bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solution NMR study of the post‐polymerization crosslinking agent N,N′‐(2‐propyloximino)‐4,4′‐methylenebis(phenylcarbamate). I
Authors: Bassett Walter H. , Sun Tong , Porter Roger S. 
Published: April 2003

AbstractBecause of its possible use as a blocked “post‐polymerization crosslinking agent” for polymers containing labile hydrogen, the structure of the acetone oxime adduct of 4,4′‐methylenebis‐(phenylisocyanate) has been determined. 13C and 1H nuclear magnetic resonance (NMR) spectroscopy has identified this product to be N,N′‐(2‐propyloximino)‐4,4′‐methylenebis(phenylcarbamate). Chemical shift assignments were based on information obtained by proton decoupled, off‐resonance decoupled, and gated decoupled 13C‐NMR, proton‐NMR, and semiemperical substituent chemical shift (SCS) parameters.
An NMR study of the dissociation of N,N′‐(2‐propyloximino)‐4,4′‐methylenebis(phenylcarbamate) and its crosslinking of polymers containing labile hydrogens. II
Authors: Sun Tong , Bassett Walter H. , Porter Roger S. 
Published: April 2003

AbstractNuclear magnetic resonance spectroscopy has been used to study the dissociation and reaction of N,N′‐(2‐propyloximino)‐4,4′‐methylenebis(phenylcarbamate), as a crosslinking agent for polymers containing labile hydrogens. The crosslinking of poly(acrylic acid), polyacrylamide, and poly(vinyl alcohol) was found to result upon heating each to 150°C for 10 min with this component at 2–10 wt %.
Structure–property relationships of anionic exchange membranes for Fe/Cr redox storage batteries
Authors: Arnold Charles , Assink Roger A. 
Published: April 2003

AbstractMembranes with lower area resistivity, higher selectivity, and reduced susceptibility toward fouling were required to improve the efficiency and lifetime of Fe/Cr redox storage batteries. The relationship of membrane structure to these electrochemical properties was not well understood. To gain a better understanding of structure–property relationships, a series of model membranes was synthesized in which the degree of crosslinking, ion exchange capacity, and porosity could be varied independently. This permitted the completion of several factorial studies in which the effect of each structural variable and interaction between variables could be defined and quantified. It was found that increasing the ion exchange capacity had a beneficial effect on all three electrochemical properties. Increasing the porosity reduced the resistivity and fouling but resulted in poorer selectivity. The degree of crosslinking had no effect on resistivity but improved selectivity and reduced fouling was observed when this parameter was increased. These relationships are consistent with theoretical models that have been proposed to account for the behavior of ion exchange membranes in general. From this data, empirical models were constructed which could be used to predict the area resistivity and water content of other anionic exchange membranes.
Controlled degradation of polystyrene
Authors: Ide Syoaki , Ogawa Taichi , Kuroki Takeshi , Ikemura Tadashi 
Published: April 2003

AbstractFor the purpose of efficient utilization of waste polystyrene, the recovery method of a styrene oligomer having a molecular weight of 1000–3000 was studied. Thermal and catalytic degradations were carried out. It was impossible to obtain a styrene oligomer with a molecular weight less than 5000 by thermal degradation in the temperature range of 300–500°C. Catalytic degradation in the presence of silica–alumina catalyst in the temperature range of 190–230°C made it possible to control the decrease in molecular weight and to obtain a styrene oligomer having a molecular weight of 500–3000. Simultaneously, the molecular structures of the reaction products from thermal and catalytic degradations were determined by NMR analysis.
Procedure for evaluation of the Mark–Houwink constants
Authors: Dobkowski Zbigniew 
Published: April 2003

AbstractAn iterative procedure for evaluation of the Mark–Houwink constants, using the GPC universal calibration principle and the extended [η]–M relationship, is described. The procedure is recommended for newly prepared polymers of unknown average molecular weights. An example is given for bisphenol C‐2 polycarbonate.
Immobilization of cellulase using porous polymer matrix
Authors: Kumakura Minoru , Kaetsu Isao 
Published: April 2003

