bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. V. Effects of p‐benzoquinone and dose rate on methyl methacrylate–silica gel system
Authors: Fukano Kazuyuki , Kageyama Eiichi 
Published: April 2003

AbstractIn order to elucidate the mechanism of radiation‐induced polymerization of methyl methacrylate adsorbed on silica gel, the effects of p‐benzoquinone addition and dose rate were studied in detail. Most of the polymerization is inhibited by p‐benzoquinone at levels above 10‐2 mole/l. The GPC spectra of both graft polymers and homopolymers show two peaks. The high molecular weight material appears to have been formed by polymerization by a radical mechanism, because these peaks decrease as p‐benzoquinone concentration increases; on the other hand, their low molecular weight polymers seem to be products of an ionic polymerization mechanism because those peaks are almost not affected by p‐benzoquinone. The four GPC peaks differ in dose rate dependences of their polymerization rate. The dose‐rate exponents of polymerization rate were obtained for the four GPC peaks. The behavior of the low molecular weight peaks of graft polymers and homopolymers were quite different, suggesting that the polymers differ considerably in formation mechanism.
Synthesis of polypropionamide‐ureas from N‐mesyloxysuccinimide and diamines
Authors: Imai Yoshio , Ueda Mitsuru , Ishimori Motokazu 
Published: April 2003

AbstractA series of polypropionamide‐ureas was synthesized by the polymerization of N‐mesyloxysuccinimide with diamines in polar aprotic solvents in the presence of acid acceptors. The polymerization proceeded through the formation of ring‐opened adducts, followed by elimination and rearrangement yielding β‐isocyanatopropionamide derivatives, which in turn were polymerized to afford polypropionamide‐ureas. These polymers had inherent viscosities in the range of 0.1–0.2. Polymers having aliphatic chains which were fusible below 240°C were soluble in acidic solvents, whereas those with aromatic residues dissolved in polar aprotic solvents. Marked decomposition of the polyamide‐ureas under thermogravimetric analysis generally occurred at around 320°C under nitrogen.
Photopolymerization via the Paterno‐Büchi reaction. I. Reaction of aromatic diketones with tetramethylallene
Authors: Andrews D. J. , Feast W. J. 
Published: April 2003

AbstractAromatic diketones of the benzophenone type undergo photopolymerization on irradiation at 350 nm with tetramethylallene in benzene solution. The polymers produced contain oxetane units in the main chain, and spectroscopic analysis demonstrates that the distribution of structural units parallels that found in the reaction between benzophenone and tetramethylallene. The polymers are rapidly degraded thermally and by mineral acids.
Copolymerization of styrene with vinyltriethoxysilane and vinyltriacetoxysilane
Authors: Bajaj P. , Khanna Y. P. , Babu G. N. 
Published: April 2003

AbstractStyrene was copolymerized in bulk with vinyltriethoxysilane at 80°C and vinyltriacetoxysilane at 60, 80, and 100°C with the use of benzoyl peroxide as an initiator at low conversions. Copolymer composition was determined from the silicon content and reactivity ratios were calculated by the conventional scheme of copolymerization. The low r1 value (styrene) in the styrene‐vinyltriacetoxysilane system (St–VTAS) as compared to styrene‐vinyltriethoxysilane (St–VTES) copolymerization may be attributed to higher reactivity of VTAS towards the polystyryl radical. Further, in the St–VTAS system, r1 tends to decrease with increasing polymerization temperature. The influence of silicon comonomer on properties of the copolymers (intrinsic viscosity, solubility, dielectric and thermal behavior) was studied.
Chemorheology of linear polymers. II
Authors: Murakami Kenkichi , Nakanishi Hiromasa 
Published: April 2003

AbstractThe chemical stress relaxation of crosslinked polymers had long been studied. The chemorheology of linear polymers is difficult to study because molecular flow by diffusion is generally much more rapid than relaxation or flow caused by chemical reaction. Our previous paper dealt with the chemorheology of linear polymers on taking such physical flow into consideration. By using another modified expression suggested by Tobolsky, good consistency between the theoretical chemical stress relaxation curve and an experimental one was obtained for polydisperse polystyrene and the commercial polystyrene used.
Polystyrene degradation induced by stresses resulting from the freezing of its solutions
Authors: Abbas Kent B. , Porter Roger S. 
Published: April 2003

