bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the anomalous particles formed during the surfactant‐free emulsion polymerization of styrene
Authors: Cox R. A. , Wilkinson M. C. , Creasey J. M. , Goodall A. R. , Hearn J. 
Published: April 2003

AbstractThe presence of anomalous regions within polystyrene latex particles prepared in the absence of added emulsifier has been investigated. It appears that they arise through loss of monomer from particles consisting of a discrete monomer‐rich region surrounded by a polymer shell. It is likely that in most cases, monomer is lost from the region on evacuation prior to electron microscope examination, although there is some evidence from γ‐irradiated samples (prior to electron microscopy) that loss of monomer can also occur during storage and/or dilution of the sample. Scanning electron microscopy and carbon replication techniques have been used to determine the shapes of the voids. Gas adsorption studies and carbon replication have also served to illustrate that the presence of the regions was not due to electron‐beam damage. The presence of extrusions on some samples has been attributed to incomplete loss of monomer on evacuation due to the thickness of the surrounding polymer shell.
ESCA applied to polymers. XV. RF Glow‐discharge modification of polymers, studied by means of ESCA in terms of a direct and radiative energy‐transfer model
Authors: Clark D. T. , Dilks A. 
Published: April 2003

AbstractThe crosslinking of an ethylene–;tetrafluoroethylene copolymer by exposure to an argon plasma, excited by an inductively coupled RF field, is studied over a wide range of pressures and power loadings. The results are interpreted in terms of a two‐component, direct and radiative energy‐transfer model showing that the outermost monolayer crosslinks rapidly via direct energy transfer from argon ions and metastables.
Copolymerization reactivities and conductivities of some living polymers of p‐substituted styrenes
Authors: Favier J. C. , Sigwalt P. , Fontanille M. 
Published: April 2003

AbstractA kinetic study in tetrahydrofuran of the addition of 1,1‐diphenylethylene on para‐substituted styrylcarbanions (with Cs+ as counterion) has given the reactivities of free ions and ion‐pairs. For both species, the addition rate constant increased in the following sequence for the substituent of the phenyl ring: pH < p‐CH3 <p‐CH3O. It was also shown that in the same solvent, the dissociation constants of the polystyryl ion‐pairs decreased with the electron‐donating power of the substituent.
Analysis of degradation products by thermal volatilization analysis at subambient temperatures
Authors: McNeill I. C. , Ackerman L. , Gupta S. N. , Zulfiqar M. , Zulfiqar S. 
Published: April 2003

AbstractIn the subambient thermal volatilization analysis (TVA) technique, degradation products initially at −196°C are allowed to warm up to ambient temperature in a controlled manner under vacuum conditions, and volatilization from the sample tube to a trap at −196°C is monitored by means of a Pirani gauge. The technique is discussed in relation to earlier TVA work in which volatilization from a heated polymer sample was followed. Design and operation of a subambient TVA system are described, and examples of the application of the technique to the study of the degradation products of seven polymers are considered.
Some aspects of plasma polymerization of fluorine‐containing organic compounds
Authors: Yasuda H. , Hsu T. S. 
Published: April 2003

AbstractThe polymerization of perfluorocarbons and fluorohydrocarbons was investigated by using both continuous and pulsed rf discharge (100 μsec on and 900 μsec off). Plasma polymerization of perfluorocarbons is generally slower than that of hydrocarbons, which seems to be due to the absence of contribution of fluorine detachment to the plasma polymerization. Presence of multiple bond(s) or cyclic structure in a monomer is necessary to obtain high enough polymerization; however, the plasma polymerization mechanism postulated to plasma polymerization of hydrocarbons is still valid to these monomers. Cyclic structure is very effective to enhance the plasma polymerization capability of perfluorocarbons. Saturated straight‐chain perfluorocarbons do not polymerize well in plasma, but the grafting of fluorine‐containing functions on the surface of polymeric substrate can be achieved by the plasma of these compounds. The effect of pulse on the plasma polymerization was found to be similar to that found for hydrocarbons.
Investigations on poly(vinyl chloride). IV. Effects of metal chlorides on the thermal decomposition of poly(vinyl chloride)
Authors: Iida Takeo , Gotō Kunio 
Published: April 2003

