bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of electrostatically stabilized poly(methyl methacrylate) latex
Authors: Chu Hou‐Hsein , Hsu Xue‐Chaun 
Published: April 2003

AbstractPoly(methy methacrylate) latex with various solid contents, stabilized electrostatically, was studied. The hydrodynamic layer (H.L.) extends rapidly at volume fraction larger than 0.35. The agglomeration of particles was found. When the reduced thickness (δ/r) of H. L. exceeds 3.0, particle agglomeration becomes more serious and the gel‐like product forms. In comparison, the value of (δ/r) is much smaller than 3.0 when the H. L. begins to contact each other. Using a higher amount of emulsifier, the thickness of H. L. decreases. This is attributed to the fact that more free emulsifier presenting in the aqueous phase leads to more depletion stabilization. Meanwhile, in the presence of unreacted monomer, the use of the monomer‐swollen volume fraction is suggested to replace the unswollen volume fraction. © 1994 John Wiley & Sons, Inc.
Dimethylacetamide sorption kinetics in a urethane/urea/ether block copolymer
Authors: Gou M. M. , Koros W. J. , Goldman G. 
Published: April 2003

AbstractPolymer solvent interactions in a block polyurethane/urea/ether polymer belonging to the spandex family are considered in this article. Independent analysis of the sorption isotherms for dimethylacetamide (DMAc) in the spandex spandex polymer as a function of vapor activity and temperature were presented in a previous article. A second aspect in understanding solvent/polymer interactions is the kinetics of desorption. Characterization of the solvent devolatilization is an important aspect of the drying procedure to guide processing protocols to eliminate residual solvent in the final spandex products, especially for medical applications [E. Hicks, A. Ultee, and J. Drougas, Science, 147, 373 (1965); J. W. Boretos and W. S. Pierce, J. Biomed. Mater. Res., 2, 121 (1968); P. M. Knight and D. J. Lyman, J. Membr. Sci., 17, 245 (1984)]. This article reports data for desorption kinetics under nominally isothermal conditions to provide diffusion coefficients as a function of polymer phase concentration and temperature. Desorption curves were found to be Fickian at least up to the half‐time of desorption. Diffusion coefficients were therefore calculated using a half‐time method. Temperature effects upon sorption or desorption were measured to obtain corrected diffusion coefficients and found to be singificantly different than the apparent diffusion coefficient measured from a conventional McBain sorption cell. © 1994 John Wiley & Sons, Inc.
Microphase separation and crystallization of crystalline–amorphous type block copolymer. VI. Crystalline part in crystalline domain
Authors: Ishikawa Satoshi 
Published: April 2003

AbstractThe crystalline and amorphous areas in poly(tetrahydrofuran) (PTHF) domains in a poly(tetrahydrofuran‐b‐isoprene) (crystalline–amorphous, PTHF = 52 wt %) film were distinguished by transmission electron microscopy and the relation between the crystallization and domain shape was clarified. The ratio of PTHF domain containing amorphous area was low in the case of the fewer interfaces of the small curvature formed by poly(isoprene) domain. The PTHF crystallization was closely related to the interface shape. © 1994 John Wiley & Sons, Inc.
Recognition of substrates by membrane potential of immobilized glucose oxidase membranes
Authors: Higuchi Akon , Hara Mariko , Yun Kyu‐Sik , Tak Tae‐Moon 
Published: April 2003

AbstractThe shifts in membrane potential, caused by the injection of glucose into a permeation cell, were measured using immobilized (entrapped) glucose oxidase membranes. No, pH change in the permeation cell was observed upon injection of glucose, but the shift in membrane potential was definitely detected. The shift in membrane potential was observed under nitrogen bubbling (in the absence of oxygen) using initially used enzyme membranes. It was, therefore, suggested that the shifts in membrane potential were not caused by an enzyme‐substrate reaction, but by binding of the substrate to the enzyme, which indues a conformational change in the enzyme and leads to a change in charge density in the enzyme membrane. This mechanism is also supported by the fact that the shifts in membrane potential were observed upon injection of not only D‐glucose but also L‐glucose as reported in our previous study [J. Chem. Soc. Faraday Trans., 87, 695 (1991)]. © 1994 John Wiley & Sons, Inc.
Electron beam chemistry of polyvinylpyridinium salts
Authors: Lee Kang I. 
Published: April 2003

