bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular weight distribution of poly‐N‐vinylcarbazole obtained in catalytic solid‐state polymerization
Authors: Higashimura T. , Matsuda T. , Okamura S.
Published: April 2003

The molecular weight distribution of poly‐N‐vinylcarbazole (PVCar) obtained in solid‐state polymerization with various catalysts or γ‐rays was measured by gel‐permeation chromatography, in order to determine the mechanism of the solid‐state polymerization. In addition, the molecular weight distribution of PVCar obtained in the solution polymerization by the cationic catalyst was also measured. The molecular weight distribution of PVCar obtained in the catalytic solid‐state polymerization was broad and had three peaks, independent of the nature of catalysts, radical and cationic. A large amount of low molecular weight oligomer (probably dimer or trimer) was formed in the catalytic solid‐state polymerization of VCar. The molecular weight distribution of PVCar obtained in the cationic solution polymerization showed only one sharp peak. On the other hand, the molecular weight of PVCar obtained in the radiation‐induced solid‐state polymerization was larger than that obtained in the catalytic solid‐state polymerization, and dimer or trimer was not formed. The molecular weight distribution of PVCar obtained was composed of one sharp peak in the high molecular weight region, and a broad peak in the low molecular weight region, and was extremely different from that of PVCar obtained in the catalytic solid‐state polymerization.
Polymerization and reaction of tetraoxane with various olefins catalyzed by BF3O·(C2H5)2
Authors: Miki T. , Higashimura T. , Okamura S.
Published: April 2003

The copolymerization of tetraoxane with various olefins by BF3·O(C2H5)2 in ethylene dichloride at 30°C has been studied. The gas chromatographic technique was employed for the determination of concentration of each compound. The rate of tetraoxane consumption was decreased by the addition of olefins in the order of; no addition > trans‐stilbene > styrene > 1,1‐diphenylethylene > 2‐chloroethyl vinyl ether > cyclohexene ≥ indene ≥ α‐methylstyrene. The formation of the methanol‐insoluble copolymer of tetraoxane and olefin was not confirmed. However, 4‐methyl‐4‐phenyl‐1,3‐dioxane and 4,4‐diphenyl‐1,3‐dioxane were formed in the reaction of tetraoxane with α‐methylstyrene and 1,1‐diphenylethylene, respectively. 4,4‐Diphenyl‐1,3‐dioxane was identified on the basis of the molecular weight measurement, elemental analysis and NMR and infrared spectroscopy. On the other hand, 1,3‐dioxane derivatives were not formed in the reaction of tetraoxane with α,β‐disubstituted olefins. Monomer composition dependence of the copolymerization of tetraoxane with 1,1‐diphenylethylene or α‐methylstyrene has been studied. The amount of 4,4‐diphenyl‐1,3‐dioxane formed reached a maximum at a monomer composition of 1:1 in the reaction of tetraoxane with 1,1‐diphenylethylene. The formation of cyclic dimer of α‐methylstyrene was suppressed by tetraoxane.
Properties of nylon 6 anionically obtained with NaAl(Lac)4 catalyst and polymerization of ϵ‐caprolactam with NaAl(Lac)3(OEt) catalyst
Authors: Konomi T. , Tani H.
Published: April 2003

The m‐cresol‐insoluble polymer of ϵ‐caprolactam obtained with NaAl(Lac)4 catalyst is converted to a soluble polymer on treatment with dilute (0.1 wt‐%) aqueous hydrochloric acid without any accompanying degradation of polymer chain. Aluminum contained in the polymer was not removed completely by extensive extraction with methanol, regardless of the solubilities of the polymers. This fact suggests the existence of two forms of aluminum in the polymer: one contributes to insolubility of the polymer and the other does not. The polymerization behavior in the case of NaAl(Lac)3(OEt) was somewhat different from that of NaAl(Lac)4 and of NaAl(Lac)3(NHBu). These results are considered to reflect a difference in the stability of the Al‐O, Al‐(Lac), and Al‐N bonds in the catalyst.
Synthesis and characterization of polyiminobenzothiazoles
Authors: Evers Robert C.
Published: April 2003

A series of polyiminobenzothiazoles was synthesized by the polymerization of either 2,6‐dichloro‐ or 2,6‐diphenoxybenzobisthiazole with a number of aromatic diamines. A polymer was also obtained from the self‐condensation of either 2‐chloro‐ or 2‐phenoxy‐6‐aminobenzothiazole. The polymers were characterized by their elemental analysis and infrared spectra. Thermogravimetric analysis, differential thermal analysis, and softening under load were used to evaluate their thermal properties. The polymers were found to be light tan to brown powders which showed only slight softening below their decomposition temperatures. Onset of breakdown under thermogravimetric analysis in a nitrogen atmosphere generally occurred at 375–400°C. The polymers were sparingly soluble in organic solvents and had inherent viscosities in the range of 0.11–0.55.
Thermal degradation of nadic methyl anhydride‐cured epoxy novolac
Authors: Gac N. A. , Spokes G. N. , Benson S. W.
Published: April 2003

A DEN 438 epoxy novolac–Nadic methyl anhydride‐cured polymer was pyrolyzed in vacuum at temperatures to 800°C. Detailed analyses of the products have yielded information on the mechanism of decomposition. Two thirds of the weight loss of the polymer results in formation of relatively involatile high molecular weight gases. Carbon dioxide evolution indicates that at least 50% of the initial anhydride forms diester groups. The degradation of diester sites yields methylcyclopentadiene that is almost entirely decomposed to carbonaceous char.
Polyamide‐imides
Authors: Terney S. , Keating J. , Zielinski J. , Hakala J. , Sheffer H.
Published: April 2003

