bluuebunny/crossref_metadata_2025_split huggingface dataset:
How Ticl3 Catalysts Control the Texture of As‐Polymerized Polypropylene
Authors: Hock Charles W. 
Published: April 2003

AbstractWithin a family of catalyst systems wherein TiCl3 was made by mixing TiCl4 and aluminum alkyl solutions, the primary particles of TiCl3 were usually thin, flat polygons with average diameters ranging from 300 to 1000 A. Even in unused catalyst these primary catalyst particles were bound together into large (∼30 μ) secondary particles. A small amount of polyolefin which formed from the aluminum alkyl reducing agent aided in cementing the particles. When propylene monomer was introduced to a slurry of secondary catalyst particles in a liquid hydrocarbon, polymer formed at the surfaces of the ultimate solid particles. The resulting polymer flakes, i.e., particles of as‐polymerized polypropylene, were several times larger than the secondary catalyst particles from which they grew but they retained the same shape. The primary catalyst particles, not visibly altered by the catalytic reaction which they propagated, were distributed uniformly throughout the flake polymer. Each polymer flake consisted of many thousands of cohering roundish flakelets about a 1/2 μ in diameter. How the flakelets are agglomerated and the extent to which they are coalesced accounts for the flakes' texture. The basic morular structure of the flakes, which was manifested further by their papillary surfaces, was not altered by purification procedures which removed catalyst from the nascent polymer. Although all the flakes had the same basic small‐scale structure there were significant coarse textural dissimilarities among them. Some catalysts gave rise to flakes with an open porous texture: other catalysts gave rise to flakes which were dense and compact. In the former, the flakelets were less tightly appressed, and fissures and slits were larger and more numerous than in the latter. The genetic basis for the differences in flake texture resides in the parent catalyst. Secondary catalyst particles whose constituent primary particles are held together in a dense mass produce dense flakes. Conversely, loose aggregates of primary particles produce flakes with loosely aggregated flakelets. Briefly, dissimilarities in catalyst structure carry over to the texture of the flake progeny. Such textural differences contribute importantly to properties of the flake polymer.
Thermodynamics of crystalline linear high polymers. IV. The effect of ethyl, acetate, and hydroxyl side groups on the properties of polyethylene
Authors: Bodily David , Wunderlich Bernhard 
Published: April 2003

AbstractCopolymers of ethylene with vinyl acetate, vinyl alcohol, and butene‐1 have been investigated by differential thermal analysis. The method of fast heating is used to approximate a zero entropy production heating path. The activity of crystallizable units in the melt, the crystallinity, and the a‐axis spacings are determined and compared with previous results for copolymers of ethylene and propylene and carbon monoxide. Carbonyl and hydroxyl groups form point defects, forming solutions in both the crystalline and amorphous regions. Methyl, ethyl, and acetate groups form large amorphous defects. The maximum melting point of polyethylene is calculated to be 142.6°C.
Fractionation of polyethylene by gel permeation chromatography
Authors: Nakajima Nobuyuki 
Published: April 2003

AbstractThe performance of the gel permeation chromatography (GPC) technique was studied with several commercial samples of linear high density polyethylene. A comparison of these data was made with those obtained from the elution column technique based on fractional dissolution. GPC gave reproducible fractionation data in the molecular weight range of 103–106. These data were obtained from two columns in series with nominal capacity of 1–104 and 1–106A. Polyethylene fractions of known molecular weights are required as calibration standards and for many commercial polyethylenes it is necessary to increase sensitivity at molecular weight higher than 106.
Unperturbed dimensions of polystyrene derivatives. II. Poly‐3,4‐dichlorostyrene and poly‐p‐cyclohexylstyrene
Authors: Kuwahara Nobuhiro , Ogino Kazuyoshi , Konuma Makoto , Iida Noriko , Kaneko Motozo 
Published: April 2003

