bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrolytic formation and destruction of living anions
Authors: Funt B. L. , Bhadani S. N. , Richardson D.
Published: April 2003

Electrolysis of solutions of α‐methylstyrene in THF resulted in the formation of the characteristic spectra of the living anions in the cathode compartment. The increase in absorbance of the solution was strictly proportional to the charge transferred at the electrode, and was independent of the electrolyte for NaAl(C2H5)4, NaB(C6H5)4, and KB(C6H5)4. For solutions of LiB(C6H5)4 the color decreased spontaneously on standing, and a linear relationship between absorbance and charge transferred was not obtained. Mixing of the anode and cathode solutions resulted in a destruction of the living ends and a disappearance of the color, which could be regenerated by further electrolysis. Reversal of the polarity of the electrodes produced a stoichiometric destruction of the living ends and a decrease in absorbance directly dependent on the charge transferred. The exact stoichiometric dependence furnished means of estimating impurity levels, living anion concentrations, and optical extinction coefficients based on the number of faradays passed through the solution. The control of molecular weight distribution and rate of reaction by these methods is indicated.
Study of Hydrocarbon‐Soluble Organometallic Catalysts. III. Investigations on the Activity and Electric Conductivity of Al(C2H5)3—M(C5H7O2)n Catalysts Employed in the Synthesis of Stereoregular Polyacetylene
Authors: Nicolescu I. V. , Angelescu Em.
Published: April 2003

The aim of the present work is to establish some correlations between the catalytic activity of several organometallic hydrocarbon‐soluble complex systems and the electric conductivity, as a method which expresses the ionization degree of these catalyst types. The following systems were studied: Al(C2H5)3—VO(C5H7O2)2; Al(C2H5)3—Cr(C5H7O2)3, Al(C2H5)3—Co(C5H7O2)3. The catalytic activity was determined at various molar ratios of AlEt3/M(C5H7O2)n in the stereoregular polymerization reaction of acetylene, where M is a metal. The visible and ultraviolet absorption spectra of the catalysts, as well as the variation of extinctions at various AlEt3/M(C5H7O2)n molar ratios were also determined. The systems with an optimal catalytic activity also show maximum values of electric conductivity and extinctions. The composition, degree of ionization of the catalyst, and the way in which this influences the catalytic activity are also discussed.
Aminobutadienes. VI. Polymerization and Copolymerization of 2‐Phthalimido‐1,3‐butadiene
Authors: Murata Kenichi , Terada Akira
Published: April 2003

2‐Phthalimido‐1,3‐butadiene (2‐PB) was polymerized either radically or thermally in bulk and in solution. While the polymer obtained by solution polymerization was soluble in some solvents such as halogenated hydrocarbons, dioxane, and dimethylformamide and had a softening point in the range of 160–170°C., that obtained by polymerization in bulk was insoluble in any solvent and only swollen on being immersed in such solvents as above. The reduced viscosity of the soluble polymer obtained by solution polymerization was approximately 1.0, and this value remained almost unchanged with varying polymerization time. Likewise the cationic polymerization in acetylene tetrachloride or in chloroform at 20°C. with the use of cationic catalysts such as boron trifluoride and stannic chloride was attempted, but no formation of polymer was observed. This monomer preferentially reacted with acrylonitrile, methyl methacrylate, styrene, and N‐vinylphthalimide to form the respective copolymers; it reacted somewhat less readily with vinyl acetate. The monomer reactivity ratios in the copolymerization with styrene were calculated by the Fineman and Ross method and found to be r1 (2‐PB) = 5.2 and r2 (styrene) = 0.11, respectively, from which the Q, e parameters were successively evaluated to be Q = 5.0 and e = −0.05. The fact that e value is close to zero, easily explains why this monomer can copolymerize well both with acrylonitrile, which has a highly positive value of e (1.2) and with styrene, for which e is considerably negative (‐0.8).
Monomer‐Polymer Equilibria of Deuterated α‐Methylstyrenes
Authors: Fetters Lewis J. , Pummer Walter J. , Wall Leo A.
Published: April 2003

