bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid‐state polymerization of styrene oxide and propylene oxide by high‐energy radiation
Authors: Tabata Yoneho , Sobue Hiroshi 
Published: June 2010

AbstractRadiation‐induced polymerizations of styrene oxide and propylene oxide were carried out by using electrons from a Van de Graaff generator in the liquid and solid states of the monomers. It was found from the experiments that styrene oxide is polymerizable in both liquid and solid states; on the other hand, propylene oxide can be polymerized in the solid state only in the presence of styrene oxide. It was suggested that the chain transfer and isomerization reactions are rapid and play an important role in the polymerization of styrene oxide. Because polymerization of propylene oxide in bulk in the liquid and solid states is not possible, it may be suggested that the polymerization proceeds in an amorphous monomer phase or in a crystalline phase which is modified by the addition of styrene oxide.
Effect of pressure on radiation‐induced solid‐state polymerization of methacrylonitrile
Authors: Suzuki Toshihiko , Tabata Yoneho , Oshima Keichi 
Published: June 2010

AbstractThe effect of pressure up to 5000 atm. on the solid‐state polymerization of methacrylonitrile at low temperature was investigated. It was found that the rate of polymerization is always suppressed by pressure in the solid state at low temperatures, −43, −78, and −196°C. In polymerization at −78°C. the number of polymers is less at 5000 atm. than at 1 atm. while the molecular weight is clearly larger at 5000 atm. than at 1 atm. On the other hand, there is not such a large difference in the number of polymers between 1 and 5000 atm. at −43°C. In contrast with the polymerization at −78°C., the molecular weight is obviously higher at 1 atm. than at 5000 atm. It may be suggested that the pressure effect on the solid‐state polymerization of methacryloni‐trile is not due to the change of the entropy of activation by pressure, but by the change of the enthalpy of activation, except for polymerization at −43°C. under 1 atm.
Adsorption of polystyrene, poly(dimethyl siloxane), and poly(methyl methacrylate) from dilute solution
Authors: Eltekov Yu. A. 
Published: June 2010

AbstractThe polymer adsorption depends upon the character of pore structure and the nature of the adsorbent surface. The comparison of the polystyrene adsorption from the CCl4 solution on macroporous adsorbents with different pore diameters permits one to evaluate the size and shape of polymer macromolecule. A dense monolayer of adsorbed polystyrene macromolecules on the surface of rutile, graphitized carbon black, and aerosil is formed. The poly(dimethyl siloxane) macromolecules are displaced by hexane molecules from the surface of graphitized carbon black.
Some aspects of vapor‐induced crystallization of polycarbonate of bisphenol A
Authors: Mercier J. P. , Groeninckx G. , Lesne M. 
Published: June 2010

AbstractA method is presented to crystallize polycarbonate of bisphenol A under constant vapor pressure of solvents at near ambient temperatures. Methylene chloride and acetone were used as crystallizing liquids. Acetone is more powerful in inducing crystallization but the final degree of crystallinity does not depend on the nature of the solvent. The crystalline degree is low as found in the literature for this polymer. This method is very useful to crystallize materials reluctant to thermally induced crystallization such as polycarbonate.
Macromolecular products of the reaction of ethylenimine with imides
Authors: Grundschober F. , Sambeth J. 
Published: June 2010

AbstractThe reaction of ethylenimine with unsubstituted and substituted imides of carboxylic acids has been investigated. The formation of macromolecular substances occurring by the opening of the rings of the reaction partners was observed. Depending on the conditions of reaction, either linear or crosslinked products containing amide, or amide and amine linkages, respectively, were obtained. When unsubstituted or substituted maleimides were used, monomeric aziridinylsuccinimides with great reactivity were obtained and were easily transformed into insoluble and infusible crosslinked resins. The mechanisms of the various polyaddition reactions are discussed, and the properties of the macromolecular products obtained are reported.
Stereoregularity of poly(methacrylic acid esters)
Authors: Matsuzaki K. , Ishida A. , Tateno N. , Matsuzaki Kei , Ishida Akira , Tateno Noriaki 
Published: June 2010

