bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and properties of cellulose graft copolymers. I. Radiation‐induced rayon–styrene graft copolymer
Authors: Huang Robert Y.‐M. 
Published: April 2003

AbstractRayon–styrene graft copolymers were prepared by the direct radiation method, with the use of the preswelling technique, by irradiation with γ‐rays from 60Co. The grafting was carried out in bulk styrene and in styrene–solvent mixtures, such as styrene–methanol and styrene–acetone, to study their effect on the graft copolymerization reaction and the structure of the resulting graft copolymer. The effects of carbon tetrachloride, a chain‐transfer agent, was also investigated. Three different types of rayon yarn were used; Fortisan, a modifier‐type high wet‐modulus rayon, and a high‐tenacity tire yarn, in order to study the effect of rayon microstructure on the grafting reaction. The molecular structure of the rayon–styrene graft copolymers was studied by hydrolyzing away the cellulose backbone and measuring the molecular weights of the grafted polystyrene branches. For grafting in bulk styrene, the molecular weights of the grafted polystyrene ranged from 400,000 to 1,000,000, while those of the polystyrene homopolymer formed in the outside solution were of the order of 30,000–50,000. The molecular weights of the grafted polystyrene branches tended to increase with per cent grafting in the graft copolymer. For grafting in styrene–methanol and styrene–acetone mixtures, the molecular weights of the polystyrene branches decreased with increasing solvent content. The addition of carbon tetrachloride to bulk styrene resulted in a sharp decrease in the molecular weights of the grafted branches. The grafting frequency or number of polystyrene branches per cellulose chain was calculated from the per cent grafting and the molecular weights of the polystyrene branches. The morphology of the rayon–styrene graft copolymers and some of their physical properties are discussed.
Fatigue of rubber at low strains
Authors: Lake G. J. , Lindley P. B. 
Published: April 2003

AbstractThe fatigue failure of natural rubber vulcanizates undergoing repeated low tensile deformations has been investigated. It is found that below a critical deformation the life is greatly influenced by the ozone concentration in the test atmosphere. This result was anticipated theoretically from previous studies of cut growth behavior, and the theory enables the combined effects of the two cut growth mechanisms—mechanicooxidative rupture and ozone scission—to be taken into account in predicting fatigue life.
Molecular weight distribution in a polymer film degraded by light
Authors: Shultz Allan R. 
Published: April 2003

AbstractAn explicit expression is derived for the weight distribution function of polymer molecules in a photodegraded film. A most probable weight distribution of linear molecules is assumed initially present; normally incident, monochromatic light obeying a single Beer‐Lambert absorption relation is the photolyzing radiation. The dependence of the weight distribution upon the film's optical thickness and the integrated incident light flux is illustrated by curves computed according to the derived functions. Predicted gel permeation chromatograms are indicated.
Role of capillary end correction in flow analysis of molten polyethylene
Authors: Ram A. , Narkis M. 
Published: April 2003

AbstractThe role of the capillary end correction in flow analysis of molten low‐density polyethylenes has been analyzed. In spite of limitations of accuracy a quantitative approach has been undertaken. The results are much more complicated than predicted by Bagley in his early reports. The elastic component of the end correction is controlled by shear stress and shear modulus. The latter is affected by the size of the subchain between entangles, Me, and by the degree of long‐chain branches. Both are eventually dependent on the length of the chain, i.e., its molecular weight. In addition shear stress and temperature affect the process of disentanglement. Capillary end correction increases with increasing molecular weight and shear stress and with decreasing temperature. The available analysis of branching is still in controversy, and therefore no numerical parameters are yet proposed. A consistent theory of the response of entanglement couplings to shear forces and temperature is evaluated.
Carboxyethylation of cotton by treatment with acrylamide
Authors: Reinhardt Robert M. , Bruno Joseph S. 
Published: April 2003

