bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some products of interaction of p‐benzoquinone with styrene
Authors: Ghanem N. A. , Yehia A. A. , Rizk Nadia A. 
Published: April 2003

AbstractUsing equimolar concentrations of p‐benzoquinone and styrene at 100°C, a compound consisting of one molecule of benzoquinone, one molecule of hydroquinone and one molecule of styrene was separated from the complex reaction mixture in a small yield. Quinhydrone was separated at short reaction time and hydroquinone at prolonged reaction times. Reaction mechanisms for the formation of these compounds are proposed.Solvent extraction, fractional precipitation, thin layer chromatography, IR and UV spectrophotometry, elementary analysis, and molecular weight determination were applied for separation and identification.
NMR studies of polymer solutions. VII. Effects of chain length on polymer NMR measurements
Authors: Liu Kang‐Jen 
Published: April 2003

AbstractThe strong short‐range near‐neighbor effect on the NMR spectra of poly(dimethyl siloxanes) as a function of chain length in bulk as well as in solution was further demonstrated. The internal methyl groups of the polymer are distinguishable as the chain length n ≥ 5. A main polymer NMR peak appears for poly(dimethyl siloxane) only when n ≥ 7. In addition to the short range effect on the NMR peaks of the „near‐end groups”︁ of a polymer, we have also shown that the main polymer NMR peaks of poly(dimethyl siloxane) and poly(ethylene glycol) are also affected by chain length in certain aromatic solvent media. This is due to the effect of chain length on the solvation behavior of the main polymer segments, and it may be considered as a long range effect. Both these short and long range effects on the NMR absorption peaks and the bandwidths have been discussed.
Cationic copolymerization of cyclic formals and vinyl ethers
Authors: Okada Masahiko , Yamashita Yuya 
Published: April 2003

AbstractCopolymerizations of 1.3‐dioxepane with isobutyl vinyl ether and of 1.3.6‐trioxocane with 2‐chloroethyl vinyl ether were carried out in methylene chloride using boron fluoride ethyl ether complex as a catalyst. NMR and methanolysis studies on the copolymers have shown that both monomer units are not randomly distributed in these copolymers but that these monomers form blocks of relatively long sequences.
Imidazole catalyses in aqueous systems. II. Inhibition studies on the enzyme‐like catalysis in the hydrolysis of a phenyl ester by an imidazole‐containing copolymer
Authors: Kunitake Toyoki , Shimada Fumiko , Aso Chuji 
Published: April 2003

AbstractInhibitory actions of several organic compounds on the enzyme‐like catalysis of a water‐soluble copolymer of 1‐vinyl‐2‐methylimidazole and N‐vinylpyrrolidone were studied in the hydrolysis of 3‐nitro‐4‐acetoxybenzoic acid. The hydrolyses were carried out in 1 M KCl at 30°C, pH 8.0, using a pH‐stat system. The inhibitions were analyzed by the LINEWEAVER‐BURK plotting of the MICHAELIS‐MENTEN equation as in enzymatic reactions. Benzyl alcohol, the 2.4‐dinitrophenolate anion, and dioxane competitively inhibited the enzyme‐like catalysis of the polymer catalyst, Ki (inhibition constant) being 110, 42, and 1000 (10−3 mole · 1−1), respectively. Acetone showed a mixed‐type (competitive plus noncompetitive) inhibition. The rate‐depressing effect of the product, the dianion form of 3‐nitro‐4‐hydroxybenzoic acid, could not be included in the common category of inhibition. Observation of these competitive and other inhibitions and a comparison of Ki's supported the validity of the enzyme‐like catalysis proposed for the imidazole‐containing copolymer and endorsed the previous proposition that the catalytic site was bound to a substrate or an inhibitor by mainly hydrophobic forces.
Über die bildung freier radikale in röntgenbestrahlten vinylmercaptan/vinylpyrrolidon‐copolymeren
Authors: Mönig Von H. , Ringsdorf H. 
Published: April 2003