Abstractl‐Menthyl methacrylate (l‐MnMA) and dl‐MnMA and their mixtures were poly merized with benzoyl peroxide (BPO), phenylmagnesium bromide (PhMgBr), and lithium aluminum hydride (LiAlH4), as catalyst. The isotacticity of the polymers of dl‐MnMA polymerized with PhMgBr was independent of the polymerization temperature and low. The tacticity of the polymers from the mixtures of l‐ and dl‐MnMA's polymerized with BPO hardly changed with monomer compositions, while that with LiAlH4 showed increase with the increase of l‐monomer contents. Thechange of the optical activity of PMnMA's with the stereoregularity is slight as compared with large variation of the tacticity of the polymers. Although both in radical and anionic polymerizations preference of one monomer to another monomer does not occur, in isotactic polymerization with LiAlH4 asymmetric induction of menthyl groups on the main chain configurations takes place. The tacticities of some poly(methacrylic acid esters) polymerized with PhMgBr under similar conditions were compared.
Degradation of polyphosphates in solution. III. Hydrolysis of linear long‐chain sodium polyphosphate
Authors: Strauss Ulrich P. , Krol George J. 
Published: June 2010

AbstractThree samples of sodium polyphosphate (DP ≈ 30, 75, and 170) were degraded at pH 5 and 65.5°C., and specific rate constants for individual processes were determined. The first‐order rate constant for the formation of orthophosphate from endgroups was independent of chain length and about 50 times as large as the rate constant for the chain scission per interior phosphate group. The latter rate appeared to increase with increasing DP. The formation of trimetaphosphate was more than 10 times as fast at a given chain end than at a given middle group. Assuming that the reaction at the chain ends was independent of DP, the specific rate for the formation of trimetaphosphate from middle groups increased with DP also.
Infrared spectrum and structure of poly[3,3‐bis(chloromethyl)oxacyclobutane]
Authors: Enomoto S. , Opaskar C. G. , Krimm S. 
Published: June 2010

AbstractPoly[3,3‐bis(chloromethyl)oxacyclobutane] is known to occur in two crystal forms, α and β, which exhibit the same fiber axis identity period but different unit cell cross‐sections. To test if these differences might be due to differences in conformation of the —CH2Cl side chains, normal coordinate calculations were carried out for the three possible isomeric structures: trans‐trans, trans‐gauche, and gauche‐gauche. It was found that the bands in the infrared spectrum could be assigned to frequencies of these three isomers. Furthermore, this correlation suggests that the α form is associated with the gauche‐gauche isomer, while the β form is associated with the trans‐trans isomer. The proportion of trans‐gauche isomer increases when the polymer is melted.
The role of free ions in reactions of olefins with soluble complex catalysts
Authors: Dyachkovskii F. S. , Shilova A. K. , Shilov A. E. 
Published: June 2010

AbstractIt was found that in the homogeneous catalytic system (C5H5)2TiCl2 + Al(CH3)2Cl the catalytic activity is due to the presence of free ions, presumably (C5H5)TiCH3 formed in the equilibrium: (C5H5)2TiCH3Cl. AlCH3Cl2 ⇄ (C5H5)2Ti+CH3 + Al(CH3) Cl3 ‐ Further evidence for the suggested mechanism has been found. By means of electrodialysis the formation of positive ions containing Ti was shown. Catalytic activity appears only in the presense of the latter. The increased cataivtiy activity in comparatively polar solvents (CH2Cl2, C2H4Cl2) is connected with the increased number of the ions. The linear dependence of log k (k is the rate constant of the reaction of free ion with an olefin) with 1/D (D is the dielectric constant) was found in five different solvents and their mixtures.
Dynamic‐mechanical analysis of olefin polymers
Authors: Tuijnman C. A. F. 
Published: June 2010

AbstractThe shape of the dynamic moduli vs. temperature curves of polymers fundamentally depends on the temperature dependence of the relaxational properties of the polymers. When the frequency dependence of the reduced loss modulus is represented by an empirical function describing the dispersion peak, the distribution of the relaxation times and the storage modulus vs. frequency curve corresponding to that peak can be calculated. The temperature dependence of the reduced moduli can then be expressed as a function of the activation energy of the relaxation process and of a single parameter describing the width of the relaxational distribution function. This analysis is useful for a better understanding of the loss modulus vs. temperature spectrum and is applied to a linear polyethylene. Furthermore, a discussion is given of the differences in the spectra of linear polyethylenes and polypropylenes, mixtures of polyethylene and polypropylene, and copolymers of ethylene and propylene. When ethylene is randomly built into a polypropylene chain, the β‐transition of polypropylene is shifted to lower temperatures over a distance which is determined by the ethylene content. No shift is observed in mixtures of polyethylene and polypropylene. Here, the β‐peak of the loss modulus vs. temperature spectrum is only lowered and its height is a measure of the amount of amorphous polypropylene. The height of the loss modulus in the α‐region is determined by the total fraction of crystalline material in the mixture, the height of the γ‐peak is proportional to the ethylene content. The loss modulus spectrum can, to a large extent, be used for distinguishing between these different polymers.
On the theory of thermal diffusion in dilute polymer solutions
Authors: Khazanovich T. N. 
Published: June 2010

