bluuebunny/crossref_metadata_2025 huggingface dataset:
Dialkyldithiophosphate substituted on poly(vinylchloride): Synthesis and performance
Authors: Bromberg Lev , Levin Gideon
Published: April 2003

Preparation of sodium salt of di(2‐ethylhexyl)dithiophosphoric acid (DTPANa) by reaction of the corresponding DTPA with sodium hydride has been described. Nucleophilic substitution of chlorine on poly(vinylchloride) (PVC) by a di(2‐ethylhexyl)dithiophosphate group resulting in modified polymer (MP) was characterized by the second order rate constant equal to 6.6 × 10−5 M−1 s−1. Formation of homogeneous stable gelled phases composed of MP and DTPA, as well as MP, PVC, and DTPA, was demonstrated. The gelled material is capable of selective separation of metal ions under the conditions of extraction chromatography. © 1993 John Wiley & Sons, Inc.
Polymerization of olefins through heterogeneous catalysis XI: Gas phase sequential polymerization kinetics
Authors: Chen C. M. , Ray W. H.
Published: April 2003

A unique series of ethylene and propylene sequential polymerization experiments have been carried out in a stirred bed gas phase reactor using unsupported Stauffer AA catalyst (TiCl3· \documentclass{article}\pagestyle{empty}\begin{document}$\frac{1}{3}$\end{document}AlCl3). Several interesting kinetic results were observed. It was found that propylene causes rate enhancement for a subsequent ethylene polymerization but that ethylene causes a rate reduction for a subsequent propylene polymerization. Furthermore, the rate enhancement/reduction effect increases with the duration of the preceding polymerization. Chemical/kinetic effects were found to be the likely causes of both the rate enhancements and the rate reductions observed during sequential polymerization. It was also shown that enhanced monomer sorption caused by the presence of a more soluble component, such as a heavier comonomer, does contribute to rate enhancement during simultaneous copolymerizations, but is not a factor for sequential polymerizations. © 1993 John Wiley & Sons, Inc.
Meadowfoam monoenoic fatty acid amides as slip and antiblock agents in polyolefin film
Authors: Swanson C. L. , Burg D. A. , Kleiman R.
Published: April 2003

Mixed monounsaturated amides (MMA) of fatty acids from meadowfoam (Limnanthes alba) were effective slip and antiblocking agents for polyethylene films. MMA may compete with extant amides as additives for manufacture of PE films if their selling price is competitive. The MMA (79% cis‐5‐eicosenoic acid amides, 17% cis‐5‐, and cis‐13‐docosenoic acid amides, and 1% cis‐5, cis‐13‐docosadienoic acid amide) required > 500 ppm but < 1000 ppm dosage to achieve high slip (coefficient of friction < 0.2) within 10 minutes of film blowing. For comparison, erucamide required < 250 ppm, oleamide required < 500 ppm, and stearamide required > 1000 ppm to give high slip levels within 10 min. Maximum antiblocking effectiveness of MMA, which developed at 1000 ppm, was equivalent to stearamide at 1000 ppm. © 1993 John Wiley & Sons, Inc.§
Polymerization of olefins through heterogeneous catalysis. XII. The influence of hydrogen in the solution copolymerization of ethylene
Authors: Jaber Isam A. , Ray W. Harmon
Published: April 2003

The copolymerization of ethylene with highly active TiCl4/MgCl2‐supported catalysts in solution reactors at 185°C and 400 Psig pressure is presented. The performance of these supported catalysts at these conditions is characterized by a high initial rate that decays rapidly within the 10 min polymerization period. In the presence of hydrogen and a comonomer, catalyst yields up to about 300 kg/g (Ti) are achieved. The kinetic data indicate rate enhancement when hydrogen is added in moderate concentrations. However, a high concentration of hydrogen results in a decreasing rate of ethylene consumption. Increasing the H2/C2molar ratio in the range 0–10.66 ċ 10−3leads to a reduction in theMnvalues from 31,600 to 17,400. © 1993 John Wiley & Sons, Inc.
Electrical properties of poly(vinyl chloride) compositions
Authors: Saad A. L. G. , Hassan A. M. , Gad E. A. M.
Published: April 2003