A novel preparation of polyamide‐imides from diphenylmethane diisocyanate and trimellitic anhydride in N‐methylpyrrolidone is described. Partial substitution of trimellitic anhydride with either maleopimaric acid, terephthalic acid, or by various di‐anhydrides permitted a correlation of structure with solution stability and thermal properties. Heat resistance improved with increasing imide content of the polyamide‐imide. Almost all solutions advanced in viscosity on storage at room temperature. The least stable solutions were those that deviated the most from 50–50 amide‐imide. However, the viscosity changes depended somewhat on the type of modifying ingredient. For example, polyamide‐imides modified by substitution of 10% PMDA (pyromellitic anhydride) or BPDA (benzophenone tetracarboxylic acid dianhydride) were less stable than those modified with 10% (cyclopentanetetracarboxylic acid dianhydride) CPDA or THFDA (tetrahydrofuran‐2,3,4,5‐tetracarboxylic acid dianhydride). The use of excess reagent and of monofunctional chain stopper was investigated as a means of controlling solution stability.
Cationic polymerization of β‐pinene, styrene and α‐methylstyrene
Authors: Pietila Heikki , Sivola Arto , Sheffer Howard
Published: April 2003

Molecular weight distributions determined by gel permeation chromatography demonstrate that α‐methylstyrene copolymerizes with both β‐pinene and styrene, forming both bi‐ and terpolymers. The composition of precipitated polymer versus crude polymer, as determined by nuclear magnetic resonance, suggests that β‐pinene and styrene also copolymerize. Extraction of the latter bipolymer of β‐pinene and styrene with acetone gives only a small amount of insoluble β‐pinene homopolymer, confirming that β‐pinene and styrene copolymerize in m‐xylene. GPC analysis shows that each copolymer contains some homopolymer. A comparison of Mn with molecular weight calculated from NMR analysis, assuming chain transfer to solvent, indicates that chain transfer is the predominant method of forming dead polymer. The carbonium ions of the growing chain tend to transfer to solvent with increasing ease in the order β‐pinene, styrene, and α‐methylstyrene.
Preparation of block copolymers by use of peroxide‐terminated prepolymer
Authors: Érdy N. Z. , Ferraro C. F. , Tobolsky A. V.
Published: April 2003

Block copolymers containing poly(tetramethylene oxide) and poly(methyl methacrylate) segments were prepared. A commercially available poly(tetramethylene oxide) terminated with tolylene diisocyanate was capped with tert‐butyl hydroxymethyl peroxide and the resulting prepolymer peroxide was used as a free‐radical initiator of vinyl polymerization. Block copolymers formed in temperature‐programmed vinyl polymerizations possessed improved impact strengths over poly(methyl methacrylate) from 0.35 to 1.18 for a fixed (nonoptimized) block length of poly(tetramethylene oxide).
Some consideration of excluded volume effects in dilute polymer solutions
Authors: Yeh R. , Isihara A.
Published: April 2003

A two‐parameter model is proposed to analyze the viscosity of dilute polymer solutions; and critical comments are given on recent articles by Berry and by Norisuye et al. The data seem to follow our theoretical model better than other models. Light‐scattering data are also analyzed. The data indicate that the distribution function of monomers decays as a simple exponential function for large r.
Thermally stable silarylene‐1,3,4‐oxadiazole polymers
Authors: Kovacs Hanna Nagy , Delman Alvin D. , Simms Bernard B.
Published: April 2003

The effects of incorporating a p‐phenylene‐ (or m‐phenylene)‐1,3,4‐oxadiazole fragment into the backbone of poly[1,4‐phenylene(diphenylsilyl)‐1,4‐phenylene‐2,5‐(1,3,4‐oxadiazole)], which was developed by the authors, was investigated. Bis[(p‐carbohydrazidophenyl)]diphenylsilane was copolymerized with dipentachlorophenyl terephthalate or isophthalate to produce the prepolymers poly[N‐(p‐diphenylsilylbenzoyl)‐N′N″‐(terephthaloyl)‐N″′‐(p‐benzoyl)dihydrazide] and poly[N‐(p‐diphenylsilylbenzoyl)‐N′,‐N″‐(isophthaloyl)‐N″′‐p‐(benzoyl) dihydrazide], respectively. The polyhydrazides were converted by thermal dehydration into poly[1,4‐phenylene(diphenylsilyl)‐1,4‐phenylene‐(1,3,4‐oxadiazole‐2,5‐diyl)‐1,4‐phenylene‐2,5‐(1,3,4‐oxadiazole)] and poly[1,4‐phenyl‐ene(diphenylsilyl)‐1,4‐phenylene‐(1,3,4‐oxadiazole‐2,5‐diyl)‐1,3,4‐(oxadiazole)]. The new polymers were soluble in organic solvents. Films cast from these solutions exhibited good adhesion to glass and metal surfaces. Thermal analysis showed that the heat stability of all these polymers was about the same and that they were resistant to decomposition when heated in air to about 400°C. The results also indicated that these polymers were somewhat less heat‐resistant than samples of poly‐[1,4‐phenylene(diphenylsilyl)‐1,4‐phenylene‐2,5‐]1,3,4‐(oxadiazole) synthesized from bis(p‐carbohydrazidophenyl)diphenylsilane and bis‐(p‐carbopentachlorophenoxy‐phenyl)diphenylsilane.
Polymerization by transition metal derivatives. XII. Factors controlling activity and stereospecificity in the 1,4 polymerization of butadiene by monometallic nickel catalysts
Authors: Durand J. P. , Dawans F. , Teyssie Ph.
Published: April 2003

