bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐vulcanizable rubber blend based on neoprene and carboxylated nitrile rubber: Effect of blend ratio on miscibility and physical properties
Authors: Mukhopadhyay Sujata , De S. K.
Published: April 2003

Mill mixed blend of neoprene and carboxylated nitrile rubber can be vulcanized during molding at high temperatures (180°C) in the absence of any vulcanizing agent, which is supported by FTIR studies. The extent of vulcanization reaction depends not only upon the molding time but also on the blend ratio. Dynamic mechanical analyses and differential scanning calorimeter studies show that neoprene and carboxylated nitrile rubber are not miscible at the segmental level in the self‐vulcanized blend.
SMA polymer thin film electrodeposition on carbon particles
Authors: Desai V. M. , Mahalingam R. , Subramanian R. V.
Published: April 2003

Electrodeposition of styrene‐co‐maleic anhydride (SMA) polymer, as thin films on carbon particle substrates, was carried out in a fluidized electrode bed reactor (FEBR). Feeder current, time of deposition, flow rate of anolyte (i.e., bed expansion or bed porosity), concentration of SMA in the anolyte, and pH of the anolyte were the key parameters investigated. The film characteristics were evaluated through SEM and FTIR analyses, the amounts determined by weighing. The effect of these parameters on the electrodeposition process is discussed and optimum conditions for deposition are proposed. Also, a possible mechanism for electrodeposition, particularly for the SMA–carbon system, is discussed. Furthermore, where relevant, the parameters and mechanism are compared with those for our parallel work on the ethylene‐co‐acrylic acid (EAA)–carbon system.
Processing of poly(amide imides) as matrices for high‐performance composites
Authors: Copeland S. Douglas , Seferis James C. , Carrega Marc
Published: April 2003

Poly(amide imide) (PAI) has proven to be an excellent engineering thermoplastic. Injection and compression molding processes are currently used to produce poly(amide imide) parts when superior toughness, solvent resistance, and high‐temperature heat performance are required. The objective of this work was to determine the essential features necessary to use these systems as matrices for carbon‐fiber‐reinforced composites. The principal steps utilized were: impregnation of the carbon fibers with a PAI solution, drying the solvent from the individual plies, stacking the plies for final consolidation, and a postcure. A processing cycle was developed applicable to resins with different solvent concentration and molecular weight, giving special attention to the solvent evaporation step. A model capable of predicting the rate of evaporation as a function of temperature was developed using the principle of time–temperature superposition. A viscosity model similar to that for a curing thermoset was developed by combining Arrhenius expressions for the temperature and concentration effects. Collectively, this work then provided insight for matrix requirements in the formulation of PAI composites by solvent impregnation.
Application of computed X‐ray tomography scanning in the study of thermo‐oxidative degradation of thick‐walled filled natural rubber vulcanizates
Authors: Lavebratt H. , Östman E. , Persson S. , Stenberg B.
Published: April 2003

The aging of five thick‐walled natural rubber compounds has been studied by computed X‐ray tomography scanning and crosslink density measurements. The compounds were compouded as ordinary carbon‐black‐filled rubbers with sulfur and peroxide as curing agents. The rubber samples were aged in air at 70, 100, and 150°C for 1000h. The relatively new technique of computed X‐ray tomography scanning proved to be a good method for studying the aging procedure, and especially for following the crack propagation in the surface. Antioxidants (TMQ and 6PPD) had a low effect on the resistance toward oxidative degradation and crosslinking under these conditions. Surprisingly, the efficient sulfur‐vul‐canized material had a poor resistance toward thermal degradation. When the crosslink density and the computed X‐ray tomography scanning results were compared, it was assumed that the computed X‐ray tomograph detected oxygen in the surface, both as elementary oxygen and as oxygen in degradation products, i.e., in carbonyls. The results agree well with the theory that oxidative aging is limited by the ability of the oxygen to diffuse into the material.
Photocrosslinking reactions of polyfunctional monomers with vinyl ether or propargyl ether groups
Authors: Nishikubo Tadatomi , Hayashi Yasuyuki , Iizawa Takashi , Sasaki Takashi , Matsumoto Tsuyoshi , Fukudome Toshiyuki
Published: April 2003

Photocrosslinking reactions of di(2‐vinyloxy)ethyl ether of bisphenol‐A (BPAEVE), dipropargyl ether of bisphenol‐A (BPAPE), and diglycidy ether of bisphenol‐A (BPAGE) were carried out using various cationic photoinitiators in 1,2‐dichloroethane. The reaction of BPAEVE occurred with high conversion to give the gel products, and the reaction rate of BPAEVE was higher than that of BPAGE. While, the photocrosslinking reaction of BPAPE did not take place under the same conditions.

Photoinitiated Michael addition reactions of BPAEVE, BPAPE, and other dipropargyl ethers or ester with pentaerythritol (2‐tetramercapto)propionate (PETMP) also proceeded very smoothly to give the gel products by using benzophenone as a photosensitizer in THF. Although the rate of addition reaction of BPAEVE was strongly influenced by the photosensitizer concentration, the addition reaction of BPAEVE with PETMP propagated effectively to give the gel products even without the presence of photosensitizer when irradiated with UV light in THF or toluene solution.
Plasma polymerization of organosiloxanes
Authors: Cai Shide , Fang Jianglin , Yu Xuehai
Published: April 2003

