bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deformation mechanism of polyethylene spherulite
Authors: Oda Takashi , Nomura Shunji , Kawai Hiromichi 
Published: April 2003

AbstractA deformation mechanism for polyethylene spherulites has been proposed which is based on the affine transformation method. Individual crystal lamellae are taken as the orientation units within the spherulites and are allowed to rotate around the a‐ and b‐ axes of the crystal. Deductions based on this model and on previous models are compared with experimental results obtained with four kinds of polyethylene film. These results agree fairly well with the predictions of the present model and suggest that the plastic deformation of crystal lamellae by gliding along the (110) plane predominates over the untwisting of crystal lamellae at the initial stage of deformation.
Solvent effects in anionic copolymerization. II. Molecular orbital treatment for the pair: Styrene–methylstyrene
Authors: O'Driscoll K. F. , Yonezawa T. , Higashimura T. 
Published: April 2003

AbstractA model is proposed for the transition state of the anionic copolymerization of styrene and p‐methylstyrene in hydrocarbon solvent with lithium counterion. An LCAO‐MO treatment which considers the effect of the positive counterion on the negative chain end is used to calculate the electrostatic and the π electron resonance contributions to the activation energies of the four propagation reactions. The electron contributions to the activation energies are also calculated for the propagation reactions of free ions, i.e., in the absence of a counterion. The previously determined rate constants in benzene and tetrahydrofuran are then compared with the results of these calculations.
Synthesis and structure of polyglyoxal
Authors: Brady William T. , O'Neal Hubert R. 
Published: April 2003

AbstractThe polymerization of glyoxal has been carried out in the presence of sodium naphthalene in THF at −78°C. The polyglyoxal decomposed at 150°C. and was slightly soluble in water and alcohol. The polymer was readily acetylated with acetic anhydride to yield a material that decomposed at about 290°C. Structure elucidation of the glyoxal polymer indicated that it had a polyacetal type of structure containing pendant enol groups and also a cyclic chelated structure involving hydrogen bonding between an enolic hydroxy group and a pendant carbonyl group.
Copolymerization of α‐olefins with ω‐halo‐α‐olefins by use of Ziegler catalysts
Authors: Bacskai R. 
Published: April 2003

AbstractThe copolymerization of α‐olefins with ω‐halo‐α‐olefins by use of Ziegler catalysts has been investigated. It was found that ω‐halo‐α‐olefins deactivate the catalyst, thus resulting in low copolymer yield and reduced molecular weight. The deactivation is caused by hydrogen halide formation which is greatly facilitated in the case of the allyl halides and 6‐halo‐1‐hexenes. The different degrees of deactivation were interpreted by considering the ease of carbonium ion formation from the various ω‐halo‐α‐olefins. The copolymer yields were considerably improved when a catalytic amount of a Lewis base was added to the polymerization system. It is proposed that the added Lewis base, by decreasing the Lewis acid character of the catalyst, suppresses the decomposition of the ω‐halo‐α‐olefin leading to hydrogen halide formation. Depending on the Ziegler catalyst employed, the copolymers of α‐olefins and ω‐halo‐α‐olefins can be either crystalline or amorphous solids. The halogen, especially the bromine in the copolymers, is reactive in nucleophilic substitution reactions. Reaction with amines gave polymers which could be dyed by acid dyes.
Semiquantitative aspect of short branch detection by using polyelectrolyte expansive effects
Authors: Pasika W. M. , Cragg L. H. 
Published: April 2003

AbstractLinear and branched dextran polyelectrolyte reduced viscosity–concentration curves, obtained by employing a solvent which contained a low concentration of simple electrolyte, were characterized by means of a set of relative expansion ratios, \documentclass{article}\pagestyle{empty}\begin{document}$ R_{nc_m } $\end {document} . The sets of \documentclass{article}\pagestyle{empty}\begin{document}$ R_{nc_m } $\end {document} for branched and linear dextran polyelectrolyte samples of identical degree of substitution, whose reduced viscosity–concentration curves were determined in the same solvent, did not differ. This is interpreted as indicating that the same expansive mechanism operated in the linear and branched polyelectrolyte systems when they were diluted. Plots of \documentclass{article}\pagestyle{empty}\begin{document}$ R_{nc_m } $\end {document} versus absolute concentration for linear and branched polyelectrolyte samples (of identical degrees of substitution, of different degrees of substitution and whose reduced viscosities were determined in solvents of different simple electrolyte concentrations) gave straight lines with a common intercept on the ordinate axis but with different slopes. It is suggested that the slope factor or p values of these lines might be employed as a means of detecting and measuring short branching in polymers convertible to polyelectrolytes.
Studies in condensed phosphates. Part VIII. Complex potassium polymetaphosphates of calcium, zinc, and cadmium
Authors: Mehrotra R. C. , Vyas P. C. 
Published: April 2003