The equilibria between α‐trideuteromethyl‐β,β‐dideuterostyrene, α‐methyl‐2,3,4,5,6‐pentadeuterostyrene, and perdeutero‐α‐methylstyrene and their respective polymeric anions in tetrahydrofuran have been investigated between 253 and 308°K. The heat and entropy changes were both increased by deuteration of the alkyl group. Qualitatively the effect observed appears best explained by the premise that a lowering of steric repulsions occurs with deuterium and hence the effective volume for deuterium is less than that for hydrogen.
Aromatic Polyamides of 2,6‐Naphthalenedicarboxylic Acid
Authors: Starr L.
Published: April 2003

Wholly aromatic polyamides have been prepared by the interfacial polycondensation of 2,6‐naphthalenedicarboxylic acid chloride with m‐phenylenediamine. Also, copolyamides with isophthaloyl or terephthaloyl chlorides and the naphthalene diacid chloride were synthesized. The resultant polyamides were amorphous or slightly crystalline as determined by x‐ray diffraction, had tensile properties characteristic of hard, strong materials, and were more thermally stable than aromatic polyamides prepared solely from benzene diacid chlorides.
How Ticl3 Catalysts Control the Texture of As‐Polymerized Polypropylene
Authors: Hock Charles W.
Published: April 2003

Within 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

Copolymers 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

The 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

The 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

Good 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

The 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

A 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

Uniaxial 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

The 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

Samples 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

NMR 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

Phase 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

The 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

The 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

The 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

The 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

The 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

The 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

Preirradiation 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

The 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

The 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

In 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

The 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

Amino 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.
Copolymerization of trioxane by γ‐radiation
Authors: Rösinger S. , Hermann H. , Weissermel K.
Published: April 2003

High molecular copolymers of trioxane with different cyclic ethers and formals were produced by γ‐radiation from a 60Co source. It was polymerized in the solid state at 53°C. Polymerization does not occur in the melt. Irradiation was carried out with exclusion of air at a dose rate of 7 × 103 rad/hr. The polymerization rate was increased very considerably in the presence of 1,3‐dioxolane and epichlorhydrin; the addition of other comonomers may reduce the yield. The concentration of the comonomer is generally higher in the polymer than in the initial mix. These comonomers which increase the polymerization rate are introduced preferentially into the polymer chain; this is proved by the unstable polymer part and the thermal stability. Experiments with the trioxane–1,3‐dioxolane system revealed that the unstable polymer part is markedly reduced and the heat stability considerably inproved with rising concentrations of this monomer. The thermal stability and the reduced viscosity of these copolymers are within the range of technical processability.
Polymerization with heterogeneous metalorganic catalysts. VI. Differences in polymerization activity of α‐olefins and some kinetic results on butene‐1 polymerization
Authors: Schnecko H. , Lintz W. , Kern W.
Published: April 2003

Relative changes in polymerization activity of ethylene, propylene, and butene‐1 in Ziegler‐Natta polymerization were compared by use of TiCl3 samples contaminated with O2 and H2O to various extents. Catalyst depletion varied for the three monomers which supported the existence of different active centers. In butene‐1 polymerizations with the system Al(C2H5)2Cl–TiCl3, the formation of active centers involves an irreversible and a reversible (adsorption) reaction, the former pertaining to the formation of Al(C2H5)Cl2 and dependent upon the purity of the TiCl3. The kinetic treatment of the rate curves suggests a mixed order of catalyst deactivation and again points to the importance of Al(C2H5)Cl2.
Course of the terpolymerization of ethylene, propylene, and dicyclopentadiene. I. Single initial addition of dicyclopentadiene
Authors: Cunningham Robert E.
Published: April 2003