AbstractSolutions of polystyrene in p‐xylene were frozen in liquid nitrogen. No changes in molecular weight and distribution were caused by freezing solutions for a series of narrow distribution polystyrenes with molecular weights of near 2 × 106 and lower. Likewise a commercial polystyrene of M̄w = 234,000 showed no change, even after 45 cycles of freezing and thawing. However, an ultrahigh molecular weight polystyrene (M̄w = 7.3 × 106) showed appreciable degradation even after a few freezing cycles of its solutions. The changes in molecular weight and distribution were analyzed by gel‐permeation chromatography. The results depended very much on the choice of solvent, cooling rate, and concentration. The extent of degradation was found to depend on polymer concentration in two distinct ways. Indeed, two different degradation mechanisms have been distinguished at low and at high concentrations. The change between mechanisms took place between 1.0 and 2.5 g/l. for polystyrene in p‐xylene. This appears to provide a rare measure of polymer‐polymer interactions (entanglements) in dilute solutions. Degradation in the entanglement region proceeded via a random chain‐scission mechanism as tested by the Scott method. In contrast, at low concentrations degradation was characterized by the formation of appreciable amounts of low molecular weight polystyrene. The presence of an antioxidant (Ionol) during freezing did not change the extent of degradation significantly.
Anionic polymerization. III. Polymerization of butadiene with alkali metal alkoxide‐modified alkali metal system
Authors: Cheng Tai Chun , Halasa Adel Farhan 
Published: April 2003

AbstractA high molecular weight polybutadiene was prepared in hexane solvent by using alkali metal (Li, Na, K) and metal tert‐butoxide (Li, Na, K) as a polymerization initiator. The microstructure of polybutadiene varies, depending on the type of modifiers and polymerization and temperatures. The results and mechanistic implications of this study are discussed.
Synthesis of polybenzodipyrrolediones by thermal cyclodehydration of polyamides derived from dibenzylidenebenzodifurandiones and aliphatic diamines
Authors: Ueda Mitsuru , Takahashi Takeyoshi , Imai Yoshio 
Published: April 2003

AbstractA new class of polyheterocycles, polybenzodipyrrolediones (PBP), has been synthesized successfully by the two‐step polymerization of dibenzylidenebenzodifurandiones with aliphatic diamines. New bislactone monomers, 3,5‐dibenzylidene‐3,5‐dihydro‐1H,7H‐benzo[1,2‐c:4,5‐c′]difuran‐1,7‐dione and 3,7‐dibenzylidene‐3,7‐dihydro‐1H,5H‐benzo[1,2‐c:4,5‐c′]‐difuran‐1,5‐dione, were synthesized from pyromellitic dianhydride and phenylacetic acid. The ring‐opening polyaddition reaction of the bislactones with aliphatic diamines in a polar solvent afforded novel polyamides having inherent viscosities of 0.1–1.0 in quantitative yield. The solution polymerization was almost completed within several hours at 80°C, while it required approximately a week to its completion at room temperature. Dimethyl sulfoxide and N‐methyl‐2‐pyrrolidone were preferred solvents for the polymerization. The open‐chain polyamides were subsequently cyclodehydrated by heating at 240°C to give PBP having high molecular weight. The aliphatic PBP were soluble in hot polar solvents such as N‐methyl‐2‐pyrrolidone, m‐cresol, and nitrobenzene. They began to decompose at about 400°C in a nitrogen atmosphere as determined by thermogravimetric analysis.
Degradation of polymer mixtures. VII. Blends of poly(vinyl acetate) with polystyrene
Authors: Jamieson A. , McNeill I. C. 
Published: April 2003

AbstractThe degradation of films containing both PVA and PS has been investigated for comparison with the behavior already reported for PVC/PS blends. The presence of PS had little, if any, effect on the behavior of PVA, but PVA had an effect similar to that of PVC on the degradation of PS. Styrene production was retarded in the blend, compared to PS alone, and an increase in the rate of chain scission was observed for a high molecular weight sample. The molecular weight effect, however, was much smaller than in corresponding experiments with PVC/PS blends. Interference with intermolecular transfer in PS is again advanced as the probable explanation of the stabilization of PS.
ESR study of linear aliphatic oligoesters under γ‐irradiation. I. Paramagnetic species produced in the material by irradiation at 77°K
Authors: Ooi Toshitami , Mimura Koji , Hama Yoshimasa , Shinohara Kenichi 
Published: April 2003

