bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the effect of stabilizer on the degradation of poly(vinyl chloride) by pyrolysis–gas chromatography
Authors: Suzuki Mikio , Tsuge Shin , Takeuchi Tsugio 
Published: April 2003

AbstractThe effect of stabilizer on the thermal degradation of poly(vinyl chloride) was studied by means of pyrolysis–gas chromatography. The stabilizers used in this study were dibutyltin dilaurate, dibutyltin bis(n‐dodecyl mercaptide), barium stearate, and zinc stearate. PVC containing these stabilizers was degraded in a stream of nitrogen at temperatures ranging from 350 to 570°C. It was found that observed drastic reduction of benzene yield from the PVC containing zinc stearate had a close correlation with the formation of crosslinking structures.
Synthesis and polymerization of heteroaromatic vinyl monomers
Authors: Iwakura Yoshio , Toda Fujio , Suzuki Hideaki , Kusakawa Norihisa , Yagi Kohji 
Published: April 2003

AbstractMethods of preparing new monomers, 2‐vinyl and 2‐isopropenyloxazoles and 2‐isopropenyl‐1,3,4‐oxadiazoles are described. New methods were developed to synthesize monomers containing an isoxazole or a thiazole ring. Radical homopolymerization and copolymerization with styrene of these monomers were carried out by using AIBN as an initiator. Monomer reactivity ratios r1, r2 and Alfrey‐Price Q–e values were determined by the Fineman‐Ross and the Mayo‐Lewis methods. The localization energy of the β‐carbon was calculated by a HITAC‐5020 computer, and the monomer reactivity is discussed in terms of Lβ.
Stereoregularity of poly(isopropyl acrylate) and its racemization during hydrolysis
Authors: Matsuzaki Kei , Okada Munehisa , Hosonuma Kunihiko 
Published: April 2003

AbstractThe diad tacticity of poly(isopropyl acrylate) was measured from the β‐proton absorptions of poly(isopropyl acrylate‐α,β‐d2) obtained with a 100 MHz NMR spectrometer, and temperature dependence of the tacticity of the polymers obtained by radical polymerization was determined. Enthalpy and entropy differences between isotactic and syndiotactic addition for poly(isopropyl acrylate) were calculated to give the following values: Δ(ΔS) = 0.7 eu; Δ(ΔH) = 0.51 kcal/mole. In the hydrolysis of poly(isopropyl acrylate‐α,β‐d2), it was found that the rate of hydrolysis of poly(isopropyl acrylate) was dependent on the molecular weight rather than on the tacticity. As for the rate of racemization during hydrolysis, the rate for syndiotactic polymer was much faster than that for the isotactic polymer. The exchange reaction of deuterium at α‐position with hydrogen occurred in all the polymers during hydrolysis reaction.
Catalysis of novolacs by p‐phenolsulfonic acid
Authors: Wagner E. R. , Greff R. J. 
Published: April 2003

AbstractThe reaction rate of phenol and aqueous formaldehyde in the presence of p‐phenolsulfonic acid has been studied. The increase in pH during the reaction, which decreases the reaction rate, can be correlated with the disappearance of polyoxymethylene (formaldehyde), but not as previously supposed solely with the dilution effect of the water formed from the reaction. Gel‐permeation chromatography was used to monitor the consumption of phenol and the growth of polymeric species. It has been demonstrated that the formation of a second liquid phase during the novolac process is independent of the amount of catalyst. The liquid two‐phase system and its relation to the reaction rate have been examined. The final molecular weight distribution of novolacs is dependent not only on the initial pH of the system, but also on the pH at the onset of devolatilization.
New thermally stable polymer with a graphite‐type structure
Authors: Hurley S. A. , Dutt Prabir K. , Marvel C. S. 
Published: April 2003

