bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization during crystallization of selenium
Authors: Coughlin Michael C. , Wunderlich Bernhard 
Published: April 2003

AbstractThe crystallization of selenium from the melt has been studied as a function of time at 90, 126, and 200°C by following the density and the concentration of Se8 rings. The crystallization is shown to involve crystallization of the polymeric species in the melt and, especially at later stages of the crystallization, crystallization during polymerization. A kinetic scheme has been developed which permits the description of the experimental data.
Relative rates of creep and relaxation in shear, elongation, and isotropic compression
Authors: Markovitz Hershel 
Published: April 2003

AbstractThe relative rates of relaxation and creep in shear, elongation, and isotropic compression are discussed in terms of the theory of linear viscoelasticity. Exact expressions are given for the creep rates; for the relaxation rates approximations are found which are useful in the glassy range where the amount of relaxation is small. Among the results of interest is the relation:

valid if d In B/d In t is less than d In J/d In t as is intuitively expected and experimentally found. Here J(t), E(t), and B(t) are the shear, tensile, and bulk creep compliances, respectively. For polymers in the rubbery and flow regions, (d In J/d In t)/(d In D/d In t) is very close to 1(usually within 0.01%); in the glassy region, it is unlikely to be greater than 1.2.
Generalized characterization of relaxation properties and high elasticity of polymeric systems
Authors: Isayev A. I. 
Published: April 2003

AbstractMeasurements of apparent viscosity, normal stress coefficient, and storage and loss moduli have been used to determine the characteristic relaxation time. The ratio of the characteristic relaxation time θin corresponding to a given deformation rate ˙γ to that of the initial state θe is found to be a function of ˙γθin. For a wide range of polymeric systems, the ratio of normal stress to the initial high elasticity modulus and to the high elastic deformation γe are the same function of ˙γθin. It has been established that γe, like other viscoelastic characteristics of polymer systems, is determined by the relaxation properties and their variation due to deformation. The dependence of γe on θe/θin is common to a wide range of polymeric systems. The generalized characteristics were independent of the nature of the polymeric chain, molecular weight, molecular weight distribution, temperature, polymer concentration in solution, and solvent type. These results allow us to describe approximately normal stresses and high‐elastic deformations as functions of shear rate and storage and loss moduli as functions of frequency, if we know θin the relation between shearing stress and shear rate.
The nature of dielectric losses in H‐Film
Authors: Wrasidlo W. J. 
Published: April 2003

AbstractBased upon the high‐temperature solid‐state dielectric behavior of H‐Film and supporting evidence from infrared spectroscopy, heat capacity, thermal expansion, and dynamic mechanical measurements, it is concluded that the actual chemical structure of H‐Film is far more complex than previously expected. The very unusual thermal properties of this polymer, such as lack of a glass transition temperature, its extreme insolubility, and high dielectric losses above 250°C with only weakly corresponding mechanical losses, suggest that in addition to the pyromellitimide repeat unit, a significant part of the structure consists of amide groups, probably in the form of crosslinks.
Carbon‐13 spin‐lattice relaxation study of linear polymers in solution
Authors: Inoue Yoshio , Nishioka Atsuo , Chûjô Riichirô 
Published: April 2003

AbstractProton‐decoupled, partially relaxed, Fourier‐transform NMR of 13C in natural abundance was used to determine spin‐lattice relaxation times of individual carbons of polyisobutylene, polyacrylonitrile, poly(vinyl chloride), and poly(vinyl alcohol) in solution. It is shown that the relaxation times are independent of the difference in stereochemical configuration. From the values of the nuclear Overhauser enhancement factor it is shown that the relaxation times are independent of the difference in stereochemical configuration. From the values of the nuclear Overhauser enhancement factor it is shown that the excess spin energy from equilibration of all the 13C, even of quaternary carbons, in the polymers dealt with here is transferred to the lattice mainly through 13C‐1H dipolar interactions. It is shown that the segmental motions responsible for the spin‐lattice relaxation of the polymer skeleton in solution can be described by the isotropic model within a good approximation, except for poly(vinyl alcohol) at low temperature. The activation energies of skeletal and internal methyl motions are estimated from the temperature dependence of the correlation time. Differences in the 13C line widths for individual carbons of polyisobutylene are discussed briefly.
Energy storage in drag‐reducing polymer solutions
Authors: Kohn Michael C. 
Published: April 2003

