bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frictional behavior of solid polymers on a metal surface at processing conditions
Authors: Chung C. I. , Hennessey W. J. , Tusim M. H. 
Published: December 2004

AbstractThe frictional coefficients of three glassy polymers (polystyrene, polycarbonate, and polymethylmethacrylate) and three crystalline polymers (high density polyethylene, low density polyethylene and polypropylene) on a highly polished steel surface were measured at high temperatures, high pressures, and high speeds, all comparable to actual processing conditions. The frictional behavior of these polymers was found to depend on temperature, pressure‐and speed in a very complicated manner. There appears to exist inter‐relationships among the temperature, pressure and speed dependences of the frictional coefficients. The frictional coefficients of ductile, crystalline polymers as a function of temperature appear to undergo two distinct transitions: one associated with yielding and the other associated with melting. The frictional coefficients of glassy polymers go through only one transition, associated with the glass transition. The friction‐generated heat at high pressures and high speeds can increase the sliding interface temperature of a polymer to values much greater than the metal surface temperature, and thus the polymer can start to melt (or plasticate) at metal surface temperatures appreciably below its thermodynamic melting (or glass transition) temperature.
Polymeric adsorbents for treatment of waste effluents
Authors: Kunin Robert 
Published: December 2004

AbstractA significant advance in ion exchange resin and adsorbent technology has been the development of the macroreticular pore structure. Synthetic rotes have been developed for preparing both ion exchange resins and polymeric adsorbents of high surface area and pore volume. Syntheses have been developed to the degree that the surface area and pore.parameters can be widely varied. Several of these macroreticular polymers based upon the crosslinked styrene and acrylate systems are now available commercially. These polymeric adsorbents are hard, durable, insoluble spheres of high surface area and porosity. They are available in a variety of polarities. The nonpolar adsorbents are particularly effective for adsorbing nonpolar solutes from polar solvents. Conversely, the polar adsorbents are very effective for adsorbing polar solutes from nonpolar solvents. Of particular interest is the use of these polymeric adsorbents for the treatment of effluent wastes. In some cases it has been demonstrated that one can recover significant quantities of re‐usable chemicals that more than pay for the waste, treatment. The use of the polymeric adsorbents for the treatment of phenolicwastes is an example. Other related applications include the removal of chlorinated pesticides, TNT residues, and other noxious compounds from waste effluents and water supplies.
Solubility of supercritical gases in polymers—a review
Authors: Bonner David C. 
Published: December 2004

AbstractProcessing of polymers is greatly affected by the presence of dissolved gases. Analysis of the effect of dissolved gases requires two types of information: equilibrium thermodynamic data and predictive correlations as well as diffusion rate data and analyses. We review here the state‐of‐the‐art knowledge of the equilibrium thermodynamics of gases dissolved in polymers. The published data are presented and analyzed. Also, we review the latcst theories and predictive correlations for gas solubility in polymers.
Transition behavior and phase segregation in TDI polyurethanes
Authors: Schneider N. S. , Sung C. S. Paik 
Published: December 2004

AbstractPrior studies of two series of segmented polyurethanes based on 2, 4 toluene cliisocyanate (2, 4 TDI) or 2, 8 TDI, butanediol, and a 1000 molecular weight polytetramethyleneoxide (PTMO‐1000) soft segment revealed a rapid increase in soft segment glass transition temperature (Tg) with increasing urethane content in the 2, 4 TDI series. The change in Tg couldbe correlated with estimates of hard segment‐soft segment phase mixing obtained by infrared analysis of the urethane NH and carbonyl bands. In the present paper, the infrared data have been reevaluated using improved procedures for resolving the carbonyl band into H‐bonded and nonbonded components, and the relation between the estimated extent of phase mixing and Tg has been reexamined. The transition behavior in an extensive series of related polymers has also been determined, including 2, 4 TDI arid 2, 6 TDI samples with PTMO2000 as well as polybutyleneadipate (PBA‐1000 and PBA‐2000) soft segments. The results indicate the effectiveness, of increased soft segment molecular weight in promoting phase segregation, imply that much greater phase mixing occurs in polyester than polyether samples, suggest that anchoring the ends of the soft segments has only a small effect on Tg, and provide some evidence that H‐bonding not only increases Tg but can also impede soft segment crystallization.
A water‐soluble, reciprocity‐law‐failing photoresist
Authors: Akagi Motoo , Nonogaki Saburo , Kohashi Takahiro , Oba Yoichi , Oikawa Mitsuru , Tomita Yoshifumi 
Published: December 2004