AbstractDie Bildung und das Verhalten von strahleninduzierten Radikalen in Polyvinylmercaptan und Copolymeren aus Vinylmercaptan und Vinylpyrrolidon wurden mit Hilfe der ESR‐Spektroskopie untersucht. In allen Polymeren konnten RS•‐Radikale nachgewiesen werden, die im Fall der Copolymeren teilweise durch Kettenübertragung entstehen. Die Copolymeren werden nur schwach bzw. nicht vernetzt, was auf einen Schutz‐ bzw. Regenerationseffekt der Vinylpyrrolidon‐Einheiten durch die Mercaptogruppen zurückgeführt wird.
Die thermische diffusion von polystyrol in verschiedenen lösungsmitteln
Authors: Meyerhoff Von G. , Rauch B. 
Published: April 2003

AbstractEs wird über Messungen von thermischen Diffusionskoeffizienten und LUDWIG‐SORET‐Koeffizienten von Polystyrol in den Lösungsmitteln Toluol, Methyläthylketon, Butylacetat und Cyclohexan berichtet. Es zeigte sich, daß der rein thermisch bedingte Diffusionsprozeß in Butylacetat und im Θ‐Lösungsmittel Cyclohexan unabhängig vom Molekulargewicht ist, wie as für Toluol bereits früher nachgewiesen werden konnte.Für Methyläthylketon wurde eine schwache, aber deutliche Abhängigkeit von D' vom Molekulargewicht zu D' ∼ M−0,12 gefunden. Bemerkenswerterweise verhalten sich die beiden in Bezug auf Polystyrol thermodynamisch sehr ähnlichen Lösungsmittel Butylacetat und Methyläthylketon in dieser Hinsicht sehr verschieden.
The intrinsic viscosity‐molecular weight relationship for polypropylene
Authors: Yamaguchi Kinya 
Published: April 2003

AbstractMeasurements of intrinsic viscosity in decalin at 135°C and light scattering in α‐chloronaphthalene at 145°C were performed for several polypropylene fractions of molecular weight ranging up to 2.106. The specific refractive index increment at 436 mμ for the α‐chloronaphthalene solution was found to be −0.231 ml/g, which is considerably higher than those reported by CHIANG and others authors. However, no significant disparity is observed between the results of light scattering measurements by CHIANG and the present author. The intrinsic viscosity‐molecular weight relationship obtained is: [η] = 1.15·10−4 M, which is in good agreement with that reported by KINSINGER and HUGHES. This relationship is also compared with those of other authors observed at different conditions of viscosity measurements.
Alternative copolymerization of vinyl sulfides with maleic anhydride. III. Alternative copolymerization
Authors: Otsu Takayuki , Inoue Hiroshi 
Published: April 2003

AbstractEthyl vinyl sulfide (EVS) and phenyl vinyl sulfide (PVS) were found to undergo alternative copolymerization with maleic anhydride (MAn) even in the absence of radical initiators. It is noted that both the rates and the reduced viscosities in these alternative copolymerization show a maximum at 50 mole‐% comonomer mixture, anticipating that a 1 : 1 charge transfer complex is formed preceding polymerization. From spectroscopic studies, it was also observed that the formation of such a complex between vinyl sulfide and MAn was confirmed, but their equilibrium constants were quite small, i.e. 0.090 l./mole for PVS‐MAn in CHCl3 and 0.035 l./mole for EVS‐MAn in CH2Cl2 at room temperature. The mechanism of these alternative copolymerizations is discussed.
Growth of polyoxymethylene crystals in the course of the polymerization of trioxane in solution
Authors: Iguchi M. , Kanetsuna H. , Kawai T. 
Published: April 2003