Detailed studies were made of the course of the terpolymerization of ethylene, propylene, and dicyclopentadiene to form unsaturated elastomers. All the dicyclopentadiene was added at the start of a polymerization, but the monoolefins were added continuously throughout the run. Under these conditions, unsaturation of the initial polymer is fairly high but decreases steadily as the reaction progresses. From analyses of the initial samples from each run, the catalyst of VCl4 (with Al2Et3Cl3 cocatalyst), with heptane as the polymerization solvent, was most efficient for introducing unsaturation into terpolymer. This system also produces gel in the terpolymer in the latter stages of reaction, however. Catalysts of VCl4, VOCl3, or V(C5H7O2)3, with Al2Et3Cl3 cocatalyst, in benzene solvent gave terpolymers of quite similar unsaturations. With all systems, terpolymer yield increases very rapidly in the first few minutes of reaction, then very slowly for the remainder of the 30‐min. reaction time, reflecting the rapid loss of activity of the vanadium catalysts. Molecular weight growth of the terpolymer prepared in heptane was extremely rapid, reaching a high value in a few minutes. When prepared in benzene, the terpolymers showed a steady increase in molecular weight throughout the reaction but reached only a moderate final value (as expressed by inherent viscosity).
Preparation and polymerization of some vinyl monomers containing the 2‐oxo‐1,3‐dioxolane group
Authors: D'Alelio G. F. , Huemmer T.
Published: April 2003

The syntheses and polymerizations of (2‐oxo‐1,3‐dioxolan‐4‐yl)methyl acrylate, 4‐(2‐oxo‐1,3‐dioxolan‐4‐yl)methyl itaconate, and (2‐oxo‐1,3‐dioxolan‐4‐yl)methyl maleate are described. Reactivity ratios in the copolymerization of these monomers with other comonomers are reported and the Alfrey‐PriceQandevalues calculated. The post‐polymerization effects of ultraviolet light and heat on these polymers and copolymers are presented and compared to those for similar polymers containing the 2,2‐dimethyl‐1,3‐dixolane groups, which performs as an internal ultraviolet sensitizer. The 2‐oxo derivatives are crosslinked thermally but not by ultraviolet light. The crosslinking reaction can be catalyzed by acids, bases, and salts.
Structural effects in heteroatom systems. II. The calculated influence of steric effects on polymerization–depolymerization equilibria in the siloxane and oxymethylene series. Comparisons with the phosphazene system.
Authors: Allcock H. R.
Published: April 2003

The relative stabilities of symmetrically substituted polysiloxanes and polyoxymethylenes are compared in terms of the side‐group steric overlap parameters, by means of a semiempirical method described previously. The results provide a qualitative estimate of the relative thermodynamic ease of polymerization of cyclic siloxanes or monomeric methylene oxides or, conversely, of the relative resistance to depolymerization of the polymers. These calculated values are compared with those reported previously for phosphazenes. In general, for polymers of the type, [R2SiO]n, [R2CO]n, and [R2PN]n, if the side group, R, is small (H, halogen or methyl) the inherent steric and bonding characteristics of the chain should cause the polymer stabilities to decrease in the order phosphazenes ≈ siloxanes ≫ oxymethylenes. If, however, bulkier side groups are present, the order of decreasing stability to depolymerization should be siloxanes > phosphazenes ≫ oxymethylenes. In all cases, the depolymerization tendency should increase markedly as the side group overlap parameters increase, and polyoxymethylenes should be the most sensitive to such changes. The calculated results are compared with the limited experimental evidence at present available.
Head‐to‐head units in poly(propylene oxide) by ozonation
Authors: Price Charles C. , Spector Robert , Tumolo Anthony L.
Published: April 2003

By extensive ozonation and lithium aluminum hydride reduction, poly(propylene oxide) can be converted to material containing dipropylene glycol. Since the diprimary, disecondary, and primary‐secondary isomers are readily separable by vapor‐phase chromatography, it has been possible to show that some (but not all) noncrystalline PPO samples contain many head‐to‐head, tail‐to‐tail monomer units. Correlation of the fraction of head‐to‐head units with the optical rotation of noncrystalline fractions from optically active monomer, indicates that there is one asymmetric center inverted for every unit inserted head‐to‐head. The earlier suggestion that the noncrystalline fraction was due to atactic stereochemistry is thus shown to be generally incorrect in favor of an explanation due to positional isomerization.
Ionic polymerization of p‐vinylbenzyl methyl ether
Authors: Symcox Robert O. , Cotman John D.
Published: April 2003