A sample of poly(vinyl chloride) (PVC) and a polar plasticizer consisting of dioctyl phthalate (DOP) and dibutyl phthalate (DBP) was prepared and found to possess inconvenient electrical properties (permittivity, dielectric loss, and conductivity). Different samples of PVC compositions were formulated from the PVC–DOP–DBP system and also variable proportions of a copolymer of 1‐octadecene‐maleic anhydride or its hexadecylester. Lead stearate as a heat stabilizer and kaolin as a filler were added. The effect of copolymer structure on the electrical properties of the PVC–DOP–DBP system was studied to obtain a plasticized PVC of good electrical insulation character. © 1993 John Wiley & Sons, Inc.
Effect of acrylonitrile content of styrene‐co‐acrylonitrile (SAN) on morphology and electrooptical properties of polymer/liquid crystal composite films
Authors: Kim B. K. , Ok Y. S.
Published: April 2003

Effects of copolymer composition on morphology and electrooptical properties of polymer/liquid crystal (LC) (40/60 w/w) composite films were studied with styrene‐co‐acrylonitrile (SAN) of varying acrylonitrile (AN) content (6.3–35 wt %) and a cyanobiphenyl‐type liquid crystal (E8). The dimension of the LC domain in the composite film decreased with increase of AN content of SAN up to 30 and increased at 35 wt %. The contact angle of the film with an LC drop showed a similar trend; however, its minimum was obtained at 24% AN. Threshold voltage (Vth) and rise time (τR) increased, and decay time (τD) decreased with AN content up to 30%, and the tendency is reversed at 35%. The results were interpreted in terms of, possibly, a solubility parameter matching between SAN and LC. © 1993 John Wiley & Sons, Inc.
On the applicability of the Lennard‐Jones potential function to amorphous high polymers
Authors: Arends C. B.
Published: April 2003

Pressure‐volume‐temperature measurements were performed on five amorphous thermoplastics. From these data, first derivatives of internal energy with respect to volume were calculated. These derivatives were cast into the Lennard‐Jones form and the two defining parameters were evaluated for each polymer. It was found that, when the polymer is in the glassy state, these parameters correspond to the volume and internal energy of the polymer at absolute zero. For melts, the first derivatives are constant within the accuracy of these experiments regardless of temperature, pressure, or volume. As a result, the Lennard‐Jones potential was found to be a good model for the amorphous glassy state and inappropriate above Tg. © 1993 John Wiley & Sons, Inc.
The maleinization of low molecular weight guayule rubber
Authors: Thames S. F. , Rahman A. , Poole P. W.
Published: April 2003

The reactions of low molecular weight Guayule rubber (LMWGR) and maleic anhydride (MA) at varying mole ratios were studied in the polar solvent, cyclohexanone, and in p‐xylene, a nonpolar solvent, by conventional free radical catalysis. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) were used to confirm product formation and identification. © 1993 John Wiley & Sons, Inc.
Polyurethane networks based on poly(ethylene oxide)
Authors: Zulfiqar M. , Quddos A. , Zulfiqar S.
Published: April 2003

A wide range of infinite urethane polymer networks were prepared from poly(ethylene glycol) (PEG) and hexamethylene diisocyanate (HMDI) using 1,1,1‐tris‐(hydroxymethyl) ethane (THME) as the cross‐linking agent. The influence of temperature, cross‐linking, and crystallinity on the swelling character of the hydrogel has been discussed. The toxicity of the network polymer by intravaginal implants in rats was studied. Implantation of the polymer did not result in alteration in behavior and feed intake or any pathological changes in the tissue. Vaginal fluids from the polymer‐implanted rats or the polymer extract when inoculated on a listeria monocytogene culture plate were unable to inhibit the bacterial growth. © 1993 John Wiley & Sons, Inc.
Ionotropic crosslinking of sodium carboxymethylcellulose and sodium carboxymethylcellulose‐gelatin matrices and their erosion properties
Authors: Prasad M. P. , Kalyanasundaram M.
Published: April 2003

