bluuebunny/crossref_metadata_2025_split huggingface dataset:
Room‐temperature polycondensation of β‐amino acid derivatives. V. Synthesis of hydrophilic polyamide by the polycondensation of β‐amino acid derivatives
Authors: Sanui K. , Ogata N. 
Published: April 2003

AbstractN‐(Hydroxyalkyl) β‐alanine ester which was obtained from amino alcohol and acrylate yielded polyamide at room temperature in the presence of a basic catalyst. Alkali and alkali earth metal alkoxides had a strong catalytic effect on the room‐temperature polycondensation of N‐(hydroxyethyl)‐β‐alanine esters. The catalytic activity of metal alkoxides decreased in the order: Li > Na > K > Cs and Ca > Zn > Mg. Aluminum and titanium alkoxide had a weak catalytic effect, while boron (III), tin (IV), antimony (V), and tellurium (VI) alkoxides did not show any catalytic activity for the polycondensation. It was also found that solvent had an effect on the course of the polycondensation of N‐(hydroxyethyl)‐β‐alanine esters, and the highest molecular weight polymer was formed only in methanol solution. The solid‐phase polycondensation of the low molecular weight prepolymer resulted in a high molecular weight polymer with an inherent viscosity of 1.0 in the presence of a catalytic amount of phosphoric acid. The polymer obtained is hydrophilic and its moisture absorption is more than twice that of nylon 6.
New method for preparing saturated and unsaturated aliphatic polyurethanes
Authors: Miyake Yasuhiko , Ozaki Shoichiro , Hirata Yoshio 
Published: April 2003

AbstractSaturated and unsaturated aliphatic polyurethane were obtained from three different routes. In route 1, 1,4‐dichloro‐2‐butene, sodium cyanate, and methanol were reacted to give dimethyl 2‐butene‐1,4‐dicarbamate. This is hydrogenated easily to give dimethyl butane‐1,4‐dicarbamate. Ester exchange reaction of this compound with glycol gave saturated aliphatic polyurethane. In another procedure, route 2, 1,4‐dichloro‐2‐butene, sodium cyanate and excess glycol were reacted to give bis(ω‐hydroxyalkyl)‐2‐butene‐1,4‐dicarbamate. This was hydrogenated to give bis(ω‐hydroxyalkyl)‐butane‐1,4‐dicarbamate. A glycol elimination reaction gave poly(polymethylene tetramethyl‐enedicarbamate). By route 3, 1,4‐dichloro‐2‐butene, sodium cyanate, and glycol were reacted to give poly(polymethylene 2‐butene‐1,4‐dicarbamate), a new unsaturated aliphatic polyurethane.
Polymerization of 3,4‐dihydro‐2H‐carboxyaldehyde (acrolein dimer). Part II. Copolymerization with isocyanates
Authors: Kitahama Yoshiharu , Ohama Hiroshi , Kobayashi Hidehiko 
Published: April 2003

AbstractCopolymers of 3,4‐dihydro‐2H‐pyran‐2‐carboxyaldehyde (acrolein dimer) with phenyl isocyanate were obtained under several conditions. Infrared and NMR analyses showed that the isocyanate always reacted with acrolein dimer forming urethane linkages, not block units of isocyanate. An alternating copolymer was obtained from the copolymerization in the presence of anionic catalysts such as butyllithium at room temperature, irrespective of the monomer ratios employed. The isocyanate content in the copolymer prepared with an Al(C2H5)2Cl catalyst was increased by elevating polymerization temperature. The copolymerizability of aldehydes with the isocyanate depends upon the polarity of aldehyde group.
Energy transfer and radiolytic product formation in the system polystyrene–pyrene
Authors: Wilske J. , Heusinger H. 
Published: April 2003

AbstractIn γ‐radiolysis of polystyrene at room temperature, the formation of radicals detected by ESR spectroscopy is greatly reduced in the presence of pyrene, while crosslinking and hydrogen production are almost unchanged. The formation of these radicals was shown to start from the first excited singlet state of polystyrene competing with radiationless energy transfer to pyrene. Crosslinking and hydrogen production, on the other hand, are independent of the formation of these radicals and attributable to hot hydrogen or ion‐molecule reactions. Besides energy transfer from polystyrene to pyrene by dipole–dipole interaction the results indicate that intramolecular energy transfer within polystyrene is present.
Electron spin resonance study of radiation degradation of polytetrafluoroethylene
Authors: Hedvig Péter 
Published: April 2003