Plasma polymerization of disiloxanes containing various functional groups—hexamethyldisiloxane (HMDSO), tetramethyl‐1,3‐bis(chloromethyl)‐disiloxane (CMDSO), tetramethyl‐1,3‐bis(hydroxylbutyl)‐disiloxane (HBDSO), and tetramethyl‐1,3‐bis(amino propyl)‐disiloxane (APDSO)— was carried out using an inductively coupled electrodeless glow discharge. The monomer polymerization kinetics and the distribution of chemical species deposited showed that monomer reactivity varied among the different siloxanes. Monomers of APDSO and CMDSO possessed higher rates of polymerization. Polymer IR spectra and ESCA analyses indicated that the chemical structures of plasma‐polymerized products of HMDSO, HBDSO, and CMDSO resembled that of crosslinked polydimethylsiloxane. The polar hydroxyl and chlorine functionality in the HBDSO and CMDSO monomers was not present in the deposited films. In contrast, the polymerized product of APDSO retained amino functionality and also formed new Si–H bonds.
Interpenetrating polymer networks: High molecular weight natural rubber and poly(2,6‐dimethyl‐1,4 phenylene oxide)
Authors: De Barros G. G. , Huang M. W. , Frisch H. L.
Published: April 2003

Simultaneous interpenetrating polymer networks (IPNs) of high molecular weight natural rubber (NR) from Manihot glaziovii and poly(2,6‐dimethyl‐1,4 phenylene oxide) were prepared and characterized. A number of pseudo IPNs and blends of these materials were also studied. A single phase morphology is found in full IPNs with either high or low weight percent of NR. The intermediate composition full IPNs, pseudo IPNs, and blends all exhibited microphase separation, as seen by both DSC and SEM studies with domains sizes in the range of 1000–4000 nm. In the discussion we briefly compare these IPNs with the other previously prepared IPNs of poly(2,6‐dimethyl‐1,4‐phenylene oxide).
Surface modification of UHSPE fibers through allylamine plasma deposition. I. Infrared and ESCA study of allylamine plasma formed polymers
Authors: Li Z.‐F. , Netravali A. N.
Published: April 2003

Allylamine (CH2CHCH2NH2) was polymerized through rf generated plasma at varying powers and times. Chemical groups and elemental compositions in the polymers were studied using ESCA and infrared spectroscopy. It was observed that plasma derived polymers contained a significant number of primary amines, along with some secondary and tertiary amines, imines, and nitrile groups. Plasma derived polymers had a complex structure and contained unsaturated groups. A considerable amount of oxygen, primarily from residual air in the plasma reaction chamber, and possibly from atmosphere when plasma polymers were exposed to air, was responsible for carbonyl, amide, ether, and hydroxyl groups found in the polymer structure. Some silicon was also detected in the plasma deposited films.
Effects of poly(vinyl alcohol) suspension medium on critical current density of Ba2Y1Cu3 oxide superconducting filaments produced by suspension spinning method
Authors: Goto Tomoko , Yamada Keisaku
Published: April 2003

Superconducting Ba2Y1Cu3 oxide filament was produced by means of the suspension spinning method. The effects of poly(vinyl alcohol) (PVA) suspension medium on structure and critical current density (Jc) of the filament sintered were explored with PVA of various degrees of polymerization (DP) in dimethyl sufoxide (DMSO), hexamethylphosphoric triamide (HMTA) and the mixed solution of DMSO and HMTA (1 : 1). Although the PVA was removed as a volatile component by heating treatment of the filament, the dispersion behavior of the oxide powder in the filament was dependent on the suspension medium, hence the microstructure and superconducting properties of the filament obtained was affected by the suspension medium. The filament spun through the mixed solution of DMSO and HMTA had a high Jc of 77 K more than 100 A/cm2 at the wide range of DP and powder content. The crystal grains of the oxide in the sintered filament grew finer with increasing the DP of PVA. On the other hand, the Jc of the filament produced by pure solution of DMSO and HMTA was not detected at DP of 3000 and 2450, respectively, due to the influence of entanglement of the molecular chains of PVA.
The effect of chloro‐functional molecules on the ammonia plasma treatment of silicone elastomers
Authors: Gaboury Scott R. , Urban Marek W.
Published: April 2003

Attenuated total reflectance (ATR) FTIR spectroscopy was utilized for surface studies of ammonia/plasma‐modified poly(dimethylsiloxane) (PDMS) elastomer networks containing residual chloro‐functional molecules. Ammonia/plasma modification of PDMS containing chloro‐functional molecules causes the formation of surface amide groups, but due to the parallel formation of surface ammonium chloride, amide groups are not chemically bonded to the PDMS surface. The two primary sources of chlorine‐containing species are residual traces of freon and cross‐linking initiators present in the network. In the absence of chloro‐functional molecules, ammonia/plasma surface modifications of PDMS leads to the formation of stable surface amide groups.
Mechanical and thermal behavior of cotton cellulose grafted with hydroxyethyl methacrylate using photoinitiation
Authors: Shukla S. R. , Rao G. V. Gopala , Athalye A. R.
Published: April 2003

The textile properties of tensile strength and thermal decomposition of cotton cellulose grafted by photoinitiation technique using 2‐hydroxyethyl methacrylate monomer were studied. The photoinitiators, namely, uranyl nitrate (UN) and ceric ammonium nitrate (CAN), were used during grafting of unswollen and swollen cotton samples. The tensile strength decreased with increase in graft add‐on, whereas, the thermal stability was imparted to the grafted cotton according to the level of graft add‐on.
Study of curative interactions in cis‐1,4‐polyisoprene (IR). V. General experimental procedure
Authors: Kruger F. W. H. , McGill W. J.
Published: April 2003