AbstractThe effects of various metal oxides upon the thermal decomposition of poly(vinyl chloride) (PVC) were previously reported. In this work, 23 metal chlorides were investigated to determine their effects on the thermal decomposition of PVC by pyrolysis–gas chromatography at 500°C. Each metal chloride exhibits influences on the course of thermal decomposition of PVC almost similar to the corresponding metal oxide except for a few elements; the metal chlorides from acidic metal oxides accelerate the thermal decomposition of PVC, but the metal chlorides from basic metal oxides do not. On comparing the effects of metal oxides and metal chlorides on the thermal decomposition of PVC, most metal chlorides were found to accelerate the thermal decomposition of PVC more than the corresponding metal oxides, owing to ease of addition of the chlorine atoms released from metal chloride to the dehydrochlorinated chains. It is concluded from these results that the thermal decomposition of PVC containing metal salts is markedly influenced by the ease with which chlorine atoms are released from the corresponding metal chloride.
Reactivity and flammability of conjugated acetylenes
Authors: White D. M. , Quinn C. B. 
Published: April 2003

AbstractThe thermal reactivities of model phenyleneacetylenes and diacetylenes and of poly(butadiynylene‐1,3‐phenylene) have been examined by differential scanning calorimetry and compared with the oxygen indices of the materials. No direct relationship was found between the heat of reaction and the oxygen index in these compounds. However, the heat of reaction, in general, does decrease with increasing molecular weight and is lower for rigid linear molecules than for related angular structures. These observations appear to be due to a lack of solid‐state reactivity in the crystalline phase and retardation in the melt due to viscosity effects related to molecular size and rigidity. The synthesis of model compounds is described.
Aromatic polyether, ‐ketone, ‐sulfones as laminating resins. XI. Polymers derived from 2,2′‐diiododiphenyl‐4,4′‐dicarboxylic acid
Authors: Banihashemi Ahmad , Marvel C. S. 
Published: April 2003

AbstractAromatic polyether‐keto‐sulfone polymers and related model compounds have been synthesized from 2,2′‐diiododiphenyl‐4,4′‐dicarboxylic acid and a variety of intermediates. It was hoped to convert them to 2,2′‐diphenylethynyl derivatives which could be cured by rearrangement to give dibenzanthracene units in the chain. Low solubilities and high melting points of the products prevented their use in the desired manner.
Aromatic polyether, ‐ketone, ‐sulfones as laminating resins. XII. Derivatives of 2,2′‐diphenylethynyldiphenyl which cure by an intramolecular cyclization
Authors: Banihashemi Ahmad , Marvel C. S. 
Published: April 2003

AbstractPolymers made from 2,2′‐diiododiphenyl‐4,4′‐dicarbonyl dichloride, diphenyl ether, and isophthaloyl chloride have been made and converted to the 2,2′‐diphenylethynyl derivatives. Introduction of units of isophthaloyl chloride reduced the melting point of these polymers to about 200°C, and they could then be cured by heating. A good glass laminate was prepared and cured from one of the polymers.
Polymerization of aromatic nuclei. XVII. Catalytic hydrogenation of poly(p‐phenylene)
Authors: Durham Judith E. , Kovacic Peter 
Published: April 2003

AbstractHydrogenation of poly(p‐phenylene) (I) in cyclohexane at high temperature and pressure with rhodium catalyst gave, in low yield, oligomers of 1,4‐cyclohexylene(II) in the range of 2–16 cyclohexyl units per chain. Apparently only the low molecular weight fraction in I is reduced because of extreme insolubility. II, which appears to be a novel class, was characterized by molecular weight, 1H‐NMR, 13C‐NMR, and infrared spectra, gas chromatography, and microanalyses. Dicyclohexyl and perhydro‐p‐sexiphenyl served as model compounds for comparison in characterization of II.
Some aspects of plasma copolymerization of acetylene with N2 and/or water
Authors: Yasuda H. , Hirotsu Toshihiro 
Published: April 2003

