bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emulsion polymerization of styrene in coacervating and noncoacervating soap–electrolyte systems
Authors: Mateo J. L. , Cohen Irving 
Published: April 2003

AbstractAn attempt is made here to delineate some of the consequences of the special properties of coacervating soaps when the soaps are used in the emulsion polymerization of styrene. In dilute solutions an essential difference between a coacervating soap and a noncoacervating soap is the critical suppression of the micellar ionization in coacervating systems when relatively small amounts of simple electrolytes are added to the systems. A direct correlation between the polymerization rates and polymer molecular weights with the state of micellar ionization has been demonstrated. The highest polymerization rates and highest polymer molecular weights occur in solutions in which the coacervating soaps show a maximum ionization. In soap solutions in which the micellar ionization is critically suppressed there is evidence of soap desorption from polymer particles, resulting in the generation of an increasing number of particles during the course of the polymerization. Two coacervating systems and two noncoacervating systems were used in this investigation. For the anionic noncoacervating K laurate–KCl system, where the micellarsize remains practically constant with the addition of electrolyte, the following relationship between the polymerization rate and KCl concentration, up to 1M KCI, has been found: R = R0 + B√C. The effects of the charge properties of soap micelles on the course of the polymerization of styrene have been associated with two effects. (a) For highly ionized micellar systems the micelle periphery presents an open structure due to the coulombic repulsion of the charged polar hydrophilic groups of the soap molecules. This open structure facilitates the diffusion of monomer to the loci of polymerization. (b) Where the micellar ionization is suppressed, monomer diffusion to the loci of polymerization is impeded. Extensive suppression of micellar ionization results in micelles of enhanced stability. In the highly stabilized systems when the loci of polymerization are polymer particles there is competition for soap molecules between the adsorption sites on the polymer particle and soap micelles. The influence of soap concentration on the emulsion polymerization for different soaps and electrolyte concentrations has been investigated. For the coacervating Hyamine 1622 soap at zero electrolyte concentration, the rate of polymerization has been found to be proportional to the 0.5 power of the soap concentration. This relationship is not maintained when electrolyte is added to the polymerization system.
Rheological properties of polybutadienes prepared by n‐butyllithium initiation
Authors: Gruver J. T. , Kraus Gerard 
Published: April 2003

AbstractThe flow behavior of n‐butyllithium‐polymerized polybutadienes was investigated as a function of molecular weight, temperature, and shear rate. At low shear rates these polymers exhibit Newtonian flow up to molecular weights of several hundred thousand so that “zero shear” Newtonian viscosities can readily be determined without the risk of long extrapolation. Above 10,000 molecular weight the Newtonian viscosities obey the well‐known 3.4 power dependence on weight‐average molecular weight. The entanglement spacing molecular weight is estimated at 5600. The temperature dependence of viscosity is substantially independent of molecular weight and shear stress and can be represented analytically by functions proposed in the literature. The apparent activation energy for viscous flow is not constant, but decreases with rising temperature. The flow of the polymers becomes increasingly non‐Newtonian with the product of shear rate, molecular weight and Newtonian viscosity. However, the departure from Newtonian behavior is apparently less than for any polymer system whose flow behavior has been described in the literature. The indications are, therefore, that sharp molecular weight distribution and freedom from long chain branching favor Newtonian flow and that the n‐butyllithium initiated polybutadienes represent some of the most perfectly linear, narrow distribution polymers known.
Some reactions of p‐vinylacetophenone–styrene copolymers
Authors: Beckerbauer Richard , Baumgarten Henry E. 
Published: April 2003

AbstractA new synthesis of p‐vinylacetophenone was developed. Copolymers of p‐vinylacetophenone and styrene were prepared by copolymerization and by partial Friedel‐Crafts acetylation of polystyrene. The copolymers were converted into the oximes, but subsequent reduction was unsuccessful. Beckman rearrangement of the oximes led to insoluble resins. The acetyl copolymers were partially brominated to give an α‐bromo‐p‐vinylacetophenone/p‐vinylacetophenone/styrene terpolymers. Nucleophilic displacement of the bromine of these terpolymers with secondary amines yielded α‐piperidino‐ and α‐morpholino‐p‐vinylacetophenone terpolymers. The Delepine reaction of the brominated copolymer produced an α‐amino‐p‐vinylacetophenone terpolymer. The piperidino and amino ketone terpolymers were reduced to the corresponding alcohol derivatives with lithium‐aluminum hydride. The amino ketone and amino alcohol terpolymers had moderate solubility characteristics in acidic alcohols and water. The α‐amino ketone terpolymer was very sensitive to base and afforded a facile crosslinking of the acetyl copolymer.
Instrument for the studies of differential flow dichroism of polymer solutions
Authors: Wada Akiyoshi , Kozawa Shichibei 
Published: April 2003