The tetramethylthiuram disulfide (TMTD) and zinc dimethyldithiocarbamate (ZDMC) related vulcanization of cis‐1,4‐polyisoprene (IR) were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and electron spin resonance (ESR). The progress of the reactions in a given compound was monitored by analyzing the vulcanizate at selected points along the DSC curing curve. Full details of the analysis procedures are given. Analysis were mainly concerned with measurement of the crosslink densities, percentage of polysulfidic crosslinks, and the types and quantities of extractable compounds by thin layer chromatography (TLC) and high‐performance liquid chromatography (HPLC).
Study of curative interactions in cis‐1,4‐polyisoprene. VI. Interaction of some combinations of sulfur, tetramethylthiuram disulfide, and ZnO
Authors: Kruger F. W. H. , McGill W. J.
Published: April 2003

The interaction of curatives in the systems cis‐1,4‐polyisoprene (IR)–sulfur, IR–sulfur–ZnO, IR–tetramethylthiuram disulphide (TMTD), and IR–sulfur–TMTD were studied. Thermal events observed in the differential scanning calorimetry curing curves characteristic of these systems were explained in terms of the melting/liquefaction of compounds, the evaporation of gases, and the vulcanization process itself. The similarity of the IR–sulfur and IR–sulfur–ZnO curing curves suggested that sulfur and ZnO were unreactive during vulcanization. On heating the IR–TMTD and IR–sulfur–TMTD systems, gases such as Me2NH and CS2 formed easily. Although the maximum crosslink densities in the latter systems were low, the crosslink formation was found to be strongly exothermic. The sulfur efficiency parameter E was estimated for the IR–sulfur–TMTD system and decreased steeply from 37.5 (at 143.2°C) to 16.6 (at 151.0°C). This was taken as evidence that much of the bound sulfur was initially combined in pendent groups. Then E increased dramatically toward the advanced stages of cure, emphasizing the extraordinary inefficient manner in which sulfur was utilized to form crosslinks.
Structure–property relationships for styrene crosslinked polyesters. I. Network structure and rubbery elastic modulus
Authors: Bellenger V. , Mortaigne B. , Grenier‐Loustalot M. F. , Verdu J.
Published: April 2003

Ten unsaturated polyester prepolymers differing by the nature of the diol, by the maleate/phthalate molar ratio, or by the chain length, were crosslinked by about 40% by weight of styrene and then analyzed by IR spectrophotometry, solid state NMR, and rubbery elasticity measurements.

The spectrometric measurements revealed a practically complete conversion of the styrene/fumarate copolymerization. The rubbery elastic modulus varies in a complex way with the presumed network structure.

A non‐ideality factor f was defined from the current theories; f is a decreasing function of the average number of flexible bonds between crosslinks.

The networks based on dimeric diols display a practically ideal behavior.

The influence of dangling chains, corresponding essentially to polyester chain ends, is taken into account by the Graessley's formula in which trifunctional and tetrafunctional crosslinks are distinguished. A method for the estimation of the nature and weight fraction of dangling chains was proposed.
Physical properties and dyeability of silk fibers modified with ethoxyethylmethacrylate polymer
Authors: Tsukada Masuhiro , Freddi Giuliano , Matsumura Masaaki , Shiozaki Hideki , Kasai Nobutami
Published: April 2003

The structural characteristics, physical properties, and dyeing behavior of Bombyx mori silk fibers containing ethoxyethylmethacrylate (ETMA) polymer are reported in relation to the add‐on. The add‐on value increased with the reaction time and attained a maximum after 60 min at 80°C. The surface of silk fibers with an add‐on value of 40% showed the presence of several irregular granules, consisting of ETMA oligomers. The infrared spectrum of the silk fibers containing the ETMA polymer showed overlapped absorption bands due to the molecular conformation of untreated silk and ETMA polymer, giving evidence that the ETMA polymerization occurred inside the fiber matrix. The DSC results suggested that the thermal decomposition behavior of the silk fiber remained almost unchanged, except that the decomposition temperature shifted slightly to higher temperature. The tensile properties of the silk fiber remained unchanged regardless of the ETMA polymerization. The rate and extent of acid dye uptake was greatly increased by the polymerization of ETMA into the silk fibers as well as the transfer printing properties.
Dynamic light scattering and ultrasonic investigations during the cure reaction of an epoxy resin
Authors: Alig Ingo , Lellinger Dirk , Nancke Katja , Rizos Apostolos , Fytas George
Published: April 2003

Brillouin scattering (BS), photon correlation spectroscopy (PCS), and ultrasonic (US) measurements were conducted to study the curing process of diglycidyl ether of bisphenol A with butane‐1,4‐diol at a curing temperature of 100°C. The experimental techniques probe the primary glass‐rubber transition during the curing reaction. The primary relaxation time τ obtained from the BS and US velocity and absorption increases with curing time and hence the BS experiment measures τ at earlier stages of cure than the US experiment. The relaxation times at a different extent of reaction and for different measuring temperatures are consistent with BS, US, PCS, and DSC measurements and conform to a single reduced Vogel–Fulcher–Hesse–Tamann equation. Furthermore, the US experiments show evidence of secondary relaxations in the epoxy system.
Functional polymers for colloidal applications. I. Structural effects of lipophile‐modified polyacrylates on adsorption and dispersion ability
Authors: Kuo Ping‐Lin , Chang Ta‐Cheng , Lu Li‐Mei
Published: April 2003