AbstractElectron spin resonance measurements were performed at different stages of radiation degradation of polytetrafluoroethylene. It was found that under radiation, peroxy radicals were transformed into chain‐end fluorocarbon radicals, which in turn became into chain‐side radicals. On the basis of these data, a scheme for the degradation mechanism is given.
Reaction of nitrogen dioxide with polystyrene films
Authors: Jellinek H. H. G. , Flajsman F. 
Published: April 2003

AbstractThe reaction of nitrogen dioxide with thin polystyrene films has been investigated at 35°C with different partial pressures of NO2 (0.1, 2, 15, 30, and 60 cm Hg) and at several temperatures (25, 35, 45 and 55°C). The films were thin enough (ca. 20 μ) so that the reaction was independent of the diffusion of gas into the polymer. The experimental results can be represented by a chain mechanism. The whole degradation process is controlled by the diffusion of polymer radicals out of cages. This diffusion in turn, is affected by the decrease in viscosity or decrease in weight‐average molecular weight as degradation proceeds. This leads to an acceleration of the degradation process. A straight‐line relationship between the logarithm of the reciprocal weight‐average molecular weight and the logarithm of a reaction–time function was found. The dependence on the rate was substantiated by degrading polymer fractions. The energy of activation for the process is small, in agreement with a diffusion process for chain scission. Nitro and nitrite groups are incorporated along the backbone of polystyrene during exposure. The number of these polar side groups appears to pass through a maximum with time, as is evidenced by aggregation of polymer molecules in benzene solution only during the middle stage of the degradation. The final stage of the process is slowed down by retarder being produced. This retarder can be removed by reprecipitation of exposed polymer films. Degradation in solution is similar to that of films. Isotactic polystyrene shows less irregularities in its degradation curve than the atactic polymer. This is, presumably, due to its more homogeneous morphology, large molecular weight, and broader molecular size distribution. The plot of the degree of degradation versus time for the isotactic polymer can be satisfactorily approximated by a straight line.
Kinetics of the reverse Diels‐Alder reaction of dicyclopentadienecarboxylate groups on cotton cellulose
Authors: Franklin W. E. , Mack C. H. , Rowland S. P. 
Published: April 2003

AbstractCotton cellulose in the form of fabric has been esterified with dicyclopentadienecarboxylic acid to a degree of substitution of 0.44. The kinetics of the reverse Diels‐Alder reactions of the dicyclopentadienyl groups of the resulting cellulose ester in the presence of trapping agents and of swelling and nonswelling liquids have been measured with the differential scanning calorimeter. Fiber width measurements indicate that the esterified cotton fibers are swollen in the presence of the trapping agents dibutyl maleate, N‐phenylamaleimide, and N‐phenylmaleimide in tetraglyme solution, and in the presence of the nonreactive swelling agents tetraglyme and glycerol. The activation parameters for the dissociations in the swollen fibers are: Ea = 28–33 kcal/mole and ΔS* = −5 to +5 e.u. These kinetic parameters are similar to those previously found for the dissociation of methyl dicyclopentadienecarboxylate in solution. Fiber width measurements indicate that the esterified cotton fibers are collapsed in the dry state and in the presence of paraffin oil, deposited Carbowax 6000, or deposited glyceryl tristearate. The activation parameters for the dissociations in the collapsed fibers are Ea = 18–24 kcal/mole and ΔS* = −20 to −30 e.u. The kinetics are discussed in terms of the state of the cellulose matrix in the swollen and in the collapsed fibers.
Spin‐probe studies. I. Applications to latexes and micelle characterization
Authors: Rabold Gary Paul 
Published: April 2003

AbstractThe interaction of sodium dodecyl sulfate (NaDS) with styrene—butadiene latexes was investigated by application of the recently developed spin‐probe technique. It is possible by this method to detect the presence of micelles in a latex reasonably quantitatively. The effective surface area occupied per molecule of soap was calculated to be 53 Å2. Differences in purity can readily be detected for several NaDS samples. The less pure samples show a lower critical micelle concentration (CMC) and a significantly more ordered micelle structure. The addition of hexane to NaDS solutions above the CMC leads to a greater immobilization of the spin probe. This is interpreted as reflecting a tighter packing of the soap molecules. The addition of ethanol, acetic acid, and acrylic acid leads to a looser association of the probe with the micelles. The micelles catalyze the decomposition of the nitroxide probe in the presence of organic acids. The aggregation of sodium deoxycholate was also conveniently followed by the spin‐probe method.
Polysiloxanes having aromatic heterocyclic units. I. Polydimethylsiloxane benzimidazole polymer
Authors: Nakajima Toshinari , Marvel C. S. 
Published: April 2003

