bluuebunny/crossref_metadata_2025_split huggingface dataset:
The chain configurational properties of novolak p‐cresol–formaldehyde resins
Authors: Tobiason Fred L. 
Published: April 2003

AbstractRotational isomeric state chain configurational analysis has been applied to the p‐cresol–form‐aldehyde chain structure. Steric interference allows the chain to be considered by using a twofold potential energy barrier. The bond rotational angles and conformational energies were set empirically to fit existing experimental dipole moment data, and the conformational angles were ±45° with a 132 cal/mole energy barrrier separating the g±g± from the g±g± rotational states. The data predict the existence of a cyclic tetramer in support of other researchers' experimental work. The limiting dipole moment ratio and characteristic ratio were computed to be 5.87 and 21.23, respectively. Support for this structure will have to wait for experimental data from higher‐molecular‐weight materials.
Esca applied to polymers. XXIII. RF glow discharge modification of polymers in pure oxygen and helium–oxygen mixtures
Authors: Clark D. T. , Dilks A. 
Published: April 2003

AbstractThe oxidation of polyethylene, polypropylene, and polystyrene by exposure to plasmas excited in pure oxygen and helium–oxygen mixtures at low power levels has been studied. A detailed curve resolution procedure is outlined, and the rate of oxidation is shown to be a strong function of the polymer structure for pure oxygen plasmas, as is the composition of the oxidized layer; this is not the case, however, for oxidation effected by helium–oxygen mixtures. It seems likely, from a consideration of the available data, that the oxidation is confined to the outermost monolayer and is initiated by a crosslinking mechanism that involves oxygen‐containing functionalities.
Electrochemical bulk polymerization of methyl methacrylate in the presence of nitric acid
Authors: Pistoia Gianfranco , Bagnarelli Ovidio 
Published: April 2003

AbstractThe electroinitiated polymerization of methyl methacrylate in the presence of nitric acid has been investigated on platinum and graphite anodes. The dependence of yields and molecular weights on parameters such as current density, temperature, speed of stirring, and HNO3 concentration was determined. Under continuous electrolysis conditions a stationary state takes place and the rate of polymerization exhibits zero order with respect to monomer and a 1.5 order with respect to current. On the other hand, under postpolymerization conditions a kinetic gel effect occurs, which limits the termination rate and leads to the typical acceleration in the conversion–time curves. The effect of postpolymerization is so marked, even after supplying small amounts of charge, that the formation of long‐lived radical chains is believed to be possible. In this respect HNO3 would play a fundamental role by stabilizing the growing radicals.
A reinvestigation of the chemical reactivity of N‐perfluoroacylaziridines
Authors: Demember John R. , Taylor Lloyd D. 
Published: April 2003

AbstractIt has been found that polymerization of perfluoroacylaziridine (1) occurs in the presence of acid. The polymers formed in the presence of acid have much higher uniformity of the unit structure and are of similar molecular weight to those obtained from anionic, or nucleophile‐initiated, polymerization of aziridine (1). The polymers formed from polymerization of aziridine (1) in the presence of acid provide an accessible route to linear unbranched polyethylenimine.
The photo‐ and electroinitiated polymerization of N‐vinyl phthalimide
Authors: Davies D. H. , Phillips D. C. , Smith J. D. B. 
Published: April 2003

AbstractTo elucidate mechanisms in electroinitiated polymerization reactions a comparison was conducted between ultraviolet (UV) photoinitiation and electroinitiation of N‐vinyl phthalimide with zinc chloride as a catalyst. Both methods give low yields of a complex polymer product. A detailed analysis, infrared (IR), gel permeation chromatography (GPC), elemental, and molecular weight, conducted on the polymeric products, indicated that phthalimide ring opening was occurring and that complex mixtures of poly(N‐vinyl phthalimide) derivatives were formed. Both initiation methods gave comparable results, which further indicated mechanistic similarity between photo‐and electroinitiation in these donor–acceptor charge transfer polymerizations.
Synthesis of polyamides by ring‐opening polyaddition of bis‐3,1‐benzoxazin‐4‐ones with aliphatic diamines
Authors: Ueda Mitsuru , Imai Yoshio 
Published: April 2003

AbstractOpen‐chain polyamides with inherent viscosities of 0.1–0.6 were prepared in nearly quantitative yields by the ring‐opening polyaddition of combinations of six bis‐3,1‐benzoxazin‐4‐one monomers and two aliphatic diamines in polar aprotic solvents at 80°C or below. The polymerization carried out in dimethyl sulfoxide at 80°C was best for preparing high‐molecular‐weight polymers. These polyamides were generally soluble in polar aprotic solvents, m‐cresol, and pyridine.
Synthesis of formamidine‐containing polymers from aromatic diamines
Authors: Mathias L. J. , Overberger C. G. 
Published: April 2003

