bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonterminal unsaturated silane coupling agents for mineral‐filled ethylene–propylene rubber
Authors: Vondráček Petr , Čapka Martin , Schätz Miroslav 
Published: April 2003

AbstractThis paper describes the results of an experimental investigation concerning the effect of reactive organofunctional unsaturated silanes on mechanical properties of mineral‐filled ethylene–propylene elastomers. The tested group of the unsaturated silanes was prepared by hydrosilylation syntheses. The experimental silanes, 2,6‐octadienyltriethoxysilane, cis‐2‐butenyltriethoxysilane, 2‐(3‐cyclohexenylethyl)triethoxysilane, and 2‐(3‐cyclohexenylethyl)methyldiethoxysilane, led to a considerable improvement in mechanical and electrical properties of mineral‐filled vulcanizates based on peroxide‐cured ethylene–propylene elastomers. From the tested silanes, the 3‐cyclohexenylethylsilanes impart an improvement comparable with the action of vinyltris(2‐methoxyethoxy)silane, presently used as a standard coupling agent in mineral‐filled peroxide‐cured elastomers.
Irradiation of poly(vinyl chloride) with H2 plasma. I
Authors: Zahran A. H. , Nofal E. , Elsabee M. Z. , El‐Azmirly M. A. 
Published: April 2003

AbstractA system has been designed to serve as a plasma source and has the advantage of producing plasma of known energy and controlled intensity. Poly(vinyl chloride) films were irradiated with hydrogen plasma for different intervals of time. The effect of irradiation time and storing on the extent of crosslinking was investigated. The viscosity of the soluble part decreased at the initial stage of irradiation, then increased. The crosslinking extent was observed by measuring the swelling ratio of the irradiated samples. Spectral analysis indicated the formation of carbonyl groups and polyene structure in the irradiated PVC. The mechanisms of dehydrochlorination and crosslinking are discussed.
Some surface properties of plasma polymers prepared from hexamethyldisilazane and diethylaminotrimethylsilane
Authors: Hirotsu Toshihiro 
Published: April 2003

AbstractPlasma polymers from some silyl amines were produced by the radio frequency of 13.56 MHz, and the surface properties were investigated. The polymers were revealed to be as hydrophobic as a plasma polymer from tetramethylsilane, which does not contain nitrogen. The hydrophobicity became effective at around 50 Å thicknesses of these polymer layers deposited on micro‐slide glass. These polymers have gradually become comparatively hydrophilic with the aging. The change of wettability is probably due to the oxidation of these surface layers to form oxides and peroxides, which are more hydrophilic. The hydrophobic character of silyl amine plasma polymers could be explained by the lack of amines and/or amides in these polymers, as observed with ATR‐IR and ESCA spectra. These spectroscopic observations also suggest that nitrogen is a more fragile element in plasma than carbon or silicon in the silyl amines.
Functional silane‐modified calcium carbonate
Authors: Nakatsuka Takuo , Kawasaki Hitoshi , Itadani Katsuhiko , Yamashita Shinzo 
Published: April 2003

AbstractIn the course of graft polymerization of styrene on a calcium carbonate powder surface treated with a silance coupling agent such as γ‐methacryloxypropyltrimethoxysilane, gelation of the reaction mixture was observed just as on silane‐modified clay. Infrared spectroscopic and gel‐permeation chromatographic studies have revealed that the extracts of styrene monomer from the powder surfaces contained polymeric silane coupling agent, having crosslinking ability, besides monomeric silane coupling agent. The catalytic effect on the condensation of the silane coupling agent on the powder surface was found to be increased in following order: CaCO3 < P‐CaCO3 < clay, where P‐CaCO3 is a calcium carbonate modified with phosphoric acid. The order was parallel to the gelation tendency and to the acidity order (H0 ⩽ 6.8) on the surfaces. Direct evidence for bonding between the silane coupling agent and the phosphate moiety on calcium carbonate was not available; however, the silane‐modified P‐CaCO3 filler exhibited more reinforcing effects in peroxide‐cured ethylene–propylene–diene rubber (EPDM) and in sulfur‐cured styrene–butadiene rubber (SBR) than the silane‐modified calcium carbonate. These reinforcing effects are also discussed in relation to the molecular weight distribution of the silane coupling agent extracted.
Rheology and water swelling of carboxymethyl starch gels
Authors: Taylor N. W. 
Published: April 2003

