bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation‐induced polymerization of glass‐forming systems. V. Initial polymerization rate in binary glass‐forming systems
Authors: Kaetsu Isao , Okubo Hiroshi , Ito Akihiko , Hayashi Koichiro 
Published: April 2003

AbstractThe radiation‐induced polymerization of binary systems consisting of glass‐forming monomer and glass‐forming solvent in supercooled phase was studied. The initial polymerization rates were markedly affected by Tg (glass transition temperature) and Tv of the system (30–50°C higher than Tg), which turned to be functions of the composition. The composition and temperature dependence of initial polymerization rate in binary glass‐forming systems were much affected by homogeneity of the polymerization system and the Tg of the glass‐forming solvent. The composition and temperature dependences in the glycidyl methacrylate–triacetin system as a typical homogeneous polymerization system were studied in detail, and the polymerizations of hydroxyethyl methacrylate–triacetin and hydroxyethyl methacrylate–isoamyl acetate systems were studied for the heterogeneous polymerization systems; the former illustrates the combination of lower Tg monomer and higher Tg solvent and the latter typifies a system consisting of higher Tg monomer and lower Tg solvent. All experimental results for the composition and temperature dependence of initial polymerization rate in binary glass‐forming systems could be explained by considering the product of the effect of the physical effect relating to Tv and Tg of the system and the effect of composition in normal solution polymerization at higher temperature, which was also the product of a dilution effect and a chemical or physical acceleration effect.
Synthesis of poly‐α,α‐diphenylglycine. II. Cationic polymerization of 4,4‐diphenyl‐Δ2‐1,2,3‐triazolin‐5‐one
Authors: Ikeda K. , Smets G. , L'abbé G. 
Published: April 2003

Abstract4,4‐Diphenyl‐Δ2‐1,2,3‐triazolin‐5‐one (I) was found to undergo a cationic polymerization under the influence of boron trifluoride etherate in an anhydrous solvent. The poly‐α,α‐diphenylglycine (III) thus formed contained a larger amount of oligomers than the polymer obtained by thermal decomposition as described in the preceding paper. The molecular weight distribution was further shown to depend on the monomer and catalyst concentration and on the nature of the solvent. A mechanistic rationalization is proposed, involving propagating triazolinium ion pairs (VII) which are not interrupted by chain transfer or termination in the absence of water or alcohol. In the presence of water or alcohol, no polymerization occurred, but the normal acid‐catalyzed decomposition products (IV and V) were then obtained. 1‐Methyl‐4,4‐diphenyl‐Δ2‐1,2,3‐triazolin‐5‐one (VIII) was also treated with BF3 · OEt2 in a dry solvent at room temperature and furnished 1‐methyl‐3‐phenyl‐indolin‐2‐one (XII) instead of a polyamide. This reaction constitutes a new method for the synthesis of these heterocycles.
Organometallic polymers. XXIV. Radical‐initiated copolymerization of ferrocenylmethyl acrylate and methacrylate with acrylonitrile, maleic anhydride, and N‐vinyl‐2‐pyrrolidone
Authors: Ayers O. E. , McManus S. P. , Pittman C. U. 
Published: April 2003

AbstractFerrocenylmethyl acrylate (I) and ferrocenylmethyl methacrylate (II) have been readily copolymerized with maleic anhydride in benzene–ethyl acetate solutions. Similarly, II has been copolymerized with both acrylonitrile and N‐vinyl‐2‐pyrrolidone in benzene solutions to give higher molecular weight copolymers in high yields. In all cases azobisisobutyronitrile has been the initiator. Based on e values obtained, the metal carbonyl substituent acts as an electron‐withdrawing group. Over a wide range of comonomers (N‐vinyl‐2‐pyrrolidone, styrene, vinyl acetate, methyl acrylate, acrylonitrile, and maleic anhydride) I and II exhibit r1 values lower than (and r2 values higher than) similar copolymerizations with methyl acrylate or methyl methacrylate. Further more, the Q values found for I (0.03–0.11) and II (0.08–0.18) are smaller than those for methyl acrylate (0.46) and methyl methacrylate (0.74). Thus, I and II are less reactive than expected, presumably due to steric effects.
Effects of structure and composition on the titration curves of some synthetic copolymers in nonaqueous media
Authors: Chatterjee S. K. , Gupta Nandita Datta 
Published: April 2003