In the course of investigations of polymerization of diolefins by transition metal derivatives, we have synthesized various monometallic nickel coordination catalysts. The complexes were prepared by reacting 2,6,10‐dodecatriene‐1,12‐diyl nickel with protonic acids; they were shown to initiate the stereospecific polymerization of 1,3‐butadiene. The study of these catalysts showed the strong influence of the nature of the counteranion used on the stereospecificity and the polymerization rate. Moreover, by adding various ligands, we were able to modify the behavior of the catalytic systems and to prepare either pure cis‐1,4 or pure trans‐1,4 or cis–trans equibinary polybutadienes, starting from the same complex and keeping a high 1,4 specificity. Some of these modifications were shown to be reversible.
Polytriazolines
Authors: Hergenrother P. M. , Carlson L. A.
Published: April 2003

Soluble polytriazolines of relatively high molecular weight (ηinh ∼ 0.6 dl/g) have been prepared by the solution polymerization of 2,6‐pyridinediyl dihydrazidine with three different aromatic dialdehydes. Thermogravimetric analysis of the polytriazolines showed weight losses in air and in nitrogen commencing at 280°C and 400°C, respectively. Several attempts to convert triazoline model compounds to the corresponding 1,2,4‐triazoles and quantitatively to prepare methyl‐substituted triazoline model compounds were unsuccessful.
A uniform site theory of ziegler catalysis
Authors: Buls V. W. , Higgins T. L.
Published: April 2003

Polypropylene produced by the TiCl3–diethylaluminum chloride catalyst system was separated into two kinds of polymers, a minor atactic fraction with little or no steric order and a major fraction with a high degree of steric order. Each fraction had a wide molecular weight distribution. The relative amounts, the molecular weights and the molecular weight distributions of the fractions responded differently to changing reaction conditions. This indicates that the fractions are produced by separate catalysts and by different reaction mechanisms. Polymer/catalyst mole ratios from polymerizations at various conditions showed that a least one‐half of the TiCl3 content of a catalyst may become directly involved in the polymerization process. A theory is developed which states that (1) the (unactivated) stereospecific fraction of the catalyst consists of molecules containing eight TiCl3 units which are separated from each other by AlCl3 in solid solution; (2) two chlorine atoms in this molecule are replaced with alkyl groups in the first step of activation; (3) the molecule contains two active sites, one d‐ and the other l‐orienting; (4) the molecules are crystallized in an open structure which has equally reactive sites uniformly spaced; and (5) the AlCl3 component is not an inherent part of the stereospecific catalytic structure but it contributes to high activity by opening the crystal structure.
Analysis of the nonvolatile oxidation products of polypropylene I. Thermal oxidation
Authors: Adams J. H.
Published: April 2003

The nonvolatile products in thermal‐oxidized polypropylene sheet have been quantitatively identified by infrared analysis and chemical reaction. The molecular weight changes with oxidation have been studied by gel‐permeation chromatography. It was determined that there is a functional group at each end of a chain. A general oxidation mechanism scheme for polypropylene is presented. The discovery of γ‐lactone is an indication of the importance of an intramolecular backbiting process. The overall functional group distribution is found to differ from that found in a polyethylene sheet.
A high‐performance fluorocarbon elastomer
Authors: Barney A. L. , Keller W. J. , van Gulick N. M.
Published: April 2003

Perfluorinated elastomeric copolymers of tetrafluoroethylene and perfluoro(methyl vinyl ether), containing 20–50 mole‐% of the vinyl ether moiety, were prepared in aqueous emulsion free radical initiated polymerization systems. The two monomers show sufficiently similar relative reactivity ratios to permit the preparation of homogeneous copolymers at high monomer conversions. Detailed properies of a 65/35 (molar) copolymer, including outstanding fluid and chemical resistance, to aqueous media and to nearly all organic and inorganic fluids, excellent thermal and oxidative stability, and very low permeability, are given. Efforts to vulcanize the copolymer to achieve good mechanical properties over a wide temperature range were not particularly successful. Through the incorporation of an unspecified cure site monomer, vulcanizates showing to a large degree the desirable properties of the raw copolymer along with good stress‐strain properties and compression set resistance have been obtained.
Précisions apportées au mécanisme de la polymérisation du chlorure de vinyle par le chlorure de tertiobutyle‐magnésium en milieu tétrahydrofurannique. Etude par résonance magnétique nucléaire
Authors: Tho Pham Quang , Taieb Maurice
Published: April 2003

NMR analysis of the low molecular weight poly(vinyl chloride) obtained from polymerizations initiated by t‐BuMgCl in THF solution suggests that all the polymer chains have the structure:
magnified image
Enhanced signal/noise ratio by NMR spectrum accumulation confirms this structure in products of higher molecular weights. Examination of the NMR spectrum of vinyl chloride monomer in THF solution reveals the formation of a monomer–THF complex; it seems that the initiation step of the polymerization is governed by this complexation phenomenon.
Synthetic thermally reversible gel systems. IV
Authors: Haas Howard C. , Macdonald Ruby L. , Schuler Alan N.
Published: April 2003