AbstractIn order to pursue the possibility of the extended chain crystals of polymers formed in the course of polymerization, the cationic polymerization of trioxane in cyclohexane has been studied. The polymer, polyoxymethylene, was obtained in the form of a unique single crystal. From the morphological and physical studies of the resultant polymers as well as the kinetical studies of the polymerization, it has been revealed that long, needle‐like nuclei formed in the beginning of the polymerization grew into feather‐like platelets with twin habit. The degree of crystallinity of the nascent polymer was essentially 100% in terms of their densities. The molecular chains were fully extended and regularly aligned in the direction of the crystal growth. The growth of the crystal occurred as the polymerization proceeded. Thus it is considered that the crystal grows quite successively to the propagation of the chains through direct addition of the monomer molecules onto the reactive chain ends which are aligned two‐dimensionally on the growing surface of the crystal. The molecular length of the nascent polymer estimated from the solution viscosity, however, did not agree with the crystal dimensions measured in the direction of the molecular orientation, the former being rather small. The above results are explained in terms of the chain‐transfer reaction and the catalytic decomposition of the polymer chain.
Mechanism of thermal initiation in styrene polymerization1
Authors: Brown Weldon G. 
Published: April 2003

AbstractNew observations on the thermal polymerization of pure styrene at 130°C refute an earlier claim by MÜLLER that 1‐phenyltetralin is the major dimeric product. The principal dimeric products are cis‐ and trans‐1.2‐diphenylcyclobutane in a 1:2 ratio with relatively minor amounts of 1‐phenyltetralin, 1.3‐diphenylbutene, and 1‐phenyl‐1.2‐dihydronaphthalene. Data are also given for the dimers formed at 85°C and for the dimers isolated from a fully cured (180°C) polystyrene the significance of differences in minor constituent yields is assessed. MAYO's basic postulate of radical pair production by reaction of a DIELS‐ALDER type dimer with styrene is the starting point for a more extended reaction scheme in which cage reactions form minor dimeric and trimeric products in compeßition with chain initiation.
On the partially free draining effect in the intrinsic viscosity and sedimentation coefficient of cellulose nitrate solution
Authors: Kamide Kenji 
Published: April 2003

AbstractThe partially free draining effect on intrinsic viscosity, sedimentation and diffusion constant was evaluated for cellulose nitrate solution. The methods used in this study involve the analysis of (a) parameters in the KUHN‐MARK‐HOUWINK‐SAKURADA equation, (b) intrinsic viscosity [η] and concentration dependence of sedimentation coefficient ks, (c) [η], ks, molecular weight M, and second virial coefficient A2, (d) molecular weight dependence of sedimentation constant and the exponent a in the KUHN‐MARK‐HOUWINK‐SAKURADA equation, (e) a and molecular weight dependence of diffusion constant, (f) a and dependence of [η] on radius of gyration of a polymer chain R, (g) a and molecular weight dependence of R, (h) [η], M, R, and the linear expansion factor α, (i) [η], M, and A2. Draining parameters thus obtained, such as X, ν(X), and Δ which were defined in the theories of KURATA‐YAMAKAWA and KAWAI‐KAMIDE, are compared with those in literature. Although the methods used here have been derived from different theoretical bases using different approximations, ν(X) was evaluated as 0.3 ± 0.1 for cellulose nitrate with nitrogen content of 12 to 14%, irrespectively of the method used. This indicates that the draining effect can not be ignored, in other words, the intrinsic viscosity and sedimentation data can not be interpreted reasonably by the excluded volume theories, without taking into account the draining effect.
Crystallization of A‐B‐A type block copolymers of poly(ethylene oxide) and poly(α‐methyl styrene) from dilute solutions
Authors: Kawai Tōru , Shiozaki Shigeru , Sonoda Shinji , Nakagawa Hideaki , Matsumoto Takako , Maeda Hirokuni 
Published: April 2003