AbstractVarious polyvinylpyridinium salts have been studied under electron beam. The relationship between electron beam sensitivities and chemical structural variables of polyvinylpyridinium salts has been studied by conventional scanning electron microscopy. Several possible mechanisms of radiation‐induced solubility change in the polyvinylpyridine system have been discussed. © 1994 John Wiley & Sons, Inc.
Evaluation of a sorption equation for polymer–solvent systems
Authors: Vrentas J. S. , Vrentas C. M. 
Published: April 2003

AbstractThe predictive capabilities of a proposed sorption equation for describing the sorption behavior of glassy polymer–penetrant systems is evaluated. Factors determining the shapes of isotherms for glassy polymer–penetrant systems are considered. Data–theory comparisons are presented for three glassy polymer–penetrant systems. © 1994 John Wiley & Sons, Inc.
Determination of infinite dilution diffusion and activity coefficients of solvents in polystyrene by inverse gas chromatography on a capillary column
Authors: Bonifaci Luisa , Carnelli Lino , Cori Laura 
Published: April 2003

AbstractInfinite dilution activity and diffusion coefficients of several solvents in polystyrene have been measured by inverse gas chromatographic on a capillary column for temperatures between 110 and 170°C. Chromatographic data have been treated according to Khan's model, evaluating the contribution to the peak broadening due to radial and axial molecular diffusion in the mobile phase, radial diffusion in the stationary phase, and interfacial mass transfer resistance. Four capillary columns have been prepared with coating thickness ranging from 0.5 to 3.3 microns in order to determine the minimum thickness necessary to obtain reliable measurements of the diffusion coefficient of the solvent in the polymer in every possible experimental condition. Our experimental data are in considerable agreement with the data already available in the literature, obtained by static and chromatographic methods. © 1994 John Wiley & Sons, Inc.
Synthesis of graft polyethers by ring‐opening copolymerization of epoxy‐terminated poly(ethylene glycol) with epoxides
Authors: Ikeda Isao , Horie Naofumi , Suzuki Kimihiro 
Published: April 2003

AbstractThe copolymerization of epoxy‐terminated poly(ethylene glycol methyl ether) (CH3PEG–epoxide) with low molecular weight epoxides such as phenyl ether (PGE) was carried out to prepare the PEG graft polyethers. Potassium tert‐butoxide was the most favorable catalyst used to obtain the graft polyethers. The apparent number‐average molecular weight (Mn) of the graft polyethers decreased with increase in PGE concentration because PGE acted as both solvent and comonomer. The composition of the graft polyethers (PGE/CH3PGE), however, increased with increase in PGE concentration and was almost consistent with the feed ratio of the two monomers. The graft polyethers whose composition was over 10 were insoluble in water. The Mn of the graft polyethers was little affected by the reaction temperature, but more affected by the presence of solvent. Besides PGE, n‐butyl glycidyl ether and styrene oxide were effective as comonomers. CH3PEG–epoxide hardly polymerized in tert‐butyl alcohol. © 1994 John Wiley & Sons, Inc.
Soldering deterioration of epoxy‐molded IC packages after moisture absorption
Authors: Asai Shin'ichiro , Saruta Uki , Tobita Masanori 
Published: April 2003

AbstractMolding compounds for surface‐mount devices were studied by using various kinds of epoxy resins in a practical model compound with phenol resins as curing agents. The physical properties of the cured compounds were studied at 215°C to simulate the condition that they encounter during the soldering process that can relate to package cracks. The compounds that have low modulus at soldering temperature, low equilibrium water concentration, and good adhesion toward the die pad developed few cracks after soldering. The compounds from difunctional epoxy resins showed good durability, resisting this phenomenon. © 1994 John Wiley & Sons, Inc.
ESCA characterization of polyacrylonitrile‐based carbon fiber precursors during its stabilization process
Authors: Bhardwaj Ashish , Bhardwaj Ishwar Singh 
Published: April 2003

AbstractOxidation process control plays a key role in influencing the development of carbon fiber properties. The characterization of oxidized fibers is difficult because of their poor solubility in organic solvents and strong absorbance. X‐ray photoelectron spectroscopy (XPS) has been used in the surface characterization of carbon fiber precursors during the oxidation or stabilization process. The changes in surface elemental composition and functionalities of carbon and oxygen have been identified. Quantitative changes have been noticed in surface functional groups as the oxidation process proceeds. © 1994 John Wiley & Sons, Inc.
Synthesis and properties of polyamides and copolyamides based on 2,6‐naphthalene dicarboxylic acid
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei , Lin Yie‐Shin 
Published: April 2003