AbstractA concentric cylinder apparatus for the studies of flow dichroism in polymer solutions is described in detail. The outer and inner cylinders are both made of fused quartz which is transparent in visible and ultraviolet region down to 220 mμ. The velocity gradient is produced in solution in the gap between the cylinders by rotating the inner one. The light path is designed to be perpendicular to the axis of rotation of the quartz cylinder. A differential device makes it possible to measure the difference in absorption coefficients, ε‖ and ε⊥, which are the absorption coefficients measured by plane‐polarized light having parallel and perpendicular electric vector with the stream line. The apparatus is found to be useful for studying the regularity of orientation of chromophores in both synthetic and biological polymer chains.
High resolution NMR study of vinylidene chloride–vinyl chloride copolymer
Authors: Chûjô Richiro , Satoh Shiroh , Nagai Eiichi 
Published: April 2003

AbstractThe presence of head‐to‐head structure in vinylidene chloride sequence in copolymer of vinylidene chloride and vinyl chloride with various feed ratios was demonstrated by the high resolution NMR study. The ratio of head‐to‐head structure in vinylidene chloride sequence was evaluated from measurement of the intensities of NMR spectra. The quantities of local regularity of copolymer were used in the theoretical treatment based on the virtual boundary energy and combinatory method. The experimental results were compared with the theoretical calculations.
Anisotropic elasticity of composite molecular networks formed from non‐gaussian chains
Authors: Smith K. J. , Ciferri A. , Hermans J. J. 
Published: April 2003

AbstractThe theory of composite networks by Berry, Scanlan, and Watson was generalized so as to include the case in which the elasticity of the chains is described by non‐Gaussian statistics. For this purpose, existing theories of non‐Gaussian networks had to be critically reviewed and a new simple treatment is presented here. This new treatment yields substantially the same results as that obtained from the more complex theory of Wang and Guth. Results obtained from the simple three‐chain model for the network, as described by Treloar, were also shown to be in satisfactory agreement with both the new treatment and that of Wang and Guth. The generalized theory of composite networks predicts anisotropic elastic behavior; the tensile force at a given strain should be generally higher for elongation in the direction parallel to orientation than in the direction perpendicular to it. However, depending upon details pertaining to the preparation of the networks (ratio of first and second stage crosslinks and elongation at which the latter are introduced), the tensile force required for elongation in the direction perpendicular to orientation may be higher. It appears that the isotropic elastic behavior, predicted by previous theories of composite networks, is merely a consequence of the use of the Gaussian approximation.
Aromatic polysulfonates: Preparation and properties
Authors: Thomson David W. , Ehlers Gerhard F. L. 
Published: April 2003

AbstractAromatic polysulfonates of high molecular weight and purity can easily be prepared by interfacial polycondensation of the disulfonyl chlorides with diphenols. The polymers were found to have a low degree of crystallinity, softening ranges in the region 200–250°C, molecular weights up to 50,000 and a thermal stability under nitrogen to above 300°C.
Free volumes in polystyrene and polyisobutylene
Authors: Miller A. A. 
Published: April 2003