AbstractNew methods for the treatment of cotton with acrylamide have been studied which permit the preparation of modified fabrics with relatively high degrees of carboxyethyl substitution. Wet treatment with acrylamide and sodium hydroxide can be used to produce cottons bearing both carboxyethyl and carbamoylethyl ether substituents. Adjustment of reaction conditions controls the amount and ratio of these substituents. The effects of varying the concentrations of the reactants, the time and the temperature of reaction, and the solvent media employed have been determined. Some elucidation of the chemical mechanisms is provided. Previous work has shown that dry heat treatments of cotton impregnated with acrylamide and alkali can be used to produce high carbamoylethyl substitutions with little or no carboxyethyl substitution. The present work provides an extension of the cotton‐acrylamide treatment whereby fabrics can be produced with only carboxyethyl or carbamoylethyl groups, or with mixtures of the two.
Cast polyacrylonitrile. I. Casting methods
Authors: Pellon J. J. , Smyth N. M. , Kugel R. L. , Thomas W. M. 
Published: April 2003

AbstractClear sheets of polyacrylonitrile are prepared by casting under conditions whereby an adequate supply of monomer is available to the polymerizing mass and process variables are closely controlled. This surprising behavior can be extended to some copolymers of acrylonitrile and to certain other vinyl compounds that polymerize by precipitation of polymer.
Dependence of physical properties on composition in a series of high load‐bearing polyurethane foams. Part II. Effects of variations in reactant ratios
Authors: Mendelsohn Morris A. , Black Richard G. , Runk Robert H. , Minter Herbert F. 
Published: April 2003

AbstractData and interpretations are presented on the effects of chemical variations on the physical properties, and in particular, the compression–deflection characteristics of a series of high load‐bearing, open‐celled, shock‐mitigating polyurethane foams. The load‐bearing capability of the foam is considered to be a function of density and intrinsic stiffness of the polymer. Polyol components of the formulations consisted of a poly (oxypropylene triol) of approximately 4000 molecular weight and ethylene glycol. The blowing agents were water and trimerized linseed fatty acids. A solution of polymethylene polyphenylisocyanate and tolylene diisocyanate comprised the isocyanate mixture. Stannous octoate and N‐ethylmorpholine were th̀e dual catalysts. Load‐bearing capability of the foam was raised by increasing the concentrations of the isocyanates, poly (oxypropylene triol), stannous octoate, and by employing higher ratios of polymethylene polyphenylisocyanate to tolylene diisocyanate. Decrease in compressive strength resulted from increasing the quantity of blowing agents and N‐ethylmorpholine. Increasing the quantity of ethylene glycol gave load‐bearing properties which increased to a maximum and then decreased. Chemical variations are analyzed in terms of their effects on the properties of the polymeric networks. These include crosslink density, number and distribution of hydrogen bonds, chain orientation and mobility, and relative selectivity of the various reactions. Effects on the overall bulk properties of the foam are discussed in terms of the chemical composition.
Effect of γ‐radiation on the dynamic mechanical properties of styrene–butadiene rubbers
Authors: Traeger R. K. , Castonguay T. T. 
Published: April 2003

AbstractThree different styrene–butadiene, gum rubbers were exposed to γ‐radiation doses ranging from 0 to 200 Mrad. The crosslink densities, hardness, and the dynamic mechanical properties were evaluated. All specimens increased in hardness and crosslink density during radiation. This was reflected in an increased storage modulus, broadened loss tangent maximum, and increased relaxation spectrum. The dynamic data are presented in master curves which were developed by using the WLF equation.
Polyvinylcarbazole foams. I. Preparation
Authors: Ellinger L. P. 
Published: April 2003

AbstractThe polymerization of vinylcarbazole in aqueous dispersion by azobisisobutyronitrile can yield–depending on the protective colloid used–polyvinylcarbazole beads or granules. These require impregnation by a polymer solvent and preferably also by azobisisobutyronitrile before they can be molded to panels or simple shapes.
Polyvinylcarbazole foams. II. Properties
Authors: Ellinger L. P. 
Published: April 2003

AbstractThe uniformity, heat and solvent resistance, and thermal conductivity of foamed polyvinylcarbazole have been examined. Compressive and tensile properties, dielectric constant, and loss factor have been determined between ambient temperature and the softening range. Some features of the properties are attributed to the degree of orientation of the polymer molecules, which is thought to be the greater, the lower the density of the foam. The good high temperature stability is attributed to sterically impeded reversibility of the polymerization of vinylcarbazole.
Thermal degradation of polymers. II. Mass spectrometric thermal analysis of phenol‐formaldehyde polycondensates
Authors: Shulman G. P. , Lochte H. W. 
Published: April 2003