AbstractA number of polyamides based on 2,6‐naphthalene dicarboxylic acid (NDA) and various aromatic diamines were synthesized in N‐methyl pyrrolidone (NMP) containing lithium chloride (LiCl) or calcium chloride (CaCl2) by direct polycondensation using triphenyl phosphite and pyridine. The best reaction conditions for polycondensation were determined in terms of factors such as the amount of the solvency‐promoting reagent such as LiCl or CaCl2 and the initial reactant concentration. Thus, almost all polyamides were obtained with inherent viscosities above 1.0 and up to 3.28 dL/g. Similarly, high molecular weight copolyamides with inherent viscosities of 1.76–3.61 dL/g were prepared from 4,4′‐oxydianiline (ODA) and mixed dicarboxylic acids of NDA/terephthalic acid (TPA) or NDA/isophthalic acid (IPA). The solubility of NDA homopolyamides depended on the diamine components. The polyamides derived from meta‐, sulfone‐, or alkylene‐linked diamine showed increased solubility. Copolymerization of ODA with NDA/IPA led to a significant increase in solubility, whereas with NDA/TPA, it gave a limited improvement. All the homopolyamides and copolyamides showed an amorphous X‐ray diffraction pattern. Almost all the polymers soluble in aprotic solvents can be solution‐cast into strong and tough films. Glass transition shifts of some NDA polyamides can be observed in the differential scanning calorimetry (DSC) curves ranging from 243 to 345°C. Most NDA/IPA–ODA copolyamides also showed clear transitions in the range of 255–268°C. In nitrogen, all the polymers showed no significant weight loss up to 400°C, and their 10% weight loss temperatures were recorded in the range of 434–541°C. © 1994 John Wiley & Sons, Inc.
Monomer‐to‐water ratios as a tool in controlling emulsion copolymer composition: The methyl acrylate–indene system
Authors: Noël Lilian F. J. , Van Zon Jan M. A. M. , German Anton L. 
Published: April 2003

AbstractA drifting copolymer composition as a function of conversion is an aspect typical of copolymerization. Reducing this so‐called composition drift in batch copolymerizations will lead to a decrease in chemical heterogeneity of the copolymers formed. For monomer systems in which the more water‐soluble monomer is also the more reactive one, theory predicts that composition drift in emulsion copolymerization can be reduced or even minimized by optimizing the monomer‐to‐water ratio. The monomer combination methyl acrylate–indene (MA–Ind) meets the requirements needed to minimize composition drift in batch emulsion copolymerization. Therefore, this monomer combination is chosen as a model monomer system in order to verify this theoretical prediction. Reactivity ratios needed for model predictions have been determined by low conversion bulk polymerization, resulting in rMA = 0.92 ± 0.16 and rInd = 0.086 ± 0.025. Furthermore, emulsion copolymerization reactions at the same monomer mole fraction are performed at different monomer to water ratios. From the good agreement between experiments and theoretical predictions for MA–Ind, it was concluded that control and even minimization of composition drift in batch emulsion copolymerization for monomer systems in which the more water‐soluble monomer is also the more reactive one is indeed possible by changing the initial monomer‐to‐water ratio of the reaction mixture provided that the reactivity ratios of both monomers are not too far from unity. © 1994 John Wiley & Sons, Inc.
Number‐average molecular weight by size exclusion chromatography
Authors: Balke S. T. , Mourey T. H. , Harrison C. A. 
Published: April 2003

AbstractIt is now theoretically possible to obtain absolute accurate values of number‐average molecular weight of complex polymers (e.g., branched polymers or copolymers) using size exclusion chromatography (SEC) with only a detector that measures the difference between the eluting polymer solution viscosity and the viscosity of the pure mobile phase (a differential viscometer [DV] detector). However, both precision and accuracy of these “DV M̄n” values are of concern. In this work, the precision of NBS 706 polystyrene was found to be two to three times worse for the DV M̄n than for the conventionally calculated M̄n. Also, regarding accuracy, the DV M̄n values were affected by the location of the universal calibration curve along the retention volume axis (a problem intimately associated with the problem of specifying the correct interdetector volume), the sensitivity of the DV detector to low molecular weights present in the sample, and axial dispersion. Each of these sources of error are examined in turn and two methods of calculating M̄n values are proposed. © 1994 John Wiley & Sons, Inc.
A polymerizable photoredox initiation system for vinyl photopolymerization
Authors: Du Fu‐Sheng , Zhang Peng , Li Fu‐Mian 
Published: April 2003