Polyacrylic acids of four molecular weights are prepared. A series of poly(methylacrylate‐acrylic acid) copolymers with four specific methylacrylate/acrylic acid ratios and molecular weights has been successfully synthesized from the corresponding polyacrylic acids. These polymers and copolymers are used as dispersants for dispersing TiO2 into aqueous phase. Viscosity, sedimentation, and electron microscopy are used to evaluate their dispersion ability. The extent of adsorption and the zeta potential are measured to evaluate their adsorption behaviors on the surface of TiO2. The viscosity, sedimentation, and electron microscopy results are comparable parallel for showing the dispersing ability of a polymer or a copolymer. The polymer (or copolymer), which results in a lower viscosity, shows a slower sedimentation rate and a more homogeneous distribution of particles in microphotographs. The minimum viscosity needed to disperse TiO2 decreases with the decreasing molecular weight of polyacrylic acid. It was found that partial esterification of polyacrylic acid results in a broader range of minimum viscosity. The trend of the amount adsorbed is similar to that of zeta potential. These two results are used to interpret the viscosity curve.
Kinetics of imidization of poly(amic acid) in miscible and immiscible polymer blends
Authors: Makhija S. M. , Pearce E. M. , Kwei T. K.
Published: April 2003

Blends of commercial poly(amic acid), LARC‐PAA polymer were prepared with thermoplastic polyimide P84. The blends were shown to be miscible over a certain composition range. Chemical imidization of LARC‐PAA in the blends leads to phase separation. Thermal imidization of LARC PAA in the blends was carried out in the solid state. Miscible compositions of the blend remained miscible after imidization and showed a single glass transition for each blend. Immiscible compositions after imidization remained immiscible and showed two glass transition temperatures in the DSC scans. The kinetics of thermal imidization of PAA to polyimide (PI) in the solid state were studied using FTIR. In the immiscible blend the kinetics remained unaffected while in the miscible state the rate of imidization became faster than that of the pure PAA.
Analysis of thermal curves obtained during radiation curing of polymeric films
Authors: Gozzelino G. , Priola A. , Mantegna M.
Published: April 2003

Thermal curves were obtained during the UV curing process of a film containing reactive oligomers by monitoring in “real time” the temperature of the film surface by means of a high sensitive thermocouple. The system can be reproduced by a mathematical model that allows one, in welldefined conditions, to obtain the thermal curve of the system when the physical parameters of the materials, the polymerization enthalpy, and the kinetics of the double bond conversion are known. By using the kinetic data obtained through real time FTIR analysis, the model allows one to obtain the theoretical thermal curve of the system. The agreement between this curve and that obtained experimentally was found satisfactory, thus confirming the validity of the model proposed. The possible applications of the method are discussed.
Crosslinking of poly(vinyl chloride) with bismaleic compound. I. Crosslinking mechanism
Authors: Chen Minwei , Zhou Dafei
Published: April 2003

Crosslinked poly(vinyl chloride) (PVC) was obtained by using bismaleic compound (BMC). Styrene, as auxiliary crosslinker, can markedly promote the crosslinking course. After having carefully studied the gelling behavior of PVC in crosslinking, and the reactivity of styrene and BMC with PVC, the crosslink mechanism was suggested. The main crosslink reaction is the bridging of bismaleic compound between PVC macroradicals, which were created by thermal degradation of PVC and disproportionation of PVC with initiator radicals and styrene radicals. The first step of crosslink reaction was the BMC grafting on PVC macroradicals. Then styrene copolymerizes with active center bearing on bismaleic compound to propagate graft chain, which make bridging reaction easier to take place. At last, PVC* reacted with another double bond possessed by grafted BMC to form network structure
The introduction of alkyl, ester, carboxylate, amino, hydroxyl, and phosphate functional groups to the surface of polyethylene
Authors: Bentjen Susan B. , Nelson David A. , Tarasevich Barbara J. , Rieke Peter C.
Published: April 2003

The surface of polyethylene was derivatized with ester, carboxylate, amino, hydroxyl, and phosphate functional groups. α, ω bifunctional alkanes, containing on one end a primary amine, were coupled to oxidized polyethylene through an amide linkage. Polyethylene was first oxidized with chromic acid, the carboxylate groups were converted to the acyl chloride with phosphorus pentachloride, and then reacted with a primary amine to give the covalently bound amide. The copposing ends of the bifunctional alkanes were the methyl, tertiary amine, ester, and hydroxyl groups. The ester was converted to the carboxylate by acid cleavage and the hydroxyl group converted to the phosphate by treatment first with phosphorus oxychloride and then aqueous base. Attenuated total reflection FTIR, XPS, and pH‐dependent contact angle wetting were used to characterize the surfaces. The FTIR data were used to confirm the formation of the amide and to detect an undesired carboxylate/ammonium ion complex formed in the presence of trace amounts of water. XPS data were used to confirm expected changes in elemental composition and to provide quantitative estimates of the yields. Oxidation of the polyethylene introduced 5 × 1014 carboxylate groups/cm2 in the 25 Å XPS sampling depth. Of these, up to 98% could be converted to the amide. The advancing contact angle data confirmed the acid/base behavior of the functional groups.
Compression creep of molten low‐density polyethylene
Authors: Aleman J. V.
Published: April 2003

Viscoelastic parameters of low‐density polyethylene melt (LDPE) in compression creep have been measured. Volume deformation (k%) increases as pressure (P) increases and temperature (T) decreases. Plots of the bulk creep compliance B(t) vs. time (t) may be shifted to provide master curves. As the pressure and the temperature increase, the pressure shift factors (bp and ap) increase almost linearly [activation volumes (ΔV*) varying from 1.0 to 15.0 cm3 mol], while the temperature‐shift factors (bT and aT) decrease. The steady‐state creep compliance (Bs) describes the recoverable storage of elastic energy (Be) and seems to be related to the extrusion die‐swell (Bsc/Bsd). Volume viscosity (ηK) decreases with increasing stress (P) and increasing temperature (T).
Solute migration through polypropylene blend films
Authors: Jenke Dennis R.
Published: April 2003