AbstractFor the purpose of obtaining a water‐soluble, reciprocity‐law‐failing photoresist, a study was made on the photo‐crosslinking properties of various systems composed of water‐soluble polymers and bisazides. Reciprocity‐law‐failing photoresists are suitable for use in the fabrication of black matrix color picture tubes without any alteration in the shadow mask. As a result, a system containing polyvinylpyrrolidone, polyacrylamide, and 4, 4′‐diazidostilbene‐2, 2′‐disulfonic acid disodium salt was found to show a significant reciprocity‐law‐failing property in the range of light intensity used practically in black matrix fabrication. The mechanism of the photo‐cresslinking reaction of this photoresist was investigated. It is suggested that the bisazide decomposes to liberate a reactive dinitrene intermediate. This photodecomposition was found to proceed reciprocally. The nitrene reacts with polymer molecules to form a water‐insoluble three dimensional network. If, however, oxygen is present, this crosslinking reaction is inhibited by a preferential reaction between dinitrene and oxygen. By this oxygen effect, this photoresist reveals significant reciprocity‐law‐failing characteristics.
Three dimensional behavior of negative electron resists
Authors: Heidenreich R. D. , Kammlott G. W. 
Published: December 2004

AbstractIt is illustrated experimentally that swelling and deformation of narrow lines (width < 1 μm) is an important limitation on the fidelity and transverse resolution of negative electron resists. The thickness response curve developed for negative resists is discussed and the effect of feature size is introduced through the experimental parameter D, the rigid gel dose, or the dose required to initiate a free standing line of width < 0.2 μm. The transition from line to area exposure is discussed and the effect of substrate backscatter or transverse resolution in gratings is calculated. The observed resolution is 3‐5 times the calculated value from swelling and deformation during development.
Line‐Profile resist development simulation techniques
Authors: Jewett R. E. , Hagouel P. I. , Neureuther A. R. , Van Duzer T. 
Published: December 2004

AbstractThe relative advantages and disadvantages of three different algorithms are compared for simulating the time evolution of two‐dimensional line‐edge profiles produced by a locally rate dependent surface etching phenomenon. Simulated profiles typical of optical projection printing and electron‐beam and X‐ray lithography of micron‐sized lines in resist and etching of ion‐implanted SiO2 are used as a basis of comparison. One of the algorithms is a cell‐by‐cell removal model used earlier by Neureuther and Dill. One of the newly developed algorithms employs ray tracing; it can be shown that the path followed by a point on a front between the developed and undeveloped regions can be calculated using ray‐optic equations. The other new algorithm uses a string of points initially on the surface of the exposed resist. The points on the string advance perpendicular to the local direction of the string; with time the string of points moves down into the resist, replicating the action of a developer. We compare the computing cost, convenience, and accuracy of the algorithms.
X‐ray lithography
Authors: Feder R. , Spiller E. , Topalian J. 
Published: December 2004

AbstractThe advent of X‐ray lithography as a natural compliment to electron beam pattern generation and photolithography seems to be filling a need in the fabrication of submicron devices. The X‐ray technique, which is simple for single level devices, lags behind other lithographies in registration techniques. However, its proven high resolution capabilities is responsible for the increased interest in further development. At present a, variety of mask substrates are being evaluated with no one material exhibiting an overwhelming advantage. The type of substrate used is closely coupled to the permissable wavelength of the X‐ray source. The X‐rays used for lithography to date vary from Rh L (4Å) up to CK (44Å). Each wavelength shows a distinct advantage and disadvantage. For example, at short wavelengths substrates can be relatively massive but resists are less sensitive and high resolution masks have low contrasts. At longer wavelengths, resists are more sensitive and masks have higher contrast, but defects due to dust are more probable. The use of more than one X‐ray source could fulfill the requirements imposed by mask making and device fabrication. High throughput for both masks and device require both foster resists and higher intensity X‐ray sources.
Differential dissolution and electron‐beam lithographic sensitivity of poly(methyl methacrylate)
Authors: Helbert J. N. , Cook C. F. , Poindexter E. H. , Wagner B. E. 
Published: December 2004

