bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer association. II. Osmotic pressure of an associating polymer in mixed solvents
Authors: Morawetz H. , Gobran R. H. 
Published: April 2003

AbstractThe osmotic molecular weight of a copolymer of 5 mole per cent methacrylic acid and 95 mole per cent methyl methacrylate in benzene at 29.8°C. indicates considerable molecular association, with the size of the molecular aggregate constant over a wide range of solution concentration. This behavior is consistent with a model in which the copolymer contains on the average less than two carboxyls free to participate in intermolecular association, which proceeds virtually to completion. It is shown that equilibrium constants for the association of the carboxyl groups of the polymer with cosolvents can be estimated from the dependence of the apparent molecular weight on cosolvent concentration.
A viscosity study of polyelectrolytes in the presence of added salts
Authors: Contois L. L. , Trementozzi Q. A. 
Published: April 2003

AbstractThe effect of various added simple electrolytes upon the solution viscosity of polymethacrylic acid and hydrolyzed polyacrylonitrile was studied. The viscosity behavior of these polymers in water and in the presence of added NaCl was typical of that of polyelectrolytes. The addition of multivalent anions (sulfate, diacid phosphate, oxalate, and succinate) to solutions of polymethacrylic acid decreasesd the viscosity at low added salt concentrations, but a reversal in the reduced viscosity–concentration curve was obtained as the ionic strength was increased. This increase in viscosity can be partly explained on the basis of increased ionization originating from the behavior of the added multivalent anions. However, this is not the complete explanation since the relative efficiency of these anions in increasing the viscosity is not consistent with the values of the dissociation constants. A possible alternative explanation involves the formation of associated complexes of the polyions. It is further demonstrated that the limiting intrinsic viscosities at infinite ionic strength is dependent upon the initial polymer charge.
Dynamic mechanical properties of polystyrene, polyethylene, and polytetrafluoroethylene at low temperatures
Authors: Sauer J. A. , Kline D. E. 
Published: April 2003

AbstractA study of the dynamic mechanical properties of several high polymers has been made over a temperature range from 80°K. to above room temperatures and at frequencies in the range from 200 to 4000 cps. For amorphous polymers such as polystyrene the mechanicalloss rises sharply in the neighborhood of 80°C. but over the rest of the temperature range studied exhibits no relaxation peaks. For partly crystalline polymers such as polymethylene, polytetrafluoroethylene, and nylon the loss curve exhibits one or more definite internal friction peaks in the temperature range studied. The observed relaxation behavior is discussed in terms of possible molecular mechanisms and the results correlated with specific heat measurements and other mechanical loss measurements where such data are available.
Viscometric behavior of polyacrylate ion in concentrated salt solutions
Authors: Kagawa Ikumi , Fuoss Raymond M. 
Published: April 2003

AbstractViscosities of polyacrylate ion in the presence of potassium bromide, sodium bromide, lithium bromide, sodium iodide, sodium hydroxide, and hydrochloride acid in aqueous solution were measured over the approximate ranges 0.0–0.6% polymer and salt up to saturation with respect to polyacrylate or to salt. The general initial effect of added electrolyte is to reduce the ratio ηsp/c and to convert the curve characteristic of polyelectrolytes into a straight line, which can be extrapolated to zero polymer concentration to given [η], the intrinsic viscosity of the polymer in the presence of excess salt. Sodium hydroxide and sodium bromide produce minima in plots of [η] against salt concentration. Sodium iodide precipitates polyacrylate at 1.5 N iodide as a translucent gel, which redissolves at 3.0 N and finally reprecipitates at 6 N. In the latter range of concentration, [η] exhibits a maximum. Both by‐ions and counter‐ions have specific effects on the viscosity of the polyion.
Alkyl thiolacrylates: Their preparation and polymerization
Authors: Marvel C. S. , Jacobs S. L. , Taft W. K. , Labbe B. G. 
Published: April 2003

