bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reaction of poly(vinyl alcohol) with pentavalent vanadium ion
Authors: Ikada Yoshito , Nishizaki Yasuko , Uyama Yoshikimi , Kawahara Tomoe , Sakurada Ichiro 
Published: April 2003

AbstractThe reaction of poly(vinyl alcohol) (PVAL) with V(V), i.e., pentavalent vanadium ion, was studied in aqueous H2SO4 medium. The viscosity change of reaction mixture with time showed a peculiar feature owing to formation of labile complex between V(V) and PVAL and the subsequent decomposition of the complex. On the other hand, the change of viscosity disappeared when NaOH was added during the reaction to neutralize H2SO4 in the reaction mixture. Under a suitable condition, the reaction mixture set to a gel as a result of complex formation. It appeared that reactive sites in PVAL responsive to complexing with V(V) were 1,2‐glycol unit and 1,2‐ketoalcohol unit resulting from the oxidation of 1,2‐glycol by V(V). The rate of oxidation was increased with increasing H2SO4 concentration. The main‐chain scission of PVAL took place to an insignificant extent, unless the reaction condition was severe. Based on the results obtained a reaction mechanism has been proposed.
Studies of the polymerization of diallyl compounds. XXIV. Effect of temperature on the polymerization of diallyl phthalate
Authors: Matsumoto Akira , Inoue Isao , Oiwa Masayoshi 
Published: April 2003

AbstractThe effect of temperature on the polymerization of diallyl phthalate was investigated in the temperature range of 80–150°C. The degree of polymerization increased slightly with temperature up to 100°C and then decreased; together with the results of primary chain length and the dependence of Rp on initiator concentration, these findings were interpreted in terms of the enhancement of the reinitiation ability of the allylic radical produced by the intramolecular chain‐transfer reaction and of the reactivity of the cyclized radical at elevated temperature. The tendency for cyclization became more marked with increasing temperature. The gel point was almost unaffected.
Formation of free radicals in photoirradiated cellulose and related compounds
Authors: Hon Nyok‐Sai 
Published: April 2003

AbstractFree‐radical formation in various modifications of celluloses, namely, wood cellulose I, II, III, and IV, rayon cellulose, amorphous cellulose, cotton linters, and absorbent cotton, irradiated with ultraviolet light, has been studied by means of ESR spectroscopy at 77°K. Various types of free radicals were generated from these samples. The line shapes and the signal intensities of the ESR spectra depended greatly upon the degree of crystallinity, the lattice type, and the arrangement of molecules in cellulose. The effect of degree of crystallinity and the amount of sensitizer (Fe3+) absorbed revealed that photochemical reactions in cellulose occurred exclusively in the amorphous regions of the polymer. Free radicals formed in these samples behaved distinctively upon a warm‐up process. Phenomena of radical migration and formation of new radicals were observed from the sensitized samples of rayon cellulose and amorphous cellulose.
Dimethylaniline (DMA)–Cu2+ ion system‐induced graft polymerization of methyl methacrylate on viscose
Authors: El‐Rafie M. H. , Waly A. I. , Hebeish A. 
Published: April 2003

AbstractGraft polymerization of methyl methacrylate on viscose fibers induced by the DMA–Cu2+ ion system was investigated under different conditions. Variables studied include concentration of DMA, Cu2+ ion, and MMA, reaction time, and temperature. There are optimal concentrations of DMA and Cu2+; below or above these concentrations lower grafting occured. Within 4 hr reaction time, the grafting reaction showed an initial fast rate followed by a slower one at 80°C. At 70°C, on the other hand, the graft yield increased in proportion to the increase in reaction time. Increasing the monomer concentration did not have a significant effect on the graft yield during the first 45 min of reaction. Beyond this, the effect of monomer concentration was marked.
Syntheses of functional condensation polymer. I. Polyesters having pendant functional groups such as hydroxyl, formyl, aldoxime, aminomethyl and hydroxymethyl
Authors: Ogata Naoya , Sanui Kohei , Shimozato Yasuyuki , Munemura Sho 
Published: April 2003

