bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural changes in polyethylene films at small deformations
Authors: Lipatov Yu. S. , Moisya E. G. , Logvinenko P. N. , Mengeres G. Ya. 
Published: April 2003

AbstractStructural changes in PE films at deformation 2–7% under constant load were studied by molecular probe method. It was shown that at these conditions some structural rearrangements take place which involves more than 20% of polymer volume, only 2–3% being transformed in the state of three‐dimensional ordering. The most part of ordering observed was connected with two‐dimensional ordering in the AC plane of molecular folding, involving tie chains near the crystallites. The effect of relaxation process during deformation on structural rearrangements in PE films was also investigated.
Kinetics of wet oxidation of nylon 66
Authors: Sundstrom D. W. , Luciano A. J. , Klei H. E. 
Published: April 2003

AbstractThe kinetics of the aqueous phase oxidation of nylon 66 was studied at temperatures up to 190°C. The nylon 66, in the form of a cylindrical disc, was attached to the shaft of a variable‐speed drive inside the reactor. With a rotating disc geometry, the chemical kinetics of the surface reaction can be separated from the mass transfer effects. By measuring the reaction rates at different temperatures, pressures, and disc rotational speeds, a kinetic rate expression was developed relating nylon degradation to dissolved oxygen concentration and temperature. The order of reaction with respect to dissolved oxygen concentration was 0.6, and the activation energy was 42 kcal/g‐mole.
Effect of molecular structure of phenolic resin on solder dip resistance and peel strength of printed circuit adhesives
Authors: Namiki Isamu 
Published: April 2003

AbstractPhenolic resins were synthesized by using various kinds and amounts of catalyst and changing the mole ration of formaldehyde and phenol. The solder dip resistance and the peel strength were measured for two‐component printed circuit adhesives mixed with poly(vinyl acetal) resin, and the relation between these properties and the molecular structure of the phenolic resins were studied. Catalysts such as ammonia, amines having low boiling points, and alkaline earth metal oxide and hydroxides give resins with good properties. When the mole ratios of ammonia to phenol and formaldehyde to phenol are respectively 0.05–0.10 and 1.5, the resins obtained have good characteristics. The solder dip resistance is improved by aging the resin solution at moderate temperature.
Rheological properties of partially hydrolyzed ethylene–vinyl acetate copolymers
Authors: Jacovic Mihailo , Yamada Muneki , Macknight William J. , Porter Roger S. 
Published: April 2003

AbstractStudies have been made of steady‐shear and dynamic viscosities for melts of two ethylene–vinyl acetate copolymers and their partially hydrolyzed derivatives using a Weissenberg rheogoniometer over the temperature range of 123–150°C with some tests at 160°C. The flow activation energy of all samples studied was essentially independent of shear stress. The introduction of hydroxyl groups in controlled concentrations, however, produced a complicated flow behavior. At low concentrations, there is a marked increase in Newtonian viscosity, flow activation energy, and shear dependence of viscosity. In contrast to previous reports, a further increase in all three functions was not observed with increasing vinyl alcohol concentration. Dynamic viscosities, in contrast, show monotonic increases with increasing hydroxyl group content, as do activation energies derived from the temperature dependence of the dynamic viscosity. These data may result from an increased chain cohesion due to hydrogen bonding of hydroxyl groups.
Analyse par résonance magnétique nucléaire des polycondensats urée–formol
Authors: Duclairoir Christian , Brial Jean‐Claude 
Published: April 2003

AbstractThe oligomer reaction products between urea and formaldehyde were preliminarily studied by 60‐MHz NMR spectroscopy. This analytical method was extended to urea–formaldehyde copolymers and provided means to attempt to determine their molecular stucture. Prior to NMR analysis, dilution water was removed by freeze drying in order to avoid degradation and advancement of the resin. Lithium chloride was found to enhance polycondensate solubility in deuterated dimethylsulfoxide and to improve resolution of the spectra by reducing overlapping of the signals. It was then possible to proceed to a qualitative and quantitative analysis of urea–formaldehyde copolymer structure. Structural differences appeared between one‐step synthesized resins and those involving a second urea addition; in the latter case, the percentage of unreacted urea was calculated. The shape of the unresolved broad signal assigned to the various methylene groups yielded further information on the resins. A particular shoulder on the methylene signal gives evidence for polyoxymethylene sequences occurring in polycondensates synthesized from concentrated aqueous formaldehyde solutions.
Photo‐induced graft copolymerization of methyl methacrylate on oxidized poly(vinyl alcohol) fiber
Authors: Ogiwara Yoshitaka , Yasunaga Toshio , Kubota Hitoshi 
Published: April 2003