AbstractA series of gels differing in ionic content was prepared by derivatizing starch with varying amounts of carboxymethyl add‐on. Some derivatives were lightly crosslinked with epichlorohydrin to reduce soluble material and increase the amount of gel. The gel fraction of each batch was isolated, and viscosity η, shear modulus G, and swelling in water and salt solution were then determined. One gel suspension, examined in more detail, was demonstrated to behave as a closely packed gel thickening agent, thereby warranting use of the three reduced functions: reduced concentration cQ (c is weight concentration of polymer, Q is swelling capacity in excess fluid), η/cQ, and G/c1/3. At cQ greater than about 2, η/cQ, and G/c1/3 reach constant plateau values, as is typical of other examples of closely packed gel thickeners. In a comparison among the gel suspensions, plateau values of the reduced viscosity function were nearly proportional to the apparent crosslink density G/c1/3, in agreement with other closely packed gel thickeners, but were not affected by ionic content of dry polymer. The water swelling capacities of the different gels ranged from 47 to 150 g/g and were correlated with both ionic contents and apparent crosslink densities, but the effects of these variables were less than suggested by theory.
Statistical analysis of nitrogen‐containing vinyl copolymers: Radiation‐induced copolymerization of vinyl acetate and N‐vinyl‐2‐pyrrolidone
Authors: Peppas Nikolaos A. , Gehr Todd W. B. 
Published: April 2003

AbstractRadiation‐induced copolymerization of vinyl acetate and N‐vinyl‐2‐pyrrolidone was carried out at 5°C using γ‐irradiation of 1450 rads/min. Copolymers prepared at conversions lower than 5% were analyzed by a saponification technique. Various linear and nonlinear statistical analysis techniques were used to determine the reactivity ratios of this system as r1 = 0.348 and r2 = 3.108. These data were examined and analyzed in relation to problems of elemental analysis involving nitrogen‐containing copolymers and to discrepancies in the reactivity ratios obtained by previous investigators. The presence of oxygen and a higher dose rate did not affect the copolymer composition within statistical error. Hydrolyzed copolymers prepared by this method have potential applications as biocompatible materials.
Synthesis of thermosetting polymers from the by‐products of coal conversion processes
Authors: Giori C. , Eisenberg W. , Yamauchi T. , Shelfo S. , Solomon I. 
Published: April 2003

AbstractThe use of coal conversion by‐products as raw materials in the synthesis of thermosetting polyesters has been investigated. Heavy tar residues were oxidized by gaseous oxygen in an alkaline medium, yielding a complex mixture of benzenecarboxylic acids and smaller amounts of aliphatic carboxylic acids. The mixture was polymerized by condensation with tetraethylene glycol “bottoms,” a by‐product of the synthesis of ethylene glycol. The resultant polyesters were cured by reacting them with epoxy resins in the presence of basic catalysts. Molded sheets and laminates were fabricated and tested. Tensile strength was found to increase with increasing curing time and with increasing concentration of epoxy crosslinking agent. Glass‐reinforced composites fabricated by the autoclave process showed an increase in flexural and shear strength with decreasing autoclave pressure.
On the thickness and spatial distribution of a fluoropolymer film deposited by solution dipping
Authors: Tompkins H. G. , Sharma S. P. 
Published: April 2003

AbstractPoly‐1H,1H‐pentadecafuorooctyl methacrylate is a barrier compound used to prevent silicone oil from creeping to relay contacts. It is essentially a methyl methacrylate polymer with a fluorocarbon side chain substituted for one of the methyl hydrogens. It is applied by dipping the part into a solution, with Freon TF as the solvent and the fluorocarbon polymer as the solute. This work considers the spatial distribution of the resulting film of barrier compound when it is deposited in this manner. The specific variables considered are concentration and withdrawal velocity. The samples were withdrawn from the solution with velocity perpendicular to the surface, and we show that the macrosopic uniformity and thickness of the film is dependent on this velocity. There exists a critical velocity (dependent on concentration) above which the film is nonuniform and below which the film is macroscopically uniform. Below the critical velocity, the thickness varies with velocity with approximately a v2/3 dependence. The critical velocity is about 13 mm/sec for a concentration of 0.2%. For macroscopically uniform films, a microscopic nonunitormity exists with a coverage of about 1/4 for an average film thickness of 90 Å.
Graft copolymerization of vinyl monomers onto modified cottons. XII. Grafting of 1,1‐dihydroperfluoroheptyl acrylate onto cellulose carbamate using hydrogen peroxide as initiator
Authors: Hebeish A. , El Alfy E. A. , Waly A. , Abou‐Zeid N. Y. 
Published: April 2003