AbstractA polymerizable photoredox system consisting of 4‐methacryl oxbenzophenone (MABP) and N,N‐dimethlaminoethyl methacrylate (DMAEMA) used for the photopolymerization of acrylonitrile (AN) was studied. It was found that the polymerization rate is proportional to the 0.93th power for the AN concentration, the 0.28th power for the MABP concentration, and the 0.25th power for the DMAEMA concentration. The overall activation energy of the polymerization obtained is 30.43 kJ/mol. The recorded ESR spectrum indicates that the excited‐state MABP abstraets hydrogen mainly from the methyl group of the dimethylamino moiety. The comparison of the initiation ability of polymeric MABP or polymeric DMAEMA with their monomeric forms has also been done and the results indicate that in good solvents P (MABP) has a much higher initiation ability than that of monomeric MABP, but monomeric DMAEMA and P (DMAEMA) display almost the same initiation ability. In poor solvent, the initiation ability of P (MABP) is not so obviously higher than that in good solvents. The result of UV analysis of P (AN) initiated by the MABP–DMAEMA system indicates that both MABP and DMAEMA not only initiate the photopolymerization of AN, but also enter into P (AN) polymer chains. © 1994 John Wiley & Sons, Inc.
Iron (III) chelating resins. V. Cross‐linked copolymers of 1‐(β‐acrylamidoethyl)‐3‐hydroxy‐2‐methyl‐4(1H)pyridinone (AHMP) and N,N‐dimethylacrylamide (DMAA) for iron (III) chelation studies
Authors: Feng Minhua , Van Der Does Leen , Bantjes Adriaan 
Published: April 2003

AbstractIron (III) chelating resins containing 3‐hydroxy‐2‐methyl‐4(1H)pyridinone (HMP) groups were prepared from 1‐(β‐acrylamidoethyl)‐3‐hydroxy‐2‐methyl‐4(1H)pyridinone (AHMP) and N,N‐dimethylacrylamide (DMAA), using N,N′‐ethylene‐bis‐acrylamide (EBAA) as a cross‐linking agent. The cross‐linked AHMP–DMAA copolymer resins were very stable and exhibited a high hydrophilicity with water contents of the swollen resins of 85–90%. The iron (III) chelating capacity of the resins was determined at physiological pH, and the chelating efficiency was, in general, higher than 90%. The iron (III) chelation was about 80% after 2 h and almost complete in 8 h. The distribution ratio of iron (III) between the resin and iron (III) solutions was quite high (3700–25,000 mL/g) and depended on the initial iron (III) concentration. It was possible to remove iron completely from aqueous solutions by using excess amounts of the resin. The resin also showed a very high selectivity for iron (III), and selectivity coefficients for iron (III) in the range of 9.6 × 108−1.4 × 1012 were determined at pH 5.6 in binary solutions of Fe3+ with Mg2+, Cu2+, Ca2+, Mn2+, and Zn2+. The iron (III) chelating resins could be easily regenerated and used again without any considerable loss of their iron (III) chelating capacities. © 1994 John Wiley & Sons, Inc.
Titration of aldehydes present in poly(ethylene terephthalate)
Authors: Villain Franck , Coudane Jean , Vert Michel 
Published: April 2003

