bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of lubricants for polyvinyl chloride
Authors: King L. F. , Noël F. 
Published: December 2004

AbstractThe proper use of lubricants and other additives in the compounding of PVC is hampered by lack of knowledge of their interactions with the polymer. Differential scanning calorimetry has been applied to measure the effect of ingredients on the glass transition temperature of PVC. An interaction parameter, based on changes in the glass transition temperature, has been proposed which quantitatively defines the degree of compatibility and which relates to the more empirical definition of lubricants as internal or external. This study of the compatibility of compounding ingredients as a function of molecular weight and chemical structure provides fundamental information of value in formulating, compounding and processing of PVC.
The potential for reuse of plastics recovered from solid wastes
Authors: Paul D. R. , Vinson C. E. , Locke C. E. 
Published: December 2004

AbstractPlastics in solid wastes is a problem of growing concern. Recycling of wastes is currently believed to be the most acceptable form of disposal in the long run; however, this route is known to be especially difficult for plastics. Recycling would be easier if the various generic types present in solid wastes, mainly polyethylene, polystyrene and poly (vinyl chloride), could be isolated; however, this would be very difficult and expensive. This is a first report on research aimed at evaluating the potential of recycling plastics as a polymer blend of the various generic types. This approach suffers from the difficulty that the different plastics are incompatible and the blend has poor mechanical properties. The extent of this problem is documented with data on many ternary blends employing virgin polyethylene, polystyrene and poly (vinyl chloride) of numerous grades likely to be found in solid wastes. Property degradation was found to be more severe as the complexity of the blend increased, indicating that general municipal wastes could be reused only in very low grade applications, whereas certain commercial wastes might have brighter prospects. Strategies for improving blend properties are outlined.
Polyisocyanurate foams
Authors: Einhorn I. N. , Seader J. D. , Drake W. O. , Mihlfeith C. M. , Kanakia M. D. 
Published: December 2004

AbstractAn experimental program was conducted to study the thermochemical and flammability characteristics of an improved polyisocyanurate foam, uncoated and coated either with fluorinated copolymer or an intumescent material. Testing methods included thermal analysis; scanning electron microscopy; infrared photography; infrared spectroscopy; HLT‐15, ASTM D‐1692, Bureau of Mines Penetration, and XP‐2 smoke chamber flammability tests; limiting oxygen index (LOI); and a moderate‐scale fire simulation test. The uncoated and coated foams were found to have excellent flammability and insulation characteristics, although smoke development was substantial.
Positive and negative photoresist applications of thin films surface‐photopolymerized from hexachlorobutadiene
Authors: Kunz C. O. , Long P. C. , Wright A. N. 
Published: December 2004

AbstractPolymeric films deposited from the vapor of C4Cl6 by the surface‐photopolymerization technique are electrically and mechanically continuous on various substrates when very thin. The thickness of the films depends upon irradiation time with wavelengths in the region 2000‐3000Å. Re‐irradiation in oxygen (air) of the polymeric films with light of these low wavelengths leads to patterned removal of the films. Since films 500Å thick and less can resist etchants for various substrates, a new and extremely thin positive photoresist system is possible. Resolution of etched substrates to lines a few microns wide has been demonstrated. If the polymeric films from C4Cl6 are deposited from the monomeric vapor at lower substrate temperatures they are soluble in various solvents. Re‐irradiation with UV light with the films in vacuum produces a patterned fixing of the polymer with respect to acetone. A negative photoresist system is therefore possible. Again, films of thickness 500Å and less can resist various etchants such that substrates can be etched to high resolution.
Stability of fiber spinning of power‐law fluids
Authors: Shah Y. T. , Pearson J. R. A. 
Published: December 2004

