bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of 4‐vinylpyridinium salts. III. A clarification of the mechanism of spontaneous polymerization
Authors: Salamone J. C. , Snider B. , Fitch W. L. 
Published: April 2003

AbstractThe mechanism of the spontaneous polymerization of 4‐vinylpyiridine on quaternization or protonation has been investigated. Results indicate that initiation is caused by the nucleophilic attack of 4‐vinylpyridine on the double bond of 4‐vinylpyridinium ion. It was shown that halide ions do not contribute significantly to the initiation. In the case of acid salts of 4‐vinylpyridine a hydrogen‐transfer polymerization occurred to give an ionene polymer with pyridinium units in the main chain. The “matrix” polymerization of 4‐vinylpyridine on poly(phosphoric acid) or poly(acrylic acid) also resulted in ionene formation. Conditions under which stable 4‐vinylpyridinium salts can be obtained are discussed.
Effect of formaldehyde on the cationic polymerization of styrene
Authors: Fukuda Wakichi , Ogata Norio , Kakiuchi Hiroshi 
Published: April 2003

AbstractPolymerization of styrene has been carried out in the presence of formaldehyde at 30°C in benzene solution by using boron trifluoride etherate as a catalyst. The rate of polymerization in the initial stage was accelerated with addition of formaldehyde, while the steady‐state rate of polymerization was retarded in the presence of formaldehyde. The acceleration for the rate of polymerization was found only in a short time from the beginning. The steady‐state rate of polymerization followed the equation:

where [C]0 and [F]0 are initial concentrations of catalyst and formaldehyde, [M] is the monomer concentration, and k1, k2, and k3 are constants. It has been assumed that the chain‐transfer reaction does not involve formaldehyde itself but rather the reaction products of formaldehyde, such as polystyrene having ethoxy or hydroxymethyl ends. The apparent chain‐transfer constant for the added formaldehyde has been determined to be 1.63.
Complex of copper(II) with phenoxo and hexamethylphosphoramide ligands and its decomposition
Authors: Tsuruya S. , Kawamura T. , Yonezawa T. 
Published: April 2003

AbstractThe 2,4,6‐trichlorophenoxo–hexamethylphosphoramide(HMPA)–copper(II) complex was isolated by the reaction of copper(II) chloride with 2,4,6‐trichlorophenol, sodium methoxide, and HMPA in methanol solvent under an atmosphere of nitrogen. This complex has the composition of Cu·HMPA·2(C6H2Cl3O). The molecular weight determination was consistent with the copper(II) complex of binuclear structure. The infrared, electronic, and ESR spectra and magnetic susceptibility of the copper(II) complex are discussed in relation to its structure. Decomposition of the copper(II) complex in refluxing benzene yielded poly(dichlorophenylene oxide), coupling product of the 2,4,6‐trichlorophenoxo ligand of the copper(II) complex. Electron spin resonance (ESR) measurements on the copper(II) complex in the solid state in a degassed sealed tube at 120 ± 5°C indicated that the phenoxy radical was generated during the period of decomposition and the intensity of the ESR spectra based on copper(II) ion decreased with the measurement time. From these ESR spectra, a possible initial step involving one electron transfer of the decomposition of the 2,4,6‐trichlorophenoxo–HNPA–copper(II) complex is discussed.
Vinyl polymerization initiated by chromic acid–reducing agent systems
Authors: Viswanathan S. , Santappa M. 
Published: April 2003

AbstractA kinetic study of the thermal polymerization of acrylonitrile initiated by chromic acid–reducing agent (n‐butanol, ethylene glycol, cyclohexanone, and acetaldehyde) systems was made. Chromic acid alone did not initiate polymerization under deaerated or undeaerated conditions. On the basis of the experimental determination of the dependencies of various variables on the rate of polymerization Rp, the rate of chromium (VI) disappearance −RM, the degree of polymerization DP, etc., a reasonable kinetic scheme was arrived at. The mechanism with the reducing agents, n‐butanol, cyclohexanone, and ethylene glycol, was found to be similar but different from that with acetaldehyde. Evidence has been presented to prove the formation of radical intermediates formed by the oxidation of the reducing agent by Cr(IV). Rate parameters for oxidation of the reducing agent and polymerization of the monomer were evaluated.
Triad tacticity of polyacrylonitrile
Authors: Matsuzaki Kei , Okada Munehisa , Uryu Toshiyuki 
Published: April 2003