AbstractA new thermally stable polymer with a structure resembling that of graphite has been synthesized by the condensation of 1,4,5,8‐tetraaminoanthraquinone and 1,3,6,8‐tetraketo‐1,2,3,6,7,8‐hexahydropyrene (naphthalene‐1,8,4,5‐diindandione). Prepolymers, with an open structure, were soluble to some extent in concentrated sulfuric acid but were more completely solubilized by methanesulfonic acid. The final polymer with a closed‐ring structure, which was obtained by heating the prepolymer having an inherent viscosity of 0.4, was completely insoluble in these acids. Elemental analysis indicated that a high degree of cyclization was achieved, and the final polymer showed good thermal stability. Prepolymers with inherent viscosities in the range 0.11–1.58 have been obtained but, usually, a high viscosity was accompanied by a low acid solubility. Prepolymers with an inherent viscosity of 0.4, which were very soluble (>90%) in strong acids, were solubilized to a high degree by reduction with sodium dithionite in alkaline, aqueous dimethylacetamide. The highest molecular weight prepolymer (inherent viscosity of 1.30–1.58) was solubilized to a greater extent in this base mixture than in methanesulfonic acid. However, it was not completely soluble, under the conditions employed. The propolymers of higher molecular weight showed some fiber‐ and film‐forming properties.
Temperature and concentration effects on polar‐modified alkyllithium polymerizations and copolymerizations
Authors: Antkowiak T. A. , Oberster A. E. , Halasa A. F. , Tate D. P. 
Published: April 2003

AbstractAddition of polar modifiers to alkyllithium‐initiated homopolymerizations of butadiene causes substantial changes in the microstructure of the polymers produced. These changes are shown to depend not only on the concentration of modifier, but also on the polymerization temperature. The combined effects of modifier concentration and reaction temperature have been considered, and a method is presented for quickly determining the proper conditions for preparation of a polybutadiene of any 1,2‐microstructure within a range of 10–80%. It is also shown that in anionic polar‐modified copolymerizations of butadiene–styrene, the reaction temperature is again critical. Within a certain concentration range of modifier, the temperature will influence the rate of styrene incorporation or the randomness of styrene units in the resulting copolymers.
Syntheses of vinyl polymers containing a large π‐electron cloud in the side chain
Authors: Kamogawa Hiroyoshi 
Published: April 2003

AbstractSeveral novel vinyl polymers containing five fused benzene rings in side chains were synthesized either by polymerization of the appropriate vinyl monomers or by chemical modification of the appropriate polymer. Thus, 3‐(α‐acryloyloxy)ethylperylene was prepared from perylene by Friedel‐Crafts acylation with acetyl chloride and subsequent hydrogenation, followed by the reaction of the resulting alcohol with acryloyl chloride. 3‐Acrylamido‐ or methacrylaminoperylene was prepared by the nitration of perylene, reduction of the resulting 3‐nitroperylene, and the reaction with acryloyl or methacryloyl chloride. p‐Vinylbenzal‐3‐acetylperylene was prepared by the condensation and dehydration reaction between p‐vinylbenzaldehyde and 3‐acetylperylene under alkaline medium, and, in the same manner, p‐vinylbenzal‐3‐aminoperylene was prepared from p‐vinyl benzaldehyde and 3‐aminoperylene. All these monomers were polymerized with α,α′‐azobisisobutyronitrile as catalyst in solution to afford the corresponding vinyl polymers. A vinyl polymer containing perylene‐3‐acetyl side chain was also prepared by the acetalization of poly(vinyl alcohol) with 3‐formylperylene.
γ‐ and ultraviolet‐radiation‐induced solid‐state polymerization of maleimide in a few binary systems
Authors: Hayakawa Kiyoshi , Yamakita Hiromi , Kawase Kaoru 
Published: April 2003

AbstractThe solid‐state polymerization of maleimide by γ‐ and ultraviolet irradiation was carried out in binary systems with succinimide, maleic anhydride, and acenaphthylene. Polymaleimide obtained from the solid‐state polymerization of maleimide by γ‐rays was amorphous, while that obtained from the solid‐state polymerization by ultraviolet rays was highly crystalline. In the maleimide–succinimide system the rate of polymerization reached a maximum nearly at the eutectic composition when the polymerization was carried out by γ‐irradiation. With ultraviolet irradiation the rate of polymerization became higher with increasing content of succinimide in the feed. In the maleimide–maleic anhydride system a copolymer of both constituents was formed by γ‐irradiation, but almost no homopolymer was produced. On the other hand, two kinds of polymers, a crystalline copolymer and an amorphous one, were produced by ultraviolet irradiation. The results were compared with those obtained from the copolymerization in solution. In the maleimide‐acenaphthylene system the main products with ultraviolet irradiation was the dimer of acenaphthylene.
Benzheterocycle–imide and amide–imide fibers derived from diacid chlorides containing preformed imide groups
Authors: Preston J. , Dewinter W. , Black W. B. 
Published: April 2003

