bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of temperature and strain rate on the stress‐strain curve of oriented isotactic polypropylene
Authors: Hall I. H. 
Published: April 2003

AbstractThe effect on the stress‐strain curve of oriented isotactic polypropylene of passing through the “glass transition” region, either by increasing the strain rate or decreasing the temperature, is to increase sharply the modulus at strains up to about 5% and the stress at break. The modulus at higher strains and the elongation at break are little affected, and even at a temperature of 90°K., well below the transition region, the extension at break is as large as 13%. Another effect of decreasing temperature or increasing strain rate is to remove the nonrecoverable components of the extension of the material. This is a different effect from the transition phenomenon since it occurs at a different combination of strain rate and temperature. The results at different rates of strain are described from the point of view of viscoelastic theory, and a treatment is described which gives a better description of the behavior than the more conventional spring‐dashpot models.
A theory of the thermodynamic behavior of nonelectrolyte solutions. VII. Partial miscibility in the system polystyrene–cyclohexane
Authors: Maron Samuel H. , Nakajima Nobuyuki 
Published: April 2003

AbstractMaron's theory of the thermodynamics of nonelectrolyte solutions has been used to obtain from published osmotic pressure, light‐scattering, and partial miscibility data for the system polystyrene‐cyclohexane (μ° – σ°) and σ° values as functions of molecular weight and temperature. These functions were combined then with intrinsic viscosities to calculate the partial miscibility curves for five samples of polystyrene of varying molecular weight. Except for minor discrepancies, which are shown to be due to molecular weight heterogeneity, the calculated plots are in good agreement with the experimental results. The data have also been used to evaluate the interaction parameters at the points of critical miscibility. These calculations confirm the predictions of Maron and Nakajima that for infinite molecular weight these parameters go to the limits μc° = 2/3, σc° = 1/6, (μc° – σc°) = 1/2, and μc = 2/3.
The influence of the structure of ion‐exchange polymers on ion‐exchange between polymers and electrolytes in solutions
Authors: Saldadze K. M. 
Published: April 2003

AbstractThe effect of the number of crosslinks in polymers on the ion exchange process has been investigated, assuming the exchanger to be a polyelectrolyte. An increase in the number of crosslinks (divinylbenzene content from 2 to 16%) has been found to cause no change in the character of the adsorption both in homovalent as well as heterovalent exchange. The processes obey the law of mass action regardless of whether contact is made between a polymer with varying divinylbenzene (DVB) content and solution of constant concentration or between one with constant DVB content and variously diluted solutions. With change in the crosslinking agent content of the polymer, the selectivity of ionic adsorption, which is determined by the property and size of the exchanging ions, varies. Changes in the number and arrangement of active groups in the polymer network have different effects on the ion exchange processes. An increase in the amount of active groups without marked changes in the swelling properties of the resin has no noticeable effect on the ion exchange processes, but as the concentration of active groups is increased with simultaneous increase in the specific volume of the resin considerable change in the selectivity of the ions being adsorbed takes place during the ion exchange process. With varying arrangement of the same active groups in the network of the ion exchanger, if different crosslinking agents are used in its synthesis its properties change, depending upon the medium in which the exchange is taking place. For example, the exchanger EDE‐10P synthesized on the basis of polyethylenepolyamine and epichlorohydrin may be considered to have practically only secondary and tertiary amine groups if one neglects a small amount of active groups of the quaternary ammonium bases. This exchanger adsorbs the anions of acids (H2SO4 and HCl) in acid medium and possesses a total exchange capacity of 10.5 meq./g. From a neutral medium (0.1N solution NaCl) it adsorbs about 0.95 meq./g. Cl−. On contact of the OH form of the resin with 0.1N CuSO4 and 0.02N H2SO4 it adsorbs 6.08 meq./g. SO42− and 5.75 meq./g. Cu2+ and on contact with 0.1N ZnCl2, 6.2 meq./g. Cl− and 5.92 meq./g. Zn2+. Under the same conditions the exchanger AN‐2F synthesized from phenol, polyethylenepolyamines, and formaldehyde and containing active N and NH groups practically adsorbs no copper. The capacity for CuSO4 adsorption by the anion exchanger EDE‐10P is not simple molecular sorption taking place with various exchangers on contact with acid and salt solutions. In this case, as has been demonstrated, complex compounds such as [(R2NH)2Me(H2O)2]X2 and [(R3N)2Me(H2O)2]X2 are formed. Such complexes are not formed by other anion exchangers containing secondary and tertiary amino groups.
Copolymerizations with triallyl cyanurate, triallyl isocyanurate, and diallylmelamine
Authors: Roth R. W. , Church R. F. 
Published: April 2003