Hydrophilic sodium carboxymethylcellulose (NaCMC) matrices were chemically modified into hydrophobic gels by ionotropic crosslinking with cupric or ferric ion under ambient temperature and pH. Insoluble matrices were also prepared using an interactive polymer gelatin in combination with NaCMC. These matrices underwent erosion at the crosslinks, followed by matrix erosion when released in water. The matrix erosion in water was influenced by the gelling agent, initial crosslinker density, and gelatin content in the insolubilized matrices. The apparent diffusion coefficients of fenthion ranged from 7.2 × 10−9 to 175.6 × 10−9 cm2/sec, with matrices prepared under different conditions. These erosion‐controlled matrices can be used for the controlled release of various biologically active agents. © 1993 John Wiley & Sons, Inc.
Thermal stability, morphological, dielectric, and conductivity characteristics of pyrrole modified poly‐N‐vinyl carbazole
Authors: Biswas Mukul , Roy Anindita
Published: April 2003

N‐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

The 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

The 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

Utilization 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

A 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

The 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

Polymer 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

Epoxidized 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

The 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

The 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

An 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

An 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

Sulfonated 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

New 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

The 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

Butyl 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

Three‐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

The 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

Preliminary 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

A 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.
Preparation of new hydrophilic and durable porous polymer particles
Authors: Terauchi Ken‐Ichi
Published: April 2003

A preparation method for new highly durable hydrophilic porous polymer particles consisting of acrylic monomers and copolymerizable cross‐linking agents was studied. In the case of using only a two‐functional acrylic monomer as the cross‐linking agents, the obtained particles had a relatively low mechanical strength, but by the addition of a multifunctional acrylic monomer into the above system, it was found that the porous particles obtained became highly durable and showed excellent mechanical strength of more than 500 kg/cm2. The effect of preparation conditions on the specific surface area of these particles consisting of three components was investigated from the following viewpoints: The first was aimed at the stabilized phase of droplets consisting of monomer/cross‐linkers/porogen under various conditions of aqueous poly(vinyl alcohol) (PVA) media, and the second was the effect of composition changes of the monomer and cross‐linkers on the inner porous structure of the particles obtained. Thus, the specific surface area of the particles was found to be significantly affected both by the degree of saponification (DS) of PVA and by the change of composition. On the other hand, the average pore radius of typical particles obtained in this way can be controlled in the range from 40 to 120 Å by the weight ratio of chlorobenzene as the porogen. Furthermore, the mechanical stability and durability of the column packed with the porous particles obtained were discussed. © 1993 John Wiley & Sons, Inc.
Study on physical properties of poly(vinyl acetate) emulsion films obtained in batchwise and in semicontinuous systems
Authors: Okaya Takuji , Tanaka Taku , Yuki Ken
Published: April 2003

Emulsion polymerization of vinyl acetate was carried out batchwisely or semicontinuously in the presence of a nonionic surfactant or poly(vinyl alcohol) (PVA). From the investigation of degrees of polymerization of poly(vinyl acetate) (PVAc) during the course of polymerization and those of corresponding hydrolyzed PVA, it was clarified that the degrees of polymerization of the batchwise system are much larger than those of the semicontinuous system, and long branches and shorter branches are formed in the batchwise and the semicontinuous systems, respectively. The emulsion films obtained batchwisely had properties with better tensile strengths by two to four times (nonionic system) and 1.5 times (PVA system) than those obtained semicontinuously. The former films revealed a better water‐resistant nature compared with the latter films. © 1993 John Wiley & Sons, Inc.
Preparation and application of low molecular weight poly(vinyl chloride). III. Mechanical properties of blended poly(vinyl chloride)
Authors: Yamamoto Kikuo , Maehala Takashi , Mitani Katsuo , Mizutani Yukio
Published: April 2003

