bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of vinyl compounds with heterocyclic groups. IV. Thermal polymerization of 2‐vinylthiophene
Authors: Aso C. , Kunitake T. , Shinsenji M. , Miyazaki H. 
Published: April 2003

Abstract2‐Vinylthiophene was found to undergo thermal polymerization. With benzene as diluent, the overall rate of polymerization was proportional to the 2.5 power of monomer concentration, suggesting that the thermal initiation is a termolecular process. The following Arrhenius equation was obtained from the polymerization data for the range 55–100°C:

The activation energy of the thermal initiation was estimated to be 28.2 kcal/mole, which was similar to those values obtained for styrene and 2‐vinylfuran. When a dilute solution of the monomer in bromobenzene was heated in an ampoule at 151°C, a dimer, mp 82°C, was obtained in a good yield. The spectroscopic data indicated that the dimer was a Diels‐Alder type adduct. The initiation of the thermal polymerization was considered to involve hydrogen abstraction by monomer from the Diels‐Alder dimer, in common with the initiation of other vinylaromatic monomers.
Stereospecific polymerization of benzyl vinyl ether by BF3·OEt2
Authors: Yuki Heimei , Hatada Koichi , Ota Koji , Kinoshita Ikuya , Murahashi Shunsuke , Ono Katsuhiro , Ito Yoshiyuki 
Published: April 2003

AbstractPolymerization of benzyl vinyl ether was carried out by BF3·OEt2, and the effects of polymerization conditions on the stereoregularity of the polymer were studied by NMR analysis. The polymerization at −78°C in toluene gave a highly isotactic polymer. The isotacticity of the polymer was independent of the catalyst concentration but increased with a decrease in the initial monomer concentration and decreased slightly on raising the reaction temperature. When the polymerizations were carried out in toluene—nitroethane mixtures, a gradual decrease in the isotacticity and a rapid decrease in the molecular weight of the polymer were observed with increasing nitroethane in the solvent. The molecular weight of the polymer was almost constant, regardless of the catalyst concentration, and increased with increasing initial monomer concentration and decreasing polymerization temperature. When the polymerization was performed in toluene at −78°C with a small amount of water or benzyl alcohol, a linear relationship was found between the reciprocal DP of the polymer and water or benzylalcohol concentration. The mechanisms of the initiation reaction and the stereoregulation in the polymerization were also discussed.
Polymerization of β‐cyanopropionaldehyde. VI. Anionic polymerization initiated by aromatic hydrocarbon—sodium complexes
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi 
Published: April 2003

AbstractFurther investigation on an anionic polymerization of β‐cyanopropionaldehyde was made with use of polystyryl—disodium, naphthalene—sodium, and tetraphenylethylenedisodium complexes as initiators. Styrene—β‐cyanopropionaldehyde block copolymer was separated from the gross polymer obtained by the polymerization of β‐cyanopropionaldehyde with polystyryl—sodium. The polymerization initiated by naphthalene—sodium and tetraphenylethylene—disodium complexes resulted in the formation of an aldol condensation‐type product having a low molecular weight. It was found that initiators of weaker basicity may start the carbonyl polymerization, whereas those of stronger basicity cause the aldol condensation of β‐cyanopropionaldehyde through the withdrawal of proton from the monomer.
Untersuchungen zur molekulargewichtsverteilung von polyäthylenterephthalat
Authors: Gehrke Klaus , Reinisch Gerhard 
Published: April 2003

AbstractThe molecular weight distribution of carefully prepared thermostabilized poly(ethylene terephthalate) was determined immediately after polycondensation in vacuo (P̄n = 121) and after the melt was stirred at 280°C for 5.5 hr under nitrogen (P̄n = 123). The fractionation was carried out by successive precipitation in liquid phases. The samples were separated into 25 fractions including refractionation. The Flory distribution was observed in all samples.
Aromatic copolyimide–amides II
Authors: Wrasidlo W. , Augl J. M. 
Published: April 2003