Ionic polymerizations of vinylbenzyl methyl ether initiated by either carbanions or Lewis acids has been found to lead to crosslinked polymers. By comparative studies of strong carbanionic bases and Lewis acids with benzyl ethers, it has been possible to define details of mechanisms which in conjunction with cationic or anionic propagation lead to crosslinks. The α‐hydrogens of benzyl ethers have been found to be sufficiently acidic to terminate anionic polymerization of styrene and displacement of alkoxide anion from the benzyl ether linkage by nucelophilic polymer anions is proposed as a mechanism leading to branching and eventual crosslinking in anionic polymerization of vinylbenzyl methyl ether. Cationic polymerization of vinylbenzyl methyl ether is quite complex. In addition to propagation, chain transfer, and spontaneous termination of cation chain carriers, there is evidence for complex formation between Lewis acid initiator and the benzyl ether substituent. A slow decomposition of ether–Lewis acid complexes produces benzylcarbonium ions which alkylate aromatic rings of polymer and thereby crosslink the polymer. Benzyl ether has been found to be an effective chain terminator for cationic styrene polymerization.
Graft copolymerizations of gaseous vinyl chloride and vinylidene chloride on preirradiated polypropylene
Authors: Hayakawa Kiyoshi , Kawase Kaoru
Published: April 2003

The graft copolymerizations onto the preirradiated polypropylene fibers of gaseous vinyl chloride and also of gaseous vinylidene chloride were carried out. The fibers were preirradiated with γ‐rays from a 60Co source at −78°C. in air to a total dose of 8 X 105 rad, and were thus presumed to contain peroxide radicals which were active in grafting at ordinary temperature. The volume decrease of monomers at constant pressures due to the sorption and the grafting reaction was followed automatically at temperatures ranging from −10 to 80°C. The net monomer consumption through the grafting process was estimated by subtracting the volume change due to the sorption from the total volume change of monomers. In general, the extent of grafting was lower at the higher grafting temperature and the decrease of the grafting activity of fibers was also accelerated. The grafting was found to increase almost linearly with the logarithm of the reaction time and the logarithm of the radiation of the radiation dose to the fibers. The extent of grafting was also proportional to the vapor pressure of monomer at a given reaction temperature and was supposed to be controlled by the amount of the monomer adsorbed. Raising the irradiation temperature higher than 0°C. brought about a marked decrease in the activity of preirradiated polypropylene. The grafting activity was successfully retained by the polymer for at least a fortnight at −78°C.
Emulsion polymerization of acrylonitrile. Part I. Role and effect of emulsifiers in the emulsion polymerization of acrylonitrile
Authors: Izumi Zenzi , Kiuchi Hiroshi , Watanabe Masamoto
Published: April 2003

The role in and effects on the emulsion polymerization of acrylonitrile (AN) of three different groups of emulsifiers, i.e., low molecular emulsfiers, well‐known water‐soluble polymers, and new water‐soluble polymers containing a sulfonate group have been investigated by a dilatometry and electron microscopy. The major part of this paper concentrates on the study of the relation between the properties of the third group of emulsifiers and emulsion polymerization characteristics of AN such as rate, degree of polymerization, diameter and number of particles, and the degree of dispersion, by adding copolymers of AN and sodium p‐styrenesulfonate (SSS) having various compositions. In the emulsion polymerization of AN, the hydrophobic portion of the emulsifier seems to act as a kind of nucleus around which polymer molecules precipitate and particle formation may occur, and the hydrophilic portion stabilizes the polymer particles thus formed. As the number of particles and the degree of dispersion increases, the total surface of the particles increases, which may raise the overall rate of polymerization due mainly to an increased polymerization on the surface of the polymer particles. The well‐known emulsifiers may be classified by the properties and ratio of the nucleus portion and the stabilizing portion. The unusual effect of emulsifiers on the degree of polymerization may be explained by a chain‐transfer mechanism.
Mechanism of stereoregular polymerization of butadiene by homogeneous Ziegler‐Natta catalysts. I. Effects of the species of transition metals
Authors: Matsuzaki Kei , Yasukawa Tamio
Published: April 2003