AbstractParamagnetic species produced in a series of linear aliphatic oligoesters $ [\bond;{\rm O}\bond;({\rm CH}_{\rm 2} {\rm )}_m\bond;{\rm O}\bond;{\rm CO}\bond;({\rm CH}_{\rm 2} {\rm )}_n\bond;{\rm CO\rlap{--} ]}_P $ by γ‐irradiation at 77°K was investigated by an ESR method. A predominant doublet observed immediately after γ‐irradiation, which has hyperfine splitting of 20–23 gauss, is attributed to a radical anion III.
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Slight decay of this radical anion is observed by illuminating the sample with visible light at 77°K. A small amount of the radical anion is converted to double triplet, which is assigned to (ES)CHCH2 (where ES denotes the ester group), from the result of heat treatment. The conformational angles for the two β‐protons in the (6,2) oligoester are determined to be θ1 = θ2 = 30°.
Effect of nonpolar field formed by polymer ligand on the oxidation of 2,6‐xylenol catalyzed by Cu complexes
Authors: Tsuchida Eishun , Nishikawa Hiroshi , Terada Eiichi 
Published: April 2003

AbstractThe oxidative polymerization catalyzed by Cu(II)‐poly(vinylpyridine) derivatives and the effect of the nonpolar field formed by the polymer ligand on the catalysis was studied in dimethyl sulfoxide (DMSO) solvent. The catalytic activity of the Cu complex increases in the following order; Cu‐(styrene‐vinylpyridine copolymer) (St·VP) complex > Cu‐partially quarternized (by benzyl chloride) poly(vinylpyridine)(BCQP) complex > Cu‐poly(vinylpyridine) (PVP) complex > Cu‐pyridine (Py) complex > Cu‐partially quarternized (by ethyl bromide) poly(vinylpyridine) (EBQP) complex. This order is the same as that of the reoxidation rate constant of the catalyst. Acceleration of ko process in Cu‐St>VP and Cu‐BCQP systems, where the active site is in the nonpolar field formed by the polymer ligand, is explained by an increase in strength of the coordination bonds.
Sulfur‐containing vinyl monomers. XIII. Cationic copolymerizations of vinyl sulfides with some vinyl monomers
Authors: Inoue Hiroshi , Otsu Takayuki 
Published: April 2003

AbstractCationic copolymerizations of vinyl sulfides (VS) with some vinyl monomers with boron tri‐fluoride‐diethyl etherate catalyst were investigated to evaluate their monomer reactivities. The effects of VS on the copolymer yield and viscosity of the resulting copolymers revealed the inhibition or retardation mechanism which was explained in terms of the formation of a stable vinylsulfonium salt by the reaction between a propagating carbonium ion and VS monomer. From the results of copolymerizations of phenyl vinyl sulfide (PVS) with isobutyl vinyl ether (IBVE), β‐chloroethyl vinyl ether (CEVE), α‐methylstyrene (α‐MeSt), and styrene (St), the relative reactivities of these monomers were found to be in the following order: IBVE > CEVE > PVS > α‐MeSt > St. The relatively higher reactivity of PVS than St derivatives was explained on the basis of the conjugative and electron‐donating nature of the VS monomer. The effects of alkyl and para‐substituted phenyl groups in vinyl sulfides on their reactivities toward the propagating carbonium ion were correlated with polar factors and compared with those of the hydrolysis of α‐mercaptomethyl chlorides. The transition state for the propagation reaction in cationic polymerization of VS was proposed to be a π‐complex type structure.
Electrical properties of poly‐trans‐2,5‐dimethylpiperazine‐fumaramide. I.D.c. Conductivity by a new instrumentation
Authors: Sandrolini F. , Manaresi P. 
Published: April 2003

AbstractThe d.c. conductivity of a recently synthesized polyamide, poly‐trans‐2,5‐dimethylpiperazine‐fumaramide, was investigated by a new instrumentation designed for measuring very low conductivity in insulating materials over broad ranges of temperature and environmental conditions. The instrumentation system allows measurements based on the voltmeter‐ammeter method according to ASTM D‐257, under atmospheres from high vacuum to a pressure of several times atmospheric of the desired gas and at temepratures from room to about 300°C, with an overall accuracy usually better than 10%. The material was examined in form of powder as well as film, in the dry and hydrated state, usually under vacuum up to about 200°C. The polymer behaves as an insulating material and exhibits a great increase in conductivity with water content. The results obtained do not permit a detailed discussion of the actual conduction mechanism. Although it seems to be primarily electronic in nature, an ionic contribution increasing with temperature cannot be excluded. There is no protonic contribution to the conduction because of the absence of N‐H groups in the molecular chains.
Cleavage of poly(vinyl alcohol) in the presence of tert‐butyl hydroperoxide and biologically active metal complexes
Authors: Jochsberger T. , Auerbach A. , Indictor N. 
Published: April 2003

