bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modification of cation exchange membrane by grafted poly(4‐vinyl‐N‐methylpyridinium‐iodide)
Authors: Shimasaki Kazuhiro , Ihara Hirofumi , Mizutani Yukio 
Published: April 2003

AbstractIt is well known that cation exchange membranes, having a very thin layer of a cationic polyelectrolyte on the membrane surface, have preferential permselectivity for monovalent cations in a monovelent‐divalent cations system. We studied the relationship between preferential permselectivity and molecular structure of the cationic polyelectrolyte. Grafted poly(4‐vinyl‐N‐methylpyridinium‐iodide) was used and was compared with poly(4‐vinyl‐N‐methylpyridiniumiodide). The backbone polymers were poly(styrene‐co‐p‐benzylstyrene) and poly(benzyl), onto which 4‐vinylpyridine was grafted by anionic polymerization and then quaternized with CH3I. The grafted poly(4‐vinyl‐N‐methylpyridinium‐iodide) is effective in making the cation exchange membrane preferentially permselevtive for Na+ ‐ Ca2+ system and is more preferable than poly(4‐vinyl‐N‐methylpyridinium‐iodide) in terms of electric resistance of the membrane. However, the relationship between the molecular structure of the cationic polyelectrolyte and the durability of the preferential permselectivity is not clear.
Determination of paper sheet fiber orientation distributions by a laser optical diffraction method
Authors: Yang C.‐F. , Crosby C. M. , Eusufzai A. R. K. , Mark R. E. 
Published: April 2003

AbstractThe combination of the laser and optical diffraction analysis provides a powerful tool for the determination of fiber orientation distribution in any paper sheet of basis weight low enough to be translucent to the laser beam. The coherent light beam from the laser is diffracted by the sample. It undergoes a Fourier transform from which the orientation distributions can be calculated. Measurements were made on 14 different samples of various degrees of orientation, including an essentially random handsheet as a control. The cross‐direction/machine direction elastic modulus ratios of the samples were found to correlate well with the distribution functions fitted to the orientation data. The correlation curve was S‐shaped, with a drastic drop in the modulus ration in the medium range of fiber orientation.
Benzoyl peroxide as a crosslinking agent for polyethylene
Authors: Kampouris E. M. , Andreopoulos A. G. 
Published: April 2003

AbstractThe efficiency of benzoyl peroxide (BPO) as a crosslinking agent for polyethylene (PE) was studied as a function of concentration and temperature in relation with the resin melt flow index and particle size. The investigation can lead to the selection of suitable materials and operating conditions for a proper crosslinking process. The decomposition characteristics of the initiator studied can be regulated in order to allow faster production rates when crosslinked PE are prepared by injection molding.
The effect of resin chemistry on the curing behavior and chemorheology of unsaturated polyester resins
Authors: Lee Dai‐Soo , Han Chang Dae 
Published: April 2003

AbstractThe effect of the structure of unsaturated polyester resin on its curing and rheological behavior during isothermal cure has been investigated, using three different grades of resin. In the investigation, the structure of the resins was determined, using nuclear magnetic resonance spectrometry (NMR), together with chemical analysis. Both a differential scanning calorimeter (DSC) and an infrared (IR) spectrometer were used to determine the curing kinetics, and a cone‐and‐plate rheometer was used to determine the variation of rheological properties during isothermal cure. On the basis of the experimental study, we have concluded: (1) at the same styrene‐to‐fumarate mole ratio, the resin having isophthalates cures slower than the one having none; (2) everything else being equal, the resin having a high styrene‐to‐fumarate mole ratio cures faster than the resin having a low one; (3) the higher the concentration of initiator, the faster a resin cures. It has been found that a resin that cures faster does not necessarily achieve a higher final degree of cure than one that cures slowly. We have found that a mechanistic kinetic model developed in our previous investigation is very useful for investigating the reactivity of unsaturated polyester resin, by determining the rate constant and activation energy of the propagation reaction. On the basis of rheological investigation, we have concluded that both tη∞ determined from steady shearing flow measurement and ttan δ = 1 determined from oscillatory shearing flow measurement may be used as a measure of gel time.
The influence of resin characteristics on the high speed melt spinning of isotactic polypropylene. II. On‐line studies of diameter, birefringence, and temperature profiles
Authors: Lu Fu‐Min , Spruiell Joseph E. 
Published: April 2003