AbstractA polymer containing dimethylsiloxane units (35) and benzimidazole units (1) has been prepared by the condensation of 3,3′‐diaminobenzidine and an α,ω‐bis‐(γ‐carboxy‐n‐propyl) polydimethylsiloxane. The new polymer has some rubbery properties, but it decomposes catastrophically at 400°C.
Vinyl polymerization photosensitized by anthraquinone sulfonates in aqueous solutions
Authors: Anwaruddin Q. , Santappa M. 
Published: April 2003

AbstractThe kinetics of the photopolymerization of the vinyl monomers MMA and MA sensitized by anthraquinone sulfonate‐NaCl‐HClO4 systems have been studied systematically. The wavelength 365 mμ was used for irradiation. Sodium anthraquinone‐2‐sulfonate and disodium anthraquinone‐2,6‐disulfonate were used as sensitizers, and all experiments were conducted in deaerated conditions. The polymerization was followed by the measurement of monomer disappearance (gravimetrically), rate of sensitizer disappearance (spectrophotometrically) and the chainlength of the polymer formed (viscometrically). Monomer concentration, kε, [NaCl], and I were varied. In the light of the experimental results a prima facie kinetic scheme was proposed. The specific rate constants for the various steps have been evaluated.
Polymers of 2‐vinyl‐1,3‐dioxolanes
Authors: Nordstrom J. David 
Published: April 2003

AbstractLewis acid‐initiated polymerizations of 2‐vinyl‐1,3‐dioxolanes have been studied. Evidence is presented showing at least three types of structural units in the polymer. Polymerization is propagated by 1,2 addition, by acetal ring opening, and by rearrangement, ring opening mechanisms. Polymerization is accompanied by the formation of a dimer consisting of a 1,4‐dioxepane and 1,3‐dioxolane ring. Film formers from methacrylate esters of vinyl dioxolane compounds are also described.
Role of polymer oxidation in the adhesion of polyethylene to metals
Authors: Sykes J. M. , Hoar T. P. 
Published: April 2003

AbstractUntreated polyethylene will adhere well to aluminum only if it is applied in an oxidizing atmosphere. Peel strengths for coatings applied to various bright copper surfaces are far lower, probably because of decrease in polymer oxidation when copper is present. Preoxidized polyethylene sheet adheres well when melted on to copper in nitrogen. In view of earlier evidence for the formation of a weak interfacial layer containing shortchain material, it is proposed that the weak bond strengths so caused are substantially improved by the preferential adsorption of longer‐chain surface‐active oxidized species in the polymers.
Structure and properties of cellulose graft copolymers. III. Cellulose–methyl methacrylate graft copolymers synthesized by the ceric ion method
Authors: Huang Robert Y. M. , Chandramouli P. 
Published: April 2003

AbstractThe ceric ion‐initiated graft copolymerization of methyl methacrylate onto wood cellulose was found to depend on the concentrations of initiator, monomer, and cellulose. The structure of cellulose—methyl methacrylate graft copolymers was studied by hydrolyzing away the cellulose backbone to isolate the grafted poly(methyl methacrylate) branches. The molecular weights and molecular weight distributions of the grafted poly(methyl methacrylate) were determined by using gel‐permeation chromatography. The number‐average (M̄n) molecular weights ranged from 36 000 to 160 000 and the polydispersity ratios (M̄w/M̄n) varied from 4.0 to 7.0. The grafting frequency or the number of poly(methyl methacrylate) branches per cellulose chain calculated from the per cent grafting and molecular weight data varied from 0.38 to 3.2. The structure of cellulose—methyl methacrylate graft copolymers and the effect of stepwise addition of initiator on the structure are discussed.
Vinyl polymerization with Fe(III)‐thiourea as initiator system. Part I. General features and kinetics of Fe(ClO4)3‐thiourea reaction
Authors: Mandal B. M. , Nandi U. S. , Palit S. R. 
Published: April 2003

