bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic mechanical measurements on monofilaments
Authors: Rong Shu‐De , Williams H. Leverne 
Published: April 2003

AbstractMonofilaments were obtained or extruded and drawn to representative degrees. The dynamic mechanical properties of polyether based polyurethane, high density polyethylene, and polycaprolactam monofilaments produced commercially and of laboratory prepared monofilaments of low and high density polyethylene, poly(ethylene terephthalate), and poly(tetramethylene terephthalate) were measured. The data are compared with those from oriented film and amorphous or unoriented film when possible. The effect of orientation on the properties was clearly detectable as was the effect of absorption of water vapor on polycaprolactam.
Effect of a variation in kinetic parameters (rate constant, activation energy) on the vulcanization of rubber sheets in injection molding process
Authors: Ferradou C. , Rochette B. , Vergnaud J. M. 
Published: April 2003

AbstractAs shown previously, a slight variation in the kinetic parameters (rate constant, activation energy) of the cure reaction has a pronounced effect on the vulcanization of rubber. The purpose of this work is to show that this effect is more important when the injection molding process is used and the temperature of injected rubber is higher. Experiments were performed using microcalorimetry for determining the kinetic parameters, and a heated mold pressing a 2 cm thick rubber sheet. The resulting variations in the temperature and state of cure at the midplane of sheets were calculated and compared for different temperatures of injected rubber ranging from 40 to 140°C, while the temperature of the mold was kept constant at 180°C.
Antiinflammatory polymer‐bound steroids for topical applications. I. Synthesis and characterization
Authors: Khue Nguyen Vu , Galin J. C. 
Published: April 2003

AbstractCovalent binding of hydrocortisone and dexamethasone to hydrophylic biocompatible macromolecular carriers through hydrolizable carbonate linkage was investigated according to two complementary strategies. (a) Radical copolymerization of hydrocortisone‐21C‐vinylcarbonate with N‐vinylpyrrolidone (NVP,60°C), or N‐[tris(hydroxymethyl)methyl]acrylamide (THMMA, 50°C) in dimethylacetamide solution: In spite of a nearly zero reactivity ratio for the steroid monomer which behaves as a degradative transfer agent—CT ∼ 5.7 × 10−2 and 6.8 × 10−3 for NVP and THMMA, respectively–this process may afford fairly high molecular weight polymers (M̄w ≃ 104–105) with high enough hydrocortisone content (0.03–0.10 mole.fraction). (b) Condensation of the hydrocortisone or dexamethasone‐21C‐chloroformates onto poly(oxyethylene glycol) (M̄n = 6220) or hydroxypropylcellulose (HPC, M̄w = 1.35 × 105) in tetrahydrofuran solution (30°C): This straightforward process is of low efficiency (yields >50%), and only HPC derivatives show good chemical homogeneity.
Estimation of interaction between polyanions and bovine serum albumin by means of affinity chromatography
Authors: Kuramoto Noriyuki , Sakamoto Munenori , Komiyama Jiro , Iijima Toshiro 
Published: April 2003

AbstractThe ligand binding of some polyanions to bovine serum albumin immobilized on Sepharose 4B has been studied by column affinity chromatography. Frontal chromatography using a polyanion of low concentration on an affinity adsorbent gave the dissociation constant Kd of the polyanion‐immobilized ligand complex. Kd values determined under various concentrations enabled us to discuss in detail the interactions of bovine serum albumin and polyanions.
Dielectric and dynamic mechanical behavior of poly(vinyl acetate) containing small concentrations of cholesteryl additives
Authors: Deshpande D. D. , Kandaswamy N. R. , Tiwari V. K. 
Published: April 2003