AbstractPhotolithographic and electron‐beam integrated circuit fabrication techniques rely heavily upon differences in polymer resist dissolution (development) rates to produce circuit patterns. We have applied the wide‐line NMR, technique, augmented by dynamic nuclear polarization, to the measurement of polymer dissolution rates of poly(methyl methacrylate), (PMMA). At high gamma‐ray exposures, we find PMMA to have dissolution rates from 2X to 1000X those of unirradiated material. The highest radiation‐enhanced dissolution rates are obtained with carbon tetrachloride‐based developer solutions, whereas generally lower enhanced rates are observed with 1:3 acetone or methylethylketone/isopropanol standard developer. E‐beam line exposures are developed in PMMA and poly(ethyl methacrylate), PEMA, resists using similar developers for comparison. Using straight CCl4 as a developer, e‐beam lines 1‐2 μ wide were developed in 3800 Å thick PEMA resist at 1 × 10−5 C/cm2 with ≤200 Å loss in unexposed resist thickness. The higher differential dissolution with CCl4, a poorer solvent for unirradiated PMMA than acetone or MEK, is explained by decline in polarity of PMMA by radiationinduced decarboxylation.
Oligomeric fluorinated additives as surface modifiers for solid polymers
Authors: Berneit Marianne K. 
Published: December 2004

AbstractSuccessful modification of the surface properties of solid polymers was obtained by the adsorption of appropriate partially fluorinated oligomers at polymer/air and polymer/substrate inter faces during the formation of these interfaces. These additives, in concentrations of 0.25 percent, effectively lowered the critical surface tension of wetting, γc, of such polymers as polystyrene, poly(methylmethacrylate), and poly(vinylidene chloride) copolymers by as much as 26 dyn/cm. The obtained low γc values of 14 dyn/cm correspond to surfaces containing closely packed CF3 and CF2 groups. Adhesion of additive‐containing polymer films to various substrates was demonstrated to be a function of additive diffusion to the polymer/substrate interface, its subsequent adsorption and molecular orientation at that interface, and the surface energy of the substrate. The fluorinated additive molecules also have the advantage of being sufficiently mobile in the solidified polymer to reach and repair the interfaces.
The role of the interface in adhesion phenomena
Authors: Mittal K. L. 
Published: December 2004

AbstractThe role of the interface in adherend‐adherate combinations and in the strength of adhesive joints has been examined. For the former systems, practical adhesion (as determined experimentally, for example, by peel, tensile, or shear strengths) is a function of basic adhesion (determined by intermolecular, interactions such as van der Waals, electrostatic, or valence type forces) and many other factors. Adhesive joint strength depends pends upon the mechanical response of the various phases involved; however, the data in the literature on such strengths suggest the importance of surface chemical and energetic factors. Various such criteria, including, wetting, thermodynamic work of adhesion WA, and interfacial tension, ySL, for maximum joint strengths and the conditions which optimize these criteria are discussed. The testing of these factors against the literature data on adhesive joint strengths shows that the interfacial tension between the substrate and the adhesive (ysL) is the most important criterion; the lower the ySL, the higher the joint strength. In the case of adherend‐adherate systems, (e.g., metallized polymers), basic adhesion can be improved by chemical bonding or electrostatic contributions, and this improvement may or may not be reflected in improved practical adhesion. Examples are cited where an increase in basic adhesion does culminate in improved practical adhesion. On the other hand, practical adhesion does not always correlate with basic adhesion due to the influence of other factors.
Structure and properties of microcomposites and macrocomposites from block polymers
Authors: Aggarwal S. L. , Livigni R. A. 
Published: December 2004