AbstractAromatic polymers containing formamidine groups in the polymer backbone were obtained from aromatic diamines in high yields with α,α‐dichloromethyl ether and triethylorthoformate. The latter was the reagent of choice. Soluble, high‐molecular‐weight products were obtained with m‐phenylene diamine and 4,4′ bis(aminophenyl)methane. These polymers were characterized by viscosity, microanalysis, and nuclear magnetic resonance and infrared spectroscopy. Generally, insoluble products were obtained from p‐phenylene diamine and 2,6‐diaminotoluene, although small amounts of dimethylsulfoxide (DMSO)‐soluble fractions could be extracted and examined by NMR spectroscopy. IR analysis of the insoluble fractions confirmed formation of polymers with the formamidine‐containing structures. The synthetic procedures developed here make readily available this new class of aromatic polymers.
Plasma polymerization: An ESCA investigation of polymers synthesized by excitation of inductively coupled RF plasmas in isomeric difluoroethylenes
Authors: Clark D. T. , Shuttleworth D. 
Published: April 2003

AbstractThe polymers produced by glow discharge from three isomeric monomers are examined by ESCA. The polymer produced from 1,1‐difluoroethylene is discussed in some detail and compared with those prepared from the two 1,2‐difluoroethylene isomers. Charge distributions for the neutral molecules and their radical cations are calculated within the INDO SCF MO formalism and a possible reaction scheme that involves fluoroacetylene is outlined.
Pyrolysis of polyisoprenes. I. Differentiation between natural and synthetic cis‐1,4‐polyisoprenes
Authors: Gelling I. R. , Loadman M. J. , Sidek B. D. 
Published: April 2003

AbstractTwo methods of differentiating between natural rubber and synthetic cis‐1,4‐polyisoprenes have been examined. Both techniques depend on the presence of Ziegler‐Natta catalyst residues in the synthetic polymers. The major pyrolysis product of cis‐1,4‐polyisoprenes at 350°C is 1‐methyl‐4‐(1‐methylethenyl)cyclohexene. This can undergo disproportionation to yield 1‐methyl‐4‐(1‐methylethyl)benzene and methyl‐(1‐methylethyl)cyclohexenes. It is this disproportionation reaction, catalyzed by Ziegler‐Natta catalyst residues or by carbon black, that is responsible for the different product ratios obtained on pyrolysis of natural rubber and Ziegler‐Natta catalyzed cis‐1,4‐polyisoprenes. Lithium alkyl‐polymerized polyisoprenes undergo this secondary disproportionation reaction only in the presence of carbon black. Derivative thermogravimetric traces of black‐filled sulfur vulcanizates of natural rubber and synthetic polyisoprenes are significantly different because polymerization catalyst residues promote cyclization of the polymer.
Kinetics of radiation‐induced graft polymerization of styrene onto poly(ethylene oxide)
Authors: Omichi H. , Araki K. 
Published: April 2003

AbstractThe graft polymerization of styrene onto preirradiated poly(ethylene oxide) was studied. From the measurement of swelling of the polymer in various solvents the solubility parameter of poly(ethylene oxide) was estimated as 9.3. The kinetic analysis of the reaction indicated that the graft polymerization was diffusion controlled. Kinetic parameters of the reaction such as \documentclass{article}\pagestyle{empty}\begin{document}$\int_0^t {R_i} dt,k_{p,} k_{tr}$\end{document}, and kt were obtained in poly(ethylene oxide)‐styrene system and compared with those in poly(isobutylene oxide)‐styrene system.
Studies of the polymerization of diallyl compounds. XXII. Polymerization of diallyl oxalate in the evolution of carbon dioxide at elevated temperatures
Authors: Matsumoto Akira , Tamura Ikuo , Yamawaki Masataka , Oiwa Masayoshi 
Published: April 2003

AbstractThe polymerization of diallyl oxalate was conducted in the presence of radical initiators at a high temperature range of 80–180°C; a large decrease in degree of polymerization, an increase in residual unsaturation of the resulting polymer, and the evolution of carbon dioxide were observed with the elevation of temperature. These findings were reasonably interpreted by considering the dismutation of the uncyclized growing radical to yield the allyl radical, carbon dioxide, and polymer carrying a terminal double bond. The kinetics of the polymerization of diallyl oxalate in the evolution of carbon dioxide at elevated temperatures were also discussed in detail.
Monomer‐isomerization polymerization. XIX. Monomer‐isomerization copolymerizations of methylbutenes and 2‐butene with Ziegler‐Natta catalyst
Authors: Endo Kiyoshi , Otsu Takayuki 
Published: April 2003