AbstractDielectric loss measurements at four temperatures and as a function of frequency are presented for the poly(vinyl acetate) (PVAc) systems containing small concentrations of cholesterol, cholesteryl acetate, cholesteryl oleate, cholesteryl nonanoate, cholesteryl benzoate, cholesteryl oleyl carbonate, p‐methoxy benzilidine‐p‐n‐butyl aniline, diphenyl ether, and cetyl acetate. For the first five systems, the α‐relaxation temperature for sure PVAc was found to be increased in the presence of the said additives. The results of the dielectric depolarization spectroscopy at 1 kHz and the dynamic mechanical analysis also conform with these observations. It is inferred that the segmental motion in PVAc is hindered by these first five additive molecules through a specific dipolar interaction. These additives are therefore described as antiplasticizers to PVAc as they extend the glassy region over a wider temperature interval. The analysis of the dielectric data to give the dielectric decay function and the β parameter reveals that the two types of the additives, viz., plasticizers and antiplasticizers, can be distinguished by the opposite signs obtained for the ratio Δβ/ΔC, where C is the concentration. The analysis based on the WLF theory shows that the WLF reference temperature T0 is higher than that for pure polymer if the additive is an antiplasticizer while the same is lower for the plasticizing additives. The apparent enthalpy of activation for the dielectric relaxation process is found to be higher in the case of additives which show antiplasticization of PVAc.
A new hydrostatic compression tester for anisotropic filled polymers
Authors: Lepie Albert H. , Moran Mark B. 
Published: April 2003

AbstractThis paper describes a testing device designed for measuring the isotropic or anisotropic hydrostatic compression properties of filled polymers like solid propellants, including the initial void content and the bulk modulus. The propellant test samples used are either cubical, cylindrical, or rectangular specimens. Three pressure‐sealed linear variable differential transformers (LVDTs) are used to monitor the dimensional changes of a cube specimen during hydrostatic pressurization simultaneously in the XYZ directions. The moduli E11, E22, and E33 and the compression strain ratios v21, v32, and v31 can be determined as a function of pressure. The three LVDTs can also be used to measure the length changes of three rectangular or cylindrical test specimens under hydrostatic compression only in the vertical Z direction. The bulk modulus and void content can be computed when isotropic behavior is assumed. The entire test procedure is controlled by an Apple II microcomputer via an AI13 12‐bit analog input system. Some typical test results obtained with undamaged and damaged propellant samples are described.
Ion pair–ion pair and ion–dipole interactions in polyurethane–styrene blends
Authors: Rutkowska M. , Eisenberg A. 
Published: April 2003

AbstractIt is shown that ion pair–ion pair interactions can be utilized to achieve miscibility in blends of urethanes with styrene ionomers. The urethanes contain quaternary ammonium salts in the hard segments, while the styrenes contain sodium methacrylate groups (∼9.6 mol %). By contrast, ion–dipole interactions are not strong enough to achieve miscibility enhancement; a polyurethane containing short (ethylene oxide) sequences in the hard segment did not exhibit miscibility with a styrene–lithium methacrylate copolymer.
Mechanical and friction properties of glass‐filled thermoplastics modified by polyethylene additives
Authors: Lipatov Yu. S. , Petrenko S. D. , Privalko V. P. 
Published: April 2003

AbstractTemperature and concentration dependences of elasticity modulus, wear and wearability of industrial glass‐filled thermoplastics modified by low‐density polyethylene were studied. It is shown that polyethylene additive reduces the elasticity modulus in the solid aggregate state of polymer matrix and enhances it in the softening region. For the first time a possibility was found to reduce friction, wear, and wearability of glass‐filled thermoplastic materials by incorporating optimum amount of alloying polymer additive thermodynamically incompatible with the polymer matrix.
Ternary copolymers of hemin, styrene, and 1‐vinylimidazole or 1‐vinyl‐2‐methylimidazole as cyanide ion exchanger
Authors: Kokufuta Etsuo , Watanabe Hiroshi , Saito Kiyoshi , Nakamura Isei 
Published: April 2003

AbstractTernary copolymers, involving hemin (H) (ferri‐protoporphyrin IX chloride), styrene, and 1‐vinylimidazole (VI) or 1‐vinyl‐2‐methylimidazole (VMI) in the different proportions, were synthesized by radical copolymerization. All the copolymers obtained were insoluble in aqueous solvents. No dissolution of H from the copolymers was observed even when the extraction with 0.5N NaOH or HCl was allowed to continue for a total time of 50 days. To clarify the functional capabilities of the ternary copolymers as a cyanide ion exchanger, the adsorption of cyanide ion onto the copolymers was investigated at different pHs. The amount (Acn) of the adsorbed cyanide ion was found to be dependent on the content of H residue in the copolymer, thus indicating that the adsorption site for the cyanide ion consists of ferri‐protoporphyrin IX (FP). Another important feature is that Acn increases in proportion to the VI or VMI content of the copolymer. This result was discussed in terms of the coordination structure of the FP and also of the coordination reaction of cyanide ion to the FP.
Determination of graessley's relaxation time in concentrated polymer solutions and melts
Authors: Quadrat Otakar , Prokopov´ Eva 
Published: April 2003