AbstractA stability analysis of fiber spinning of isothermal power‐law fluids has been carried out. The analysis for purely viscous fluids indicates that the critical extension ratio increases with an increase in power‐law constant q above 1. For q greater than approximately 1.5, very high values of critical extension ratio are obtained. A stability analysis in the presence of viscous and inertial forces indicates that for q > 1 critical extension ratio can be correlated to a quantity Rq = q − 1 + 3Re, wherein Re is the Reynolds number. For the values of Rq greather than approximately 0.5, very high values of critical extension ratios are obtained.
Thermal transport in the contact melting of solids
Authors: Griffin O. M. 
Published: December 2004

AbstractMany industrial processes require that solids be transformed to the molten state, thus accurate correlations of heat transfer and melting rates are important in process design. The heat‐balance integral type of analysis is applied here to melter systems where phase change and convection effects are of equal importance, and the appropriate parameters that govern the thermal transport process are presented. Applications of the results to both Newtonian and non‐Newtonian, power‐law melts are discussed, and extensions to variable property situations are outlined. Although the results herein are directly applicable to contact melting systems, the governing parameters are useful in the correlation of other melting processes as well. Acomparison is made between the theory and some experimental data for a gravity‐feed contact melter. The results are directly applicable in practice to the melting of bulk and granular crystalline polymers on melting grids, tube bundles, and plates.
Cold rolled ABS. Part 2: Rubber morphology and tensile properties of hot stretched and cold rolled ABS
Authors: Grancio M. R. , Bibeau A. A. , Claver G. C. 
Published: December 2004

AbstractCold rolling and hot stretching (105°C) both lead to increased failure stress and decreased stress whitening in model ABS composites while hot stretched samples alone retain a tensile yield dip. Further differences between hot stretching and cold rolling are revealed in electron micrographs obtained by the Kato method. In the hot stretched samples the ruber particles appear as elongated “cigar‐like” smooth ellipsoids which reflect the observed macroscopic orientation. SAN occlusions within the ruber particles are deformed to the same degree as the rubber. Ruber particles in cold rolled samples, however, exhibit a jagged, “hairy” surface indicating a high degree of shear distortion; and SAN occlusions within the rubber particles are not deformed in rolling. The rubber particles in cold rolled ABS are flattened and disk‐like rather than ellipsoidal.
Kinetics of the thermal degradation of poly(1,4‐cyclohexylenedimethylene terephthalate)
Authors: Gregory D. R. , Watson M. T. 
Published: December 2004

AbstractThe kinetics for the thermal degradation of poly (1,4‐cyclohexylenedimethylene terephthalate) (PCHDT) were evaluated by means of a melt extruder. The effects of temperature, residence time, and oxygen content of the gas blanketing the polymer during storage on degradation of PCHDT were determined. The rate of thermal degradation was measured in terms of the rate of decrease of inherent viscosity and the rate of increase of carboxyl end group concentration.Residence time, temperature, and their interaction all contributed significantly to the degradation. For the conditions investigated, the oxygen content of the blanketing gas had no measurable effect on degradation. Analysis of the kinetic data yielded equations based on a random chain scission mechanism. These equations enabled the prediction of inherent viscosity and carboxyl end group concentration as functions of temperature and residence time and the inherent viscosity and carboxyl end group concentration of the original polymer. The activation energies for decrease in inherent viscosity and increase in carboxyl end group concentration of poly (1,4‐cyclohexylenedimethylene terephthalate) were determined as 38.7 kcal/mole, respectively.
The effect of light on some commercially important polymers
Authors: Wiles D. M. 
Published: December 2004

AbstractMost organic polymers are damaged by exposure to terrestrial sunlight and eventually the useful properties are lost. Once absorbed, radiation in the erythmal region of the solar spectrum has sufficient energy to cause the rupture of polymer chain bonds.It can be difficult to identify the important chromophores in a polymer system and even more difficult to determine precisely what happens to them following electronic excitation. The number of chemical events leading to the mechanical failure of a plastic can be remarkably small although the variety of them is potentially large.Polypropylene is discussed as an example of a thermoplastic which invariably contains small amounts of light‐absorbing impurities and which, if unprotected, is highly susceptible to photo‐oxidation. Polyethylene terephthalate is used to illustrate a class of polymers which is susceptible to actinic deterioration owing to chromophores in the repeating unit. The primary photochemical reactions occurring in these two systems are described, with improved methods for UV stabilization in mind.
Vapor sorption and liquid interactions with glassy polyblends of polystyrene and poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Jacques C. H. M. , Hopfenberg H. B. , Stannett V. 
Published: December 2004