AbstractInitiation of polymerization of methyl methacrylate, styrene, and acrylonitrile with the redox system Fe(III)—thiourea has been examined. For the heterophase polymerization any of the ferric salts, such as FeCl3, Fe2(SO4)3, and Fe(ClO4)3 can be used as oxidant, but there is no polymerization in the homogeneous phase when FeCl3 is used as oxidant. It was also observed that Fe(ClO4)3 retards the radical polymerization of styrene, though this salt has hardly any effect on the radical polymerization of methyl methacrylate. Further, the reaction between Fe(ClO4)3 and thiourea was found to be kinetically of second order. The rate is largely influenced by the nature of the solvent. It is concluded that apart from the dielectric constant of the solvents, specific effects like complex formation of Fe(III) with solvents should have a marked influence on the rate of this reaction.
Thermal stabilities of homopolymers of amino acids
Authors: Obata Hiroko , Ogawa Shigeo 
Published: April 2003

AbstractIn order to study the thermal stabilities of the α‐helical polyamino acids in the solid state, measurements of the infrared spectra at high temperature, weight loss by thermogravimetry, and the expansion of the α‐helix by x‐ray diffractometry were carried out on poly(γ‐methyl D‐glutamate), poly(γ‐benzyl L‐glutamate), poly‐L‐alanine, poly(β‐benzyl L‐aspartate), poly‐δ‐carbobenzoxy‐L‐ornithine and poly‐ε‐carbobenzoxy‐L‐lysine. The thermal degradation temperatures of these polymers lie between 140°C and 230°C. The α‐helical conformation is stable at high temperature in these polyamino acids, except for poly(β‐benzyl L‐asparatate), unless thermal degradation takes place. As temperature rises, the amide A and the amide I bands of the infrared spectra shift slightly to higher frequencies and the amide II band to lower frequencies. At the same time, the intensities of these amide bands decrease. These changes differ among the different molecules. From the x‐ray measurement, it was found that the α‐helix expands along the helical axis with temperature. It is expected that the intramolecular hydrogen bonds of the α‐helix become weak with increasing temperature and that the state of the hydrogen bonds of the α‐helices depends upon the molecules.
Studies of Japanese lacquer: Urushiol dimerization by the coupling reaction between urushiol quinone and a triolefinic component of urushiol
Authors: Kato Takashi , Kumanotani Ju 
Published: April 2003

AbstractPreviously, the formation of urushiol quinone from urushiol was demonstrated in the laccase‐catalyzed oxidation process of the sap of the Japanese lacquer tree (Rhus vernicifera D.C.) or of lacquer formed from it. This paper presents the results of the investigation on the participation of urushiol quinone in the oxidative polymerization and crosslinking of the sap or the lacquer. The polymeric urushiol was obtained by the fractionation of the mildly oxidized sap (Japanese lacquer), and a specific dimeric urushiol was isolated from it by thin‐layer chromatography (TLC). Structural analysis of the dimer illustrated that it has a conjugated triene structure and may be formed by a coupling reaction between urushiol quinone and a triolefinic component of urushiol. Further support for this was given by the spectroscopic study of the reaction between 4‐tert‐butyl‐o‐quinone and the triolefinic component of dimethylurushiol, and by the isolation and identification of the coupling product between them.
Polymerization of tetrahydrofuran: A radiochemical study of the initiation mechanism
Authors: Pasika Wallace M. , Wynn John W. 
Published: April 2003

Abstract14C‐tagged triphenylmethyl hexachloroantimonate was used to initiate the polymerization of THF. An activity count on the polymers indicated no incorporation of initiator fragments into the macromolecule. On ascertaining the fate of the tagged trityl fragment it was found that the activity resided in the triphenylmethane isolated from the methanol supernatant. This indicates that at least one sequence of the initiation reaction in this polymerization involves hydride ion abstraction.
Synthesis of polymerizable tetrafluorohydrazine–diene addition compounds
Authors: Reed Samuel F. 
Published: April 2003

AbstractThe reaction of tetrafluorohydrazine with alkenyl acrylates and methacrylates under appropriate conditions resulted in the isolation of olefinic bis(difluoramines) capable in some instances of undergoing free‐radical‐initiated polymerization and copolymerization. Monomer and polymer synthesis and characterization are discussed.
Thermal decomposition products of polypropylene
Authors: Tsuchiya Yoshio , Sumi Kikuo 
Published: April 2003

AbstractIsotactic polypropylene was decomposed under vacuum at 360, 380, and 400°C, and the volatile products from C1 to C12 hydrocarbons were analyzed by gas chromatography. The formation of the main products is discussed on the basis of a free‐radical mechanism in which intramolecular radical transfer is assumed to play an important role. The mechanism of the formation of a number of products suggested by previous workers is criticized on the basis of the results of a more comprehensive analysis of this investigation.
Gel‐permeation chromatography of cellulose esters. Effect of average DP, DS, substituent size, and primary hydroxyl content
Authors: Brewer R. J. , Tanghe L. J. , Bailey S. 
Published: April 2003