AbstractUnsaturated polyesters having pendant functional groups such as hydroxyl, formyl, aldoxime, aminomethyl and hydroxymethyl, have been prepared and characterized, and some of their properties were investigated. Reaction conditions for the epoxidation of unsaturated polyesters and hydrolysis of the epoxy groups in the polyesters were established to control the amount of pendant diol groups. It was possible to incorporate up to 90 mole‐% of formyl side groups into the unsaturated polyester by the hydroformylation with the rhodium catalyst. In addition, the formyl side groups of the modified polyester were converted into hydroxymethyl or aldoxime groups and were then converted to amino groups. The melting points of the modified polyesters decreased with increasing the pendant group content of the polyesters, as expected. Aliphatic polyesters having pendant hydroxyl or amino groups had a high affinity for moisture, which might be ascribed to the participation of the hydrophilic pendant groups in the modified polyesters.
Synthesis and characterization of polyaryloxyphosphazene copolymers
Authors: Dieck Ronald L. , Goldfarb Louis 
Published: April 2003

AbstractA series of polyaryloxyphosphazene copolymers with the general formulas [NP(OC6H5)(OR)]n and [NP(OC6H4–4–OCH3)(OR)]n, where R = C6H4–4–CH3, C6H4–4–C2H5, C6H4–4–isoC3H7, C6H4–4–sec‐C4H9, C6H4–4–tert–C4H9, C6H4–4–OCH3 or C6H4–4–OC4H9, have been prepared under anhydrous conditions. Copolymers as well as selected homopolymers were prepared by the reaction of polydichlorophosphazene with appropriate sodium aryloxides. Each of the polymers was characterized by elemental analysis, infrared spectroscopy, gel–permeation chromatography, and differential scanning calorimetry. Elemental analysis established the empirical formula for the polymers and showed that there were no residual PCl bonds left on the polymer backbone. Infrared spectroscopy indicated the presence of a phosphorus–nitrogen backbone with two aryloxy groups bonded to each phosphorus atom. The copolymers examined exhibited molecular weights of above 1 × 106. Polyaryloxyphosphazene copolymers were examined by differential scanning calorimetry and compared to several of the corresponding homopolymers. Glass transition temperatures ranged between −34 and +44°C for the polymers. The Kelley‐Bueche equation was used to predict the glass transition temperatures of the copolymers. Close agreement was found between calculated and experimental values for most of the systems examined.
Study of the degradation of polyurethanes. III. Mechanism of the photodegradation of polyurethane
Authors: Osawa Zenjiro , Cheu Eng‐Liang , Nagashima Kosaku 
Published: April 2003

AbstractThe effect of triplet sensitizers, benzophenone and anthraquinone and metal acetylacetonates [Co(II, III), Cu, Sn, and Ni] on the photodegradation of polyurethane was examined. Ultravioletvisible (UV‐V) absorption spectra, gel formation, and luminescence emission of the polymer before and after irradiation were measured. Changes in UV‐V absorption of the polymer and the formation of an insoluble fraction in the polymer were accelerated in the presence of the triplet sensitizers, and (Co(II, III)), Cu, and Sn acetylacetonates. Unirradiated polyurethane was excited by irradiation at 290 and 346 nm, and emitted light at 310 and 420 nm. After 1/2 hr irradiation emission of luminescence was observed at 430 nm, excitation at 290 and 346 nm; after 2hr irradiation at 530 nm, excitation at 420 nm was observed. The results suggest that photodegradation of the polyurethane proceeds via excited triplet states forming excimer between the polymers at the initial stage and exciplexes between the polymer and degradation products or intermediates after a certain irradiation.
Synthesis of polyarylamines by vinylogous nucleophilic substitution polymerization of bis(4‐chloro‐3‐nitrophenyl) sulfone with diamines
Authors: Imai Yoshio , Ueda Mitsuru , Otaira Kouetsu 
Published: April 2003