AbstractSix thermally stable polyimide‐co‐amides have been synthesized from sulfurylbis[N‐(4′‐phenylene)‐4‐(chloroformyl)‐phthalimide] and various aromatic diamines. Linear, high molecular weight final polymers were obtained by one step low‐temperature solution condensations in dimethylacetamide. Thermal properties such as glass transition and polymer decomposition temperatures and solution properties such as viscosities and solubilities varied significantly with polymer structure. Tough, flexible films of these polymers were cast from solution. The thermal‐oxidative stabilities of films were strongly dependent on structure, solvents used, and impurities present.
Mechanism of decoloration by solvent of thermally degraded poly(vinyl chloride)
Authors: Matsumoto Tsunetaka , Mune Isao , Watatani Seiji 
Published: April 2003

AbstractThe mechanism of decoloration of thermally degraded poly(vinyl chloride (PVC)) by solvents has been investigated systematically. The main results obtained are as follows. Good solvents for PVC, especially tetrahydrofuran, methyl ethyl ketone, and dioxane are effective for decoloration. The solvent peroxide which is formed by autoxidation of solvent contributes to decoloration. The number of double bonds in degraded PVC decreases as the decoloration proceeds and at the same time the solvent peroxide existing in solvent is consumed. Moreover, the existence of solvent fragments in decolored PVC is recognized. From these results, it is most reasonable to conclude that the decoloration mechanism is as follows: the solvent partially is changed to a solvent peroxide by autoxidation, and the solvent peroxide reacts with polyene double bonds of degraded PVC and breaks down conjugated double bonds, and consequently degraded PVC is decolored.
Grafting of maleic anhydride on polyethylene. III. Influence of polyethylene concentration on the course of the reaction in a homogeneous medium
Authors: Porejko Stanisław , Gabara Włodżimierz , Błażejewicz Teresa , Łȩcka Maria 
Published: April 2003

AbstractThe effect of the polymer concentration on the grafting of maleic anhydride on polyethylene was studied at different temperatures and at different monomer and initiator concentration. The character of the curves obtained suggests the importance of the termination reactions and the appearance of the gel effect at higher polymer concentrations.
Copolymers of modified starches with polyacrylonitrile
Authors: Fanta George F. , Burr Robert C. , Russell C. R. , Rist C. E. 
Published: April 2003

AbstractA study was made of the ceric ammonium nitrate‐initiated graft polymerization of acrylonitrile (AN) onto a number of modified starches that had been reduced in molecular weight by either acid, hypochlorite, or enzyme treatment. With highly soluble starches, much of the starting material was recovered as ungrafted carbohydrate, and the reaction product was largely dimethylformamide‐soluble polymer with a high polyacrylonitrile (PAN) content. The molecular weight of grafted PAN was lower when the modified starches existed as granules in water dispersion; however, heating (60°C) an aqueous slurry of an acid‐modified corn starch (with intact granules) before the reaction had relatively little effect on the composition of the copolymer. Decreasing the concentrations in water of modified starch and AN resulted in more frequent and lower molecular weight grafts of PAN. Aqueous methanol as a reaction medium for an acid‐modified starch with intact granules led to more frequent grafting of lower molecular weight PAN than when water alone was used. The number of grafted chains, however, was fewer than found with unmodified wheat starch under comparable conditions. A modified starch with the granule structure completely broken down gave no detectable reaction in aqueous methanol.
Thermogravitational effect in macromolecular solutions
Authors: Gaeta F. S. , Cursio N. M. 
Published: April 2003

AbstractWe have investigated in a thermogravitational apparatus the behavior of solutions containing macromolecular solutes and of suspensions of ultramicroscopic particles such as viruses and ribosomes. We have obtained very high separation ratios with all the solutes studied, the value of the separation being characteristic of each solution. The reproducibility of the results is good, and the dependence on the geometrical and physical parameters involved fits the predictions of the phenomenological theory. Our results prove that fractionation of very high molecular weight particles is feasible by this method, and also that the characterization of the macromolecular species and the determination of the mass and shape of the particles of the solute seem to be within the possibilities of the thermogravitational method when this is applied to very high molecular weight materials.
Sulfur modification of polyethylene surfaces. III. Frustrated multiple internal reflection spectroscopy of sulfonated polyethylene surfaces
Authors: Olsen Douglas A. , Osteraas A. Jean 
Published: April 2003