AbstractThe melt viscosities of polystyrene and polyisobutylene fractions are expressed by a modified Arrhenius (M.A.) temperature equation, η = A exp {B/(T − T0)}, and by a free volume equation, η = A exp 1/{f}, in which f = vf/v, the free volume fraction. Thus, it is assumed that f, as defined, is a linear function of temperature, since f = (T − T0)/B. By this method, the derived “occupied” volume, vs = v −vf, has a temperature dependence which is determined by the temperature coefficients of f and v (i.e., 1/B and αl) and is not related to the experimental αg value for the glass. For polyisobutylene, the temperature coefficient of vs is positive, while for polystyrene it is slightly negative. Possible effects of liquid structure in determining the temperature behavior of vs are suggested. Calculated viscosities and free volume fractions at the glass point, Tg, over a wide range of molecular weight, M, in both polymers lead to the conclusion that the glass transition is primarily an “iso‐viscosity” (ηg ≃ 1013 poise), rather than an “iso‐free volume”, state. However, in the two polymers, both conditions can exist simultaneously for similar values of M. Thus at equal M,fg = (Tg = T0/B) is about the same for both polymers. For M ≃ 100,000, fg ≃ 0.031. These observations support the view that the glass transition is primarily a kinetic, rather than a thermodynamic, phenomenon. The estimated time dependence of Tg is found to differ in the two polymers at equal M and to vary with M in each case.
Multicomponent non‐fickian diffusion through inhomogeneous polymer membranes
Authors: Frisch H. L. 
Published: April 2003

AbstractWe point out explicitly the dependence of the non‐Fickian diffusive flows of low molecular weight penetrants through a polymer membrane possessing a gradient in internal composition or a local property, such as a stress, on the gradient of the chemical potential of the polymeric substance. The possibility of maintaining for sufficiently long times a gradient in internal composition or property in these substances is a consequence of the long relaxation times encountered in these substances. A number of ways are suggested for preparing such membranes. Certain consequences for the diffusive separation of penetrants by such membranes are noted.
Poly(1,3,4‐oxadiazoles): A new class of polymers by cyclodehydration of polyhydrazides
Authors: Frazer A. H. , Sweeny W. , Wallenberger F. T. 
Published: April 2003

AbstractThirteen aliphatic and aromatic polyhydrazides have been converted as bulk polymer by a unique polymer by a unique polymer post reaction into high molecular weight poly(1,3,4‐oxadiazoles). This reaction proceeds by thermal cyclodehydration at 170–280°C. with elimination of water. The resulting poly(1,3,4‐oxadiazoles) have been characterized by microanalysis, inherent viscosity, x‐ray diffraction patterns, and by infrared and ultraviolet absorption spectra. Films could be pressed from the melt of polyoxadiazoles melting below 350°C., while very high melting or infusible aromatic polyoxadiazoles could not be manufactures into films and fibers by conventional means. Such polymers are extremely thermally and oxidatively stable and decompose between 450 and 500°C.
Poly(1,3,4‐oxadiazolidine)
Authors: Frazer A. H. , Wallenberger F. T. 
Published: April 2003

AbstractPoly(3,4‐isophthaloyl‐1,3,4‐oxadiazolidine) was prepared from poly(isophthalic dihydrazide) by treatment by reaction with formic acid in dimethylsulfoxide as high‐molecular weight film‐forming polymer. Under thermal treatment with the evolution of formaldehyde and water, high yields of chemically pure poly[1,3‐phenylene‐2,5‐(1,3,4‐oxadiazole)] were obtained.
Molecular weight dependence of the second virial coefficient. Solutions of styrene dimers up to high polymers and other systems
Authors: Sotobayashi H. , Ueberreiter K. 
Published: April 2003

AbstractThe second virial coefficient B or A2 has been calculated from cryoscopic measurements in naphthalene of polymers of styrene from dimers up of high polymers. The B‐degree of polymerization curve has a maximum in the range of the tetramer. The portion of the curve showing the increase to a maximum is explained as a “macromolecule effect” of rigid rods according to the theory of Flory and Huggins. The A2–P (or B–P) curves investigated so far are described by the equation, A2 = (a/M1/2) + b. It is assumed that the shape of a macromolecular coil in solution depends upon the fact whether the main chain skeleton and its sidegroups have the same or opposite affinity to the solvent. In the case of polystyrene in naphthalene it is assumed that the CC chain behaves as a lyophobe and the benzene groups as a lyophil. This leads to an increased density of the benzene sidegroups in the surface of the macromolecular coil. The interaction potential between the coils as a whole is therefore different from that in the interior. This effect is realized by splitting the excluded volume into two parts and leads to the reciprocal square root dependence of A2. This equation has been tested for many endothermal and exothermal systems. The constants a and b are zero at the θ‐temperature and can be determined therefrom.
An elementary theory of nonlinear viscoelasticity
Authors: Davis Julian L. 
Published: April 2003