AbstractA new method is discussed for the immobilization of cellulase using porous polymer matrices, which were obtained by radiation polymerization of hydrophilic monomers. In this method, the immobilized enzyme matrix was prepared by enzyme absorbtion in the porous polymer matrix and drying treatment. The enzyme activity of the immobilized enzyme matrix varied with monomer concentration, cooling rate of the monomer solution, and hydrophilicity of the polymer matrix, taking the change of the nature of the porous structure in the polymer matrix. The leakage of the enzymes from the polymer matrix was not observed in the repeated batch enzyme reactions.
Polymerization of tung oil by reaction of phenols with tung oil
Authors: Yoshimura Yukio 
Published: April 2003

AbstractInvestigation was made on the mechanism of polymerization in reactions of tung oil and phenols in the presence of an acid catalyst. It was made by means of comparative HLC and NMR analyses of the products of tung oil self‐polymerization, other varied vegetable oil‐various phenol reactions, and tung oil‐various‐in‐functionality phenol reactions under given conditions. As a result, it was confirmed that polymerization in reactions of tung oil and phenols is attributed not to tung oil self‐polymerization but to di‐ or trialkylation, with tung oil, of phenols, which can serve as crosslinking agents of tung oil.
Luminescence emission of isotactic polypropylene
Authors: Osawa Zenjiro , Kuroda Hideyuki , Kobayashi Yutaka 
Published: April 2003

AbstractIn order to elucidate the origin of luminescent species in unstabilized commercial isotactic polypropylene (IPP), effects of hexane extraction and exposure of the extracted IPP film to the atmosphere on both fluorescence and phosphorescence emissions were examined. Fluorescence emission from the unextracted IPP film disappeared by the extraction, and only a very weak phosphorescence emission was found. During the exposure of the extracted IPP film to the atmosphere, both fluorescence and phosphorescence emissions appeared again. The intensity of the spectra increased with the exposure time and finally almost reached that from the unextracted IPP film. The results indicated that main fluorescent species in IPP are foreign impurities originating from an ambient atmosphere, and that contribution of a very minor amount of phosphorescence species such as carbonyl groups incorporated with the polymer was scarce.
Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. V. An isomerically related semi‐1‐interpenetrating polymer network system
Authors: Hourston D. J. , Zia Y. 
Published: April 2003

AbstractA series of polyurethane–poly(vinyl acetate) semi‐1‐IPNs were synthesized, and certain physical properties investigated. Electron microscopy showed all the materials to be substantially phase‐separated, but evidence from dynamic mechanical analysis indicated that some mixing occurred, because the polyurethane glass transition was shifted in both the tan σ− and the E″–temperature curves. The variation of modulus with composition was found to be reasonably close to the predictions of the Davies equation. When the exponent in that relation was changed to ⅙, a good fit was obtained. Synergism with respect to tensile strength was observed for two of the semi‐1‐IPNs. Stress–relaxation measurements, over a fairly narrow temperature range, were made on the semi‐1‐IPN containing 40% by weight of the polyurethane network. A master curve was constructed. It was noted that the WLF equation was not obeyed by this semi‐1‐IPN at temperatures above about 50°C.
Plasma polymerized membranes and gas permeability. I
Authors: Yamamoto Minoru , Sakata Jiro , Hirai Masana 
Published: April 2003

AbstractGas permeability of composite membrane prepared by plasma polymerization of various organic compounds was studied. In the membrane, a pinhole‐free polymeric thin film was formed on a porous substrate. This film below 0.2 μm in thickness had sufficient mechanical strength for gas separation. The composite membranes were recognized to have high permeability and high permselectivity. Especially, the membranes prepared from hexamethyldisiloxane showed high permeation rate for oxygen, and those prepared from 1‐hexene or cyclohexane showed high permselectivity between oxygen and nitrogen. chemical structure of plasma‐polymerized film prepared from hexamethyldisiloxane was similar to that of dimethylpolysiloxane with a crosslinking of the polymer. The high permeability and high permselectivity of this film is considered to be due to its structure as mentioned above.
The elastic moduli of particulate‐filled polymers
Authors: Theocaris P. S. , Sideridis E. 
Published: April 2003