AbstractReactivity ratios for the copolymerization of triallyl eyanurate, triallyl isocyanurate, and diallylmelamine with methyl methacrylate, styrene, and vinyl acetate have been determined. Integral composition distribution curves have been determined for the triallyl cyanurate‐methyl‐methacrylate system.
Cumene hydroperoxide‐initiated radical polymerization
Authors: Tobolsky A. V. , Matlack L. R. 
Published: April 2003

AbstractThe initial rates of solution polymerization of styrene and methyl methacrylate initiated by cumene hydroperoxide were determined at several temperatures. A new method of analysis of the kinetic data is presented. The results led us to conclude that the radicals which initiate polymerization are produced exclusively by bimolecular reactions, namely, a bimolecular reaction between hydroperoxide and solvent. For the latter reaction, benzene can be classified as very inert, but dimethylaniline, pyridine, and benzyl alcohol are quite active. Rate constants for the various initiating reactions are tabulated.
Rearrangement of a polymethylsiloxane by hydrogen chloride
Authors: Mayo Frank R. 
Published: April 2003

AbstractLinear decamethyltetrasiloxane (MD2M) was treated with hydrogen chloride in the presence of various amount of water or methanol at room temperature. In the presence of water, the rate and extent of cleavage and rearrangement increased with the concentration of hydrogen chloride and the volume of the aqueous phase. In a slow stream of hydrogen chloride gas, significant proportions of the MD2M were lost as chlorosilane vapors. Until an aqueous phase appears, M2D2 is fairly stable to dry hydrogen chloride. It is also stable to dilute aqueous hydrogen chloride, but, with an equal volume of saturated aqueous hydrogen chloride, 10–20% of the MD2M may react in an hour. Rearrangement and cleavage are accelerated by methanol and by tetrahydrofuran. The significance of these results is discussed.
The nature of the end products from the enzymic treatment of tropocollagen and collagen fibrils
Authors: Barkin Stanley M. , Oneson Irving 
Published: April 2003

AbstractTreatment of a solution of rat tail tendon collagen in acetate buffer with a proteolytic enzyme (ficin) led to a monodispersed solution of rodlike particles whose dimensions were 12.6 A. in diameter and 2400 A. in length. Similar enzymic treatment of dispersions of steer tendon collagen fibrils resulted in a disaggregation of the fibrils to a solution of particles of essentially similar dimensions. The nature of the enzymic attack in relation to the structure of the substrate is discussed.
Polymerization of vinyl monomers containing boron II. p‐vinylphenylboronic acid
Authors: Pellon Joseph , Schwind L. H. , Guinard M. J. , Thomas W. M. 
Published: April 2003

Abstractp‐Vinylphenylboronic acid was prepared by the reaction of p‐vinylphenyl magnesium chloride with tributyl borate. It is similar to styrene in respect to rate of free radical polymerization. Loss of boron is not significant during polymerization or handling. The polymer is a polyelectrolyte, soluble only in liquids containing some water. Films are clear, colorless, and brittle. On heating the polymer first becomes crosslinked by dehydration, then undergoes severe weight loss at 380 to 400°. Copolymerization behavior is that of an active monomer with an electron‐deficient vinyl group.
Copolymerization of methacrylic anhydride with vinyl monomers
Authors: Hwa Jesse C. H. , Miller Leon 
Published: April 2003

AbstractCopolymerizations of methacrylic anhydride and a variety of common types of vinyl monomers were conducted in bulk and in solution at 60–80° with benzoyl peroxide catalyst. The copolymers were characterized by conversion, solubility in hot dimethyl sulfoxide, elementary analysis, and infrared spectroscopy. A copolymer composition equation was derived for a special divinyl–vinyl system in which the divinyl monomer would cyclize extensively during polymerization and give rise to soluble, although perhaps branched, copolymers. The results showed that both soluble and insoluble copolymers were obtained, depending on the comonomer used and experimental conditions under which the copolymerization was carried out. In general, soluble copolymers were formed under the following conditions: (a) the less reactive the comonomer in free radical copolymerizations; (b) the greater the dilution; (c) the greater the difference in the moles of the two components in charge; and (d) the lower the conversion. According to reactivity ratio determinations and a comparison with published data, the anhydride ring radical behaved like a methyl methacrylate radical. The key step which led to gelation was believed to be “ring interruption” by the comonomer (CH2 = CHR):