Butadiene was polymerized by catalysts of the type: metal acetylacetonate (metal: Ti to Ni in the periodic table)–triethylaluminum–aluminum halide, with various ratios of triethylaluminum to aluminum halide. The minimum cis content was observed with vanadium catalyst in all cases, while the minimum polymer yields were observed with the iron and the manganese catalysts. These transition metal effects are discussed in terms of the crystal field theory, and it is suggested that the electrostatic interaction between the nearly nonbonding electrons of transition metal atom and a butadiene molecule or a growing end of the polymeric chain plays an important role in the stereoregular polymerization of butadiene by homogeneous Ziegler‐Natta catalysts.
Mechanism of stereoregular polymerization of butadiene by homogeneous Ziegler‐Natta catalysts. II. Effects of the nature of bases and halogens
Authors: Matsuzaki Kei , Yasukawa Tamio
Published: April 2003

The effects of the addition of various bases to metal acetylacetonate–diethylaluminum chloride catalyst systems were investigated. Generally speaking, the cis content of polybutadiene decreases as the basicity of bases in a homologous series increases. The effects were more prominent for the cobalt and the titanium catalysts than for the nickel and the vanadium catalysts. The effects of the species of halogens on the microstructure of polybutadiene were also discussed. In conclusion, the decrease of the cis content was ascribed to the decrease of the electron density of dπ orbitals of the transition metal atoms.
Polymers with quinoxaline units. II
Authors: De Schryver Frans , Marvel C. S.
Published: April 2003

A double chain or ladder polymer was obtained by the condensation of 1,2,4,5‐tetraaminobenzene with 2,3,7,8‐tetrasubstituted‐1,4,6,9‐tetraazaanthracene and self‐condensation of 2,3‐dihydroxy‐6,7‐diaminoquinoxaline and of 2,3‐diphenoxy‐6,7‐diaminoquinoxaline. The polycondensations were carried out in solution or in melt. The polymers thus obtained were highly colored products which had inherent viscosities up to 2.5. The structures of the polymers were established by comparison with model compounds.
Polymerization of gaseous diazomethane on silicone grease
Authors: Kubota H. , Morawetz H.
Published: April 2003

Dow Corning high vacuum silicone grease is a powerful catalyst for the polymerization of gaseous diazomethane. The catalytic activity is due to boric ester groups incorporated in the polysiloxane contained in the grease. The polymerization rate is proportional to the area of the interface but independent of the thickness of the grease layer, indicating that only a surface layer is involved in the catalytic action. The chain length of the polymethylene formed does not depend on the area of the interface or the pressure of the gaseous monomer. The dependence of the polymerization rate and polymer chain length on temperature is analogous to that for similar processes in homogeneous solution.
Molecular parameters of sodium cellulose xanthate in dilute solution
Authors: Das Bibekananda , Choudhury P. K.
Published: April 2003

Molecular parameters of sodium cellulose xanthate in NaOH solution have been determined by means of light scattering and viscometry. The effect of the degree of substitution on the molecular configuration of sodium cellulose xanthate has been studied for three series of samples of varying degree of substitution. The expansion factor has been determined from the expression due to Orofino and Flory. The effective bond length b and the ratio of the unperturbed dimension to the dimension assuming free rotation of the chain units (R̄o2/R̄f2)1/2, have also been determined. It is concluded that sodium cellulose xanthate in dilute solution is a loosely coiled molecule, comparable to other cellulose derivatives in chain stiffness.
Kinetics of the γ‐radiation‐induced polymerization of methyl methacrylate in the solid state
Authors: Lipscomb N. Thornton , Weber Edwin C.
Published: April 2003