AbstractA convenient synthesis of alkyl thiolacrylates has been described and a number of the intermediates, as well as the esters, have been characterized. These esters have been found to homopolymerize readily under free radical conditions to give clear plastics which have higher softening points than the corresponding acrylate ester polymers. In general the thiolacrylates copolymerize readily with common vinyl monomers. The reactivity ratios for copolymerization with butadiene have been found to be r1 (butadiene) = 0.35 ± 0.01 and r2 (methyl thiolacrylate) = 0.20 ± 0.05. The butadienemethyl thiolacrylate copolymer prepared from a 90/10 charge ratio to a 45% conversion contained 18.1% of combined methyl thiolacrylate. Tests on the compounded and cured polymer indicate that it has properties very close to those of standard GR‐S, except for its higher temperature rise.
The melting behavior of polybutadienes
Authors: Mandelkern L. , Tryon M. , Quinn F. A. 
Published: April 2003

AbstractThe melting temperatures of five emulsion polymerized polybutadienes containing varying amounts of trans‐1,4 units were determined. Since slow heating rates were used subsequent to the initial crystallization, melting temperatures were observed that were appreciably higher than previously indicated. The data were analyzed according to the theory of the melting point depression of copolymers, and a lower limit for the heat of fusion per 1,4‐trans unit of 18.5 cal./g. was obtained. This value is larger than that for natural rubber and explains why calorimetric measurements of the heat of fusion apparently give abnormally high values. The index of refraction and densities of the amorphous polymers were determined at 25°C. and the specific refractivities found to be constant and independent of polymer constitution in the composition range studied.
The ultimate properties of simple elastomers
Authors: Bueche A. M. 
Published: April 2003

AbstractA criterion for the rupture of simple elastomers is postulated and its consequences examined. The criterion assumes that the sample will break when the rate of increase of tension due to further elongation is equal to the decrease due to bond rupture. The former is computed from the rate of strain and the form of the stress‐strain curve. An expression for the latter is found using reaction rate considerations. The resulting expression represent the experimental data on the rupture of polydimethylsiloxanes within the limits of experimental error. The free energy of activation for bond rupture obtained from the tensile data, by use of the theory, at one temperature is in approximate agreement with the activation energy obtained from stress relaxation measurements at several temperatures.
Electron exchange‐polymers. V. Hydroquinone‐formaldehyde polymers
Authors: Verplanck Vincent , Cassidy Harold G. 
Published: April 2003

AbstractHydroquinone‐formaldehyde and related polymers were prepared and examined for oxidation‐reduction properties in a preliminary way. Instability toward oxidizing agents and alkali was shown by the polymers, and further study of them was suspended. Where this work is related to that of G. Manecke, the two are in general agreement. Instability toward an oxidizing agent (iodine in KI at pH 8) was shown also by the products resulting from the treatment of several commercial sulfonated phenol‐formaldehyde ion exchange resins, and a 7:6 phenol‐formaldehyde novilac with Fremy's salt, or with diazotized sulfanilic acid, followed by reduction with sodium hydrosulfite, to produce catechol‐ or hydroquinone‐type residues.
Sulfinic acid derivatives as accelerators in the polymerization of methyl methacrylate
Authors: Brauer G. M. , Burns F. R. 
Published: April 2003

AbstractA study was made of the efficiency of amine salts of p‐toluenesulfinic acid as accelerators in the polymerization of methyl methacrylate. These compounds are readily synthesized by addition of amine to the ether solution of the sulfinic acid. Most of the salts are stable in air. Salts of secondary and tertiary aromatic amines, such as the methylaniline or dimethyl‐p‐ toluidine salts, are very efficient accelerators in the benzoyl peroxide‐initiated polymerization. However, colored products are formed. Aliphatic amine salts as well as the free acid give colorless polymers, but the setting time is increased considerably. Heterocyclic amines show reduced activity as polymerization accelerators. The setting times of monomer–polymer mixtures containing some of these accelerators have been determined. Physical properties of the polymers have been evaluated by measuring their resistance to indentation and recovery.
Infrared studies on chlorinated rubbers
Authors: Ramakrishnan C. S. , Dasgupta Sharda , Pande J. B. 
Published: April 2003