AbstractThe cleavage of poly(vinyl alcohol) in dimethyl sulfoxide at 42°C has been measured viscometrically in the presence of tert‐butyl hydroperoxide and metal complexes. Phthalocyanine complexes of copper(II), iron(III), cobalt(II), and vanadium as VO(II) as well as hemin, hematin, chlorophyllin, and cytochrome c were used. The rates of decomposition of tert‐butyl hydroperoxide in the presence of these metal complexes were measured idometrically. These data are compared to results obtained with other metal complexes in similar reactions.
Cyclopolymerization. V. Monomer design for the synthesis of highly cyclized polymer from unsymmetrical unconjugated dienes: Synthesis and polymerization of N‐methyl‐N‐allylmethacrylamide
Authors: Kodaira Toshiyuki , Ishikawa Masaki , Murata Osamu 
Published: April 2003

AbstractN‐Methyl‐N‐allylmethacrylamide (MAMA) was synthesized and polymerized with radical initiators, and the structure of poly‐MAMA was studied, in order to establish the concept that difunctional monomers having monofunctional counterparts which do not polymerize are likely to give rise to highly cyclized polymer, if the cyclized polymer is in a lower free‐energy level than the monomer. The cyclopolymerizability of MAMA was considerably higher than that of N‐allylmethacrylamide, which was previously reported, and its monofunctional counterpart can be polymerized. The extent of cyclization of poly‐MAMA was about 93%, even in the polymer obtained by bulk polymerization. The repeating units of poly‐MAMA consist mainly of five‐membered rings; six‐membered rings and pendent methacryl groups were detected in addition as minor repeating components. The monofunctional counterparts of MAMA, i.e., N‐methyl‐N‐n‐propylmethacrylamide (MPMA) and N‐methyl‐N‐allylisobutyramide (MAIA), were also synthesized. Neither MPMA nor MAIA showed any tendency toward polymerization under the same experimental conditions as used for MAMA. The results thus obtained all support the concept mentioned above.
Synthesis of polyamides by ring‐opening polyaddition of benzobis[1,2]oxazinediones with aliphatic diamines
Authors: Ueda Mitsuru , Hazome Hisashi , Imai Yoshio 
Published: April 2003

AbstractNovel oxime‐containing polyamides have been prepared by the ring‐opening polyaddition of combinations of two benzobis[1,2]oxazinediones, 4,6‐diphenylbenzo[1,2‐d:5,4‐d′]bis[1,2]oxazine‐1,9‐dione and 4,9‐diphenylbenzo[1,2‐d:4,5‐d′]bis[1,2]oxazine‐1,6‐dione, with two aliphatic diamines in a polar aprotic solvent such as N‐methyl‐2‐pyrrolidone. The polymerization was almost completed within a day at room temperature. These polymers had inherent viscosities in the range of 0.12–0.38 and were soluble in a wide range of solvents, including formic acid and hot m‐cresol, as well as a number of polar aprotic solvents. All the polymers softened at a temperature ranging from 165 to 185°C. Thermal characterization of the polyamides by TGA and DTA showed polymer decomposition temperatures of about 240°C in air.
Polyamides from perchloro‐4,4′‐dichloroformylbiphenyl
Authors: Escobar H. , Díaz F. R. , Ramíarez R. S. 
Published: April 2003

AbstractNew thermally stable polyamides were prepared by low‐temperature polycondensation in N,N‐dimethylacetamide from perchloro‐4,4′‐dichloroformylbiphenyl and various aromatic and aliphatic diamines. The polymers were characterized by infrared spectroscopy, elemental analysis, TGA, and DSC and found to show higher thermal stability than other nonchlorinated polyamides.
Effect of solvent in radical polymerization of butadiene 1‐carboxylic acid
Authors: Bando Yoshihumi , Minoura Yuji 
Published: April 2003

AbstractThe radical polymerization and copolymerization of butadiene 1‐carboxylic acid (Bu‐1‐Acid) were studied in a variety of the electron‐donor solvents such as dimethylformamide (DMF), tetrahydrofuran (THF), methyl ethyl ketone (MEK), acetonitrile (ACN), and benzene (BZ) using AIBN as an initiator at 50°C. Under these conditions, the polymerization rate of Bu‐1‐Acid increased in the order, DMF < THF < MEK < ACN < BZ in the various solvents. In copolymerization with styrene [M2] and acrylonitrile [M2], the monomer reactivity ratio r1 increased and r2 decreased in the same order. Moreover, it was found that Alfrey‐Price Q‐e value of Bu‐1‐Acid increased depending on solvent in the order DMF < THF < MEK < ACN < BZ. These variations were correlated to the electron‐donating power (Δvcm−) of the solvents used and are discussed on the basis of the solvation of Bu‐1‐Acid into the solvent. Also, it was found that the microstructures of these polymers were always trans‐1,4 and did not change with the solvent used.
Effect of pH on radical polymerization of butadiene 1‐carboxylic acid in aqueous solutions
Authors: Bando Yoshihumi , Minoura Yuji 
Published: April 2003