AbstractThe degradation of phenol–formaldehyde polycondensates has been investigated by mass spectrometric thermal analysis to 800°C. The thermal oxidative mechanism proposed by Conley and co‐workers has been confirmed. Direct analysis of products at frequent intervals of a temperature‐programmed heating cycle demonstrates the existence of postcuring, general degradation, and char‐forming stages. Activation energies for formation of each product and for degradation of the polymer have been determined. Phenolic homologs, products of thermal scission of methylene–phenyl bonds, show high activation energies; oxidation products have activation energies comparable to or slightly higher than that for oxidation of methylene bridges to carbonyl groups. The tarry high molecular weight products found on pyrolysis at atmospheric pressure are not formed in high vacuum because recombination reactions of phenols and formaldehyde are minimized. Otherwise, no major change in product composition, as compared to the high heating rate pyrolysis–gas chromatographic investigation of Jackson and Conley, was observed.
Observations on the coefficient of friction of polypropylene film
Authors: Schael George W. 
Published: April 2003

AbstractData are presented relating the time change of the coefficient of friction of cast polypropylene films to changes in film density and concentration of surface lubricant. It is shown that during aging the density of polypropylene increases, thus causing a decrease in the friction coefficient. It is also shown that although the lubricant added to the polymer will diffuse to the surface of copolymer films, no diffusion occurred in polypropylene films.
Ultraviolet stabilizing monomers and polymers. II. Synthesis and polymerization of acrylate and methacrylate derivatives of 2,4‐dihydroxybenzophenone
Authors: Fertig J. , Goldberg A. I. , Skoultchi M. 
Published: April 2003

AbstractIn the addition of stabilizing agents to plastic materials, problems such as incompatibility, migration, volatility, and/or solvent extraction of the additive frequently arise. With a view toward overcoming such problems in the use of ultraviolet absorbing stabilizers, acrylate and methacrylate derivatives containing the 2‐hydroxy‐4‐alkoxybenzophenone moiety have been synthesized. The ultraviolet absorbing monomers were synthesized by reaction of 2, 4‐dihydroxybenzophenone with glycidyl acrylate and glycidyl methacrylate. They were homopolymerized and blended with poly(vinyl chloride), poly(vinylidene chloride), polystyrene, and poly(methyl methacrylate). They were also copolymerized with the corresponding monomers. The polymer blends and copolymers were investigated for ultraviolet stability versus corresponding controls. Effective ultraviolet stabilization was observed. Differences in the stability of some blends as compared to corresponding copolymers is thought to be due to incompatibility.
Dynamic mechanical properties of titanium dioxide‐filled poly(vinyl acetate) at 0–40°C.
Authors: Galperin I. , Kwei T. K. 
Published: April 2003

AbstractThe dynamic mechanical properties of titanium dioxide‐filled poly(vinyl acetate) have been studied at filler concentrations of 0, 10, 20, 30, and 40 wt.‐% TiO2 by using a torsional pendulum. The damping factor was found to increase with higher temperatures. At 40°C., the damping factors for the different TiO2 concentrations were estimated to be the same. Damping factors above 40°C. were difficult to obtain due to the rubbery nature of the TiO2–poly(vinyl acetate) systems. From 24 to 35°C., 10 wt.‐% TiO2‐poly(vinyl acetate) was closer in damping factor increase to unfilled poly(vinyl acetate) than to the higher TiO2‐content polymers. At all temperatures, damping factors decreased with higher TiO2 concentration. As the temperature decreased to 0°C., damping factors for the filled systems approached a common value. Potential energy of filled systems as indicated by shear modulus values is increased by higher TiO2 concentrations and lower temperature. Kinetic energy for the filled systems, as shown by the out‐of‐phase modulus, is actually increased by larger filler concentration and higher temperature. A model is proposed where introduction of TiO2 filler acts to increase general long‐range polymer chain stiffening and at the same time enables short‐range chain mobility to rise, possibly through greater side‐chain motion.
Studies with thin membranes. I. Characterization of parlodion membranes formed by multiple dip technique and by incorporation of lipoidal substances
Authors: Lakshminarayanaiah N. 
Published: April 2003