AbstractThe previous publications of this series show by indirect means that atomic sulfur inserts into the carbon—hydrogen bonds of polyethylene surfaces. In this study, frustrated multiple internal reflection (FMIR) spectroscopy was used to obtain direct evidence of the nature of the surface groups of the modified polyethylene. The FMIR spectra of surfaces consisting of the products of sulfonic acid groups were virtually identical, regardless of whether the original sulfonic acid surface had been prepared by direct sulfonation or by oxidation of surface thiol groups. The latter groups resulted from the insertion of atomic sulfur into the carbon—hydrogen bonds of the surface. These results establish that sulfur is indeed inserted into polyethylene surfaces.
Stereospecific polymerization of o‐methoxystyrene by anionic initiators
Authors: Yuki Heimei , Okamoto Yoshio , Kuwae Yoshiteru , Hatada Koichi 
Published: April 2003

Abstracto‐Methoxystyrene was polymerized with n‐butyllithium (n‐BuLi), Na naphthalene, and K dispersion as initiators in tetrahydrofuran (THF) and toluene. The stereoregularity of the polymer was investigated by means of the NMR spectroscopy. The methoxy resonance of the spectrum split into ten components due to the tactic pentads. It was found by x‐ray examination that the polymer obtained by n‐BuLi in toluene at −45°C was crystalline and highly isotactic. In THF, the stereospecificity of the polymerization was independent of the initiator, and the isotacticity of the polymer increased with increasing reaction temperature. In toluene, the stereospecificity depended on the initiator; i.e., n‐BuLi gave a polymer with higher isotacticity than that given by phenylsodium. The fraction of isotactic triad of the polymer obtained by n‐BuLi in toluene at −78°C was more than 90%, but 50% at 50°C. The presence of ca. 1% THF in toluene led to a steep decrease in the isotacticity even at −78°C. The tacticity of the polymer given by Na naphthalene was not affected by the existence of NaB(C6H5)4 in THF. The polymerization in THF could be explained by Bovey's “single σ” process, while a penultimate effect was observed in the polymerization by n‐BuLi in toluene.
Polymerization of methyl methacrylate under ultrasonic irradiation. Part IV. Effect of ultrasonic irradiation on Grignard catalyst and stereoregularity of the polymers produced in dioxane–tetrahydrofuran mixed solvent
Authors: Osawa Zenjiro , Kimura Takao , Kasuga Takao 
Published: April 2003

AbstractTwo series of polymerization of methyl methacrylate with Grignard reagent in dioxane—tetrahydrofuran mixed solvent was carried out under ultrasonic irradiation. In series A, catalyst was added to the mixture of monomer and solvent, and in series B, catalyst was previously mixed with solvent. The effect of ultrasonic irradiation on Grignard catalyst and the microstructure in reacting sites were discussed on the basis of the stereoregularity of the polymers produced. The stereoregularity of the polymers in series A was higher than that in series B. The effect of ultrasonic irradiation on the stereoregularity was completely reversed in series A and B and it increased in the former and decreased in the latter. It was, therefore, assumed that ultrasonic irradiation affected the microstructure in the reacting sites in series A, while it increased the relative amount of R2Mg which gave polymers with poor stereoregularity in series B.
Poly‐2,5‐distyrlpyrazine and its properties
Authors: Fujishige Shoei , Hasegawa Masaki 
Published: April 2003

AbstractFour possible structural models with novel steric character are proposed for poly‐2,5‐distyrylpyrazine: two of them are extended chains and the others are kinked coils. In order to prove the molecular characteristic of the new polymer, a procedure to solubilize the polymer into some organic solvents was developed. It was recognized by viscometry that no significant degradation of the polymer does occur during the preparation. The lack of the shear rate dependence of the dilute solution viscosities would seem to indicate that the polymer molecule in solution can be regarded as a chain, not extended linearly, but kinked randomly. The crystallization of the polymer proceeds only in the presence of a sufficient amount of the solvent which enables the polymer chains to move and crystallize. These imply that the possible structure of the polymer is constructed of 1,2‐ or 1,3‐cis type cyclobutane linkages with restricted rotation.
Metal coordination polymers. II. Molecular weight studies of beryllium phosphinate polymers in toluene
Authors: Slota P. J. , Grieve C. M. , Fetter N. R. , Bilbo A. J. 
Published: April 2003

