bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of peracid‐type resins and their characteristics as oxygen transfer agents
Authors: Takagi Toru 
Published: April 2003

AbstractSynthesis of peracid‐type resins (PAR) by oxidation of carboxylic acid‐type ion exchangers with H2O2 in sulfonic and sulfuric acid media has been studied. Influence of composition of the resins and acid concentration of the media on the conversion of carboxylic to percarboxylic acid groups in the resins is discussed. PAR can oxidize various organic compounds in good conversion. It is especially noteworthy that the increase in the polarity of the solvent increased the rate constants in the epoxidation of cyclohexene with PAR, in contrast with the low molecular weight peracids, and the epoxidation of 1‐olefins, geometric isomers of cyclododecene, and cholesterol with PAR took place selectively with regard to chain length or steric configuration. The results are discussed on the basis of distribution effect, protective effect with polymer, steric interactions between overall molecule of the substrates and polymer matrix, and other factors.
Solvent effect on the time constant of concentrated polymer solutions
Authors: Rao Vadlamudi G. , Gandhi K. S. 
Published: April 2003

AbstractThe time constant, τ, signifying the onset of non‐Newtonian behavior of polymer solutions is known to be a function of mass concentration, C, molecular weight, M, temperature, T, and zero shear viscosity, η0. Williams' theory predicts that the time constant is also affected by the solvent character. To study the predicted effect, the time constants of poly(methyl methacrylate) solutions in chlorobenzene (good solvent) and m‐xylene (poor solvent) were experimentally determined. It was found that the ratio of the time constant to the Rouse relaxation time was a function of the combined variable CM. For all values of CM, both the time constant and the ratio of the time constant to the Rouse relaxation time were larger in a poor solvent than in a good solvent. This behavior may be attributed to the relatively stronger attractive interpolymer molecular forces present in solutions in poor solvents. As the temperature is raised the poor solvent becomes better and the ratio of the time constant to the Rouse relaxation time is found to become independent of solvent character.
Preparation of reverse osmosis membranes by surface modification of polymeric films. I. Surface acetylation of cellulose
Authors: Hillman J. J. 
Published: April 2003

AbstractSurface acetylation of cellophane to afford an asymmetric membrane having high desalination ability (as high as 98% sodium chloride rejection) is described. The films were characterized by multiple‐internal‐reflectance microscopy (MIR), dyeing tests, light microscopy, and determination of water and sodium chloride transport properties in reverse osmosis cells. Surface modification employing acetyl chloride and acetic anhydride was studied in detail: the influence of the cellophane employed, the degree of cellophane activation, reaction time, reagent concentration, and diluent were assessed. Mixed acetylation reactions are also discussed as well as an evaluation of various postconditioning treatments used to increase desalination.
An apparatus for the measurement of dynamic mechanical properties of polymers in a gas medium with the vibron viscoelastometer
Authors: Murayama Takayuki , Silverman Bernard 
Published: April 2003

AbstractThe Vibron Viscoelastometer is useful for obtaining dynamic mechanical properties of film and fibers in atmospheres at 0 and 100% relative humidity. No apparatus has previously been available for obtaining dynamic mechanical properties in a gas medium; however an apparatus and procedure have been developed for measuring these dynamic properties in a gas medium using the Vibron instrument. This technique will be useful in studies on the effects of different gases on polymers in the process and on the effects of gas treatments on materials. A new gas cell which is adaptable for other mechanical testing instruments such as the Instron, Tensometer, and Torsion Pendulum is also discussed.
Polypropylene fibers melt‐spun in the presence of torsional shear
Authors: Andersen P. G. , Test S. , Deo S. R. , Carr S. H. 
Published: April 2003