AbstractThe high‐resolution NMR spectra of polyacrylonitrile‐β,β‐d2 prepared by radical polymerization were determined, and the stereoregularity of the polymer was studied. The NMR spectra of methine protons of polyacrylonitrile‐β,β‐d2 in dimethyl sulfoxide‐d6 and a mixture of nitromethane‐d3 and ethylene carbonate showed three partially resolved multiplets. The deuterium‐decoupled spectra of the polymer were measured, and three well resolved peaks were observed in the two solvents and dimethylformamide‐d7. These three peaks were analyzed by comparison with the NMR spectra of model compounds and polyacrylonitrile‐α‐d, and they were assigned to isotactic, heterotactic, and syndiotactic triads with decreasing magnetic field. This order seems to be unchanged in other solvents. Triad stereoregularity of the polymer was determined according to the assignment. Polymerizations of acrylonitrile‐β,β‐d2 by radical initiators between −78°C and 60°C were explained by the Bernoulli trial propagation step. The polymers had an atactic structure, independent of polymerization temperature. This shows that in free‐radical polymerization of acrylonitrile, the chain end is not represented as having any particular stereochemistry. Other stereochemical control is necessary to produce tactic polymers. The triad tacticity of isotactic polyacrylonitrile was also determined.
Interfacial synthesis of polyphosphonate and polyphosphate esters. V. Poly(phosphonate esters) containing thymidine, 2‐deoxy‐d‐ribose, or xanthine
Authors: Millich F. , Carraher C. E. 
Published: April 2003

AbstractPoly(phosphonate esters) were synthesized by base‐promoted interfacial polycondensation of phenylphosphonic dichloride with thymidine and with 2‐deoxy‐D‐ribose. The products give evidence of P‐Cl endgroups. The thymidine product is a high polymer with a weight‐average number of repeating units, DPw, greater than 250. The 2‐deoxy‐D‐ribose product is separable into soluble and insoluble (crosslinked) fractions having identical infrared spectra. Xanthine is also reactive in the process employed.
Copolymerization characteristics of S‐vinyl‐O‐tert‐butylthiocarbonate
Authors: Daly W. H. , Lee Chien‐Da S. , Overberger C. G. 
Published: April 2003

AbstractPoly‐S‐vinyl‐O‐tert‐butylthiocarbonate is an excellent precursor to poly(vinyl mercaptan) because the tert‐butyloxycarbonyl blocking group can be removed by either acid hydrolysis or thermolysis under conditions which minimize the oxidation of the liberated mercaptan to disulfide. Dilatometric studies of the homopolymerization of S‐vinyl‐O‐tert‐butylthiocarbonate demonstrated that the polymerization rate was directly proportional to the concentration of free‐radical initiator; no thermal initiation was observed. The molecular weight of the homopolymers and copolymers ranged from 30,000 to 50,000 (GPC). Copolymerization of S‐vinyl‐O‐tert‐butylthiocarbonate (M2) with styrene, (r1 = 3.0, r2 = 0.2), methyl methacrylate (r1 = 1.40, r2 = 0.17) and vinyl acetate (r1 = 0.04, r2 = 11.0) indicated that a sulfur atom adjacent to the vinyl group increases the resonance stability (Q2 = 0.5) and the electron density (e2 = −1.4) of the double bond and the corresponding radical. Water‐soluble copolymers could be prépared by incorporating either N‐vinylpyrrolidone (r1 = 0.12, r2 = 3.94) or N‐isopropylacrylamide (r1 = 1.17, r2 = 0.3) with M2. The water solubility of the copolymers decreased markedly when the tert‐butyloxycarbonyl group was removed. Copolymers of M2 with N‐vinyl‐O‐tert‐butylcarbamate (r1 = 0.13, r2 = 5.10) were utilized to prepare crosslinked poly(vinyl amine–vinyl mercaptan); the crosslinking resulted from urea linkages formed during thermolysis of the copolymer.
Electroinitiated polymerization of vinylic monomers in polar systems. II. Polymerization of ethyl methacrylate in methanol solutions
Authors: Albeck Michael , Relis Joseph 
Published: April 2003

AbstractEthyl methacrylate is polymerized by electroinitiation in methanol–electrolyte mixtures in which the monomer is soluble whereas the polymer obtained is insoluble. A technique of changing the polarity of the electrodes is used. With this technique a polymer of high molecular weight can be obtained. The relationships between molecular weight and monomer concentration, current densities, and time of the reaction as well as the yield as a function of current density, time of the reaction and initial monomer concentration are given. A free‐radical mechanism is proposed for the reaction.
Polybenzopinacolones. Acid‐catalyzed rearrangement of aromatic polybenzopinacols
Authors: McCombs D. A. , Menon C. S. , Higgins Jerry 
Published: April 2003

