bluuebunny/crossref_metadata_2025_split huggingface dataset:
Change with temperature of the ESR spectra of methacrylic acid radicals
Authors: Sakai Yoshiro , Iwasaki Machio 
Published: April 2003

AbstractIn order to elucidate the structure of methacrylic acid radicals, the change with observation temperature of the ESR spectrum of free radicals trapped in solid methacrylic acid γ‐irradiated at −196°C was studied. Below −80°C, we found a 9‐line spectrum, which is similar to the ordinary 9‐line spectrum observed in irradiated poly(methacrylic acid) or poly(methyl methacrylate), but which differs in the stronger intensity of the so‐called 4‐line component. Our 9‐line spectrum changes reversibly into a 13‐line spectrum above −80°C. With broad‐line NMR measurements of methacrylic acid, it was found that there is such an unusual crystalline transition around −30°C that the line width is narrower in the lower‐temperature region (phase II) than that in the higher‐temperature region (phase I). The change of the ESR spectrum can be interpreted in terms of the exchange of the two β‐protons due to the hindered oscillation around the CαCβ bond of the single radical ···CβH2Cα(CH3)COOH if one assumes the gradual change of the hindering potential barrier caused by the crystalline transition and the lower barrier in phase II. The modified Bloch treatment gave the hindering potential barrier to be 7.2 kcal/mole in phase I and 1.5 kcal/mole in phase II. The difference between our 9‐line spectrum and the ordinary one with the very weak 4‐line component comes from the difference of the surrounding matrix.
ESR study of radical sites in crystalline texture of irradiated polypropylene by means of nitric acid etching
Authors: Kusumoto Naoshi , Matsumoto Kazuki , Takayanagi Motowo 
Published: April 2003

AbstractBulk‐crystallized isotactic polypropylene samples with different crystalline textures were etched by fuming nitric acid to remove the disordered region. The radicals produced by irradiation of γ‐rays or ultraviolet light on these etched samples in vacuum at liquid nitrogen temperature were investigated by the ESR method. A triplet spectrum in addition to the original spectrum of polypropylene radicals was separated for the etched samples. It was concluded that this triplet was caused by radical species associated with nitro groups introduced on the surface of the crystalline residues by etching. The difference in the intensity of this triplet among the samples was ascribed to differences in crystalline textures and interpreted in a quantitative way. The concentration of polypropylene radicals corrected for the triplet differed among the quenched, annealed, and cold‐drawn samples and the sample annealed one after drawing. This fact was interpreted on the basis of the hypothesis that radical sites were almost concentrated in the defects of crystal domain. The well known nonet spectrum, which can be observed at liquid nitrogen temperature after annealing the irradiated samples at room temperature, was also confirmed to be attributable to the defects of crystals. The behavior of free methyl radicals induced by ultraviolet irradiation was also found to be strongly dependent on the state of aggregation of the polymer molecules.
Salt effect on polymer solutions
Authors: Saito Shuji 
Published: April 2003

AbstractThe salt effect was investigated by measurements of viscosity, cloud point, and solubility of aqueous solutions of poly(vinyl alcohol—acetate) copolymers, as these copolymers in water are sensitive in various ways to addition of various electrolytes. The major role in the salt effect is played by the anions, and water‐structure breaking anions produce salting‐in of the copolymers. Tetraalkylammonium halides (bromides and iodides) cause salting‐in of the copolymers more effectively with increase of size of the hydrophobic cations. The Setschenow equation does not hold for the polymers except for very dilute polymer concentration. In salts of monoalkyl‐substituted anions (RCOONa and RSO4Na) and cations (RNH3Cl and Br), so long as the alkyl chain is short, the salt effect is also dominated by the anions. With increase of the alkyl chain length, sodium salts of the monoalkyl‐substituted anions exert a stronger salting‐in effect upon the polymers than chlorides of similar long‐chain cations. The significance of the counteranions is suggested for the interaction of nonionic polymers and the long‐chain cations. The action of the salts on the copolymers is discussed in terms of medium effects (change of the water structure) and of the binding effect of the single ions to the polymers.
Polyindoloquinoxalines
Authors: Schopov I. , Popov N. 
Published: April 2003