AbstractHydrolyzed cellulose acetates and cellulose tripropionates prepared over wide ranges of intrinsic viscosity (DP) were fractionated by gel‐permeation chromatography (GPC). An increase was observed in the polystyrene equivalent length (PSEL) at 50% cumulative height with increasing DP of the ester. Cellulose acetates and propionates over wide range of acyl content (DS), and a homologous series of triesters (propionate through heptanoate) of the same DP were fractionated by GPC. Increased amount and size of acyl gave relatively small increases in PSEL. The molecular size of cellulose acetates was not affected by the amount of primary hydroxyl present in the esters. The breadth of molecular weight distribution of the cellulose esters, as measured by the weight‐average to number‐average molecular size ratio, M̄w/M̄n, was not affected by any variation in the composition of the esters. A blend of cellulose tripropionates of widely differing DP gave a broadened GPC curve in agreement with that calculated from the components of the blend.
Radiation‐induced solid‐state polymerization of derivatives of methacrylic acid. III. An electron spin resonance study of radical reactions in irradiated octadecyl methacrylate
Authors: Bowden M. J. , O'Donnell J. H. 
Published: April 2003

AbstractThe electron spin resonance spectrum of gamma‐irradiated octadecyl methacrylate (m.p. ≈ 12°C.) was due to a mixture of three radicals formed by (1) loss of a hydrogen atom from the paraffin chain, (2) addition of a hydrogen atom to the double bond, and (3) addition of a monomer molecule to radicals formed by (1) or (2). On warming monomer added to radicals (1) and (2) between −170 and −50°C., and above −50°C. the spectrum was solely due to propagating methacrylate radicals. The total radical concentration decreased slightly at −150°C. and was then constant up to −30°C. A marked decrease in radical concentration occurred from −30 to +12°C., it took place rapidly and reached an equilibrium value after each successive increase in temperature. Differential thermal analysis indicated a solid—solid phase change at −30°C. When the sample was kept at 0°C. there was no further decrease in radical concentration even with 50% conversion to polymer. With 2% added chloranil the (chloranil)− was observed to be of about the same concentration as methacrylate radicals. The initial total radical concentration was lower and decreased to zero by 0°C. on warming. No polymer was obtained.
Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. II. Properties of acrylonitrile–styrene copolymer
Authors: Yabumoto Shigeru , Ishii Kiyoshi , Kawamori Masakiyo , Arita Koichiro , Yano Hiroshi 
Published: April 2003

AbstractThe properties of the acrylonitrile–styrene copolymer prepared in the presence of zinc chloride were investigated in comparison with those of a copolymer having the same overall composition and prepared by the ordinary radical procedure. The characteristics of the polymer prepared with ZnCl2were as follows: (1) less coloration by alkali treatment, (2) less coloration by thermal treatment and (3) higher glass transition temperature. These features may be attributed principally to the structure of the copolymer, which has more unlike bonds and less long sequences as described in the first article of this series. The effects of residual salt in the copolymer on the properties were also investigated.
Molecular weight distribution in radiation‐induced polymerization. I. γ‐radiation‐induced free‐radical polymerization of liquid styrene
Authors: Huang R. Y. M. , Westlake J. F. , Sharma S. C. 
Published: April 2003

AbstractThe kinetics of γ‐radiation‐induced free‐radical polymerization of styrene were studied over the temperature range 0–50°C at radiation intensities of 9.5 × 104, 3.1 × 105, 4.0 × 105, and 1.0 × 106 rad/hr. The overall rate of polymerization was found to be proportional to the 0.44–0.49 power of radiation intensity, and the overall activation energy for the radiation‐induced free‐radical polymerization of styrene was 6.0–6.3 kcal/mole. Values of the kinetic constants, kp2/kt and ktrm/kp, were calculated from the overall polymerization rates and the number‐average molecular weights. Gelpermeation chromatography was used to determine the number‐average molecular weight M̄n, the weight‐average molecular weight M̄w, and the polydispersity ratio M̄w/M̄n, of the product polystyrene. The polydispersity ratios of the radiation‐polymerized polystyrene were found to lie between 1.80 and 2.00. Significant differences were observed in the polydispersity ratios of chemically initiated and radiation‐induced polystyrenes. The radiation chemical yield, G(styrene), was calculated to be 0.5–0.8.