bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation by mechanical action as a means of studying cellulose‐water interaction
Authors: Leopold B. , Fujii J. S. 
Published: June 2010

AbstractA number of samples containing varying amounts of lignin, xylan, and glucomannan were prepared from spruce wood and subjected to vibratory ball‐milling m water, methanol, and benzene. The results support the idea that the main factor determining the extent of cellulose degradation by mechanical action is the plasticity of the substrate It was found that the presence of lignin greatly increases the extent of degradation probably as a result of mechanical restriction of the deformability of the system. On the other hand, glucomannan reduces the extent of degradation, while xylan has little or no effect. This is believed to be due to the location of part of the glucomannan inside the microfibril, where it is able to facilitate the penetration of water. Xylan is located on the outside of the fibril where a similar effect could not occur. It m also shown that the moisture regain of the samples varies with the hemicellulose content, but that the contribution of the glucomannan is less than that of the xylan This indicates that the mobility of the glucomannan molecule is restricted, presumably by its close association with the cellulose in the microfibril.
Quantitative studies of ringed spherulite deformation in polyethylene films
Authors: Moore Robert S. , Gieniewski Chester 
Published: June 2010

AbstractCreep and creep recovery experiments were carried out on films of linear polyethylene containing ringed spherulites. Photographic light‐scattering patterns obtained during the experiments from the rings and spherulites were analyzed to determine the quotient of the extension ratio in the direction of stress to that at right angles to the stress direction, Xy/γz. Comparison with results derived from mechanical strain measurements indicated stronger time dependencies of creep and creep recovery as measured by light scattering than as determined from mechanical strain measurements for a sample of Marlex 6035 crystallized at 105°C. The results arc interpreted in terms of a model of spherulite response which incorporates chain tilting. The probable dependence of the deformation process on the crystallization conditions and the type of deformation experiment is pointed out.
Multiple phase transitions of polybutene‐1
Authors: Geacintov C. , Miles R. B. , Schuubmans H. J. L. 
Published: June 2010

AbstractMultiple phase transitions of polybutene‐1 in the form III modification have recently been the subject of discussion by a number of authors. The exact nature of the observed phenomena has remained in doubt, leading to the proposal of divergent theories. Differential thermal analyses and x‐ray diffraction studies of polybutene‐1 in the form III modifications have shown that the nature of the phase transformations is a function of the heating rate. At very slow heating rates (1°C./day), an apparent form III to form I' crystal‐crystal transformation, believed to be related to a thermodynamic “selection” process, has been observed. At faster heating rates (0.2–0.3°C./min.), only part of the form III modification is able to undergo the transformation to form I' the remainder undergoes a melting transition at 96°C, followed by immediate recrystallization to form II. The form I' generated in this process melts at 100°C, and also recrystallizes to the form II modification. At very fast heating rates (20–50°C./min.), form III melts at 96°C, failing to recrystallize.
Theory of relaxation phenomena associated with the molecular motion in polymer crystals
Authors: Okano Koji 
Published: June 2010

AbstractA theory of the relaxation phenomena associated with the molecular motion in polymer crystals (the so‐called crystalline relaxation) developed by the author is outlined. These relaxation phenomena are considered to arise from the viscous interaction between polymer chains in crystals due to the incoherent lattice vibrations. Based upon the equilibrium theory of the stability of polymer crystals developed by Peterlin et al., a semi‐quantitative theory of crystalline relaxation is given. The main conclusion reached is that the relaxation strength and the relaxation times depend strongly upon the thickness of platelike single crystals or lamellae. The experimental facts known so far agree, al least qualitatively, with the theory.
Relaxations in crystalline, paracrystalline, and glassy phases in polymers
Authors: Wada Yasaku , Tsuge Kenji , Arisawa Kunio , Ohzawa Yoshiyuki , Shida Ken‐Ichi , Hotta Yasuko , Hayakawa Reinosuke , Nishi Toshio 
Published: June 2010