AbstractAn investigation was carried out of the high speed melt spinning of three polypropylene resins with melt flow indices of 12, 35, and 300. On‐line measurements were made of diameter, birefringence, and temperature as a function of distance from the spinneret for a range of spinning conditions for each polymer. A plateau (decrease of cooling rate) in the temperature profile was associated with the occurrence of crystallization in the spinline. The position of this plateau correlated with a rapid rise in the birefringence profile and a rapid decrease in the rate of drawdown in the diameter profile. The temperature and birefringence profiles were used to determine the temperature and position on the spinline at which the onset of crystallization occurred. It was found that the position and temperature of crystallization onset varied considerably with changes in take‐up velocity, extrusion temperature, and resin melt index (weight average molecular weight). The crystallization onset occurred nearer the spinneret and at higher temperatures with (1) an increase of take‐up velocity, (2) a decrease of extrusion temperature, or (3) a decrease of resin melt flow index. An analysis was carried out to estimate the rate of stress development with distance along the spinline; the results were also used to estimate the stress at the onset of crystallization for each spinning condition. It was concluded that the observed behavior could be attributed to the role of spinline stress in producing molecular orientation and consequent increase of crystallization rate.
Improvement of plasma etching durability of positive working resist by copolymerization, blending, and crosslinking
Authors: Ueno Nobuo , Doi Yasunori , Sugita Kazuyuki , Sasaki Shigeru , Nagata Shiro 
Published: April 2003

AbstractThe plasma etching durability of O2 and CCl4 was investigated for copolymer and polymer blend of poly(methyl methacrylate) (PMMA) and poly(α‐methylstyrene) (PMSt) as a function of MSt content. Further, the effects of crosslinking on plasma etching were studied by incorporating N‐methylolated methacrylamide into the copolymer as a crosslinkable site during prebaking. The plasma‐etching resistance of PMMA was largely improved by incorporating or adding only a small amount of MSt. Especially in the case of the CCl4 plasma etching, the copolymer and the polymer blend with 10 mol% of MSt showed etching resistance as great as that of PMSt homopolymer. Stabilization of the polymers against the plasma etching can be explained by the sponge effect, the energy migration followed by the quenching by the phenyl ring. The polymer blend offered similar etching resistance as the copolymer, indicating an effective occurrence of the energy migration between the polymer chains. Etching resistance was also improved by crosslinking, also due to the enhancement of the sponge effect.
Experimental investigation of vinyl chloride polymerization at high conversion—temperature/pressure/conversion and monomer phase distribution relationships
Authors: Xie T. Y. , Hamielec A. E. , Wood P. E. , Woods D. R. 
Published: April 2003

AbstractAn equilibrium model relating temperature, pressure, monomer conversion and monomer phase distribution for vinyl chloride polymerization has been developed. This model can be used to determine the monomer conversion beyond the pressure drop by measurement of reactor temperature and pressure. It can also be used to estimate monomer conversion at the pressure drop point and the distribution of monomer in all the phases over the entire extent of polymerization. A series of experiments to measure the solubility of VCM in water and PVC were carried out in the temperature range 40–70°C. Correlations of the solubility of VCM in water and the VCM–PVC interaction parameter with temperature, respectively, were obtained from the experimental data.
ESCA and FT‐IR studies on boundary‐phase structure between blend polymers and polyamide substrate
Authors: Kodama Minekazu , Kuramoto Kazuo , Karino Isamu 
Published: April 2003

AbstractElectron spectroscopy for chemical analysis (ESCA) and Fourier‐transform infrared (FT‐IR) attenuated total reflection (ATR) studies have been made on the film of blend polymers consisting of poly(hydroxypropyl ether) of bisphenol A (P) and poly(ethylene oxide) (E) or P and poly(ethylene adipate) (A) formed on nylon‐6 (Ny) substrate to investigate the boundary‐phase structure between the substrate and the polymer blends. For the case of P/A blend, A is enriched to the depths probed by both ESCA (below ca. 60 Å) and FT‐IR‐ATR (below ca. 0.7 μm) from the nylon‐6 surface. For the P/E blend, though P is enriched to the depth probed by ESCA from the Ny surface, the enrichment of neither of the blend components can be found to the depth probed by FT‐IR‐ATR. These results indicate the different susceptibility between P/A and P/E blends to the influence from the Ny substrate.
Protein‐reactive, molded polystyrene surfaces having applications to immunoassay formats
Authors: Chu Victor P. , Tarcha Peter J. 
Published: April 2003