AbstractThe method consists of a comparison between experimental data and Graessley's theoretical function of the dependence of viscosity of concentrated polymer solutions and melts on the velocity gradient in a linearized plot using a three‐parameter empirical equation. The procedure is objective and allows the use of a computer.
Effects of uniaxial drawing and heat‐treatment on gas sorption and transport in PVC
Authors: El‐Hibri M. J. , Paul D. R. 
Published: April 2003

AbstractSorption and transport measurements for various gases in rigid poly(vinyl chloride) were made following uniaxial drawing and heat treatment. The permeabilities of He, Ar, N2, and CH4 were found to be essentially independent of pressure in PVC while CO2 showed a complex pressure dependence which varied with prior exposure and degassing history. Sorption isotherms were analyzed by the dual mode sorption model, and the parameters obtained were correlated with the Lennard–Jones potential‐well depth of the gas. The Henry's law coefficient for CO2 was found to be significantly larger than expected which is believed to be the result of a specific interaction with PVC. Uniaxial drawing of PVC above its glass transition caused significant reductions in gas permeabilities, of which roughly one‐third is attributable to the accompanying heat treatment rather than molecular orientation per se. The physical state of the polymer was characterized by density, birefringence, and calorimetry. Changes in gas sorption and permeation behavior are discussed in terms of these results.
Optimization of batch polymerization processes—narrowing the MWD. II. Experimental study
Authors: Louie Brian M. , Soong David S. 
Published: April 2003

AbstractProgrammed solvent injection was previously proposed and analyzed in the first part of this two‐paper series as a viable alternative for controlling the average molecular weight and narrowing the polydispersity of products from a free‐radical polymerization process with an inherent tendency to exhibit strong gel and glass effects. Here, methyl methacrylate is chosen for experimental verification of this idea. The product molecular weight distribution is indeed narrowed.
Surface characterization of styrene/acrylamide copolymer latex particles
Authors: Tamai H. , Murakami T. , Suzawa T. 
Published: April 2003

AbstractSurface characteristics of styrene/acrylamide copolymer latex particles prepared without emulsifier were investigated as a function of acrylamide fraction in charged monomers. The presence of swelling or water‐soluble polymer layer at the particle surface was suggested, and its thickness increased with increasing acrylamide fraction. The surface charge densities by conductometric and potentiometric titrations wer about half that of polystyrene latex particles at low pH and they increased slightly with increasing pH. Regarding the heterocoagulation between styrene/acrylamide copolymer latex particles and polystyrene latex particles, the critical coagulation concentration of KCI decreased with increasing acrylamide fraction. The consideration in terms of the interaction due to electrostatic and van der Waals forces also suggested that the swelling or water‐soluble polymer layer at the particle surface plays an important role.
The application of coherent optics to the study of adhesive joints II. Holographic interferometry
Authors: Vallat M. F. , Smigielski P. , Martz P. , Schultz J. 
Published: April 2003

AbstractThe technique of holographic interferometry is complementary to the technique of speckle photography described previously. It allows the out‐of‐plane motion to be visualized with a sensitivity of about 0.3 μm. This technique has been applied to the study of the behavior of model glass‐glass joints bonded by different adhesives under shear stress. Its high sensitivity allowed the presence of stress concentrations at the ends of the joints to be shown in the case of high‐modulus adhesives and the existence of additional torsion and/or cleavage stresses to be demonstrated in the case of lower modulus adhesives. Work in progress should lead to more quantitative data.
Polymeric reaction of acrylic polymer–monomer system irradiated by low‐energy electron beam. II. Effect of ester structure of acrylic polymer
Authors: Takiguchi Ryohei , Uryu Toshiyuki 
Published: April 2003