AbstractPolystyrene, poly(phenylene oxide), and solution‐cast blends of the parent homopolymers were exposed to normal hexane in the liquid and vapor phase. The kinetics of absorption and desorption, the sorption equilibria, and the kinetics of morphological changes were studied as a function of temperature and blend composition.Absorption kinetics of n‐hexane vapor in all blends were largely controlled by polymer relaxations. The sorption rates from the vapor phase varied monotonically with blend composition and increased over a range of four orders of magnitude with increasing poly(phenylene oxide) content. The equilibrium n‐hexane content similarly increased monotonically with poly(phenylene oxide) content although the increase was only by a factor of two over the entire range of compositions. These results were interpreted in light of and were completely consistent with earlier findings with pure polystyrene homopolymer.Films immersed in liquid n‐hexane produced a white, opaque outer shell surrounding an essentially unaffected central core. The kinetics of this whitening process were much more rapid for each of the homopolymers than the kinetics characterizing morphological changes in the blends. These data suggest that film whitening is caused by crazing in the polystyrene‐rich samples and that solvent‐induced crystallization is involved in the whitening of the poly (phenylene oxide) rich material.
Implications of extensional flows in polymer fabrication processes
Authors: Denson C. D. 
Published: December 2004

AbstractThe various types of extensional flows and extensional viscosities are defined and methods of measurement discussed. The role that each of these extensional viscosities plays in various polymer fabrication processes is discussed with examples. Finally, it is shown how engineering analyses of these complex flow fields are conducted using simplified phenomenological equations for the rheological behavior. This approach is recommended for use until such time as tensorially correct, mathematically tractable constitutive equations that are based on molecular theory are available.
Comparison between some empirical equations of state for polymers
Authors: Kamal Musa R. , Levan N. T. 
Published: December 2004

AbstractSome commonly used empirical equations of state for polymers are considered: the Spencer‐Gilmore equation with two and three adjustable parameters, the Whitaker‐Griskey equation, and the Rehage‐Breuer equation. Also, a new equation is proposed: the Inverse Volume equation. These equations are evaluated with regard to fitting experimental P‐V‐T data and agreement with experimental data on isothermal compressibility and thermal expansion coefficient. The adjustable parameters for each equation are determined with the help of Rosenbrock's optimum‐seeking technique. Analysis of the residuals on specific volume for a variety of materials suggests that the Spencer‐Gilmore equation with three adjustable parameters, the Rehage‐Breuer and the Inverse Volume equations yield the smallest and most random residuals and thus the least systematic error. The same three equations mentioned above yield results in good agreement with experimental isothermal compressibility data. However, among all the equations considered in this study, the Inverse Volume equation yields the best agreement with experimental thermal expansion coefficient data. Furthermore, it is the only equation to correctly predict the rise in thermal expansion coefficient with increasing temperature.
Reflectivity of iridescent coextruded multilayered plastic films
Authors: Radford J. A. , Alfrey T. , Schrenk W. J. 
Published: December 2004

AbstractCoextruded plastic films containing 231 alternating layers of polystyrene and polymethylmethacrylate have been made with individual layer thickness in the range of .06–0.1μ. Due to the difference in refractive indices these unique films can be made to reflect portions of the visible spectrum, yielding a highly iridescent appearance.Reflectivity measured on films of known layer thickness distribution correlated with values predicted from optical theory.
An introduction to blood compatible polymer surfaces for use in artificial internal organs
Authors: Olsen Douglas A. , Kletschka Harold D. , Rafferty Edson H. 
Published: December 2004