The migration of several low molecular weight model solutes through a polypropylene/polyolefin blend was examined via a permeation‐cell experimental design. Diffusion coefficients and permeation rates are obtained for the model solutes. The permeation rates exhibit Arrenhius‐type behavior. A bimodal permeation model is proposed wherein the permeation rate is correlated with the linear combination of a solute's Permicor constant and solute/polymer equilibrium interaction constant. The model effectively predicts the behavior of the polymer and solutes studied. The implication of the observed behavior to container compatibility assessment is discussed.
Permeation of binary–liquid mixtures through elastomers
Authors: Vahdat Nader , Taylor Henry , Alsayegh Ali
Published: April 2003

Permeation of binary liquid mixtures through two commercially available elastomers were examined. The four systems studied are benzene–cyclohexane/neoprene, toluene–n‐hexane/neoprene, toluene–methanol/nitrile, and toluene–o‐xylene/nitrile. Permeation rate–time curves for several mixture compositions were prepared for each system. In the first three systems, the difference in the plasticizing effect of the two liquids on the membrane was very large. The liquid with the smaller plasticizing effect showed a permeation enhancement and the liquid with the larger plasticizing effect experienced a permeation depression. Toluene–o‐xylene/nitrile represented a system in which the two liquids plasticized the membrane at almost the same rate. This system showed a permeation depression for both liquids.
Studies on curing urethane prepolymers with aniline–formaldehyde resins
Authors: Kozakiewicz Janusz , Orzechowski Andrzej , Raszczuk Alina , Jamróz Michai H. , Dobrowolski Jan Cz.
Published: April 2003

Commercial aniline–cresol–formaldehyde resin, two model aniline–formaldehyde and aniline–cresol–formaldehyde resins, and methylenedianiline have been used as curatives for NCO‐terminated urethane prepolymer prepared from polyoxypropylenediol and toluene‐diisocyanate. Based on viscoelastic behavior of the investigated systems and changes in their IR spectra, it has been concluded that phenolic OH groups present in aniline–cresol–formaldehyde resin do not play an important role in the curing process carried out at RT despite earlier suggestions to the contrary. The explanation for specific behavior of systems where urethane prepolymers have been cured with commercial aniline–cresol–formaldehyde resin is presumably the presence of small amount of solvent (benzyl alcohol) in that resin, which may influence the reaction kinetics.
Ablation of poly(2‐hydroxyethyl methacrylate) by 193‐nm excimer laser radiation
Authors: Chirila Traian V. , Van Saarloos Paul P.
Published: April 2003

Data on the ablation of poly(2‐hydroxyethyl methacrylate) (PHEMA) by 193‐nm radiation pulses, produced by an ArF excimer laser, are presented for the first time and are compared with the data for poly(methyl methacrylate) (PMMA). The ablation rate of PHEMA is lower than that of PMMA and some possible explanations are advanced. The other features of the etch curves are similar and confirm a predicted ablative behavior of the addition polymers susceptible to depolymerization. Geometric aspects of the ablated polymer's surface, and the influence of inhomogeneities in the material, are also presented and discussed.
Polymerization of olefins through heterogeneous catalysis X: Modeling of particle growth and morphology
Authors: Hutchinson R. A. , Chen C. M. , Ray W. H.
Published: April 2003

The development of a detailed model describing particle growth in olefin copolymerization systems is presented. The Multigrain Model considers in detail monomer sorption, mass transfer, and changing porosity within the growing particle, as well as heat and mass transfer across the external film of the particle. The model predicts catalyst performance, including polymerization rates and particle morphology, in different reactor media without parameter adjustment. Internal void fractions are calculated through an examination of the relative growth rates within the growing particle. The model is used to examine the effects of mass transfer limitations, prepolymerization, and nonuniform metal distribution on the particle growth process. Model predictions of morphology show the same trends as observed experimentally.
Plasma modification of cellulose derivatives as biomaterials
Authors: Poncin‐Epaillard Fabienne , Legeay Gilbert , Brosse Jean‐Claude
Published: April 2003

A film of cellulose acetate was submitted to a cold plasma of tetrafluoromethane or of sulfur hexafluoride. The interactions of these cold plasmas and cellulose acetate lead to a material whose surface has been modified by fluorination. Comparison of CF4 or SF6 plasma treatment shows that fluorine atoms provided by each kind of plasma induce degradation and grafting of fluorocarbon radicals on the surface. As a consequence, the surface energy decreases and offers the possibility of a better response of plasma‐modified cellulose derivatives used as biomaterials (e.g. hemodialysis membrane).
Study on organosilicon positive resist. III. Organosilicon positive excimer laser resist (OSPR‐2016)
Authors: Sugiyama Hisashi , Mizushima Akiko , Nate Kazuo
Published: April 2003

A new alkali‐developable organosilicon positive excimer laser (KrF) resist (OSPR‐2016) has been developed for a bilayer resist system. OSPR‐2016 is composed of poly(p‐hydroxybenzylsilsesquioxane) and methyl cholate‐tris (α‐diazoacetoacetate). The ratio is 72.5 : 27.5 w/w. A sample of 0.5‐μ thick OSPR‐2016 resolved 0.35 μ L&S patterns when exposed to a dose of 320 mJ/cm2 from an excimer laser projection printer (NA = 0.37).
Epoxy resins based on aromatic glycidylamines. V. Shelf life of TGDDM‐based epoxy resins
Authors: Podzimek Š. , Dobáš I. , Kubín M.
Published: April 2003