AbstractPolymeric reactions of polyacrylate–benzyl acrylate (BzA) systems induced by a low‐energy electron beam were investigated by changing the species of polyacrylates added to the system. The gel fraction, the proportion of BzA units incorporated into gel by infrared (IR) analysis, and the molecular weight and its distribution curves by gel permeation chromatography (GPC) were examined to elucidate the reaction mechanism for the polymer–monomer system. The GPC curves were detected by both ultraviolet (UV) and refractive index (RI). As the UV‐detected GPC curves represent the benzyl groups of graft polymers and homo polymers, the polymerization reactions can be followed by GPC. Ester structures of acrylic polymers were varied in order to examine how much the ester group affects such individual reactions as crosslinking, graft polymerizations, and homopolymerizations. In the case of both polyisobutylacrylate–BzA and poly(isoamyl acrylate)–BzA systems, the crosslinking and graft reactions predominated, while in the case of poly(t‐butyl acrylate)–BzA systems, homopolymerization was the main reaction. These results can be explained by the structure and reactivity of polymer radicals and viscosity of the system.
Behavior of cyanoethylated cotton towards gamma radiation
Authors: Hebeish A. , Zahran A. H. , El‐Naggar A. M. Kh. 
Published: April 2003

AbstractUnmodified cotton fabric, cyanoethylated cottons having 0.12, 0.55, 0.77, and 1.24% N as well as cotton treated with NaOH under conditions similar to those of cyanoethylation but in absence of acrylonitrile were exposed to gamma radiation doses (3.199–31.199 Mrads). The six substrates before and after irradiation were assessed for copper number, carboxyl content, degree of polymerization, tensile strength, and elongation at break to determine the extent of degradation of these substrates. The effect of radiation dose on the nitrogen content of cyanoethylated cottons was also examined. It was found that degradation is higher the higher the radiation dose irrespective of the substrate used. Nevertheless, the extent of degradation is determined by nature of the substrate. Introduction of cyanoethyl groups in the molecular structure of cotton cellulose impart certain resistance to radiation degradation of cotton provided that these groups are present in appreciable amounts (0.55% N and above). The cyanoethyl groups seems to impede oxidation of the cellulose hydroxyls and/or glucosidic bonds against radiolysis. On the other hand, when present in smaller amounts, the cyanoethyl groups are not able to outweigh the increased accessibility of cotton cellulose brought about by the alkaline environment of the cyanoethylation reaction. Hence, substrates containing lower cyanoethyl contents are more susceptible to degradation than the modified cotton, and in this respect they are similar to alkali‐treated cotton.
Characterization of poly(vinyl alcohol)
Authors: Bugada Daniele C. , Rudin Alfred 
Published: April 2003

AbstractMolecular weight distributions, long chain branching frequency, and solution viscosities of samples of commercial poly(vinyl alcohol) (PVA) are reported. The PVA was fully reacetylated to poly(vinyl acetate) (PVAc) for characterizations by size exclusion chromatography using a low angle light scattering detector. The Mark–Houwink constants for PVAc in toluene were determined to be K = 0.106 cm3 g−1 and α = 0.59, at 25°C. Long chain branching frequency in the commercial PVAs studied was small and was little affected by polymer molecular weight. Some 95% or more of the branches in these species were short. Aqueous solutions at 10% (w/v) of PVA were Newtonian. The polymers examined differed in chemical composition, molecular weight distributions, and mean block lengths of vinyl acetate residues. Variations in a single characteristic, like a solution or intrinsic viscosity, cannot be used to deduce structural differences between PVAs.
Metal ion additive–polyimide interactions employing thermogravimetry
Authors: Rancourt J. D. , Taylor L. T. 
Published: April 2003

AbstractSolutions of poly(amic acid), a polyimide precursor prepared from 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride and 4,4′‐oxydianiline, containing metal ions such as Pd, Pt, and Sn in a variety of chemical states were prepared. The polymer–metal ion solutions and each component thereof were analyzed by thermogravimetry. Summation of the calculated contribution of each component of the polymer solution mass loss curve yields a calculated TG curve. Subtraction of the calculated curve from the actual curve for the polyamic acid–metal ion solution results in a difference TG curve. From the difference TG curve information about polymer/additive interactions can be obtained.
On the chain cross‐sectional area and motion of macromolecular chains
Authors: He Tian‐Bai 
Published: April 2003