AbstractA first‐order, nonlinear, one‐dimensional theory of viscoelasticity is constructed by use of an elementary perturbation technique. It is based on applying some simple hypotheses of nonlinearity to single nonlinear Maxwell and Voigt models. The response of the Maxwell model to a sinusoidally applied strain is governed by a nonlinear complex modulus whose nonlinear part is given as a function of applied strain and strain rate as well as external frequency and internal or model parameters. This is a nonlinear relaxation effect. A nonlinear creep effect is obtained by describing the nonlinear response of the Voigt model to a sinusoidally applied stress in terms of a nonlinear complex compliance.
Polymerization studies on allylic compounds. Part II
Authors: Reed Samuel F. , Baldwin M. G. 
Published: April 2003

AbstractThe free radical polymerization of a series of compounds having the general formula
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in which Y was F, Cl, Br, I, NO2, and CN has been studied. The compounds were found to vary markedly in polymerizability. An explanation is advanced in which it is postulated that chain transfer involving a substituent in the allylic position of the monomers is the controlling factor in determining their polymerization behavior.
Determination of halogen in copolymers by dye‐partition technique and calculation of r1 therefrom
Authors: Saha Mihir Kumar , Ghosh Premamoy , Palit Santi R. 
Published: April 2003

AbstractHalogen‐bearing polymers have been prepared by copolymerization of monomers (M1) such as styrene, methyl methacrylate, methyl acrylate, and vinyl acetate with traces of chlorine‐bearing monomers (M2) such as allyl chloride and tetrachloroethylene at varying M1:M2 ratios in the 100:1 composition range. The halogen atoms in the copolymers were transformed to quaternary pyridinium halide groups by quaternization with pyridine. The copolymer compositions and the monomer reactivity ratio r1 were determined by the estimation of the quaternary halide groups in the copolymers by the dye‐partition technique, with aqueous disulfine blue VN150 in 0.01M hydrochloric acid as the dye reagent.
Branching in high conversion poly(methyl methacrylate)
Authors: Krause Sonja , Cohn‐Ginsberg Elizabeth 
Published: April 2003

AbstractThe dilute solution properties (intrinsic viscosity, weight‐average molecular weight, and mean square radius of gyration) of fractions of high conversion, free‐radically initiated poly(methyl methacrylate) samples indicate a slight amount of branching in these samples, consistent with the chain transfer constant with polymer (exclusive of endgroups), Cp = 2.2 ± 0.7 × 10−5, found by Schulz and co‐workers. The dilute solution properties of these fractions are compared with those of fractions of low conversion poly(methyl methacrylate) of comparable molecular weight and with the dilute solution properties of fractions of deliberately branched sample, also of comparable molecular weight. Some evidence was obtained which indicated that impurities in the monomer used for polymerization can lead to additional branching sites in the polymer chains.
Preparation of poly(arylene sulfides)
Authors: Tsunawaki Shigemitsu , Price Charles C. 
Published: April 2003

AbstractThe attempted polymerization of thiyl radicals from 4‐bromothiophenol (I), 2,6‐dimethyl‐4‐bromothiophenol (II), 2,6‐dimethylthiophenol, and bis(2,6‐dimethylphenyl) disulfide gave no polymer. The polymerization of lithium and sodium salts of I, II, and 2‐methyl‐4‐bromophenol and of sodium 4‐chlorothiophenoxide by refluxing in various solvents with or without copper catalyst, gave the corresponding poly(arylene sulfides). Poly(phenylene sulfide), m.p. 270–290°C. was stable at 500°C. for 2 hr. under nitrogen and showed high crystallinity by x‐ray. Poly(2,6‐dimethylphenylene sulfide), m.p. 160–180°C., showed little if any crystallinity by X‐ray diffraction. Poly(2‐methylphenylene sulfide) melted at 60–100°C.
Fractionation of chemically heterogeneous latex particles by centrifugation
Authors: Yannas J. B. 
Published: April 2003