AbstractThe copolymerization of 3‐methyl‐1‐butene (3M1B), 2‐methyl‐2‐butene (2M2B), or 2‐methyl‐1‐butene (2M1B) with trans‐2‐butene (2B) was attempted in the presence of a Ziegler‐Natta catalyst. It was found the 3M1B underwent monomer‐isomerization copolymerization with 2B to give a copolymer consisting of both 3M1B and 1‐butene (1B) units, with an infrared (IR) spectrum in good agreement with that obtained from the copolymerization of 3M1B with 1B under similar conditions. When the apparent copolymerization parameters obtained by a TiCl3–(C2H5)3Al catalyst were compared, the apparent reactivity of 3M1B observed in the 3M1B‐2B system was much higher than that in the 3M1B‐1B system. However, 2M2B and 2M1B did not undergo monomer‐isomerization copolymerization with 2B, and only the homopolymer of 1B was obtained under similar conditions.
Synthesis of wholly aromatic polysulfonamides from aromatic disulfonyl chlorides and aromatic diamines
Authors: Imai Yoshio , Ueda Mitsuru , Iizawa Takashi 
Published: April 2003

AbstractWholly aromatic polysulfonamides of high molecular weight were prepared by the solution poly‐condensation of aromatic disulfonyl chlorides with aromatic diamines in tetramethylene sulfone and substituted pyridines as the acid acceptor. Polysulfonamides with inherent viscosities as high as 1.2 were readily obtained by initiating polycondensation at a temperature of 5–10°C to control the side reactions. The polycondensation was fairly fast and was completed in 10 min at 60°C. All the aromatic polysulfonamides dissolved in a wide range of solvents, including acetone and tetrahydrofuran. These polymers were less thermally stable than the corresponding aromatic polyamides.
Fluorination of polyhydrofluoroethylenes. II. Formation of perfluoroalkyl carboxylic acids on the surface region of poly(vinylidene fluoride) film by oxyfluorination, fluorination, and hydrolysis
Authors: Shinohara Haruka 
Published: April 2003

AbstractOxyfluorination and postfluorination behaviors of poly(vinylidene fluoride) films, as well as hydrolysis of the films treated so far, have been studied by infrared (IR) spectrometry. By exposing the polymer film to a mixture of oxygen and fluorine at about 90°C acyl fluoride groups attendant on the scission of the polymer chains were formed. The oxyfluorinated molecules could be further perfluorinated with fluorine alone at about 90°C, leaving many of the acyl fluoride groups. When the properly oxyfluorinated and postfluorinated film was further treated with a hot 6M sodium hydroxide solution the opaque layer of perfluoroalkyl sodium carboxylate of high molecular weight was formed on the surface of the film, to about 3 μm in thickness, which behaved as a cation exchanger. This new type of cation exchanger of perfluoroalkyl carboxylic acid was significantly more acidic than the usual methacrylic acid exchanger. It was able to adsorb the sodium ions from a neutral sodium chloride solution up to about 70% of the exchange capacity and to keep the ions stable while washing them with water, though it could be regenerated to the hydrogen form with a dilute acetic acid solution. The nature of the new ion exchanger has been examined in some detail by IR spectrometry with Li+, Na+, and Cs+ ions.
Polysalt complexes of poly(vinylbenzo‐18‐crown‐6) and of poly(crown acrylate)s with polyanions
Authors: Varma A. J. , Majewicz T. , Smid J. 
Published: April 2003

AbstractMacrocyclic polyether or crown ether ester derivatives of acrylic and methacrylic acid were synthesized and polymerized. The cation binding properties of the polymers determined by extraction of picrate salts were similar to those obtained for poly(crown ether)s derived from styrene. In the presence of a crown‐complexable cation both polymers form insoluble polysalt complexes with sodium carboxymethylcellulose, potassium poly(styrene sulfonate), and potassium polyacrylate. The extent of precipitation depends on the type and concentration of cation as well as on the ratio polyanion to poly(crown ether). The precipitate appears to have an equal number of positive and negative charges. An insoluble hydrogen‐bonded complex is formed in the absence of salt when poly(vinylbenzo‐18‐crown‐6) and poly(acrylic acid) are mixed in 0.01M HCl. Organic solutes bound to the poly(crown ether)s, which occur in an aqueous mixture of poly(vinylbenzo‐18‐crown‐6) and picrate anions, are precipitated with the poly(crown ether) when the polysalt complex is formed.
Polymerization of vinylpyridinium salts. III. Further studies on the interfacial and isotropic polymerization of 4‐vinyl‐N‐methylpyridinium methylsulfate
Authors: Paleos C. M. , Evagelatos G. P. , Dais Photis , Kipouros G. 
Published: April 2003

