bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal stability, morphological, dielectric, and conductivity characteristics of pyrrole modified poly‐N‐vinyl carbazole
Authors: Biswas Mukul , Roy Anindita 
Published: April 2003

AbstractN‐vinyl‐Carbazole (NVC) has been polymerized in the presence of pyrrole (PY) by anhydrous ferric chloride. The copolymer has been characterized by IR Spectroscopy. Thermal stability of P(PY–NVC) is intermediate between that of PNVC and PPY, respectively. DSC reveals a single glass transition break at 180–200°C for P(PY–NVC), which is higher than the Tg for polypyrrole (∼ 165°C), but is lower than that for PNVC (∼ 227°C). The XRD analysis reveals PPY to be totally amorphous and shows the percent crystallinity for P(PY–NVC) to be less than that of PNVC. Dielectric constants of the polymers follow the trend: PPY > P(PY–NVC) > PNVC, and fall sharply with the applied frequency to a limiting value. The polymers are characterized by a broad dielectric relaxation. DC conductivity is dependent on temperature and FeCl3/polymer mole ratio and at a particular temperature follows the trend: PPY > P(PY–NVC) > PNVC. © 1993 John Wiley & Sons, Inc.
A geometric determination of void production in an elastic pancake
Authors: Blatz Paul J. , Kakavas P. 
Published: April 2003

AbstractThe aim of this article is to adduce various theoretical approaches to evaluating the stress displacement field throughout a pancake sample. We shall attempt to produce an effective material property, veff, which is consistent with the measured values of γ = −u0(a)/aε (normalized volumetric contraction), the initial modulus from the triaxial tests on compression, Mcompr, and tension, Mtens. In order to obtain analytical expressions relating γ and (M/E)tens to veff, we used the simplest finite element mesh. Taking the given aspect ratio of the pancake \documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {\frac{{\rm D}}{{\rm h}} \approx 16} \right) $$\end{document}, the shear modulus G = 60 psi, and the measured γ = 0.23, it was found that the effective Poisson's ratio is veff ≈ 0.492 and the initial modulus in tension Mtens = 2990 psi. Using Warren's equation, one obtains the volume fraction of voids from the determined effective material property veff. It was found that the volume fraction of voids α grows from 0.002 to 0.021. © 1993 John Wiley & Sons, Inc.
Influence of molecular weight on the resistance of polylactide fibers by radiation sterilization
Authors: Horáček I. , Kudláček L. 
Published: April 2003

AbstractThe mechanical properties and in vitro degradability of poly(L‐lactide) fibers with different average molecular weights, prepared by a dry spinning–hot drawing process from CHCI3 solutions, were studied in relation to the γ‐irradiation dose. In the range of molecular weight of 1.6−3.6 × 105, no differences were found in the relative decrease of tensile strength after irradiation of 25 kGy. Changes of the elongation at break are discussed in terms of a network solution theory. In vitro degradation of the fibers is also discussed in network solution theory terms. Regardless of the courses of degradation curves, it may be stated that all prepared fibers could be sterilized by γ‐rays and the rate of degradation was not affected by the irradiation dose. © 1993 John Wiley & Sons, Inc.
Composites from benzylated wood and polystyrenes: Their processability and viscoelastic properties
Authors: Hon David N.‐S. , Chao Wayne Y. 
Published: April 2003

AbstractUtilization and conservation of raw materials are two of the main thrusts of our research. Several plasticized woods have been prepared from sawdust in our laboratory. They possess unique thermal, mechanical, and viscoelastic properties. In this study, benzylated wood was used to blend with polystyrene to prepare a wood/plastic composite. Its dynamic processability and viscoelastic properties were evaluated. The mixtures with different blending ratios (benzylated wood/polystyrene) were prepared by mixing them in an intensive mixing device. The specific energy required to do the processing work decreased with the increase of benzylated wood in the composite. The mixture can be molded or extruded easily. The study of the viscoelasticity of the compression‐molded composite products using a dynamic mechanical thermal analyzer (DMTA) revealed, regardless of the mixing ratios, a single damping peak (tan δ). This suggested good compatibility between the two polymers. The glass transition temperature and the storage modulus of these composites decreased as the amount of benzylated wood increased. A composite with comparable mechanical properties of polystyrene was obtained from those composites with mixing ratios (benzylated wood/polystyrene) ranging from 0.4 to 0.6. © 1993 John Wiley & Sons, Inc.
Micron‐sized polymeric microsphere by suspension polymerization
Authors: Kamiyama Masafumi , Koyama Kikuhiko , Matsuda Hideomi , Sano Yoshiki 
Published: April 2003