AbstractDerivatives with the formulas [K4Ca(PO3)6]n, and [K4Cd(PO3)6]n have been prepared by heating together mixtures of KH2PO4, CaO, (or ZnO or CdO), and (NH4)2HPO4 in the mole ratio of 4 : 1 : 2 at 800°C. for 1 hr. The number‐average molecular weights of these derivatives have been measured by endgroup titration. Their conductance has been measured in aqueous solution of varying concentration, and their properties compared with those of Graham's salt and its complex derivatives prepared under similar conditions.
Thermodynamic stability of polymer crystals. III. Torsional and longitudinal chain vibrations
Authors: Peterlin A. , Reinhold Chr. 
Published: April 2003

AbstractThe free energy density of a folded‐chain crystal varies with the length of the straightchain section between consecutive folds. It is always minimum at infinite length. Another minimum at finite length L appears below a critical temperature T0 which among other things depends on the surface energy of the fold‐containing planes. This minimum is a result of the smearing out of the nonharmonic lattice potential energy field by the incoherent vibrations of adjacent chains. In the present paper the simultaneous influence of both longitudinal and torsional vibrations of polyethylene chains in the orthorhombic lattice is considered. Due to the relative smallness of the amplitude of the potential energy for chain translation in comparison to that for chain rotation the calculated equilibrium length L at any temperature does not appreciably differ from the value obtained formerly for the torsional vibrations only. L increases with temperature and is maximum at the critical temperature. With increasing surface energy the equilibrium long period at constant temperature increases, and the critical temperature decreases. The calculated values fit fairly well the experimental data of polyethylene crystals grown from dilute solution if one admits that the surface energy varies slightly from solvent to solvent.
Electron traps in polyethylene
Authors: Partridge R. H. 
Published: April 2003

AbstractQualitative and quantitative results from previous studies of the thermoluminescence induced in polyethylene by irradiation are used in an attempt to deduce the main polyethylene electron traps. It is concluded that the most probable traps are the molecular chains themselves, the different degrees of molecular motion in different structural regions of polyethylene being responsible for the untrapping of the trapped electrons at different rates and hence the appearance of multiple glow peaks in the glow curve. An explanation is given for the correspondence between the activation energies of thermoluminescence, radiation induced electrical conductivity, and molecular chain motion (as measured by NMR) in polyethylene.
Melting of homopolymers under pressure
Authors: Baer Eric , Kardos John L. 
Published: April 2003

AbstractThe effect of pressure on the melting of polyethylene, polypropylene, poly(ethylene oxide), and poly‐3,3‐bischloromethyloxacyclobutane (Penton), has been studied up to 3000 atm. The melting temperature–pressure curves for all polymers studied rose indefinitely with pressure, thus behaving in a manner similar to that previously reported for long‐chain hydrocarbons. For polyethylene, analysis of the total entropy change on melting, in terms of changes in configurational and volume entropies showed that the percentage of the total entropy change due to change in configurational entropy increased rapidly with pressure, attaining a value of 90% at 3000 atm. The changes in the configurational entropies of melting for polypropylene, poly(ethylene oxide), and Penton were subsequently shown to be lower than that of polyethylene suggesting more melt order. This could arise from helical conformations in the melt for polypropylene and polyethylene oxide and from a stabilized planar zigzag conformation in the Penton melt. A pronounced broadening of the melting range with pressure was attributed to pressuresensitive transitions which are known to occur near the melting temperature and also to the effect of molecular weight distribution.
Integral and differential binary copolymerization equations
Authors: Meyer Victor E. , Lowry George G. 
Published: April 2003

AbstractAn analytic solution to Skeist's copolymerization equation has been obtained for the case of binary copolymerization. From this solution, a differential copolymer composition equation is also derived. For given values of the reactivity ratios, these equations then permit the convenient calculation of expected binary copolymerization behavior as a function of conversion. Critical conditions leading to incompatible copolymerizations are also discussed.
Homogeneous ionic copolymerization. A study of solvent effects in the styrene systems
Authors: Overberger C. G. , Chapman T. M. , Wojnarowski T. 
Published: April 2003

