bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation‐induced copolymerization of ethylene and sulfur dioxide in the liquid and gas phases
Authors: Colombo P. , Fontana J. , Steinberg M. 
Published: April 2003

AbstractThe radiation‐induced copolymerization of ethylene and sulfur dioxide has been studied in the liquid and gas phases. In the liquid phase, the copolymer composition remained equimolar over a temperature range of 20–160°C. and ethylene pressures of 50–680 atm. The rate of copolymerization in the liquid phase at 680 atm. increased with temperature to a maximum value at ∼80°C. Above this temperature the rate steadily decreased to zero at 157°C. because of temperature‐dependent depropagation reactions. In the gas phase, copolymers were formed that contained from 9 to 46 mole‐% sulfur dioxide. Under constant conditions of temperature, pressure, and radiation intensity, the copolymerization rate in the gas phase increased with increasing sulfur dioxide in the initial gas mixture. The propagating species for the liquid‐phase experiments is considered to consist of an equimolar complex molecule of ethylene and sulfur dioxide. For gas mixtures containing an excess molar concentration of ethylene, the propagating species are ethylene and the complex molecule. Infrared spectra show polysulfone structures. Calorimetric and x‐ray diffraction analyses indicate crystalline structures for copolymers in the range 9–50 mole‐% sulfur dioxide, although a melt transition temperature could not be observed for copolymer containing >31 mole‐% sulfur dioxide. Clear uniform film was obtained with copolymers containing up to 31 mole‐% SO2.
Isomerization of cis‐1,4‐polybutadiene by RhCl3·3H2O
Authors: Hrabak Frantisek 
Published: April 2003

AbstractThe isomerization of cis‐1,4‐polybutadiene by RhCl3 in aqueous emulsion was studied. The reaction was found to be slowed down by air and by base but not by quinone and was independent of the polymer solvents. Quinone did not suppress polymer gel formation. The results obtained suggest a nonradical mechanism of these reactions.
Kinetics of high‐intensity electron‐beam polymerization of a divinyl urethane
Authors: Labana S. S. 
Published: April 2003

AbstractThe kinetics of high‐intensity electron beam‐induced polymerization of di(2′‐methacryloxyethyl)‐4‐m‐phenylenediurethane during the network formation has been studied up to complete gelation and up to 56% conversion of unsaturation. From experimentally determined gel fractions, rate of disappearance of unsaturation, kinetic chain length, and intensity dependence, it is proposed that the polymerization takes place in a swollen network where the growing chains undergo unimolecular termination, and where gel‐gel reaction is prohibited. The rate expression derived is: In [α(1 − g)0.545] = In α0 − 2.51 kikpt/kt where α is the total unsaturation and g is the gel fraction. The value of kp/kt is found to be 2.1 and that of GR, the free radical yield per 100 eV absorbed, to be 16; these high values are ascribed to the high viscosity of the polymerizing system.
Extrathermodynamic approach to the study of the adsorption of organic compounds by macromolecules
Authors: Hansch Corwin , Helmer Friederike 
Published: April 2003

AbstractBy using substituent constants and regression analysis, an analysis has been made of the binding of derivatives of aniline and acetanilide to nylon and rayon, the experimental data of Ward and Upchurch being used. The amount of organic compounds bound from an aqueous solution by these two types of synthetic macromolecules is shown to be related to the octanol–water partition coefficients P. In the case of the aniline derivatives, where the basicity of the compounds varied considerably, a good model describing binding results from the linear combination of the two parameters related to free energy, i.e., log P and ΔpKa. The latter term is the difference between pKa for aniline and a particular derivative. For the neutral acetanilides a simple linear free‐energy relation between log P and log K is found. Of special note is the fact that the dependence of binding of these two classes of compounds to two classes of synthetic macromolecules as indicated by the coefficient with the log P term very closely parallels that found for a variety of biopolymers. The mechanism of hydrophobic binding seems to be the same in both the synthetic and natural polymers.
Thermal degradation of copolymers of methyl methacrylate and methyl acrylate. I. Products and general characteristics of the reaction
Authors: Grassie N. , Torrance B. J. D. 
Published: April 2003