AbstractMechanical and dielectric relaxations in crystalline phase (crystalline relaxation), glassy phase (local mode relaxation), and paracrystalline phase (paracrystalline relaxation) are interpreted in terms of torsional motion of chains in respective phases. A theory is developed on the relaxation strength, and a satisfactory agreement is found between theory and experiment for mechanical crystalline relaxations in normal paraffins. Dielectric crystalline relaxations in oxidized paraffins, poly(vinyl alcohol), and polyoxymethylene, dielectric paracrystalline relaxation in polyacrylonitrile, and local mode relaxations in several polymers are studied both experimentally and theoretically.
Deformation mechanism of polyethylene spherulite at elevated temperatures near crystal‐disordering temperature
Authors: Oda Takashi , Sakaguchi Nobuhiro , Kawai Hiromichi 
Published: June 2010

AbstractThe effects of temperature upon the orientation behavior of polyethylene crystallites during stretching of the bulk polymer have been measured by means of the x‐ray diffraction technique and interpreted in terms of the deformation mechanism of polyethylene spherulites. With increase of the stretching temperature, especially beyond the crystal‐disordering temperature, the crystal rotation around the crystal a axis probably due to the shearing deformation of crystal lamella along the (001) plane is promoted while the crystal rotation around the crystal b axis due to the untwisting of crystal lamella, is depressed, and the spherulite deformation may be represented by such a fashion as decreasing the number of shells in Wilchinsky's multiple concentric shell structure.
Dynamic viscoelastic properties of dilute polymer solutions
Authors: Tanaka Hidejiro , Sakanishi Akio , Kaneko Motozo , Furuichi Jiro 
Published: June 2010

AbstractThe intrinsic rigidities and the dynamic intrinsic viscosities have been determined from the high‐frequency measurements of viscoelastic properties of dilute solutions in which polymer molecules possess different conformations. Corresponding to them, the limiting relaxation times have been obtained from the steady‐flow viscosity measurements of the same solutions. Data are quantitatively compared with the molecular theories of viscoelasticities of dilute polymer solutions through normalized dispersion curves. Results for polyisobutylene in benzene at theta temperature agree with the Zimm theory (nondraining case) and in cyclohexane (good solvent) are intermediate between the House and the Zimm theory (partially freedraining). It appears that draining effects have some correlation with excluded volume effects. Concentration dependence of complex rigidities also shows correlation with chain expansion, and this phenomenon is due to interchain interaction. Results for poly‐γ‐methyl‐D‐glutamate and poly‐γ‐benzyl‐I‐glutamate in helix solvents show qualitative agreement with the Kirkwood‐Auer theory for rodlike polymers. Preliminary observations for D,L‐copoly‐γ‐bennyl glutamate in dioxane indicate some difference from the above results.
Plastic deformation of polyethylene. Mechanism and properties
Authors: Peterlin A. 
Published: June 2010

AbstractStudies of single‐crystal deformation explain the small‐ and wide‐angle x‐ray observations of the cold drawing of PE, particularly the effects in the necking zone where the original spherulitic structure is transformed into a highly aligned fiber structure. Whole blocks of folded chains are broken out of the original crystals, which have undergone a substantial deformation by phase transformation, twinning, chain tilting, and slip, and are incorporated in the new fiber structure. The latter contains a great many highly strained tie molecules with an entropy and heat content lower than in a completely relaxed supercooled liquid. Melting experiments yield the heat content reduction which is a consequence of more extended chain conformation (intramolecular energy) and of closer chain packing (intermolecular energy). The entropy and enthalpy reduction explains the drastic decrease of sorption and diffusion of solvents first observed in wide‐line NMR experiments. Annealing at sufficiently high temperature (118°C.) lets the sample relax nearly instantaneously. The long period, heat content, diffusion, and sorption assume values corresponding to the temperature of annealing. If the plastic deformation is performed at so high a temperature that annealing effects are not more negligible (hot drawing), the drawn sample still consists of highly oriented crystals but the molecules in the amorphous regions are rather relaxed so that their density, entropy, and heat content do not appreciably differ from the values of a supercooled liquid.
Crystallization Kinetics of Polycarbonates in Solutions
Authors: Luňák S. , Bohdanecký M. 
Published: June 2010

AbstractThe crystallization kinetics in solutions of polycarbonates were studied in three mixed solvents at the critical solvent‐nonsolvent ratio. The dependence of the crystallization rate on the polymer concentration and molecular weight, on the temperature, and the chemical character of the solvent‐nonsolvent mixture was established. Some consequences were deduced for the precipitation fractionation.
Catalysis of the Propagation Reaction in Ziegler‐Natta Polymerization
Authors: Veselý K. , Ambrož J. , Mejzlík J. , Spousta E. 
Published: June 2010