AbstractThe effect of solvent in the homogeneous anionic copolymerization of styrene with p‐methylstyrene, p‐tert‐butylstyrene, and m‐methylstyrene has been determined. In nonpolar media where the gegenion is lithium, a nonhomogeneous distribution exists with the more basic monomer in higher concentration at the growing chain end which shows as an enhanced relative reactivity. This is depressed by the addition of a small amount of more polar solvent. The influence of temperature as a function of solvent has been determined for selected anionic systems. In nonpolar media, an increase of temperature favors incorporation of the less basic monomer whereas a more polar solvent has only a small effect and favors a more ideal copolymerization. In cationic copolymerization the effect of hyperconjugation has been demonstrated. This effect of hyperconjugation appears to be enhanced in polar media. The cationic copolymerizations of styrene with p‐tert‐butylstyrene in nitrobenzene shows a steric hindrance of the bulkier monomer on its incorporation into the copolymer. Determination of reactivity ratios as defined for radical systems does not fully characterize ionic copolymerizations.
Existence of long‐lived radicals in the γ‐radiation induced polymerization of ethylene
Authors: Machi Sueo , Hagiwara Miyuki , Gotoda Masao , Kagiya Tsutomu 
Published: April 2003

AbstractIn the γ‐radiation‐induced bulk polymerization of ethylene under high pressure, the growing polymer radical is shown to have a long lifetime at low temperatures (30°C.). Separation of the propagation reaction from other elementary reactions is possible. During the propagation reaction the molecular weight of the polymer increases with polymer yield when irradiated with an extremely low dose rate. At elevated temperatures (100°C.), the lifetime of the growing polymer radical is not prolonged.
Preparation and polymerization of vinyl esters of chloro‐ and hydroxystearic and eicosanoic acids
Authors: Marvel C. S. , Griffith J. H. , Comp J. L. , Applewhite T. H. , Goldblatt L. A. 
Published: April 2003

AbstractHomopolymers and copolymers with vinyl acetate and vinyl chloride have been prepared from the vinyl esters of 9‐chlorostearic acid, 12‐chlorostearic acid, 14‐chloroeicosanoic acid, 9‐hydroxystearic acid, 9,10‐dihydroxystearic acid, 14‐hydroxyeicosanoic acid, and 8‐(1,3‐dioxylone‐2‐yl) octanoic acid.
Molecular motions of polymers having helical conformation. I. Poly(ethylene glycol) and polyoxymethylene
Authors: Hikichi Kunio , Furuichi Jiro 
Published: April 2003

AbstractIn order to study molecular motion characteristic of a helical polymer, proton magnetic resonance spectra and the complex dielectric constants ε* for a wide frequency range have been measured in the temperature region between 90°K. and the melting point for poly(ethylene glycol), which is thought to be helical in the solid state. The molecular weights of the samples are 4000, 1000, and 400. These results suggest that a molecular motion such as rotation or oscillation is able to occur even in crystalline regions well below the melting point. The temperature at which this type of molecular motion begins seems to be independent of the molecular weight of the samples, although the melting point is found to depend markedly on molecular weight. X‐ray and dilatometric measurements were carried out for the same samples and indicate the absence of a crystalline phase transition (first‐order transformation) at the temperature region where the narrowing of the NMR line width of PEG is observed. The results for another helical polymer, polyoxymethylene, are also presented.
Dye‐sensitized polymerization of vinyl monomers in aqueous solution
Authors: Sheriff A. I. , Santappa M. 
Published: April 2003

AbstractThe kinetics of the polymerization of the vinyl monomers methyl methacrylate, methyl acrylate, and acrylonitrile sensitized by dye‐reducing agent systems have been studied systematically. The systems were irradiated with light of 350–450 mμ wavelength. The induction period before the onset of polymerization was kept to a minimum by suitable experimental conditions. All the experiments were conducted in the presence of oxygen. The redox system sodium fluorescein (Uranine)–ascorbic acid was used for polymerization. The systems were buffered with phosphate buffer. The effects of temperature, viscosity, etc., on the reaction system were studied. The course of the reactions was followed by the measurements of rate of monomer disappearance (gravimetrically), rate of dye disappearance (spectrophotometrically) and the chain length of the polymer formed (viscometrically). Light intensity, wavelength, monomer concentration, dye concentration, reducing agent concentration, temperature, etc., were variable. The tentative kinetic scheme proposed is examined in the light of the experimental results. The values for the specific rate constants for the various steps have been evaluated.
Kinetics of the initiation of styrene polymerization by n‐butyllithium
Authors: O'driscoll K. F. , Ricchezza E. N. , Clark J. E. 
Published: April 2003