The polymerization kinetics in water of acrylylglycinamide (AG) initiated by K2S2O8 was studied over the temperature range 40.0 to 60.0°C. Monomer concentration was varied from 7.8 × 10−3 to 31.2 × 10−3M and catalyst from 1.85 × to 11.10 × 10−5M. The rate expression is −d[M]/dt = Rp, = k1.22[K2S2O8]0.5[M]1.22, and the overall empirical rate constant, k1.22 = 1.14 × 1011e−15,800/RT 1.0.72 mole−0.72 min−1. To explain the dependence on monomer, a kinetic scheme which includes a bimolecular reaction (k2) between monomer and initiator is suggested. The simplified expression which describes the initial rate of polymerization is: −d[M]/dt = Rp, = k4(2[I]/k5)1/2[M](k1 + k2[M])1/2, where k1, k2, k4 and k5 are rate constants for S2O8 = decomposition, a bimolecular reaction between monomer and initiator, propagation, and termination, respectively. Individual bimolecular rate constants are expressed in liter/mole‐min. The equation predicts a dependence on monomer concentration between 1.0 and 1.5 with 1.5 being approached a t high monomer concentrations. Plots of RP2/[M]2 versus [M] are linear, as predicted by the postulated reaction route and values for k2 and k4/k51/2 were obtained from the slopes and intercepts of these plots. The temperature dependence of the bimolecular monomer‐initiator reaction is k2 = 5.19 × 1021e−36,000/RT. Instead of the usual behavior, the k4/k51/2 ratio was found to decrease with temperature and the difference of activation energies, (E4 − E5/2), is −1.50 kcal. The temperature dependence of the propagation to square root of the termination rate constant ratio is k4/k51/2 = 6.16e1500/RT. These rather unusual results may be related to the ability of AG polymers in water to form thermally reversible gels; even above the gel melting points, the polymers are considerably aggregated in solution. This would tend to make the bimolecular termination reaction more temperature dependent and also account for the high values (59–69) for the k4/k51/2 ratios. For similar temperatures, the overall rate constants for AG are approximately four times those for acrylamide.
Relationship between the autoacceleration of polymerization rate and conversion in radical polymerization
Authors: Ito Katsukiyo
Published: April 2003

By using a simple treatment for the kinetics of radical polymerization with primary radical termination, the ratio kty/ktx of chain termination rate constant kty at conversion y to that ktx at conversion x and the ratio ktiy/ktix of the primary radical termination rate constant ktiy at conversion y to ktix at conversion x were calculated for the polymerizations of methyl methacrylate and ethyl acrylate in the conversion range 0 to 0.4. kty/ktx and ktiy/ktix were treated by using the following equations based on the variation of conversion:

where g(T,y) is the average fractional free volume of radical chain end at conversion y and absolute temperature and β(T) is a function depending on T, and

where gi(T,y) is the average fractional free volume of primary radical at conversion y and T and βi(T) is a function depending on T. The autoacceleration for the above monomers was successfully interpreted by the above treatment.
Polymerization of aromatic aldehydes. IV. Cationic copolymerization of phthalaldehyde isomers and styrene
Authors: Aso Chuji , Tagami Sanae , Kunitake Toyoki
Published: April 2003

Copolymerizations of three phthalaldehyde isomers (M2) with styrene (M1) were carried out in methylene chloride or in toluene with BF3OEt2 catalyst. The monomer reactivity ratios were r1 = 0.77, r2 = 0 for the meta isomer and r1 = 0.60, r2 = 0 for the para isomer. The second aldehyde group of both isomers did not participate in polymerization and acted simply as the electron‐withdrawing group, thus reducing the cationic reactivity of these monomers. Copolymerization behaviors of the ortho isomer (o‐PhA) were quite different between 0°C and −78°C. At −78°C, o‐PhA preferentially polymerized to yield “living” cyclopolymers, until an equilibrium concentration of o‐PhA monomer was reached. Then, styrene propagated from the living terminal rather slowly. The block structure of the copolymer was confirmed by the chemical and spectroscopic means. In the copolymerization at 0°C, the o‐PhA unit in copolymer consisted both of cyclized and uncyclized units. This copolymer seemed to contain short o‐PhA sequences. The variation of the o‐PhA‐St copolymer structure with the polymerization temperature was explained on the basis of whether the polymerization was carried out above or below the ceiling temperature (−43°C) of the homopolymerization of o‐PhA.
Representation of terpolymer kinetics on triangular coordinates
Authors: Cruise D. R. , Lacombe R. G.
Published: April 2003

The ideal steady‐state kinetics of polymer formation from two or more monomeric species can be derived from basic rate equations by using the theory of discrete parameter Markov chains. Advantages are: (1) steady‐state assumptions are not required; and (2) a particularly lucid graphical visulization is possible for the case where there are three monomeric species.
Quinone copolymerization. I. Reactions of p‐chloranil, p‐benzoquinone, and 2,5‐dimethyl‐p‐benzoquinone with vinyl monomers under free‐radical initiation
Authors: Hauser C. F. , Zutty Nathan L.
Published: April 2003

The free‐radical copolymerization reactions of p‐chloranil, p‐benzoquinone, and 2,5‐di‐methyl‐p‐benzoquinone with vinyl monomers were studied. Reactions of p‐chloranil with styrene yielded copolymers of approximately 1:1 composition under a variety of reaction conditions. A copolymer containing a block of 1:1 of styrene:p‐chloranil and a block of polystyrene was prepared. Several styrene‐like monomers copolymerized with p‐chloranil to yield copolymrs possessing considerable amounts of incorporated quinone. p‐Benzoquinone copolymerized with 1,3‐butadiene and 2‐vinyl‐pyridine to yield copolymers of significant molecular weights. Reactions of 2,5‐dimethyl‐p‐benzoquinone with vinyl monomers did not yield any isolable polymeric products.
The reactive intermediate in acetylene polymerization: Results of quantum chemical calculations on charge delocalization and its consequences
Authors: Manassen Joost , Rein Robert
Published: April 2003