AbstractPhoto‐induced graft copolymerization of methyl methacrylate on oxidized poly(vinyl alcohol) fiber was investigated. Oxidation of the fiber sample with sodium hypochlorite or periodic acid led the radical formation by photo‐irradiation to intensify markedly. ESR spectra of the irradiated oxidized sample proved that a considerable amount of triplet component radical was contained in it, whereas the unoxidized sample mostly indicated a singlet. The spectra found in the irradiated unoxidized sample was assigned to two radicals, I and II, and for the oxidized sample, to III and IV. The spectrum for I must be a singlet, and a triplet for II, III, and IV. Among the last three, II was less stable toward heat. As the oxidized sample has a high activity for photoinitiation, the radicals of III and IV are presumed to be the sites of graft copolymerization:
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Polymer composites containing plasma‐treated mica. I. Flow and mechanical properties
Authors: Schreiber H. P. , Tewari Y. B. , Wertheimer M. R. 
Published: April 2003

AbstractSuzorite mica has been surface modified by microwave plasma treatment in ethylene gas. The surface‐treated mica was used as a filler in polyethylene, polystyrene, and a mixture of these two polymers. Significant changes in rheological behavior ensue. These indicate that adhesion between polyethylene and irradiated mica is superior to that of interfaces using unirradiated mica. In contrast, ethylene irradiation reduces the ability of filled polystyrene compounds to store elastic energy in melt flow, an effect consistent with impaired adhesion at interfaces involving these components. An intermediate situation exists in the case of the two‐polymer blend. The tensile properties of these systems also reflect surface treatment, reinforcement occurring in polyethylene‐containing compounds, while the tensile properties of polystyrene composites deteriorate. Plasma‐induced surface modifications of fillers to produce desired property changes in specified polymer matrixes are implied by the present work, but a fuller understanding of the chemistry of surface modification reactions is needed to substantiate these implications.
Preparation of macroreticular anion exchange membrane and its behavior relating to organic fouling
Authors: Kusumoto Koshi , Ihara Hirofumi , Mizutani Yukio 
Published: April 2003

AbstractBase membranes were prepared by coating a monomer mixture consisting of styrene–divinylbenzene–polybutadiene–t‐amyl alcohol onto a polypropyrene cloth and subsequently by polymerizing the monomers. The resultant base membranes were chloromethylated and then quaternized. Thus, macroreticular anion exchange membranes were prepared and their properties were investigated. Furthermore, the organic fouling of the membranes was studied by using Na dodecylbenzenesulfonate as a foulant. The resistibility of the membranes was dependent on the balance between the porosity of the membranes and the foulant quantity.
Effect of the hydrophilic nature of growing radicals on the formation of particles in the preparation of soap‐free carboxylated polystyrene latexes
Authors: Sakota Kazuyuki , Okaya Takuji 
Published: April 2003

AbstractSoap‐free carboxylated polystyrene latexes have been prepared by copolymerizing acrylic acid (AA) in a wide range of degree of neutralization using a slight amount of soap, and the particle formation process was investigated from the number and uniformity of particles. It was found that the degree of neutralization of AA as well as the amount of AA have a great effect on the formation of particles. On the basis of the calculation results of the composition of the growing radical formed in the aqueous phase at the initial stage of the polymerization, the results can reasonable be explained by a change in the hydrophilic nature of growing radicals formed in the aqueous phase at the initial stage of the polymerization, the results can reasonably be explained by a change in the hydrophilic nature of growing radicals which are formed in the aqueous phase and precipitate out to form particles. It was also established that the introduction of α‐methylstyrene or methyl methacrylate has a great effect on the formation of particles, which is consistent with the above‐described considerations.
Isocyanate resins from amide copolymers
Authors: Wright H. J. , Harwell K. E. 
Published: April 2003

