bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of low‐molecular‐weight polyethylene treated with gas plasma
Authors: Ashida Michio , Ikada Eiji , Ueda Yasukiyo , Aizawa Hideki 
Published: April 2003

AbstractPolyethylene films were evaporated in gas plasmas of Ar, N2, O2, and H2O. The deposits were analyzed by infrared (IR) spectroscopy to determine the concentration of characteristic functional groups. The deposit prepared in Ar‐atmosphere had a rather high concentration of methyl group and many double bonds were produced in the film. The deposits prepared in Ar‐ and N2‐plasmas produced similar spectra, which showed twice the concentration of methyl group than the deposit in Ar‐atmosphere and also contained a few carbonyl and hydroxyl groups. The film treated in O2‐plasma contained the largest amount of carbonyl group and the lowest number of double bonds among the plasma‐treated deposits. Dielectric loss curves against temperature for the deposits treated in these plasmas showed a broad peak near 20°C. For O2‐plasma‐treated film the loss tangent curves showed a sharp maximum. The activation energy for the relaxation of Ar‐, O2‐, and H2O‐plasma‐treated films had the same value of 50.6 kcal/mol. The observed relaxation in the films prepared in gas plasmas was considered due to the β process and was attributed to the motion of oxidized branched polyethylene.
Interaction of poly(vinyl acetate) radical with iron (III) complexes
Authors: Begum S. S. , Dass N. N. 
Published: April 2003

AbstractThe polymerization of vinyl acetate in N,N‐dimethylformamide (DMF) at 60°C initiated by AIBN in the presence of [Fe(DMF)6](ClO4)3 and Fe(N3)3 had been studied. Fe(N3)3 was produced in situ by mixing solid sodium azide (NaN3) and hexakis(N,N‐dimethylformamide) iron (III) perchlorate, [Fe(DMF)6](ClO4)3, in the ratio of 3:1. The velocity constant kx for the interaction of poly(vinyl acetate) radical with [Fe(DMF)6]3+ was found to be 1.44 × 103L mol−1 s−1 and that for the interaction of poly(vinyl acetate) radical with Fe(N3)3 to be 3.44 × 105 L mol−1 s−1 at 60°C.
Chemical release control—Schiff bases of perfume aldehydes and aminostyrenes
Authors: Kamogawa Hiroyoshi , Mukai Hiroshi , Nakajima Yoichi , Nanasawa Masato 
Published: April 2003

AbstractSchiff bases of p‐ and m‐aminostyrenes with perfume aldehydes such as citral, cinnamaldehyde, piperonal, vanillin, and ethyl vanillin were synthesized in ethanol in more than 50% yield. Water‐soluble copolymers of these Schiff bases with N‐vinyl‐2‐pyrrolidone or with N,N‐dimethylacrylamide were obtained. The hydrolytic behavior of Schiff base monomers and copolymers to liberate perfume aldehydes was structure dependent, thereby affording chemical release control.
Monte Carlo study of star‐branched polymers on the tetrahedral lattice. I. Conformation of the macromolecule
Authors: Kolinski Andrzej , Sikorski Andrzej 
Published: April 2003

AbstractThe star‐branched polymers on the tetrahedral lattice are studied by means of the Monte Carlo method. The influence of solvent quality on the dimensions of the coil is described for both linear and branched polymer systems of different functionality. It has been observed that the ratios of gyration radii 〈S2〉b/〈S2〉l are greater than those predicted theoretically for the random‐flight model. The fourth reduced moment of S2 distribution and the mean‐square separation of the branch ends from the center of gravity have been also computed. The changes in segment arrangement in the coil with increasing number of branches have been observed.
Polymerization of cyclohexene oxide with aluminum complex/silanol catalysts. V. A catalytic activity dependence on the aluminum chelate structure
Authors: Hayase S. , Onishi Y. , Yoshikiyo K. , Suzuki S. , Wada M. 
Published: April 2003

AbstractThe catalytic activity of an aluminum complex/silanol system was found to vary with the aluminum ligand as follows: β‐diketonate < β‐ketoester anion < ortho‐carbonylphenolate. Aluminum complexes with electron donating groups conjugated with a carbonyl group had higher catalytic activity. The catalyst activity correlated with the strength of interaction between the aluminum complex and the silanol; there were two such interaction mechanisms. Cyclohexene oxide was polymerized cationically by the activated proton of SiOH. The activated proton is considered to be similar to Brönsted acid on silica‐alumina catalyst; therefore, the catalyst would be a model of the silica‐alumina catalyst.
Poly(β‐pinenes) carrying one, two, and three functional end groups. II. Syntheses and characterization
Authors: Kennedy J. P. , Liao Tung‐Ping , Guhaniyogi Suhas , Chang Victor S. C. 
Published: April 2003