AbstractTwo polymers, containing 6H‐indolo [2,3‐b] quinoxaline as a repeating unit, have been prepared by polycyclization of 5,5′‐biisatyl with 3,3′‐diaminobenzidine, and of 5,5′‐diisatyl ether with 3,3′,3,4′‐tetraaminodiphenyl ether in polyphosphoric acid. Their structure was established by comparing the infrared and electronic spectra of the newly obtained polymers with the corresponding spectra of four model compounds synthesized for the purpose. The electronic spectra showed conjugation along the chain of both the polymer with ether bonds and the one with single bonds between the rings. The two polymers gave an electronic paramagnetic resonance signal. The polyindoloquinoxalines showed good thermal stability in air and in nitrogen, the better stability being manifested by the polymer with single bonds between the rings.
Anionic graft polymerization of ethylene oxide on starch. I
Authors: Tahan Menashe , Zilkha Albert 
Published: April 2003

AbstractGraft polymers of polyethylene oxide on various starches were obtained by anionic graft polymerization of ethylene oxide on the starch alkoxide derivatives. The polyalkoxides were prepared by reaction of potassium naphthalene with starch in DMSO solution. It was found that increase of monomer or alkoxide concentration led to transformation of the grafts from solids to syrups. Rice starch, having a more complex structure than soluble starch or wheat starch, led to graft polymers having higher melting ranges than the others. The graft polymers were very soluble in water or methanol.
Anionic graft polymerization of ethylene oxide on starch. II. Structure of the graft polymers
Authors: Tahan Menashe , Zilkha Albert 
Published: April 2003

AbstractStarch–poly(ethylene oxide) graft polymers were prepared in DMSO at various monomer and starch alkoxide concentrations. Complimentary and varied information on the structure of the graft polymers was obtained from NMR and periodic acid oxidation of the polymers. From the NMR spectra of the graft polymers in pyridine containing a trace of HCl, which causes shifting of the resonance of the internal CH2O protons from the terminal CH2OH protons, the polyethylene oxide content, the DPn of the grafted side chains, and the efficiency of the alkoxides were calculated. With increase of the alkoxide concentration there was a small decrease in DPn, and in the efficiency of the alkoxides in initiating graft polymerization. With increase of monomer concentration, there was only a small increase in DPn but a large increase in the efficiency, indicating the existence of transfer reactions between the growing anions and the free hydroxyl groups on the starch. The results of he periodic acid oxidation showed that with increase of alkoxide concentration there was no significant change in the per cent oxidation of the graft polymers, but with increase of monomer, there was an increase in the participation of the secondary hydroxyl groups in initiation. This supports the NMR evidence for the existence of transfer reactions leading to DPn values much lower than those calculated from [monomer]/[catalyst] ratios.
Production of radicals in polyoxymethylene by ultraviolet photolysis: An EPR study
Authors: Hughes O. R. , Coard L. C. 
Published: April 2003

AbstractPolyoxymethylene (POM) was photolyzed at 2537 and at 3130 Å at −196°C. The EPR spectra of the radical intermediates were recorded. Photolysis in vacuo produces a small number of radicals, apparently due to the presence of traces of chromophores. Photolysis in oxygen, however, is a type of photo‐oxidation. The radicals HCO, , CH3·, and HOO· were detected and identified as intermediate products of photolysis. Hydrogen atoms and hydroxyl radicals were too reactive (i.e., mobile) at −196°C to be observed. Alkoxy and alkyl radicals and the POM peroxy radical
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were probably formed as well but could not be characterized with certainty.
Syntheses and reactions of functional polymers. XLVI. Preparation and reactions of N‐benzyloxyisomaleimide–styrene copolymer
Authors: Akiyama Masayasu , Yanagisawa Yasuhiro , Okawara Makoto 
Published: April 2003

AbstractPolymerization of N‐benzyloxymaleimide(I) was attempted to obtain a polymer with the N‐hydroxysuccinimide unit in the chain. In the light of infrared and NMR data the compound reported by Ames as N‐benzyloxymaleimide is N‐benzyloxyisomaleimide (III). Homopolymerization of III did not give polymer. Copolymerization of III with styrene was carried out in dioxane at 70°C. A strong alternation tendency like that of maleimides was observed. Monomer reactivity ratios and Q‐e values were determined. Copolymer having the isoimide structure showed infrared absorptions at 1815 and 1675 cm−1 in the carbonyl region. The copolymer was isomerized to N‐benzyloxymaleimide type copolymer and debenzylated to N‐hydroxymaleimide type copolymer. An insoluble copolymer was prepared by using divinylbenzene as a crosslinking agent and was converted to N‐acetoxymaleimide type copolymer, which was used as an insoluble acetylating agent.
Sulfur modification of polyethylene surfaces. I. Insertion of sulfur into polyethylene surfaces
Authors: Olsen Douglas A. , Osteraas A. Jean 
Published: April 2003