AbstractRadical polymerization of butadiene 1‐carboxylic acid (Bu‐1‐Acid) was carried out in aqueous solutions at 50°C with ammonium persulfate (APS) as an initiator. Kinetic studies led to the rate equation, Rp = k[APS]1/2 [Bu‐1‐Acid]1 at pH 6.8. The overall activation energy for the polymerization was 16.0 kcal/mole. The polymerization rate Rp of Bu‐1‐Acid decreased with an increase of pH in the range 2.4–6.8 and increased with an increase of pH in the range 6.8–8.4. Moreover, in the pH range 8.4–13, the rate of polymerization was not affected by the pH of the system. In copolymerization with acrylonitrile, the trends of changes in the monomer reactivity ratios r1, r2 and Q‐e values caused by changes in pH were similar to trends found in homopolymerization described above. In addition, it was observed that the resultant polymer was extended in alkaline solution and contracted in acidic solution.
ESR study of radiation‐induced polymerization of methyl methacrylate on solid surfaces
Authors: Yoshioka Hisashi , Matsumoto Hidenobu , Uno Shinpey , Higashide Fukuji 
Published: April 2003

AbstractESR spectra of methyl methacrylate (MMA) adsorbed on solid surfaces such as silica, alumina, and CPG‐10 show a seven‐line absorption due to monomer radicals when γ‐irradiated at −196°C. These spectra turn into conventional nine‐line spectra by annealing at −86°C as a result of polymerization. The intensity ratio of the four‐line component to the five‐line component changes with further polymerization. The ratio depends on the kind of solid and the smallest value is obtained in the spectra of alumina‐MMA. The temperature of irradiation strongly affects the value in alumina‐MMA. These results suggest that MMA is strongly adsorbed and deformed the conformation on alumina surface.
Polymerization initiated by an electron donor–acceptor complex. VI. Polymerization of methyl methacrylate initiated by a liquid SO2–nicotine complex and carbon tetrachloride
Authors: Matsuda Minoru , Ishioroshi Yasuhiro , Seki Kiichiro 
Published: April 2003

AbstractA kinetic study has been made of polymerization of methyl methacrylate initiated by an electron donor–acceptor complex of liquid SO2 (electron acceptor) and nicotine (donor) in the presence of carbon tetrachloride. It is concluded that the polymerization proceeds through free‐radical intermediates similar to the cases of liquid SO2–pyridine and liquid SO2–poly(2‐vinylpyridine) complexes. The overall rate of polymerization is proportional to the square root of both liquid SO2 and nicotine concentrations, and the values of kp/kt½ under various polymerization conditions are in satisfactory agreement with the literature values. For the activation energy of initiation, 13.6 kcal/mole is estimated from the kp/kt½ values obtained at temperatures ranging from 0 to 80°C.
Hydrogen‐transfer polymerization of methyl‐substituted acrylamides
Authors: Otsu Takayuki , Yamada Bunichiro , Itahashi Masaki , Mori Takashi 
Published: April 2003

AbstractBase‐catalyzed hydrogen‐transfer polymerization and copolymerization of acrylamide and its methyl‐substituted derivatives were studied in pyridine at 110°C. n‐Butyllithium was used as an initiator. The observed rates of these homopolymerizations were found to decrease in the following order: acrylamide > crotonamide > methacrylamide > N‐methylacrylamide > N‐methylcrotonamide > tiglinamide > N‐methylmethacrylamide ≫ α‐chlorocrotonamide ≃ α‐cyanocrotonamide = 0. Acrylamide gave the polymer with the highest degree of polymerization among the monomers examined. It was found that the number and the position of the methyl substituent in acrylamide affected significantly both the rate of polymerization and the molecular weight of the polymer. Although all polymers obtained, except the N‐methyl derivatives, contained both methanol‐soluble and methanol‐insoluble fractions, a polyamide structure with unsaturated terminal monomer unit was confirmed by both infrared and NMR determinations. From the NMR determination of the saturated and terminal unsaturated units, the degree of polymerization of the resulting polyamides were also obtained. The monomers were also found to copolymerize by a hydrogen‐transfer mechanism. However, the main chain of the resulting copolymers was composed of the more reactive monomer unit, and the less reactive monomer was incorporated only as a terminal unit when a less reactive monomer was copolymerized with a more reactive one. From these results, it was concluded that these polymerizations proceeded via an intermolecular hydrogen‐transfer mechanism (i.e., stepwise mechanism).