AbstractCellulose carbamate having 1.4% N was grafted with 1,1‐dihydroperfluoroheptyl acrylate (DHPFHA) using H2O2 as initiator under a variety of conditions. The technique used involved padding the fabric in H2O2 solution at room temperature followed by impregnating it in an aqueous emulsion of DHPFHA. The graft yield, expressed as fluorine percent, was found to depend upon monomer and initiator concentration, temperature, and reaction time and pH of the polymerization medium as well as upon the carbamate content of the modified cotton. Increasing the monomer concentration up to 5% caused a considerable enhancement in grafting. The same holds true for initiator concentration up to a certain limit after which the grafting decreases. Raising the reaction temperature up to 100°C was accompanied by an increment in the magnitude of grafting reaction. The latter was characterized by an initial fast rate followed by a slower rate. Slightly acidic media (pH 5–6) proved to be the best for performing grafting. The graft yields were quite poor when grafting was carried out in acidic (pH 2–4) or alkaline (pH 8–12) media. The presence of a relatively smaller amount of carbamate groups in the cellulose molecules decreases its susceptibility to grafting. The opposite holds true for larger amounts. Incorporation of FeSO4 at low concentration in the monomer emulsion had no effect on the graft yield. However, the latter decreases at higher FeSO4 concentration. Grafted cellulose carbamate having ca. 15% fluorine showed very good oil and water repellency. The grafted product retained ca. 85% of the strength of cellulose carbamate.
Grafting onto wool. VII. Ceric ion‐initiated graft copolymerization of vinyl monomers. Comparison of monomer reactivities
Authors: Misra B. N. , Mehta Inderjeet K. , Dogra Ramesh 
Published: April 2003

AbstractIn an attempt to compare relative reactivities of vinyl monomers toward grafting, methyl methacrylate (MMA) and acrylic acid (AAc) were grafted separately to Himachali wool in aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Nitric acid was found to catalyze the reaction. Percent grafting was determined as a function of concentration of nitric acid, concentration of CAN, concentration of monomer, time, and temperature. Optimum conditions for maximum grafting were evaluated for each monomer and were found to depend upon the nature of the monomer. Reactivities of MMA and AAc toward grafting were compared with those of methyl acrylate (MA), ethyl acrylate (EA), and vinyl acetate (VAc) reported earlier from this laboratory and were found to follow the order MA > EA > MMA > VAc > AAc. An explanation for the observed order of reactivity of different vinyl monomers is presented.
Synthesis and characterization of rare earth metal‐containing polymers. I. Fluorescent properties of ionomers containing Dy3+, Er3+, Eu3+, and Sm3+
Authors: Banks E. , Okamoto Y. , Ueba Y. 
Published: April 2003

AbstractRare earth metal (Dy3+, Er3+, Eu3+, and Sm3+) salts of copolymers of methyl methacrylate–methacrylic acid, styrene–acrylic acid, 1‐vinylnaphthalene–acrylic acid and 1‐vinylanthracene–styrene–acrylic acid were prepared. The fluorescence of these polymer salts under ultraviolet excitation was investigated. The fluorescent intensity of polymer–Eu3+ films varied with film thickness because of incomplete absorption of exciting light, hence most of the measurements were made on pressed fine powders. The fluorescent intensity of mixed samples of Eu(III) acetate in a polymer matrix increased linearly with Eu content. However, the Eu3+–polymer complex system displayed typical concentration‐quenching behavior, reaching a maximum at 4–5 wt % Eu and decreasing with further increases in Eu content. This suggests that the ionomer contains ionic aggregates, in agreement with a recently proposed model. Such aggregates would create locally high Eu ion concentrations, whose interactions lead to concentration quenching at low nominal concentrations. The fluorescent intensity of the acrylic copolymers decrassed in the order methacrylate > styrene > naphthalene > anthracene. This sequence is explained by incrasing competition for the exciting light by the aromatic groups with negligible energy transfer from the aromatic groups to the Eu3+ ions. This is also consistent with the hypothesis that the ionic regions of the polymer are segregated.
Effect of photodegradation on dynamic mechanical properties of nylon 6
Authors: Yano Shoichiro , Murayama Mikio 
Published: April 2003