AbstractThe changes in the infrared absorption spectra accompanying the chlorination of unmasticated deproteinized natural rubber dissolved in carbon tetrachloride, with phenyl iododichloride, are reported. The 6% chlorine content product shows, in general, decreased absorption in the 8–11 μ region. The spectrum of 6% chlorine content product is markedly different from that of fully chlorinated rubber. The 19% chlorine content product is intermediate to that of 6–51% and shows some of the characteristics of fully chlorinated rubber, while retaining part of the characteristic absorption of natural rubber. The spectrum of the fully chlorinated product is similar to that of hydrochlorinated rubber and chlorinated rubber obtained by the gaseous chlorine reaction.
Chain scissions in a polymer network
Authors: Horikx M. M. 
Published: April 2003

AbstractRelations between the soluble fraction and the number of effective chains between crosslinks in a three‐dimensional network undergoing a scission reaction have been derived. Three limiting cases have been considered: (a) random scission in the chains, (b) scission in the chains directed by the crosslinks, and (c) scission of the crosslinks. The number of scissions can be computed from the fraction of soluble material in a degraded network, as determined experimentally. This procedure has been applied to the oxidation of a natural rubber vulcanizate. In a natural rubber sulfur‐Santocure vulcanizate, the scission reaction accompanying the oxygen absorption at 100°C. does not involve opening of the crosslinks, but it remains undecided whether the scission in the chains is directed or at random. At each chain scission about 5–10 molecules of oxygen are taken up by the rubber at 100°C. under various conditions, this number being apparently independent of the rate of oxidation, the absence or presence of antioxidants and metal stearates as catalysts, and the oxygen pressure.
Determination of the second virial coefficient in dilute polymer solutions from light scattering data
Authors: Fleming P. , Peacocke A. R. , Wallis R. G. 
Published: April 2003

AbstractVarious methods are discussed of utilizing light scattering data obtained at only one angle (other than measurements to determine the intrinsic dissymmetry), in order to obtain values for the second virial coefficient. Illustrative data from light scattering measurements at two wave lengths using a sample of sodium polyglutamate from Bacillus anthracis are presented.
Reaction of ozone with natural hevea and acrylonitrile‐butadiene rubbers
Authors: Kendall F. H. , Mann J. 
Published: April 2003

AbstractThe physical changes that occur when ozone reacts with unvulcanized rubber or unstretched vulcanizates have been studied. The speed of reaction is controlled by diffusion of gas into the rubber; as a consequence, initial products formed near the surface are subjected to further action by ozone. To minimize this possibility experiments have been carried out with thin films of Hevea rubber and monolayers of Hycar OR‐15, and the products have been characterized by infrared spectroscopy. The results are considered in relation to observations on the ozonization of simpler compounds recorded in the literature. It is concluded that, during ozonization there is a spontaneous scission at the carbon‐carbon double band with the production of aldehyde and/or ketone and a peroxy biradical. The measurements show the presence of a reaction which is inhibited by 1% phenyl‐β‐naphthalamine and which is presumably a chain reaction. The nature of this chain reaction is discussed and it is shown that suppression of this reaction does not prevent the cracking of stretched vulcanizates. The suggestion is made that the characteristic feature of cracking is a reaction which takes place in a thin layer at the surface of the rubber.
Methanolysis and hydrolysis of cotton cellulose III
Authors: Nelson Mary L. , Segal Leon , Mares Trinidad , Creely Joseph J. 
Published: April 2003

AbstractWell‐decrystallized cotton yarn, the remaining organized regions of which consisted predominantly of crystalline cellulose III, was subjected to partial solvolysis in aqueous and methanolic hydrochloric acid. From x‐ray examination of the residues a hypothesis is advanced regarding the reversion of cellulose III to cellulose I. The viscometric data indicated identical values of leveling‐off degree of polymerization by hydrolysis and by methanolysis, which is at variance with certain published data showing lower values for methanolysis. The data therefore neither support nor disprove the idea of recrystallization during hydrolysis, but indicate the need for further work along these lines.
Crosslinking of polyethylene‐type polymers by high‐energy irradiation
Authors: Okamoto H. , Isihara A. 
Published: April 2003