AbstractMelt‐spun fibers of isotactic polypropylene have been formed using specific combinations of shearing and elongational flow. Such rheological conditions were achieved with a take‐up device capable of subjecting molten polymer filaments continuously to various combinations of torsional and elongational strains. Relationships were determined between mechanical properties of the resulting fibers and their molecular organizations. The results obtained indicated that these flow fields would produce fibers whose mean‐preferred‐chain‐orientation directions ranged between being tilted radially from a direction parallel with the fiber axis (no torsional shear strain imposed) and having some additional tilt that is tangential with respect to the fiber circumference (some torsional shear strain imposed). It is not possible to resolve the observed helical chain tilts into contributions from crystalline and amorphous regions, respectively.
The rheological properties of molten mixtures of polyoxymethylene and copolyamide: Their fibrillation and microstructure
Authors: Ablazova T. I. , Tsebrenko M. B. , Yudin A. B. V. , Vinogradov G. V. , Yarlykov B. V. 
Published: April 2003

AbstractThe rheological properties of molten mixtures of polyoxymethylene and copolyamide have been investigated by the methods of capillary viscometry over a wide range of shear stresses. It has been found that at relatively close values of the melt viscosity polyoxymethylene (POM) and copolyamide (CPA) form mixtures which differ markedly in viscosity and elastic properties from the original polymers. Depending on the magnitude of the shear stress, the viscosity of mixtures of definite composition may be either higher or lower than the viscosity of the components. Three‐ to tenfold swelling of the stream emerging from the capillary is observed for such mixtures, whereas at the same temperatures and stresses no swelling of the POM and CPA extrudates is practically observed. The data obtained are accounted for by the fact that the flow of mixtures through the capillary involves the formation of hundreds of thousands of ultrathin fibres of POM in the matrix of CPA, which are oriented along the flow axis.
Determination of heats of volatilization for polymers by differential scanning calorimetry
Authors: Frederick W. J. , Mentzer C. C. 
Published: April 2003

AbstractIn the design of thermal degradation processes for polymers, the energy to degrade or volatilize the materials soften must be known. The heats of volatilization for six polymers were measured by differential scanning calorimetry (DSC), where the area under the degradation endotherm peak was shown to be directly proportional to the heat of volatilization. Values measured for poly(methyl methacrylate), which yields monomer quantitatively in the temperature range investigated, agree well with theoretically predicted values. Reproducibility of the method is shown by an average standard deviation of ±10% for the six polymers investigated. Caution must be used when applying data obtained by this method to thermal conditions widely differing from those employed in the DSC.
Thickness variation in the thermoforming of poly(methyl methacrylate) and high‐impact polystyrene sheets
Authors: Lai M. O. , Holt D. L. 
Published: April 2003

AbstractThe influence of material flow properties on the variation of wall thickness in a thermoformed part was investigated by measuring the thickness reduction at the pole of free‐formed axisymmetric domes of poly(methyl methacrylate) and high‐impact polystyrene. It was found that at a given pole height, the thickness reduction in poly(methyl methacrylate) was less than in high‐impact polystyrene, i.e., the wall thickness in a part formed from poly(methyl methacrylate) will be more uniform than in a part formed from high‐impact polystyrene by the same technique. This difference in formability was ascribed to a difference in the dependence of the flow stress σ at the thermoforming temperatures on time. The flow stress of both materials was given by σ = Ktm′ϵn, but whereas n was approximately 1 for both materials, m′ was −0.052 and −0.33 for poly(methyl methacrylate) and high‐impact polystyrene, respectively. A physical argument and simple analysis led to the conclusion that a large (negative) value of the “stress relaxation index” in a material reduces the degree of uniformity of sheet thickness in a formed part.
Polyurethane–polyacrylate interpenetrating polymer networks. II
Authors: Frisch K. C. , Klempner D. , Migdal S. , Frisch H. L. , Dunlop A. P. 
Published: April 2003

AbstractTwo component topologically interpenetrating polymer networks of the SIN type (simultaneous interpenetrating networks) composed of a melamine‐cured polyacrylate and three different polyether‐based polyurethanes were prepared. The linear polymers and prepolymers were combined in solution, together with the necessary crosslinking agents and catalysts, films were cast and subsequently chain extended and crosslinked in situ. In all cases, maxima in tensile strength significantly higher than the tensile strengths of the component networks occurred at 50% polyurethane : 50% polyacrylate. This was explained by an increase in crosslink density resulting from interpenetration. One of the interpenetrating polymer networks showed only one glass transition temperature (Tg) (measured calorimetrically) intermediate in temperature to the Tg's of the components and as sharp as the component Tg's. This is indicative of phase mixing and indicates at least partial chain entanglement (interpenetration). Some enhancement of other physical properties was also noted.
Effect of polymeric silane coupling agents on adhesion of polypropylene and polystyrene to glass
Authors: Inoue Hiroshi , Kohama Shigemi 
Published: April 2003