The charge delocalization in the conjugated vinyl intermediates, which are assumed to be the reactive intermediates in acetylene polymerization, is calculated, taking into account σ as well as π electrons. Delocalization is shown to exist, but it is of a different kind for cations and anions. In the anion, the σ charge is localized at the reactive center and the π change is displaced into the system. In the cations, the σ charge flows towards the reactive center and the π charge is more or less unaffected. π‐overlap charges between the carbon atoms are much less affected than in the case of the corresponding allyl type anion and cation. The calculated charge delocalizations are compared with the little experimental evidence there is, and possible implications of σ and π delocalizations on reactivity and specificity of reaction are discussed.
Polymerization by oxidation coupling. I. A study of the oxidation of 2,6‐diphenylphenol to poly(2,6‐diphenyl‐1,4‐phenylene ether)
Authors: White Dwain M. , Klopfer Howard J.
Published: April 2003

The synthesis of poly(2,6‐diphenyl‐1,4‐phenylene ether), by the oxidative coupling of 2,6‐diphenylphenol has been studied. Procedures were found which demonstrated that polymers of very high molecular weight \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {\overline M _n > 200{\rm 000; }\left[ \eta \right]_{{\rm CHCl}_{\rm 3} }^{25^\circ {\rm C}} > 1.1{\rm }{{{\rm dl}} \mathord{\left/ {\vphantom {{{\rm dl}} g}} \right. \kern-\nulldelimiterspace} g}} \right) $\end{document} could be made with a copper‐amine catalyst system. A low nitrogen‐to‐copper ratio (1 N atom/Cu atom) was necessary to obtain the very high molecular weights under the conditions of these reactions. A variety of amines formed active catalysts; the effectiveness of mono‐ and bis‐ primary, secondary, and tertiary amines were compared. Effects of the type of copper halide, reaction temperature, desiccants, addition rates of 2,6‐di‐phenylphenol, and solvents were also examined. Samples of polymer were isolated at different times during the polymerization. Measurements of viscosity, osmotic pressure, light scattering, gel permeation, phenolic hydroxyl groups, and nitrogen content were made on various samples over a range of intrinsic viscosities of 0.05–0.59 dl/g. A very narrow molecular weight distribution was found for all samples. Hydroxyl endgroup analyses indicated that the concentration of phenolic endgroups per mole of polymer does not change during the polymerization. The presence of some side reactions is indicated by nitrogen analyses. The relationships between the intrinsic viscosity in chloroform at 25°C and M̄n and M̄w are: log [η] = −3.97 + 0.727 log M̄n and log [n] = −3.56 + 0.624 log M̄w.
Role of dimethyl sulfoxide as a solvent for vinyl polymerization
Authors: Gupta Satyendra Nath , Nandi Uma Sankar
Published: April 2003

Dimethyl sulfoxide has been used as a solvent in the polymerization of methyl methacrylate and styrene. The chain‐transfer coefficients of the solvent and the values of δ [i.e., (2kt)1/2/kp] in solvent‐monomer mixtures of various compositions were determined. δ was observed to be dependent on the solvent concentration in the case of methyl methacrylate but remained constant in case of styrene. The lowering of the values of δ with increasing solvent concentration in case of methyl methacrylate has been attributed to an interaction between the solvent and poly(methyl methacrylate) radical resulting in lower termination rate.
Chain transfer in ethylene polymerization. V. The effect of temperature
Authors: Mortimer George A.
Published: April 2003

In order to determine the effect of temperature on the chain‐transfer reaction in the free‐radical polymerization of ethylene, chain‐transfer constants were measured for sixteen transfer agents at 130°C and 200°C at 1360 atm. The results were interpreted as ΔE*, the activation energy of the chain‐transfer constant. This value is equal to the difference in activation energy between the transfer step (hydrogen abstraction) and the propagation step (addition to the monomer double bond): ΔE* = Es* − Ep*. Excellent agreement was found between measured ΔE* values determined at 1360 atm pressure and (Es* − Ep*) data for ethyl radical determined in vacuum gas‐phase reactions. Apparently, the ethyl radical is a good model for polyethyl radical. The chain‐transfer constant of ethylbenzene was found to be insensitive to temperature changes, indicating that Ep* = Es* for this compound.
Polymerization of vinyl monomers with salts of bronsted acids
Authors: Yamaguchi Koichi , Minoura Yuji
Published: April 2003

The polymerization of vinyl monomers (N‐phenylmaleimide, acrylamide, acrylonitrile, methyl vinyl ketone, methyl methacrylate, vinyl chloride, and styrene) with sodium salts of Brønsted acids (sodium cyanide, sodium nitrite, sodium hydroxide, etc.) were investigated at 0°C in dimethylformamide. N‐Phenylmaleimide, acrylonitrile, and methyl vinyl ketone were found to undergo polymerization with sodium cyanide, however the other monomers were not polymerized with this salt. In the polymerizations of acrylonitrile and N‐phenylmaleimide with sodium cyanide, the rates of the polymerizations were found to be proportinal to the initiator concentration and to the square of the monomer concentration. The activation energy of acrylonitrile polymerization was 3.7 kcal/mole, and that of N‐phenylmaleimide ws 3.0 kcal/mole. The results of the copolymerization of acrylonitrile with methyl methacrylate at 0°C in dimethyl‐formamide with sodium cyanide confirm that these polymerizations proceeded by an anionic mechanism initiated by the Michael addition reaction of the monomers with the salts. In these polymerizations, the monomer reactivity increased with increase in the e values. The initiation ability of sodium salts increased with increasing pKa of the conjugate acids and with decreasing electronegativity of metal ion in the series of lithium, sodium, and potassium cyanide. The polymerizations took place only in aprotic polar solvents, and did not occur in weak polar solvents and in protonic solvents.
Polymerization of epoxides with dialkylaluminum acetylacetonate catalyst systems
Authors: Kuntz Irving , Kroll W. R.
Published: April 2003