The blending effect of poly(vinyl chloride) with relatively higher molecular weight (HMW‐PVC) and relatively lower molecular weight (LMW‐PVC) has been investigated by measuring various mechanical properties: melt properties, tensile strength, tensile modulus, and impact strength. The blended PVC has slightly improved melt properties in comparison with the HMW‐PVC used. The tensile strength of the blended PVC is related to the weight‐average polymerization degree (Pω) of LMW‐PVC and the LMW‐PVC content. At the LMW‐PVC content of 20%, the tensile strength of blended PVC is a maximum: approximately 58 MPa. © 1993 John Wiley & Sons, Inc.
Polyester‐modified poly(ethylene ether carbonate) polyols by molecular weight advancement
Authors: Harris Robert F.
Published: April 2003

Poly(ethylene ether carbonate) polyols can be modified by chemical reactions with polyester polyols, poly(carboxylic acids), poly(carboxylic acid) esters, or poly(carboxylic acid) cyclic anhydrides under conditions of elevated temperatures and reduced pressures to give estermodified poly(ethylene ether carbonate) polyols. Polyester polyols and poly(carboxylic acid) ester are incorporated into the polymer backbone by transesterification/ advancement reactions. Poly(carboxylic acids) and poly(carboxylic acid) cyclic anhydrides first undergo esterification and then transesterification / advancement reactions. Molecular weight builds in a predictable manner and can be controlled by the amount of distillate removed. The processes have been characterized by following the distillate formation and composition as a function of reactor temperature and product molecular weight build. The products have been characterized by molecular weight and carbon‐13 NMR spectroscopy. A new family of ester‐modified poly(ethylene ether carbonate) polyols has been prepared, most of which were not available with prior technology. These polyols are useful in polyurethane applications, where the degree and type of poly modification can be used to adjust polyurethane properties. © 1993 John Wiley & Sons, Inc.
Novel cycloaliphatic epoxy resins. II. Curing reaction with BF3MEA and its cured properties
Authors: Tokizawa Makoto , Okada Hiroyoshi , Wakabayashi Nobukatsu
Published: April 2003

The BF3MEA curing reaction and the cured properties of novel cycloaliphatic epoxy resins (CE‐resins), which were derived from an octadienyl compound, were studied. Gelation time and the DSC scan of the CE resins, with BF3MEA hardener, proved that the reactivity of the CE resins is intermediate among the reactivities of the conventional resins; it was found that the CE resins react faster than DGEBA, but slower than the conventional cycloaliphatic epoxy resins. The pot life of the CE‐ (III) resin with BF3MEA hardener proved to be over 30 days at a temperature of 20°C. The thermal properties are affected by the amount of BF3MEA used and the curing conditions. CE‐(III) showed the highest HDT of over 200°C with 2–3 phr of BF3MEA. The flexural properties of CE‐(I) proved to be flexible and tough. CE‐(II) exhibited the highest strength and elongation, while CE‐(III) had the same flexural properties as DGEBA. Furthermore, the blending of CE‐(II) with DGEBA produced greater flexural strength and greater elongation than each original resin had. The thermal stability at elevated temperature and the water resistance of the cured CE resins proved to be inferior to those of DGEBA and novolac epoxy resin, probably due to the use of BF3MEA. These results suggest the CE resin will provide a new application for a one‐component curing system for composites. © 1993 John Wiley & Sons, Inc.
Dynamic rheological studies of hydrophobic interactions in injectable collagen biomaterials
Authors: Rosenblatt Joel , Devereux Brian , Wallace Donald G.
Published: April 2003