AbstractA series of new polyarylamines was prepared by the vinylogous nuclephilic substitution polymerization of bis(4‐chloro‐3‐nitrophenyl) sulfone with both aromatic and aliphatic diamines. The synthesis involves the solution polycondensation in a polar aprotic solvent at elevated temperatures, a tertiary amine being used as an acid acceptor. Of these solvents, dimethyl sulfoxide and N‐methyl‐2‐pyrrolidone were the most effective for the preparation of high molecular weight polymers. The polyarylamines having inherent viscosities in the range of 0.1–0.5 were all amorphous and highly soluble in polar aprotic solvents. Thermogravimetric analysis under both air and nitrogen atmospheres indicated that rapid decomposition began above 300°C for the polyarylamines from aromatic diamines.
Photodegradation of carbon monoxide–styrene copolymer in benzene and formation of block copolymer with methyl methacrylate
Authors: Kawai Wasaburo 
Published: April 2003

AbstractPhotodegradation of carbon monoxide–styrene copolymer in benzene was investigated. In relation to the average number of main‐chain scissions per macromolecule versus photoirradiation time, the straight line did not pass through the origin. This phenomenon was attributed to the presence of a labile bond from the carbonyl group in the main chain, in accordance with the results of Cameron and Lawrence which were found in the study of photodegradation of thermally polymerized polystyrene. In utilization of photodegradative behavior in carbon monoxide–styrene copolymer, a block copolymer of styrene with methyl methacrylate was prepared and was ascertained by precipitated fractionation, elementary analysis, and turbidimetry.
Stereoregularity of poly(2‐vinylpyridine) and poly‐(4‐vinylpyridine)
Authors: Matsuzaki Kei , Matsubara Tetsuyuki , Kanai Taiichi 
Published: April 2003

AbstractIn order to determine the stereoregularity of poly(4‐vinylpyridine), 4‐vinylpyridine‐β,β‐d2 was synthesized from 4‐acetylpyridine. The 1H‐NMR spectra of the deuterated and nondeuterated polymers were measured and analyzed. From the 1H‐NMR spectra of poly(4‐vinylpyridine‐β,β‐d2), triad tacticity can be obtained, while the 1H‐NMR spectra of nondeuterated poly(4‐vinylpyridine) give the fraction of isotactic triad. The 13C‐NMR spectra of poly(4‐vinylpyridine) were also observed, and the spectra of C4 carbon of polymers were assigned by the pentad tacticities. The fraction of isotactic triad of poly(2‐vinylpyridine) and poly(4‐vinylpyridine) obtained under various polymerization conditions were determined. The radical polymerization and anionic polymerizations with phenylmagnesium bromide and n‐butyllithium as catalysts of 4‐vinylpyridine gave atactic polymers.
Kinetics of polymerization rate based on the dependence of termination rate on chain length
Authors: Ito Katsukiyo 
Published: April 2003

AbstractWhen the structure of a primary radical resembles that of the chain end of the polymer radical, the rate of the primary radical termination is approximately the same as the termination rate between the oligomer radical and the polymer radical. The rate constant of termination between polymer radicals of chain length n and s, which involve the primary radicals, is kt,ns = const.(ns)−a. In the polymerization of methacrylonitrile initiated by 2,2′‐azobisisobutyronitrile in dimethylformamide at 60.0°C, the value of a is found to be 0.091. From data obtained previously in the bulk polymerization of styrene initiated by 1‐azobis‐2‐phenylethane at 60.0°C, the value of a is found to be 0.167. Because such a values are so large that they are not estimated by the excluded volume, the termination rates are discussed by adding the dependence of the diffusion of the segments to that for chain length.
Hydroperoxide‐initiated copolymerization of sulfur dioxide and cyclohexene. I. Characterization of charge‐transfer complex and initiation
Authors: Oster Bernd , Lenz Robert W. 
Published: April 2003