AbstractThe static and dynamic elastic moduli of particulate composites, consisting of two phases, one of which has isotropic–elastic and the other linear viscoelastic properties, were studied. For this purpose a model defining the approximate equations for determining the elastic modulus of a composite from the properties of the constituent materials was used. Classical theory of elasticity was applied to this simplified model of a composite‐unit cell. The following assumptions are made: (i) filler particles are spherical; (ii) fillers are completely dispersed; and (iii) the volume fraction of fillers is sufficiently small, so that any interaction among fillers may be neglected. A class of iron‐filled epoxy composites was subjected to tests in order to compare the theoretical values with the experimental results. The elastic modulus calculated by the expression derived in this study seems to corroborate with the experimental results fairly well. Finally, by applying the correspondence principle to this expression, theoretical relationships for the dynamic storage and loss moduli were also derived.
Dimensional changes during solvent‐induced crystallization of poly(ethylene terephthalate) films
Authors: Durning Christopher J. , Rebenfeld Ludwig 
Published: April 2003

AbstractThe sample dimensional changes accompanying diffusion with induced crystallization in amorphous poly(ethylene terephthalate) (PET) films are analyzed. Initially, the film's lateral area remains practically constant, but near the end of the process, it increases rapidly, consistent with non‐Fickian models for diffusion. The ultimate relative thickness increase is about double that for the lateral dimension, implying that plastic deformation in the thickness direction accompanies the sorption. Plots of fractional area increase (ΔA/ΔA∞) vs. fractional weight gain (W/W∞) indicate severe softening of the polymer by the penetrant.
Improvement of hydrophilicity of polypropylene by liquid‐phase mutual irradiation of acrylics
Authors: Pugh Colleen , Hsieh You‐Lo 
Published: April 2003

AbstractN‐butanol was found to promote the inclusion of methyl acrylate and methyl methacrylate in polypropylene, but did not affect the uptake of acrylic acid in the polymer. Polymerization of the monomers was, however, not significantly affected by the use of this swelling agent. The monomer exchange process followed by a liquid phase mutual irradiation has proved to be very effective in enhancing the polymerization of all three monomers on polypropylene. Optimum radiation doses for effective polymerization of the monomers were found to be around 3.2 Mrad for methyl acrylate and around 4.8 Mrad for methyl methacrylate and acrylic acid. Surface wettability of the film and moisture regain of the fiber were tremendously improved with all monomers regardless of the swelling agent and temperatures. Also, a low radiation dose of 1.6 Mrad was as effective as the higher doses. Methyl acrylate and methyl methacrylate modified fibers showed no marked changes in strength and elongation, but did result in a harsher hand. Acrylic acid modified fibers increased greatly in elongation, decreased to a greater extent in strength, and softened in hand.
Surface characterization of styrene/2‐hydroxyethyl methacrylate copolymer latex
Authors: Shirahama Hiroyuki , Suzawa Toshiro 
Published: April 2003

AbstractStyrene/2‐hydroxyethyl methacrylate copolymer (PS/PHEMA) latex was prepared without soap. From an electron micrograph, this latex was found to be highly monodisperse. The surface characterization of PS/PHEMA latex was compared with that of polystyrene (PS) latex. Conductometric titration curves of these latexes revealed that both strong and weak acid groups existed on the latex surface. It was found that pH dependence of surface charges for these latexes was not very pronounced whereas negative values of ζ‐ potentials for PS/PHEMA latex were smaller than that for PS latex over the whole range of measured pH. This was interpreted on the basis of the difference in the structure of the electrical double layer for these latexes. Methylene Blue adsorption onto PS and PS/PHEMA latexes was measured as a function of pH, too. The pH dependence of the dye adsorption onto these latexes was hardly discernible. However, the amount of Methylene Blue adsorbed was somewhat greater onto PS latex than onto PS/PHEMA latex. This result might be attributed to the strength of hydrophobic interaction between dye and latex. It was suggested that PS/PHEMA latex was more hydrophilic than PS latex in spite of having about the same surface charge as PS latex.
Epoxy resin cure. I. Fluorine‐19 NMR of boron trifluoride monoethylamine and fluoroboric acid
Authors: Smith Robert E. , Larsen Fred N. , Long Charles L. 
Published: April 2003