Injectable collagen is a concentrated dispersion of collagen fibers in aqueous solution that is used to correct dermal contour defects through intradermal injection. The effect of hydrophobic forces on the rheology of concentrated dispersions of collagen fibers was studied by dynamic rheological measurements over temperatures ranging from 283 to 308 K. The results are interpreted in terms of the associated relaxation time spectra and the theory of Kamphuis et al. for concentrated dispersions. Increases in fiber rigidity are seen from a progressive decrease in the slope of the linear log G′ (or G″) vs. log ω data recorded for these dispersions as temperature is increased. A molecular interpretation of this result was obtained by treating collagen fibers as a liquid crystalline phase of rigid‐rod collagen molecules that have phase‐separated from aqueous solution. Hydrophobic forces affect the volume fraction of water that is present in the phase‐separated fibers, which, in turn, affects the rigidity of the fibers. Distinct yielding behavior (in the nonlinear viscoelastic region) occurs at temperatures above 293 K and reflects a gel transition. Thermal gelation of collagen dispersions is proposed to proceed through hydrophobically driven mechanisms of increased fiber rigidity and enhanced interfiber attractive forces. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of amide linkage‐incorporated polyethyleneimine‐based chelating resins and studies of the crosslink density and surface properties on metal ion uptake
Authors: Thiagarajan N. , Subbaiyan M.
Published: April 2003

The chelating resins incorporating amide linkages were synthesized in open reaction vessels (OV) by polycondensing different proportions, viz., 1 : 1, 1 : 1.3, and 1.3 : 1 of polyethyleneimine (PEI) and diethylenetriaminepentaacetic acid (DTPA), respectively, at 145–155°C, and at varying curing times (15 h and 22 h). For the proportion 1 : 1, the synthesis was performed in a closed reaction vessel (CV) as well. The resins were characterized by FTIR, elemental, and thermogravimetric analysis, apart from sarptometric surface studies. The extent of crosslinking was evaluated by swelling measurements and the chemical stability was assessed by acid and alkali treatment. The effect of the mode of heating and curing times on the extent of crosslinking and pore structure modifications were evaluated. The influence of these factors on the capacities, the kinetics, and the break through curve trends of these resins were studied using zinc and cadmium metal ions as references. The reproducibility of the resins were ascertained by assessing the extent of change in the break through curve trends of their different batches, synthesized under identical conditions. © 1993 John Wiley & Sons, Inc.
Surface and interfacial FT–IR spectroscopic studies of latexes. VIII. The effect of particle and copolymer composition on surfactant exudation in styrene‐n‐butyl acrylate copolymer latex films
Authors: Kunkel Jeremy P. , Urban Marek W.
Published: April 2003

Polarized attenuated total reflection Fourier transform infrared (ATR FT–IR) spectroscopy was used to identify the mobility and surfactant exudation of sodium dioctyl sulfocuccinate (SDOSS) surfactant molecules to the film–air (F–A) and film–substrate (F–S) interfaces in styrene/n‐butyl acrylate (Sty/n‐BA) latex films. It was found that, depending upon the latex particle composition, the surfactant molecules could be driven to the F–A or F–S interfaces. The primary factors that governed the direction of exudation were the compatibility of the latex components, interfacial film‐substrate surface tension, and the chemical composition of the latex particles. Concentration, as well as orientation, of the hydrophilic SONa+ surfactant ends changed as a function of depth and the latex particle composition. © 1993 John Wiley & Sons, Inc.
Heat treatment studies of a TLCP fiber
Authors: Sarlin Juha , TörmäLä Pertti
Published: April 2003

This work deals with the heat treatment of fibers and nonoriented specimens made of the thermotropic liquid crystalline polymer Vectra A900 in the light of tensile properties and DSC measurements. In calorimetric measurements, there seem to be some differences in the effects of the treatment between macroscopically isotropic (nonoriented) and highly oriented fiber specimens. Nonisothermal treatments also produce some effects on the tensile properties, which may be attributable to the thermal history of samples. Under the conditions of this study, a multistep treatment, ending at a final stage where the temperature was higher than the original melting point of the polymer, did not cause any acceleration in the rate at which tensile properties increase. © 1993 John Wiley & Sons, Inc.
Finite element model and experimental analysis of crack–inclusion interaction
Authors: Li R. , Wu S. , Ivanova E. , Chudnovsky A. , Sehanobish K. , Bosnyak C. P.
Published: April 2003