AbstractConditions for the convenient synthesis of linear poly(β‐pinenes) that carry one or two tert‐chloro end groups (∼Clt) and three‐arm star poly(β‐pinenes) that carry three termini have been worked out. Specifically, the polymer with one ∼Clt end group was prepared by the H2O/BCl3 system, whereas those with two and three ∼Clt termini were prepared by the use of p‐dicumyl chloride and sym‐tricumyl chloride/BCl3 inifer combinations. The ∼Clt‐terminated polymers were dehydro‐chlorinated to yield the corresponding olefins. The molecular weights of the products were low enough to permit infrared (IR) and quantitative 1H‐NMR investigations. Poly(β‐pinene‐b‐tetrahydrofuran) diblock copolymers have been synthesized by inducing the polymerization of tetrahydrofuran (THF) by the PβClt/AgCF3SO3 initiating system.
Properties of poly(p‐phenylene)s and the perdeuterated analog
Authors: Hsing Chih‐Fen , Khoury Issam , Bezoari Massimo D. , Kovacic Peter 
Published: April 2003

AbstractESR data for poly(p‐phenylene) (PPP) prepared from benzene and catalyst‐oxidant systems were compared with data for PPP obtained by a variety of other methods. The results were similar, except for the Yamamoto preparation, and comparable to the spin densities for heterocyclic polymers of thiophene, pyrrole, and selenophene. Deuterated PPP from C6D6 showed significant differences in properties, in comparison to ordinary PPP, in relation to molecular weight, color, solubility, and spins/g in electron spin resonance (ESR). The implications are discussed with regard to the mechanism of benzene polymerization by AlCl3‐CuCl2.
Condensation polymerization of oligomeric polydimethylsiloxanols in aqueous emulsion
Authors: Saam John C. , Huebner David J. 
Published: April 2003

AbstractPolydimethylsiloxane oligomers with silanol ends condense in aqueous dispersion under mild conditions to form high polymers in the presence of sulfonic acid surfactants. The process follows a second‐order rate law in silanol if reversibility is taken into account. The second‐order rate constant is proportional to the area at the oil–water interface and is a complex function of surfactant concentration. The principal driving force is the heat of condensation of the water produced in the polymerization. A mechanism paralleling surface catalysis is offered in which a termolecular complex that consists of two surfactant molecules and one silanol end group reacts bimolecularly at the oil–water interface.
Phase‐transfer reactions catalyzed by phosphonium salts attached to polystyrene resins by spacer chains
Authors: Tomoi Masao , Ogawa Eiji , Hosokama Yasunori , Kakiuchi Hiroshi 
Published: April 2003

AbstractThe rate of reaction of 1‐halooctanes with aqueous sodium cyanide catalyzed by phosphonium salts attached to insoluble polystyrene resins by tetramethylene or heptamethylene spacers was studied as a function of catalyst particle size, degree of polymer crosslinking, percentage of ring substitution, and temperature. Rates of reaction of 1‐bromooctane with 17–38% ring‐substituted catalysts increased as spacer‐chain length increased. Rates of reaction of 1‐bromooctane decreased, whether the percentage of ring substitution increased or decreased from 17–19%. Rates of reaction of 1‐chlorooctane increased with increasing spacer‐chain length and decreasing percentage of ring substitution. Apparent activation energy for the reaction of 1‐bromooctane with 9% ring‐substituted, spacer‐modified catalysts was 9–10 kcal/mol and 13 kcal/mol with 17–19% ring‐substituted catalysts. The hydrophilicity of catalysts decreased with increasing spacer‐chain length and decreasing percentage of ring substitution. The mechanisms of reaction were discussed in terms of intrinsic reactivity and intraparticle diffusion limitations on the reaction rates.
Syntheses and characterization of N‐grafted poly(p‐phenylene terephthalamide)
Authors: Takayanagi Motowo , Katayose Teruo 
Published: April 2003

AbstractN‐grafted poly(p‐phenylene terephthalamide)s (PPTA) were synthesized from PPTA and acrylonitrile or propylene oxide via metalation in a solution of the polymer in a sodium methylsulfinylcarbanion–dimethyl sulfoxide solvent at low temperatures. The introduction of these branches into the amide groups of PPTA increased solubility but decreased thermal stability. The effects of the branches on thermal properties and solubility are discussed. The structure of the graft copolymers is described on the basis of wide‐angle x‐ray diffraction, infrared spectra, and solubility.
Preparation of polysiloxanes from silicic acid. III. Preparation and properties of polysilicic acid butyl esters
Authors: Abe Yoshimoto , Misono Takahisa 
Published: April 2003