AbstractIn order to examine the possibilities of a heterogeneous fold structure proposed previously, in which large irregular loops are incorporated in regular sharply reentrant folds on the surface of polymer single crystals and of the molecular ties which connect lamellae in multilayer crystals, the morphologies of the solution grown crystals of the A‐B‐A type block copolymers of poly(ethylene oxide) (A) and poly(α‐methyl styrene) (B) have been studied mainly as a function of polymer concentration. The range of the content of polyethylene oxide (PEO) was from 0.551 to 0.860, the molecular weight of each sequence being in the order of 104 to 105. The solvents used were ethylbenzene, xylene, and isoamylacetate. It was found that the copolymers having the PEO contents beyond 0.643 crystallized from dilute solution (0.1 to 0.25%) into the form of square tablets, similar to the PEO single crystals. Electron micrographs of these crystals revealed that poly(α‐methyl styrene) chains were excluded from the crystalline part and deposited on the surface of the crystals during chain‐folding crystallization and long loops thus formed aggregated in the solution or on drying the crystals in a manner depending on the solvents used. When the polymer concentration was increased to 0.5%, irregularly shaped, multilayer crystals were formed where a number of holes were found on their surfaces, suggesting that the frequency of the formation of tie molecules increased rapidly with increasing concentration. Evidences have been supplied for the formation of the long loops on the surfaces of lamellar crystals and of inter‐lamellar tie molecules in the chain‐folding crystallization.
NMR studies on the microstructure of copolymers of 1.3‐dioxolane and 1.3.5‐trioxane
Authors: Yamashita Yuya , Asakura Toshiyuki , Okada Masahiko , Ito Koichi 
Published: April 2003

AbstractThe sequence distributions of the formal (OCH2) and ethylene oxide (OCH2CH2) units in copolymers of 1.3‐dioxolane (DOL) and 1.3.5‐trioxane (TOX) prepared under various polymerization conditions were determined by NMR. The results can be largely explained by a random copolymerization process including depolymerization, in which DOL is kinetically more reactive, but its incorporation is thermodynamically less favourable than that of TOX. However, in the later stages of the reactions the microstructure of the copolymer changes to give longer polyoxymethylene sequences, which produces very complicated thermodynamic problems.
Investigation on the interaction mechanism between the electrochemically produced benzophenone radical‐anions and various monomers
Authors: Mengoli Giuliano , Vidotto Graziano 
Published: April 2003

AbstractThe decay caused by the interaction between methacrylonitrile, methylmethacrylate, acrylonitrile, and methylacrylate and benzophenone radical‐anions produced through electrolytical reduction of benzophenone in dimethylformamide in the presence of tetraethyl‐ammonium perchlorate as background electrolyte, has been investigated at various temperatures by using the polarographic and amperometric techniques. Owing to the interaction with the monomers, the benzophenone radical‐anions fully reoxidate to benzophenone. Moreover, decay rates will depend on the square radical‐anions and first power monomer concentration and are inversely proportional to the concentration of unaltered benzophenone present in the system.The experimental results are interpreted on the basis of a kinetic scheme which comprises the dismutation of benzophenone radical‐anions to dianions and benzophenone, and subsequent electronic transfer from dianions to monomers.
Herstellung und eigenschaften von photometrisch quantitativ bestimmbaren, bei der polymerisation vernetzenden bisacrylsäureestern und von bispropionsäureestern als modellverbindungen
Authors: Kämmerer Von Hermann , Mück Karl‐Friedrich 
Published: April 2003

AbstractEs wurden 6 Bisacrylsäureester hergestellt, die photometrisch quantitativ bestimmbare Strukturgruppen enthalten. Angaben zur Löslichkeit, IR‐, UV‐Absorptions‐ und 1H‐NMR‐Spektren dienten zur Charakterisierung der Verbindungen. Daneben wurden Dipropionsäureester synthetisiert, die sich durch Austausch der Acrylsäure‐ gegen die Propionsäurereste von den Bisacrylsäureestern ableiten. Verdünnte Lösungen der Bisacrylsäure‐ und Dipropionsäureester folgen im Bereich von 250–450 mμ dem BOUGUER‐LAMBERT‐BEER‐schen Gestz. Aus den Ergebnissen der Homopolymerisation der Bisacrylsäureester läßt sich schließen, welche Ester für eine einfache photometrische Analyse schwach vernetzter Copolymerer in Betracht kommen.
Copolymerization of carbon dioxide and epoxide with organometallic compounds
Authors: Inoue Shohei , Koinuma Hideomi , Tsuruta Teiji 
Published: April 2003

