bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of β‐cyanopropionaldehyde. X. Anionic copolymerization with methyl isocyanate
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi 
Published: April 2003

AbstractAnionic copolymerization of β‐cyanopropionaldehyde (M1) with methyl isocyanate (MeI, M2) was studied with use of benzophenone–dilithium complex as initiator at −78°C. The values of monomer reactivity ratio were determined to be r1 = 8.3 ± 0.3 and r2 = 0.01 ± 0.01. The structure of resulting copolymer was investigated by means of NMR analysis. The MeI unit is presumed to enter the copolymer chain through its CN opening.
Utilization of oxygen difluoride for syntheses of fluoropolymers
Authors: Toy Madėline S. 
Published: April 2003

AbstractThe utilization of OF2, for chain extension of polyperfluoropolyenes, insertion of functional groups into the polymer structure and addition copolymerization with perfluorodiene is described. The results of reactions of OF2 and polyperfluoro‐1,2‐ and ‐1,4‐butadiene indicate that conditions can be selected either to extend the polymer chain or to insert acyl fluoride groups into the polymer structure. Ambient and higher temperatures favor insertion of acyl fluoride groups. At 0°C chain extension occurs without introduction of acyl fluoride groups. Preliminary results on the novel synthesis of perfluoroalkylene oxide polymer by addition copolymerization of perfluorobutadiene and OF2 is also reported.
Cationic copolymerization of tetrahydrofuran with epoxides. II. Characterization and gel‐permeation chromatography of by‐products formed during polymerization
Authors: Hammond J. M. , Hooper J. F. , Robertson W. G. P. 
Published: April 2003

AbstractThe cyclic oligomers formed as by‐products in the polymerization of propylene oxide. 1,2‐butylene oxide, and n‐propyl glycidyl ether, and in the copolymerization of these monomers with tetrahydrofuran have been studied by gel‐permeation chromatography and otherwise and their structures have been determined. Some of the physical properties of the cyclic oligomers are described.
Cationic copolymerization of tetrahydrofuran with epoxides. III. Synthesis of block copolymers
Authors: Hammond J. M. , Hooper J. F. , Robertson W. G. P. 
Published: April 2003

AbstractPolymerization of various cyclic ethers by BF3·O(C2H5)2 in the presence of polymeric glycol leads to the formation of hydroxyl terminated block copolymers. Where poly(oxyethylene glycol) is used as the polymeric glycol, fission of the poly(oxyethylene glycol) chain occurs, and block copolymers, containing shorter ethylene oxide unit sequences are obtained. With poly(oxypropylene glycol), on the other hand, the polymer chain remains intact. This may be due to the steric influence of the pendant methyl groups. The cyclic oligomers formed as by‐products in the polymerizations are easily removed.
Thermal reactions of N,N′ bis(p‐nitrophenyl)sulfamide and p‐benzoquinone dioxime–acid mixtures
Authors: Riccitiello S. R. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractN,N′ Bis(p‐nitrophenyl)sulfamide and p‐benzoquinone dioxime–acid mixtures were found to undergo an abrupt reaction when heated to give a black polymeric material. These polymeric materials exhibited thermal stability (TGA in N2) up to 500°C and were insoluble in all solvents including hot concentrated sulfuric acid. From analytical data, structural formulae have been assigned to the polymeric materials that are logically derivable from the starting materials.
Structure of polymers obtained from sulfur monochloride and olefins containing sulfonium salt structures
Authors: Lautenschlaeger F. 
Published: April 2003

AbstractReactions of sulfur monochloride with diolefins lead to polymeric products which can be reduced to diepisulfides in low yield. In reactions with cyclic triolefins, polymers containing tricyclic sulfonium structures are obtained as a results of transannular additions and subsequent transannular displacements. Due to the insolubility and reactivity of these ionic structures, only incomplete structural assignements could be made, but the reactions are studied on similar cyclic structures which provide model systems.
Partial ladder polymers with anthraquinone units. Reaction of 1,2,5,6‐tetraaminoanthraquinone with p‐benzoquinone derivatives
Authors: Szita J. , Marvel C. S. 
Published: April 2003

Abstract1,2,5,6‐Tetraaminoanthraquinone has been condensed with 2,5‐diaminobenzoquinone, 2,5‐diaminobenzoquinone diimide, and 2,5‐diaminohydroquinone to give partial ladder polymers which are only slightly soluble in sulfuric acid and do not produce soluble products on reduction with sodium dithionite in alkaline media.
Ziegler polymerization of olefins. IX. Donor effects in metal alkyl‐free and Ziegler‐type stereospecific catalysts
Authors: Boor J. 
Published: April 2003