AbstractA new theory, which relates viscous drag reduction to the energy stored by polymer molecules subjected to a fluctuating wall shear rate, is proposed for the origin of the Toms effect. The strain energy densities of several polymer solutions were estimated from bead‐spring theory. The requisite molecular polymers were optimized by a least‐squares fit of calculated to observed intrinsic viscosities. Friction reduction was found to be a monotonic function of the strain energy density for a given polymer–solvent combination. The correlation was independent of molecular weight and concentration for pipes of 0.5–2.0 in. diameter. Differences between the points of onset of drag reduction for different polymer–solvent combinations may be due to the unequal effect of internal viscosity.
Thermal fracture of plastics
Authors: Cross A. , Haward R. N. 
Published: April 2003

AbstractThe extension and fracture under tension of poly(vinyl chloride) strips of different lengths have been studied. It was found that, in spite of decreasing strain rate, long pieces are subject to a type of brittle fracture (necking rupture) occurring immediately after neck formation. This result, which could be expected from previous work, is shown to depend on the elastic energy stored in the longer test pieces. This energy is converted to heat under conditions of neck formation, leading to a temperature rise of 24 ± 4°C, determined by a thermal imaging system. With short test pieces the rise in temperature is much smaller, and a transition to stable neck propagation occurs. Optical and electron micrographs provide additional evidence of heating at the fracture surface. A semiquantitative treatment of the adiabatic process gives upper and lower limits for the predicted temperature change neglecting thermal losses. It is also possible to estimate a minimum length for the initiation of adiabatic deformation. Both calculations give results in reasonable agreement with experiments. Observations with polycarbonate show a similar length effect at low temperatures.
Crystallization‐induced reactions of copolymers. IV. Ester‐interchange reorganization of poly(ethylene terephthalate‐co‐2‐methylsuccinate)
Authors: Lenz R. W. , Go S. 
Published: April 2003

AbstractThe application of ester‐interchange reactions to the crystallization‐induced reorganization of random to block copolymers, which was demonstrated in the previous paper of this series, was followed quantitatively in this investigation. Structural changes based upon dyad compositions in copolyesters of terephthalic acid and 2‐methylsuccinic acid with ethylene glycol were determined by high‐resolution NMR. Sequence length distributions so calculated were related to the effects of copolymer composition, catalyst concentration, and reaction temperature on the rate of the ordering process and to the effect of structure on crystalline properties.
Simultaneous polymerization and formation of polyacetylene film on the surface of concentrated soluble Ziegler‐type catalyst solution
Authors: Ito Takeo , Shirakawa Hideki , Ikeda Sakuji 
Published: April 2003

AbstractA direct method of simultaneously polymerizing and forming acetylene monomer to produce uniformly thin films of polyacetylene was investigated in terms of catalyst system, catalyst concentration, and polymerization temperature. The best catalyst was a Ti(OC4H9)4–Al(C2H5)3 system (Al/Ti = 3–4) and the critical concentration was 3 mmole/l. of Ti(OC4H9)4. Below the critical concentration, only a solid or a powder was obtained. The configuration of the polymers obtained depends strongly upon the polymerization temperature. Thus an all‐cis polymer was obtained at temperatures lower than −78°C, whereas an all‐trans polymer resulted at temperatures higher than 150°C. Observations either in an electron microscope by direct transmission or in a scanning electron microscope showed that the film is composed of an accumulation of fibrils about 200–300 Å in width and of indefinite length.
Photoreactions of N‐vinylcarbazole induced by metal salts. II. Further studies on the photocationic polymerization sensitized by sodium chloroaurate(III) in nitrobenzene
Authors: Asai Michihiko , Tazuke Shigeo , Okamura Seizo 
Published: April 2003

AbstractFurther investigations of the photopolymerization of N‐vinylcarbazole(VCZ) sensitized by sodium chloroaurate(III) in nitrobenzene were undertaken under irradiation of near‐ultraviolet light at 30°C. Copolymerization with isobutyl vinyl ether and the kinetic behavior of polymerization were studied. These propagation and chain‐breaking features were discussed in comparison with those obtained in the thermal polymerization. Electron spin resonance spectroscopy was conducted at 77°K in various systems.
Radiation‐induced emulsion polymerization of ethylene. II. Effect of potassium myristate concentration and dose rate on the rate of polymerization in connection with polymer properties, kinetics, and mechanism
Authors: Senrui Shiro , Suwa Takeshi , Takehisa Masaaki 
Published: April 2003