AbstractParlodion membranes formed by the dipping technique using solutions of Parlodion in isoamyl acetate of concentrations extending to 3% have been characterized. The thickness of the membrane increased with increase in the viscosity of the membrane‐forming solution. Although the membrane resistance increased with increase in its thickness, the specific resistance ρ of the different membranes was not a constant but increased with increase in thickness and showed a tendency to attain a limiting value. The effects of different cations at the same concentration and of the same cation at different concentrations on membrane properties have been studied. Membranes formed by multiple dips into the same solution and into different solutions of Parlodion have also been characterized in respect of their electrical resistance, capacitance, and specific resistance. In general, all Parlodion solutions on a second dip gave membranes of increased thickness and resistance. Subsequent dips always increased membrane thickness and resistance except in the case of 0.25% solution which produced a membrane of approximately the same thickness and resistivity. The dipping and the spreading techniques of membrane formation have been used to introduce stearic acid, phosphatidyl L‐serine, and cholesterol into the Parlodion matrix, and the lipoidal membranes so prepared have been characterized.
Some physicochemical properties of poly (ethyl acrylate) emulsions containing carboxyl groups
Authors: Muroi Soichi 
Published: April 2003

AbstractConductometric and potentiometric titration behavior of emulsions of ethyl acrylate copolymers with acrylic acid and methacrylic acid was investigated. On the conductometric titration curves of the emulsions of the copolymers with more than 5 mole‐% of the acids, two equivalence points, based on the copolymerized acids, were observed, but only one equivalence point was observed on potentiometric titration. Almost all of the copolymerized acids could be detected by both titration methods. The change in optical density of the dilute emulsions with their pH was measured. The particles of these emulsions were studied under an electron microscope. These results showed that, when the pH of the emulsions was raised, the surface layers of the particles began to dissolve and their cores started to swell near the pH of their first equivalence points. When the pH was again lowered the dissolved polymers coagulated, tiny particles were formed, and the swollen cores were dehydrated. The surface layers thickened with increasing amount of the copolymerized acid. These behaviors were very similar in the emulsions of the copolymers with acrylic acid and methacrylic acid. The quantity of water‐soluble polymers formed in the course of the emulsion copolymerization was approximately 3–4% or slightly more. This quantity depended only slightly upon the amount and type of the copolymerized acid. The acid contents of the water‐soluble polymers were higher in cases of the copolymers with acrylic acid than in those with methacrylic acid. No relationship with the amount of copolymerized acid was established.
Experimental determination of ultrasonic wave velocities in plastics as functions of temperature. I. Common plastics and selected nose‐cone materials
Authors: Arnold Ned D. , Guenther Arthur H. 
Published: April 2003

AbstractAn experimental study was conducted to determine previously unavailable data showing the relationship between temperature and the velocity of longitudinal ultrasonic waves through several plastics. The ultrasonic frequencies used were between 1 and 10 Mc./sec., and the temperature range covered was between room temperature and 100°C. Velocity–temperature curves were determined for nylon, a high‐ and a low‐density polyethylene, Plexiglas, Teflon, and for several reentry vehicle nose‐cone materials, including chopped nylon phenolic, tape‐wound nylon phenolic, Castable 124, Avcoat I, and Avcoat 19. Less complete data were obtained for Avco phenolic fiber glass, General Electric phenolic fiber glass, and oblique tape‐wound refrasil. These layered materials are difficult to measure, and the velocity of acoustic waves is very dependent on the direction of propagation with respect to the laminations. For most of the materials studied the velocity was found to decrease more or less linearly with increasing temperature. Typically, the velocities at 100°C. were 9–31% less than at room temperature.
Experimental determination of ultrasonic wave velocities in plastics as functions of temperature. II. Effect of lamination angle for layered materials
Authors: Dorr Anton J. , Guenther Arthur H. 
Published: April 2003

AbstractUltrasonic longitudinal wave velocities in layered materials were measured as a function of the lamination angle at several temperatures. It was found that the longitudinal wave velocity versus lamination angle curve maintains the same shape (for a given material) for temperatures between 25 and 125°C. Furthermore, it was found that the wave velocity versus lamination angle curve can be predicted to within 2% by a theoretical equation involving only the lamination angle, & thetas; (taken as the angle between the grain of the sample and the direction of sound propagation); c (0°), the measured wave velocity at an angle of 0°; and c (90°) the measured wave velocity at an angle of 90°. Finally, it was found that the longitudinal wave velocity of certain materials varies as much as 25% between lamination angles of 0° and 90°, while other materials show less variation, and some none at all.
Tensile strengths of glassy plastics with drilled holes and measurement of griffith parameters
Authors: Arends C. B. 
Published: April 2003