AbstractInjection‐molded polystyrene surfaces were chemically modified rendering them protein reactive. The process involves chlorosulfonation of the aromatic ring, sulfonamide formation with excess di‐ and triamines, and reaction of the residual pendant amines with various bifunctional molecules. Surfaces possessing pendant bromoacetyl, iodoacetyl, fluorodinitrophenyl, and trimellitic anhydride were prepared and can exhibit up to ten times more protein immobilization capability compared to unfunctionalized polystyrene, where the coupling takes place presumably via hydrophobic interaction.
Time–temperature–transformation (TTT) cure diagrams: Relationship between Tg and the temperature and time of cure for a polyamic acid/polyimide system
Authors: Palmese G. R. , Gillham J. K. 
Published: April 2003

AbstractGlass transition temperatures (Tg) were obtained vs. isothermal temperature (Tcure) and time of cure for a polyamic acid/polyimide system. A time–temperature–transformation (TTT) isothermal cure diagram was constructed to include the time to vitrification and iso‐Tg curves. As for expoxies, the relationship between Tcure and the time to vitrification is S‐shaped. Plots of Tg vs. Tcure show that solvent evaporation and chemical reaction are controlled by vitrification.
Cooling and annealing properties of copolymer‐type polyacetals and its crystallization behavior
Authors: Chiang Wen‐Yen , Lo Ming‐Song 
Published: April 2003

AbstractCopolymer‐type polyacetals (POMs) that have been cooled at seven different rates from the melt at 180°C to the solid at 23°C show average spherulite diameters from 10 to 25 μm on an etched fracture surface using scanning electron microscopy (SEM). The wide‐angle X‐ray diffraction (WAXD) of POM displays a degree of crystallinity ranging from 60 to 66% by applying the two‐phase model. From studies of mechanical properties, physical properties, and dielectric dissipation factor (tan δ), we found that POM with a faster cooling rate shows looser packing and smaller spherulites on the fracture surface than that with a slower cooling rate. This conclusion is in agreement with the observations made on SEM and WAXD. DSC measurements were used to measure the heat of fusion, melting point, and crystallization temperature of POMs. An equilibrium melting temperature was estimated from the Hoffman–Weeks plot. The overall crystallization kinetics of POMs were analyzed by the Avrami equation. Results for the Avrami exponent n, between 2 and 3, indicate small disklike spherulites following nucleation growth kinetics. Annealing the cooled POM at 150°C results in recrystallization featuring a significant increase in the average diameter of spherulites in SEM.
Synthetic resins. V. Preparation and properties of substituted benzoic acid, hydroxyacetophenone and aniline/formaldehyde resins
Authors: Das Anil P. , Nayak Padma L. , Lenka Subasini 
Published: April 2003

AbstractA number of resin copolymers have been prepared by condensation of substituted aromatic compounds with formaldehyde in the presence of different acid catalysts. The resin copolymers were characterized by IR, thermal, X‐ray diffraction, and by their reactivity ratios. The resins were found to possess high thermal stability. Activation energies of resin degradation were computed using the Freeman–Anderson method. The antifungal activities of several previously synthesized resins were studied.
Water‐dispersible graft copolymer mixtures prepared by electron irradiation. I. Polymerization behavior
Authors: Egusa Shigenori , Sasaki Takashi , Hagiwara Miyuki 
Published: April 2003