AbstractThe technique of thermal volatilization analysis (TVA), applied to methyl methacrylate–methyl acrylate copolymers having molar composition ratios 112/1, 26/1, 7.7/1, and 2/1, has demonstrated that the stabilization of poly(methyl methacrylate) by copolymerized methyl acrylate is due to inhibition of the depolymerization initiated at terminally unsaturated structures, probably by direct blockage by methyl acrylate units. The molecular weight of the copolymers decreases rapidly during degradation, suggesting that a random scission process is involved. The products of degradation consist of the monomers, carbon dioxide, chain fragments larger than monomer, and a permanent gas fraction which is principally hydrogen. Infrared and ultraviolet spectral measurements suggest that the residual polymer, which is colored, incorporates carbon–carbon unsaturation. The complete absence of methanol among the products is surprising in view of its abundance among the products of degradation of poly(methyl acrylate). These observations have been accounted for qualitatively in terms of acceptable polymer behavior.
Thermal degradation of copolymers of methyl methacrylate and methyl acrylate. II. Chain scission and the mechanism of the reaction
Authors: Grassie N. , Torrance B. J. D. 
Published: April 2003

AbstractIt has been established that one molecule of carbon dioxide is produced for each chain scission during degradation of methyl methacrylate–methyl acrylate copolymers with molar compositions in the ratios 112/1, 26/1, 7.7/1, and 2/1. Thus the relatively simple measurement of the production of carbon dioxide can be used to determine the extent of chain scission. In this way the relationships between chain scission and volatilization, zip length, copolymer composition, and the production of permanent gases have been established. The rate of chain scission is proportional to a power of the methyl acrylate content of the copolymer less than 0.5, from which it has been concluded that a significant proportion of the initial production of radicals and the subsequent attack of these radicals on the polymer chains is at random and not specifically associated with the methyl acrylate units. A mechanism for the overall thermal degradation process in this copolymer system is presented in the light of these observations.
Anionic copolymerization of 1,1‐diphenylethylene and 2,3‐dimethylbutadiene
Authors: Yuki Heimei , Hatada Koichi , Inoue Tadanori 
Published: April 2003

Abstract1,1‐Diphenylethylene (M2) and 2,3‐dimethylbutadiene (M1) were copolymerized with n‐butyllithium in tetrahydrofuran. The rate of consumption of each monomer was followed by the change of high resolution NMR spectra of the reaction mixture. The copolymerization proceeded alternately, if the ratio of initial monomer concentrations, [M2]0/[M1]0, was sufficiently larger than unity. By assuming the rate constant k22 to be zero, the constants k21 were obtained from the consumption rates of the monomers. In the alternating copolymerization, 2,3‐dimethylbutadiene was incorporated into the copolymer only as the 1,4‐structure, while the 1,2‐structure was predominant in homopolymerization.
Syntheses of aromatic polyketones and aromatic polyamide
Authors: Iwakura Y. , Uno K. , Takiguchi T. 
Published: April 2003

AbstractHigh molecular weight aromatic polyketones were prepared from p‐ and m‐phenoxybenzoic acid in polyphosphoric acid by heating the reaction mixture at 100°C. High molecular weight aromatic polyamide was derived from the polyketone obtained through Schmidt reaction or Beckmann rearrangement. The polyamide obtained by Schmidt reaction was found to have some regularity in an arrangement of its repeating units. The thermal stability of the polyketone and the polyamide were good.
Polyhydrazides. I. N‐alkylated polyhydrazides from diesters and hydrazine
Authors: Iwakura Yoshio , Uno Keikichi , Hara Shigeyoshi , Kurosawa Shigeru 
Published: April 2003

AbstractN‐Alkylated polyhydrazides containing 1,3,4‐oxadiazole linkages in them were prepared by solution polycondensation of dicarboxylic acid diesters with hydrazine in fuming sulfuric acid or polyphosphoric acid. Their preparation, characterization, and some physical properties are described.
Electron‐transfer polymers. XXXVII. Preparation and redox behavior of polycarbonates with incorporated hydroquinone units
Authors: Wegner Gerhard , Nakabayashi Nobuo , Duncan Stephen , Cassidy Harold G. 
Published: April 2003