AbstractThe relationship of intrinsic viscosity to the number‐average molecular weight has been obtained for poly‐3,4‐dichlorostyrene and poly‐p‐cyclohexylstyrene in a few solvents. Values of (〈L2〉0/M)1/2 have been estimated for poly‐3,4‐dichlorostyrene and poly‐p‐cyclohexylstyrene through the use of the treatment of Stockmayer and Fixman. The values of (〈L〉0/M)1/2 have been obtained as 2.18 ± 0.08 and 2.52 ± 0.07 for poly‐3,4‐dichlorostyrene and poly‐p‐cyclohexylstyrene, respectively. The σ value of a series of polystyrene derivatives has been found to increase with the bulk of side groups. This seems to indicate that the σ value is mainly determined by the steric repulsion between side groups.
Poly(γ‐alkyl glutamates). I
Authors: Sugai S. , Kamashima K. , Makino S. , Noguchi J. 
Published: April 2003

AbstractGood yields of some crystalline γ‐alkyl esters of L‐glutamic acid were obtained by carrying out the esterfication with a small (20–50 mole‐%) excess of alcohol in aqueous hydrochloric acid or 60–80% sulfuric acid followed by neutralization with an alkaline solution. This new method made it possible to synthesize various γ‐alkyl L‐glutamates, including those higher than ethyl, and consequently, various poly(γ‐alkyl L‐glutamates) such as methyl, ethyl, n‐propyl, n‐butyl, isobutyl, and isoamyl. The conformation of these poly‐L‐glutamates in the solid state was determined by the infrared absorption method. The molecular motions of the polymers of γ‐methyl, ‐ethyl, ‐n‐propyl, ‐n‐butyl, and‐isoamyl L‐glutamates and poly(γ‐methyl‐D‐glutamate) in the solid state were studied by NMR, and dielectric and mechanical measurements. At temperatures up to 400°K., the NMR spectra of poly(γ‐methyl D‐glutamate) can be explained only by rotational motion of the side chain. Also, from NMR results, rotational motion of CO groups in the side chain of poly(γ‐methyl D‐glutamate) is expected near room temperature, and such a motion was examined by dielectric measurements. Rotation of CO groups in the side chains of polymers of γ‐methyl, γ‐ethyl, γ‐n‐propyl, γ‐n‐butyl, and γ‐isoamyl L‐glutamate was also observed near room temperature by dielectric measurements in the frequency range from 102 to 106 cps. Activation energies obtained by dielectric and mechanical measurements were similar to those for the side chain motions of the corresponding esters of poly(methacrylic acid). Although it has been noted that the molecular motion of poly(γ‐benzyl L‐glutamate) in the solid state at room temperature may be related to the motion of its back bone, the molecular motion in these poly‐L‐glutamates at these temperatures can be explained only in terms of side‐chain rotation.
Dependence of the glass transition temperature of poly(methyl methacrylate) on tacticity and molecular weight
Authors: Thompson Edward V. 
Published: April 2003

AbstractThe preparation of five samples of poly(methyl methacrylate) covering a wide range of tacticity and their electron irradiation to produce series of varying molecular weight are described. The glass transition temperature Tg of each polymer was determined by DTA techniques. Plots of Tg and the reciprocal of the molecular weight are well fitted in every case by a straight line. The data are also fitted to the Gibbs‐DiMarzio theory and the values of the energy and free‐volume parameters obtained are discussed. A method of estimating Tg of pure syndiotactic poly(methyl methacrylate) by extrapolation is presented, the value obtained being 160°C.
Formation of spherulites in polyamide melts: Part III. Even‐even polyamides
Authors: Magill J. H. 
Published: April 2003

AbstractA preliminary study of the isothermal crystallization of “even‐even” polyamides reveals striking similarities in spherulitic morphology. The observed variations in textural features of spherulites of nylon 210, nylon 66, nylon 610, and nylon 1010 show parallel changes during growth conditions and conform to a definite sequence of behavior. At least four different types of spherulites exist in each polymer. Optical and x‐ray techniques were used to examine some of these spherulites. Crystalline platelets possessing single‐crystal properties have been grown in thin films of these polymers near their respective melting points.
Polymer deformation. XI. Biaxial deformation of polyethylene single crystals
Authors: Haas K. , Geil P. H. 
Published: April 2003