AbstractChanges in the dynamic mechanical properties of nylon 6 (α‐form) under ultraviolet light irradiation were investigated. On irradiation with spectrally dispersed ultraviolet light in the wavelength range of 219–415nm, the dynamic modulus E′ and the density of nylon 6 were increased below about 300nm. It was found that the increment in E′ and the density were the result of crosslinking. When E′ was measured with time elapsed during irradiation by light of 253.7 nm, E′ initially decreased with time, increased at a longer time, and then reached a limiting value asymptotically. From the result of the change in E′ with time, it was assumed that the scission and crosslinking reactions occur simultaneously during ultraviolet light irradiation. Thus, the change in E′ with elapsed time was exppressed by the equation E′t = E′0 exp (−k1t) + E′∞[1 − exp (−k2t)], where E′t is the dynamic modulus at time t, E′0 is the E′ at t = 0, E′∞ is the limiting value of E′, and k1 and k2 are the rate constants. The apparent activation energies for k1 and k2 were 3.23 and 2.50 kcal/mole, respectively, and the former value agreed with the activation energy for the scission of the amide groups. The effects of the photodegradation on the temperature dispersion of nylon 6 were also investigated. On irradiation with light at 253.7 nm, the α‐relaxation which appeared at about 90°C was broadened and the intensity of the γ‐relaxation at −95°C in the tan δ‐versus‐temperature curve was lowered. The β‐relaxation which appeared at −45°C for the wet nylon 6 decreased its intensity.
Determination of mean molecular weight of polyethylene glycols by several physical methods
Authors: Taleb‐Bendiab Sid Ahmed , Vergnaud Jean‐Maurice 
Published: April 2003

AbstractSeveral physical methods were used for the determination of the mean molecular weight of polyethylene glycols (PEG). Gas chromatography proved to be the best method to obtain a molecular weight of PEG lower than 600 by using Tenax as a stationary phase. Reverse gas chromatography was long but valid for PEG between 400 and 3000. Viscosity measurements gave more suitable values by taking different Mark–Houwink constants according to the molecular weight of PEG. Gel permeation chromatography using the universal calibration method was shown reliable, and by means of three μ‐Styragel phases (100, 500, and 104 Å) the molecular weight range between 200 and 20,000 was covered. Infrared measurements were related to the molecular weight by taking the OH absorbing band, and a result for PEG of 5000 or less was obtained. Vapor pressure measurements as made in tonometry were an accurate and sensitive method.
Absorption of benzene by open‐cell polyurethane foams
Authors: Sefton Michael V. , Mann John L. 
Published: April 2003

AbstractThe rate of absorption of benzene by open‐cell polyurethane foams of varying pore size (30–85 pores per inch) has been shown to be dependent on the size of the foam samples. Mass transport from the bulk vapor to the matrix surface appears to be a significant resistance when compared with the rate of diffusion in the matrix itself. Even though these foams have a large permeability to air at low pressures, pore diffusion appears to be more significant than bulk flow in describing the absorption process, resulting in absorption behavior which is more characterstic of closed‐cell foams. A dual resistance model of the obsorption process, has been used to estimate matrix diffusivities and pore mass transfer coefficients. Although the model was inadequate in some regards to describe completely the absorption process, the significance of the unexpected pore diffusion resistance to mass transfer was quantified. The dependence of pore diffusion on foam size reflected the qualitative interpretation that was apparent from the absorption curves. While the reason for this anomalous behavior remains unknown, open‐cell foams cannot be considered simply as a high‐surface‐area thin‐walled form of the matrix material in describing the absorption process; the effect of foam size must also be considered.
Wrinkle‐resistant cotton by photoinitiated reaction with glycidyl methacrylate followed by crosslinking reactions
Authors: Reinhardt Robert M. , Arthur Jett C. , Muller Linda L. 
Published: April 2003