AbstractThe results on the catalytic action of counterions of homogeneous ionic polymerizations are reviewed. By analogy, positively charged counterious play an important role in the heterogeneous system TiCl3–AlR3. This is illustrated by the influence of “defects” in the TiCl3 on the course of a given reaction. Counterions of different structures act in the polymerization as centers of different stereospecificity.
Zur Temperaturabhängigkeit der elektrischen Durchschlagfestigkeit amorpher Polymeren mil Relaxation unter der Glastemperatur
Authors: Artbauer J. 
Published: June 2010

AbstractAnalysis of the conditions for electric breakdown in amorphous polymers indicates that the reduction of electric strength with increasing temperature is due to molecular relaxation processes and change of the free volume. To verify this conclusion in the case of polymers with relaxation below the glass temperature Tg, the breakdown strength of a weakly plasticized polyvinyl chloride was measured in the neighborhood of Tg. The electric strength diminishes below Tg already; at Tg it begins to fall more rapidly. A change of Tg attained by altering the degree of plastification resulted in a corresponding shift of the point, where the breakdown strength–temperature curve begins to fall more steeply. These results agree essentially with the conclusions of the theoretical reasonings, in which the relaxation processes and free volume play a decisive part.
Diffusion of Polyisobutylene in Very Dilute Solutions
Authors: Porsch B. , Kubín M. 
Published: June 2010

AbstractThe diffusion of polyisobutylene in very dilute solutions was investigated. With the interferometric method used the maximum error in D was 2%. Diffusion coefficients of the fractions were measured as a function of molecular weight and concentration down to 0.02 g./dl. The hydrodynamical parameters of the coil were determined. A comparison of molecular weights of fractions measured by light scattering and computed from intrinsic viscosity and D was given. It was possible to characterize the polydispersity of polymers on the basis of diffusion measurements.
Micromethod for Estimation of the Degree of Crosslinking in Elastomers from Compression Modulus of Swollen Vulcanizates
Authors: Smith Derek A. 
Published: June 2010

AbstractThe method uses small specimens (of volume less than 0.1 cc.) which swell to diffusion equilibrium in hydrocarbon solvents within 8 hr. Measurements of deflection to better than 1 μ are made with a modified Wallace microhardness tester, which is described. The name “reticulometer” is proposed for this instrument. Using peroxide‐crosslinked natural rubbers swollen to equilibrium vr values of about 0.23 in n‐decane or in benzene, values for the concentration of physically active network chains determined by the present method were not greatly different from those determined by conventional “equilibrium” streus‐strain measurements in tension on the same samples. Detailed differences are discussed. The chief advantages of the microcompression method are: (a) the use of small samples of shape and size convenient for carrying out other conventional measurements of network chain density; (b) the rapid attainment of diffusion equilibrium encouraging the use of fully swollen specimens and minimizing the risk of inhomogeneous distribution of swelling agent; and (c) the rapidity of testing compared with tension measurements.
The thermodynamic properties of solutions of polystyrene and of low molecular weight model compounds
Authors: Pouchlý J. , Biroš J. , Šlc K. , Vondrejsová J. 
Published: June 2010

AbstractBinary mixtures of polystyrene, two low molecular weight model compounds, ethyl‐benzene and 1,3‐diphenylbutane, and benzene have been studied. The mixing parameters of these systems have been determined by calorimetry, pyenometry, and osmometry, and by measurement of vapor pressures and degrees of swelling. The results correspond qualitatively to predictions from the cell theory and from theories based on the theorem of corresponding states. The enthalpy, entropy, and volume of mixing are more negative in the homologous series for a greater difference in the molecular sizes of the components; the free enthalpy of mixing, however, becomes less negative and thus the x parameter increases. Several equations, useful in evaluating the mixing parameters according to the new Flory et al.11,12 theory have been derived. The values of the interaction parameter x12 have been calculated by means of these, and it has been found that the theory represents the measured data semiquantitatively.
Crystal structures of some isotactic hydrocarbon polymers
Authors: Noether H. D. 
Published: June 2010