AbstractThe thermal diffusion coefficient in highly diluted polymer solutions is calculated. The pearl necklace model is used for description of flexible macromolecule dynamics. It is assumed that the usual diffusion equation holds under non‐uniform temperature conditions, but the coefficients of equation are variables. Free‐draining flexible macromolecules are considered. The thermal diffusion coefficient is found to be proportional to the bead diffusion constant and therefore is controlled by the kinetic flexibility of chain. In accordance with experiment the thermal diffusion coefficient does not depend on molecular weight and concentration. With eq. (9) it is possible to calculate from experimental data the bead diffusion constant and therefore to obtain the kinetic rigidity of the polymer.
Theories of electronic behavior in macromolecular solids
Authors: Pohl Herbert A. 
Published: June 2010

AbstractMany examples of electronically conducting aperiodic polymeric solids now exist. These supply enough inherent electronic carriers to be classed as semiconductors at laboratory temperatures. Such enhanced electronic conduction arises only in the presence of either (or both) donor‐acceptor action (usually intermolecular), or ekaconjugation (intramolecular). Quantum mechanical and experimental evidence shows that conjugation can be of two types; exhalted or “ekaconjugation” and self‐limited or “rubiconjugation.” These play a strong role in organic conduction. The energetics of carrier origins, the mobilities of carriers, and the effects of morphology and impurity are critically discussed, as well as the relative roles in electrical polarization mechanisms of variously excited electrons such as (a) ground‐state electrons—contributing to normal “electronic” polarizability, (b) Frenkel (or intermolecular) excitons, (c) Mott (or intramolecular) excitons, (d) Von Hippel polarons or “quasi‐bound” electrons, and (e) “free” electrons, i.e., those in the conduction band. Mott excitons and polarons in macromolecular solids can contribute in a new and strong fashion because of the unusual size of the monopoles present in the form of delocalized charges ranging over long molecular regions. This strong type of polarizability, recently observed, is called hyperelectronic polarization.
Band conduction and fluctuations in polymeric semiconductors
Authors: Burgess R. E. 
Published: June 2010

AbstractThe conditions for band conduction to occur in a semiconductor are reviewed in terms of order, bandwidth, effective mass, and momentum relaxation time. The nature of available experimental data and their validity and interpretation are discussed. In particular, the use of polycrystalline material, the effects of injection and trapping and uncertainties in the effective masses of the carriers, and the temperature dependence of the activation energy are considered. The commonly made but arbitrary assumption of intrinsic semiconduction is examined and the implications of the alternative hypothesis of extrinsic conduction are discussed. Detailed attention is devoted to the interpretation of the experimentally accessible parameters: conductivity, Seebeck coefficient, drift mobility, Hall coefficient, magnetoresistance, Dember effect, and possible reasons for incompatibility among these data are suggested. Breakdown mechanisms in high fields are briefly reviewed. The fluctuations of current or voltage in a polymeric semiconductor are discussed theoretically and the implications of the measurements of noise under various conditions are outlined. They may be used to (a) determine marked departure from thermal, elastic, and electrical equilibrium, (b) determine the relaxation times of electron transitions contributing to the conduction mechanism, and (c) indicate the mechanism and response time of the breakdown process in high fields.
The transmission of light by films of crystalline polymers
Authors: Clough S. , Rhodes M. B. , Stein R. S. 
Published: June 2010

AbstractThe transmission of polarized light by films of crystalline polymers depends on the size, shape, orientation, anisotropy, and arrangement of the constituent crystallites. Its measurement as a function of the polarization direction of the incident light and that of the analyzing polarization filter characterizes the structure. This may be readily followed during the crystallization or deformation of the polymer. The transmission depends upon some of the same optical parameters as does the scattering and provides complementary information. The scattering, measured as a function of angle, is capable of providing more information than the transmission but its measurement during rapid processes is more difficult. The utility of these techniques is illustrated for the isothermal crystallization of oriented polyethylene films and for the stress‐induced crystallization of rubber.
Poly(phenylene)triazoles: New thermally stable fibers
Authors: Lilyquist M. R. , Holsten J. R. 
Published: June 2010