AbstractThe incorporation of a rubber phase in glassy polymers, as is well known in the case of high impact polystyrene, leads‐to an increase in their impact strength. Block polymers offer three principal approaches for obtaining multiphase glassy polymers in which an elastorner phase is present in the matrix of the glassy polymer. They are: (1) control ofblock polymer composition, (2) blending of block polymer with homopolymers, and (3) polymerization of a solution.of a block polymer in the monomer corresponding to one of the blocks. The observed properties, such as impact strength, modulus, and heat distortion temperature, desired in rubber modified glassy polymers are discussed for block polymer systems prepared using the above approaches.
Structure of AB block copolymers with a polypeptide block: Effect of the chain conformation
Authors: Douy André , Gallot Bernard 
Published: December 2004

AbstractThe structure of AB copolymers with a polypeptide block has been studied by X‐ray diffraction, electron microscopy, infrared spectroscopy, and circular dichroism. Copolymers with a polyvinyl block (polybutadiene or polystyrene) and a hydrophobic polypeptide block (polybenzyl‐L‐glutamate or polycarbobenzoxy‐L‐lysine) exhibit a lamellar structure in the dry state and in solution in dioxane or in different chlorinated solvents. This lamellar structure consists of plane, parallel, equidistant sheets. Each sheet results from the superposition of two layers: one formed by the polyvinyl chains in amore or less random coil conformation, the other formed by the polypeptide chains in an α‐helix conformation, arranged in a hexagonal array and generally folded. Copolymers with a polyvinyl block and a hydrophilic polypeptide block (poly‐Llysine or poly‐L‐glutamic acid) exhibit a larnellar structure in water solution and in the dry state. The difference between this lamellar structure and the preceding one consists in the conformation of the polypeptide chains: an intramolecular mixture of coiled chains, α‐helices, and β chains. Copolymers with a polysaccharide block and a hydrophobic polypeptide block exhibit in DMSO solution and in the dry state a lamellar structure similar to that of copolymers with a polyvinyl block and a hydrophobic polypeptide block.
Thermodynamics of plasticized triblock copolymers. Part II: Model verification by light transmittance and rheology
Authors: Pico Efrain R. , Williams Michael C. 
Published: December 2004

AbstractAn earlier paper proposed a theoretical model for the thermodynamics of microphase separation in a plasticized triblock copolymer. Data on laser light transmission through plasticized films and on dynamic viscosity: of these films are presented in support of model predictions. Two styrenebutadiene‐styrene copolymers were tested: Kraton 1101 with block weights (12.5‐75‐12.5) × 103 and TR‐41‐1467 with weights (9.6‐47.5‐9.4) × 103 using the solvent dipentene (p‐mentha 1, 8 diene), which is favorable for both blocks. The role of such solvents is to depress the temperature of microphase separation, Ts. Optical and rheological measurements of Ts agreed with each other arid, in most cases, with the theory; discrepancies with theory were noted only when Ts was less than Ts for polystyrene. These data along with electron microscopy also support the prediction that the favored morphology for these systems is a mixture of planar and inverted (middle‐block) cylinders and spheres.
Statistical thermodynamics of microdomain structures in block copolymer systems
Authors: Helfand Eugene , Wasserman Z. R. 
Published: December 2004

AbstractA statistical thermodynamic theory of the microdomain structure of block copolymers is presented in qualitative physical terms. Special emphasis is placed on a presentation of the final algebraic formula which may be used to determine lamellar domain sizes as a function of block length and physical parameters. Calculations on lamellar domains and preliminary results for spherical domains are compared with experiments. Other topics discussed are: width of the interphases, results of a more exact theory, and thermodynamic., stability of the domain structure.
Monte Carlo studies of isolated AB block copolymer molecules
Authors: Bendler John , Šolc Karel 
Published: December 2004

AbstractRecent theoretical progress in understanding conformations of AB block copolymer molecules in dilute solution is reviewed. The results of the authors' own biellipsoidal smooth density model (BEM) are compared to the findings recently reported by two independent groups, for the more rigorous self‐avoiding walk models with nearest neighbor interactions (SAW). The SAW results confirm the BEM conclusions for the size and shape behavior of individual blocks under changing solvent‐temperature conditions. The relative orientation and separation of the blocks depend strongly, on the magnitude of AB interactions, while the individual, block parameters are much less sensitive in this respect. Parfial segregation (or partial block mixing) is the general rule rather than the exception, and is aided by the low polymer concentrations which are, found in the overlap region in dilute solutions. A unified view of homopolymers and block copolymers emerges from these models, with homopolymers being a special case of the latter group. Inherent to BEM is the arrowhead‐like overall shape of the molecules, which appears to survive under most conditions.
Emulsifying properties, of block copolymers. Oil‐water emulsions and microemulsions
Authors: Riess G. , Nervo J. , Rogez D. 
Published: December 2004