AbstractThe number‐average molecular weights of beryllium 4‐biphenyl(phenyl)phosphinate, di‐n‐pentylphosphinate, di‐n‐heptylphosphinate, and trifluoromethyl(phenyl)phosphinate are degraded by the presence of water in toluene. It is proposed that easily hydrolyzable POP bonds contribute, in part, to the bonding of these polymers.
Polymerization of coordinated monomers. II. Stereoregulation in the free‐radical polymerization of methacrylonitrile–zinc chloride or methacrylonitrile–stannic chloride complexes
Authors: Hirai Hidefumi , Ikegami Tadashi , Makishima Shoji 
Published: April 2003

AbstractThe effect of complex formation on stereoregulation in free‐radical polymerization was studied. Complexes of methacrylonitrile with ZnCl2 and SnCl4 were prepared and their properties and structures examined. The complexes were polymerized by initiation of α,α′‐azobisisobutyronitrile or by irradiation with γ‐rays from a60Co source or ultraviolet rays either in solution or in bulk at various temperatures ranging from −78 to 100°C. The triad tacticities of the resulting polymethacrylonitrile were determined by converting it to poly(methyl methacrylate) for NMR spectroscopy. The radicals in complexed forms were studied by ESR spectroscopy with the polymerization system in toluene irradiated with ultraviolet rays at −120°C. The tacticities of the resulting polymers and their dependencies on the polymerization temperature were found to be characteristic of the complex species, i.e., the kind of metal chloride and the stoichiometry, being different from the tacticities and the dependencies, respectively, of the polymer obtained with pure methacrylonitrile. The 2:1 and the 1:1 complexes with SnCl4 were found to give an eleven‐line and a nine‐line spectrum, respectively. On the basis of the results of both the tacticities and the ESR spectra, it was estimated that the proportion of the intracomplex reaction was 40%, and that the probabilities of isotactic diad addition of intra‐ and intercomplex reaction were 0.70 and 0.48, respectively.
Combination of cellulosic materials and metallic ions
Authors: Ogiwara Yoshitaka , Kubota Hitoshi 
Published: April 2003

AbstractCellulosic materials (DP, SCP) and PVA fibers were treated with four kinds of metallic ions (Ca2+, Fe2+, Fe3+, Ce4+), and the adsorption behavior was studied to elucidate the manner in which the celluloses and the metallic ions were combined. The effects of treatment temperature, time, and concentration upon the amount of the metallic ions adsorbed were examined. With Ca2+ and Fe2+, the effects of such factors on the adsorption were slight, while with Fe3+ and Ce4+ the effects of time, temperature, and ion concentration were pronounced. Also, it was evident that the amount (molar) of equilibrium adsorption of Ca2+ or Fe2+ was approximately the same as the content of carboxyl groups in the cellulose sample, and the amount of equilibrium adsorption of Fe3+ or Ce4+ was approximately the same as that of total carbonyl group content. When the samples which had adsorbed these metallic ions were treated with 0.1N hydrochloric acid, the Ca2+ and Fe2+ were completely desorbed while about 80% of the adsorbed Fe3+ and Ce4+ remained. These results indicate that there are two types of combinations of cellulosic materials and metallic ions involved: one is thought to be an ionic bond, while the other is considered to be a chelate bond.
Investigation of the epoxide–carboxylic acid reaction in model compound and polymerization reactions
Authors: Alvey Francis B. 
Published: April 2003

AbstractThe reaction of epoxide and acid has been studied in the model reaction of bisphenol‐A diglycidyl ether and acetic acid with several base catalysts at 60, 95, and 115°C. The results suggest that no greater than 5% side reactions occur. A series of polyhydroxylester polymers were prepared from bisphenol‐A diglycidyl ether and adipic acid. The polymers gel rapidly upon heating at 200°C. Terpolymers of bisphenol‐A diglycidyl ether, bisphenol‐A, and azelaic acid were prepared. These also gel at 200°C when 50 mole‐% of the active hydrogen reactant is azelaic acid.
A contribution to the theory of the structural glass transition
Authors: Bartenev G. M. , Razumovskaya I. V. , Sanditov D. S. , Lukyanov I. A. 
Published: April 2003