AbstractAttempts to copolymerize carbon dioxide with epoxide led us to the first success in using carbon dioxide as a direct starting material for synthesizing high polymers. Some organometallic catalyst systems were found to catalyze the alternate copolymerization of carbon dioxide and epoxide, resulting in the formation of polycarbonates, the structures of which were confirmed with the aid of IR, NMR and elemental analysis. Diethylzinc‐water system produced a methanol insoluble aliphatic polycarbonate of much higher molecular weight than that produced by polycondensation. Thermal properties of the methanol insoluble polycarbonate were studied by differential thermal analysis and thermogravimetric analysis.
Polymerization mechanism of N‐carboxy‐α‐amino acid anhydride by organometallic compounds. II.. Reaction with organozinc compounds
Authors: Makino Tetsuya , Inoue Shohei , Tsuruta Teiji 
Published: April 2003

AbstractReactions of N‐carboxy‐α‐amino acid anhydride (NCA) with dialkylzinc or related organozinc compounds were studied to elucidate the polymerization mechanism of NCA by dialkylzinc as initiator.The first stage of initiation reaction is a hydrogen abstraction reaction of dialkylzinc from NH group of α‐amino acid NCA resulting in the formation of an activated NCA. The second stage of initiation is a reaction between two molecules of the activated NCA forming a zinc carbamate group.Propagation reaction is a carbonyl addition of the zinc carbamate group to the activated NCA to form a mixed anhydride which changes into an amide group releasing carbon dioxide.Regeneration of the activated NCA is supposed to be done by the reaction of free α‐amino acid NCA with the zinc atom bonded to nitrogen atom at the growing chain end.
Crystallization of cellulose from dilute solutions
Authors: Maeda Hirokuni , Kawada Haruo , Kawai Tōru 
Published: April 2003

AbstractCellulose samples having a degree of polymerization (P) of 400, 200, 100, and 50 were crystallized isothermally from dilute solutions of aqueous sodium hydroxide and from cellulose xanthate solutions. Observation of the suspension under an optical microscope revealed that in most cases various shapes of huge lamellae in the order of 10 to 50μ were formed. These lamellae could easily be disintegrated by ultrasonic cavitation and under an electron microscope they were seen as fibrous sheets. In all the cases studied, the lengths of the fibrils were equivalent to or longer than the fully extended molecular length. The huge lamellae viewed under an optical microscope are considered to be loosely packed aggregates of the fibrils. In view of the low crystallinity found in these fibrils, the fringed micelle model seems rather preferable to the extended chain crystals. Viscometric measurements showed that the induction period, where reduced viscosity decreased or did not change, was followed by the pre‐crystallization stage which was manifested by a sudden increase, and then crystallization started as revealed by a rapid decrease in the reduced viscosity. This implies that cellulose chains were stiffened by the formation of intramolecular hydrogen bonds before the intermolecular crystallization started. If the formation of the intramolecular hydrogen bonds prior to a regular ordering of the chains in a lattice was avoided, therefore, it is anticipated that cellulose crystallizes in the form of chain folded lamellae. This was actually achieved by using an aqueous solution of equal moles of sodium hydroxide and methanol as the solvent. In this case, the reduced viscosity did not increase appreciably and dropped as the crystallization started. Namely, stiffening of the cellulose chains did not occur in the pre‐crystallization stage. The electron microscopy revealed that the crystals formed were lamellar in this case. The size of the lamellae was in the range of 0.5 to 5μ, and their thickness was in the order of 80 to 120 Å. Molecular length of cellulose used being ca. 2000 Å, the chains must be folded in these crystals.
Sur les systèmes catalytiques TiCl4‐AlR3. V. Addition de l'alcoyl‐aluminium en deux étapes
Authors: Laputte Par Robert , Guyot Alain 
Published: April 2003