AbstractThe reaction between styrene and n‐butyllithium in benzene has been studied by spectrophotometry and calorimetry at 25°C. It was observed that the initiation of polymerization was first‐order in styrene and one‐third‐order in butyllithium at styrene concentrations of 0.5 mole/l.. and that addition of butyllithium to styrene solutions caused an evolution of 1.7 kcal./mole of butyllithium. It was also noted that the rate of initiation was approximately an order of magnitude larger than that previously reported in very dilute styrene solutions (0.03 mole/l.) and comparable butyllithium concentrations. It is concluded that styrene stabilizes trimeric butyllithium relative to its hexamer by a nonstoichiometric, exothermic solvation process.
Anionic polymerization of ω‐lactam. Part I. Polymerization of ε‐caprolactam by alkaline catalysts and ketenimines
Authors: Yasumoto Takaya 
Published: April 2003

AbstractKetenimines have been found to be useful cocatalysts for the alkaline polymerization of ε‐caprolactam. The induction period preceding the start of the reaction is shortened by addition of a ketenimine, and the polymerization rapidly proceeds at low temperature below the melting point of the polymer. A reaction mechanism is proposed for the polymerization of ε‐caprolactam with alkaline catalyst and ketenimine, which involves a formation of a reactive N‐imidoyl lactam from ketenimine and lactam, and chain propagation by the stepwise addition of anionic lactam at the end of the molecule leading to the polymer. This mechanism is supported by the experimental fact that imino chloride has the same effect as ketenimine on the alkaline polymerization of ε‐caprolactam. The conditions for the polymerization have been carefully investigated. Both conversion and relative viscosity of polymer diminish with increasing concentration of ketenimine and also with increasing reaction temperature.
Vinyl polymerization. XCI. Polymerization of styrene initiated by nickel peroxide
Authors: Nakata Tadashi , Otsu Takayuki , Imoto Minoru 
Published: April 2003

AbstractA study of the radical polymerization of styrene initiated by nickel peroxide (Ni‐PO) as a solid initiator has been made. The rate of polymerization (Rp) was found to be expressed by the equation: Rp = k[Ni‐PO]1/2[Styrene]3/2. This equation could be understood by considering that the radical polymerization by Ni‐PO is initiated through the interaction between the monomer and the Ni‐PO initiator and terminated by the ordinary bimolecular termination mechanism. By extracting the resulting polystyrene with methyl ethyl ketone (MEK), the MEK‐insoluble polymer, which was confirmed by infrared spectra and x‐ray diffraction analyses to be isotactic polystyrene, was isolated. The amount of the isotactic polymer increased as the polymerization temperature decreased. The results obtained in the present study indicate that the stereospecific absorption (π‐complex formation) of the monomer on the solid Ni‐PO initiator might be important for producing an isotactic polystyrene.
Preparation and polymerization of addition compounds of unsaturated tertiary phosphine oxides
Authors: Welch F. J. , Paxton H. J. 
Published: April 2003

AbstractComplexes of vinyldiphenylphosphine oxide, vinyldi‐n‐butylphosphine oxide, and trans‐1‐propenyldiphenylphosphine oxide have been prepared with salts of Zn(II), Hg(I), Sb(III), Sn(IV), Ti(IV), Fe(III), and U(VI). The observed shifts in the phosphoryl stretching frequency on complex formation were similar to the values reported for corresponding complexes with triphenylphosphine oxide. The polymerization behavior of these compounds in the presence of free‐radical and ionic intiators is similar to that of the unsaturated phosphine oxides themselves. In spite of high salt content, the polymers form clear plaques on molding, and they are completely soluble in appropriate organic solvents.
Crosslinking of copolymers containing N,N‐dimethylacrylamide
Authors: Needles H. L. , Whitfield R. E. 
Published: April 2003