AbstractElectron donors, especially trialkylamines and azulene, have been examined in aluminum alkyl‐, CH3TiCl3‐ and hydrogen‐activated TiCl3 catalysts for the polymerization of propylene to isotactic polymer. A comparison and an evaluation were made with findings which were established earlier with zinc alkyl‐based TiCl3 catalysts. We find that the donor, when it is present in low concentrations in all of the above catalysts, can inactivate preferentially the less stereoregulating sites. In this way the isotactic content and the molecular weight of the polymer are increased, but only at the expense of a lower catalyst activity. The addition of hydrogen to the TiCl3–donor catalyst at −78°C produced a threefold effect: (1) the activity of the catalyst was increased about 5 to 15 times and higher, (2) the polypropylene formed with this more active catalyst was more isotactic (ca. 10–15%), and (3) the polymer had a lower molecular weight. It is proposed that the increase in catalyst activity was due to the generation of Ti‐H bonds to which propylene molecules then added, the Ti‐H bonds thus being transformed into active Ti‐C centers.
Structure and reactivity of α,β‐unsaturated ethers. XIII. Cationic copolymerization and acid‐catalyzed hydrolysis of 1,2‐dialkoxyethylenes
Authors: Okuyama Tadashi , Fueno Takayuki 
Published: April 2003

AbstractThe cationic copolymerizations of geometrical isomers of 1,2‐dimethoxy‐ and 1,2‐diethoxyethylenes with vinyl isobutyl ether as a reference monomer have been carried out in methylene chloride at −70° using boron trifluoride etherate as catalyst. The kinetics of the acid‐catalyzed hydrolysis of these ethers has also been investigated in 80% aqueous dioxane, in order to compare the results with the polymerizabilities. It has been found that the cis ethers are ca. four times as reactive as their trans isomers in both reactions. On the other hand, it has been proved that a β‐alkoxyl substitution reduces the hydrolysis reactivity of vinyl alkyl ethers by a factor of ca. 10−3 while it even enchances the cationic polymerizability. These contrasting results are interpretable from the nature of the transition states which are different for the two reactions.
Modification of poly(vinyl chloride). XIII. Crosslinking of poly(vinyl chloride) with dithiols and properties of the crosslinked products
Authors: Mori Kunio , Nakamura Yoshiro 
Published: April 2003

AbstractPVC was crosslinked by immersing PVC–dithiol blends in ethylenediamine at 30°C. Properties of the products depended on the chain length and chemical structure of the crosslinkage and on the molecular weight of the polymer chain between crosslinks Mc. Crosslinking by the agent of soft structure and long molecular chain resulted in high tensile strength at break and impact strength and low brittle temperature. The use of the crosslinking agent of short molecular chain gave high yield strength, Young's modulus, and heat distortion temperature. The relation of Mc and the chemical structure of the crosslinks to the properties of the crosslinked rigid polymer was discussed in regard to the crosslinking effect and plasticizing effect.
Use of phosphite amides in the synthesis of polyamides
Authors: Overberger C. G. , Veneski R. A. , Šebenda Jan 
Published: April 2003

AbstractThe preparation of polyamides by the phosphite amide procedure was investigated. The yield of amidation was determined in the reaction of diethyl‐ or o‐phenylenephosphite derivatives of piperidine, piperazine, or trans‐2,5‐dimethylpiperazine with either mono‐ or dicarboxylic acids. Higher yields were obtained by using diethyl phosphite derivatives; however, for both types of derivatives the yields were never greater than 90%. Only low molecular weight polymers could be obtained under optimum reaction conditions. In the polycondensation of (+)‐trans‐1,3‐cyclohexanedicarboxylic acid or (+)‐trans‐1,2‐cyclohexanedicarboxylic acid with phosphite derivatives of either piperazine or trans‐2,5‐dimethylpiperazine, the optical rotation of the polymers was lower than the rotation of the corresponding polyamides prepared by the interfacial condensation procedure with dicarboxylic acid chlorides. It was shown that an intermediate mixed anhydride was formed during the amidation reaction. This may account for the observed racemization.
NMR identification of C11 to C40 branched hydrocarbons derived from the decomposition of polyisobutylene
Authors: Warren R. W. , Gates D. S. , Driscoll G. L. 
Published: April 2003

