldings made by RIM with a given overall density. The results obtained here should be useful to the optimum structural design of moldings made by RIM.
Surface tension and surface entropy for polymer liquids
Authors: van Ness K. E. 
Published: December 2004

AbstractA cell theory for the prediction of the surface tension of polymer liquids is modified to include an entropic effect due to molecular asymmetry. Also considered is the extent of the effect of the preservation of connectivity in the vicinity of the surface upon the potential energy zero term due to missing nearest neighbors of orders greater than one. Theory and experiment are in good agreement without an adjustable surface parameter.
Arylmethyl sulfones: A new class of photoacid generators
Authors: Novembre A. E. , Hanson J. E. , Kometani J. M. , Tai W. W. , Reichmanis E. , Thompson L. F. , West R. J. 
Published: December 2004

AbstractThe X‐ray and deep UV radiation response is described for resist systems consisting of poly(4‐tert‐butoxycarbonyloxystyrene‐co‐sulfur dioxide) PTBSS combined with an arylmethyl sulfone. A 2:1 4‐tert‐butoxycarbonyloxystyrene (TBS): sulfur dioxide (SO2) resist has been found to function as a highly sensitive, 1.4 nm X‐ray, single‐component, chemically amplified resist. The same resist, however, exhibits reduced sensitivity to 0.8 nm X‐rays and deep UV (248 nm) radiation. Improvement in 0.8 nm X‐ray sensitivity is achieved by the addition of 12 mol% bis(3,4‐dichlorobenzyl) sulfone (DCBS) to the 2:1 TBS:SO2 resist. For this two‐component resist formulation, the 0.8 nm X‐ray sensitive improved from >375 to 125 mJ/cm2. Similarly, the sensitivity of the 3:1 TBS:SO2 copolymer to deep UV radiation improves to 40 mJ/cm2 with addition of 10 mol% DCBS. Sulfones, such as DCBS, provide two‐component resist formulations capable of <0.5 μm resolution.
Liquid crystallinity: Medium effects on photopolymerization rates
Authors: Hoyle C. E. , Kang D. , Chawla C. P. , Griffin A. C. 
Published: December 2004

AbstractOrdering of the medium in which free radical polymerization is conducted can, under appropriate circumstances, alter the kinetics of the chain‐growth process, resulting in enhanced rates. Since in many systems medium changes occur at higher conversion, it is important to take into account any alterations in the polymerization rate induced by such phenomena. We have found that exotherms initiated by individual laser pulses can be useful in identifying and providing detailed information concerning rate acceleration in liquid crystalline systems. From measurements of the pulse intensities in the sample cell, estimates of the quantum efficiency and kinetic chain length have been made directly from the integrated areas of the exotherm curves. Recent refinements in our sample geometry have allowed us to generate reproducible efficient data as a function of the degree of conversion and order in the polymerization medium.
Novolak design concept for high performance positive photoresists
Authors: Hanabata Makoto , Oi Fumio , Furuta Akihiro 
Published: December 2004

AbstractNovolak resins have been optimized for high performance positive photoresists. Low molecular weight novolak resins are the key components for improving resolution capability, sensitivity, and heat resistance of positive photoresists. Various phenolic compounds (monomers) and oligomers of metacresol novolak resins were evaluated as low molecular weight components. It was found that phenolic compounds that have moderate hydrophobicity and azocoupling capability with diazonaphthaoquinone compounds greatly improve positive photoresist performance. This is explained in terms of the Stone wall model for positive photoresist development.
The synthesis and characterization of novel 2‐nitrobenzyl sulfonate photo‐generators of acid
Authors: Houlihan F. M. , Neenan T. X. , Chin E. , Reichmanis E. , Kometani J. M. 
Published: December 2004

AbstractMethodology was developed for the synthesis of novel 2‐substituted o‐nitrobenzyl chromophores, which were derivatized as the tosylate esters. The thermal stabilities of these new tosylates fell within the range predicted from an empirical model. Lithographic sensitivities of deep UV resists made from these new esters and poly(4‐(tert‐butoxycarbonyloxy)styrene‐sulfone) ranged from 45 to 90 mJ/cm2.
Conducting polymers as lithographic materials
Authors: Angelopoulos Marie , Shaw Jane M. , Lee Kam‐Leung , Huang Wu‐Song , Lecorre Marie‐Annick , Tissier Michel 
Published: December 2004

AbstractConducting polyaniline is found to be suitable for several lithographic applications. With the use of onium salts, polyaniline is made radiation sensitive and shown to be a high resolution conducting photo and electron‐beam resist. Conducting lines of 0.25 μm have been patterned with e‐beam irradiation. Thin films of conducting polyaniline are found to be effective discharge layers for e‐beam lithography. Insulating resist systems charge during e‐beam exposure, which results in pattern displacements. When polyaniline is used as a conducting layer below the imaging resist, no pattern displacements are observed. Polyaniline is also shown to eliminate charging during the high resolution inspection and dimensional measurements of X‐ray and optical masks by scanning electron microscopy (SEM) when used as a coating on top of the mask. In addition, polyaniline can be used for electrolytic and electroless type metallization processes.