AbstractA new suspension polymerization process that generates narrow‐size distribution and spherical particles in the range of 3–10 microns is described. In the new process, the monomer and water phases are held in separate vessels and fed at an accurate rate to a mechanical disperser, where small, uniform droplets of monomer are formed. The monomer droplets are then fed to a reaction vessel where the monomer is polymerized. The size of the polymerized particles can be effectively controlled by adjusting the disperser speed. A scanning electron microscope was employed to show the spherical nature of the particles. © 1993 John Wiley & Sons, Inc.
Rheological behavior of poly(1,4‐butylene isophthalate) containing sodium sulfonate groups
Authors: Munari Andrea , Fiorini Maurizio , Pezzin Giovanni , Pilati Francesco 
Published: April 2003

AbstractThe steady‐state rheological behavior in the melt of poly(1,4‐butylene isophthalate)s containing various amounts of sodium sulfonate groups has been investigated using a capillary rheometer. It has been found that the presence of SO3Na groups strongly enhances the melt viscosity and this result cannot be explained as due to the small increase of the glass transition temperature, but has to be attributed to the relevant interactions between ionic groups. Measurements carried out at different temperatures in the range 190–220°C have shown that the “Newtonian” viscosity of sulfonated poly(1,4‐butylene isophthalate) is well correlated to temperature by an Arrhenius‐type equation. The activation energy for melt flow has been found to increase linearly with SO3Na group content in the polymer. Fur‐thermore, it has been found that for samples having a content of ionic groups of 5% or higher and a sufficiently high molecular weight the time–temperature superposition principle does not hold. © 1993 John Wiley & Sons, Inc.
Fourier transform infrared analysis of hexamethyldisiloxane layers obtained in low‐frequency glow discharge
Authors: Radeva E. , Tsankov D. , Bobev K. , Spassov L. 
Published: April 2003

AbstractPolymer layers from hexamethyldisiloxane (HMDSO) up to 1 μm were produced by glow discharge at 50 Hz under different polymerization conditions. The Fourier transform infrared (FTIR) spectra of such layers were obtained at different current densities of the glow discharge (0.53 to 3.10 mA/cm2), substrate temperatures from 35 to 125°C; gaseous phase pressures from 13.3 to 266 Pa, and layer thicknesses from 0.2 to 0.6 μm. The FTIR spectra of polyhexamethyldisiloxane (PHMDSO) layers modified after treatment in ammoniacal plasma were studied. The spectra of layers obtained in plasma containing both monomer and ammonia vapors were also analyzed. © 1993 John Wiley & Sons, Inc.
Reinforcement of epoxidized natural rubber by carbon black: Effect of surface oxidation of carbon black particles
Authors: Roychoudhury A. , De P. P. 
Published: April 2003

AbstractEpoxidized natural rubber (ENR) reacts with surface oxygen groups of carbon black. The higher the concentration of these groups, the higher the intensity and the extent of reaction and the better the reinforcing ability of the black. Oxidized furnace blacks and channel blacks, which are known to have high quantities of oxygen functional groups, are thus more reinforcing than are the conventional furnace blacks, particularly in the case of black‐filled epoxidized natural rubber. © 1993 John Wiley & Sons, Inc.
Polymerization of olefins through heterogeneous catalysis. XIV. The influence of temperature in the solution copolymerization of ethylene
Authors: Jaber Isam A. , Ray W. Harmon 
Published: April 2003