Catalyst systems for the polymerization of epichlorohydrin, propylene oxide, and allyl glycidyl ether have been prepared from pure, separately synthesized dialkylaluminum acetylacetonates (R2Alacac). Adding small amounts of water to R2Alacac gives a catalyst system with enhanced activity. An even more active catalyst system for yielding high molecular weight, epichlorohydrin‐containing polymers is obtained when another organometallic compound is added to the R2Alacac‐0.5 water components. The R2Alacac‐0.5 water‐R2Zn system has been studied in detail. Variation in the molar proportion of water and structural changes in the chelate structure of the R2Alacac component have been examined. Results indicate that the bis‐chelate structure, acac(R)‐Al‐O‐Al(R)acac, plays a major role in catalyst formation. A bimetallic catalyst species containing aluminum and zinc atoms is proposed, with zinc functioning primarily in monomer coordianation and with aluminum involved primarily in polymer chain growth.
Polyelectrolyte behavior and macromolecular properties of sodium amylopectin xanthate in dilute solution
Authors: Pramanik A. G. , Choudhury P. K.
Published: April 2003

Sodium amylopectin xanthate was prepared by xanthation of potato amylopectin in alkaline medium. The pure product was characterized by I2 solution and ultraviolet spectra of the xanthate groups. The polyelectrolyte behavior of Na amylopectin xanthate in aqueous and salt solutions was investigated by viscometry and light scattering. Its polyelectrolyte behavior in aqueous solution as studied viscometrically was completely different from that of Na amylose xanthate, which is characteristic of linear polyelectrolyte molecules. This difference in behavior could be partly due to the branched structure of amylopectin molecule. A dissymmetry study of Na amylopectin xanthate in aqueous and salt solutions, however, showed that Na amylopectin xanthate molecule underwent expansion in water by about 1.3 times its linear dimension in 0.5M NaCl (unperturbed value). Light‐scattering measurements confirmed that the Na amylopectin xanthate molecule had a polydisperse random‐coil chain configuration in 0.25M NaCl. Its molecular weight, end‐to‐end length, and other parameters in salt and alkali solutions were also determined, and the data were then compared with those of Na amylose xanthate in the same media. The solution behavior of Na amylopectin xanthate in 1M NaOH was further investigated and linear expansion factor α, excluded volume factor A2MW/[η], and Flory's hydrodynamic constant φ were evaluated.
Synthetic thermally reversible gel systems. V
Authors: Haas Howard C. , Manning Monis J. , Mach Martin H.
Published: April 2003

Differential thermal analysis has been used to study the fusion of aqueous thermally reversible gels of gelatin and polyacrylylglycinamide (PAG). In the case of gelatin gels, endotherms close to the melting point are readily observed and these are sometimes preceeded by a small exothermic heat of gel reorganization. Calculations are presented to show that breaking of the gelatin gel network requires only a small fraction of the observed endothermic heat of fusion and that most of the heat is required for melting larger crystallites within gelatin aggregates and for perhaps a helix → coil transition. Failure to observe endotherms by DTA over the known temperature range of fusion of PAG gels is consistent with prior measurements and conclusions. The noncrystallinity of PAG gels and soluble aggregates together with a heat of crosslinking of only −5 to −10 kcal/mole of crosslinks places the heat of fusion of PAG gels outside the lower limits of DTA sensitivity.
Carrier mobility and long‐range order in disordered systems. II
Authors: Gutmann F.
Published: April 2003

Recent comments by Fleming on a previous paper dealing with long‐range order in disordered systems are answered. Discrepancies between the results given therein and those obtained by Fleming are discussed and ascribed to different normalization procedures. Experimental evidence for the existence of such order is adduced.
Influence of torsional stiffness upon temperature response of a polymeric chain
Authors: Majerus John N.
Published: April 2003

The influence of torsional stiffness upon the temperature dependence of the mean square end‐to‐end polymer chain distance 〈r〉 was studied parametrically for six different polymer chain models. The equations for 〈r〉, expressed in terms of the torsional potential energy, were differentiated with respect to temperature and the resulting equations were evaluated numerically. The magnitudes and locations of the secondary barrier heights, angular location and magnitudes of the energy minima, angular location of the maximum barrier U0, spacing of the extrema, and the number of extrema were all found to play a significant role in the value of the predicted thermal expansion coefficients. The coefficients were also found to critically depend upon the relative energy ratio and were usually a highly nonlinear function of this ratio. Transitions between positive and negative values of the thermal expansion coefficients were found to exist and to depend upon the torsional potential shape, energy ratio, and the polymer chain model.
Molecular weight distribution in polyacrylamide prepared by a photochemical method
Authors: Venkatarao K. , Santappa M.
Published: April 2003

The molecular weight distribution of polyacrylamide, prepared by uranyl ion‐photosensitized polymerization of acrylamide in visible light of wavelength 436 mμ, was studied in detail. The polymer was fractionated and the experimental integral and differential distribution curves were drawn. The theoretical distribution function was derived from the kinetics of photopolymerization, assuming the rate constants calculated from previous studies. The theoretical and experimental molecular weight distributions were compared. The results support the mechanism proposed for the photopolymerization reaction.
Kinetics of polymerization of N‐carboxy amino acid anhydride in dimethyl sulfoxide
Authors: Oya Masanao , Uno Keikichi , Iwakura Yoshio
Published: April 2003

Various kinds of NCA's were polymerized in dimethyl sulfoxide (DMSO). DL‐Alanine NCA polymerized at a fast rate without initiator, the rate being represented by Rp1 = k[M]1/2. When the polymerization was carried out in chloroform in the presence of DMSO, the rate was represented by the equation, Rp2 = K2[M][DMSO]1/2.