AbstractPolysilicic acid butyl esters were prepared from 1‐butanol and silicic acid extracted from sodium metasilicate solution and water glass with tetrahydrofuran and hydrochloric acid. The properties of the esters were dependent on the degree of esterification (DE). The esters with a DE of less than ca. 60% could be isolated by precipitation with hexane and were highly liable to self‐condensation, whereas those with more than 60% DE were soluble in solvents and could not be precipitated easily. They underwent further condensation to form highly polymerized esters. Subsequent silylation allowed the isolation and characterization of these esters. The solvent‐soluble silylated esters had moderate thermal stability with decomposition points between 210 and 260°C and number‐average molecular weights of 10,000–30,000. From the evaluation of units structures of silylate it was suggested that polymer backbone was a pseudoladder structure.
Rigid‐ladder polymers: Polymers containing anthraquinone recurring units
Authors: Lee Byung H. , Marvel C. S. 
Published: April 2003

AbstractIn an attempt to synthesize some processable ladder or partial ladder polymers containing anthraquinone recurring units, leucoquinalizarin was treated with 3,3′‐diaminobenzidine. This polymer, which was a black powdery material, was slightly soluble in concentrated sulfuric acid and dimethylsulfoxide. Also, 1,5‐diamino‐2,6‐dimercaptoanthraquinone was condensed with 2,5‐dichloro‐p‐benzoquinone in pyridine to give a black powdery polymer. This was only partially soluble in concentrated sulfuric acid, but could be solubilized in alkali by reduction with sodium dithionite.
Carbon‐13 NMR microstructural characterization of dichlorocarbene adducts of polybutadiene
Authors: Komoroski Richard A. , Horne Samuel E. , Carman Charles J. 
Published: April 2003

Abstract13C‐NMR has been used to examine a number of dichlorocarbene adducts of cis‐ and trans‐polybutadiene prepared in a two‐phase system. Dichlorocarbene was generated by reaction of aqueous or solid NaOH or KOH with CHCl3 in the presence of a phase transfer catalyst. Monomer compositions, comonomer sequence lengths, and stereochemical information were obtained for the resulting polymers. The polymers examined here were stereochemically pure and were treated as simple copolymers. Samples prepared using aqueous NaOH can be described as essentially random copolymers over the entire range of monomer composition. Samples prepared using solid alkali‐metal hydroxides contain a higher fraction of blocked units than a polymer of comparable composition prepared using aqueous NaOH. This blockiness can coincide with the presence of two glass transition temperatures and a two‐phase morphology as seen by transmission electron microscopy. Fractionation of a substantially blocked sample yielded a chlorine‐poor fraction which was a random copolymer and a chlorine‐rich fraction which was more blocked than the original unfractionated material.
Diaryliodonium salts as thermal initiators of cationic polymerization
Authors: Crivello J. V. , Lockhart T. P. , Lee J. L. 
Published: April 2003

AbstractDiaryliodonium salts (I) undergo efficient thermal decomposition in the presence of copper (II) compounds. Such systems can be employed as a novel class of latent thermal initiators for cationic polymerization. An investigation of the mechanism of the reaction demonstrated that the copper (II) compound is first reduced to the corresponding copper (I) compound, which subsequently reduces the diaryliodonium salt. The cationic polymerization of some typical monomers using these new initiators was carried out to demonstrate the scope of their utility.
Synthesis and characterization of polymerizable bisphthalonitrile monomers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractThe reactions of 4‐aminophthalonitrile (APN) with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BPTDA), and with 1,2,3,4‐benzenetetracarboxylic dianhydride (PMDA) have been studied to optimize the conditions for the synthesis of monomeric thermosetting bisphthalonitrile compound. Suitable procedures for the synthesis of the two monomers are presented. Elemental analyses, IR spectra, dynamic thermogravimetric analyses, differential scanning calorimetry, 1H‐NMR, and mass spectral studies have been used to characterize these compounds. Preliminary observations show that these materials can be polymerized to give high‐temperature‐resistant materials.
Investigation of the structure of polymeric microemulsions by proton magnetic resonance
Authors: Ballet François , Candau Françoise 
Published: April 2003