AbstractWhile the body is a hostile environment for all types of polymers, an even more serious problem is that of thrombus formation induced by all foreign surfaces, including polymeric surfaces. This is a still largely unsolved problem which hinders the development of artificial internal organs. The thromboresistant materials presently proposed and used in artificial organs include heparinized surfaces and materials found to be thromboresistant in certain implantation cites. In this article tissue‐polymer interactions are first discussed and then followed by a discussion of blood‐polymer interactions. The mechanism of thrombus formation is presented and some of the possible interactions of blood with surfaces are suggested. Representative nonthrombogenic and thromboresistant materials are discussed.
Heat transfer to flowing thermally softened polymers
Authors: Griskey Richard G. , Choi Min H. , Siskovic Nandor 
Published: December 2004

AbstractHeat transfer to a flowing thermally softened polymer (polymethylmethacrylate) has been studied. Experimental temperature profiles were determined at various axial lengths. The data are both precise and reproducible. Sizeable viscous dissipation was found to occur. This effect was found to be greater for polymethylmethacrylate than a molten polymer (polyethylene). Cooling as well as heating data were found in this work. The experimentally determined data checked qualitatively with the data computed from a prior analytical solution of the equations of motion and energy.
Development of stress‐crystallized morphology during melt‐spinning of polypropylene fibers
Authors: Fung P. Y.‐F. , Orlando E. , Carr S. H. 
Published: December 2004

AbstractMelt‐spinning of isotactic polypropylene was performed in an effort to assess how the flow field that exists within a filament affects final as‐spun fiber morphology. It was concluded that the molten filament deforms chiefly by elongational flow, with some small amount of shearing flow bearing localized near the filament periphery. The resulting crystal texture is mostly comprised of lamellae oriented perpendicular (chain direction parallel) to the fiber axis, but a minority population of crystallites whose orientation is orthogonal (chain direction perpendicular) to the primary population is also present in these fibers. Post‐drawing steps initially cause crystallites to rotate toward the axial direction, while the chains within them undergo intralamellar slip and become better oriented parallel to the fiber axis. At larger extensions, lamellar crystallites are pulled into microfibrillar units.
Study of the variables affecting pressure drop and temperature rise in blow molding dies
Authors: Kim H. T. , Darby J. P. , Wilson G. F. 
Published: December 2004

AbstractThe extrusion head systems for both pipe and blow molding were analyzed theoretically and relationships derived between pressure drop and temperature rise for various materials at different flow rates and die restrictions.Because of the complexity of the geometry involved, the die was segmented into several sections axially and momentum and energy equations for these sections were solved with the help of IBM 360. The floating boundary conditions were used in order to take into account the nature of the flow phenomenon involved.To complement and support this theoretical work, rigid polyvinyl chloride (PVC) bottle compounds were used to obtain extrusion data on a 3½ inch extruder with several different die sizes. A good agreement was found between the predicted versus experimental data. Results showed that temperature rise in the die systems in significant and that neglecting it would result in a gross error in the calculated pressure drop.Based on this work, a simplified version of the theoretical equation was developed to serve as an engineering tool in estimating pressure drop and stock temperature for a given material where extreme accuracy is not essential. Results of the engineering equation which contains several empirical constants correlate well with the data and support the theoretical effort.
Solvent crazing of polystyrene and polymethylmethacrylate
Authors: Earl B. L. , Loneragan R. J. , Johns J. H. T. , Crook M. 
Published: December 2004