AbstractThe influence of temperature variation on the kinetics and the polymer properties in the homo‐ and copolymerization of ethylene in a solution reactor is discussed. The Polymerization is conducted in a semibatch mode at 320 Psig total reactor pressure for 10 min polymerization time. Temperature variations in the range 145–200°C in both home‐and copolymerization of ethylene with 1‐octene shows that the highest catalyst yield was obtained at temperature of 165–175°C. At the optimal temperature, a high initial maximum in the rate of ethylene consumption is attained in a few seconds followed by a relatively slow decay when compared with polymerization conducted at higher temperatures. Polymerization at temperatures ≥ 185°C resulted in a lower peak in the consumption rate of ethylene accompanied by a rapid decay with time. In the case of ethylene/1‐Octene copolymerization, a rather low comonomer incorporation level is obtained at the conditions employed; the 1‐octene incorporated was only 0.2–0.7 mol %. Higher Mw values, of about 350,000 at 145°C, are obtained in homopolymerization in comparison to Mw values obtained in copolymerization, of about 195,000 at the same temperature. Over the temperature range of 145–200°C, both Mw and Mn values vary by about 40%. © 1993 John Wiley & Sons, Inc.
Polymerization of olefins through heterogeneous catalysis. XV. The influence of pressure in the solution copolymerization of ethylene
Authors: Jaber Isam A. , Ray W. Harmon 
Published: April 2003

AbstractThe high‐temperature solution homopolymerization of ethylene and copolymerization with 1‐hexene using highly active TiCl4/MgCl2‐supported catalyst was studied. Experiments with pressure variations in the range 100–400 Psig were carried out at 185°C and for 10 min polymerization time. Both peak initial rate of polymerization and the catalyst productivity in homo‐ and copolymerization were found to increase steadily with increasing reactor pressure. Higher polymerization rates arose in copolymerization compared to homopolymerization, especially above 200 Psig total pressure. In both cases, the reaction order with respect to ethylene concentration was close to two. The number‐average molecular weight was found to be almost independent of pressure, whereas in copolymerization, the weight‐average molecular weight was observed to decrease from about 200,000 to 120,000 over the range of pressure studied. The polydispersity index in copolymerization was found to decrease steadily from 8 to about 4 with increasing pressure. © 1993 John Wiley & Sons, Inc.
Radiation cross‐linking of ethylene vinyl alcohal copolymer functionalized with m‐isopropenyl‐α,α‐diamethyl benzyl isocyanate
Authors: Ekman Kenneth B. , Näsman Jan H. 
Published: April 2003

AbstractAn ethylene vinyl alcohal copolymer was functionalized with m‐isopropenyl‐α,α‐dimethyl benzyl isocyanate using reactive processing in a mixer. The Functionalization introduces pendant unsaturation to the polymer, which allows radiation cross‐linking to gel contents > 70% at radiation doses below 100 kGy. Unfunctionalized ethylene vinyl alcohal copolymer, on the other hand, forms no gel upon irradiation. The functionalization was completed within a few minutes of reactive mixing, which was confirmed with both FTIR and 13C‐NMR measurments.The oxygen permeability of ethylene vinyl alcohal copolymer increased with increasing degree of functionalization, and irradiation of the samples formed trapped radicals, which act as oxygen scavengers. Consequently no oxygen permeability was detected. However, radical activity was inhibited by annealing the samples at 110°C resulting in a 24% higher oxygen permeability values of the irradiated unfunctionalized samples were approximately 13% lower.Laminates of m‐isopropenyl‐α,α‐dimethyl benzyl isocyanate functionalized ethylene vinyl alcohal copolymer and m‐isopropenyl‐α,α‐dimethyl benzyl isocyanate functionalized ethylene vinyl hydroxyethyl methacrylate copolymer acquired improved adhesive strength both at dry and wet conditions as well as at elevated temperatures upon exposure to radiation. © 1993 John Wiley & Sons, Inc.
An aqueous‐base developable photoresist based on light‐induced cationic polymerization: Resist performance of poly(glycidyl methacrylate‐co‐methacrylic acid)
Authors: Naitoh Kazuhiko , Koseki Ken'ichi , Yamaoka Tsuguo 
Published: April 2003