AbstractEffects of high‐energy radiation on polyethylene‐type polymers were considered. At the initial stage of irradiation, crosslinking, double bond formation, and hydrogen evolution are proportional to the radiation dose. The efficiency of irradiation in forming an infinite network was estimated. It depends on the mobility of decomposed atoms or radicals in the solid polymers.
Decomposition of benzoyl peroxide in dilute solutions
Authors: Barson C. A. , Bevington J. C. 
Published: April 2003

AbstractA study of the decomposition of benzoyl peroxide in very dilute solutions is reported. This work is preliminary to a detailed investigation of the mechanism by which the peroxide initiates radical polymerizations; 14C‐benzoyl peroxide has been used. In dilute solutions in benzene, almost all the benzoate radicals generated from benzoyl peroxide lose carbon dioxide before they can enter into other reactions; various substance e.g., diphenylpicrylhydrazyl, styrene, and cumene, which can react with free radicals, decrease the yield of carbon dioxide.
Preparation and properties of fibers containing mixed polymers. I. Polyacrylonitrile‐cellulose acetate fibers
Authors: Cates David M. , White Howard J. 
Published: April 2003

AbstractFibers containing both polyacrylonitrile and cellulose acetate were spun using dimethyl formamide as a solvent. The relative polymer proportions ranged from 100% polyacrylonitrile to 20% polyacrylonitrile. The x‐ray diffraction patterns, optical appearance, solubility, density, absorptive capacity for water and dyes, electrical resistivity and mechanical properties of the fibers were studied, and experimental results are given. In addition several experiments bearing on the structure of the fibers and the compatibility of the spinning solutions are reported. The results indicate that the fibers contain discrete regions of each polymer. It is probable that, for most of the relative concentration range, continuous networks of each polymer extend throughout the fiber. In addition void spaces, probably resulting from the drawing of the fibers, appear to be present.
Tensile stress in jets of viscoelastic fluids. I
Authors: Gill Stanley Jensen , Gavis Jerome 
Published: April 2003

AbstractExperimental observations have been made on jets of a viscoelastic fluid (carboxy‐methylcellulose–water solutions). The jet was subjected to transverse vibrations by the nozzle. The resulting wave pattern of the jet was compared to the theoretical results of three mechanisms of wave propagation: tension, rigidity, and elastic stretching. The results conform to the case of tension, and thus demonstrate the existence of a tensile stress in jets of viscoelastic fluids.
Characterization of graft polymers
Authors: Blanchette Joseph A. , Nielsen Lawrence E. 
Published: April 2003

AbstractTwo styrene‐rubber polymers were prepared by mass polymerization and fractionated to isolate the insoluble graft portions of each. These graft fractions were analyzed by two methods (titration and infrared) for unsaturation. Cleavage at the hydroxylated double bonds was carried out and the polystyrene chains were isolated. A diagrammatic structure for the insoluble graft material has been calculated from the length and number of the polystyrene chains isolated by the cleavage technique. The physical and mechanical properties of the gel fractions are reported.
Application of the theory of absolute reaction rates to the creep failure of polymeric filaments
Authors: Coleman Bernard D. 
Published: April 2003

AbstractA discussion is given of the creep failure of partially oriented polymeric filaments. The theory of absolute reaction rates is used to obtain differential equations which permit the calculation of the lifetime of a single filament when it is subjected to different uniaxial loading histories. Explicit expressions are obtained for the lifetime of a filament for three special cases: dead loads, increasing linearly with time, and sinusoidal loads. Results of lifetime under dead load measurements are presented for drawn 66 nylon yarns. The treatment of the data by the theory yields plausible values for the molecular parameters involved. It is shown that the parameters which are calculated from the dead loading experiments may be used to calculate the dependence of the tensile strength on the speed of measurement (when obtained using a constant rate of loading tester). Tensile strength values were measured at rates of loading in the range between 0.14 × 109 and 4.8 × 109 dynes cm.−2 sec.−1 and found to be in satisfactory, agreement with those predicated by the theory.
Poly‐α,β,β‐trifluorostyrene
Authors: Livingston Daniel I. , Kamath Pandurang M. , Corley Richard S. 
Published: April 2003