AbstractThe structure of polymeric microemulsions, viz. toluene/water/PS‐PEO graft copolymer/2‐propanol, has been studied by 1H‐NMR spectroscopy. Results show that at low water contents, the copolymer adopts a rather diffuse micellar structure in which the rotational mobility of the ethylene oxide units is little affected by the ternary solvent mixture. Above a critical water concentration (ca. 4%), a restriction in mobility of the ethylene oxide chains is observed which has been related to the formation of an inverse micellar structure with water solubilized within the particles. The study of the chemical shifts and linewidths of water protons indicates that initially most of the water is hydrogen bonded to the hydrophilic part of the copolymer, then is present in its free form in water aggregates. These results confirm previous data obtained by dialysis equilibrium experiments.
The aging of living α‐methylstyryl oligomers. II. The mechanism of aging
Authors: Comyn J. , Glasse M. D. 
Published: April 2003

AbstractThe living anions of oligomeric α‐methalystyrene in THF transform to a new anion in the presence of excess monomer and UV light. Kinetic results have demonstrated that one step in this process is the second‐order disappearance of monomer to form a dimeric intermediate. We have attempted to prepare this intermediate. Contrary to other reports, no hydrogen was liberated on terminating the reactions mixture with water, and an oily liquid which was identified as 1‐methyl‐1,3‐diphenyl‐cyclopentane was isolated. However, this is not the intermediate; the true intermediate is 2,5‐diphenylhex‐1‐ene and under the conditions of the reaction the former compound is formed from this by a cyclization reaction.
High‐temperature resins based on aromatic amine‐terminated bisaspartimides
Authors: Kumar Devendra , Fohlen George M. , Parker John A. 
Published: April 2003

AbstractVarious 4,4′‐bis{N2‐[4‐(4‐aminophenoxy)phenyl]aspartimido}diphenylmethane (APADM)‐type precursors were synthesized by Michael‐type reaction of an aromatic bismaleimide (1mol) with an aromatic diamine (2 mol) in an aprotic solvent. The structures of these materials were characterized by using Fourier‐transform infrared (FT‐IR), 1H nuclear magnetic resonance (NMR) and 13C‐NMR; their curing behaviors and thermal stabilities were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermal polymerization of APADM by heating it above its melting temperature produced a tough polymer. From these preimidized precursors, graphite‐fiber laminates were prepared and their mechanical properties evaluated. To elucidate the thermal curing mechanism and the structure of the polymer, a model compound, N‐[4‐(4′‐aminobenzyl) phenyl] aspartimidobenzene was synthesized. The gas‐chromatographic mass spectra of these compounds has suggested a mechanism for their decomposition. The structure of the polymer also was studied by using FT‐IR and 1H‐NMR.
The examination of bromine‐containing fire retardants in unsaturated polyester resins by means of pyrolysis residue analysis
Authors: Ravey M. 
Published: April 2003

AbstractA method has been developed for following the bromine and weight losses of fire retarded UPE as a function of temperature. The results obtained by this method indicate that those bromine–containing fire retardants which exhibit a linear LOI–bromine concentration relation, the bromine concentration in the pyrolytically produced fuel remains more or less constant, while for those materials which deviate positively from the linear relation (that is they are more efficient), the bromine concentration in the fuel tends to peak at certain temperatures. When this effect is combined with variation in composition of the pyrolytic fuel, a situation can arise where a high bromine concentration coincides with a fuel particularly sensitive to flame quenching by bromine. Such a combined effect may be the reason why some brominated fire retardants are far more effective than others.
Radical polymerization of methyl methacrylate initiated by an enolizable ketone–carbon black system
Authors: Tsubokawa Norio , Shibata Naohiro , Sone Yasuo 
Published: April 2003

AbstractThe polymerization of methyl methacrylate (MMA) initiated by an enolizable ketone (R1COCH2COR2)‐carbon black system was investigated. Although enolizable ketone itself could not do so, the polymerization of MMA was initiated by enolizable ketone in the presence of carbon black. In addition, a chloranil‐enolizable ketone system was able to initiate the polymerization of MMA. It was found that the enol form of the ketone and quinonic oxygen groups on the carbon black surface played an important role in the initiation system; namely, it was considered that the polymerization was begun by the ketone radical (R1COCHCOR2) formed by a one‐electron transfer reaction from enolate ion to quinonic oxygen groups. The effect of solvent on the process was also studied. The rate of the polymerization increased, depending on the solvent used, in the following order: benzene < 1,4‐dioxane < dimethyl sulfoxide < N,N‐dimethylformamide < N‐methyl‐2‐pyrrolidone. Furthermore, it became apparent that during the polymerization poly(methyl methacrylate) was grafted onto the carbon black surface (grafting ratio was ca. 40% when benzene was used as solvent) and the carbon black obtained gave a stable colloidal dispersion in organic solvent.
Kinetcis and mechanism of HCN‐evolution from the oxidation of polyurethanes
Authors: Jellinek H. H. G. , Dunkle S. R. 
Published: April 2003