AbstractAn aqueous‐base developable photoresist based on photoinduced cationic polymerization has been prepared by copolymerization of glycidyl methacrylate (GMA) and methacrylic acid (MAA). The copolymer containing 83 mol% of GMA unit is soluble in an aqueous base and crosslinked in the presence of photogenerated acid caused by acid‐initiated ring‐opening polymerization of pendant epoxide groups. Exposure results in the generation of acid and the subsequent baking process promotes the diffusion of photogenerated acid, which initiates the cationic crosslinking of the epoxide rings. It was also found that the sensitivity of the copolymer was remarkably enhanced when a divinyl ether monomer is added as a bifunctional crosslinker. The sensitivity enhancement may be caused by the high reactivity of the divinyl ether monomer in the presence of acid. The resist comprised of the copolymer, the vinyl ether monomer, and diphenyliodonium 9,10‐dimethoxy‐an‐thracene‐2‐sulfonate as photoacid generator exhibited the sensitivity of 20 mJ/cm2. A good pattern profile with high resolution was attained by exposure to a 365 nm light followed by a postexposure bake at 60°C for 3 min. © 1993 John Wiley & Sons, Inc.
Structural effects on vapor diffusivity in rigid polymers
Authors: Hsu W. P. , Xu Z. S. , Okamoto Y. , Myerson A. S. , Kwei T. K. 
Published: April 2003

AbstractSulfonated aromatic polyamide and different salts were synthesized. Water vapor diffusion in these polymers and X‐ray diffraction of these polymers before and after water immersion were studied. The concentration dependence of the diffusivity is related to the morphological structure in the dry state and the change induced by absorbed water. © 1993 John Wiley & Sons, Inc.
Characterization of new hindered amine light stabilizers
Authors: Lau Wayne W. Y. , Lee C. S. , Goh S. H. , Lee S. Y. , Pan Jiangqing , Song Yu 
Published: April 2003

AbstractNew polymerizable urethane functional monomers containing hindered amine (III, III′) and their copolymers with styrene (S) and methyl methacrylate (MMA) are characterized and tested as hindered amine light stabilizers (HALS). Experimental results indicated that the monomers possess high photostabilizing effectiveness comparable to that of Tinuvin 770 and Tinuvin 765. Their copolymers with S and MMA showed lower photostabilizing effectiveness mainly due to the low hindered amine content in the copolymers. The copolymers, however, showed very high resistance to liquid extraction. UV and ESR analyses indicate that the photostabilizing mechanism of these HALS is through the scavenging action of nitroxyl radicals formed from degradation of the substrate polymer. © 1993 John Wiley & Sons, Inc.
Optical and electrical characteristics of electrodeposited polypyrrole films
Authors: Misra S. C. K. , Beladakere N. N. , Pandey S. S. , Ram M. K. , Sharma T. P. , Malhotra B. D. , Chandra Subhas 
Published: April 2003

AbstractThe optical and electrical properties of BF−4 deposed polypyrrole (PPY) have been studied in detail. The effect of annealing on the optical and electrical properties of BF−4 doped PPY is reported. Interestingly, these properties are modified with annealing and it is observed that PPY is similar to other inorganic amorphous semiconductors. It is also seen that the electrical and optical properties of BF−4 doped PPY are stabilized after 70 h of annealing at 70°C. © 1993 John Wiley & Sons, Inc.
Coemulsion and electrodeposition properties of mixtures of cationic epoxy resin and cationic acrylic resin containing butoxymethylamide groups
Authors: Yang Chin‐Ping , Chen Yahn‐Haur 
Published: April 2003

AbstractButyl acrylate, styrene, N,N‐dimethylaminoethylmethacrylate, and N‐(n‐butoxymethyl) acrylamide were copolymerized to prepare a cationic acrylic copolymer (I) containing butoxymethylamide groups. This copolymer can be mixed with an epoxy‐amine adduct (II), acetic acid, and deionized (D.I.) water to form a coemulsion containing two cationic resins. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the deposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform Infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer‐surfacer (pricer) electrodeposition paint was also discussed. The results indicate that at any coemulsion resin composition the resin composition of electrodeposited film is almost equal to the coemulsion resin composition. The throwing power of emulsion increases with increasing applied voltage, as expected. However, the throwing power of coemulsion is almost equal to that of the II emulsion but greater than that of the I emulsion. Furthermore, all cured films derived from mixtures of I/II show excellent adhesive strength, good hardness, and high levels of salt spray resistance. © 1993 John Wiley & Sons, Inc.
Three‐dimensional solubility parameters and chemical protective clothing permeation. II. Modeling diffusion coefficients, breakthrough times, and steady‐state permeation rates of organic solvents in Viton® gloves
Authors: Zellers Edward T. , Zhang Guo‐Zheng 
Published: April 2003