AbstractThe composition of nonvolatile fluids obtained from thermally cracking and hydrogenating polyisobutylene was determined by using a combination of gas chromatography and nuclear magnetic resonance spectroscopy (NMR). This work involved the separation and characterization of a homologous series, C11–C40, of sixteen branched hydrocarbon species consisting of repeating isobutylene structures. As a result of this investigation, useful correlations between NMR spectra and molecular structure for highly branched hydrocarbons were developed. The data demonstrate that these hydrocarbons are unique species characterized by “crowded” and sterically hindered geminal methyl and isolated methylene groups. NMR solvent shift studies in benzene solutions indicate that it is possible to differentiate between maximally crowded geminal methyl groups and between maximally crowded methylene groups in these structures. Results of the benzene‐induced solvent effects are discussed with respect to the stereochemistry of these molecules and related to existing solvent shift data. These results suggest that these hydrocarbons are polar or nearly polar materials. Successive losses of isobutylene units from stabilized tertiary radicals can account for the formation of the major species identified in these fluids. Higher carbon numbered species have lower refractive indices and densities and higher molal volumes than predicted by calculations.
Propagation rate constant in cationic polymerization of cyclic dienes. I. Polymerization of cyclopentadiene with titanium tetrachloride–trichloroacetic acid
Authors: Kohjiya S. , Imanishi Y. , Higashimura T. 
Published: April 2003

AbstractCationic polymerization of cyclopentadiene induced by titanium tetrachloride–trichloroacetic acid was investigated in a toluene solution at −69 to −77°C. All manipulations were handled under vacuum conditions. Time–conversion curves were determined accurately by following the exothermicity of the fast reaction in an adiabatic system. The polymerization kinetics were developed on the basis of a fast initiation reaction and a nonstationary‐state concentration (diminishing concentration) of active species, and the propagation rate constant k2 was determined by substituting either an initial rate of polymerization or a final conversion for the kinetic equations. k2 for the present system was determined to be 350 l./mole‐sec, which is larger than those so far reported for some vinyl monomers in cationic polymerization. The present method can be commonly applied to reactive monomers for the determination of k2. The nature of termination reaction is discussed in connection with the determination of k2.
Effects of complexing agents in radical copolymerization
Authors: Zubov V. P. , Valuev L. I. , Kabanov V. A. , Kargin V. A. 
Published: April 2003

AbstractRadical copolymerization of methyl methacrylate (MMA, M1) with various monomers has been studied in presence of modifiers, i.e., complexing agents (CA): ZnCl2, AlCl3, AlBr3, Al(C2H5)2Cl, forming coordinate complexes with ester group of the monomer and of the propagating radical. The comonomers of the first group form complexes of similar structure and stability as MMA, methyl acrylate, or butyl acrylate. The comonomers of the second group do not form complexes with the modifiers (vinylidene chloride, 2,6‐dichlorostyrene, p‐chlorostyrene, styrene). For all systems studied the copolymer composition follows the Mayo‐Lewis equation. In the first group of the systems the effective reactivity ratios (r1, r2) approach unity with increase of the CA molar content (r1 = r2 ≃ 1 at [(CA)/MMA] + [MA] ≥ 0,3) In the second group of the systems the values of r1 either increase to a limit value (at [CA]/[MMA] ≥ 0.3), pass through maximum, or decrease to a limiting value with the CA molar content. The values of r2 decrease in all systems. The character of variation of r1 and r2 has been explained in terms of effects of the CA's on reactivity of MMA and PMMA radical. The equations for the copolymer compositions in these systems have been derived.
Cross‐termination rate constants in copolymerizations of some methacrylates and styrene
Authors: Ito Katsukiyo 
Published: April 2003

AbstractCross‐termination rate constants in the copolymerization of some methacrylates with styrene were determined. The rate constants obtained decrease with increasing r1 and increase with decreasing r2. The relationship between the cross‐termination and propagation rate constants was discussed on theoretical and experimental bases.
Optically active copolyamides by melt and solution condensation polymerization
Authors: Yamaguchi Hidemasa , Ueno Hiroshi , Minoura Yuji 
Published: April 2003