AbstractPlasma polymerizations of mixture of acetylene‐N2, acetylene‐H2O, were investigated by using an electrodeless glow discharge from a 13.5‐MHz radiofrequency source. Properties of plasma polymers were examined as functions of mole ratios of N2 and/or H2O to acetylene. The concentration of trapped free radicals and the internal stress in a plasma polymer decreased as the mole ratio of N2 or H2O increased. Water showed the most pronounced effects in those properties at the mole ratio of 0.3. Gas permeabilities increased by the copolymerization of N2 and/or H2O. Surface energies were also investigated by analysis of contact angles of liquids. Copolymerization of N2 caused a remarkable increase in polar contribution of surface energy. Some fundamental aspects of flow‐rate pressure relationship of mixed gases are presented.
Studies of accelerated sulfur vulcanization of styrene–butadiene rubber by N‐cyclohexylbenzothiazol‐2‐sulfenamide in the presence and absence of dicumyl peroxide
Authors: Ghosh A. K. , Das C. K. , Banerjee S. 
Published: April 2003

AbstractThis study embodies the results and discussion of a comprehensive and systematic investigation of the mechanism of sulfuration of styrene–butadiene rubber accelerated by N‐cyclohexylbenzothiazole‐2‐sulfenamide (CBS) with and without activators. Dicumyl peroxide (DCP) has been taken as a chemical aid to distinguish between free‐radical and polar mechanisms of sulfuration. The rate constant for DCP decomposition in presence of CBS and the reduction in crosslink density by CBS have also been studied. With a constant amount of DCP and sulfur the crosslink density increases with increasing CBS concentration. In the presence of ZnO and stearic acid, crosslinking proceeds faster than in a similar system without these ingredients, and with DCP the crosslinks are found to be formed nearly additively as confirmed by methyl iodide treatment of the vulcanizates. In the absence of DCP, the crosslinking is characterized by an induction period, even in presence of ZnO and stearic acid. In the presence of sulfur, the 2‐mercaptobenzothiazole (MSH) or amine or amine salt form crosslinkins by ionic reaction.
Cationic polymerization with boron halides. IV. Elucidation and control of initiation and termination by the help of model experiments
Authors: Kennedy J. P. , Huang S. Y. , Feinberg S. C. 
Published: April 2003

AbstractThe proposition that BCl3‐coinitiated olefin (isobutylene, styrene) polymerizations terminate by chlorination has been corroborated by model experiments. Key experiments showed that under simulated polymerization conditions neither tert‐butyl chloride nor 2‐chloro‐2,4,4‐trimethylpentane reacts with BCl3; that H2O/BCl3 + 2,4,4‐trimethyl‐1‐pentene (TMP) produce 2‐chloro‐2,4,4‐trimethylpentane; and that H2O/BCl3 + isobutylene gives rise to tert‐butyl chloride. Extended model studies demonstrated that certain alkyl and benzyl chlorides produce carbenium ions in the presence of BCl3 and that TMP can readily be alkenylated by using 1‐substituted allyl chlorides in conjunction with BCl3. These experiments led to the discovery that olefin polymerizations may be initiated by suitable allyl or benzyl chlorides and BCl3. Accordingly, polymerizations of isobutylene have been carried out with RCl/BCl3, where R is allyl or benzyl. These experiments suggest that both controlled initiation and termination, i.e., initiation by alkenylation and termination by chlorination, can be achieved with the allyl chloride/BCl3 initiator system opening new avenues toward the synthesis of asymmetric telechelic polymers.
Evaluation of crosslinking and scission yields in the degradation of polystyrene by γ‐irradiation in air
Authors: Nichol J. M. , O'Donnell J. H. , Rahman N. P. , Winzor D. J. 
Published: April 2003

AbstractA sample of polystyrene with narrow molecular weight distribution (M̄w/M̄n = 1.03) has been formed into a 3‐mm sheet and subjected to γ‐irradiation at 25°C in air. Simultaneous crosslinking and scission of polymer chains resulted. Analyses by velocity and equilibrium sedimentation, gelpermeation chromatography, and osmometry of the polystyrene subjected to doses in the range 0‐90 Mrad, all within the pre‐gel region, have yielded average values of G(S) = G(X) = 0.022 ± 0.002 for the complete sample. Combination of these various experimental techniques has been successful in yielding consistent values of G(S) and G(X) and should be applicable with advantage to other polymers, particularly when neither G(S) nor G(X) is zero. The wide variation in literature values of G(S) and G(X) for irradiation of polystyrene under vacuum precludes any unequivocal conclusion on the effect of air on the radiation yields.
Preparation and structure‐property studies on copolypeptides of γ‐methyl glutamate‐glutamic acid and γ‐methyl glutamate–γ‐benzyl glutamate
Authors: Mohadger Y. , Holaday W. , Wilkes G. L. 
Published: April 2003