AbstractAtomic sulfur generated respectively by the pyrolysis of carbonyl sulfide and by the photolysis of carbonyl sulfide, carbon disulfide, and sulfur vapors has been shown to modify irreversibly the surface of polyethylene as shown by wettability measurements. The nature of the modification is not completely apparent from this portion of the study, however, insertion of the atomic sulfur into a carbon—hydrogen bond to form a surface thiol group appears likely. The modified surfaces thus formed are shown to undergo several classical organic reactions, as determined by wettability measurements.
Stereoblock polymerization of methyl methacrylate with VOCl3Al(C2H5)3 catalyst system
Authors: Dixit S. S. , Deshpande A. B. , Anand L. C. , Kapur S. L. 
Published: April 2003

AbstractKinetics of the polymerization of methyl methacrylate with the VOCl3AlEt3 catalyst system at 40°C in n‐hexane have been studied. A linear dependence of rate of polymerization on the monomer and catalyst concentrations as well as an overall activation energy of 5.87 kcal/mole were found. Characterization of the structure of the polymer by NMR spectra revealed the presence of stereoblock units. The mechanism of polymerization is discussed in relation to the kinetic data obtained.
Determination of penetrant solubility from transient permeation measurements
Authors: Paul D. R. 
Published: April 2003

AbstractThe permeability coefficient for the transport of a gas, vapor, or liquid through a polymer film is the product of the penetrant solubility and a diffusion coefficient. A transient permeation experiment known as the time‐lag technique can be used to separate this product, provided the diffusion coefficient is independent of penetrant concentration. In this well‐known experiment the polymer is initially free of penetrant. A new transient permeation experiment where the polymer is initially saturated with penetrant is suggested here. A general mathematical proof is given to show that by using the results form these two transient experiments which have different initial conditions one can determine the penetrant solubility no matter how the diffusion coefficient depends on penetrant concentration. Also one can determine two different concentration averaged diffusion coefficients from the results.
Application of preparative gel‐permeation chromatography to studies of low molecular weight carboxy‐polybutadienes
Authors: Law Ronald D. 
Published: April 2003

AbstractLow molecular weight carboxy‐polybutadiene liquid polymers are used as the binderfuel fraction in solid composite propellants. Analytical GPC determinations of low molecular weight materials (100 through 500 molecular weight range) were previously found to correlate significantly with final propellant properties. These low molecular weight materials are being characterized, and studies of their role in determining propellant physical properties are being conducted. Sufficient quantities of material in the 100–500 molecular weight range have been isolated by using preparative scale GPC to establish the chemical nature of these materials. Infrared and chemical analysis of fractions collected by using preparative GPC also has permitted the construction of functional group distribution profiles. In addition, narrow fractions isolated over the molecular weight range of the whole polymer were analyzed for average molecular weight by vapor pressure osmometry and have been used as calibration standards for analytical GPC.
Formation of free radicals during machining and fracture of polymers
Authors: Backman D. K. , Devries K. L. 
Published: April 2003

AbstractElectron paramagnetic resonance measurements of the number of free radicals formed during cutting and grinding of polymers are described. It was found in the semicrystalline polymers studied that below the glassy transition temperature that the number of free radicals formed is about 2 × 1013/cm2 of surface formed. It is proposed that this number results from the crack progressing selectively through the glassy regions about more ordered regions in the polymers.
Polymers from 12 α‐hydroxymethylabiet‐7,8‐enoic acid and vinyl 12 α‐hydroxymethylabiet‐7,8‐enoate
Authors: Saga Motoo , Marvel C. S. 
Published: April 2003

Abstract12 α‐Hydroxymethylabiet‐7,8‐enoic acid has been homopolymerized by melt condensation, and a partially crystalline polyester has been obtained. Vinyl 12 α‐hydroxymethylabiet‐7,8‐enoate has been prepared from 12 α‐hydroxymethylabiet‐7,8‐enoic acid by vinyl interchange with vinyl acetate and has been homopolymerized, copolymerized with vinyl chloride, vinyl acetate, butadiene, and acrylonitrile, and terpolymerized with styrene and acrylonitrile. Polymers thus obtained have been characterized.
Low‐temperature polymerization of lactams by using as catalyst the salt derived from NaAlEt4 and monomer and with several compounds as initiator
Authors: Konomi T. , Tani H. 
Published: April 2003