AbstractThe equations characterizing the temperature dependence of the mobility of molecules in the glass transition region are compared and analysed. A relationship between the parameters of the relaxation theory of the glass transition and the concept of free volume is established. The Williams‐Landel‐Ferry equation is treated in terms of the relaxation theory of glass transition.
Polyaryleneimides of meso‐ and dl‐ 1,2,3,4‐butanetetracarboxylic acid dianhydrides
Authors: Loncrini D. F. , Witzel J. M. 
Published: April 2003

AbstractHigh molecular weight polyarylene amic acids have been prepared by reacting aromatic diamines with equimolar amounts of either meso‐or dl‐1,2,3,4‐butanetetracarboxylic acid dianhydride (TCBA) in organic polar solvents. Heat converted these soluble precursors to insoluble polyimides having good high‐temperature physical properties.
Copolymerization of acrylonitrile. II. Physical and mechanical properties of copolymers with styrene derivatives containing nitrile groups in the side chain
Authors: Ronel Samuel H. , Kohn David H. 
Published: April 2003

AbstractCopolymers of acrylonitrile with cinnamonitrile (I), ethyl benzylidenecyanoacetate (II), and benzylidenemalononitrile (III) were prepared in suspension up to high conversions. Films and molded specimens were made from the copolymers and their basic physical and mechanical properties, such as solubility, viscosity, glass transition temperature, and tensile and compressive strength were determined. Further, treatment by heat and ultraviolet light, the permeability of water vapors, and the behavior of films in a weathering tester were studied.
High‐temperature polymerization of ϵ‐caprolactam by using as catalyst the Li, Na, or K salts derived from MAlEt4 or MOAlEt2·AlEt3 and monomer
Authors: Konomi T. , Tani H. 
Published: April 2003

AbstractHigh‐temperature polymerization of ϵ‐caprolactam by using the salts derived from MAlEt4 (where M is Li, Na, and K) and monomer as catalyst was carried out. Polymerization occurs at 140–170°C, a temperature at which alkali metal caprolactamate has almost no catalytic activity for initiation. m‐Cresol‐insoluble polymer was obtained at temperatures lower than 231°C. Formation of a m‐cresol‐insoluble polymer depends on the polymerization temperature and time, and was observed under conditions where Al(Lac)3 has no catalytic activity. All the polymers obtained by NaAl(Lac)4–n(NHBu)n (n = 1 or 2) at 202°C were soluble in m‐cresol. These trends observed in the case of MAl(Lac)4 are considered to be due to initiation by Al(Lac)3, which is a component of the catalyst used.
Chain transfer in anionic polymerization. Determination of chain‐transfer constants by using carbon‐14‐labeled chain transfer agents
Authors: Gatzke Arnold L. 
Published: April 2003

AbstractA method is described in which 14C‐labeled chain‐transfer agents are employed to measure chain‐transfer constants in anionic polymerization as low as 10−6. Each chain‐transfer step incorporates one molecule of the chain‐transfer agent into the polymer so that measurement of the activity and conversion allows evaluation of the chain‐transfer constant. This method is independent of the initiator concentration and efficiency, making the technique especially useful when problems with the initiator are encountered. The experimental procedure is described in detail for the case of chain transfer to toluene in the n‐butyllithium‐initiated polymerization of styrene, where CRH was found to be 5 × 10−6. A mathematical treatment is given showing the relationship between the degree of polymerization (DPn) and chain transfer.
Synthesis and polymerization of 1‐ and 2‐cyano‐1,3‐butadienes
Authors: Wei Peter E. , Milliman George E. 
Published: April 2003

Abstract1‐Cyano‐1,3‐butadiene and 2‐cyano‐1,3‐butadiene were prepared and designated 1‐cyanoprene and 2‐cyanoprene, respectively. These compounds, and their intermediates, were characterized by their infrared and proton magnetic resonance spectra. Their polymerizations with lithium or aluminum alkyl catalysts are described. The synthesis of these monomers involves a thermal cracking process (400–500°C). The yield of monomer by this process depends on the positions of the cyano and acetoxy groups in the butene intermediate; if the cyano and the acetoxy groups are attached to the same allylic carbon, a low monomer yield is obtained. The polymers of 1‐cyanoprene are the results of 1,4‐enchainment (cis and trans) and are amorphous; the polymers of 2‐cyanoprene may involve 1,4‐enchainment but are partially crystalline. Both of these polymers are thermoplastic.