AbstractThe tensile strengths of plastics with drilled holes can be analyzed by treating the hole as a nucleus in flaw generation. The analysis is accurate for hole diameters less than the inherent flaw size. Above this value the tensile strengths define a single curve when plotted on a reduced variable scale. Using the analysis in its linear range facilitates evaluation of the Griffith parameters. From such an application it was found that plasticizers markedly reduce the values of the Griffith parameters while affecting tensile strengths only slightly. Temperature has a similar effect.
Effect of molecular structure on the thermal aging properties of flexible urethane foams
Authors: Smith C. H. , Degisi S. L. 
Published: April 2003

AbstractA series of flexible urethane foams was formulated from diisocyanate‐terminated polyether prepolymers, using both a polyether diol and an ethylenediamine tetraglycol as extenders. The long‐term compression set characteristics and the compression deflection properties of these foams were studied. The swelling effect in a solvent, the free isocyanate content, and the role of a carbon black filler on the flexible urethane foam formulation were also evaluated. It was concluded that the total amount of diisocyanate used in the formulation, rather than a variation in the type of isocyanate, has the greatest influence on molecular structure.
Kinetic study of the hydrolysis of cellulose acetate in the pH range of 2–10
Authors: Vos Kenneth D. , Burris Floyd O. , Riley Robert L. 
Published: April 2003

AbstractA kinetic study of the hydrolysis of 39.8 wt.‐% acetyl cellulose acetate has been made as a function of pH and temperature over the pH range of 2.2–10 and temperature range of 23–95°C. The hydrolysis reaction was carried out on highly porous membranes under quasihomogeneous conditions and the data have been treated as a pseudo‐first‐order reaction in acetyl concentration. The reaction can be represented by the equation \documentclass{article}\pagestyle{empty}\begin{document}$k_1 {\rm = }\;k_{\rm H ^ +} \left[ {{\rm H^+}} \right]{\rm +}k_{\rm OH^-}\left[ {{\rm OH}^ - } \right] + k_{\rm H_2O} $\end{document}, and where \documentclass{article}\pagestyle{empty}\begin{document}$k_{\rm H} ^ + {\rm = 5}{\rm .24}\;{\rm x 10}^{\rm 5} {\rm exp }\left\{ {{\rm &#x02010; 16}{\rm .4 x 10}^{\rm 3} /RT} \right\},{\rm }k_{{\rm OH}} ^ &#x02010; {\rm = 1}{\rm .55}\;{\rm x 10}^{\rm 4} {\rm exp }\left\{ {{\rm &#x02010; 8}{\rm .1 x 10}^{\rm 3} /RT} \right\}$\end{document}, and \documentclass{article}\pagestyle{empty}\begin{document}$k_{\rm H_2O} {= 4.25\;\times 10}^{- 2} {\rm exp }\left\{ {{- 11.5 \times 10^3 /RT}} \right\}$\end{document} (where the quantities in brackets are activities of the ions shown).
Monolayer film behavior of polymers and their mixtures
Authors: Labbauf Abbas 
Published: April 2003

AbstractThe monomolecular film behavior of polyvinyl acetate (PVAc), polyethyl acrylate (PEA) and mixtures of these ranging in concentration ratio of PEA to PVAc from 0.008 to 11.301 has been studied using a Langmuir‐type filmbalance over an aqueous 0.01N HCl substrate. Hysteresis was observed in the compression–expansion cycle for PVAc. A discussion of polymer–polymer interaction in a mixed monomolecular film at an interface is presented. The extent of this interaction for films comprising PVAc and PEA has been determined in terms of deviations of the film area from the ideal behavior. The data on the film areas of PVAc and PEA are discussed in terms of the molecular orientation of these polymers on the surface. A simple equilibrium thermodynamic treatment is applied to the data on mixed monolayer films. The implications resulting from this study are discussed.