Abstractp‐Aminobenzoic acid, p‐hydroxybenzoic acid, and formaldehyde were condensed in various molar proportions in the presence of acid catalyst to obtain copolymers of various compositions. Conductometric and potentiometric titrations were carried out on seven copolymers having different feed compositions in nonaqueous solvents with acid as well as base. The titration curves indicated a large number of additional breaks inflections before the complete neutralization of COOH, OH, or NH2 groups. These observations have been interpreted in terms of degree of polymerization, composition, and structure of the copolymers.
Complexed copolymerization of vinyl compounds with alkylaluminum halides
Authors: Hirooka Masaaki , Yabuuchi Hiroshi , Kawasumi Shohachi , Nakaguchi Kohei 
Published: April 2003

AbstractThe monomer reactivity in the complexed copolymerization of vinyl compounds with alkylaluminum halides has been extensively surveyed. Equimolar copolymers were obtained in various combinations of monomers which are classified into two monomer groups, A and B. The group B monomers are conjugated vinyl compounds having nitrile or carbonyl groups in the conjugated position and form complexes with alkylaluminum halides. The group A monomers are donor monomers having low values, such as olefins, haloolefins, dienes, and unsaturated esters. These A monomers belong to the same group of monomers which give alternating copolymers in conventional radical copolymerization with maleic anhydride, SO2, and so on. In addition the complexed copolymerization has the same specific characteristics as the conventional alternating copolymerization, i.e., high reactivities of allyl‐resonance monomers and inner olefins and no transfer of halogen atom to the copolymers in CCl4. These features suggest little or no participation of the A monomer radical. The Q‐e scheme is also discussed in terms of the monomer reactivity. More than two monomers selected from groups A and B give multicomponent copolymers in which alternating sequential structures hold with respect to A and B. Anomalous mutual reactivities between two B monomers in the terpolymerization were observed and indicate that the nature of radical in the complexed copolymerization may be different from that expected by the Lewis‐Mayo equation. The complexed radical mechanism previously proposed is discussed in connection with the specific behavior mentioned above.
Allyl stearate copolymers and terpolymers: Thermal, mechanical, and solution properties of polymers incorporating vinyl chloride
Authors: Jordan Edmund F. , Riser George R. , Artymyshyn Bohdan , Smith Stephen , Wrigley A. N. 
Published: April 2003

AbstractPoly(allyl stearate) and selected copolymers and terpolymers modified by allyl stearate were investigated in this work. The systems selected and studied over a wide range of composition, included copolymers with vinyl stearate and with vinyl chloride, and terpolymers containing vinyl chloride and allyl stearate, modified further by vinyl stearate or vinyl acetate. Copolymers of allyl stearate and vinyl stearate were studied incrementally across the range of composition. In the ester copolymers the effect of degradative chain transfer on crystallization and solution properties was studied. A relation was obtained between intrinsic viscosities and number‐average molecular weights; a shift in molecular weight distribution with increase in allyl component was demonstrated. The crystallinity contributed by the side chains was shown to be characterized by isomorphic replacement regardless of molecular weight. Mechanical properties of internally plasticized copolymers of allyl stearate and vinyl chloride, in a limited composition range, were compared with corresponding data for copolymers of vinyl stearate and vinyl chloride. While molecular weight reduction of the allylic copolymers exceeded that for the vinyl ester system, the effect, in the useful plasticization composition range, was not enough to grossly affect ultimate properties. The glass transitions of the hypothetical amorphous homopolymers of both fatty esters were estimated to be the same. Because this Tg was low (ca. −110°C), only relatively small mole fractions of allyl stearate were needed for effective plasticization. Isochronal temperature–composition diagrams also showed both systems to be essentially identical, but marked differences were found for diluent mixtures incorporating di‐2‐ethylhexyl phthalate (DOP). An empirical equation, previously derived, adequately predicted the decline in degree of polymerization with increase in allyl stearate between the limits of the respective homopolymers for all copolymers studied. Terpolymers followed the trends of the copolymers and offered no special property advantage.
Studies on the nature of multiple glass transitions in low acrylonitrile, butadiene–acrylonitrile rubbers
Authors: Ambler M. R. 
Published: April 2003