AbstractFluorine‐19 NMR is used to examine the role of boron trifluoride monoethylamine (BF3–MEA) in epoxy resin cure. Spectra were first recorded in a variety of solvents suitable for dissolving different epoxy resins. All spectra contained a peak due to fluoroboric acid. Spectra of BF3–MEA in orthodichlorobenzene were then recorded at elevated temperatures. The floroboric acid peak area increased, indicating that the BF3–MEA was being hydrolyzed. Results indicate that, at temperatures above 100°C, BF3–MEA is completely hydrolyzed within 5 min to fluoroboric acid.
Saturated and unsaturated polyesters based on 1,3‐(dicarboxymethoxy)benzene
Authors: Shaaban A. F. , Hamed A. A. , El‐Karim I. A. G. 
Published: April 2003

AbstractSaturated polyesters were prepared by the reaction of 1,3‐(dicarboxymethoxy)benzene with ethylene, diethylene, tetramethylene, and hexamethylene glycols. Also, unsaturated polyesters were prepared by the reaction of 1,3‐(dicarboxymethoxy)benzene and maleic anhydride with the same glycols. All the polyester resins obtained have been characterized, and the unsatureated polyesters were found to cure with styrene. The properties of the cured polyesters in the form of films were determined. IR and 1H‐NMR spectroscopy were used for both qualitative and quantitative analyses of the polyesters as well as their hydrolyzate products, after curing with styrene.
Use of polymer‐bound metals as fire retardants in polyethylene–silicon blends
Authors: Schroll A. L. , MacLaury M. R. 
Published: April 2003

AbstractLead compounds and silicone gum when blended into polyethylene act as synergistic fire retardant. The incorporation of lead into the polymer network via lead carboxylate formation through polyethylene grafted with maleic anhydride has been studied as a means of improving the metal dispersion and flammability behavior. Lead was also incorporated directly into a polymer backbone via the formation of lead polyesters. The use of other metal compounds as fire retardant additives has also been studied. No special behavior was seen for polymer‐bound lead relative to non‐polymer bound lead, and other metals were not found to be effective replacements for lead in polyethylene graft maleic anhydride.
Resistivity behavior of carbon‐black‐filled silicone rubber in cyclic loading experiments
Authors: Kost J. , Narkis M. , Foux A. 
Published: April 2003

AbstractStress–relaxation and cyclic loading behavior of silicone/EC black vulcanizates have been measured at several strains up to 0.8. The first extension is always very different from the subsequent ones. Orientation effects of anisometric carbon particles are starting to play an important role only after a certain elongation has been exceeded. The conductive elastomers can be stabilized by mechanical preconditioning procedures involving cycling at high extensions. The stabilized specimens then behaved nearly reversibly when cycled at strains below about 50% of the previous preconditioning strain. The resistivity‐extension cycle consists of a single peak or a double peak per a strain peak depending on the strain level. The transition from single to double resistivity peaks depends on whether particle orientation takes place during the stretching process, which depends upon the level of strain.
Membrane structure and permeation properties of poly(vinyl chloride)/liquid crystal composite membrane
Authors: Kajiyama Tisato , Washizu Shintaro , Takayanagi Motowo 
Published: April 2003

AbstractA series of polymer/liquid crystal composite membranes, at several weight ratios, was prepared casting from a tetrahydrofuran solution of poly(vinyl chloride) (PVC) with N‐(4‐ethoxy‐benzylidene)‐4′‐butylaniline (EBBA). From the thermal analysis, microscopic observation, mechanical property, and gas permeation studies, the properties for a series of PVC/EBBA composite membranes were derived. DSC showed that PVC and EBBA were quite miscible and EBBA in composite membranes at below 30 wt % was molecularly dispersed without forming crystal domains. Morphological observations exhibited that EBBA molecules interpenetrated in a continuous phase among the 3‐dimensional spongy networks of PVC matrix in the case of the 40/60 (PVC/EBBA, in wt %) composite membrane. Stable retention of EBBA in the composite membrane and its high mechanical durability might arise from such an aggregation structure. The permeability coefficients to oxygen gas, P02 and nitrogen one, PN2 through the 40/60 (PVC/EBBA) composite membrane showed a discontinuous jump with a several–tenfold increase in the vicinity of the crystal–nematic transition temperature TKN of EBBA. The magnitudes of P02 and the separation factors P02/PN2 above TKN were of the order of 10−9 cm3 (STP) cm−1 s−1 cm Hg−1 and 2–3, respectively. The value of P02/PN2 reached a maximum just above TKN. The P02 − P02/PN2 relationship above TKN exhibited an unusual behavior as P02/PN2 increased with an increase in P02.
Synthesis and transport properties of thin film composite membranes. II. Preparation of sulfonated poly(phenylene oxide) thin film composite membranes for the purification of alberta tar sands waste waters
Authors: Huang R. Y. M. , Kim J. J. 
Published: April 2003