The question why methacrylic anhydride does not gel in homopolymerization, however, still remains unresolved.
Investigations of the chemical conversions of polycarbonates
Authors: Ya. Yakubovich A. , Ya. Gordon G. , Maslennikova L. I. , Grobman E. M. , Tret'Yakova K. I. , Kokoreva N. I. 
Published: April 2003

AbstractPolycarbonates, in particular poly‐4,4′‐bis(hydroxyphenyl)‐2,2‐propane carbonate, are distinguished by their thermal stability and may be processed at temperatures about 300°. The present report deals with some chemical conversions of this polymer, taking place in solution and in the molten state. In the fractional precipitation of the polymer from chloroform solutions by methyl alcohol an enhanced yield in the low molecular fraction is observed, the latter continually forming even on repeated precipitation. If a small amount of methanol, insufficient to precipitate the polymer, is added to the chloroform solution, a gradual fall in viscosity (which does not occur in absence of the alcohol) is observed. The reaction is accelerated in the presence of hydrogen chloride. Such precipitants as acetone and petroleum ether do not cause this effect. Alcoholysis is a characteristic reaction of the polycarbonates, taking place at a relatively high rate. An alcoholic solution of alkali will decompose the polycarbonate at room temperature and especially rapidly (within a few minutes) on boiling. In this way one may obtain with high yield bisphenol used for the synthesis of the polymer. The melting of polydisperse polycarbonates (ca. 300°) in the absence of atmospheric oxygen leads to a very rapid (10–60 min.) levelling of the molecular chain lengths and hence to decrease in polydispersity (according to fractional precipitation data), causing a corresponding fall in the viscometrically determined molecular weights. Such levelling annuls the harmful effect of the low molecular fractions on the properties of the material. At higher temperatures (350°) decarboxylation (evolution of CO2) is quite marked, and the formation of a certain amount of three‐dimensional polymer may be observed. Polycarbonates prepared by the heterophase polycondensation of phosgene with phenolates, for instance, 4,4′‐bis(hydroxyphenyl)‐2,3‐propane and containing hydroxyl and acyl chloride endgroups are capable of undergoing further polycondensation on heating to 270–300°C. for 30–60 min. or more. Hydrogen chloride is evolved. As a result the mean viscometric molecular weight may increase three‐ to fourfold in comparison with the initial compound. Additional polycondensation in the melt may also proceed by another pathway, without hydrogen chloride evolution but as the result of the elimination of a certain amount of 4,4′‐bis(oxyphenyl)‐2,2‐propane on endgroup interaction. This reaction is catalyzed by small quantities of titanium alcoholates. The high lability of the ester links in polycarbonates may also be illustrated on the example of the interaction between these polymers and other esters, in particular with polybis(phenyl)‐2,2‐propane terephthalate [OC6H4C(CH3)2C6H4OCOC6H4COO]. The reaction taking place without catalyst at temperatures above 300° results in a mixed polyster carbonate with composite properties.
Proton magnetic resonance relaxation in a series of dimethylsiloxane polymers
Authors: Powles J. G. , Hartland A. , Kail J. A. E. 
Published: April 2003