AbstractUseful isocyanate‐containing polymers may be made by reacting amide copolymers with a hypochlorite such as sodium hypochlorite. A highly branched carbon structure adjacent to the amide is required, otherwise the isocyanate is lost through reaction with components of the reaction mixture. The polymeric isocyanates react rapidly with monomeric and polyamines and at adequate rates with hydroxyl compounds. These polymers are very useful in paint films and other applications due to their ability to undergo crosslinking and chain extensions by reaction of the isocyanate groups.
Internal friction in polymer‐impregnated hardened cement paste
Authors: Whiting D. , Kline D. E. 
Published: April 2003

AbstractHardened cement paste (HCP) specimens were prepared with hydration times of 1, 3, 7, 28, and 180 days. Specimens were oven dried and subsequently impregnated with methyl methacrylate, tert‐butylstyrene, polyethylene glycol, and an epoxy resin system via a vacuum–pressure technique. Internal friction (Q−1) of in situ polymerized specimens was measured over the temperature range from 100° to 500°K. Results indicate that the internal friction spectra of polymer‐impregnated specimens closely parallels the internal friction spectra of the bulk polymers used for impregnation. Magnitudes of the internal friction peaks in the impregnated specimens were found to be less than that expected on the basis of volume fraction of polymer present. These results are attributed to hindered motion at the cement/polymer interface.
Structure of decrystallized cotton in fabrics prepared by alkali and acrylonitrile treatments
Authors: Hirai Asako , Tsuji Waichiro , Kitamaru Ryozo , Hosono Masao 
Published: April 2003

AbstractThe crystalline structure of decrystallized cotton, prepared by partial cyanoethylation with the use of sodium hydroxide aqueous solution and acrylonitrile, was examined by x‐ray and IR data, in connection with such fabric properties as moisture regain. It was found that the moisture regain of the cotton fabric first increased, passed through a maximum at about 6 mole‐% of cyanoethylation, and then slightly decreased with increasing degree of cyanoethylation. The increase of moisture regain in the region of the lower degree of cyanoethylation was well related to the decrease in the crystallinity of cotton. The x‐ray diffraction studies revealed that the distension and disorder of the unit cell occurred primarily in the direction perpendicular to the (101) crystal plane as cyanoethylation proceeded.
Gel formation in polymers undergoing radiation‐induced crosslinking and scission
Authors: Handlos V. N. , Singer K. A. 
Published: April 2003

AbstractA study was made of the solubility of irradiated polyethylene. The experimental data were treated according to the Saito‐Inokuti theory for gel formation in polymers exposed to ionizing radiation. Among other things, this theory is based upon the molecular weight distribution of the unirradiated polymer; in the present work, the actual distributions were determined by high‐temperature gel permeation chromatography and corrected for long‐chain branching. Under these circumstances, good agreement between theory and experimental data was obtained, which allowed the determination of the radiation yield of main‐chain scission and crosslinking.
Water‐soluble polymers as retention aids in a model papermaking system. III. Modified polyacrylamides
Authors: Howard G. J. , Hudson F. Lyth , West Jeremy 
Published: April 2003

AbstractThe pigment retention efficiency, in a model papermaking system, of anionically and cationically modified polyacrylamides was compared to that of the unmodified homopolymer. The anionic polyacrylamide is a much less efficient retention aid, especially at high pH's; the nonionic and cationic polymers perform similarly and without any marked pH dependence. However, it is the nonionic and anionic polyacrylamides which are similarly poor at fiber flocculation, at pH's between 4.5 and 7.5, whereas the cationic polymer is a good fiber flocculant. All three polymers stabilize pigment suspensions. The anionic polymer is not effective in heteroflocculation of mixed dispersions of fibers and pigment, whereas both the nonionic and cationic are good flocculants, the latter being less susceptible to overdosing. Equilibrium adsorption isotherms were determined; the cationic polymers is, unlike the other modified polyacrylamide, very well adsorbed by cellulose fibers. Onto titanium dioxide, polymers adsorbed in the order anionic < nonionic < cationic. A further differentiation of the cationic polymer is that it gives high pigment retention in sheet formation without markedly increasing the resistance to fluid flow through the forming sheet. Although a process of heteroflocculation is postulated for both nonionic and cationic polymers, in the former case it is thought that the primary adsorption is onto titanium dioxide, whereas with the latter it is onto cellulose.
The kinetics of the trimethoxyboroxine‐induced thermal polymerization of phenyl glycidyl ether
Authors: Lopata Eugene S. , Riccitiello Salvatore R. 
Published: April 2003