AbstractThe copolymerization of cyclohexene and sulfur dioxide to form an alternating copolymer was initiated by tert‐butyl hydroperoxide. The enthalpies and entropies of formation of the cyclohexene‐sulfur dioxide charge‐transfer complex, which is present during the copolymerization, were determined in two solvents by means of ultraviolet spectroscopy. The reduction of ultraviolet absorption during copolymerization afforded a convenient means of investigating reaction kinetics. No evidence of the direct involvement of the complex in polymerization initiation was found. The observation that the use of unpurified cyclohexene led to spontaneous initiation appears to point to adventitiously formed hydroperoxide rather than the charge‐transfer complex as providing initiating radicals which are produced by the redox reaction of the hydroperoxide with sulfur dioxide. A competing heterolytic scission reaction was found to result in the formation of tert‐butyl peroxide and sulfuric acid. This reaction caused the polymerization reaction to stop after a short period of time due to a time‐dependent decrease in initiator concentration.
Structure of chlorinated poly(vinyl chloride). IV. Chlorination of β,β‐d2‐poly(vinyl chloride) as model for determination of the mechanism of chlorination
Authors: Lukáš R. , Kolínský M. , Doskočilová D. 
Published: April 2003

AbstractChlorinated β,β‐dideuterated poly(vinyl chloride) (β,β‐d2‐CPVC) was prepared by photochemical suspension chlorination in concentrated hydrochloric acid with chloroform as swelling agent, and thermally in tetrachloroethane solution. 1H‐NMR (nuclear magnetic resonance) spectra of β,β‐d2‐CPVC were recorded. The content of deuterium was determined in combustion products of β,β‐d2‐CPVC as the D2O:(H1D)2O ratio by means of mass spectroscopy. Both in the photochemical suspension chlorination and in the thermal solution chlorination of β,β‐d2‐PVC, a decrease of the concentration of CHCl groups was observed. The differences in structure of the suspension chlorinated and solution chlorinated β,β‐d2‐PVC were confirmed.
Kinetics and mechanism of the emulsion polymerization of styrene in the aqueous media at 50°C and at low monomer concentration initiated by persulfate. I. Initiation
Authors: Chatterjee S. P. , Banerjee Monoranjan , Konar R. S. 
Published: April 2003

AbstractThe mechanism of the water‐soluble persulfate‐initiated emulsion polymerization of styrene in the aqueous media at 50°C has been investigated kinetically by the conventional dilatometric and gravimetric methods at low concentration of the monomer (5% v/v). It has been found that the initial rate of polymerization Vp is approximately proportional to initiator concentration [I] to the 0.50 power, i.e., Vp ∝ [I]0.50, and the viscosity‐average molecular weight Mv is approximately inversely proportional to the 0.50 power of the initiator concentration, i.e., Mv ∝ [I]−0.50. With the progress of the reaction, the initiator exponent of the reaction rate equation decreases gradually from 0.50 to 0.25, but that of the molecular weight (1) equation remains constant up to 20% conversion and thereafter begins to decrease. Since the kinetic data at zero conversion satisfy the steady‐state kinetics of the free‐radical‐initiated homogeneous vinyl polymerization, it is suggested that the initiation of emulsion polymerization of styrene is a two‐step process. It starts in the aqueous phase by the primary free radicals from the water‐soluble initiator or secondary free radicals derived from the soap molecules. The second step occurs in the monomer‐leaded micelles by the water‐soluble or water‐insoluble macroradicals or by radicals derived from the soap molecules. The latter are likely to be produced in the aqueous phase by the oxidation of soap with S2O82−ions or SO4− radicals. It has been noted that the rate of thermal decomposition of persulfate increases by a factor of 6–8 times under different experimental conditions in the presence of soap.
Bisorthoesters as polymer intermediates. II. A facile method for the preparation of polybenzimidazoles
Authors: Dudgeon C. D. , Vogl O. 
Published: April 2003