AbstractThe coupling performance of some polymeric silane compounds was compared with that of the monomeric silanes for adhesion of polypropylene (PP) and polystyrene (PS) to glass. A silylated poly‐1,2‐butadiene was found to be effective for PP and, on the other hand, some copolymers derived from styrenyl triethoxysilane or γ‐methacryloxypropyl trimethoxysilane for PS. Benzoyl peroxide also showed a pronounced effect on the adhesion of PP, rather than that of PS. The adhesion strength was approximately correlated with the contact angles of the resin melts on the coated glass, intensively suggesting the dependence of compatibility between resinous matrix and coupling agent on the adhesion. Their critical surface tensions, thermal behavior, and infrared spectra were also measured to discuss the relationship between the surface constitution and the adhesion effect.
The limits of linear viscoelasticity in poly(methyl methacrylate) and poly(ethyl methacrylate)
Authors: Bertilsson Hans , Jansson Jan‐Fredrik 
Published: April 2003

AbstractThe limit of linear viscoelasticity is determined for poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) in uniaxial tension creep over the temperature range of 20° to Tg −10°C. The time span covered is from 10 to 1000 sec. The linear limit is defined as the point at which the creep compliance deviates by more than 1% from its mean value in the linear viscoelastic range. For both materials, the stress limit of linear viscoelasticity falls to a minimum or plateau level at a temperature below Tg. It is suggested that the β‐mechanism plays an important role in the existence of this minimum.
Anionic graft copolymers. I. Poly(vinyl chloride)‐g‐polystyrene. Preparation and characterization
Authors: Lechermeier G. , Pillot C. , Gole J. , Revillon A. 
Published: April 2003

AbstractGraft copolymers of PVC‐g‐PS of controlled branching were prepared by carbanionic deactivation. The reaction products were characterized mainly by GPC. It appears that secondary reactions affect the efficiency of the grafting, chiefly at low ratios of polystyrene to poly(vinyl chloride). Techniques of grafting and analyses are discussed.
Determination of formation and relaxation of crazes by permeability measurements
Authors: Nicolais L. , Drioli E. , Migliaresi C. 
Published: April 2003

AbstractFormation and relaxation of crazes on different polymeric films are determined by permeability measurements in a high pressure test cell. Thermal dependence of the films permeability has been studied and interpreted on the basis of segmental movement of the macromolecules.These permeability measurements also offer a way to determine the glass transition temperature of amorphous films.
Strain energy functions of rubber. I. Characterization of gum vulcanizates
Authors: James A. G. , Green A. , Simpson G. M. 
Published: April 2003

AbstractA plot of principal stress difference versus principal extension ratios has been used as a graphic representation of general deformation. Two analytic forms of the strain energy function for isotropic, incompressible materials are suggested. These involve five or nine terms, the coefficients of which are found by regression to the general deformation plot. The resulting stress–strain equations are used to predict particular deformations, for example, simple extension, and are also evaluated in model engineering desing experiments. These experiments use interative techniques to predict the shapes and pressures of inflated diaphragms and tubes, and it is shown that the equations lead to accurate results even at relatively high extensions.
Retention of thermal antioxidants in polyethylene by silane coupling agents. III. Copper deactivators
Authors: Albarino R. V. , Schonhorn H. 
Published: April 2003

AbstractStabilizer activity has been correlated with physical retention and state of dispersion in aged polyethylene films. Incompatibility and poor state of dispersion were found to limit long‐term performance of otherwise chemically efficient stabilizers. A practical method to improve compatibility and state of dispersion of stabilizers involves complexation of nonfunctional stabilizer phenolic groups with N‐β‐(aminoethyl)‐γ‐aminopropyltrimethoxysilane. Substantial improvement in retention and state of dispersion may be realized with antioxidant–silane weight ratios of 1:1.
Effect of nucleating agents upon the kinetics of poly(ethylene terephthalate) crystallization
Authors: Przygocki Wladyslaw , Wlochowicz Andrzej 
Published: April 2003