AbstractIn the present study the polymerization of 4‐vinyl‐N‐methylpyridinium methylsulfate at liquid–liquid interfaces is investigated. Various experimental procedures that may favor the interfacial mode of polymerization over the isotropic one are discussed. The effectiveness of the methods was evaluated by physical characterization studies and particularly polymer tacticity. This last property is directly associated with the achieved organization of the monomers at interfaces. 13C‐NMR technique was used for tacticity determination. According to tacticity, random polymers are primarily obtained that result from an isotropic polymerization in the aqueous phase, where the monomer is extremely soluble. The small predominance of the syndiotactic triad over the isotactic one is explained by the occurrence of an interfacial polymerization induced by the orientation of the monomers. A polymerization model is proposed that justifies the stereospecificity modification of polymerization.
Kinetics of radiation‐induced graft copolymerization of styrene with ethyl acrylate
Authors: Omichi H. , Araki K. 
Published: April 2003

AbstractThe radiation‐induced graft copolymerization of styrene with ethyl acrylate onto preirradiated polyethylene powder was carried out at 20°C. The grafting yield decreased in the following order: ethyl acrylate ≫ styrene > styrene–ethyl acrylate mixture. On the other hand, the amount of absorption of liquid monomers in polyethylene powder decreased as follows: styrene > styrene–ethyl acrylate mixture > ethyl acrylate. By kinetic analysis of the grafting yield and amount of absorption of monomers it was elucidated that the value Kp/Kt in an ethyl acrylate system (7.7 × 10−2) was much larger than those in styrene–ethyl acrylate systems and in a styrene system (ca. 1.0 × 10−2).
Vinylhydroquinone. V. Tri‐n‐butylborane‐initiated copolymerization of maleic anhydride and redox property of copolymers
Authors: Iwabuchi Susumu , Watanabe Yasaku , Nakahira Takayuki , Kojima Kuniharau 
Published: April 2003

AbstractTri‐n‐butylborane (TBB) was found to be capable of initiating the copolymerization of vinylhydroquinone (VHQ) with maleic anhydride (MAn) and diethyl fumarate (DEF) in cyclohexanone at 30°C under nitrogen. Redox potentials of the VHQ–MAn copolymer obtained were examined. These results, along with spectroscopic data, indicate that the copolymers are of a highly alternating character.
Metallo esters. VII. Stabilizing effect of sodium tert‐butoxide on the growth center in the anionic polymerization of methacrylic esters
Authors: Lochmann L. , Kolařík J. , Doskočilová D. , Vozka S. , Trekoval J. 
Published: April 2003

AbstractThe growth center in the anionic polymerization of methacrylic esters is stabilized with alkaline alkoxides, sodium tert‐butoxide in particular. The lifetime of the growth center was investigated in the polymerization of methyl methacrylate by evaluating yield and molecular weight distribution of the polymer formed when the monomer was added in two doses. The average lifetime of the original growth center stabilized by sodium tert‐butoxide at 20°C under the given conditions was longer than several minutes. The stabilization of the growth center was also used in the stepwise copolymerization of n‐butyl methacrylate and methyl methacrylate. The copolymer thus obtained in high yield was characterized as a block copolymer on the basis of its solubility, nuclear magnetic resonance (NMR) spectra, and measurements of the complex shear modulus.
Graft copolymers of nucleic acid bases on polyethyleneimine: Interaction of the polymers
Authors: Overberger C. G. , Inaki Yoshiaki , Nambu Yoko 
Published: April 2003

AbstractInteractions of the graft copolymers of nucleic acid bases on polyethyleneimine with polynucleotides were studied. The backbone of the polymer is linear or branched polyethyleneimine. The nucleic acid bases are adenine and thymine. The polynucleotides used were polyadenylic acid (poly‐A) and polyuridylic acid (poly‐U). Interactions between these polymers were measured by ultraviolet (UV) absorption and the results were compared with the vinyl‐type nucleic acid model polymer.
Anionic polymerization. VI. Effect of polar modifiers on alkylsodium and alkylpotassium polymerization of butadiene
Authors: Halasa Adel Farhan , Cheng Tai Chun , Hall James E. 
Published: April 2003