AbstractAromatic bisorthoesters were found to be good polymer intermediates and could be condensed with aromatic tetramines under mild conditions, in DMSO at 100°C in a relatively short reaction time to give polybenzimidazoles. The hexapropyl orthoesters of terephthalic and isophthalic acid were the preferred aromatic orthoesters because they were relatively easily purified by vacuum distillation to polymer grade intermediates, since they are liquids. Higher orthoesters distill even under good vacuum near or above the decomposition temperature of the orthoester group. Hexaethyl orthooxalate was also used and is a very useful and stable derivative of oxalic acid, which can be used for condensation reactions. These three orthoesters were used for condensations with 3,3′,4,4′‐tetraaminobiphenyl, 1,2,3,4‐tetraaminobenzene, 3,3′,4,4′‐tetraaminobiphenyl ether, and 3,3′,4,4′‐tetraaminobenzophenone. All polybenzimidazoles were obtained in high to quantitative yields and with varying molecular weights (ηinh = 0.1−0.8 dl/g), which in some cases were in the fiber forming range.
On the mechanism of the polymerization of poly(vinyl chloride)
Authors: Caraculacu A. , Buruiană E. C. , Robilă Gabriela 
Published: April 2003

AbstractThe polymerization of poly(vinyl chloride) (PVC), head‐to‐head macroradical plays an essential role in the formation of branches and the appearance of interruption processes that lead to labile unsaturated end groups. A reaction mechanism is suggested to explain these processes and the method of formation of internal double bonds as a result of transfer to polymer. The transfer to monomer can occur only by atom acceptance by the macroradical and not by the monomer giving up an atom.
Photodegradation of polyethylene in the presence of ferric salt: Influence of ferric acetylacetonate on model compounds
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Kimura Yuji 
Published: April 2003

AbstractThe influence of ferric acetylacetonate [Fe(acac)3] on the photodegradation of model compounds of polyethylene (PE) was examined. By studying electron‐spin‐resonance (ESR) spectra of photoirradiated compounds such as 1‐octene and 1,7‐octadiene, which contain carbon double bonds, Fe(acac)3 was found to accelerate the formation of allyl radical by contact with them. On the other hand, Fe(acac)3 suppressed the radical formation based on Norrish type I reaction in a carbonyl group of compounds such as 2‐octanone and 3‐octanone. Based on the study of ultraviolet (UV) spectra as well as ESR spectra on photoirradiated samples, the influence of Fe(acac)3 on the photodecomposition of model compounds of PE was discussed. Finally, the discussion turned to the mechanism of photodecomposition of PE in the presence of ferric salt.
Alternating copolymerization of benzofuran with crotononitrile and α‐chloroacrylonitrile
Authors: Furukawa Junji , Kobayashi Eiichi , Nagata Shiro 
Published: April 2003

AbstractThe copolymerizations of benzofuran with α,α‐ or α,β‐disubstituted acrylic monomers were studied. The alternating copolymer of benzofuran and crotononitrile was prepared in the presence of an excess amount of crotononitrile with respect to benzofuran, ethylaluminum dichloride, and azobisisobutyronitrile. The intrinsic viscosity of copolymers was 0.1–0.2 dl/g. Crotononitrile is known to possess a polar carbon–carbon double bond from 13C‐NMR spectroscopy but the alternating copolymerizability with benzofuran is low. It was found that the order of alternating copolymerizability of acrylic monomers is as follows:

This fact may be attributed to the steric hindrance of the β‐methyl of crotononitrile. The induced shifts by complexation with ethylaluminum dichloride on 13C‐NMR spectra of the two isomers of crotononitrile are almost same but the copolymerizability of cis isomer is higher than that of trans isomer.α‐Chloroacrylonitrile shows the highest alternating copolymerizability with benzofuran in the presence of weak Lewis acid such as ethoxyaluminum chloride. Alternating copolymerizability of acrylic monomers seems to be in proportion to their e value. The reactivity of cis‐ and trans‐crotononitrile may depend on the nature of a ternary complex composed of aluminum compound, crotononitrile, and benzofuran.
The cationic dimerization of 1,1‐diphenylethylene. III. Kinetics of initiation by aluminum chloride
Authors: Masure M. , Sauvet G. , Sigwalt P. 
Published: April 2003

AbstractKinetics of the reaction of AlCl3 with 1,1‐diphenylethylene (DPE) in CH2Cl2 solution have been investigated at low temperature by ultraviolet (UV) spectrophotometry. Initiation proceeds in three successive stages. The first, very fast and leading to a low and constant concentration of carbocations, is assigned to residual traces of cocatalyst. A second stage, slower but more extensive, yields about one carbocation for two aluminum in a reaction that is first order in AlCl3 and first order in monomer (ki = 2.5 10−2 liter mole−1 sec−1 at −30°; Ei = 10 kcal mole−1). This stage, which takes place after consumption of residual cocatalyst, should be attributed to a direct initiation. In a proposed mechanism the cationic intermediate produced by reaction of DPE with AlCl3 transfers a proton to DPE, thus leading to a stable diphenylethyl cation and to alkenyldichloroaluminum (Al‐Cl2CHCPh2). A third stage develops slowly and the yield in carbocations finally reaches 65–70% with respect to AlCl3. This stage is tentatively assigned to a second direct initiation by the less active organoaluminum compound formed in the preceding stage.
ESR studies of trapped free radicals and polymer deposition in xylene plasmas
Authors: Scott Thomas W. , Chu Keh‐Chang , Venugopalan M. 
Published: April 2003

AbstractRates of polymer deposition and radical trapping in xylene plasmas produced in a Siemens tube with 60‐Hz current decreased linearly with increasing flow rate but increased linearly with power and decreased in the order ortho > meta > para at a constant flow rate and pressure. These results indicate that radical recombination and disproportionation are unimportant and that the polymerization rate equation is first order in free radical concentration.
Syntheses of N‐substituted carbazoles involving polymerizable terminal vinyl groups
Authors: Kamogawa Hiroyoshi , Koizumi Hitoshi , Nanasawa Masato 
Published: April 2003

AbstractEleven N‐substituted carbazoles (CZ) with terminal vinyl groups were synthesized by five sequences of reaction: N‐(p‐vinylbenzyl)‐ and N‐β‐(vinyloxyethyl)CZ by N‐alkylations of potassium CZ with corresponding chlorides; N‐(β‐acryloyloxyethyl)CZ by the esterification of N‐(β‐hydroxyethyl)CZ with acryloyl chloride; N‐acrylamido‐or methacryl‐amido‐methyl CZ from N‐hydroxymethyl CZ and acryl‐ or methacrylamide; N‐(3‐acryloyl‐ or methacryloyl‐oxy‐2‐hydroxypropyl)CZ and N‐[3‐(p‐ or m‐vinylanilino)‐2‐hydroxypropyl] CZ from N‐(2,3‐epoxypropyl)CZ and acrylic or methacrylic acid and p‐ or m‐vinylaniline, respectively; and 2‐[β‐(N‐carbazyl)propionyloxy]ethyl acrylate or methacrylate by the Michael addition of CZ to 2‐hydroxyethyl acrylate or methacrylate, followed by esterifications. The vinyl polymers with pendant carbazyl groups more or less distant from the polymer backbones, prepared by conventional radical or cationic polymerization procedures, indicated charge‐transfer spectra with 2,4,7‐trinitrofluorenone (TNF) in tetrahydrofuran (THF) solutions that are spread over most of the visible range.