AbstractA study of the occurrence of multiple glass transitions in acrylonitrile–butadiene rubbers (NBR) has been made. Copolymerization theory was used to predict the change in comonomer composition with conversion for comonomer ratios both above and below the calculated azeotropic composition of 64% butadiene/36% acrylonitrile by weight. The results of these calculations suggested that multiple glass transitions, which occur only in NBR of less than 36% acrylonitrile, were due to an incompatibility of copolymer species of divergent comonomer compositions. This was shown by differential thermal analysis to be the case for various experimental polymers of known comonomer composition. A series of NBR's was prepared by incremental addition of acrylonitrile monomer during polymerization, and the resultant glass transition temperatures were evaluated. Results obtained showed that experimental samples which had single glass transitions also had a much narrower spread of comonomer species than the corresponding rubber polymerized with the use of full initial charge of both monomers. The data indicate that NBR's having a single glass transition, regardless of acrylonitrile content, may be prepared by incremental addition of acrylonitrile monomer during polymerization. Existing copolymerization theory appears to be adequate for predicting incremental monomer addition schedules suitable for the polymerization of NBR's having a single glass transition.
Friedel‐Crafts crosslinking of polystyrene
Authors: Grassie N. , Gilks J. 
Published: April 2003

AbstractPolystyrene may be crosslinked by p‐dichloromethylbenzene (DCMB) in 1,2‐dichloroethane solution with SnCl4 as catalyst. Combined intra‐ and intermolecular crosslinking can be measured by evolution of hydrogen chloride and by an ultraviolet spectral method, and the results for the two methods are in excellent agreement. Intermolecular crosslinking may be calculated separately from number‐average molecular weight measurements, so that the extent of intramolecular crosslinking may be deduced by difference. Rate equations for the overall, intermolecular, and intramolecular reactions have been obtained as follows:

The anomalous behavior with respect to polystyrene concentration may be due to inhibition of the intramolecular reaction because of increasing interpenetration of polystyrene molecules as the concentration of polystyrene is increased. The rate constant for the intermolecular reaction, which shows “normal” kinetic behavior has been compared with values for the reaction of DCMB with the model compounds benzene, toluene, diphenylmethane, and benzyl chloride. The very much smaller value for polystyrene compared with the models has been accounted for in terms of adverse steric effects when the reaction is occurring in the polymer chain environment.
Redox polymerization of acrylonitrile‐kinetics of the reaction initiated by the redox system dimethyl sulfoxide–Mn(III)
Authors: Devi N. Ganga , Mahadevan V. 
Published: April 2003

AbstractThe kinetics of oxidation of dimethyl sulfoxide by tervalent manganese was investigated in sulfuric and perchloric acid media at 40–45°C. A mechanism involving prior complexation between reactants followed by a reversible electron‐transfer step was shown to be consistent with the kinetics. The radical ion thus produced initiates polymerization of acrylonitrile, the termination being effected by the oxidant. Rates of polymerization vary directly as the sulfoxide concentration and are proportional to the square of the monomer concentration and being independent of the oxidant. Oxidation as well as polymerization is retarded by Mn(II). Average degrees of polymerization lend support to the proposed mechanism. Rate parameters have been evaluated in the two media, and their significance is discussed.
Polymerization of vinyl chloride in the presence of precipitants. I
Authors: Arita Koichiro , Stannett V. 
Published: April 2003

AbstractThe kinetics of bulk and precipitation polymerization of vinyl chloride has been studied over wide range of reaction temperature by using γ‐ray induced initiation. The autoacceleration effect, which has been observed by many investigators in the case of chemically initiated bulk polymerization of vinyl chloride above 40°C and has been the most controversial aspect of the bulk polymerization of vinyl chloride, was found to disappear in the bulk polymerization below 0°C. In the bulk polymerization at 40°C, the autoacceleration effect was observed up to 20%, in agreement with the results of previous investigators, and a pronounced effect of the size of polymer particles on the time–conversion curve was observed. The kinetics of precipitation polymerization of vinyl chloride in the presence of some nonsolvents was successfully described by a oneparameter equation. A kinetic scheme, which clearly explains the zero‐order reaction behavior of bulk polymerization at low temperature and the kinetic behavior of precipitation polymerization described by the empirical equation, is proposed. The autoacceleration effect in the bulk polymerization at 40°C was considered to be essentially the same phenomenon as the small retardation period observed in the bulk polymerization at low temperature.
α‐Substituted diisopropylbenzene hydroperoxides for low‐temperature SBR polymerization
Authors: Bennett Bailey , Mueller W. J. , Nathan Richard A. 
Published: April 2003