AbstractMeasurements of the longitudinal and transverse proton magnetic resonance (p.m.r.) relaxation times are reported for a series of unadulterated dimethylsiloxanc polymers over the temperature range ‐180 to +250°C. At lower temperatures the measurements were made with steady‐state broad‐line apparatus, and at higher temperatures, with spin echo equipment. The polymers ranged in molecular weight from a fluid of 3 cs. (centistoke) viscosity at 25°C. to a gum of 107 cs. The changeover from liquidlike to polymerlike properties with increasing chain length is discussed. All the samples showed high apparent crystallinity a t low temperatures as determined by p.m.r., annealed samples appearing in some cases to be over 90% crystalline. The crystal melting transition occurs within two or three degrees but is subject to supercooling. Signals from the crystalline and amcrphous regions differ considerably. In the liquids the transverse decay is complex and is thought to be owing to a slowly modulated nuclear magnetic interaction between the methyl groups and may be described as a narrowbroad line. The estimated correlation frequencies for proton motion correlate quite well at both high and low temperatures with the few dielectric measurements available showing how the methyl protons move with the SiO bond. Some evidence is found for a slower motion which is associated with chain drifting and for which the magnetic interaction may be within or between chains. A study of the same materials when crosslinked shows, among other things, the importance in p.m.r. of residual unlinked material. Removal of unlinked material leaves samples which show that crosslinking changes the p.m.r. behavior in important respects and aids in distinguishing the effects of local and large‐scale molecular motions. A study of the effects of extent of crosslinking and the various methods of crosslinking by p.m.r. will be valuable. Interpretation of the results is greatly handicapped by a serious lack of scientific data about the polydimethylsiloxanes, especially those at low temperatures.
Viscosity measurements on oligoesters from terephthalic acid and glycol
Authors: Seidel B. 
Published: April 2003

AbstractViscosity measurements on a series of linear oligoesters of terephthalic acid and ethylene glycol BzO‐T‐(G‐T‐)nOBz, n = 0–5 with molecular weights from 350 to 1300 at 50.0°C. in tetrachloroethane give a relationship [η] = 1.38 × 10−2 × M0.87 for the higher members of the series. The Kuhn equation [η]v = 2.5 + p2/8, connecting viscosity with the axial ratio of the solute molecules, is found to hold reasonably well at its lower limit, also, for the determination of the axial ratio of small molecules. An attempt is made to calculate the overall dimensions of the solute molecules.
Thermodynamic properties of polystyrene and styrene
Authors: Warfield R. W. , Petree M. C. 
Published: April 2003

AbstractA Tarassov function has been used to estimate the specific heat of polystyrene between 0° and 60°K. These data, together with published Cp data, have been used to calculate the entropy, enthalpy, and free energy of styrene and polystyrene from 0° to 298.16°K. The entropy of polymerization of styrene at 298.16°K. was found to be 26.69 cal./mole°.The thermodynamic function Cp/T versus T as calculated for polystyrene, increases to a maximum at 65°K. and then increases again at the glass transition temperature. The Tarassov function, which is shown to be useful in estimating the specific heat of amorphous polymers, should be combined with a T3 Debye function to yield more accurate cv data at low temperatures. The number of classically vibrating units per repeating unit of polystyrene was found to be 6.57. The difference Cp – Cv was calculated at 273°K. and found to be 2.0 cal./mole°.
Synthesis and polymerization of an alkene‐substituted norbornylene
Authors: Dekking Henri G. G. 
Published: April 2003

AbstractBicyclo[2.2.1]‐hept‐2‐ene‐5‐butylene was synthesized in 20% yield by reacting equimolar amounts of cyclopentadiene and 1,5‐hexadiene at 190°C. for 16 hr. The same product was obtained by forming the Diels‐Alder adduct of cyclopentadiene and allylchloride (60% yield), making this adduct react with magnesium to form the Grignard reagent (99% yield), and then coupling the Grignard reagent with allylbromide (46% yield). The monomer was polymerized at 25°C. by means of a LiAl(decyl)4‐TiCl catalyst. Infrared analysis of the polymer indicates that the monomer polymerizes as a substituted norbornylene and as a cycloalkane‐substituted alpha‐olefin. The polymer is soluble in benzene and softens at 150°C.
Collective interactions in polymerization processes at low temperatures and in polymers with conjugated bonds
Authors: Semenov N. N. 
Published: April 2003

AbstractThe first part of the paper is concerned with low‐temperature polymerization, and a hypothesis explaining its mechanism is proposed. Physical properties of new classes of polymers are discussed in the second part. The importance of electron collectivization and energy levels both in polymerization processes and in physical properties is emphasized.
Trifluoronitrosomethane/tetrafluoroethlylene elastomers dilute solution properties and molecular weight
Authors: Morneau G. A. , Roth P. I. , Shultz A. R. 
Published: April 2003