AbstractAldehydes are known to be present in PET performs and PET bottles. However, the analysis of these aldehydes is difficult because of the high crystallinity of PET and because of its insolubility in common solvents. Titration of acetaldehyde was investigated comparatively by four different methods: by the solid/gas headspace technique (s/g HG), accepted industrially as the standard method, by colorimetry, based on complexation with pararosaniline dye, by colorimetry, based on derivatization as 2,4‐dinitrophenyhydrazones, and by headspace liquid/gas chromatography (1/g HS). Similar results were achieved by the last three methods. In contrast, the standard solid/gas headspace chromatography yielded data that was one order of magnitude smaller. The presence of formaldehyde in PET performs was detected by liquid/gas headspace Chromatography only. © 1994 John Wiley & Sons, Inc.
Analysis of the notch tip damage zone in biaxially oriented polypropylene
Authors: Snyder J. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe circular notch tip damage zone in biaxially oriented polypropylene has been analyzed using a thickness correction to the elastic stress distribution for a sharp‐notched tension specimen. The size and shape of the damage zone as a function of applied stress followed a critical mean stress criterion, independent of specimen thickness. Also, the damage zone only grew while σ3 was greater than zero. Close observations of sections through the damage zone revealed that the circular zone, which consisted of many delamination crazes, had a distinctive pattern when viewed across the thickness difection. Large crazes grew into a triangular pattern with smaller crazes in between them. The shape developement of the triangular profile as well as the smaller crazes was explained using a stress‐redistribution argument. The growth path of the delamination crazes in the x‐z plane appeared to be in a direction perpendicular to the direction of σ3. © 1994 John Wiley & Sons, Inc.
Blend structure of commingled plastic from recycled polyethylene and polystyrene
Authors: Li T. , Henry S. , Silverstein M. S. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe hierarchical morphology of commingled plastic waste in the form of thick beams prepared by the ET‐1 process has been examined. Blends of recycled high‐density polyethylene (RHDPE, New Jersey Curbside Tailings) with 25 and 35 wt % expanded polystyrene (EPS) were compared with blends of a virgin high‐denisty polyethylene resin (VHDPE). At the macroscale, observed with the optical microscope, the beams consisted of a solid skin that extended about one‐third of the distance to the center of the beam and a voided core with about half the density of the skin. The phase morphology of the skin at the microscale was characterized by examining etched cryogenic fracture surfaces in a scanning electron microscope. The blends of RHDPE and VHDPE exhibited a gradient morphology with highly elongated EPS domains near the edge and spherical or co‐continuous EPS domains closer to the core. The morphology gradient was created by the competition between the relaxation rate of the melt‐flow morphology and the cooling rate in the mod. In addition to high‐density polyethylene, a variety of other components were identified in RHDPE by photoacoustic infrared and thermal analysis. These included polypropylene, polystyrene, poly(ethylene terephthalate), and chunks of nonpolymeric material. As a result of the heterogeneous composition, the crystallinity of RHDPE was significantly lower than that of VHDPE. © 1994 John Wiley & Sons, Inc.
Electrical, thermal, and photo properties of poly(phenylene vinylene) precursors. II. Microwave‐induced elimination reactions in precursor polymer films
Authors: Torries‐Filsho Afranio , Lenz Robert W. 
Published: April 2003

AbstractMicrowave radiation (MWR) was used to induce the elimination reaction of the poly(phenylene vinylene)–polyelectrolyte precursors polymer (PPV precursor) into the fully conjugated polymer. The process was applied mainly to the unsubstituted PPV and was followed by infrared spectroscopy. The extent of the elimination process was also determined from the amount of residual sulfur in the film after the irradiation process. The microwave‐induced elimination process was also attempted using PPV precursor films that had been impregnated with anionic compounds containing iron. The molecular mechanisms for the observations are discussed and comparison with the elimination reaction induced by other energy sources is also made. © 1994 John Wiley & Sons, Inc.
The surface modification of polyethylene by solution‐phase photochemical grafting using short irradiation times
Authors: Hamilton L. M. , Green A. , Edge S. , Badyal J. P. S. , Feast W. J. , Pacynko W. F. 
Published: April 2003

AbstractThe surface modification of low‐density polyethylene by solution‐phase photochemical grafting with acrylic acid and acrylamide is described. After irradiation for 3 min, the contact angles of the modified surfaces with water were ca. 20, 30, and 40°C and ca. 40, 40, and 80°C for grafting solutions containing 2M, 1M, and 0.1M of acrylamide and acrylic acid respectively. X‐Ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATRIR) of the modified polyethylene surfaces were consistent with the presence of grafts of polyacrylamide or poly(acrylic acid). Grafting using low concentrations of monomers, that is, 0.1M, resulted in a small, 20° decrease in contact angle for grafting with acrylic acid but a larger, 60°C decrease for acrylamide. © 1994 John Wiley & Sons, Inc.