AbstractDes systèmes catalytiques TiCl4‐AIR3 préparés de façon à obtenir l'optimum de l'ativité polymérisante vis‐à‐vis du butène‐1, sont modifiés par addition in situ d'une nouvelle charge d'un alcoyl‐aluminium éventuellement différent du composé initial. Cette addition provoque des changements importants des activités polymérisante et isomérisante, qui sont discutés en fonction de la variation de composition du solide catalytique obtenue.
Oxidative polymerization of aromatic amines in aqueous solution of iron chelate
Authors: Tsuchida Eishun , Kaneko Masao , Kurimura Yoshimi 
Published: April 2003

AbstractAromatic amines, such as p‐phenylenediamine (PD) or p‐aminophenol (AP) have been found to polymerize oxidatively at room temperature, catalyzed by ferric chelates, e.g., the Fe(III)‐salt of ethylenediaminetetraacetic acid, in aqueous solution. The polymers from PD or AP are black and do not melt below 300°C. They have paramagnetic and electroconductive properties (ca. 10−10 Ω−1 ċ cm−1). They have also reversible oxidation and reduction properties; in methanolic solution the polymer is reduced by an aqueous sodium hydrosulfite solution, resulting a light yellow solution, which is re‐oxidized by air to the original black polymer. The structures of the polymers are also presented.
Copolymerization of various isocyanates with ethylene oxide
Authors: Harada Kunihiro , Deguchi Atsushi , Furukawa Junji , Yamashita Shinzo 
Published: April 2003

AbstractCopolymerization of various monoisocyanates with ethylene oxide was attempted in relation to the alternate copolymerization of phenyl isocyanate with ethylene oxide by triethylaluminum catalyst. It was found that aliphatic and alicyclic isocyanates are not copolymerizable at all while many of aromatic isocyanates give the copolymer. The copolymer obtained was supposed to be alternate one. As to the substituted phenyl isocyanates, it was shown that ortho‐substituted isocyanates give the copolymer in high yield, with one exception: o‐anisyl isocyanate. There is no relation between the copolymer yields and HAMMETT'S substituent constants. These results suggest that triethylaluminum may preferentially coordinate with the oxygen atom rather with the nitrogen of the isocyanate group and that the coordination of the catalyst with the substituent may also occur. These expectations were confirmed by the infrared technique and the copolymer structure.
Contact interactions of polydimethylsiloxane and its low oligomers with solvents
Authors: Morimoto Satoshi 
Published: April 2003

AbstractThe contact interaction parameters X12 for polydimethylsiloxane (PDS) and for some low oligomers with various solvents were calculated from the data obtained from the heat of mixing at infinite dilution using the statistical thermodynamic theory of liquid mixtures developed by FLORY et al.. Comparing these values with those of polyisobutylene (PIB), the results were explained by the difference of diameter between both polymer segments, by the existence of bonded oxygen in the PDS polymers, and by the difference of flexibility between the polymer and the long chain molecular solvent.
Thermal oxidative stability of some poly(phosphonylureas)
Authors: Carraher Charles E. , Krueger Calvin W. 
Published: April 2003

AbstractThe thermal oxidative stability of poly(phosphonylureas) of the below from was studied.
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The products show significantly better thermal stability than their carbon counterparts. The product where R is C6H5— and R′ is 1.3‐C6H4‐ has only 10% weight loss at 400°C and 40% weight loss at 600°C. The thermal degradation of the poly(phosphonylureas) followed using infrared spectroscopy. Possible initial degradation sites are discussed.