AbstractFibers of benzoxazole–imide ordered copolymers were prepared by cyclodehydrating the amide–phenol units of precursor polyamide–o‐hydroxyimide fibers at 375°C in nitrogen. The precursor polyamide–o‐hydroxyimides were obtained by the reaction of 3,3′‐dihydroxybenzidine with diacid chlorides containing preformed imide rings. The benzoxazole–imide fibers are very thermally stable, especially with respect to retention of tensile properties after heat aging in air. For example, the benzoxazole–imide fibers after heating aging in air for 35 days retained 75% or more of their original tenacities and 50% or more of their original elongations to break. The original fibers did not have high tenacities, probably because of the rather extreme thermal treatment required to cyclodehydrate the amide–phenol units of the precursor fiber. The ultraviolet light stability of one benzoxazole–imide fiber was outstanding for a fiber of the polyheterocycle type: there was no loss in strength or elongation after 140 hr of exposure in a Fade‐Ometer. Fibers of ordered amide–imide polymers based on the same imide‐containing diacid chlorides used for the benzoxazole–imide polymers were also prepared. They were substantially less thermally stable than their benzoxazole–imide fiber counterparts, as expected.
Applications of ESCA to polymer chemistry: Studies of some nitroso rubbers
Authors: Clark D. T. , Kilcast D. , Feast W. J. , Musgrave W. K. R. 
Published: April 2003

AbstractMolecular core binding energies of the polymers formed by copolymerization of CF3NO with CF2CF2, CF2CFCl, and CF2CFH, respectively, have been studied by means of ESCA. The results are interpreted in terms of CNDO/2 SCF MO calculations on some model systems. Some evidence for structural irregularity is found for the copolymers with CF2CFCl and with CF2CFH. The reaction mechanism for the polymerization is also discussed in terms of the experimental results and INDO SCF MO calculations.
Photochemistry of poly(vinyl cinnamylideneacetate) and related compounds
Authors: Tanaka Hideaki , Tsuda Minoru , Nakanishi Hiroshi 
Published: April 2003

AbstractThe photochemistry of the cinnamylideneacetyl group was investigated with respect to a photosensitive polymer, poly(vinyl cinnamylideneacetate). The photochemical reaction of 1,4‐butanediol dicinnamylideneacetate was intramolecular cyclobutane formation. The photosensitive polymer underwent dimerization of the cinnamylideneacetyl moiety to form a cyclobutane ring. The reactivity of the double bond adjacent to the carbonyl group was larger than that of the double bond adjacent to the phenyl group in the chromophore. The quantum yield of the reaction was larger in the solid state than in solution: ϕ > 1.2 in crystalline state, ϕ = 0.5 in polymer film, ϕ = 0.1 in solution. The reaction was sensitized by triplet sensitizers (ET > 42 kcal/mole). The thermal reaction of the polymer was completely different from the photochemical reaction. A radical initiator was very ineffective for reaction of the polymer.
Perfluoroalkylene‐linked aromatic polyimides. I. Synthesis, structure, and some general physical characteristics
Authors: Critchley J. P. , Grattan Patsy A. , White Mary A. , Pippett J. S. 
Published: April 2003

AbstractThis paper describes the preparation of a series of novel perfluoroalkylene‐ and ether‐linked aromatic polyimides. Depending on the nature of the precursor diamine, the polyimides were prepared by either melt or solution techniques, the latter via the corresponding poly(amic acids). The polymers were characterized by a variety of methods, and their structure is discussed.
Study of (π‐C5H5)2Ti(CH3)Cl and (π‐C5H5)2Ti(C6H5)Cl in soluble Ziegler catalysts
Authors: Waters J. A. , Mortimer George A. 
Published: April 2003

AbstractSoluble ethylene polymerization catalysts derived from (π‐C5H5)2Ti(R)Cl and R ′AlCl2, where R = methyl or phenyl and R ′ = methyl or ethyl, were studied both by polymerization kinetics at 0°C and by diagnostic experiments. It was found that the first insertion of ethylene into the TiR bond is difficult when R = methyl or phenyl, and for this reason these catalysts show a different overall behavior than when R = ethyl or higher alkyl.
Cyclization of synthetic cis‐1,4‐polyisoprene
Authors: Agnihotri Ram K. , Falcon D. , Fredericks E. C. 
Published: April 2003