AbstractHighly viscous systems made up of 70 wt% epoxy resin dissolved in 30 wt% monomer mixtures of acrylic acid and styrene were irradiated with 1.5 MeV electrons to initiate graft copolymerization. The temperature measurement of the systems reveals that the polymerization reaction takes place both during and after the electron‐beam exposure of about 5‐sec duration. The reaction lasts about 50 sec for a low beam current of 0.6 mA, while for a high beam current of 6.0 mA it lasts merely about 20 sec. The gel permeation chromatography (GPC) measurement of obtained products demonstrates that the molecular weight distribution of ungrafted copolymer of acrylic acid and styrene becomes strikingly broader as the beam current is lowered. The GPC data suggest that the fraction of epoxy resin having a grafted branch increases with an increase in the beam current. All of these results are interpreted in terms of the mobility and the concentration of reactive species such as polymer radicals and low molecular weight free radicals.
Water‐dispersible graft copolymer mixtures prepared by electron irradiation. II. Dispersion behavior
Authors: Egusa Shigenori , Sasaki Takashi , Hagiwara Miyuki 
Published: April 2003

AbstractHighly viscous systems made up of 70 wt% epoxy resin dissolved in 30% monomer mixture of styrene and acrylic monomers were irradiated with 1.5 MeV electrons to initiate graft copolymerization. The obtained product of graft copolymer mixture was fed into a mixed solvent of n‐butanol and cyclohexanone, and was heated 2 h at 70°C to form a predispersion. Then aqueous solution of 2‐dimethylaminoethanol or ethanol was added to the predispersion, thus giving a stable dispersion in water or in ethanol. The particle diameter of the aqueous and ethanol dispersions is practically the same, thus suggesting that polymer particles are virtually generated during the predispersing procedure, and at this step the size of the particles is actually determined. The particle diameter increases inversely proportional to the polymer concentration in the predispersion. Furthermore, the particle diameter shows a tendency to decrease with an increase in the hydrophilicity of monomers used in the graft copolymerization. The stopped‐flow measurement, on the other hand, reveals a characteristic pH dependence of the dispersion stability to the addition of NaCl. This result is interpreted based on a particle model consisting of a particle core of epoxy resin and its surrounding layer of acrylic copolymer.
Morphology of hydroxyapatite as suspension stabilizer in the polymerization of poly(styrene‐co‐butadiene)
Authors: Deslandes Yves 
Published: April 2003

AbstractThe morphology of the layer of hydroxyapatite that surrounds the polymer beads during the suspension polymerization of a random copolymer of styrene and butadiene is described. The layer is actually composed of two distinct parts: a thin layer made of very uniformly distributed hydroxyapatite primary particles and a second layer, usually much thicker, which is made of agglomerates of hydroxyapatite which are loosely packed. This second layer contains very small polymer beads, about 1 to 2 microns in diameter, that have polymerized at the droplet interface. Some of these smaller beads migrate into the bulk of the polymer during the polymerization contributing to the contamination of the polymer.
Wide‐angle x‐ray scattering study of heat‐treated peek and peek composite
Authors: Cebe Peggy , Lowry Lynn , Chung Shirley Y. , Yavrouian Andre , Gupta Amitava 
Published: April 2003

AbstractWe report the results of a study of poly(etheretherketone) (PEEK) neat resin and APC‐2 carbon fiber composite samples which were processed from the melt and then subjected to a variety of thermal treatments. Wide‐angle x‐ray scattering was used to study the effects of quenching and annealing treatments. For both neat resin and composite, annealing resulted in perfection of the crystalline microstructure. In addition to the crystalline and amorphous scattering usually observed, disorder is frozen‐in by fast cooling after heat treatment. The disordered component is detected as an additional low‐angle scattering peak at 14 degrees, well separated from the crystalline reflections, and is observed in low molecular weight material synthesized in our laboratory, and in commercially available neat resin PEEK and APC‐2 carbon fiber composite samples. When disordered material was subsequently heated above the glass transition, and then cooled very slowly, only the crystalline and amorphous scattering remained. Application of stress also resulted in formation of the disorder in the necked down regions of samples drawn in tension, suggesting that residual stresses may occur as a result of rapid cooling after heat treatment.
Mechanisms of antioxidant action: The effect of spin traps during the processing and photooxidation of PVC
Authors: Adeniyi J. B. , Al‐Malaika S. , Scott G. 
Published: April 2003