Studies have been made of the γ‐radiation‐induced polymerization of methyl methacrylate in bulk, in the solid state at a temperature of −65°C. and a radiation intensity of 346,000 rad/hr. The reaction was found to have an extremely long induction period (∼50 hr.) when pure monomer was used, and to be first‐order with respect to polymer concentration. This first‐order dependency was confirmed by a series of irradiations in which 0.6% poly(methyl methacrylate) was dissolved in the monomer before irradiation. These irradiations showed no induction period. Nuclear magnetic resonance spectroscopy indicated a much more heterotactic polymer than that obtained in the liquid state at −49°C.
Linear polymers of acrylic monomers containing an acetylenic moiety
Authors: D'Alelio G. F. , Evers R. C.
Published: April 2003

1‐Acryloxy‐2‐butyne and 1‐methacryloxy‐2‐butyne were synthesized and polymerized by means of anionic initiators to soluble linear polymers containing acetylenic bonds in the pendant side chains. In contrast, insoluble, crosslinked polymers were formed when cationic and radical initiators were used. The unpolymerized acetylenic bonds in the resulting linear polymers were shown to be present by infrared spectroscopic methods and by the following post‐reactions of these bonds: (1) the thermal‐ and radical‐initiated crosslinking of the linear polymers through the acetylenic bonds; (2) the post‐bromination of the acetylenic bonds; and (3) the reaction of decaborane with the acetylenic bonds. The anionic copolymerization of both monomers with a number of selected monomers was performed and the copolymer reactivity ratios for several of the comonomer pairs were determined. Dibromination of the linear polymers affords self‐extinguishing polymers with apparently good hydrolytic stability. Decarbonation of the linear polymers yields soluble polymers which do not soften up to 300°C. The linear polymers and copolymers, as well as their partially brominated and partially decaboronated products, may be classified as “self‐reactive” polymers which yield thermosetting polymers.
Studies on anionic polymerization of lactams. Part III. Copolymerization of pyrrolidone and caprolactam
Authors: Bar‐Zakay S. , Levy M. , Vofsi D.
Published: April 2003

On reacting acetylcaprolactam (AcCL) and pyrrolidonate MgBr (Py−) in tetrahydrofuran solution, transacetylation takes place, giving acetylpyrrolidone (AcPy) and caprolactamate MgBr (CL−). The rate constants for the transacetylation reactions were measured at 25°C. Their values in units of liters/mole‐second were:

The rate constants for the addition reactions measured were:

As the transacetylation is much faster than the addition reaction the copolymer composition should be given by the equation:

where Ktrans, the transacetylation equilibrium constant, equals 0.3 while Kacidity reflects the relative acidities of the monomers and its value (from the literature) is about 0.4. Pyrrolidone is, therefore, more reactive than caprolactam in anionic copolymerization by a factor of about 8.
Poly(chloroaldehydes). IV. Copolymerization of chloral and dichloroacetaldehyde catalyzed by organometallic compounds
Authors: McCain G. H. , Hudgin D. E. , Rosen Irving
Published: April 2003

The copolymerization of chloral and dichloroacetaldehyde (DCA) has been studied with the use of organometallic compounds as initiators. The alkylzincs were the most effective catalysts, giving good conversions to copolymers of apparently high molecular weight. The polymerizations were best carried out at temperatures below −40°C. at an initiator concentration of at least 0.4 mmole/mole of monomers. The copolymerization proceeds to high conversions in toluene as the solvent, but the presence of small amounts of either n‐heptane or tetrahydrofuran greatly decreases the yield. This, coupled with the fact that little polymerization occurs at DCA concentrations above 70 mole‐%, leads to the proposal of a propagation reaction mechanism involving the coordination of the monomeric aldehydes with a cyclic zinc alkoxide dimer. Monomer reactivity ratios with chloral as M1 and DCA as M2 were r1 = 1.50 and r2 = 0.65. The copolymer is stiff and inelastic with a tensile strength of ca. 6000 psi.