AbstractUnit cell dimensions for several new isotactic polyhydrocarbons have been determined: Poly(vinyl cyclohexane)II, tetragonal, a = 20.48 A., c = 44.58 A., 247 helix; poly(vinyl cyclopentane); I: tetragonal, a = 20.14 A., c = 6.50 A., 41 helix; II: tetragonal, a = 20.11 A., c = 19.5 A., 123 helix; III: tetragonal, a = 37.3 A., c = 19.8 A., 103 helix; poly(vinyl cycloheptane): tetragonal, a = 23.4–23.5 A., c = 6.5 A., 41 helix; poly(vinyl cyclobutane): tetragonal, a = 34.1 A., c = 6.6 A., 41 helix; poly(3‐methyl butene), tetragonal, a = 34.3 A., c = 6.85 A., 41 helix, poly(allyl cyclopentane): tetragonal, a = 20.34 A., c = 47.49 A., 247 helix; poly(allyl cyclohexane): I: tetragonal a = 21.06 A., c = 20.09 A., 103 helix; II: hexagonal, a = 19.12 A., c = 6.33 A., 31 helix; poly(metamethyl styrene): tetragonal, a = 19.9 A., c = 78.9 A., 4011 helix; poly(4,4‐dimethyl pentene): tetragonal, a = 20.3 A., c = 13.8 A., 72 helix. Analysis of above unit cell data and those of the published literature seems to indicate that only 31 type helices can be accommodated in the hexagonal system, while the other isotactic structures between 3 and 4 monomers per turn crystallize in the tetragonal or orthorhombic systems. The various possibilities of expanding the central helix by varying the diameter and the pitch in order to satisfy the space requirement of the substituting side groups are discussed.
On some kinetic aspects of solid‐state polymerization
Authors: Papissov I. M. , Kabanov V. A. , Papissov I. M. , Kabanov V. A. 
Published: June 2010

AbstractSolid‐state polymerization is considered as an irreversible phase transition of monomer erystals into polymer. The theoretical relationship between critical size of the polymer nucleus in a monomer crystal and single macromolecule dimensions is obtained on the assumption that the polymer nucleus formed by closely packed extended macromolecules has a cylindrical shape. By using this relationship it is shown that in some cases the growing of a single chain in a monomer crystal could be thermodynamically unfavorable. In such cases one should expect the propagation of bundles of macromolecules. Processes of this kind are characterized by a slow nucleation rate and autocatalytic acceleration at the polymer‐monomer interphase. At the same time it is supposed that in the course of irradiation of single macromolecules could instantly grow in some “hot” regions of a monomer crystal. If the “critical” nucleus has to contain more than one macromolecule, the “cooling off” of these regions should be followed with quenching of thermodynamically unstable single polymer chains, which then could be depolymerized under irradiation or annealed. This consideration is used to explain some cases of low limit conversions into polymer observed for a number of crystalline monomers.
Orientation and deformation of polystyrene molecules in a hydrodynamic field
Authors: Munk P. , Poupětová D. , Bohdanecký M. , Dillingerová M. 
Published: June 2010

AbstractFlow birefringence and gradient viscometry methods have been used to measure several fractions of high molecular weight polystyrene in several solvents of different viscosity, but with virtually the same refractive index as polystyrene. The stress‐optical law, Zimm's and Peterlin's theories of orientation and deformation of the macro‐molecular coil, and Peterlin's theory of the influence of concentration on the hydrodynamic behavior of a polymer have been verified. The results of these tests are discussed from the viewpoint of anisotropy, of the intramolecular as well as intermolecular hydrodynamic interaction.
Modification of poly(vinyl alcohol) by heat in the presence of chromium compounds
Authors: Duncalf B. , Dunn A. S. 
Published: June 2010

AbstractFilms of poly(vinyl alcohol) containing 20 mole‐% residual acetate groups are readily soluble in cold water. Films heated to temperatures above 170°C. crystallize and become insoluble in water although they are swollen by it. Heating to temperatures above 240°C. produces films which are no longer swollen by water. Thermogravimetry shows that there is no extensive decomposition below 270°C., but differential thermal analysis reveals a strongly exothermic reaction in this temperature range. It is believed that a crosslinking reaction occurs in the 240‐270°C. range.
Polymerization of certain vinyl monomers in liquid crystals
Authors: Amerik Y. B. , Krentsel B. A. 
Published: June 2010