AbstractPolybenzopinacols resulting from the photocondensations of p,p′‐dibenzoyldiphenyl ether, p,p′‐dibenzoyldiphenylmethane, and p,p′‐dibenzoyl‐1,2‐diphenylethane were rearranged in sulfuric acid–dioxane solutions. The inherent viscosities of the polybenzopinacolones did not differ significantly from the inherent viscosities of the polybenzopinacols after rearrangement. A model compound study by NMR and infrared methods indicated that the polymer chain was probably the main migrating group for each of the polymer rearrangements.
Grafting on wool. I. Electron microscopic studies on the location of grafted polymer in wool structure
Authors: Arai Kozo , Negishi Michiharu 
Published: April 2003

AbstractTo determine the location of grafted poly(methyl methacrylate) in orthocortex structure of fine Australian Merino wool fibers, high‐resolution electron microscopy was used. Optimal staining conditions for the observation of the deposited polymer were also studied. It was supposed that the grafted polymer is located mainly between the microfibril and matrix and around the protofibrillar subunits, but not in the matrix. The average space occupied by a grafted chain was estimated to be about four times as large as the total residue volume per polymer. It is supposed that the remarkably large space available per polymer chain is related to the excessive swelling seen with respect to the polymer uptake.
Grafting on wool. II. Stress–strain behavior of grafted fiber in water
Authors: Arai Kozo , Negishi Michiharu , Suda Tsutomu , Doi Kazuko 
Published: April 2003

AbstractThe stress–strain behavior and hysteresis properties of various grafted wool fibers were studied. Three distinct regions on the stress–strain curve and hysteresis properties characteristic of the native wool fiber remain substantially intact, even though a large amount of a rigid polymer occurs. It was suggested that the microfibril and the matrix nature in the native wool fiber exist in the grafted wool structures. The electron microscopic results were also supported. These results can be explained on the basis of Menefee's model that the longitudinal mechanical behavior is more directly controlled by a high modulus matrix.
Determination of chlorine distribution in chlorosulfonated polyethylenes by high‐resolution NMR spectroscopy
Authors: Brame Edward G. 
Published: April 2003

AbstractHigh‐resolution proton magnetic resonance (NMR) spectroscopy was used to determine the sequence distribution of chlorines in elastomeric chlorosulfonated polyethylenes. The determination is based on measuring the relative amounts of methylene groups that are α, β, and γ (or greater) from chlorine containing groups (CHCl groups) in chlorosulfonated polyethylenes. The results obtained from the NMR examination at 220 MHz were compared with the theoretical predictions based on the statistics of substitution polymers. The comparison showed that polyethylenes chlorosulfonated by a solution reaction with gaseous chlorine and sulfur dioxide show a random chlorine distribution.
Effect of pH on the reactivity ratios in the copolymerization of acrylic acid and acrylamide
Authors: Cabaness W. R. , Lin T. Yen‐Chin , Párkányi C. 
Published: April 2003

AbstractThe content of acrylic acid and acrylamide in their copolymers can be controlled by changing pH. The reactivity ratio of acrylic acid decreases with increasing pH, while the reactivity ratio of acrylamide increases with increasing pH. At low pH values, acrylamide is present in its protonated form which causes its reactivity to be low whereas at high pH values the reactivity of acrylic acid is decreased owing to its dissociation. When the monomer and radical approach each other, the acrylate anion becomes the least reactive species because of its symmetrical charge distribution, like charge repulsion and barium ion screening effect. HMO calculations were performed for models of all monomers and polymer radicals involved in copolymerizations. The experimental results concerning the reactivity of acrylic acid and acrylamide in copolymerization and the observed reactivity ratios were discussed on the basis of HMO calculations and resonance and Coulomb electrostatic effects. The observed reactivity ratios were correlated with the calculated differences in resonance energies computed for the models of transition states involved in copolymerizations.
Gel‐permeation chromatography. V. A study of “overloading effects”
Authors: Ouano A. C. 
Published: April 2003