AbstractFour pure hydroperoxides were evaluated as initiators for the polymerization of styrene–butadiene rubber (SBR) at 5°C. These materials were the meta and para isomers of mono‐ and dihydroperoxy‐diisopropylbenzene. Results showed that the monohydroperoxides produced somewhat faster reactions than a control hydroperoxide, p‐menthane hydroperoxide. Response to mercaptan level adjustments was good, providing polymer with a Mooney viscosity in the 50 to 60 range. The reaction rate with the dihydroperoxides was slower, but again provided polymer with a satisfactory viscosity. Basic physical property measurements on polymers prepared with the pure hydroperoxides or control hydroperoxides showed only minor differences. It is anticipated that these differences can be eliminated by small adjustments in the compound recipe.
Méthodes chimiques d'analyse des polyacroléines linéaires
Authors: Thivollet Pierre , Golé Jean 
Published: April 2003

AbstractLinear polyacroleins prepared by anionic polymerization give the structural repeat units of the types \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--}[{\rm CH}\left( {{\rm CHO}} \right)\hbox{--} {\rm CH}_{\rm 2} {\rm \rlap{--} ], \rlap{--} [CH}_{\rm 2} \hbox{--} {\rm CH}\left( {{\rm CHO}} \right)\rlap{--} ], $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH}\left( {{\rm CH}\hbox {\rm CH}_2 } \right)\hbox{\rm O\rlap{--} ]} $\end{document} without any cyclization. Analysis of these polymers by several methods reveal the nature and amount of each structural species, and an estimation of their distribution along the polymeric chain.
Intrinsic viscosity of solutions of rigid particles at high shear rates
Authors: Layec Yves , Wolff Claude 
Published: April 2003

AbstractThe results of a numerical calculation which extends Scheraga's calculation on the non‐Newtonian behavior of the viscosity factor v of rigid ellipsoid solutions are given here and compared to experimental data obtained on different poly(γ‐benzyl L‐glutamate) samples in helical configuration, over a wide range of molecular weight, up to 980,000. Relations for the axial ratio p, the rotary diffusion constant D, and a test of the deformability of the polymer under shear, are given as functions of the shear‐rate dependence of the intrinsic viscosity. The experimental behavior under shear shows that PBLG becomes somewhat flexible in dichloroethane, but not in m‐cresol. The dimensions calculated from the viscometric results suggest discrete changes in the length per monomeric unit of the helix at different well defined molecular weights.
Thermal decomposition of 4,4′‐isopropylidene bis‐2,6‐dibromophenol (tetrabromobisphenol‐A)
Authors: Factor A. 
Published: April 2003

AbstractThe thermal decomposition of tetrabromobisphenol‐A (TBBPA) was found to proceed via an autocatalytic free‐radical process. The major products of the decomposition are HBr; mono‐, di‐ and tribromobisphenol‐A; phenol; mono‐, di‐, and tribromophenol; and eventually, char. It was generally found that o‐ and p‐halophenols are thermally unstable. In contrast, the m‐bromophenol, 3,5‐dibromo‐2,4,6‐trimethylphenol (dibromomesitol) was found to be quite stable. In addition, o‐ and p‐halo‐substituted phenols were found to react with LiI at 250°C to produce I2, while m‐halophenols did not. These results are explained by the formation from o‐ and p‐halo‐substituted phenols of a reactive halocyclohexadienone.
Thermally stable polymers derived from 2,3,5,6‐tetraaminopyridine
Authors: Gerber Arthur H. 
Published: April 2003

AbstractThe stable trihydrochloride salt of 2,3,5,6‐tetraaminopyridine (TAP) has been found to be a versatile intermediate to a variety of thermally stable polymers such as polybenzimidazoles (PBI), polyimidazopyrrolones (pyrrones), and polybenzimidazobenzophenanthroline (BB polymer). The controlled reactivity of two of the four amino sites of TAP · 3HCl towards diacid halides and dianhydrides makes possible the preparation of high molecular weight, soluble polyamide prepolymers at mild temperatures. PBI, pyrrones, and BB polymer are obtained from the linear polyamide precursors by heating at 150–375°C. Unoptimized cyclized polymers were aged isothermally in air at 600°F (316°C) and found to be superior to analogous polymers described in the literature. Weight retentions of up to 97% were observed after 500 hr in air at 600°F.
Prediction of molecular weight distributions in branched polymers
Authors: Jackson R. A. , Small P. A. , Whiteley K. S. 
Published: April 2003