AbstractUniaxial deformation of polyethylene single crystals has been reported in the previous papers of this series. This paper presents an extension of this study to the simultaneous biaxial deformation of polyethylene single crystals. Diamond‐shaped crystals containing {110} fold domains and truncated crystals containing in addition {100} domains were used in these experiments. The results show that these crystals fail at deformations as low as 6%, giving rise to cracks predominantly in the a direction. Electron diffraction patterns suggest that {310} twinning is more favorable than {110} twinning at the lower degrees of deformation. No phase change from orthorhombic to monoclinic unit cell is observed.
Mechanism of fracture in glassy polymers. IV. Temperature rise at the tip of propagating crack in poly(methyl methacrylate)
Authors: Kambour R. P. , Barker R. E. 
Published: April 2003

AbstractThe temperature rise at the moving crack tip in poly(methyl methacrylate), resulting from the dissipation of the energy of crack propagation has been calculated. At velocities below 1 cm./sec., conduction of heat away from the crack plane into the bulk polymer appears to prevent any appreciable temperature increase.
Polymer studies by gel permeation chromatography
Authors: Smith William B. , May James A. , Kim Chong W. 
Published: April 2003

AbstractSamples of polystyrene and poly(methyl methacrylate) have been prepared by bulk polymerization under conditions previously investigated in the literature. The molecular weight distributions were determined for early‐conversion samples by gel permeation chromatography, and the experimental distribution curves were compared with calculated curves based on kinetic data. The agreement between the experimental and calculated curves was such as to indicate the utility of gel permeation chromatography in the investigation of polymer reaction kinetics and mechanisms.
Wideline NMR studies of oriented nylon 66 under tensile stress
Authors: McMahon P. E. 
Published: April 2003

AbstractNMR linewidth studies of nylon 66 as a function of temperature and applied tensile stress have been conducted. The principal motional transition temperature was found to be shifted to higher temperatures with stress application by 9°C./g./den. At any given temperature, increased stress resulted in an increased linewidth. An attempt was made to correlate the shift in the motional transition temperature with the concept that a segment experiencing motion must do work against the applied tensile stress.
Phase relationships and thermodynamic interactions in linear polyethylene–diluent systems
Authors: Nakajima Akio , Fujiwara Hiroshi , Hamada Fumiyuki 
Published: April 2003

AbstractPhase equilibria between linear polyethylene and a number of organic diluents of varying type have been investigated. The diluents include aliphatic alcohols, alkyl phenols, aryl phenols, diphenyl derivatives, alkyl aryl ethers, esters, and ketones. It is found that n‐octyl alcohol, n‐decyl alcohol, n‐lauryl alcohol, p‐tert‐amyl alcohol, p‐octyl phenol, p‐nonyl, phenol, diphenyl, diphenylmethane, diphenyl ether, benzyl phenyl ether, and anisole are Θ‐solvents for linear polyethylene at temperatures between 120 and 200°C. Thermodynamic interactions are discussed in relation to the type of diluent.
Effect of chemical reagents on the fine structure of cellulose. Part III. Action of caustic soda on cotton and ramie
Authors: Warwicker J. O. 
Published: April 2003

AbstractThe changes in x‐ray orientation brought about by the treatment of cotton and ramie with caustic soda of different concentrations have been studied. With ramie the effect of the treatment is to decrease the x‐ray orientation, while with cotton the reverse is true. The cause of this difference is traced to a difference in the morphology of the two fibers rather than a difference in their fine structure.
Crystallization in poly(n‐octadecyl methacrylate) monolayers
Authors: Nakahara Tatsuo , Motomura Kinsi , Matuura Ryohei 
Published: April 2003

AbstractThe crystallization kinetics of poly(n‐octadecyl methacrylate) has been studied at the air–water interface. The rate of the crystallization has been measured by the decrease in the area of monolayers with time at various temperatures and surface pressures. The crystallization isotherms have been analyzed by the general mathematical treatment of the kinetics of phase changes, and the results show linear growth to be dominant. The variation of the rate constant with temperature and pressure has been illustrated by the difference in the supersaturation defined by introducing the equilibrium pressure‐area isotherms.
Les polyélectrolytes à l'interface liquide–liquide
Authors: Jaffe J. , Ruysschaert J.‐M. , Bricman G. 
Published: April 2003