AbstractA simple centrifugation method for the clean separation of chemically heterogeneous latex particles is described in some detail. It exploits density differences among particles that could be due to differences in composition, degree of crosslinking, crystallinity or other structural features. Particles differing in density by as little as 0.005 g./ml. have been cleanly separated. The fractionation of particles differing in density by less than the above should be feasible with this method which is applicable to concentrated as well as dilute latices.
α‐Trifluoromethyl vinyl acetate
Authors: Haas Howard C. , Schuler Norman W. 
Published: April 2003

Abstractα‐Trifluoromethyl vinyl acetate has been synthesized. Although the homopolymer has not been obtained, this new monomer readily copolymerizes with a variety of vinyl monomers including styrene. Alcoholysis of vinyl acetate/α‐trifluoromethyl vinyl acetate copolymers leads to trifluoromethyl‐substituted polyvinyl alcohols having new and unusual properties. These polyvinyl alcohol derivatives, containing about 30 wt.‐% of fluorine, are completely insoluble in water but dissolve in the lower alcohols. Because of the increased acidity of fluorosubstituted alcohols, they are also soluble in dilute aqueous alkalies to yield polyalkoxide‐type solutions.
Nitrogen adsorption isotherms on polyolefins
Authors: Hightower Joe W. , Emmett P. H. 
Published: April 2003

AbstractNitrogen adsorption isotherms were determined for a number of polyolefinic compounds. B.E.T. calculations showed that most of the samples possess surface areas averaging about 0.5 m.2/g., although a few very high molecular weight polyolefins precipitated during polymerization have areas of about 8 m.2/g. On most of the polyolefins, the C values from the B.E.T. equation are unusually small, indicating a relatively low heat of nitrogen adsorption. Adsorption isotherms were determined with krypton on two of the high polymers and were found to yield areas in satisfactory agreement with those obtained from the nitrogen adsorption experiments.
Effect of temperature on molecular weight measurements in polyethylene
Authors: Schreiber H. P. , Waldman M. H. 
Published: April 2003

AbstractLight‐scattering evaluations of molecular weight and gyration radii have been carried out over a range of temperatures for linear and branched polyethylenes in α‐chloronaphthalene solutions. In a number of cases the molecular size parameters have been found to depend on the solution temperature. When observed, the temperature dependence can change molecular weight values by as much as 50%. The temperature dependence tends to be more pronounced at higher molecular weights, in linear than in branched polyethylenes, and is particularly noticeable at solution temperatures below that of the normal crystalline melting temperature of the polymer. It is suggested that the temperature dependence of molecular weight parameters may be due to a gradual dissociation in solution of polymer aggregates arising from persisting interchain entanglements. A relationship was established between intrinsic viscosity and molecular weight for selected fractionated polyethylenes by using molecular weight data obtained under conditions unfavorable to the persistence of polymer aggregates. A number of published viscosity–molecular weight functions for polyethylenes was compared with the calibrated relationship. Some of the published equations gave results in good agreement with the present function, but a number of others resulted in gross overestimates of molecular weight. Polymer aggregation problems may have been encountered in the derivation of some of these viscosity–molecular weight functions. The comparison indicates the danger of indiscriminate choice of viscosity–molecular weight functions for use in rapid estimates of polymer molecular weight.
Radiolysis of polyisobutene. Part III. Effect of additives
Authors: Turner D. T. 
Published: April 2003

AbstractThe effect of various liquid additives on the degradation of polyisobutene exposed to 4 M.e.v. electrons has been studied by solution viscometry and by measurement of gas volatile at −196°C. At a concentration of about 10−4 mole/g. some additives result in an increased yield of fractures, the maximum observed being about 20% with nitrobenzene, presumably due to the scavenging of polymer radicals which otherwise would combine. At higher concentrations most additives result in a decrease in the yield of fractures. Thus, 2 × 10−3 mole/g. thiophenol decreases the yield by about two‐thirds and itself suffers sensitized decomposition as evidenced by an increase in the yield of gas from the irradiated mixture. In the simplest case, di‐n‐butyl disulfide has a symmetrical effect in suppressing part of the yield of fractures and gas. This is consistent with the view that a proportion of the fractures is associated with gas formation.