AbstractThe kinetics of the bulk thermal polymerization of phenyl glycidyl ether induced by trimethoxyboroxine were investigated. Infrared absorption spectroscopy and gel permeation chromatography were used to follow the course of polymerization, while proton and boron‐11 NMR spectroscopy were used to support the kinetic model developed. The postulated mechanism involves a fast‐initiated, nonstationary cationic polymerization with five elementary steps, including spontaneous and monomer transfer as well as a termination reaction. The trimethoxyboroxine was found to be incorporated into the structure of the cured polymer. The polymerization was followed at several temperatures and with several ratios of initial concentrations of trimethoxyboroxine to phenyl glycidyl ether.
Transitions in phenolic polymer
Authors: Warfield R. W. , Lee G. F. 
Published: April 2003

AbstractThe solid‐state properties of a highly crosslinked amorphous resole‐type phenolic polymer have been studied by compressibility and torsional braid analysis measurements. Three secondary transitions were found over the temperature range of 123° to 623° K the largest of which occurs at about 393°K. These results confirm previously made electrical resistivity and specific heat measurements. These transitions are discussed in relation to the structure of this polymer.
Low‐frequency thermomechanical spectrometry of polymeric materials: Tactic poly(methyl methacrylates)
Authors: Gillham J. K. , Stadnicki S. J. , Hazony Y. 
Published: April 2003

AbstractA computerized and automated torsional pendulum has been used to characterize amorphous poly(methyl methacrylates) at about 1 Hz in the temperature sequence 473° → 93° → 473°K. The effects of thermal prehistory, temperature cycling, water content, and tacticity are demonstrated. In particular, a comparison of the out‐of‐phase shear modulus (G″) versus temperature for “syndiotactic,” “atactic,” and “isotactic” polymer specimens shows that the intensity of the glassy‐state β loss peak decreases with increasing isotactic content while the temperature of its location remains the same. Extrapolation suggests that completely isotactic polymer would not display a β loss peak. The shape and location of the G″ data at low temperatures indicate that the basic mechanism of the β process is the same for the three polymer samples and support the validity of the extrapolation. The effect of tacticity is reflected also in the glass transition region; the isotactic sample has its Tg about 65°C lower with greater intensity than the syndiotactic polymer.
Peroxide crosslinking of ethylene–vinyl acetate copolymer
Authors: Narkis M. , Miltz J. 
Published: April 2003

AbstractThe work reported here concerns the peroxide crosslinking of ethylene–vinyl acetate rubber. Calculated values for scission‐to‐crosslinking ratios are higher for EVA than for low‐density polyethylene. In the temperature range from 150 to 200°C at a constant peroxide content, a rise in temperature results in a decrease in the obtained gel content. Some tensile and modulus–temperature results on crosslinked EVA samples are also reported on.
Iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal. IV. Fractional dissolution of copolymer
Authors: Ishigaki Isao , Morishita Norio , Morita Yosuke , Ito Akihiko 
Published: April 2003

AbstractA fractional dissolution on the oxymethylene copolymer obtained by the iodine‐initiated, solid‐state copolymerization of the tetraoxane–1,3‐dioxolane‐methylal system has been carried out using a mixed solvent which consists of tetrachloroethane, phenol, and cyclohexanol. On the fractional dissolution, the oxymethylene copolymer was divided mainly into two parts: one was the copolymer containing a larger amount of ethylene oxide unit in its main chain and having lower molecular weight; the other was copolymer containing a smaller amount of ethylene oxide unit and having a higher molecular weight. It was reasonably concluded that in this copolymerization system, the reaction proceeds from the surface to the center of the tetraoxane crystal to give a divided copolymer due to the heterogeneous properties such as copolymer composition and molecular weight.
Permeation properties of glycol chitosan–mucopolysaccharide complex membranes
Authors: Nakajima Akio , Shinoda Katsuro 
Published: April 2003