AbstractThe behavior of films of polyelectrolytes at the water‐organic liquid interface depends on the nature of the interface and the pH of the substratum. The present paper investigates the influence of these two factors on the cohesive forces between monomer units. Two polyelectrolytes were studied: poly(methacrylic acid) (APM) and poly‐2‐vinylpyridine (2‐PVP). In the case of uncharged films, the collapse pressure decreases when the polarity of the organic phase becomes more important, whereas the term ω/kT, which appears in the theory of Motomura and Matuura, increases. A quantitative relation between the parameter ω/kT and the collapse pressure may be deduced. The behavior of the ionized surface film at different pH values is modified by the choice of the interface. However, there exists a competition between two phenomena: the dissolution of ionized residues in the substratum and the electrostatic repulsion between charges in the surface plane. Depending upon whether the first or the second parameter is more important, we observed that the surface pressure decreased or increased with the degree of ionization.
Glass transitions in ionic polymers
Authors: Eisenberg A. , Farb H. , Cool L. G. 
Published: April 2003

AbstractThe glass transitions of an ionic polymer in bulk have been studied as a function of the counterion for various homo‐ and copolymers. It is shown that the glass transition temperature can vary by as much as 530°C., from −10°C. for the nonionic material to +520 for Ca2+ or Zn2+ substituted polymer. From simple electrostatic considerations, it is shown that a linear correlation should exist beween the glass transition and the ratio of the cation charge, q, to the internuclear distance, a, between cation and chain anion; for this particular material (the polyphosphate chain) the relation is Tg = 625(q/a) −12 where q is in units of one electron and a is in A. If the data are interpreted in the light of the Gibbs‐DiMarzio theory, it is seen that both the chain stiffness and the intermolecular energy increase in an approximately parallel manner as q/a increases.
Angular distribution of intensity of rayleigh scattering from comblike branched molecules
Authors: Casassa Edward F. , Berry Guy C. 
Published: April 2003

AbstractThe angular distribution function P(θ) for intensity of light scattered by a dilute solution of comblike branched molecules has been determined for three situations of some interest for evaluation of experimental data: (1) the molecules are identical with branches of equal length attached equidistantly along linear backbone chains; (2) the molecules are homogeneous in mass, with the same number of branches on each molecule, but the branches are distributed at random along the chain; (3) branches and main chains are still uniform, but the molecules are heterogeneous in mass with the number of branches per molecule distributed according to the binomial distribution and the branches in any molecule spaced randomly along the backbone. Examination of numerical results shows that the scattering functions for models (1) and (2) are not very different. The function for case (3) is somewhat different from the others when the mean number of branches per molecule is small but they contain a large fraction of the mass of the molecule. Over a limited range of the pertinent variables (corresponding roughly to observations on typical vinyl polymers of molecular weights up to 106) all three functions agree quite well with P(θ) for homogeneous linear chains with the same mean‐square radius of gyration.
Viscoelasticity of crosslinked epoxy polymer in the transition region
Authors: Kwei T. K. 
Published: April 2003

AbstractThe dynamic mechanical properties of highly crosslinked epoxyamine polymer networks with nonrandomly distributed crosslinks were investigated. The transition temperatures of these polymers can be correlated with the number of CH2 groups between crosslink junctions in the aliphatic amine portions of the network. The steepness of the modulus‐temperature curve is also a function of crosslink density. This is in contrast with the case of natural rubber crosslinked by sulfur or by electron irradiation, where the modulus‐temperature curves have similar shapes although the glass transition temperature increases with the degree of crosslinking. An empirical distribution function, similar to the one used by Tobolsky for stress relaxation distributions, was used to describe the temperature dispersion of the dynamic moduli. Two parameters, hg and hr, are used to characterize the steepness of the dispersion curve below and above the transition temperature, respectively. It is tentatively concluded that hg correlates with the length of the CH2 sequences in the amine portion of the polymer. The quantity hr may be related perhaps to the motion involving the trifunctional nitrogen junction.
Etching of irradiated polyethylene with fuming nitric acid
Authors: Salovey R. , Hellman M. Y. , Matreyek W. , Winslow F. H. 
Published: April 2003

AbstractPreirradiation produced no detectable change in the molecular weight of solution‐ or melt‐crystallized polyethylene etched by fuming nitric acid. This is consistent with crosslinking in areas which are selectively eroded by nitric acid.
Boundary effect on the thermal degradation of copolymers
Authors: Shibasaki Yoshio 
Published: April 2003