AbstractIt was found that N,N,N′,N′‐tetramethylethylene diamine and hexamethyl phosphorus triamide minimize chain transfer reactions in the polymerization of 1,3‐butadiene in hydrocarbon solvent with alkylsodium or alkylpotassium initiators. The polymers obtained with alkylsodium initiators had a high molecular weight and high vinyl content at 90–95% conversion. The molecular weight of the polybutadiene made by alkylsodium and alkylpotassium initiators was dependent on the polymerization temperatures and modifier ratios, but the vinyl contents were independent of the modifier ratios. Vinyl contents of alkylpotassium‐initiated polymers showed a slight dependency on polymerization temperature; the vinyl contents of alkylsodium‐initiated polymers were independent of temperature. Addition of lithium tert‐butoxide and potassium tert‐amylate to these initiators in the presence of the modifiers affected the molecular weight but not the microstructure.
Radiation‐induced copolymerization of methyl trifluoroacrylate with ethylene
Authors: Matsuda Osamu , Watanabe Terutaka , Tabata Yoneho , Machi Sueo 
Published: April 2003

AbstractCopolymerization of methyl trifluoroacrylate (MTFA) with ethylene in bulk was induced by γ irradiation. The copolymerization was observed to proceed in the liquid monomer mixture of MTFA and ethylene at 25°C with the dose rates ranging from 5.0 × 104 to 1.0 × 106 rad/hr. A wide range of the initial monomer composition gives an almost equimolar and alternating copolymer. The highest polymerization rate was observed at the equimolar monomer composition. The dose rate exponent of the polymerization rate is unity. The reactivity ratios of r1 (MTFA) and r2 (ethylene) were determined to be 0.034 and 0.14, respectively.
Effect of solvent on the termination rate constant in initial stages of free radical polymerization
Authors: Mahabadi Hadi Kh. , Rudin Alfred 
Published: April 2003

AbstractThe effect of solvent on the termination rate constant Kt, in the initial stages of free radical polymerizations has been estimated by considering its effect on the viscosity of the medium and on the overall dimensions of the macroradicals. The expression derived predicts that Kt is inversely proportional to the viscosity of the reaction medium, η0, and that Kt, increases as the overall dimensions of the radicals decrease in poorer solvents. The effect of solvent on the η0Kt, product depends on the average size and concentration of polymer in the system. For relatively high concentrations of high‐molecular‐weight polymers η0Kt can be greater in a better solvent than in a poorer solvent. This trend would be reversed for low concentrations and/or low polymer molecular weights. Good agreement has been found between experimental and estimated values of η0Kt.
Synthesis of polyacylsulfonamide‐amides by ring‐opening polyaddition of N,N′‐arylenedisulfonylbissuccinimides with diamines
Authors: Imai Yoshio , Ueda Mitsuru , Okuyama Kazuo 
Published: April 2003

AbstractRing‐opening polyaddition of N,N′‐arylenedisulfonylbissuccinimides with both aliphatic and aromatic diamines in N‐methyl‐2‐pyrrolidone at room temperature afforded polyacylsulfonamide‐amides having inherent viscosities in the range of 0.2–0.4 in excellent yields. The polymers revealed acidic nature and were readily soluble in both polar aprotic solvents and basic media. They melted at a temperature below 200°C and began to decompose at around 250°C in nitrogen.
Binding the hydrophobic fluorescent probe, 2‐p‐toluidinylnaphthalene‐6‐sulfonate, by polycations that contain apolar pendant groups: Equilibrium dialysis and fluorescence measurements
Authors: Takagishi Toru , Naoi Yozo , Kuroki Nobuhiko 
Published: April 2003

AbstractThe thermodynamic parameters for the interaction of the hydrophobic fluorescent probe, 2‐p‐toluidinylnaphthalene‐6‐sulfonate (TNS), and polycations that contain a piperidinium cation and various nonpolar pendant groups were calculated. Binding is exothermic and involves a positive entropy gain. The contribution of the entropy term to the free energy change tends to increase with increasing hydrophobicity of the polymers. The intensity of the fluorescence of TNS is enhanced when the probe binds to the polycations. The nature and phenomena of hydrophobic fluorescent probe binding with the polymers are discussed.
Pyrolysis/chemical ionization mass spectrometry of polymers
Authors: Shimizu Yukio , Munson Burnaby 
Published: April 2003

AbstractPyrolysis/mass spectrometric studies have been made on polystyrene, poly(vinyl chloride), and poly(methyl methacrylate) with electron ionization (EI) and chemical ionization (CI) mass spectrometry and a variable temperature probe for direct insertion into the source of the mass spectrometer. Similar results obtained with EI and CI mass spectrometry are in agreement with previous experiments. Advantages of the simplification of spectra in the CI made, as well as the advantages of using both techniques for identification of pyrolysis products, are discussed.