AbstractThree‐dimensional (3‐D) solubility parameters are used in separate models of the solubility, S, and diffusion coefficient, D, of organic solvents in polymers. Modeled values of these variables are then combined in Fickian diffusion equations to estimate solvent breakthrough times (BT) and steady‐state permeation rates (SSPR). Published data on the permeation of 18 solvents through commercial Viton® glove samples are used to test the accuracy of the approach. Estimates of S are determined based on the model described in the preceding article. Of several empirical correlations investigated to model D, best results are achieved using the product of the solvent molar volume, V1, and either the weighted solvent‐Viton 3‐D solubility parameter difference, Aw, or the Flory interaction parameter, X, also calculated from 3‐D solubility parameters. To account for the change in the value of D over the course of the permeation test, D values are evaluated at breakthrough and steady state. Modeled BT values within a factor of three of experimental values (typically within a factor of two) are obtained for the 15 solvents for which analytical detection limits were reported. Modeled SSPR values within a factor of six of experimental values (typically within a factor of four) are obtained for the 15 solvents with valid SSPR measurements. © 1993 John Wiley & Sons, Inc.
Formation and textures of ethyl‐cyanoethyl cellulose/acrylic acid mesophase
Authors: Jiang S. H. , Huang Y. 
Published: April 2003

AbstractThe formation, textures, and optic characteristics of the ethyl‐cyanoethyl cellulose [(E‐CE)C]/acrylic acid (AA) mesophase were studied using polarizing microscopy, spectro‐photometry, and small‐angle light scattering (SALS). The disklike, oily streak, planar, pseudoisotropic, polygonal textures and the texture of domains gathered randomly were observed in the mesophase. The polygonal texture in unitary mesomorphic solutions can be regarded as the texture from the combination of deformed mesophase aggregates with the disclike texture. The mesomorphic solution exhibits vivid colors when the concentration is about 42‐52 wt % because of its selective reflection to visible light. The wavelength of the light that is selectively reflected shifts to the shorter wavelength, with increasing concentration. © 1993 John Wiley & Sons, Inc.
Graft copolymerization of methylmethacrylate onto caesarweed fibers by the potassium permanganate–toluene redox system
Authors: Eromosele Ighodalo C. , Hamagadu Theophilus J. 
Published: April 2003

AbstractPreliminary investigations have been conducted on the graft copolymerization of meth‐ylmethacrylate onto Caesarweed fiber, initiated by potassium permanganate and the toluene redox system. The percentage graft yield increased with permanganate up to 132% in the concentration range, 1.0×10−2 to 5.0×10−2 M at 40°C. The effects of varying concentrations of toluene, acids, and monomer on graft yield were also investigated. Graft yield increased initially and then decreased on varying the concentrations of toluene from 2×10−2 to 20×10−2 M. The graft yield increased with temperature between 20 and 50°C. At 60°C, the graft yield decreased considerably by up to 60% of the value at 50°C. The calculated activation energies for the overall reaction, and for the initiation process, are 9.15 and 9.30 Kcal mol−1, respectively. © 1993 John Wiley & Sons, Inc.
Thermolysis of orthonovolaks. II. Phenol–formaldehyde and α‐naphthol–formaldehyde resins
Authors: Chetan M. S. , Ghadage R. S. , Rajan C. R. , Gunjikar V. G. , Ponrathnam S. 
Published: April 2003

AbstractA series of α‐naphthol‐formaldehyde orthonovolak resins were synthesized by altering the mol ratios of α‐naphthol and formaldehyde involved in the condensation reaction. Oxalic acid was used as the catalyst. The softening temperatures and thermal degradation behavior of these resins are presented. Thermal degradation kinetics of these resins were investigated by applying nonisothermal integral methods of Coats–Redfern and Horowitz–Metzger. The dynamic thermogravimetric experiments were conducted in air to obtain differential ther‐mogravimetric (DTG) plots. The ratio of the partial integrated area at temperature T to the total area was used to estimate the fractional degradation in the analysis. Degradation proceeded in two stages. The second stage was the predominant one. The thermal degradation profile and activation energies in this stage are discussed in relation to orthonovolaks of similar composition based on phenol–formaldehyde. © 1993 John Wiley & Sons, Inc.