AbstractThe emulsifying effect of poly(styrene‐b‐ethylene oxide) block copolymers (Cop PS‐PEO) has been studied for the toluene‐water system as a function of the molecular characteristics of the copolymer (composition, molecular weight, and structure). To demonstrate the surfactive properties of Cop PS‐PEO, we determined the interfacial tension γi for the toluene‐water system in the presence of these block copolymers. For oil/water (O/W) and water/oil (W/O) emulsions, prepared in the presence of Cop PS‐PEO, we determined the phase inversion point, the particle size of the dispersed phase, the stability and the viscosity as a function of the PEO content, the molecular weight, and the structure of the block copolymers. It appeared that the best results for the emulsification are obtained with Cop PS‐PEO having molecular weights less than 100, 000. Stable O/W emulsions of small particle size are preferentially prepared with di‐ or triblock copolymers having a PEO content of 60‐80 percent. In contrast, stable W/O emulsions are obtained with diblock copolymers having a PS content of 60‐80 percent. The difference in behavior between diand triblock copolymers also showed the importance of the chain conformation at the toluene‐water interface. As an extension, we have shown that microemulsions can be obtained with such polymeric surfactants. Isopropanol and butylamine appeared to be efficient cosurfactants for the system water/toluene/Cop PS‐PEO.
Some comments on post extrusion swelling phenomena: Die entrance or die passage
Authors: Chapoy L. L. , Pedersen S. 
Published: December 2004

AbstractThe mechanistic origins of the post extrusion swelling phenomenon have been the subject of considerable debate. Conflicting theories have postulated that it is caused either by (1) deformations at the die entrance which are recovered upon die exit as a consequence of viscoelastic memory or (2) elastic enorgy, which is stored during capillary flow by the action of normal stress, and subsequently released upon die exit or by both (1) and (2). We have described these situations by mathematical models and show that the resulting equations are similar despite different origins. The difficulties in interpreting the results mechanistically are discussed. Empirically, the results can be described as being exponential in capillary residence irrespective of cause.
A study of the flow properties of rubbers using the rheometrics mechanical spectrometer
Authors: Mukherjee Debi P. 
Published: December 2004

AbstractThe dynamic shear properties of a natural rubber and several commercial synthetic polyisoprenes were measured in a Rheometrics mechanical spectrometer. The dynamic viscosity vs angular velocity curve was fitted to the three‐constant Car, reau model. The rheological parameters were correlated with molecular characteristics such as gel content and weight average molecular weight. The viscosity measurements at high shear rate were obtained from capillary rheometry. The viscosity vs shear rate curve at the low shear rate end was found to be superimposible on the plot of dynamic shear viscosity vs twice the angular velocity.
Viscoelastic parameters of characterized branched polyethylenes
Authors: Ram Arie 
Published: December 2004

AbstractCertain steady state viscoelastic parameters, including melt viscosities, normal stress coefficients, and shear compliances, are determined for a series of well‐characterized low, density polyethylene samples, and the results are analyzed. The effects of shear rate, temperature, molecular weight, molecular weight distribution, and the degree of long chain branching are demonstrated. The agreement observed between steady state shear compliance values derived from normal stresses and those obtained from die swell measurements is significant.
Swelling and hygroelasticiiy of polymeric composites
Authors: Marom Gad 
Published: December 2004

AbstractInvestigated are the swelling and hygroelasticity of a unidirectional glass fiber‐reinforced epoxy composite subjected to boiling water for 24 hrs. By analogy with thermoelasticity, a coefficient of hygroelasticity is defined and shown to be predictable from the coefficients of the constituent materials by Schapery's equations. A mechanism for water penetration into the composite which combines capillarity and diffusion is proposed on the basis of the results of the water take‐up as a function of the composite specimen width (fiber length).