AbstractCyclization of synthetic cis‐1,4‐polyisoprene was carried out by using TiCl4 and p‐toluenesulfonic acid catalyst. The average cyclicity and structure of the polymers cyclized to a different degree was studied by infrared and high‐temperature NMR spectroscopy. The methods of synthesizing an average mono‐, bi‐, tri‐, or polycyclic polymer that could be distinguished by high‐temperature NMR spectroscopy and followed by gel‐permeation chromatography are discussed.
Adsorption of gas on ion exchangers. III. The pore structure of m‐aminophenol–formaldehyde condensation resins
Authors: Hashida Isao , Nishimura Masato 
Published: April 2003

Abstractm‐Aminophenol was condensed with formaldehyde in an acid medium in the presence of a water‐soluble inorganic salt (NaCl, CaCl2 etc) and/or poly(ethylene glycol). The pore structure characteristics of the condensation products were investigated by measurements of average pore size, pore size distribution of channels, total pore volume, surface area, and electron microscopic observation. The type and concentration of inorganic salts appeared to be a significant variable for the resulting pore structure, while poly(ethylene glycol) had a little effect. The nongel interstices of products were channels between many agglomerates of minute spherical gel particles with narrow pore size distribution. The diameters of these spherical gel particles were 3–10 × 10−1µ from the scanning electron microscopic observation. Apparent dissociation constants of functional groups of resin, pKa and pKb, estimated by using the Henderson‐Hasselbach equation, were 10.94 and 10.99, respectively. The resin had an ion‐exchange capacity of 1.0 meq/g for base and 4.8 meq/g for acid.
Polymerization of vinyl stearate multilayers
Authors: Cemel A. , Fort Tomlinson , Lando J. B. 
Published: April 2003

AbstractA study was made of the solid‐state polymerization of built‐up monomolecular layers of vinyl stearate. Polymerization was initiated by exposing the samples to 60Co γ‐radiation. The reactions were followed by multiple internal reflection infrared spectroscopy. The structure of the multilayer monomer and polymer was studied by x‐ray diffraction. Surface properties of the multilayers were studied by contact‐angle measurements. Results showed that, under the proper conditions, monomer multilayers of vinyl stearate could be polymerized to virtually 100% completion. Reaction was favored by higher irradiation temperatures, larger doses of radiation, and by higher reaction temperatures. The x‐ray diffraction photographs indicated that both the monomer and polymer multilayers possessed some single crystal character. Contact‐angle measurements indicated that the molecules in both the monomer and polymer multilayers were closely packed.
Polymeric supports in peptide synthesis: An alternate preparation of crosslinked 4‐hydroxy‐3‐nitropolystyrene
Authors: Williams R. E. 
Published: April 2003

AbstractAn alternate preparation of the solid‐phase synthetic resin, crosslinked 4‐hydroxy‐3‐nitropolystyrene, is described. The reaction sequence, starting from a commercially available material, includes demethylation of crosslinked 4‐methoxypolystyrene by a mild procedure and nitration of the resulting 4‐hydroxypolystyrene. The final product is identical in all respects with that which has been previously prepared by a much longer route. A racemization test which involves tripeptide formation and separation of the diasteriomeric peptides produced by ion‐exchange chromatography indicates very large amounts of racemization may be associated with the use of the resin if care is not exercised in the choice of amino‐acid‐blocking groups.
Molecular weight distributions in radiation‐induced polymerization. VI. γ‐ray‐induced polymerization of “dry” styrene in the solid state
Authors: Westlake John F. , Huang Robert Y. 
Published: April 2003

AbstractThe γ‐ray‐initiated polymerization of styrene in the solid state has been studied over the temperature range −35°C to −55°C for samples exhaustively purified and dried to remove residual water (“dry” samples). Comparison with kinetic results previously reported for dry samples in the liquid state indicates a sharp decrease in the rate of polymerization resulting from the liquid to solid state transition. The molecular weight distributions for in‐source polymerization at −35°C and −40°C are bimodal in nature, and the appearance of a third peak is noticeable at −47°C and −55°C. In the case of postpolymerization at −35°C the molecular weight distribution is bimodal as in the case of in‐source samples. In the former case, however, the high molecular weight peak is predominant whereas the low molecular weight peak predominates in the latter. These results have been tentatively attributed to the postulated coexistence of two distinct propagating species which are radical and cationic in nature.
Dilute solution properties of sodium amylopectin xanthate
Authors: Manna P. K. , Choudhury P. K. 
Published: April 2003