AbstractPreparation of polycarbonates from a quinonediol and phosgene, and from the quinonediol and various bischloroformates, is described. Some of the bischloroformates were prepared from poly(ethylene oxides) with two terminal hydroxyl groups by phosgenation. The quinone groups incorporated into the polymer chain were reduced to hydroquinone groups. Some of these polymers were titrated oxidatively in 90% acetic acid. Their redox behavior cannot be described by a simple Nernst equation. It is assumed that the differences between theoretically expected and experimentally obtained potentials express the amount of work needed to reshape the polymer coil according to a thermodynamically stable distribution of the redox groups.
Optical studies of the stress‐induced crystallization of rubber
Authors: Yau W. , Stein R. S. 
Published: April 2003

AbstractThe low‐angle light scattering by films of stretched natural and synthetic rubbers was investigated. Intense Vv scattering is found under conditions when crystallization occurs which is characteristic of the scattering from aggregates of dimensions comparable with the wavelength of visible light. These were identified with the γ fibrils described by Andrews. The dependence of scattering was studied as a function of light polarization direction, orientation direction, elongation, temperature, degree of swelling, type of swelling liquid, and degree of crosslinking. It was concluded that the scattering unit consists of an assembly of crystals with their chain axes parallel to the stretching direction, but (in the case of natural rubber at high elongations) with the fibril axis at a slight angle to the stretching direction. The scattering is not affected much by swelling but is decreased upon increasing the temperature. Upon recooling the scattering returns, but does so over several hours, indicating that much of the scattering arises from secondary crystallization.
Stress relaxation of monodisperse poly‐α‐methylstyrene
Authors: Fujimoto Teruo , Ozaki Noriyoshi , Nagasawa Mitsuru 
Published: April 2003

AbstractThe viscoelastic properties of monodisperse poly‐α‐methylstyrenes of molecular weights of 4 × 104 to 50 × 104 were studied by the tensile stress‐relaxation method. The relaxation‐time spectra as well as the steady‐flow viscosity, the steady‐state compliance, the maximum relaxation time, and the modulus associated with the maximum relaxation time were determined. The molecular weight dependences of these quantities were compared with the theory of Rouse and Bueche as modified by Ferry, Landel, and Williams, as well as with data on other polymers reported in the literature.
Dimensional stability of regenerated cellulose film in relation to orientations of crystalline and noncrystalline phases
Authors: Takahara Hirokazu , Nomura Shunji , Kawai Hiromichi , Yamaguchi Yutaka , Okazaki Kazumi , Fukushima Akio 
Published: April 2003

AbstractThe dimensional stability of regenerated cellulose film on swelling with water is discussed in relation to the biaxial orientation of the two kinds of structural units, cellulose II crystallites and noncrystalline chain segments, and their anisotropic swelling (anisotropic absorption of water). Considerable dimensional stability in the plane of the film but enormous instability of thickness on swelling in water of some commercial cellophanes is qualitatively interpreted in terms of the planar orientation of crystal (101) planes along the film surface and the orientation of the noncrystalline chain segments parallel to the film surface. The dimensional changes on swelling from the completely dry state to 10% moisture regain were further interpreted quantitatively in terms of the degrees of biaxial orientation of the two kinds of structural units and their degrees of anisotropic swelling by modifying the Hermans monophase model for crystalline and noncrystalline biphase structures. The following degrees of anisotropic swelling of the structural units were thus obtained: qc, [101] = 0.40%, qc, [101] = −0.33%, and qa = 2.42%.
Effect of morphology in the surface region of polymers on adhesion and adhesive joint strength
Authors: Schonhorn Harold , Ryan Frank W. 
Published: April 2003

AbstractThe morphological character of the surface region of polyethylene has been considered with respect to adhesion and adhesive joint strength. By melting polyethylene onto a high‐energy surface (e.g., aluminum) we have provided for extensive nucleation and the formation of a transcrystalline region in the polymer. Dissolution of the metal rather than peeling the metal from the polymer leaves the surface region of the polymer intact. The polymer sheet is now amenable to conventional adhesive bonding and forms a strong adhesive joint. We conclude from this study that the occurrence of the normal weak boundary layer is a consequence of the morphology of the surface region of the material and is, therefore, influenced by the method of preparation.
Network relaxation properties of crosslinked poly(ethyl acrylate) and polydimethylsiloxane in the rubbery plateau region
Authors: Sperling L. H. , Tobolsky A. V. 
Published: April 2003