AbstractIn the calculation of molecular weight averages from GPC chromatograms and in the correction for zone broadening effects, it is assumed that the retention volumes of the individual species are not affected by the presence of the other components in the sample (linear fractionation process). This assumption was tested by the computer comparisons of the chromatograms of mixtures of narrow molecular weight distribution polystyrene standards and the envelopes of the individual chromatograms of the components of the mixtures. Disagreements between experimental and computer synthesized chromatograms were interpreted as non‐linear fractionation effects. The investigation covered a range of molecular weights (1.8 × 106 to 2100), molecular weight distributions (binary and seven component mixtures), and sample loadings (2 to 70 mg). Accurate normalizations of raw GPC chromatograms and calculations of molecular weight averages were made possible through an automated GPC apparatus using a high‐speed computer for data acquisition and data reduction. It was found that some nonlinear fractionation effects (large disagreement between chromatograms of the mixture and the computed envelopes of the individual chromatograms of the components of the mixture) became more pronounced as sample loading was increased and as the molecular weight distribution of the sample narrows. The nonlinear effect was also found to be sensitive to the molecular weight of the sample.
Analysis of resoles by gel‐permeation chromatography
Authors: Wagner E. R. , Greff R. J. 
Published: April 2003

AbstractResoles, the complex, heat‐sensitive product mixture from the alkali‐catalyzed reactions of phenol with formaldehyde were investigated by gel‐permeation chromatography (GPC). The low molecular weight species of these resins which consisted of mono‐and dinuclear methylol phenols were resolved into multiple peaks. Model compounds were used to identify the peaks of the specific methylol phenols or methylene etherbridged diphenols. Differences in the refractive index of individual species restricted the quantitative analysis of low molecular weight components in the resole. The effects of sodium and barium hydroxides and hexamethylene‐tetramine as catalysts, reaction temperature, and time on the total composition of a resole are demonstrated with the gel‐permeation chromatographic spectrum and with the aid of NMR. Formation of a “secondary” resole by methylolation of the bisphenol of formaldehyde was also monitored by GPC.
Study of the reaction of polyester resins with magnesium oxide
Authors: Alvey Francis B. 
Published: April 2003

AbstractThe reaction of polyester resin and magnesium oxide, which is the basis of the thickening process of sheet‐molding compound technology, has been characterized in a systematic study. The effect of reactant equivalency ratios, temperature, and added water on viscosity development have been determined. Excess amounts of magnesium oxide are necessary for thickening. Water increases the initial rate of thickening but reduces the overall level attained. A new thickening mechanism is proposed on the basis of a model study with polyester resin and sodium hydroxide.
Polymerization of α‐methylstyrene by living polymer in tetrahydrofuran
Authors: Podolsky A. F. , Dashkin R. Ch. , Korotkov A. A. 
Published: April 2003

AbstractKinetics of polymerization of α‐methylstyrene by poly‐α‐methylstyrylsodium (a “living” polymer) has been studied in tetrahydrofuran at −78°C. Complex dependences were established: that of the conversion X on reduced time φ and that of the apparent rate constant for the polymer chain propagation on conversion X and on the concentration of living polymers and monomer. The experimental data obtained were explained by assuming a coordination mechanism of anionic polymerization including the following elementary reaction: (a) generation of active polymerization centers (K1) by interaction of the living polymer with the monomer; (b) propagation of the polymer chains (K2); (c) monomolecular (K31) and bimolecular (K32) reactions of isomerization of active centers resulting in the formation of high molecular weight living polymers capable of again becoming active centers of polymerization. Approximate derivation of kinetic equation was carried out and the constants of elementary reactions were determined (K1 = 0.15, K2 = 24, K32 = 14.1./mole‐min and K31 = 0.05 min−1). The coincidence of the expected dependencies X = F(τ; φ) Kp = F(X; n0−1/2); dx/dτ = F(n0) with the experimental ones was followed with the aid of computers. The expected change in the values of X and Kp depending on the contribution of each elementary reaction to the overall polymerization process was analyzed.
Helical concept of the fine structure of cellulose
Authors: Ahmed A. U. , Rapson W. H. 
Published: April 2003