AbstractThe mechanism of thermal degradation of vinyl‐type copolymers at high temperatures was investigated theoretically and experimentally. A parameter β was proposed to account for the boundary effect. Values of β for acrylonitrile–styrene and methyl methacrylate–styrene copolymers were determined experimentally. It was ascertained that the value of β was independent of the distribution of monomer sequence lengths in a copolymer, but dependent on the pyrolysis temperature and on the nature of the copolymer. The boundary effect is attributed to differences in the dissociation energies of CC bonds connecting terminal monomer units to adjacent monomer units in copolymer chain radicals.
Complex formation between catalysts, alcohols, and isocyanates in the preparation of urethanes
Authors: Frisch K. C. , Reegen S. L. , Floutz W. V. , Oliver J. P. 
Published: April 2003

AbstractThe mechanism of the catalyzed reaction between alcohols and isocyanates was investigated by means of NMR, infrared, and ultraviolet spectroscopy. The shift of the OH proton resonance in the NMR spectra indicated the existence of a 1 : 1 complex in the system dibutyltin dilaurate (DBTDL)–1‐methoxy‐2‐propanol. Complex formation was also observed when lead naphthenate or triethylamine (TEA) were substituted for the DBTDL. Mixtures of the DBTDL–TEA catalysts caused a shift of the OH proton resonance greater than that observed for either catalyst alone. This correlates with the synergistic effect noted when preparing urethanes with a mixture of these catalysts. No direct evidence of alcohol–catalyst complex formation could be obtained by infrared spectroscopy. Efforts were also made to detect complex formation in mixtures of phenyl isocyanate and catalysts. These complexes could not be detected by NMR, infrared, or ultraviolet spectroscopy.
Rates of polymer formation and monomer consumption in the solution polymerization of trioxane catalyzed by BF3 · O(C2H5)2
Authors: Miki T. , Higashimura T. , Okamura S. 
Published: April 2003

AbstractIn the solution polymerization of trioxane catalyzed by BF3 · O(C2H5)2 at 30°C. the amount of the methanol‐insoluble polyoxymethylene is less than the amount of monomer consumed. This difference was much larger than the amount of formaldehyde determined in the polymerized system and could not also be explained in terms of the amount of the methanol‐soluble oligomer. Tetraoxane was detected in large quantities by gas chromatography in the polymerized solution of trioxane. Therefore, the difference between the amounts of the methanol‐insoluble polymer and the monomer consumed was ascribed partly to the formation of tetraoxane. In spite of the fact that tetraoxane was polymerized more easily than trioxane by BF3 · O(C2H5)2, an almost constant amount of tetraoxane was produced, independent of the kind of solvent and the polymer yield. This suggests the existence of an equilibrium concentration of tetraoxane. On the other hand, the formation of trioxane was observed in the solution polymerization of tetraoxane by BF3 · O(C2H5)2. This suggests that the formation of tetraoxane during the trioxane polymerization is due to a back‐biting reaction in which the growing chain end of trioxane attacks the oxygen atom in its own chain with depolymerization of tetraoxane.
Copolymerization of the cyclic monomer, 5,5‐dichloro‐4‐hydroxy‐2,4‐pentadienoic acid lactone
Authors: Winston Anthony , Li George T. C. 
Published: April 2003

AbstractThe copolymerization of 5,5‐dichloro‐4‐hydroxy‐2,4‐pentadienoic acid lactone with methyl methacrylate, methyl acrylate, vinyl acetate, and vinylidene chloride to give yellow to red copolymers is described. Infrared, nuclear magnetic resonance, and ultraviolet spectroscopy indicate that the polymerization of the lactone proceeds by a 1,4‐addition mechanism, followed by hydrogen chloride elimination, to give a highly conjugated structural unit closely related to the structure of the original monomer. The intense colors of the copolymers may arise from conjugated sequences of lactone units or through further eliminations along comonomer sequences.
Detection and incorporation of amino endgroups in free‐radical polymerization of methyl methacrylate
Authors: Maiti Sukumar , Saha Mihir K. 
Published: April 2003

AbstractAmino endgroups have been incorporated in poly(methyl methacrylate) by two methods: (a) initiation with systems producing amine radicals and (b) chain transfer with amines. A new dye‐partition technique with the use of disulfine blue was developed for qualitative and in some cases quantitative estimation of amino endgroups in the polymer.