AbstractA series of copolypeptides of poly(methyl glutamate‐glutamic acid) (PBC) and poly(methyl benzyl glutamate) (PMB) were prepared from homopolymeric poly(methyl D‐glutamate) (PMDG) via a variety of synthetic routes. Following their characterization, these copolymers were then investigated via dynamic mechanical spectroscopy, stress‐strain analysis (wet and dry), and wide‐angle x‐ray scattering (WAXS). It was found that the copolymers could be prepared from homopolymeric PMDG with minimal chain degradation or side reactions. The mechanical properties of either series did not follow a simple trend, in that specific properties such as Young's modulus went through either a maximum or minimum with composition ratio of the two comonomers. based on the WAXS studies, some rationalization for this behavior was established. Specifically, the nature of the side‐chain interaction, and therefore chain packing, was strongly affected by comonomer ratio.
Photo‐ and radiation‐induced degradation of vinyl polymers in solution. I. Oxidative degradation of poly(α‐methylstyrene) initiated by photodecomposition of AIBN
Authors: Ikeda Tomiki , Okamura Seizo , Yamaoka Hitoshi 
Published: April 2003

AbstractThe oxidative degradation of poly(α‐methylstyrene) initiated by the photodecomposition of azobisisobutyronitrile was studied at 30°C in benzene solution. The progress of the reaction was followed by measuring the rate of chain scission of the polymer. It has been confirmed by GPC measurements that random scission of the polymer chain occurs in the present system. Chain scission did not occur in the absence of AIBN and oxygen. The rate was proportional to the initiation rate and independent of polymer concentration and oxygen pressure under these experimental conditions. Phenol was an effective inhibitor to this reaction. The mechanism of chain scission during oxidation is discussed, and a six‐membered transition is proposed.
Functional monomers and polymers. XXXVIII. Postirradiation polymerization of 2,3‐dimethylbutadiene in deoxycholic acid canal complexes
Authors: Miyata M. , Morioka K. , Takemoto K. 
Published: April 2003

AbstractPostirradiation polymerization of 2,3‐dimethylbutadiene in deoxycholic acid canal complexes was studied under various reaction conditions. The polymerization was carried out in degassed sealed tubes since the atmosphere had a large effect upon the polymer yield. Addition of 2,3‐dimethylbutane led to a sharp drop in polymer yield, while hydroquinone showed little effect on the polymerization. The rate of postirradiation polymerization was found to increase with increase in reaction temperature and irradiation dose. The apparent activation energy was obtained as 13.7 kcal/mole in a temperature range between −14 and 30°C. Existence of living free radicals having a long lifetime, the gradual change of the monomer into the polymer within the canals, and the effective spatial control in canals are discussed on the basis of the postirradiation polymerization behavior, nature of the adducts, and the structure of the polymers.
Adsorption of metal ions on crosslinked poly(4‐vinylpyridine) resins prepared with a metal ion as template
Authors: Nishide Hiroyuki , Deguchi Jichio , Tsuchida Eishun 
Published: April 2003

AbstractPoly(4‐vinylpyridine) (PVP) was crosslinked with 1,4‐dibromobutane with a metal ion as template. The adsorption behavior of copper, cobalt, zinc, and cadmium ions on the obtained resin (DBQP) was studied. The DBQP resin prepared with a metal ion as template preferentially adsorbed the metal ion used as template. The stability constant of the copper complex of DBQP was largest for the DBQP resin prepared with a copper ion as template, which was due to its large entropy change for the complexation.
Analysis of the linear methods for determining copolymerization reactivity ratios. IV. A comprehensive and critical reexamination of carbocationic copolymerization data
Authors: Kelen Tibor , Tüdöus Ferenc , Turcsányi Béla , Kennedy Joseph P. 
Published: April 2003