AbstractWhile studying the phase transition of vinyl oleate, it was proven that vinyl oleate possesses the liquid crystal state. The radiation‐induced polymerization of vinyl oleate was carried out in liquid, liquid crystalline, and solid states. The presence of double bonds in substitution causes very slow polymerization of vinyl oleate in comparison with other vinyl ester of saturated fatty acids. The structure of forming polymer greatly depends on the phase state of the monomer in the process of polymerization. In liquidphase polymerization, the transparent polymer was generated and it was an isotropic, viscous liquid. If the polymerization was done in liquid crystal or crystal state, the crystalline polymer was obtained. The melting point of this polymer t = 34‐38°C. The considerable mobility of chains in poly(vinyl oleate) crystal, the inability to keep its form, and data from x‐ray patterns permitted us to consider its state as a liquid crystalline one.
Penetration and replacement of polyvinylpyridine layers adsorbed on a mercury surface by fatty alcohols
Authors: Miller Israel R. 
Published: June 2010

AbstractInformation on the structure of the adsorbed layer of polyvinylpyridine (PVP) was obtained by letting it compete for the surface sites with fatty alcohols, e.g., hexanol, amyl alcohol, octanol. The surface occupancy by either vinylpyridine residues or by the alcohols was obtained from differential capacity measurements. Below a threshold concentration of the fatty alcohol, which is a function of its standard free energy of adsorption, it does not displace the vinylpyridine from the surface at any potential. It penetrates, however, the loopholes left on the mercury surface by the adsorbed polyelectrolyte coil and provides a means for a determination of the loophole area. At higher concentrations the fatty alcohols start replacing the vinylpyridine residues in the surface over potential spans, which increase with alcohol concentration. The replacement process does not depend on polymer concentration but merely on the internal concentration of the residues in a polymer molecule near the surface. For evaluation of the concentration of the residues in the polymer similar competition experiments between fatty alcohols and ethylpyridine which is the monomeric analogon of PVP were carried out.
Inorganic polymers. Part III. The polymerization of P‐phenyl‐N,N′‐disubstituted phosphonic diamides
Authors: Shaw R. A. , Ogawa Takeshi 
Published: June 2010

AbstractThe thermal bulk condensation polymerization of a series of P‐phenyl‐N,N'‐disubstituted phosphonic diamides, PhP(O)(NHR)2, (R = Me, Et, Prn, Pri, Bua, Bui, Bus, But, eyclohexyl, or Ph) has been investigated. The relationships among the number average degree of polymerization, the substituents R, and the polymerixation times have been studied. For two of these diamides (R = Ph or eyclohexyl) only dimers were obtained. For the others, polymeric materials of number‐average molecular weights in the range 500‐1300 could be obtained. Attempts to use the cyclic dimer [PhP(O)NPh]2 as starting material for ring‐opening polymerizations were unsuccessful. The mechanisms of the polymerization reactions are discussed.
The effect of temperature on the cationic isomerization polymerization of 3‐methyl‐1‐butene and 3‐chloro‐3‐methyl‐l‐butene
Authors: Kennedy J. P. , Squires R. G. 
Published: June 2010

AbstractThe effect of temperature on the molecular weight and product structure of poly(3‐methyl‐1‐butene) and poly(3‐chloro‐3‐methyl‐l‐butene) obtained with A1C13 catalyst in ethyl chloride solvent in the temperature range from +10 to −130°C. has been investigated. The plot of the logarithm of molecular weights versus reciprocal temperature for poly(3‐methyl‐l‐butene) is linear between +10 and −80°C. (ΔEDP = −2.5 kcal./ mole). At about −80°C. there is a change in the mechanism and the curve assumes a lesser slope in the range from −100 to −130°C. (ΔEDP = −0.35 kcal./mole). The structure ratio P1.3p1.2 of the polymer, i.e., the ratio of the number of 1,3 enchainments in the polymer to the number of 1,2 units, is also a linear function of the reciprocal temperature in the range from +10 to about −100°C. At −100°C. there is a break in the linearity and the slope increases sharply indicating the formation of large amounts of 1,3 units. The structure ratio of poly(3‐chloro‐3‐methyl‐l‐butene) is also linear but it is only little affected by the temperature in the −30 to −130°C. range. A possible explanation for these findings is offered and differences between chlorine‐containing and hydrocarbon carbonium ions are discussed.