AbstractLow‐temperature polymerization of α‐pyrrolidone, α‐piperidone, and ϵ‐caprolactam was examined by using the salts derived from NaAlEt4 and monomer, sodium lactamates, or the salt derived from AlEt3 and monomer as catalyst and with N‐acetyl lactams, ethyl acetate, or lactones as initiator. Sodium lactamate catalyst gave unsatisfactory results in the cases of ethyl acetate or lactones initiators, and gave the following order for the relative efficiency of initiators: N‐acetyl lactam > ϵ‐caprolactone ≥ ethyl acetate > β‐propiolactone. The polymerization results obtained by the salt from NaAlEt4 catalyst–ethyl acetate initiator system were nearly the same as those with N‐acetyl lactam. The increases in the degree of polymerization and in the yield of polymer were observed in case of the salt from NaAlEt4 catalyst‐lactone initiator system, particularly in the cases of α‐piperidone and ϵ‐caprolactam. Also an incorporation of initiator into polymer chain was observed.
Methyl methacrylate polymerization initiated by triethylborane–peroxide mixtures
Authors: Contreras J. , Grotewold J. , Lissi E. A. , Rozas R. 
Published: April 2003

AbstractThe polymerization of methyl methacrylate initiated by triethylborane or triethylborane–peroxide mixtures was studied. The rate of initiation by a mixture of triethylborane and tert‐butyl peroxide was found to be first‐order in peroxide. The order in triethylborane changes from one at low triethylborane/peroxide to nearly zero at high triethylborane/peroxide. The possibility of a mechanism involving a fast reaction followed by a slow reaction that would initiate the polymerization is discussed.
Cationic polymerization behavior of hydroxystyrenes
Authors: Kato Masao 
Published: April 2003

AbstractSolution polymerizations of o‐, m‐ and p‐hydroxystyrene with boron trifluoride etherate were investigated. The results of infrared and ultraviolet spectroscopic investigations of the polymers thus obtained indicate that p‐hydroxystyrene polymer consisted mainly of the structure formed through the normal vinyl polymerization mechanism, whereas o‐ and m‐hydroxystyrene polymers contained considerable portions of the structures due to the reaction of the vinyl group with the phenol nucleus. The rate of polymerization and the intrinsic viscosity of the polymer decreased in the order p‐hydroxystyrene ≫ o‐hydroxystyrene > m‐hydroxystyrene. It was of interest that on the cationic polymerization only p‐hydroxystyrene gave polymer of high molecular weight. Plausible polymerization mechanisms were considered. Solid‐state polymerization of p‐hydroxystyrene at solid carbon dioxide temperature with the use of boron trifluoride etherate was also investigated. Appreciable polymerization occurred only at fairly high catalyst concentrations.
A novel method of metal ion removal and recovery from water by complex formation with polyelectrolytes
Authors: Jellinek H. H. G. , Luh Ming Dean 
Published: April 2003

AbstractA novel method of metal removal and recovery and recovery is described. This method may be useful in connection with various types of water pollution. It is based on the fact that metal ions form water‐soluble complexes with water‐soluble polyelectrolytes, such as polyacids. These complexes can be precipitated with polybases and the metal can be recovered by treating the precipitate with mineral acid. The remaining polymer complex can be used again for further precipitation. Experiments with Cu2+ and Co2+ ions are given in some detail; general observations concerning other cases are included.
Investigations on aromatic polyesters with polynaphthalene systems in the main chain. I. Low‐temperature solution polycondensation
Authors: Jedlińaski Zbigniew , Sek Danuta 
Published: April 2003

AbstractA series of aromatic polyesters has been prepared by low‐temperature solution polycondensation of derivatives of dihydroxydinaphthyl or dihydroxydinaphthylmethane with terephthaloyl chloride. The chemical, physical, and thermal properties of some polyesters have been investigated. Some of the polyesters obtained have high melting temperatures (340–420°C) and very good thermal resistance. In spite of their high melting temperatures some polymers give solutions in organic solvents which make it possible to produce films and coatings with good dielectric and mechanical properties and with a relatively high thermal resistance.
Chain transfer constants for vinyl monomers polymerized in methyl oleate and methyl stearate
Authors: Jordan Edmund F. , Artymyshyn Bohdan , Wrigley A. N. 
Published: April 2003