Glycine NCA and DL‐α‐amino‐n‐butyric acid NCA also polymerized at a fast rate in DMSO without initiator. On the other hand, N‐methylglycine NCA, DL‐ and L‐valine NCA and DL‐ and L‐leucine NCA did not polymerize in DMSO without initiator.
Statistical study of the effect of variation of bimolecular rate constant in condensation polymerization
Authors: Nanda V. S. , Jain S. C.
Published: April 2003

We investigate the effect of variation of bimolecular rate constant with chain length on condensation polymerization by a statistical approach. The variation of reactivity with chain length is simulated in the present study by assigning appropriate weight factors to different species. Formal expressions for the size distribution and various averages of interest have been obtained. Some simple cases are then analyzed and comparisons with the experimental results of Taylor and Howard are carried out.
Polybenzopinacols. I. Photolytic coupling of aromatic diketones
Authors: Higgins Jerry , Johannes Arland H. , Jones Joe F. , Schultz Ronald , McCombs D. A. , Menon C. S.
Published: April 2003

Low molecular weight polybenzopinacols were obtained by the photolytic coupling of m‐ and p‐dibenzoylbenzene and 4,4′‐dibenzoyldiphenyl ether in isopropanol, tetrahydrofuran–isopropanol, benzene–isopropanol, and benzene–ethanol solutions. The polypinacols were soluble in common organic solvents such as tetrahydrofuran, ether, and benzene. The inherent viscosities ranged from 0.06 to 0.14. Average molecular weight (M̄n) data indicated that the polymers were mostly dimers and trimers.
Copolymers of 1‐methylcyclopropene
Authors: Anderson W. S.
Published: April 2003

1‐Methylcyclopropene (MCP) copolymerizes rapidly with acrylic and vinyl monomers to form soluble, high molecular weight products containing enchained cyclopropane rings. The high electron availability in the cyclopropene double bond promotes one‐to‐one alternating copolymerization with sulfur dioxide, maleic anhydride, acrylic acid, acrylonitrile, dialkyl fumarates and acrylic esters. Nonalternating copolymers are obtained with vinyl chloride and vinyl acetate, and attempted copolymerization fails entirely with styrene, α‐methylstyrene and isoprene. This pattern of copolymerization reactivity resembles that of highly compressed ethylene. Methylcyclopropene copolymers have high glass temperatures in spite of the small size of the MCP unit. The combination of high Tg and small size allows preparation of copolymers with high Tg having a wide range of ductilities and cohesive energy densities.
Four‐center type photopolymerization in the solid state. IV. Polymerization of α,α′‐dicyano‐p‐benzenediacrylic acid its derivatives
Authors: Nakanishi Fusae , Hasegawa Masaki
Published: April 2003

The solid‐state photopolymerization of α,α′‐dicyano‐p‐benzene diacrylic acid (p‐CBA) series has been studied. p‐CBA, its esters, amide, and a few other cyano derivatives were prepared and new polymers were obtained from p‐CBA alkyl esters on irradiation of ultraviolet or visible light. Though the polymerization behavior differs with each monomer, polymerization proceeds in essentially the same manner as in the 2,5‐distyrylpyrazine (DSP) and p‐benzenediacrylic acid (BDA) series: the reaction proceeds topochemically forming polymer with a cyclobutane ring in the main chain. Properties of high polymer are typical of cyclobutane‐containing polymer. That is, they are highly crystalline with high melting temperature and a limited solubility. The study on this series of compounds, as well as the DSP and p‐BDA series, supports the generalization that solid‐state dimerization can be extended to solid‐state photopolymerization of compound having two dimerizable units in a molecule.
Characterization and polymerization of thioacetone
Authors: Lipscomb R. D. , Sharkey W. H.
Published: April 2003

The thioketo and thioenol tautomers of thioacetone have been separated by gas chromatography and characterized by infrared and NMR spectra at low temperatures. The pure thioketo tautomer polymerizes rapidly at room temperature, but the thioenol tautomer does not. At room temperature, the thioenol gradually disappears, probably by tautomerization to the reactive thioketo form, which then polymerizes. Attempts to copolymerize thioacetone with vinyl and diene monomers were not successful.
Cyclopolycondensation. XIII. New synthetic route to fully aromatic poly(heterocyclic imides) with alternating repeating units
Authors: Dokoshi Noriaki , Tohyama Shunroku , Fujita Saburo , Kurihara Masaru , Yoda Naoya
Published: April 2003

Fully aromatic poly(heterocyclic imides) of high molecular weight were prepared by the cyclopolycondensation reactions of aromatic diamines with new monomer adducts prepared by condensing orthodisubstituted aromatic diamines with chloroformyl phthalic anhydrides. The low‐temperature solution polymerization techniques yielded tractable poly(amic acid), which was converted to poly(heterocyclic imides) by heat treatment to effect cyclodehydration at 250–400°C under reduced pressure. In this way, the polyaromatic imideheterocycles such as poly(benzoxazinone imides), poly(benzoxazole imides), poly(benzimidazole imides) and poly(benzothiazole imides) were prepared, which have excellent processability and thermal stability both in nitrogen and in air. The poly(amic acids) are soluble in such organic polar solvents as N,N‐dimethyl‐acetamide, N‐methylpyrrolidone, and dimethyl sulfoxide, and the films can be cast from the polymer solution of poly(amic acids) (ηinh = 0.8–1.8). The film is made tough by being heated in nitrogen or under reduced pressure to effect cyclodehydration at 300–400°C. The polymerization was carried out by first isolating the monomer adducts, followed by polymerization with aromatic diamines. On subsequently being heated, the open‐chain precursor, poly(amic acid), undergoes cyclodehydration along the polymer chain, giving the thermally stable ordered copolymers of the corresponding heterocyclic imide structure.
Halatopolymers
Authors: Economy J. , Mason J. H. , Wohrer L. C.
Published: April 2003