AbstractExperiments have been conducted to examine the effect of the following agents: TiO2, CaO, MgO, BaSO4, SiO2, and Al2O3 as modifiers on the poly(ethylene terephthalate) crystallization kinetics. Modifier concentration in the polymer varied from 0.5% to 3%. Crystallization rate measurements at a temperature of 237°C were performed by dilatometric method and measurements of spherulitic growth rate, by microscopic method. It has been stated that the addition of a modifier affects the crystallization rate, dimension, and homogeneity of spherulitic sizes. The spherulitic growth rate, with the exception of that modified by CaO, does not depend on the kind and the concentration of a modifier. Heterogeneous nucleating agents exert an effect, then, mainly on the heterogeneous nucleation process. In the presence of the agents, the nucleation in the poly(ethylene terephthalate) is of athermal character. The kind of a modifier applied exerts also an effect on the final crystallization degree.
Fluorocarbon bibenzoxazole polymers: Transitions and thermal stability
Authors: Schoff C. K. , Gillham J. K. 
Published: April 2003

AbstractThe thermomechanical behavior (−180° to 500°C) in nitrogen is reported for two fluorocarbon bibenzoxazole homopolymers and a corresponding copolymer. The dynamic mechanical spectra were generated at low frequencies (∼1 Hz) by an adaptation of the torsional pendulum, torsional braid analysis (TBA), which uses polymer/glass braid composites as specimens. The effects of the variations in molecular structure on physical transitions and thermal stability are discussed. Of particular interest are the specific submolecular assignments for the two glassy‐state transitions (T < Tg) found for each polymer.
The states of water in cellulose acetate membranes
Authors: Taniguchi Yoshio , Horigome Shinkichi 
Published: April 2003

AbstractDifferential scanning calorimetric melting endotherms of wet and half‐dried cellulose acetate membranes and salt distribution coefficients were studied to clarify the states of water in membranes. We have suggested that (a) there are four states of water in cellulose acetate membranes; (b) these states of water are those of completely free water, free water very weakly interacting with polymer, bound water which can contain salts, and bound water which rejects salts; (c) the semipermeability of membranes depends on the ratio of four states of water in membranes.
The effect of UV light on the subsequent thermal volatilization of poly(methyl acrylate)
Authors: McGill W. J. 
Published: April 2003

AbstractFilms of poly(methyl acrylate) were exposed to UV light for periods of up to 45 min and were then degraded thermally under vacuum and at atmospheric pressure in nitrogen. Short exposures caused a marked decrease in the initial rate of thermolysis, and this was attributed to the removal of active centers. The formation of crosslinks during photolysis severely decreased the subsequent rate of volatilization of the polymer by inhibiting the unbuttoning chain reaction mechanism. Volatilization of exposed films under vacuum was slower than at atmospheric pressure in nitrogen, and this was attributed to the loss by evaporation of active centers. Activation energies for thermolysis before and after UV exposure were 160 and 167 kJ/mole, respectively. The subsequent thermal behavior of films exposed to UV light in oxygen and nitrogen atmospheres was closely similar.
Reversible amine solubilization of cured siloxane polymers
Authors: Hsiao Y.‐C. , Hill L. W. , Pappas S. P. 
Published: April 2003

AbstractWe report that aliphatic primary and secondary amines completely solubilize crosslinked silicone resins and rubber compositions at room temperature. The solubilization is attributed to nucleophilic cleavage of SiO bonds by amines, which apparently occurs selectively at crosslinking sites. The selectivity may reflect the presence of three oxygen atoms at such sites, which are expected to enhance the electrophilicity of silicon. On evaporation of amine, crosslinks are apparently regenerated as evidenced by solubility characteristics as well as film properties of the reclaimed silicones. In addition to their theoretical interest, these results are potentially important from the standpoint of commercial applications as well, including the possible reclaiming of silicone‐constituted furniture molds and the coating of heat‐sensitive materials.
Energy balances and uniaxial damage of highly filled elastomers
Authors: Lepie Albert H. , Adicoff Arnold 
Published: April 2003