AbstractThe oxidative degradation of aliphatic, aromatic, and secondary polyurethanes was investigated over a range of temperatures of 440–1000°C as a function of time and oxygen concentration. The degradation was studied with special emphasis on HCN‐evolution; its rate constants and Arrhenius equations were determined. In some of the temperature ranges reactions were diffusion controlled. At relatively low temperatures the oxidative rate constant was a linear function of oxygen concentration, whereas at higher temperatures oxidation of the evolved HCN took place in passage through the hot zone of the furnace; in addition, at these higher temperatures thermal degradation of the polymers and thermal decomposition of HCN in the hot zone occurred simultaneously with oxidation to an appreciable extent. The kinetics and mechanism proposed and quantitatively evaluated account well for the experimental results.
Styrene and polystyrene microemulsions. I. Solubility in the W/O system
Authors: Gan Leong M. , Chew Chwee H. , Friberg Stig E. 
Published: April 2003

AbstractThe solubility of styrene, its oligomers, and different molecular weight polymers was determined in W/O microemulsions stabilized by sodium dodecyl sulfate and pentanol. The results showed a complex pattern due to the interactions with pentanol, surfactant, and associated structures.
Behavior of antioxidant in polyethylene
Authors: Matsumoto Shiro 
Published: April 2003

AbstractThe changes in the oxidative induction period of polyethylene and the concentration of antioxidant, 4,4′‐thio‐bis(3‐methyl‐6‐t‐butyl phenol), in polyethylene during thermal aging were investigated. The concentration decreased following a first‐order kinetics. The induction period depended only on the antioxidant concentration and was independent of the aging conditions. The Arrhenius plot of the rate constants of the concentration decrease was linear above and below the polyethylene melting range, and an activation energy was obtained. The main factor in the concentration decrease was the evaporation of the antioxidant from the surface, and the evaporation rate constant of the antioxidant dissolved in polyethylene was obtained.
A new solid‐phase polymerization—metal phthalocyanine sheet polymers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractThe thermal reactions of pure metal(11) 4,4′,4″,4′″‐phthalocyanine‐tetracarboxylic acids of copper, cobalt, and nickel at 350–400°C in vacuum have been studied using Fourier transform infrared spectrometry, gas chromatography, and mass spectrometry. Based on these observations, novel in situ reactions for the synthesis of heat‐resistant phthalocyanine “sheet” polymers are described. The poly(metal phthalocyanine) polymers of copper, cobalt, and nickel so synthesized have been characterized by elemental analysis, infrared spectroscopy, and dynamic thermogravimetric analysis. The most noteworthy property of these polymers is their extreme resistance to heat in an anaerobic atmosphere and their high char yields (89–93%) at 800°C in a nitrogen atmosphere.
Anionic polymerization of lactones initiated by alkali graphitides. I. Polymerization of ϵ‐caprolactone initiated by KC24
Authors: Rashkov Iliya B. , Gitsov Ivan , Panayotov Ivan M. , Pascault Jeanpierre 
Published: April 2003

AbstractThe influence of the reaction conditions (time, temperature, concentrations of the monomer, and the initiator) on the amount and composition of the oligomers and high molecular products formed during the heterogeneous anionic polymerization of ϵ‐caprolactone was investigated. The polymerization was initiated by KC24 in xylene or tetrahydrofuran. Conditions were found under which intra‐ and intermolecular transesterification was strongly suppressed, thus providing the opportunity for the formation of polyesters with viscometric molecular masses of more than 300,000 and good yields (80% and higher). The total quantity of products with a viscometric molecular mass below 2500 did not exceed 15%; that of the cyclic dimer was not in excess of 5%. Peculiar features of the KC24 initiated polymerization are the insignificant rise in the number of oligomers and the formation of high polymers even in strongly diluted solutions of ϵ‐caprolactone (0.2 mol/L and lower). The quantity and molecular mass of the polymers obtained decreased as the temperature increased. It was also established that the polymerization of the cyclic dimer of ϵ‐caprolactone is not initiated by KC24.