The polymeric character of a series of salts derived from divalent metal ions and organic dibasic acids has been investigated. On melting, these salts form extremely viscous melts which cool to amorphous solids with polymerlike properties and excellent thermal stabilities. This change from a salt to a polymerlike structure appears to be novel and has been termed a halatopolymeric transformation. Halatopolymers are unique in that they have no end groups in the traditional sense. Essentially, the metal carboxylate groups undergo a rapid interchange to afford an association equilibrium of long chains. Studies of the effects of chain modifiers on a calcium sebacate melt at 386°C have indicated that on a time‐average basis the association consists of approximately ten repeat units.
Synthesis and properties of polyamides and polyesters from neocarboranedicarboxylic dichloride
Authors: Korshak V. V. , Bekasova N. I. , Komarova L. G.
Published: April 2003

Polyamides and polyesters based on neocarboranedicarboxylie dichloride and previously not described have been prepared by low‐temperature polycondensation in solution and characterized. In preparing the polyamides, the following diamines were used: benzidine, hexamethylenediamine, m‐phenylenediamine, p‐phenylenediamine, 4,4′‐diaminodiphenyl ether, 4,4′‐diaminodiphenylmethane, 4,4′‐diaminodiphenyl sulfide, and hydroquinone diaminodiphenyl ester. Polyesters were obtained by using the following diols: phenolthalein, hydroquinone, 4,4′‐dihydroxydiphenylpropane, 9,9‐dihydroxydiphenylfluorene, 1,6‐hexanediol, and ethylene glycol. The resulting neocarborane polyesters melt and are easily soluble in tetrahydrofuran, amide solvents, and chloroform. The neocarborane polyamides described do not melt, are readily soluble in tetrahydrofuran and dimethylformamide, and form transparent films; they are thermostable in an inert at mosphere at high temperatures.
Stereospecific polymerization of methacrylonitrile. VI. Effect of esters as a complexing agent with diethylmagnesium catalyst
Authors: Joh Yasushi , Kurihara Seiki , Sakurai Toshio , Tomita Tatsunori
Published: April 2003

The stereospecific polymerizations of methacrylonitrile with diethylmagnesium were carefully studied by using various ethers as complexing agents. The complexed ethers exhibit a beneficial effect on the stereoregularity of the resulting polymer, namely, the crystallinity increased by using ethers as a complexing agent. The polymerization rate and the molecular weight of the polymer also increased by using ether‐complexed catalysts. The polymerization behavior was studied with the dioxane–diethylmagnesium complex as a typical complexed catalyst. The behavior was mostly similar to that of the diethymagnesium alone, that is, the rate of the polymerization increased in proportion to monomer concentration, and the solubility index increased with increasing monomer concentration. Interestingly, the viscosity of the acetone‐insoluble fraction increased with increasing monomer concentration, while that of the acetone‐soluble fraction was independent of monomer concentration. This is explained by considering that the catalyst has at least two kinds of catalytic species, one being the species that produces the crystalline polymer by a coordinated anionic polymerization, another being the one from which an amorphous polymer is obtained by a conventional anionic mechanism. The fact that the viscosity of the polymer decreased with increasing the initiator concentration is explained in terms of chain trasfer to the initiator. In case of diethylmagnesium alone, the viscosity of the polymer is independent of the initiator concentration.
Polycondensation of benzyl chloride and its derivatives: A study of the reaction at different temperatures
Authors: Montaudo G. , Finocchiaro P. , Caccamese S. , Bottino F.
Published: April 2003

The polycondensation reactions of benzyl chloride, α‐chloroethylbenzene, and benzhydryl chloride in the presence of SnCl4 or AlCl3 as catalysts have been investigated in the temperature range between +80° and −135°C. Polycondensations of benzyl chloride and α‐chloroethylbenzene are quite similar in the reaction kinetics and are thought to occur by the same displacement mechanism. Polycondensation of benzhydryl chloride, however, seems to involve the formation of benzhydryl carbonium ions. At low temperatures linear polymers tend to be formed, in contrast with branched polymers produced at room temperature. Steric effects are found to play a major role in protecting polymers from branching at lower temperatures.

Polybenzyl polymers are found to be less linear than poly(‐α‐methylbenzyl), even when prepared at −135°C.
The vacuum and oxidative pyrolysis of poly‐p‐xylylene
Authors: Jellinek H. H. G. , Lipovac S. N.
Published: April 2003

Poly‐p‐xylylene prepared by pyrolysis of di‐p‐xylylene has been degraded under vacuum and in the presence of oxygen as a function of temperature and oxygen pressure. The vacuum pyrolysis is mainly due to “abnormal” structures. Volatiles are initially produced quite slowly, but the reaction accelerates subsequently. Arrhenius equations were derived for various ranges of volatile formation. A mechanism has been formulated consisting of random chain scission followed by depropagation (dimers to pentamers); simulatanously another zip reaction produces hydrogen. The thermal, oxidative degradation has been studied above and below the softening point of the polymer as a function of oxygen pressure. A first‐order reaction of volatile formation due to “abnormal” chain scission is followed by normal chain scission, which is also first order. The postulated mechanism leads initially to hydroperoxide formation. Arrhenius equations for volatile formation are different below and above the softening point. Oxygen consumption also follows a first‐order reaction with an energy of activation of 31.5 kcal/mole.