AbstractAqueous solutions of N,N‐dimethylacrylamide–acrylic copolymers crosslink in the presence of peroxydisulfates at elevated temperature. It is shown that effectiveness of crosslinking depends on the amount of N,N‐dimethylacrylamide present in the copolymer, being quite effective with as little as one unit of N,N‐dimethylacrylamide in each eleven units of copolymer. Dilute solutions of these copolymers are slowly degraded initially by peroxydisulfate, and then begin to crosslink after a few minutes. Crosslinking is believed to proceed via sulfate‐ and hydroxyl‐radical attack of N‐methyl in the polymers to yield N‐methylol derivatives capable of crosslinking with other reactive sites.
Glass temperatures of some acrylic polymers
Authors: Krause Sonja , Gormley James J. , Roman Nicholas , Shetter John A. , Watanabe Warren H. 
Published: April 2003

AbstractDilatometrically determined glass transition temperatures and thermal expansion coefficients of 47 different polymers, most of them acrylics, are reported. The experimental values are discussed in terms of the effect of side‐chain flexibility, bulkiness, and polarity on the glass transition temperature and are compared with the isofree‐volume theory of the glass transition temperature, as recently set forth by Simha and Boyer. Possible reasons for the poor agreement with this theoretical treatment are discussed. The effect of equilibrium time at each temperature during a dilatometric run was determined for one sample, polystyrene, which was measured both in the usual way and with long equilibrium times (over a week) at each temperature, yielding glass temperatures of 97 and 89°C. for the usual and for the long equilibrium times, respectively.
Terpolymerization of olefins and cis, cis‐1,5‐cyclo‐octadiene with sulfur dioxide and carbon monoxide
Authors: Frazer A. H. 
Published: April 2003

AbstractThe terpolymerization of propylene, 1‐butene, isobutene, and cis, cis‐1,5‐cyclooctadiene with sulfur dioxide and carbon monoxide at elevated temperatures and pressures has been studied. With the α‐olefins, at carbon monoxide pressures of 1000 and 3000 atm. and temperatures above the ceiling temperature of the particular olefin‐sulfur dioxide system, terpolymers of the olefin, sulfur dioxide, and carbon monoxide were obtained. With the diene, at these carbon monoxide pressures over a broad temperature range, similar terpolymers were obtained. All of these systems exhibited a ceiling temperature. The properties of these terpolymers were determined, and the structures and mechanism for the preparation of such structures postulated.
Studies on alcohol‐modified transition metal polymerization catalysts. I. Infrared studies
Authors: Marchessault R. H. , Chanzy H. , Hider S. , Bilgor W. , Hermans J. J. 
Published: April 2003

AbstractThe interaction of titanium tetrachloride and alcohols in benzene and carbon tetrachloride has been studied by means of infrared spectroscopy. A “continuous variation” study of various absorption bands has allowed establishment of two different interactions: one involving a 1:1 alcohol‐titanium tetrachloride ratio and another at 3:1. High‐resolution spectroscopy in the 3 μ region for the latter indicates well‐defined hydrogen bonding of the intramolecular kind. This has been interpreted in terms of the alcohols being both reacted and coordinated in a titanium complex. Significantly, polymerization activity of the titanium compound decreases sharply when alcohol is in molar excess and goes to zero at a 3:1 ratio. The effect of added aluminum triethyl on the infrared spectrum of the propanol–titanium tetrachloride 3:1 complex in the 3 μ region was observed. Significant changes in the OH stretching modes were noted. Interaction spectra of propanol–methyl titanium trichloride were also recorded.
Radiation grafting of vinyl monomers to wool. Part I
Authors: Stannett V. , Araki K. , Gervasi J. A. , McLeskey S. W. 
Published: April 2003

AbstractA number of vinyl monomers have been grafted to wool by using the mutual radiation technique. Styrene has been studied in considerable detail in dioxane solution; water or methanol was found to be necessary for successful grafting. It is believed that these function as swelling agents, enabling the monomer to diffuse to the active centers created in the wool by the radiation. The rate of grafting always went through a maximum and then leveled off to a slower rate. This is believed to be due to the slow build‐up of the radical population, leading eventually to a diffusion‐controlled rate of grafting. Considerable post‐polymerization grafting was found to take place. Acrylonitrile and a number of allyl monomers were also successfully grafted to wool by the mutual radiation method in dimethylformamide solution. Again water or methanol was found to be necessary; the grafting rate leveled off close to zero at a degree of grafting depending on the amount of swelling agent present.