The effect of aging on resin composition was investigated as a part of a study concerned with the evaluation of epoxies containing N, N, N′, N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM). Long‐term stability of three different epoxy resins based on TGDDM and their mixtures with 4,4′‐diaminodiphenylsulfone (DDS) was followed at 23 ± 2°C at a relative humidity ranging from 45% to 55%, by means of GPC and HPLC; short‐term stability of the resins was evaluated at 125°C.
Swelling characteristics of polymer membranes in the presence of aromatic hydrocarbon liquids
Authors: Harogoppad S. B. , Aminabhavi T. M. , Balundgi R. H.
Published: April 2003

Swelling properties of some engineering polymer membranes in the presence of monocyclic aromatic hydrocarbons have been studied from the solvent immersion experiments. The liquids were chosen with varying methyl and methoxy substitutions to study the effect of substitutions on their transport properties. Diffusion coefficients have been extracted from the swelling results. The concentration dependence of diffusion coefficients has been investigated. Furthermore, the swelling and diffusion results have been used to assess the suitability of the polymer membranes in environments containing aromatic hydrocarbon liquids.
Concentration‐dependent diffusion of dye in reactive dyeing systems
Authors: Lin S. H.
Published: April 2003

The physical model of the reactive dyeing system proposed by Sada et al. is extended in this communication to the case with a conentration‐dependent diffusion coefficient of dye. The present model with an exponential concentration dependence of the diffusion coefficient is shown to predict the observed data better than did the previous one with a constant diffusion coefficient. Effects of the concentration dependence of the diffusion coefficient, dye reaction rate, degree of mixing, and volume ratio of fiber substrate to the dyebath on the rate of fractional fiber fixation and the dye concentration in the dyebath are investigated parametrically. It has been found that the effect of the volume ratio of the fiber substrate to the dyebath on the fractional fiber fixation is not of the same order of magnitude as those of the other three factors.
Preparation and characterization of high molecular weight poly(hydroxy ethers) with unusually high glass transition temperatures
Authors: Silvis H. Craig , White Jerry E. , Crain Steven P.
Published: April 2003

A series of novel poly(hydroxy ethers) have been prepared via polymerization of the diglycidyl ethers of bisphenol‐A (4), 4,4 ′‐tribromotetramethylbiphenol (6a), and 4,4 ′‐tetrabromotetramethylbiphenol (6b) with a variety of rigid diols in an effort to systematically modify structural features of the phenoxy repeat unit in order to control the torsional mobility of polymer backbones and produce materials with softening temperatures higher than are typical for the class. The resulting poly(hydroxy ethers) displyed glass transition temperatures ranging from 109 to 242°C. There of the polymers were characterized with respect to tensile and impact properties and were compared to the polymer sythesized from bisphenol‐A (1) and bisphenol‐A diglycidyl ether (4).
Multiobjective dynamic optimization of batch free radical polymerization process catalyzed by mixed initiator systems
Authors: Butala D. N. , Liang W. R. , Choi K. Y.
Published: April 2003

The optimal control policies for batch free radical polymerization of styrene catalyzed by a binary mixture of monofunctional initiators have been determined using a multiobjective dynamic optimization technique. The process objectives considered in the optimization include monomer conversion, polymer molecular weight, initiator residue level, and total reaction time. It is illustrated through model simulations and experiments that the performance of the batch polymerization process can be improved significantly through the use of optimal initiator mixture and polymerization temperature programming. This paper also illustrates how the multiobjection optimization technique can be used effectively to solve complex polymerization reactor optimization problems with detailed reaction models.
Copolyimides using 3‐phenyl tricyclo [6,2,2,02,7] dodeca‐2,11‐ene‐5,6,9,10‐tetracarboxylic dianhydride as a thermosetting functional group: Preparation, characterization, and thermal curing chemistry
Authors: Su Ching‐Yie , Lee Yu‐Der
Published: April 2003

Copolyimides were prepared by the reaction of 4,4‐oxydianiline (ODA) with two dianhydrides, namely, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) and 3‐phenyl tricyclo [6,2,2,02,7] dodeca‐2,11‐ene‐5,6,9,10‐tetracarboxylic dianhydride (PTDDA). ODA and BTDA first reacted in DMAc solvent, then following the addition of PTDDA, which was used as a thermosetting functional group in the polymer's backbone. Two homopolyimides prepared from the reaction of ODA with BTDA or PTDDA were also synthesized. The properties of homopolyimides such as solubility, thermal properties, and thermal curing mechanism were compared to those of copolyimides. The results showed that the tricyclic structure of the PTDDA unit underwent a reverse Diels‐Alder reaction at near 300°C and it controlled the thermal behaviors of copolyimides.
Organotin polymers. XV. Azeotropy in terpolymerization reactions of tributyltin acrylate or methacrylate with itaconic acid or dimethylitaconate and acrylonitrile
Authors: Mahmoud A. A. , Shaaban A. F. , Azab M. M. , Messiha N. N.
Published: April 2003