AbstractRadiation‐induced emulsion polymerization of ethylene with potassium myristate as an emulsifier was studied in connection with the kinetics and the mechanism. The molecular weight of polymer was relatively low, of the order of 103, when a sufficient amount of emulsifier was used. However, polyethylene gel was produced in the absence of a sufficient amount of emulsifier. The rate of polymerization was proportional to the 0.5 power of dose rate and increased slightly with increasing emulsifier concentration. The rate of seeded polymerization followed a similar trend to that for conventional polymerization. Kinetic analysis of these results suggests that the escape of radicals produced by chain transfer of propagating radical with the emulsifier and the monomer from polymer particles into the aqueous phase plays an important part in the rate of polymerization. The melting temperature and the crystallinity of the polymer significantly decreased with increasing polymerization temperature in the range 40–60°C.
Radiation‐induced emulsion polymerization of ethylene. III. Emulsion polymerization with ammonium perfluorooctanoate as the emulsifier
Authors: Senrui Shiro , Suwa Takeshi , Takehisa Masaaki 
Published: April 2003

AbstractRadiation‐induced emulsion polymerization of ethylene with ammonium perfluoro‐octanoate as an emulsifier was studied in order to elucidate the effect of the number of polymer particles. Owing to the stable structure of the emulsifier from a radical attack, no CF bond was detected in the polyethylene as expected. The polyethylene produced was mostly gel containing a small amount of low molecular weight polyethylene. This may be attributable to chain transfer to the polyethylene. The effects of dose rate and of concentration of the emulsifier were determined without considering the chain‐transfer reaction to the emulsifier. By considering the escape of the radical which is produced by chain transfer to the monomer from the polymer particle to the aqueous phase at the steady state, the following equation is derived:

The experimental results could be explained by this equation, and the apparent rate constants were obtained.
Anionic polymerization initiators containing protected functional groups and functionally terminated diene polymers
Authors: Schulz D. N. , Halasa A. F. , Oberster A. E. 
Published: April 2003

AbstractOrganolithium reagents substituted with hydroxyl‐carrying mixed acetals (i.e., tetra‐hydropyranyl and α‐ethoxyethyl ethers) have been prepared in high yields and used to polymerize 1,3‐butadiene to various acetal‐terminated polybutadiene polymers. A method is described for converting acetal‐containing polymers into hydroxyl‐containing polymers. The polybutadienes have been characterized with regard to endgroup types, quantitative functionalities, molecular weights, molecular weight distributions, and microstructures. Dihydroxyl terminated polymers are prepared anionically in the absence of gel. Such materials are more suitable from the standpoint of f(OH) and M̄w/M̄n for chain extension studies than are prepolymers prepared by radical methods.
Reaction of polyamine polymer with molecular iodine via charge‐transfer complex formation
Authors: Tomono Tsugikazu , Hasegawa Etsuo , Tsuchida Eishun 
Published: April 2003

AbstractThe reaction of a Mannich base type‐polyamine polymer with iodine (I2) was studied kinetically and thermodynamically in order to clarify the polymer effects in the formation of triiodide ions (I3−). N,N‐Dimethyl‐p‐(4‐methylpiperazinomethyl) aniline and 1,4‐dimethylpiperazine were used as low molecular weight donor model compounds. Triiodide ions are produced from the polyamine–I2 system immediately after mixing the two‐component solutions, while in the systems with I2 and N,N‐dimethyl‐p‐(4‐methyl‐piperazinomethyl)aniline and 1,4‐dimethylpiperazine they are obtained only when relatively high concentrations of both donor and acceptor solutions were mixed. This is explained by the entropic contributions of the polymer chain such as the stacking effect of donor nitrogen atoms, i.e., the increment of local donor concentration around I2 in the reaction field. The relation between the solution behavior of the reaction systems and the rate of formation of I3− ions also supports this kind of polymer effect. The effects of neighboring groups and dielectric constant on the reaction are also discussed.
Processability characteristics of chlorinated poly(vinyl chloride)
Authors: Krishnan M. , Singh Parkash , Thampy R. T. , Gupta V. B. 
Published: April 2003