AbstractIncreased insight into the mechanism of carbocationic copolymerization has been achieved by classifying and reviewing in detail 334 monomer pairs in terms of the extended Kelen‐Tüdös method. The reactivity ratios (r values) of essentially all published olefin–olefin, olefin–vinyl ether, vinyl ether‐vinyl ether, and some miscellaneous systems have been reexamined and classified. Of the systems reviewed, only 121 (36.2%) contained sufficiently detailed information for comprehensive reevaluation and classification. Of these, only 49 (14.7%) were found to contain sufficiently accurate and reliable data to satisfy acceptance in class I, i.e., systems which are adequately described by the conventional copolymer composition equation, while 40 (12%) were accepted only in class I(!), i.e., systems for which the available data are somewhat less reliable than for class I and some caution is in order when employing r values for quantitative purposes. Six (1.8%) monomer pairs were judged to belong to class II, i.e., systems for which the approximations implicit in the conventional copolymer composition equation do not hold and published r values are probably erroneous and misleading. Finally, 26 (7.8%) monomer pairs were placed in class III, i.e., systems that exhibit unacceptable data scatter in the η versus ξ plot and published r values are meaningless. In some instances, even the existence of true copolymers is questioned.
Organometallic polymers. IV. Organometallic modifications of halogen‐containing polymers
Authors: Gal Alon , Cais Michael , Kohn David H. 
Published: April 2003

AbstractThe synthesis of ferrocene‐containing polymers by chemical modification of chlorinated polyethylenes, polyvinyl chloride (PVC), and other halogenated polymers, under Friedel‐Crafts conditions, is described. The effect of reaction conditions on the structure and composition of the products obtained with various substrates was investigated. Soluble polymers of up to 62% ferrocene content were obtained. In most cases, substitution was accompanied by dehydrohalogenation. The ferrocene‐to‐vinylene ratio was higher in the reaction products of chlorinated polyethylenes than in those of PVC.
Effect of polyion conformation on dye binding. I. Fluorescence of acridine orange in the presence of synthetic polyacids
Authors: Muller G. , Fenyo J. C. 
Published: April 2003

AbstractThe interaction between polyelectrolytes and Acridine Orange (AO) has been investigated in the case of poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), and a polycondensate between 1,3‐benzene disulfonyl chloride and L‐lysine (PLL) by visible absorption and fluorescence spectroscopy. The influence of both polymer ionization and polymer/dye ratio (P/D) on the spectral behavior of the bound dye has been studied. The stacking tendency of AO is found lower in the presence of PLL under compact conformation (in an ionization range depending on the nature of the counterion) with correlated enhancement of the green fluorescence of the monomeric species of the bound dye. The disappearance of the green fluorescence and the dimerization of bound AO are directly related to the increased flexibility of polyion chains upon ionization. Some analogy is found between the behavior of bound AO in the presence of very compact PLL chains and that reported for AO in the presence of native DNA, which might be due to specific interactions responsible for a kind of “intercalation” of the monomeric bound dye.
Influence of the fire retardant, ammonium polyphosphate, on the thermal degradation of poly(methyl methacrylate)
Authors: Camino G. , Grassie N. , McNeill I. C. 
Published: April 2003

AbstractThe thermal degradation of ammonium polyphosphate (APP), a commercial fire retardant, and its blends with poly(methyl methacrylate) (PMMA) have been studied by thermal volatilization analysis (TVA) and the degradation products identified. APP degrades under vacuum in three stages. Initially it condenses to an ultraphosphate (<260°C) with release of ammonia and water. Fragmentation follows (260–370°C), giving high‐boiling ammonium salts of phosphate fragments and further ammonia and water. The polyphosphoric acid (PPA) which remains then undergoes extensive Fragmentation (>370°C). In the presence of APP, the normal depolymerization of PMMA to monomer competes with degradation reactions which form high‐boiling chain fragments, methanol, carbon monoxide, dimethyl‐ether, carbon dioxide, hydrocarbons, and char. These additional reactions are initiated principally by the PPA. Intramolecular cyclization occurs, resulting in the formation of anhydride, and ester groups are eliminated, methanol and carbon monoxide being evolved. Further degradation of the modified polymer leads to the other volatile products and the char.
Characterization of diallyl phthalate prepolymers by gel‐permeation chromatography
Authors: Błędzki A. , Prusinska M. I. , Berek D. 
Published: April 2003

AbstractThe polydispersity of diallyl phthalate prepolymers was determined by gel‐permeation chromatography (GPC). The measurements were carried out in tetrahydrofuran and chloroform on Mexel 2000, Poragel, and Styragel polystyrene gels. The influence of the polymerization conditions, initiator, and type of transfer agent on the molecular weight distribution of the prepolymers is shown. Other correlations of interest, such as molecular weight distribution of Dapon 35 and Dapon 201, are also presented.