Ternary copolymerization of tri‐n‐butyltin acrylate (TBTA) or methylacrylate (TBTMA) with itaconic acid (IA) or dimethyl itaconate (DMI) and acrylonitrile (AN) were carried out in solution at 70°C in the presence of a free radical initiator. Experimental terpolymerization data agreed well with calculations based on the Alfrey‐Goldfinger equation. Ternary azeotropic compositions for TBTA‐IA‐AN, TBTMA‐IA‐IA, and TBTMA‐DMI‐AN systems were 39.0 : 26.1 : 34.9, 51.7 : 10.5 :37.8, and 00.3 : 66.3 : 33.4 mol %, respectively. Also, “pseudo‐azeotropic” regions were indentified where the deviation between feed and polymer compositions is very small.
Cathodically electrodepositable novel coating system from castor oil
Authors: Rao J. Laxmikanth , Balakrishna R. S. , Shirsalkar M. M.
Published: April 2003

A novel polyol synthesised from castor oil by aminolysis and a partially blocked toluene–diisocyanate blocked with N,N′‐diethyl lactamide was used to prepare an urethane. This was used in different weight proportions to modify epoxy amine adduct to give binders suitable for cathodic electrodeposition. The pigmented composition of these binders based on the iron oxide (natural) and titanium dioxide (rutile) gave coatings with improved performance.
Synthesis and structure–property relationships of a new class of rubber‐toughened PMMA
Authors: Laurienzo P. , Malinconico M. , Martuscelli E. , Ragosta G. , Volpe M. G.
Published: April 2003

In the present work, blends between poly(methyl methacrylate) (PMMA) and poly(ethylene‐co‐vinyl acetate) (EVA) rubbers obtained by in situ polymerization of the acrylic monomer in the presence of the rubber have been investigated by linear elastic fracture mechanics (LEFM), by Charpy impact tests, and by scanning electron microscopy (SEM). Particularly, a correlation among molecular weight and composition of the EVA rubbers, phase structure development, and, consequently, mechanical impact properties of the resulting blends has been drawn.
On the deformational characteristics of porous polymeric tubes
Authors: Islam M. A. , Malamusis S. , Mladenov I.
Published: April 2003

The deformational behavior of the porous polymeric tube in the operational period has been studied. The tubes are prepared from a polymeric composition consisting of low‐density polyethylene and vulcanized rubber particles. It is established that during operation the tubes undergo only radial elastic deformation. A threshold pressure is necessary to initiate the radial deformation. At a constant pressure, the radial deformation increases with an increase in the polyethylene content in the tube material. The stress necessary to break the tubes during operation is much lower than the tensile strength.
Plasma polymerization of allylamine/3‐aminopropyltriethoxysilane mixtures: Surface nitrogen control
Authors: Barbarossa Vincenzo , Contarini Salvatore , Zanobi Antonio
Published: April 2003

A study has been conducted to determine the effects of gas‐feed composition and RF power on the deposition rate and on the surface nitrogen content of thin films produced by plasma polymerization of allylamine/3‐amino‐propyltriethoxysilane (AA/3‐APTS) mixtures. It has been found that while the deposition rate decreases slightly by increasing the AA content in the mixture, the surface nitrogen content, determined by XPS as N : Si molar ratios, increases up to a value of 8 : 1. Moreover, the nitrogen increase is not linear with the AA concentration and a maximum in the N/Si values is found for AA/APTS ratios close to 3 : 1, at all RF powers. The discussion on the polymerization mechanism for the mixture is based on evaluating and combining the behavior of each component, when plasma‐polymerized alone in similar conditions.
Studies of functionalized polystyrene–poly(2, 6‐diphenyl‐1,4‐phenylene oxide) blends
Authors: Hseih D. T. , Peiffer D. G.
Published: April 2003

The phase behavior of an immiscible binary component blend and its functionalized analogs were studied. The unfunctionalized blends are composed of polystyrene and poly(2,6‐diphenyl‐1,4‐phenylene oxide), whereas the functionalized versions contain a relatively broad range of ionic content, i.e., sodium sulfonate units. Extensive glass transition (Tg) measurements show that these blends are immiscible over a broad ionic content and molecular weight range. This phenomenon, however, does not inhibit these blends from possessing improved mechanical properties since the associating‐type ionic interactions can effectively bridge the two phases. These results are in contrast with blends composed of unfunctionalized but miscible components. In this case, miscibility and immiscibility can be tailored through the precise control of the level of functionalization of one or both components of the blend.
Stereoselective modification of poly(vinyl chloride) in a twin screw extruder
Authors: Mijangos C. , Cassagnau P. , Michel A.
Published: April 2003

Continuous chemical modification of poly(vinyl chloride) (PVC) with sodium benzene thiolate (NaBT) in a counter‐rotating twin screw extruder has been studied. The course of the reaction is analyzed, taking into account the physical changes of the polymer along the length of the screw. From the results, it is concluded that the modification reaction is associated with the fusion–gelation process. The reaction kinetics are determined as a function of the mean residence time with the aid of a UV tracer. Temperature profile, flow rate, and premixing are some of the processing parameters influencing the reaction, kinetics. The continuous modified polymer is analyzed in terms of thermal behavior, molecular weight, and stereochemical structure, and the results are compared with those obtained by a discontinuous melt process (Haake–Rheocord). It is confirmed that the same stereoselective substitution mechanism occurs as that in discontinuous melt with no side reactions.
Phase equilibria of modified ethylene glycol–maleic anhydride–phtalic anhydride polyester resins
Authors: Hyršl Jan , Podzimek Štěpán , Eichler Josef
Published: April 2003