AbstractThe melt and solution condensation copolymerization of nylon salts which were prepared from d‐camphoric acid and adipic acid with hexamethylenediamine were carried out, and optically active copolyamides were obtained. The copolyamides obtained had a positive specific rotation. The specific rotations for the copolyamides increased with increasing content of d‐camphoryl units in the copolymers. The optical rotatory dispersion of the copolyamides had positive curves and were found to fit the simple Drude equation. The λc values of the polymers obtained by the melt and solution condensation polymerization were 241 mμ and 245 mμ, respectively.
Optically active copolyamides by interfacial condensation polymerization
Authors: Yamaguchi Hidemasa , Ueno Hiroshi , Minoura Yuji 
Published: April 2003

AbstractThe polymerization of d‐camphoryl dichloride with polymethylenediamines (n = 2, 3, 5, 6, 7, 9) and copolymerization of hexamethylenediamine with d‐camphoryl dichloride and adipyl dichloride were carried out by the interfacial condensation method, and optically active copolyamides were obtained. The specific rotation of poly(hexamethylene camphoramide) obtained increased markedly with increasing intrinsic viscosity over the range of 0.05–0.10. The specific rotation for the copoyamides increased linearly with increasing content of d‐camphoryl units in the polymers. The optical rotatory dispersion of the polyamides and copolyamides had a negative curve which fit the simple Drude equation. The λc values of the polyamides and the copolymers obtained were 265 and 273–285 mμ, respectively. In order to investigate the conformation of the polyamides, the effects of solvent on the specific rotation of the polymers were studied.
γ‐Ray‐induced polymerization of α‐haloacrylic acids
Authors: Watanabe Haruhiko , Murano Masao 
Published: April 2003

AbstractThe γ‐ray induced polymerizations of α‐chloroacrylic acid, mp 66°C, and α‐bromo‐acrylic acid, mp 72°C, were investigated in the temperature range from 35°C to 85°C. An analysis of polymerization kinetics was made, and results were similar to those reported in the literature for other vinyl monomers. On heating of the polymer obtained, elimination of hydrogen halide takes place, and intramolecular lactone formation is observed. The rate of lactone formation of poly(α‐chloroacrylic acid) obtained in the solid‐state polymerization was found to be higher than that in the liquid state, because a highly isotactic configuration of polymers, tends to be formed in the solid‐state polymerization, and elimination of hydrogen chloride is facilitated with an isotactic 52 helix structure.
Thermal degradation of poly(alkyl acrylates). I. Preliminary investigations
Authors: Grassie N. , Speakman J. G. 
Published: April 2003

AbstractA qualitative survey of the thermal degradation reactions which occur in poly(ethyl acrylate), poly(n‐propyl acrylate), poly(isopropyl acrylate), poly(n‐butyl acrylate) and poly(2‐ethylhexyl acrylate) has been made by using three thermal analytical methods: thermogravimetric analysis (TGA), thermal volatilization analysis (TVA), and the dynamic molecular still (DMS), all combined with infrared and mass spectrometry. Degradation in poly(isopropyl acrylate), which is a secondary ester, becomes discernible at 260°C and proceeds in two stages. The other four polymers, which are all primary esters, are more stable. They degrade in a single‐stage process starting at 300°C. The principal volatile products from the primary esters are carbon dioxide and the olefin and alcohol corresponding to the alkyl group. A roughly equivalent quantity of short‐chain fragments is also formed. From poly(isopropyl acrylate), carbon dioxide and propylene are the only volatile products in the first phase of the reaction.
Modification of poly(vinyl alcohol) through reaction with phosphorus‐containing reactants
Authors: Carraher Charles E. , Torre Larry 
Published: April 2003

AbstractCrosslinked products of the form:
magnified image
and
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have been formed from the interfacial condensation of phosphorus diacid halides with poly(vinyl alcohol). Product yield and amounts of phosphorus reactant included in the product increases as the amount of base increases. Product stability in aqueous systems decreases in the order neutral > base > acid.
Stereospecific polymerization of isobutyl vinyl ether. III. Polymerization with VCl3 • LiCl
Authors: Joh Yasushi , Harada Koichi , Yuki Heimei , Murahashi Shunsuke 
Published: April 2003