AbstractChain transfer constants were obtained for styrene, methyl methacrylate, methyl acrylate and vinyl acetate, polymerized in methyl oleate and methyl stearate at 60°C. Transfer constants increased in the order: methyl methacrylate < styrene < methyl acrylate ≪ vinyl acetate in both solvents. Average values of the transfer parameters were: for methyl oleate, Qtr = 2.04 × 10−4, etr = 1.08; for methyl stearate, Qtr = 0.373 × 10−4, etr = 1.01. Indication that polar species predominate in the transition state is supported by the observed order of reactivity. The usual rate dependence appeared to be followed by all of the monomers except vinyl acetate, which was retarded, severely in methyl oleate. Transfer in methyl oleate was about 5.8 times greater than that found in methyl stearate for these four monomers. The internal allylic double bond of methyl oleate had about the same reactivity in transfer as had the terminal unsaturation in N‐allylstearamide at 90°C. Rough estimates were obtained of the monomer transfer constants for the long side‐chain homologs of these four monomers from the respective monomer transfer constants and the experimental transfer constants, corrected for transfer to the labile groups of the solvent. It was concluded that the rate of polymerization would determine in large measure the degree of polymerization for the reactive 18‐carbon homologs but that the molecular weight of poly(vinyl stearate) and (oleate) will be regulated primarily by transfer to monomer.
Reaction mechanism of the alternating copolymerization of aziridines with cyclic imides
Authors: Kagiya Tsutomu , Adachi Teruho , Fukui Kenichi 
Published: April 2003

AbstractThe copolymerizations of N‐substituted aziridines and cyclic imide were studied. N‐Ethylsuccinimide copolymerized with ethylenimine, but N‐ethylethylenimine did not copolymerize with succinimide and N‐ethylsuccinimide without catalyst. The effect of additives on the copolymerization of ethylenimine with succinimide and that of N‐ethylethylenimine with succinimide and N‐ethylsuccinimide was also examined. The rate of copolymerization of ethylenimine with succinimide was accelerated by the addition of N‐acetylethylenimine or water. The copolymerization of N‐ethylethylenimine with succinimide was initiated only by water, but N‐ethylethylenimine did not copolymerize with N‐ethylsuccinimide in the presence of water. Gas evolved on heating the copolymer of ethylenimine and succinimide was analyzed and confirmed to be ammonia. On the basis of these results the reaction mechanisms of the copolymerization of ethylenimine with succinimide or N‐ethylsuccinimide and of N‐ethylethylenimine with succinimide initiated by water are discussed.
Structural study of alternating copolymerization of aziridines with cyclic imide
Authors: Kagiya Tsutomu , Izu Masatsugu , Adachi Teruho , Fukui Kenichi 
Published: April 2003

AbstractThe structures of copolymers of aziridines with cyclic imides were determined by means of infrared spectrometry, paper electrophoresis of the hydrolyzate, and NMR spectrometry. The structure of the repeating unit in the copolymer of ethylenimine with succinimide was \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} ({\rm CH}_2 {\rm CH}_2 {\rm NHCOCH}_2 {\rm CH}_2 {\rm CONH}\rlap{--} ) $\end{document}. The endgroups of the copolymer were N‐acylethylenimine ring, N‐substituted succinimide ring, and primary amide group. The copolymer of ethylenimine with N‐ethylsuccinimide had the repeating unit of \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH}_2 {\rm CH}_2 {\rm NHCOCH}_2 {\rm CH}_2 {\rm CON}({\rm C}_2 {\rm H}_5 )\rlap{--} ] $\end{document} and the endgroups of N‐acylethylenimine and N‐substituted succinimide ring. N‐Ethylethylenimine did not copolymerize with succinimide, but in the presence of water, the reaction occurred to give an amorphous polymer. This copolymer had the repeating unit \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH}_2 {\rm CH}_2 {\rm NHCOCH}_2 {\rm CH}_2 {\rm CON}({\rm C}_2 {\rm H}_5 )\rlap{--} ] $\end{document} and the endgroups were N‐substituted succinimide ring and amine group but not N‐acylethylenimine ring. On the basis of this structural information, the initiation reaction was discussed.