AbstractThe copolymer prepared from tetrafluoroethylene and trifluoronitrosomethane was studied by light scattering in 1,1,2‐trichloro‐2,2,1‐trifluoroethane (Freon 113) and by solution viscosity in Freon 113 and perfluorotributylamine (FTBA). Molecular weights ranging from 2 × 105 to 2.4 × 106 were measured. Viscosity–molecular weight relationships were obtained for both solvents. They are:
The extreme resistance of the polymer to nonfluorinated solvents is explained on the basis of its low solubility parameter, δ, which was established to be 5.2. From a consideration of the root‐mean‐square end‐to‐end chain length, the freely jointed segment is 24 chain atoms. Fractionation of the polymers shows a wide range of molecular weights with an abnormally large, low molecular weight portion.
Synthesis and properties of some aromatic polymers
Authors: Berlin A. A. , Liogon'Kiǐ V. I. , Parini V. P. 
Published: April 2003

AbstractMultinuclear aromatic compounds are distinguished by considerable thermostability. In a number of cases they have been shown to be endowed with semiconductor properties. In view of this the development of a method of synthesis and investigation of aromatic polymers with a common system of conjugated bonds has both theoretical and practical interest. Such substances have been synthesized by the authors on decomposing bisdiazo compounds by an ammoniacal solution of univalent copper, and also on decomposition of bisnitroso acetates. In particular, 4,4′‐bisdiazobiphenyl, 4,4′‐bisdiazobitoyl, 4,4′‐bisdiazobiphenyl‐3,3‐dicarboxylic acid, and benzidine N,N′‐bis‐nitroso acetate were employed. On decomposition of the bisdiazo compounds a powder of orange to brown color was formed, soluble in concentrated sulfuric acid and isoluble in most organic solvents. Analysis showed it probably to possess the composition:
where R may be H, COOH, or CH3. On the average one azo group is present for each 4–10 benzene rings and two chlorine atoms for each 10–20 rings. The mean molecular weight determined for one of the carboxylated polymer specimens was found to be 3000. On heating to 400° the polymer decarboxylates. At 450° decomposition sets in. Viscosity curves of the solutions (plots of ηsp/C vs. C) exhibit an anomalous rise within the limits C = 0.1–1%. The concentration of unpaired electrons in the polymers was shown by the electron resonance method to be ∼1019/g. Heating the substances leads to an increase in concentration of unpaired electrons by 1–2 magnitudes. The spectra and x‐ray diagrams of the substance were obtained. Evidently the formation of polymers from bisdiazo compounds is of a radical nature, leading to the formation of stable radicals of low activity. Low molecular fractions isolated from the polymers are fusible and soluble in benzene. They are capable of reacting with diethynylbenzene with the formation of nonmelting and insoluble thermostable products. Carboxylated polymers form salts with transition elements that evidently are of the nature of intracomplex compounds with intermolecular crosslinkage. Products of the decomposition of benzidine bisnitroso acetate are in general similar to those resulting from bisdiazodiphenyl, but contain less unpaired electrons.
The radiation‐induced graft copolymerization of 4‐vinyl pyridine and acrylamide to nylon 6.6
Authors: Sykes J. A. W. , Thomas J. K. 
Published: April 2003

AbstractAppreciable quantities of 4‐vinyl pyridine and acrylamide have been grafted to nylon 6.6 by decomposing in their presence the peroxides and hydroperoxides formed on irradiating the polymer in air with γ‐rays. The kinetics of the grafting process is interpreted in terms of a diffusion of the monomer into the nylon. The enhanced dyeing of the amine grafts and the lowering of the surface resistance of the graft by quaternization with dimethylsulfate are also reported.
The reaction of ozone with surfaces of natural rubber, and its dependence upon strain
Authors: Andrews E. H. , Braden M. 
Published: April 2003

AbstractThe progressive reaction of ozone with surfaces of natural rubber (cis‐polyisoprene) has been studied by means of replica electron microscopy. Unstrained rubber suffered surface degradation at a rate consistent with the predictions of a theory of diffusion with simultaneous chemical reaction. In strained surfaces the rate of ozone penetration was appreciably greater, but this is attributed to physical rather than chemical causes. Sites of preferred reaction (etch pits) were observed in both strained and unstrained specimens, the former also displaying oriented fissure systems. The origin of these features is explained in terms of Griffith's criterion and it is necessary to postulate, in the unstrained specimens, pre‐existing surface strains. The relation of the microscopic etch and fissure patterns to macroscopic ozone cracks is briefly discussed.