AbstractThis paper attempts to relate the chain cross‐sectional area to the glass transition temperature of a polymer and to discuss the effect of the chain cross‐sectional area in view of the motion of molecular chains. It has been found that the definite relationship between glass transition temperature and cross‐sectionalarea can be obtained only when taking account of intermolecular interaction of polymer chains. It is considered that the chain cross‐sectional area will characterize the chain flexibility of a polymer since the glass transition temperature is related both to intermolecular interaction and chain flexibility of a polymer. The concept of the structural parameter cross‐sectional area per chain, first introduced by Vincent1 and used by Boyer and Miller,2–5 is useful in empirically correlating properties and structures of polymers. The glass transition temperature is a basic parameter of bulk polymers and is characteristic of their intermolecular interactions and chain flexibility. This paper attempts to relate chain cross‐sectional areas to glass transition temperatures of polymers and to discuss the effect of the chain cross‐sectional area in view of the motion of molecular chains.
Viscoelastic properties of elastic polyurethaneureas in the curing process
Authors: Raszczuk A. , Kozakiewicz J. , Orzechowski A. 
Published: April 2003

AbstractDynamic viscoelastic properties of a system, NCO‐terminated polyurethane–aniline–cresol–formaldehyde liquid resin were studied during the curing process using an R‐17 Weissenberg Rheogoniometer. For gel time determinations a new method was developed, the gel time being then difined as the cure time when the relaxation time τ = 3 s at a frequency of 0.1 Hz was achieved. The dynamic storage modulus G′, the dynamic viscosity η´ and the relaxation time τ have been determined as functions of curing time. The effects of cure temperature and of curing agent concentration on G′, η′, and τ were studied. The influence of cure temperature on the gel time and on the visco‐elastic properties determined at 18ks (5 h) of curing was discussed. Based on the experimental results, it was concluded that curing at higher temperature led to the more crosslinked polymer. Activation energy values for the gel time were also determined and compared with the values for polyurethanes and polyurethaneureas reported elsewhere. A relationship between the relaxation time and the effect of frequency on modulus G′ was presented, and it appeared to be independent of cure temperature, curing agent concentration, and curing time, being then presumably a useful method for comparative studies of viscoelastic behavior of different materials in curing process. This relationship was compared with the approximate relationship between tan δ and d In G′/d In ω given by Staverman and Schwarzl. The agreement at shorter relaxation times and some discrepancy at longer times were obtained.
Effect of structural changes of cotton by acid hydrolysis and crosslinking on soiling and soil release
Authors: Hebeish A. , Nasr H. I. , Abdou L. A. , El Sheltawi S. T. , Haggag K. 
Published: April 2003

AbstractThe effect of acid hydrolysis (0.5N HC1 at 60°C for 5–90 min) on the soiling and soil release properties of cotton fabric before and after crosslinking was investigated. The effect of acid hydrolysis of crosslinked cotton under similar condition on the same properties was also undertaken. Crosslinking with and without nonionic softener was carried out using dimethylol dihydroxyethlene urea and magnesium chloide hexahydrate as a catalyst. Aqueous and nonaqueous oily dispersions of carbon black were used for soiling. Results of these studies disclosed that acid hydrolysis prior to crosslinking imparted aqueous and oily soil resistance to the cotton, particularly during the very initial stages of hydrolysis treatment. Crosslinking of cotton and acid‐treated cottons in the absence of softener accentuated soil resistance. The opposite holds true for crosslinking in the presence of softener. Short acid treatment of cotton before and after corsslinking decreased the ability of cotton to release the aqueous and oily soils. On the other hand, acid hydrolysis of crosslinked cotton improved aqueous and nonaqueous soil‐resistance provided that the duration did not exceed 30 min. Hydrolysis accentuated also the ease of oily soil removal, but aqueous soil release was adversely affected. The results were interpreted in terms of changes in the physical and chemical structures of cotton and crosslinked cottons brought about by acid hydrolysis.
Rheological properties, shrinkage and melt spinning instability of blends of linear polyolefins with low density polyethylene
Authors: Santamaria Anton , White James L. 
Published: April 2003

AbstractA comparative study is presented of the influence of addition of a long chain branched low density polyethylene LDPE on the rheological and processing characteristics of a high density polyethylene (HDPE), a polypropylene (PP), and a polybutene‐1 (PB). The influence of the LDPE on the PP and PB are most striking. Substantial increases in normal stresses, “shrinkage” of extruded filaments, and melt spinning stability are observed. The effects are much smaller for the HDPE blends.