AbstractSodium amylopectin xanthate, prepared by xanthation of potato amylopectin in alkaline medium, was fractionated and the fractions in 1M NaOH were characterized by viscometry and light scattering. The expansion factor α was determined from the expression due to Orofino and Flory. The value of a of the Mark‐Houwink relation, [η] = KMa, was also determined. Its weight‐average molecular weight, end‐to‐end distance, branching, and other parameters in alkali solution were also evaluated. From the data, it was concluded that the sodium amylopectin xanthate molecule had a polydisperse random‐coil chain configuration in 1M NaOH and had no tendency to aggregate in this medium.
Radiation‐induced polymerization of tetraoxane in the solid state. II. Molecular weight distribution
Authors: Nakase Yoshiaki , Yoshida Masaru , Ito Akihiko , Hayashi Koichiro 
Published: April 2003

AbstractIn order to investigate the mechanism of the radiation‐induced postpolymerization of tetraoxane in the solid state, the polymer was fractionated, and the fractions were characterized by reduced viscosity. The molecular weight of polymer formed in vacuo decreased drastically after the introduction of oxygen under conditions such that the polymer yield increased. The decrease in the molecular weight in the postpolymerization of tetraoxane is attributed to degradation of the polymer in the presence of oxygen. It is suggested that at least peroxides formed by preirradiation contribute to both the increase in polymer yield and the decrease in molecular weight of the polymer.
Kinetics of polymerization initiated by peroxides containing heterocyclic groups. I. Kinetics of bulk polymerization of styrene and vinyl acetate initiated by difuroyl peroxide
Authors: Molnar S. 
Published: April 2003

AbstractThe rate and degree of bulk polymerization of styrene and vinyl acetate initiated by difuroyl peroxide and, for comparison, by dilauroyl and dibenzoyl peroxides were measured at several temperatures as a function of the initiator concentration. Also the rates of initiation were determined by the inhibition method with Banfield's radicals. The rate of polymerization initiated by difuroyl peroxide appears to be lower than could be expected from the rate of initiation determined by the inhibition method and from the decomposition of difuroyl peroxide. In the case of polymerization of vinyl acetate there are significant deviations from the proportionality between Rp and the square root of the initiator concentration, which follows from the conventional kinetic scheme. The degrees of polymerization are also low, and the plots of Pn−1 versus Rp are not linear. These deviations can be accounted for by postulating a retardation effect of the furan cycle and chain transfer to difuroyl peroxide.
Asymmetric polymers. XXV. Synthesis of some optically active c‐substituted hexahydro‐2H‐azepin‐2‐ones
Authors: Overberger C. G. , Kozlowski John H. , Radlmann Edward 
Published: April 2003

AbstractA series of optically active hexahydro‐2H‐azepin‐2‐ones substituted at the 5 position were prepared from (S)( − ) and (R)(+)‐hexahydro‐5‐carboxy‐2H‐azepin‐2‐one obtained via resolution of the racemic acid with brucine. Racemic hexahydro‐5‐carboxy‐2H‐azepin‐2‐one was synthesized from 4‐oxocyclohexanecarboxylic acid. Interest in many substituted hexahydro‐2H‐azepin‐2‐ones (ϵ‐caprolactams, 2‐oxohexamethyleneimines) stems in part from their ability to form polymers of the nylon 6 type whose properties may be systematically modified through regulation of the nature and position of the lactam substituent. Further structural control is possible through the use of optically pure monomers. An asymmetric seven‐membered lactam with a polar substituent might lead to a stereoregular polyamide where interaction between the side chain and the polymer backbone could influence the conformational properties of the polymer. A side chain such as the hydroxymethyl moiety would be expected to favor hydrogen bonding. This question is discussed in more detail in the paper which follows on the optical properties of the polymer.
Thermal degradation of a polyphenylquinoxaline in air and vacuum
Authors: Augl Joseph M. 
Published: April 2003

AbstractA series of poly[2,2′‐(1,4‐phenylene)‐6,6′‐bis(3‐phenylquinoxalines)] were prepared. These polymers had all the same repeating unit but differed in molecular weight and polymer chain endings. The thermal degradation characteristics in air and vacuum were determined by isothermal weight loss measurements. The temperature coefficients of thermal degradation (apparent activation energies) were also determined. Whereas the apparent activation energies for degradation in air showed a considerable dependency on the type of polymer chain endings, no such effect was observed upon pyrolysis in vacuo. A possible chain‐end unzipping mechanism of degradation in air is postulated to explain these results.