AbstractThe stress relaxation properties of poly(ethyl acrylate) and polydimethylsiloxane were investigated under conditions where oxidative degradation was minimized. The relaxation observed is thought to result from the continued approach to equilibrium of the network chains with cooperative thermal motion. These elastomers, representing two new classes of polymer, and two new types of crosslinking, were found to behave surprisingly like natural rubber and butadiene–styrene copolymer. Relaxation was found to obey a power law in time, with a negative exponent of 0.22 for both polymers.
Liquid–liquid phase separation in multicomponent polymer solutions. III. Cloud‐point curves
Authors: Koningsveld R. , Staverman A. J. 
Published: April 2003

AbstractCloud‐point curves (CPC) were calculated on the basis of the Flory‐Huggins free‐energy relation for various hypothetical polymer samples dissolved in a single solvent. Molecular weight distributions varying widely in shape and width were examined. The shape of the CPC reflects details of the molecular weight distribution. This appears from the location of the critical point on the right‐hand branch of the CPC. The latter often shows a depression, which becomes more distinct as the Mz/Mw value increases. These theoretical results were confirmed experimentally with the system polyethylene–diphenyl ether. With the aid of the theoretical data collected it was possible to explain the remarkable agreement between the θ temperatures determined by light‐scattering and by the Shultz‐Flory method. The latter method is basically incorrect, since it identifies the polymer solution with a binary mixture. An explanation could also be given for the empirical relation which McIntyre et al. recently found between the shape of the top of the CPC and the width of the molecular weight distribution.
Secondary processes of poly(methyl methacrylate) and their activation energies as determined by shear and tensile creep compliance measurements
Authors: Thompson Edward V. 
Published: April 2003

AbstractThe results of measurement of the shear and tensile creep compliance of poly(methyl methacrylate) between −150 and 75°C. are presented. The master curves show the creep behavior from essentially elastic response to the onset of the α‐process. The logarithmic retardation spectra and shear loss compliance reveal two molecular processes, one process being partially obscured by the α‐process and therefore not as well defined as the other. These processes manifest themselves as breaks in an Arrhenius plot of the shift factors at about −35 and +25°C. The activation energies in the −35 to 25°C. and 25 to 80°C. ranges are 17.8 kcal./mole and 42.2 kcal./mole, respectively. The former temperature range and activation energy corresponds to the well‐known ß‐process in poly(methyl methacrylate), the latter to a process which is apparently detectable using various long‐time experimental techniques but whose molecular interpretation is at present obscure. The activation energy in the −150 to −35°C. range is about 8.7 kcal./mole.
On the possibility of chain folding in solutions of normal paraffins and polyethylene
Authors: Liu Kang‐Jen , Ullman Robert 
Published: April 2003

AbstractA simple statistical thermodynamic argument is presented in which the probability of intramolecular chain folding of normal paraffins and polyethylene in solution is examined. This possibility is based on the existence of low‐energy intramolecular conformations which are stable enough to overcome the tendency of a chain molecule to assume a random arrangement in solution. Some rough estimates of the magnitudes of energetic interaction in straight‐chain hydrocarbons are made to demonstrate the plausibility of this hypothesis. The experimental support for this model arises from NMR spectra of normal paraffins in aromatic hydrocarbon solvents.
Electronic and ionic conductivity in nylon 66
Authors: Seanor D. A. 
Published: April 2003

AbstractThe conductivity of dry poly(hexamethylene adipamide) (nylon 66) was measured as a function of time and temperature. Three temperature ranges were observed in which the time dependence of conductivity differed: (a) below 80°C. the conductivity decreased continuously with time; (b) between 80°C. and 110°C. the conductivity remained constant over long periods; (c) above 120°C. a continuous decrease in conductivity was again observed. In other experiments the volume of gas evolved from the nylon film was measured under continuous potential and compared with the total current passed through the sample. It was observed that above 120°C. the gas evolved corresponded to about one‐half the volume calculated if the conduction process involved only protons. Below 120°C. the gas evolved corresponded to an increasingly small fraction of the total current until below 90°C. no evolution of gas was observed. This suggests that at temperatures above 120°C. conduction involves the transport of both protons and electrons, whereas at lower temperatures it is electronic. Mechanisms of conduction are discussed.
Variation of polymer chain dimensions with temperature below the theta point
Authors: Orofino T. A. 
Published: April 2003