AbstractChlorinated poly(vinyl chloride) (CPVC) is known to have a higher softening temperature than conventional poly(vinyl chloride) (PVC). Its processability characteristics are, however, different; it has been reported that CPVC is more difficult to process. However, only limited information on the processability characteristics is available. This paper describes some studies of the flow behavior of CPVC melts in a capillary rheometer. The true melt viscosity and activation energy were determined between 190° and 210°C for a number of samples, and they appear to be related to the cohesive energy density of the samples. It was observed that melt fracture, i.e., gross distortion of the extrudate, occurs even at low shear rates in samples having a high chlorine content. This has been attributed to the relatively high pressures that have to be used, the pronounced non‐Newtonian nature of the melt, and melt elasticity. It is postulated that melt elasticity could result from crosslinking at the site of the double bond which is known to be formed by dehydrochlorination.
Formation and flocculation of graft copolymer micelles
Authors: Horii Fumitaka , Ikada Yoshito , Sakurada Ichiro 
Published: April 2003

AbstractCriteria for formation and flocculation of micelles from pure graft copolymers were investigated in single selective solvents by turbidimetry with the use of two series of graft copolymers from poly(vinyl acetate) (PVAC), i.e., PVAC–styrene graft copolymers with one branch and PVAC–methyl methacrylate graft copolymers with one and several branches. These graft copolymers could be completely coagulated through two processes in the selective solvents which had widely different ⊖ temperatures. The first process is the formation of micelles. One sequence, i.e., either backbone or branch of the graft copolymers, becomes desolvated under conditions similar to those for the corresponding homopolymer. This results in formation of the core of the micelle, the other soluble sequence extending from the surface of the core into the solvent phase. As the soluble chains cover the micelle core, no macroscopic phase separation occurs, but a stable dispersion is formed. The second process is that the micelle becomes too unstable to exist as dispersed when the solvency of the medium for the soluble sequence decreases to a certain degree. As a result, flocculation of the micelle finally takes place.
Effect of chain interpenetration on polymer–polymer interaction in solution
Authors: Worsfold D. J. 
Published: April 2003

AbstractTwo series of monodisperse polystyrenes have been prepared with a molecular weight range of 3,000 to 300,000. One series was lightly substituted with dimethylbenzylamine groups, the other with 2,6 dinitro‐4‐benzoyloxyphenol groups. Members of each series were dissolved together in benzene solution in the range of 0.1–30%, and the equilibrium constant for the formation of the ammonium phenolate ion pair measured. Also measured was the corresponding equilibrium constant between comparable small molecular weight analogs, and between these analogs and the substituted polymers. The degree of association found between the models and between the models and the polymers was independent of molecular weight, but deviations were found in the polymer–polymer interaction. Normal equilibrium constants were found at high polymer concentrations indicating that chain interpenetration occurred freely. At low concentrations of polymer, if several links per chain were possible it was found an excess of linkages were formed. If only one link per chain was possible, low degrees of association were found for high molecular weight polymers, but the effect was not as large as a consideration of excluded volumes on a spherical model would predict.
Synthesis of polymers by using divalent metal salts of mono(hydroxyethyl) phthalate: Metal‐containing polyurethanes
Authors: Matsuda Hideaki 
Published: April 2003

AbstractAs difunctional compounds containing an ionic bond in the molecule, divalent metal salts (I) of mono(hydroxyethyl) phthalate were prepared in high purity and high yield. Mg and Ca were selected as divalent metal.
magnified imageMetal‐containing polyurethanes containing ionic links in the main chain were synthesized by the polyaddition reaction of I or, I–glycols with diisocyanates. The polyurethane obtained were glassy materials or white powders, depending on the species of diisocyanates and glycols. Close agreement between observed and calculated values of metal content of the polyurethanes were obtained. The viscosities (in dimethyl‐formamide) of the polyurethanes decreased markedly with increasing of metal content. Moreover, the decomposition temperatures were lowered by introduction of metals into the polyurethanes. However, the decomposition rates of metal‐containing polyurethanes were lower than those of polyurethanes not containing metal.
Synthesis of polymers by using divalent metal salts of mono(hydroxyethyl) phthalate: Metal‐containing polyurethane‐ureas
Authors: Matsuda Hideaki 
Published: April 2003