AbstractThe minimum surface strain required to induce crazing in polymethylmethacrylate and polystyrene in the presence of alcohols and n‐heptane has been determined at various temperatures by bending strips of the polymers around formers of varying curvature and immersing them in the liquid reagents. For each polymer/liquid system the long‐term crazing strain was independent of test temperature except within a single 30°C interval in which it decreased as the test temperature was raised. It was found that this temperature region corresponded to the glass‐rubber transition of the given polymer when, after extended periods of immersion it had achieved equilibrium liquid sorption. This suggested that, in the crazing tests, a condition approximating to equilibrium sorption was being established at the craze tip and that crazing occurred on applying small strains in the presence of the liquids because of their plasticising effect.It was found that not only the plasticizing effect of the liquid environment but also the liquid molecule size influenced the crazing strain; the larger‐molecule liquids caused lower long‐term crazing strains than did the smaller‐molecule liquids.
DTA for control of stability in polyolefin wire and cable compounds
Authors: Howard John B. 
Published: December 2004

AbstractDifferential thermal analysis offers a convenient and rapid way of determining stabilization levels in polyolefin compositions. Since it is normally used at temperatures in the fabrication range, it provides a direct readout of processing stability. At the same time, because the chemistry of the polymer system at these temperatures may be quite different from that at normal use temperatures, judgment must be exercised in attempting to extrapolate high temperature data. New factors can come in at either end of the temperature range which are inoperative at the other extreme.The experimental procedures used are described, and the special precautions necessary for operation down to the 140–150°C range indicated. Problems arising from sample inhomogeneities are discussed, and the critical importance of stabilizer migration in the solid state pointed out, including invalidation of extrapolation down to normal temperatures of data taken above the melting range.
Glass transition temperature as a guide to selection of polymers suitable for PTC materials
Authors: Meyer J. 
Published: December 2004

AbstractIt has been shown that the only way to predict the size of the PTC effect displayed by a crystalline polymer when filled with conductive particles is through the knowledge of the glass transition point of the polymer. The size of the PTC anomaly is found to decrease sharply with rise in glass transition temperature and for a polymer to be a useful PTC material its glass transition must be below 0°C. It has not been possible to explain this relationship by any of the current theories of the PTC mechanism in filled polymers.
The measurement of melt flow and melt stability
Authors: Longworth Ruskin 
Published: December 2004

AbstractThe melt flow of a plastic as measured by the standard method (ASTM D‐1238) is at a high enough stress so that the flow is non‐Newtonian. If the die in the plastometer is replaced by a nonstandard, tapered die of large orifice, a lower stress can be used and the flows are shown to be comparable to Newtonian viscosities measured in a cone and plate rheometer. Under these conditions the plastometer can be used as a sensitive measure of the melt stability of a plastic.
Stress‐strain behavior of polychloroprene vulcanizates containing polymer‐gel particles
Authors: Kawasaki Nobuhiro 
Published: December 2004

AbstractThe equations of stress‐strain of gel‐filled polymer under large deformation were derived by using a simple model i.e. a sphere in a cubic matrix. The author finds for no adhesion between the phases:equation imageIn case of perfect adhesion between the phases:equation imagewhere σ(α) is the stress of a blend at an elongation ratio of α, σR(α) the stress of a rubber matrix at α, σG(αG) the stress of a gel component at αG, σR(αR) the stress of a rubber matrix at αR, ϕ the volume fraction of gel. The validity ofEq 1was shown for the polychloroprene vulcanizates containing polystyrene‐gel which exhibits no adhesion with the polychloroprene matrix. This result shows the value of the model proposed here. The tensile strength of polychloroprene vulcanizates filled with polychloroprene‐gel at break is discussed by the use ofEqs 2–4.
Simulation of the mold‐filling process
Authors: Wu P.‐C. , Huang C. F. , Gogos C. G. 
Published: December 2004

AbstractThe transport equations for a power law fluid are used to solve the transient and non‐isothermal problem of filling a disk‐shaped cavity. Using the results obtained it is possible to predict gate pressures, fill times and short shots. Furthermore, the velocity and temperature fields can be obtained throughout the filling process. This information specifies the formation of a frozen surface layer during filling. Rigid PVC was primarily used in the simulations, but some results are also given for linear polyethylene, nylon 6–6, ABS and polystyrene.