AbstractA wrinkle‐resistant cotton fabric was produced by photoinitiated free‐radical reaction of a glycidyl methacrylate monomer from a methanol‐water solution to form a poly(glycidyl methacrylate) copolymer, followed by crosslinking reactions of oxirane groups of the copolymer with cellulose. The product had increased conditioned and wet recovery angles and retained breaking and tearing strengths and stiffness values in the ranges normally obtained for wrinkle‐resistant cottons. The effects of these reactions on the fiber structure were determined by transmission electron microscopy. The modified fibers were resistant to dissolution in cupriethylenediamine dihydroxide.
UV‐irradiated ozonation of water‐soluble polymers
Authors: Imamura Seiichiro , Teramoto Masaaki , Ogawa Yukinobu , Teranishi Hiroshi 
Published: April 2003

AbstractThe effect of ultraviolet light on the ozonation of some water‐soluble polymers such as polyethylene glycol, polyacrylamide, carboxymethyl cellulose, and poly(vinyl alcohol) was investigated. Ultraviolet light irradiation accelerated the ozonation. Acceleration was caused by the decomposition of ozone by ultraviolet light, which produced active species.
Thermal degradation of polystyrene. I. Chain scission at low temperature in air
Authors: Gupta Mool C. , Nath Jaya D. 
Published: April 2003

AbstractThe thermal degradation of polystyrene was studied in air at temperature where volatile formation is neglible. Plots of degree of degradation α vs. t are linear and confirm the random nature of chain scission, but the intercepts are temperature dependent and the rate constant decreases with temperature, showing that oxygen plays a role in the chain‐end initiation and deactivation of the free‐radical centers. IR spectra indicate the formation of an acetophenone‐type structure during degradation. The kinetic analysis using various methods yield an activation energy value of 30–35 kcal/mole.
Permeation of oxygen through polyurethane–polyepoxide interpenetrating polymer networks
Authors: Chen Show‐An , Ju Hui‐Lin 
Published: April 2003

AbstractOxygen permeation studies on polyurethane (PU)/polyepoxide (EP) interpenetrating polymer networks show that the increased crosslinking density owing to additional permanent chain entanglement (resulting from interpenetration) can decrease the coefficients of permeation, diffusion, and oxygen solubility. At 20% PU, at which the crosslinking density is maximum, these coefficients retain minimum values, while the tensile strength retains a maximum value.
Compositional determination of 2,6‐dimethyl‐1,4‐phenylene oxide and styreen hompolymer blends by infrared spectrometry and pyrolysis gas chromatography
Authors: Mukherji Anil K. , Butler Marsha A. , Evans Donald L. 
Published: April 2003

AbstractCompositional analysis of 2,6‐dimethyl‐1,4‐phenylene oxide (PPO) and styrene homopolymer blends was accomplished using infrared spectrometry and pyrolysis gas chromatography. In infrared measurements the 1030/700 cm−1 absorption ratio provides percent PPO in the blends within ±3% of the actual value but with a σ% of ±10. In pyrolysis GC measurements, four peaks resulting from the fragmentation of the PPO molecule have been investigated for quantitation. One of these peaks provides results with ±2% of the PPO present with a σ% of 7 when the percent PPO in the blend is above 20.
Sorption kinetics for asymmetric binary and ternary laminate slabs in finite and semi‐infinite well‐stirred baths
Authors: Spencer H. Garth , Barrie James A. 
Published: April 2003

AbstractEquations describing the sorption kinetics of asymmertric membranes composed of AB and ABC laminate slabs in finite and in semi‐infinite well‐stirred baths are presented, and some properties of these systems are discussed.
Influence of diethylene glycol content on behavior of poly(ethylene terephthalate) fibers
Authors: Militký Jiří , Vaníček Jiří , Dostál Jan , Jansa Jaroslav , Čáp Jaroslav 
Published: April 2003

AbstractRelationship between structural parameters of poly(ethylene terephthalate) (PET) fibers, their mechanical properties, and nonisothermal sorption of disperse dyes are investigated. Influence of diethylene glycol (DEG) addition and small changes in draw ratio are studied. Mechanical properties are characterized by stress–strain curves at constant deformation rate. The stress–strain relationships are described by means of derivative analysis. For treatment of nonisothermal experiments a simple kinetic model is suggested enabling to determine activation parameters of sorption. Further, the influence of a blank dye bath on the structure and properties of PET fibers is studied.