AbstractA series of metal‐containing polyurethane‐ureas containing ionic links in the main chain was synthesized by the polyaddition reaction of hexamethylene diisocyanate with mixtures of metal salts of mono(hydroxyethyl) phthalate and bisureas containing two hydroxyl groups which were obtained from monoethanolamine and diisocyanates. The polyurethane‐ureas obtained were generally yellowish powders or solids. Close agreement between observed and calculated values of metal content of the metal‐containing polyurethane‐ureas was obtained. The viscosities (in dimethylformamide) of polyurethane‐ureas decreased markedly with increase of metal content. Moreover, the decomposition temperatures were lowered a little by introducing metals into the polyurethane‐ureas. Dimethylformamide, m‐cresol, and dimethyl sulfoxide were comparatively good solvents for the metal‐containing polyurethane‐ureas; however, the polymers were insoluble in all other solvents.
Radiation degradation of poly(2‐methylpentene‐1 sulfone)
Authors: Bowden M. J. 
Published: April 2003

AbstractPoly(2‐methylpentene‐1 sulfone) underwent random chain scission upon exposure to 1 MeV electron irradiation followed by extensive depropagation from the broken ends of the chain. Above 100°C, both sulfone and aliphatic peaks in the infrared spectrum disappeared at equal rates. An investigation of the kinetics suggested that the chains completely unzip. Below 100°C the initial rate of loss of SO2 was faster than loss of the aliphatic moiety.
Reactions and wetting properties of 1:1 perfluoroalkyl allyl and methallyl ether–maleic anhydride copolymers
Authors: Pittman A. G. , Wasley W. L. , Sharp D. 
Published: April 2003

AbstractPolymers with fluoroalkyl side‐groups on three of every four carbon atoms along the polymer main chain were made by treating 1 : 1 copolymers of perfluoroallyl (or methallyl)ethers and maleic anhydride with SF4, and then esterifying the resulting acid fluoride groups with 1H, 1H‐pentadecafluorooctanol. Surface wettability of these polymers by polar and non‐polar liquids was studied. The critical surface tension (γc) was found by Zisman's method. The dispersion force component of polymer surface energy (γsD) and the polar component of surface energy (γsp) were calculated by the respective methods of Fowkes and Owens. The γc values for several of the highly fluorinated polymers were lower than previously reported for any fluoropolymer but not so low as has been observed for the surface of an oriented perfluoroacid monolayer. In the range 11.4–18.5 dyne/cm, γc approximates γsD for the fluorinated surfaces; however at lower γc values, considerable difference between γc and γsD was noted.
Poly‐1‐acryloylbenzotriazole as polyester and polyacrylamide precursor
Authors: Ferruti Paolo , Feré Angelino , Cottica Giovanni 
Published: April 2003

Abstract1‐Acryloylbenzotriazole was prepared and polymerized. The resulting poly‐1‐acryloylbenzotriazole gave pure polyacrylic esters and polyacrylamides by reaction under mild conditions with alcohols and amines.
High temperature polymers. II. High temperature polymers from 4,4′‐[sulfonylbis‐(p‐phenyleneoxy)]dianiline
Authors: Brode George L. , Kawakami James H. , Kwiatkowski George T. , Bedwin Albert W. 
Published: April 2003

AbstractNovel aromatic diamines have been prepared which contain an ordered sequence distribution of thermally stable, flexible, or rigid units. The synthesis of these materials involves a nucleophilic displacement reaction in aprotic solvent with, for example, the alkali metal salt of p‐aminophenol, optionally, the salt of a bisphenol and an activated aromatic halide. Such monomers are useful “building blocks” for various polymeric systems but are of special interest in those which can benefit from the high glass transition temperature imparted by polar or rigid moieties, together with improved impact properties conveyed by either groups. Polyimides and polyamide‐imides are examples and display high heat distortion temperatures, good solvent resistance, excellent mechanical properties, high thermal and oxidative stability and depending on diamine structure and molecular weight, thermoplastic characteristics. The synthesis and properties of polyamides, polyimides and polyamide‐imides based on 4,4′‐[sulfonylbis(p‐phenyleneoxy)] dianiline are presented in this paper.