AbstractThin film composite membranes of sulfonated poly(phenylene oxide) (SPPO)–polysulfone (PS) (SPPO–PS) were prepared by coating the hydrogen or sodium form of SPPO onto various porous substrates such as polysulfone (PS). The effects of membrane preparation conditions and feed water variables on the salt rejection and production rates were investigated using reverse osmosis. Purification of the waste waters from the Alberta heavy oil fields for desalination and recycling use was carried out. Production rates and salt rejections for the various feeds were found to be in the range of 5–20 gfd (gallons/ft2 day) and 80–99% respectively at 600 psig and 20°C, depending on the experimental conditions and membrane properties.
Depolymerization of fluoroalkyl methacrylate polymers as studied with thermogravimetry
Authors: Hayakawa Kiyoshi , Kawase Kaoru , Yamakita Hiromi 
Published: April 2003

AbstractThermal behaviors of a few kinds of poly(fluoroalkyl methacrylate) prepared by γ‐or UV‐ray polymerization were investigated by using thermogravimetric measurements with the intermittent analysis of the gaseous products. The degradation of fluoroalkyl methacrylate polymers, monomeric units of which were CH2=C(CH3)COOCH2(CF2CF2)nH, n = 1, 2, and 3, proceeded according to the depolymerization mechanism reproducing the pristine monomer exclusively, but the thermogram in inert atmosphere showed the features of a two‐step reaction. Two species of polymer differing in the heat stability were supposed to exist in the polymeric substance produced by γ‐ or UV‐ray irradiation, and the fraction of polymer having lower heat stability increased with the increasing length of the fluoroalkyl ester group. In air, however, the thermogram of poly(fluoroalkyl methacrylate) showed no such a stepwise weight decrease as was observed in inert atomsphere with the elevating temperature, and the temperatures at which the depolymerization was introduced shifted to a much higher region. The results were ascribed to the reaction of initiating polymer radicals produced on polymer having lower stability with oxygen to form hydroperoxide, which once stabilized the polymer radicals and obstructed the initiaition of the unzipping reaction till higher temperature.
Dynamic mechanical properties of highly loaded ferrite‐filled thermoplastic elastomer
Authors: Saini D. R. , Shenoy A. V. , Nadkarni V. M. 
Published: April 2003

AbstractThe dynamic mechanical properties in terms of the storage modulus E′, loss modulus E″, and the loss tangent δ has been studied for highly filled magnetic polymer composites. The effect of surface treatment on the relaxation spectra has been clearly elucidated and quantitative values indicating the extent of polymer–filler interactions have been given. Various models have been tested for describing the viscoelastic behavior of such highly filled systems. The Wiechert model using a single‐arm with a Cole–Cole parameter has been shown to effectively fit the Argand diagram in the case of the present highly filled systems.
Structure–property relationship in heat‐set poly(ethylene terephthalate) fibers. III. Stress–relaxation behavior
Authors: Gupta V. B. , Ramesh C. , Gupta A. K. 
Published: April 2003

AbstractStress–relaxation studies between room temperature and 140°C were made on oriented multifilament poly(ethylene terephthalate) (PET) yarn and on four other samples which had been prepared by heat‐setting this yarn at 180 and 230°C while free to relax and when held taut at constant length. Using the time–temperature superposition principle, the data were superimposed, and the master curves of relaxation modulus were constructed for each sample; the relaxation–time spectra for these samples were computed using the Alfrey approximation. The results revealed that (i) the free‐annealed samples show higher visco‐elasticity than the corresponding taut‐annealed samples and (ii) the relaxation–time spectra show two prominent relaxation processes on logarithmic time scale in the case of all the samples; the two relaxations being more intense in the free‐annealed samples. These observations are interpreted in terms of fiber structure and morphology, which had been studied earlier; the amorphous orientation in the free‐annealed samples is low, and they have a more distinct separation of the crystalline and amorphous phases. These factors facilitate molecular relaxation processes in the non‐crystalline phase; the relaxation are therefore relatively more intense in these samples, and they exhibit more viscoelasticity.