AbstractThe helical concept of the fine structure of cellulose as proposed by Manley is discussed. The deuterium exchange experiments with cotton, cotton crystallites, and regenerated cellulose I, in which accessibility was determined by comparing the ratio of the infrared absorbance of the OD peak to the OH peak, revealed that the accessibility of cotton linters decreased on acid hydrolysis, whereas it increased on treatment with ethylamine followed by washing with water. This is in contrast to the finding of Manley, who had evaluated the accessibility by a gravimetric D2O exchange method and had come to the conclusion that acid hydrolysis did not change the accessibility of cellulose and hence cellulose did not contain crystalline and amorphous phases but was all crystalline. On the basis of Manley's protofibril and the accessibility data obtained in this investigation, a concept of the fine structure of cellulose is proposed, in which the role of Manley's protofibril is analogous to the role of individual molecule in the fringe micellar model. This concept explains the properties of cellulose that are otherwise explainable on the currently accepted fringe micellar theory. In addition, it explains the marked shrinkage in the length of cotton and rayon fibers when placed in 16% sodium hydroxide solution.
Free‐ionic polymerization of isobutyl vinyl ether by radiation
Authors: Hayashi Kanae , Hayashi Koichiro , Okamura Seizo 
Published: April 2003

AbstractRadiation‐induced free‐ionic polymerization of isobutyl vinyl ether in bulk system has been studied by dilatometry and electrical conductivity measurement. Some refinements in kinetic treatment of estimate the propagation rate constant kp from the rate of polymerization and steady‐state conductivity were attempted. Polymerization of superdried monomer which gave a half‐power dose‐rate dependence of Rp was carried out at 0, 25, and 50°C. The kp value obtained at 25°C and an activation energy for propagation were estimated as 1.2 ± 0.4 × 105 I./mole‐sec and 9.6 ± 2.8 kcal/mole, respectively. In isobutyl vinyl ether, a propagation reaction in free‐ionic mechanism was found to be characterized with a high frequency factor and presumably higher activation energy, compared with ion‐pair mechanism. Discussions were also made as to several contrasting behaviors between the polymerization of alkyl vinyl ethers and other vinyl monomers as styrene both in free‐ion and ion‐pair mechanisms.
Stereoregularity of radically polymerized poly(alkyl acrylates) and poly(trimethylsilyl acrylates) and the preparation of syndiotactic poly(methyl acrylate)
Authors: Uryu Toshiyuki , Shiroki Hiroyuki , Okada Munehisa , Hosonuma Kunihiko , Matsuzaki Kei 
Published: April 2003

AbstractNuclear magnetic resonance (NMR) spectroscopy was used to determine the stereoregularity of radically polymerized poly(ethyl acrylates), poly(trimethylsilyl acrylates), and poly(isopropyl acrylate‐α,β‐d2). The ethyl acrylate polymers consisted of a random configuration having about 50% of isotactic diads, and their stereoregularities were independent of the polymerization temperature (40 to −78°C). Poly(trimethylsilyl acrylates) and poly(isopropyl acrylate‐α,β‐d2) prepared at low temperatures had a syndiotactic configuration. Syndiotactic poly(methyl acrylate) was derived from syndiotactic poly(trimethylsilyl acrylate). For poly(methyl acrylate), an approximate estimation of the stereoregularity by infrared spectroscopy was proposed.
Analysis of polymerization rates in radical polymerization with primary radical termination of methyl methacrylate initiated by 2,2′‐azobis(2,4‐dimethyl valeronitrile)
Authors: Ito Katsukiyo 
Published: April 2003

AbstractPolymerization rates in radical polymerization of methyl methacrylate initiated by 2,2′‐azobis(2,4‐dimethyl valeronitrile) under various conditions were analyzed by using a previously derived simple equation. The results obtained are discussed on the basis of the relation of solvent viscosity and temperature. It is concluded that chain termination rate constant is inversely proportional to the solvent viscosity, but primary radical termination rate constant can not be related immediately to solvent viscosity.
Photo‐induced graft copolymerization of methyl methacrylate on cellulose
Authors: Ogiwara Yoshitaka , Kubota Hitoshi 
Published: April 2003

AbstractGraft copolymerization initiated by ultraviolet light irradiation at 40°C in a hard glass vessel under nitrogen was examined. The graft copolymerization was observed to occur easily after some induction period without any use of photosensitizer, though it was found the per cent grafting and the grafting efficiency were markedly affected by the quantities of cellulose and monomer. In the system without cellulose, homopolymerization of methyl methacrylate hardly took place, but the use of cellulose caused the formation of homopolymer too, and a grafting efficiency in the range of 60–80% generally resulted. Ferric chloride or sodium anthraquinone‐2,7‐disulfonate (AQ) acted on the polymerization reaction as photosensitizers to reduce its induction period. Though ferric chloride acted to develop both the per cent grafting and the number of grafts, not the same effects were observed with AQ. Oxalic acid, which was employed with the object of eliminating very small amount of metals contained in cellulose, was found to act favorably in the formation of grafts, much like ferric chloride.