AbstractThe polymerization of isobutyl vinyl ether by vanadium trichloride in n‐heptane was studied. VCl3 • LiCl was prepared by the reduction of VCl4 with stoichiometric amounts of BuLi. This type of catalyst induces stereospecific polymerization of isobutyl vinyl ether without the action of trialkyl aluminum to an isotactic polymer when a rise in temperature during the polymerization was depressed by cooling. It is suggested that the cause of the stereospecific polymerization might be due to the catalyst structure in which LiCl coexists with VCl3, namely, VCl3 • LiCl or VCl2 • 2LiCl as a solid solution in the crystalline lattice, since VCl3 prepared by thermal decomposition of VCl4 and a commercial VCl3 did not produce the crystalline polymer and soluble catalysts such as VCl4 in heptane and VCl3 • LiCl in ether solution did not yield the stereospecific polymer. It was found that some additives, such as tetrahydrofuran or ethylene glycol diphenyl ether, to the catalyst increased the stereospecific polymerization activity of the catalysts. Influence of the polymerization conditions such as temperature, time, monomer and catalyst concentrations, and the kind of solvent on the formed polymer was also examined.
Polyimides based on pyrazinetetracarboxylic dianhydride and some related model compounds
Authors: Vaughan George B. , Rose Jerry C. , Brown G. P. 
Published: April 2003

AbstractA study was made of polyimides based on pyrazinetetracarboxylic dianhydride (PTDA) plus heterocyclic diamines different from the one previously reported by Hirsch. It was postulated that thermal properties might be improved if the diamine portion did not contain the N–N linkage. The results indicate that these heterocyclic‐based polyimides are in fact of lower thermal stability and of less molecular weight buildup than their corresponding polypyromellitimides. Thermal failure, outlined by their TGA curves, is shown not to be due to an inherent lack of stability for such polymers, but rather, to synthesis problems arising from both the anhydride and amine precursors. The synthetic problems are twofold: (1) the heterocyclic diamines used in this study display low reactivity; (2) pyrazinecarboxylic acids readily decarboxylate. These conclusions were drawn from a correlation of the relative basicity values of the diamines of consideration and from study of a series of model compounds prepared from an appropriate amine or diamine with PDTA, pyrazinedicarboxylic anhydride, phthalic anhydride, or pyromellitic dianhydride. An accumulation of infrared and mass spectra data for these models relate that the proposed pyrazine polyimides are not of complete polyimide structure, but rather resemble recurring amide‐imide units.
Kinetics of vinyl acetate emulsion polymerization
Authors: Harriott Peter 
Published: April 2003

AbstractThe emulsion polymerization of vinyl acetate has generally been considered a special type of reaction that is not covered by the Smith‐Ewart theory. Although the number of particles depends on coalescence rates and can not be predicted by this theory, the polymerization rate data are consistent with the general concepts of Smith and Ewart, including reaction primarily inside swollen polymer particles, escape of radicals from particles, and termination of chains inside the particles. Allowing for rapid exchange of radicals following chain transfer leads to a simple equation which fits much of the published data for cases of both very low and very high values of n, the average number of radicals per particle.
Polymerization of acrylonitrile with VCl4–Al(C2H5)3 catalyst system in presence of acetonitrile
Authors: Dixit Sunit S. , Deshpande A. B. , Kapur S. L. 
Published: April 2003

AbstractThe polymerization of acrylonitrile with the homogeneous catalyst system of VCl4–AlEt3 in acetonitrile at 40°C has been investigated. The rate of polymerization is found to be first‐order with respect to monomer and inversely proportional to the catalyst concentration. The overall activation energy for this catalyst system is 10.97 kcal/mole. The inverse proportionality of rate of polymerization with the catalyst concentration is attributed to the permanent complex formation between the catalyst complex and acrylonitrile, and a reaction scheme is proposed.
Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings
Authors: Taimr Ludek , Smith James G. 
Published: April 2003

AbstractPolyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings are prepared from 1,4‐bis(carboethoxy)bicyclo[2.2.2]octane, 1,4‐bis(hydroxymethyl)bicyclo[2.2.2]‐octane and the 1,5‐disubstituted bicyclo[3.2.2]nonane analogs. These polyesters are compared to the related polymers containing 1,4‐phenylene and trans‐1,4‐cyclohexylene rings in terms of their melting point, thermal stabilities and oxidative stabilities. The lower symmetry of the bicyclo[3.2.2]nonane ring produces lower‐melting polymers than the other ring systems. The remaining three rings are approximately equivalent in their effect on the melting point of a polymer provided that no more than one bicyclo[2.2.2]octane ring is present per polymer repeat unit. Two such rings produce a highermelting polymer than any other combination. Both the thermal and oxidative stabilities of the polyesters is improved by the presence of the bicyclo rings. This is attributed to the rings providing an approximation of a ladder polymer.