AbstractIt is demonstrated by the use of spin traps that during the early stages of thermal processing of PVC considerable concentrations (> 3 × 10−6 mol g−1) of free radicals are produced which are primarily responsible for the initial products (hydroperoxides, unsaturation, and hydrogen chloride) previously shown to be formed in the polymer. From a semiquantitative analysis of these products, it is estimated that more than 50% of the radicals are formed from hydroperoxides and the rest by mechanoscission of the polymer chain. The spin traps are effective processing stabilizers in combination with a tin maleate HC1 scavenger. One of them (2‐methyl‐2‐nitroso propane, MNP) has also been shown to be a photoantioxidant.
Novel thin‐film composite membranes containing photoreactive groups part I: Choosing the photoreactive group
Authors: Chadda S. K. , McCarry B. E. , Childs R. F. , Rogerson C. V. , Tse‐Sheepy I. O. , Dickson J. M. 
Published: April 2003

AbstractThin‐film composite membranes containing photoreactive groups have been developed. The presence of these groups facilitates the subsequent photochemical conversion of the membrane to include a range of different chemical moieties. For example, a cationic or an anionic membrane can be made from the same initial composite membrane. In this paper the selection of an appropriate photolabile group is investigated.
The reduction of orientation in fibers spun from two‐phase polymer blends via the introduction of shear into elongational flow by the presence of a second phase
Authors: Miles I. S. 
Published: April 2003

AbstractA model is proposed for the reduction of orientation in spun fibers of two‐phase polymer blends. This is based on the introduction of shear into an elongational flow by the presence of a second phase. The requirement is that the dispersed phase should not deform to the same extent as the continuous phase so that the flow field in the region of each particle is perturbed. Around an isolated droplet of minor component, the shear rate in the continuous phase goes through a maximum when the extension rate in the droplet is around half that macroscopically imposed. The dependence of orientation reduction on concentration of dispersed phase is fitted well by assuming that the flow field around a particle is disturbed over a distance two to three times the particle diameter. In this case the maximum average shear rate around the particle is of the same order of magnitude as the elongation rate. The model proposed is consistent with all the observed features of orientation reduction during spinning of two‐phase blends.
Analysis of temperature‐dependent AC dielectric loss data
Authors: Bánhegyi György , Hedvig Péter , Karasz Frank E. 
Published: April 2003

AbstractThe analysis of dielectric loss data is frequently complicated by the presence of ohmic conductivity, especially at lower frequencies. Two simple methods are discussed for locating transition temperatures and for determining activation energies in such cases. In the first method the permittivity derivative [dε′(T)/dT] is used; in the second, permittivity difference spectra ε′(T, v1) – ε′(T, v2) (v1 ≪ v2 are used. The latter technique, however, cannot be used for activation energy determination. The theoretical basis of these methodologies and an analysis of representative experimental data are presented. The data set include measurements of pure and filled polyurethanes and of radiation‐cured unsaturated polyester resins. Finally, the advantages of data presentation in the form of ε′ and ε″ instead of tan δ are discussed.
Synthesis, physical and thermal characterization of phosphorus‐containing homopolymers and copolymers based on 2,4‐bis(4‐aminophenoxy)‐6‐diethoxyphosphinyl‐s‐triazine
Authors: Melissaris Anastasios P. , Mikroyannidis John A. 
Published: April 2003

AbstractNovel phosphorus‐containing homopolyimides, homopolyamides, and homopolyureas were prepared by reacting 2,4‐bis(4‐aminophenoxy)‐6‐diethoxyphosphinyl‐s‐triazine (BADT) with pyromellitic or benzophenone tetracarboxylic dianhydride, terephthaloyl chloride, and tolylene diisocyanate, respectively. In addition, the corresponding copolymers that contained approximately 3% phosphorus were prepared by reacting BADT and 4,4′‐diaminodiphenyl sulfone with the aforementioned reagents. These polymers were characterized by inherent viscosity measurements, infrared (IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy as well as by differential thermal analysis (DTA) and dynamic thermogravimetric analysis (TGA). Their thermal properties were compared with those of the corresponding nonphosphorylated polymers. The copolymers were stable up to 233–272°C in nitrogen or air atmosphere. The homopolymers showed a relatively lower thermal stability. Furthermore, a model diimide, diamide, and diurea were synthesized from the reactions of BADT with phthalic anhydride, benzoyl chloride, and phenyl isocyanate, respectively. The physical and thermal characteristics of these model compounds were correlated with those of the corresponding homopolymers.