AbstractA propellant sample undergoes internal damage while it is tested at finite deformation. The damage consists of broken molecular chains and void spaces which form around the filler particles and contribute to failure of the propellant. Attempts were made to determine the amount of this damage from the viewpoint of energy dissipations. Mechanical energy losses, called damage energy, were computed from energy changes during tension cycling experiments carried out at different temperatures and straining rates. Shift procedures were applied to the experimental results, and a double‐reduced master curve for damage energies was obtained by using time–temperature and strain shift factors. The reduced master curve can be used to predict the extent of damage accumulated in a propellant sample during tensile tests at different straining rates and temperatures.
Thermal analysis of poly(1,3,4‐oxadiazole‐2,5 diyl‐1,2‐ethenediyl) and poly(1,4‐phenylene‐1,3,4‐oxadiazole‐2,5 diyl‐1,2 ethendiyl)
Authors: Varma I. K. , Geetha C. K. 
Published: April 2003

AbstractPoly(1,3,4‐oxadiazole‐2,5‐diyl‐1,2‐ethendiyl) and poly(1,4‐phenylene‐1,3,4‐oxadiazole‐2,5 diyl‐1,2‐ethenediyl) have been prepared by condensation polymerization using fuming sulfuric acid and different quantities of terephthalic acid (T), fumaric acid (F), and hydrazine sulfate (HS). Homopolymers of F and T and various copolymers of F:T have been prepared. The polymer structure was investigated by IR and visible‐range spectra and elemental analysis. The existence of poly(1,3,4‐oxadiazole‐diylphenylene) and poly(hydrazoterephthaloyl) structures was revealed by these studies. These polymers were thermally stable, and most of them did not show a weight loss below 350°C. The relative thermal stabilities of the various polymers have been evaluated by “integral procedural decomposition temperature” and activation energy measurements.
Morphological studies on wettability and tackiness of pressure‐sensitive adhesives
Authors: Hino Kinnosuke , Ito Toshio , Toyama Mitsuo , Hashimoto Hatsujiro 
Published: April 2003

AbstractThe surface structure of pressure‐sensitive adhesives consisting of natural rubber and pentaerythritol ester of hydrogenated rosin has been studied using the single‐stage replica method. The fibril structure with average diameter of about 50 Å was observed on the surface of an adhesive consisting of 40 to 60 wt‐% resin at which maximum tack is obtained. The role of fibrils in adhesion is discussed.
Criterion of ion separation by reverse osmosis
Authors: Fang Herbert H. P. , Chian Edward S. K. 
Published: April 2003

AbstractThe order of ion separation by the NS‐100 membrane differed slightly from that of the cellulose acetate membrane. The separation of an ion by the NS‐100 membrane increased with increase in the valence of the ion, but decreased with the increase in the ionic radius. The sole criterion determining this separation order for the NS‐100 membrane was the enthalpy of hydration. An ion having a higher enthalpy of hydration is bulkier in the hydrated form and is, therefore, separated more effectively by the NS‐100 membrane, according to the diffusional model of solute separation. The permeability of an ion through the membrane material can be related to its enthalpy of hydration. By using this relationship, the separation of individual ions in aqueous solution with a given NS‐100 membrane can be predicted from a test with a sodium chloride solution.
New method of determining contact angle between monofilament and liquid
Authors: Yamaki Jun‐Ichi , Katayama Yuzo 
Published: April 2003

AbstractThis paper describes a method to obtain contact angle by observing the shape of a liquid drop attached to a monofilament. The relations between contact angle and the dimensions of drops are theoretically obtained. Thus, it is possible to calculate the contact angle if drop shape is measured. Through use of this method, the contact angles of epoxy resin on various kinds of monofilaments were measured. It was found that this method has practical utility for measurement of the contact angle between liquid and monofilament.