This paper describes the influence of a termination of ended carboxyl groups of ethylene glycol–maleic anhydride–phtalic anhydride polyesters with cyclohexanole on a position of phase interface of the unsaturated polyester–styrene system. At given temperatures, optimal molecular weights were determined for the achievement of maximal miscibility of this polymer with styrene. Simultaneously, a model implicit equation was proposed, which is based on the assumption that the dependence of the interaction parameter χ on number‐average molecular weights is similar to that dependence of the interaction parameter χ on temperature. Solution of these implicit equation are isotherms in the phase diagram Mn−ϕ2−Tcloude point.
Crystal size and distortion parameter of natural pure mysore silk fibers (Bombyx Mori)
Authors: Somashekar R. , Urs R. Gopalkrishna , Madhava M. S.
Published: April 2003

Crystal size and lattice distortion parameters were determined experimentally by recording X‐ray diffraction patterns of natural silk fiber (pure Mysore silk, Bombyx Mori) using Fourier cosine coefficients of the intensity profile of an X‐ray (210) reflection. Also, the crystal size distribution along [210] direction is given.
Effect of methanol on optical property of irradiated poly(methyl methacrylate)
Authors: Lin C. B. , Lee Sanboh
Published: April 2003

The effect of methanol on optical property of irradiated poly(methyl methacrylate) (PMMA) has been investigated. The gamma irradiation enhances the methanol transport in PMMA. The activation energies of diffusivity for case I and velocity for case II decreases with increasing gamma ray dose. For the same wavelength, in the range 350–800 nm, the transmittance decreases with increasig gamma ray dose. The equation of transmittance I with gamma ray dose ϕ at the wavelength 405 nm is I = I0 exp(−0.06ϕ1/2), where I0 is the transmittance of virgin PMMA. When the irradiated PMMA is immersed into methanol bath, the yellow color fades out gradually. The recovery of transmittance increases with methanol content in irradiated PMMA. The boundary to separate the outer region (solvent affected zone) from the inner region (no solvent‐affected zone) is also studied. The rate of boundary movement increases with gamma ray dose.
Diffusion of water into a photopolymer film
Authors: Best Margaret Evans , Moylan Christopher R.
Published: April 2003

Sorption of water vapor into thin films of a crosslinked dimethacrylate UV‐cured polymer was measured by means of a quartz crystal microbalance apparatus. The diffusion coefficient and solubility were obtained. An upper limit to the water vapor diffusion coefficient, namely, the diffusion coefficient for liquid water in intimate contact with the sample, was measured for reference purposes by both gravimetric and infrared spectral techniques. A water uptake value for thick films was obtained gravimetrically as a reference for the thin film value. Measurement of the diffusion coefficient allows the determination of the length of time that the photopolymer could act as an effective water vapor barrier.
Application of poly(butadiene‐co‐acrylic acid)–sucrose as gel in the separation of different substances
Authors: Alvarez C. , Bertorello H. , Strumia M.
Published: April 2003

The synthesis of a new hydrophobic gel by reacting cooligomer of butadiene and acrylic acid (Mw 4500) with sucrose crosslinking in best conditions is described. Application of this new gel swelled in different organic solvents is studied. Separation of organic substances in benzene was achieved with higher retention of more polar substances. By this way, cholesterol was separated from lecithin, acrylic acid from polybutadiene with terminal carboxylic groups, and metals such as copper from organic solvents.
Effect of barbituric acid on the self‐polymerization reaction of bismaleimides
Authors: Pan Jing‐Pin , Shiau Gwo‐Yuh , Lin Song‐Shiang , Chen Ker‐Ming
Published: April 2003

Barbituric acid (BTA) was used as an initiator for the homopolymerization of bismaleimide (BMI). The reaction was controlled by the amount of barbituric acid and ended up with solvent‐soluble oligomers. The effects of varying the amounts of BTA, as well as the reaction time, on BMI's self‐polymerization reaction were investigated. The thus‐formed oligomers were characterized by gel permeation chromatography (GPC), infrared spectra (IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The degree of reaction increased proportionally to the concentration of BTA or the length of the reaction time. Thus, solvent‐soluble BMI oligomer can be controlled and obtained.
Development of potentially degradable materials for marine applications. III. Polyethylene‐polyethylene oxide blends
Authors: Gonsalves K. E. , Patel S. H. , Trivedi D. H.
Published: April 2003

The effect of a simulated marine environment on unstabilized polyethylene‐polyethylene oxide blends, having varying polyethylene oxide content (up to 40% by weight), with or without a metal catalyst (e.g., cobalt (III) acetylacetonate) and a metal containing plasticizer (e.g., aluminum stearate), has been studied for 10 weeks exposure time. In the absence of metal catalyst and plasticizer, phase separation of polyethylene oxide was quite evident visually after melt mixing and subsequent regular compression molding of polyethylene‐polyethylene oxide blends. However, these blends rendered better and uniform mixing in the presence of metal catalyst and plasticizer. Since polyethylene oxide is a water soluble component of the system, % weight loss increased significantly with increase in its content after exposure to brine. These blends have been further characterized by tensile properties, optical and scanning electron microscopy, and thermal analysis in order to monitor mechanical as well as morphological changes.
Creep of polycarbonate: Experiments and correlation with relaxation
Authors: Malkin Alexander Ya. , Teishev Albert E. , Kutsenko Michael A.
Published: April 2003

The correctness and reliability of different methods of creep function calculations from relaxation curves were investigated by the computational experiment method. It was shown that an adequate description of some initial (relaxation) curve was not sufficient for the correct determination of the proper creep function. The best results can be achieved by the method of expansion of a relaxation curve into the discrete sum of exponents; some other procedures of analytical approximation of relaxation curves can lead to considerable unexpected errors in calculated creep functions.

The experiments were done with polycarbonate (PC) in the linear stress range and also at high stresses. The limits of linear viscoelastic behavior were determined.