AbstractAn improved preparation and handling procedure for the monomer is described. The polymer was prepared best by emulsion polymerization, although anionic polymerization was also found to be operable. A number of properties of the polymer are described, including solubility, the infrared absorption spectrum, x‐ray diffusion (amorphous scattering), dielectric constant (2.56 ± 0.05), and dielectric loss tangent (0.0006 to 0.0035 over the range 102 to 1011 c.p.s.). Copolymerization with trifluorochloroethylene gave a copolymer containing 0.096 mole fraction of trifluorochloroethylene, and with styrene a copolymer containing 0.397 mole fraction. The copolymerization curve and constants for copolymerization with styrene are presented and discussed.
Fractionation of polyethylene
Authors: Tung L. H. 
Published: April 2003

AbstractCommercial polyethylenes were fractionated at 130°C., 15 degrees above the crystalline melting point of the polymer. Both extraction and precipation techniques were used. The solvent was xylene, and the nonsolvent was triethylene glycol. The inherent viscosities of the fractions were measured and the differential and integral distribution curves were presented. A method of constructing the differential and integral distribution curves was discussed. Using this method, fractionation data can be smoothed out from a linear plot, and the graphic differentiation step in constructing differential distribution curves can be eliminated.
The effects of crystallization and drawing on the viscoelastic properties of fibers
Authors: Tokita Noboru 
Published: April 2003

AbstractThe viscoelastic properties of four kinds of nylon‐6 and viscoses rayon having various degrees of crystallinity and of drawing are studied. The crystallinity is estimated from the density measurement for nylon‐6, while for viscose rayon it is determined by the acid hydrolysis method of Nickerson. The various kinds of measuring instruments are described by which the complex Young's modulus of fiber monofilament is measured over a wide range of frequency. The dynamical measurements for both materials are made over the frequency range from 0.047 c./sec. to 100 kc./sec. at 20°C. and 66% RH, and then the spectra of relaxation times and the distribution function of retardation times for each sample are obtained. From the experimental results, it is concluded that the mechanical dispersion found in the audio‐frequency range for partially crystallized nylon‐6 is due to the motion of segments in strained amorphous parts. The distribution function of retardation times for the heat conditioned nylon‐6 is well represented by a Cole‐Cole's distribution function with β = 0.29. On the other hand, the shock‐cooled nylon‐6 shows distinctively a non‐linear property at the strain of order of 10−3. Besides, it is found that the increase of the degree of crystallinity and drawing results in shifting the dispersion regions, as a whole, to longer time regions, and that the shapes of spectra of relaxation times are almost independent of the degree of crystallinity, while the shapes of spectra corresponding to wedge‐type spectra become less steep with increase of the degree of mechanical drawing. These facts are attributed to the sterile hindrance against the segmental motion. As regards viscose rayon, the mechanical dispersion represents itself at about 65°C. in 65% RH, and the activation energy for the segmental motion in amorphous parts is about 190 Kcal/mole. The water molecules adsorbed in fibrous structure are supposed to be playing the role of a plasticizer. The degree of crystallinity (70–75%) does not affect the mechanical behaviours of viscose rayon so much.
Molecular orbital theory of reactivity in radical polymerization. Part II
Authors: Hayashi K. , Yonezawa T. , Nagata C. , Okamura S. , Fukui K. 
Published: April 2003

AbstractSeveral problems in the process of radical polymerization, e.g., the relation between the chemical structure of vinyl monomer and its chemical reactivity, the prevalence of head‐to‐tail configuration, the reactivity of initiator radicals, the alternation tendency in heteropolymerization, and the relative ease of coupling in several cases of homopolymerization, are treated by the theory previously proposed by the present authors, in which reactivity is represented by the magnitude of stabilization energy due to π conjugation between a monomer and a radical in the transition state. In addition, a brief discussion on the existing theories of reactivity and some applications of Hush's method to the problem of termination are presented. The agreement between results of calculation and experiment is shown to be almost statisfactory.