One of the key requirements for developing tough multiphase blend systems, for example, selecting the type of discrete phases (hard or soft) in a polymer matrix, is the ability to predict the fracture path. Most of these selections rely heavily on prior experience or on intuitive rationale. There are few mathematical guidelines for the materials scientists who are designing new multiphase systems. This article is designed mainly to provide such insight through the development of a theoretical model and through experimental observation. A finite element model has been used to predict the crack velocity and the crack path for a crack that approaches and penetrates a hard or a soft inclusion. A novel experimental approach is then utilized to verify these predictions by introducing hard and soft circular domains in poly(ethylene‐co‐carbon monoxide) specimens by selective photodegradation. © 1993 John Wiley & Sons, Inc.
Optical absorption and thermally stimulated depolarization current studies of nickel chloride‐doped poly(vinyl alcohol) irradiated with low‐level fast neutron doses
Authors: El‐Kader F. H. Abd , Attia G. , Ibrahim S. S.
Published: April 2003

The influence of neutron irradiation on ultraviolet/visible absorption and thermally stimulated depolarization current in nickel chloride–poly(vinyl alcohol) (PVA) cast films has been investigated. The spectral measurements indicate the responsibility of the Ni2+ ion in its octahedral symmetry. Dopant concentrations higher than 10 wt % Ni Cl2 are found to make the samples more resistant to a degradation effect caused by neutron irradiation. The thermally stimulated depolarization currents (TSDC) of pure PVA revealed the existence of the glass transition Tg and space charge relaxation peaks, whereas doped‐PVA samples show a new sub‐Tg relaxation peak. A proposed mechanism is introduced to account for the neutron effects on both glass transition and space charge relaxation peaks. The peak positions, peak currents, and stored charges of the sub‐Tg relaxation peak are strongly affected by both the concentration of the dopant and neutron exposure doses. © 1993 John Wiley & Sons, Inc.
An XPS study of different polyvinylalcohol films' surface composition
Authors: Chihani Thami , Hjertberg Thomas
Published: April 2003

Differences in surface chemical composition were found when examining poly(vinylacetate‐co‐vinylalcohol) (PVOH) film surfaces. The content of the acetate groups increased at the outermost surface when dried in air and similar content, when dried against a glass surface, compared to the bulk content. The enrichment varied from 200–1300%, as compared to the bulk content. The enrichment of the acetate groups was studied with X‐ray photo electron spectrocopy (XPS or ESCA) at different analyzing angles. The bulk content was measured with Nuclear Magnetic Resonance spectrometry (NMR). © 1993 John Wiley & Sons, Inc.
Polymerization studies: The application of differential thermogravimetric analysis
Authors: Popović Ivanka G. , Katsikas Lynne , Weller Horst , Schrötter Susanne , Veliĉkoví Jovan S.
Published: April 2003

The application of differential thermogravimetric analysis (DTGA) to the study of polymerization mechanisms is illustrated using as examples the radical polymerization of di‐n‐alkyl itaconates and methyl methacrylate (MMA). Five poly(di‐n‐alkyl itaconates) were prepared in bulk, both in the presence and absence of n‐dodecyl mercaptan and in solution using AIBN as initiator. The poly(methyl methacrylate) (PMMA) was photoinitiated using colloidal CdS as a photosensitizer. The thermal properties of the resulting polymers are described in terms of the proposed polymerization mechanisms. The advantages and disadvantages of DTGA for the identification of thermally weak structures are discussed. © 1993 John Wiley & Sons, Inc.
Photoluminescence study of β relaxation of polyethylene blends
Authors: Martins‐Franchetti S. M. , Atvars T. D. Z.
Published: April 2003

Secondary β relaxation of polyethylene blends (50/50 HDPE/LDPE) were studied by photoluminescence of anthracene molecules dissolved in the polymer bulk. The temperature of the β relaxation has been determined as Tβ = −40°C by the dependence of the ratio of vibronic components of the fluorescence band on the temperature. The molecular mechanism of this relaxation has been discussed considering the possibility of the energy migration involving anthracene molecules in the singlet electronic excited and ground states. © 1993 John Wiley & Sons, Inc.