AbstractThe permeation properties of glycol chitosan–chondroitin sulfate C and glycol chitosan–heparin complex membranes have been studied. Discussion is devoted primarily to the desalination properties in reverse osmosis. Salt rejection and flux were dependent both on the composition of the membranes and the pH of the feed solutions. The results indicate that these complexes behave like polyampholytes. Minimum salt rejection occurs around the isoelectric point. Another characteristic of these membranes is a large pressure dependence of the salt rejection. This could be interpreted by assuming the compaction of these highly swollen membranes at high pressure.
Effect of water on permeation, diffusion, and solution of gases in cellophane
Authors: Kamiya Yoshinori , Takahashi Fumio 
Published: April 2003

AbstractThe laminate method for studying the permeability and diffusivity of moistened cellophane to gases is described and the humidity dependence of the transport parameters for H2, He, and Ne is presented. In the relative humidity region of about 0% to 60%, a small increase in the permeability was observed, which is caused by a comparatively small increase in the diffusivity owing to the plasticizing effect of sorbed water and a decrease in the solubility. On the other hand, an extremely large increase in the permeability observed in the relative humidity region above 60% is mainly based on the diffusion coefficient of gas enhanced by the swelling effect of sorbed water. The presence of a minimum in the solubility–relative humidity curves has been confirmed and is discussed.
Grafting of nylon 66 with methyl methacrylate using dimethylaniline–benzyl chloride–acetic acid initiating system
Authors: Hebeish A. , El‐Rafie M. H. , Khalil M. I. , Bendak A. 
Published: April 2003

AbstractGrafting of nylon 66 with methyl methacrylate (MMA) under the initiating influence of dimethylaniline (DMA)–benzyl chloride (BC)–acetic acid (AC) mixture was studied to discover optimal conditions for grafting. Results of this investigation showed that a mixture of water/ethanol at a ratio of 90:10 constitutes the most favorable medium for the grafting reaction. Optimal grafting occurred when a concentration of 0.16 mole/l. DMA plus 0.17 mole/l. BC plus 0.2 mole/l. AC was used. Using lower or higher concentrations of this initiator led to lower grafting. On the other hand, increasing MMA concentration brings about a significant increase in the graft yield. The same holds true for reaction time and temperature, though an induction period was observed at a lower temperature (65°C) and when lower monomer concentration (2%) was used.
Flex‐resistant permeable PVC films
Authors: Otterstedt Jan‐Erik A. 
Published: April 2003

AbstractMicroporous poly(vinyl chloride) films with flex resistance in excess of 400,000 flexes at 20°C and 65% R.H. and in excess of 30,000 flexes at −;15°C, and water vapor permeability in excess of 250 g/m2 24 hr have been prepared from controlled expansion and curing of plastisols, which contain a poly(vinyl chloride) (PVC) resin with a K value of 75 or more and a plasticizer with a solubilizing power not greater than that of dioctyl phthalate. Controlled curing produces uniformity in the morphology of the cell walls while maintaining sufficiently high melt viscosity to retain the open structure of the porous material.
Rupture mechanisms of elastomer–metal adhesive systems
Authors: Schultz J. , Westbrook N. J. 
Published: April 2003

AbstractThis paper studies the influence of adverse conditions of stress and environment on a conventional industrial two‐coat adhesive system for bonding filled elastomers to steel. Several test methods were used in order to produce rupture at the elastomer/adhesive interface, but even the most stringent stress distributions produced rupture in the elastomer under relatively rapid constant strain rate testing conditions. However, under fixed strains termed“static fatigue” below immediate rupture conditions, fracture occurred cohesively in the adhesive. This fracture originated in the elastomeric phase of the adhesive. Comparison of elastomer and adhesive creep curves show that the locus of failure depends only upon the ultimate properties of the phase in which fracture occurs. This becomes more complicated for propagation of the fracture because of the influence of rheological, thermodynamic, and morphologic aspects of the other constituents of the assembly. A third type of rupture, produced at the metal surface, was observed by testing under corrosive conditions such as saline solution. Throughout the study, original observations are confirmed for systems using different elastomers, adhesives, or metal surface coatings.