AbstractA theoretical treatment of long branching in radical polymerization in a continuous stirred tank reactor is presented. The treatment takes into account radical termination by disproportionation and/or combination, transfer to polymer and/or additive of low molecular weight, residence time, and injection of polymer. In the absence of added polymer, the molecular weight distribution depends upon four parameters which can be expressed as P̄n and ratios of the rate of polymerization to the rate at which radicals (a) leave the reactor, (b) combine, and (c) transfer to polymer. The kinetic equations were converted into a differential equation which was solved numerically to give polymer and radical moments. An analytical solution is presented for the case where combination is absent. P̄w/P̄n is predicted to increase smoothly in a markedly exponential manner with increasing polymer transfer, combination, P̄n, and mean residence time. At no stage do any of the moments become infinite unless the residence time is infinite. For polymers of wide distribution, the second and higher radical moments can exceed the corresponding polymer moments so that most of the large molecules leave the reactor as radicals. Beasley's and Nicolas's treatments are shown to be limiting cases at low polymer transfer.
Alternating cooligomerization of isoprene and propylene with vanadium catalyst
Authors: Furukawa Junji , Tsuruki Shigenori , Kiji Jitsuo 
Published: April 2003

AbstractAlternating cooligomerization of isoprene with propylene has been investigated between −30 and 0°C, VO(acac)2–Et3Al–Et2AlCl being used as catalyst. In the presence of an excess of propylene, 2,4,7‐trimethyl‐1,4‐octadiene and 2,4‐dimethyl‐1,4‐nonadiene are selectively formed. The formation is explained by the alternating coordination of isoprene and propylene to the vanadium. When triphenylphosphine or pyridine is added to the catalyst, the cooligomerization is suppressed while the formation of the dimer and trimer of isoprene is high.
Copolymerization of styrene and diethyl fumarate with zinc bromide. V. Electroinitiated copolymerization at high current strengths
Authors: Phillips D. Colin , Smith J. D. B. , Davies David H. 
Published: April 2003

AbstractThe electroinitiated copolymerization of styrene and diethyl fumarate in methanol solvent with zinc bromide as electrolyte has been investigated at high current strengths (200–500 mA). Unlike the copolymerization behavior observed at lower current strengths (< 200 mA), it is found that the cathodically produced copolymers deviate from a 1:1 composition and show a significant deficiency in styrene. The copolymer products can be separated into two well‐defined fractions: a toluene‐soluble fraction (normal copolymer) and a toluene‐insoluble one (styrene‐deficient copolymer). These deviations in copolymer composition from a 1:1 monomer ratio are attributed to the occurrence of cathodically induced electroreductive hydrolysis side reactions with diethyl fumarate leading to the formation of carboxylate or acid salt species. Reaction of these hydrolyzed species with diethyl fumarate results in the formation of fumarate‐rich copolymers.
Interaction of polyvinylpyrrolidone with methyl orange and its homologs in aqueous solution: Thermodynamics of the binding equilibria and their temperature dependences
Authors: Takagishi Toru , Kuroki Nobuhiko 
Published: April 2003

AbstractThe interaction of polyvinylpyrrolidone with methyl orange, ethyl orange, propyl orange, and butyl orange has been studied by an equilibrium dialysis method at 5, 15, 25, and 35°C. The first binding constants and the thermodynamic parameters in the course of the binding have been calculated. It was found that the free energy and the enthalpy changes are all negative and the entropy change is largely positive. The longer the alkyl chain of the dyes, the more positive is the enthalpy change (though it is always in the negative direction) and hence the larger is the entropy change. The favorable free energy of the binding of butyl orange observed for the formation of the dye–polymer complex seems to be a result of a favorable entropy change rather than any favorable enthalpy change. Temperature dependences of the thermodynamic functions were apparently observed. That is, ΔF and ΔH become larger in absolute magnitude as the temperature increases. The positive quantity of ΔS tends to decrease with increasing temperture. All these facts obtained can be interpreted satisfactorily by the hydrophobic interaction between hydrocarbon portions of the dyes and nonpolar parts of the macromolecule.