AbstractThe temperature dependence of the intrinsic viscosity [η] for the system polystyrene‐cyclohexane in the interval −20 < (T − ψ) ≤ 0 near the ideal temperature ψ has been investigated. The observed diminution in size of the molecular coil with decreasing temperature is attributable to attractive net polymer‐solvent interactions, denoted by negative values for the excluded volume parameter z. The data thus comprise an interesting selection for comparison with the predictions of various excluded volume theories. Among the approximate, closed‐form expressions the functional relationship of Flory (x5 − α3 ∼ z) appears to describe best the variation of [η] with temperature in the region examined. The behavior of the Huggins constant k′ derived from the intrinsic viscosity plots is also examined, in accordance with the Peterson‐Fixman model, suitably extended to the temperature region below ψ.
Magnetic bearing torsional creep apparatus
Authors: Plazek Donald J. 
Published: April 2003

AbstractA torsional creep and recovery apparatus has been designed and constructed to measure extremely wide ranges of recoverable creep compliance (10−10 to 10−2 cm.2/dyne) and viscosity (10−1 to 1016 poises) within the temperature range −60 to 220°C. Friction is avoided by supporting the moving element, the rotor, in a magnetic field, inducing the required torque with a drag cup motor, and monitoring the angular displacement with a light lever and a light following recorder. Measurements of recoverable compliance can be made further into the region of time scale which is dominated by viscous deformation than has been heretofore possible. In situ sample manipulation of viscoelastic liquids is utilized. Measurement is made on liquid cylinders between circular stainless steel platens. Results which have been obtained on a 1.22 × 105 molecular weight polystyrene are presented to illustrate the range of possible measurements and to indicate the value of such results covering up to six logarithmic decades of time scale.
γ–α Solid–solid transition of isotactic polypropylene
Authors: Pae K. D. 
Published: April 2003

AbstractX‐ray diffraction patterns have been taken as a function of time and temperature on a sample of polypropylene held under high pressure (4.14 kbar) for 180 hr. at a temperature of 248°C. and subsequently cooled to room temperature. The molded sample initially crystallizes in the triclinic γ–phase but transforms to the γ–phase at elevated temperatures. The rate of conversion from γ to α is a function of time and temperature and tends to approach a constant value with increasing time. The nature of the thermal changes occurring in the sample was also studied by differential scanning calorimetry. It appears that at low scan speeds, there is a solid–solid transformation from the α‐phase to the γ–phase, but at high scan speeds, the γ–phase melts without conversion to the α‐phase.
Temperature dependence of the bulk crystallization rate of polymers
Authors: Kim H. , Mandelkern L. 
Published: April 2003

AbstractData already existing in the literature for the overall crystallization kinetics of a variety of polymers have been analyzed according to different possible nucleation mechanisms. The conclusions reached are similar to those previously deduced from an examination of ata for spherulite growth rates. It is demonstrated that, if allowed a reasonable choice for the equilibrium melting temperature, no unbiased selection of a unique nucleation process can be made. Moreover, a set of universal parameters exists for each of the nucleation and growth processes considered which allows the data for all polymers to be represented by a single straight line. The only quantities that are unique to a given polymer are the equilibriun melting temperature and the activation energy for transport.
Phase relationships and thermodynamic interactions in isotactic polypropylene–diluent systems
Authors: Nakajima Akio , Fujiwara Hiroshi 
Published: April 2003

AbstractPhase relationships of isotactic polypropylene in various organic diluents were investigated. The diluents used were aliphatic alcohols, alkyl phenols, aryl phenols, diphenyl derivatives, alkyl aryl ethers, esters, and others. Among the diluents examined, n‐butyl alcohol, p‐tert‐butyl phenol, p‐tert‐amyl phenol, diphenyl, diphenyl ether, benzyl phenyl ether, dibenzyl ether, and benzyl propionate were found to be theta solvents for isotactic polypropylene at temperatures in the range 120–190°C. For these theta solvents, the thermodynamic interaction parameters were determined. The results are discussed in relation to the type of diluent.