AbstractA chemical cyclocondensation reaction process has been developed to convert the easily prepared poly(phenylene)hydrazide to the corresponding high molecular weight poly‐3,5‐(m‐, p‐phenylene)‐4‐phenyl‐1,2,4‐triazole. Polytriazole fibers have been spun from formic acid solutions utilizing both wet and dry spinning techniques. These fibers develop a high degree of orientation and crystallinity on stretching at temperatures of 300°C. and higher. Such fibers retain approximately 30% of their initial breaking strength at a temperature of 300°C. and are not seriously degraded on exposure to elevated temperatures for prolonged periods. The fiber dimensional stability at temperatures above the glass transition temperature of 260°C. for the amorphous polymer was found to be directly related to the fiber orientation and crystallinity. The ease of fabrication and thermal stability of the phenylene triazole polymer makes this material potentially attractive for other end‐use applications such as films, protective coatings, and electrical insulation.
Aromatic Poly‐1,3,4‐Thiadiazole Fibers
Authors: Frazer A. H. , Fitzgerald W. P. 
Published: June 2010

AbstractIt has been shown that aromatic poly‐1,3,4‐thiadiazole fibers can be prepared in a manner analogous to that of the aromatic poly‐1,3,4‐oxadiazole via the thermal cyclode‐hydration of an aromatic polyoxathiahydrazide fiber. These fibers exhibited the same high level of thermal and hydrolytic stability observed for the aromatic poly‐1,3,4‐oxadiazole fibers. The oxathiahydrazide‐thiadiazole conversion was found to occur at lower temperatures and much faster rates than the hydrazide‐oxadiazole conversion.
Boron nitride fibers
Authors: Economy J. , Anderson R. V. 
Published: June 2010

AbstractThe structure and properties of boron nitride fibers were examined. The fibers are polycrystalline consisting of a major phase of turbostratic boron nitride and a three‐dimensional ordered phase which is not hexagonal. The density of the fibers is determined by the amount of internal microporosity and crystal interlayer spacing. The existence of internal defects and necking‐down defects is described. The resistance of the fibers to refluxing water is shown to be closely related to the interlayer spacing. This effect of the crystal structure on the high thermal stability of the fibers is discussed. The mechanical properties are interpreted in terms of the microcrystalline structure. The electrical resistivity of BN fibers is compared to other insulators and arguments are presented to explain the difference between the conductivity of graphite and boron nitride.
A molecular theory of polymer chain folding
Authors: Lindenmeyer P. H. 
Published: June 2010

AbstractA molecular theory is proposed to account for the regular folding of polymer chains during crystallization. It predicts that an isolated polymer chain greater than some critical length can lower its energy by crystallizing into a regular folded‐chain conformation. Similarly, a single molecular chain crystallizing upon an infinitely large substrate will also lower its free energy by regular folding. In a crystal composed of polymer molecules all having the same length the lowest free energy occurs when all chains are completely extended; however, there also exists a whole series of metastable states corresponding to one, two, three, etc. folds per molecules. When the crystal is composed of a distribution of molecular lengths, the lowest free energy corresponds to a folded‐chain crystal whose thickness is a sensitive function of the distribution. If the low end of the molecular length distribution is assumed to be truncated at the observed length of extended‐chain crystals, the theory satisfactorily predicts the observed thicknesses of folded‐chain crystals obtained by melt crystallization of both fractions and whole polymer.I never saw a folded chain.I never hope to see oneBut I can tell you anyhow.I'm damn near sure there be one.
The efficiency of gel permeation chromatography
Authors: Meyerhoff G. 
Published: June 2010

AbstractThe resolution power of gel permeation chromatography (GPC) columns and their combinations is tested as a function of the pore sizes of the gels and as a function of the elution velocity. The efficiency of GPC is characterized by the ratio UG/UT, where UG is the experimental, and UT the theoretical, inhomogeneity. The latter quantity is obtained from absolute measurements of Mw, and Mn. The ratio passes through a minimum for a series of columns with increasing pore sizes. The minimum occurs at that column or column set which is best suited to resolving a given polymer. UG/UT for any column decreases with decreasing elution velocity. At a certain velocity UG/UT becomes 1. This velocity is usually smaller than v = 1 ml./min., but for some columns appreciably greater. Columns with low UG/UT values allow an unexpectedly good separation of mixtures of two polymers with Mw/Mn = 2 and Mw(I)/Mw(II) = 2. A compression effect toward the peaks of the two components is observed.
Measurement of functional group and molecular weight interrelations by GPC/IR
Authors: Terry Stuart L. , Rodriguez Ferdinand 
Published: June 2010

AbstractWhen the effluent from a gel permeation chromatograph is analyzed by infrared absorbance on a continuous basis (GPC/IR), individual functional groups can be followed. Successive analyses at different characteristic wavelengths permit the estimation of group distribution within a molecular weight distribution. The use of low molecular weight internal standards that combine the functional groups of interest is shown to enhance the reliability of the method. A mixture of polymers of styrene and methyl methacrylate and a copolymer of the two have been analyzed with phenyl benzoate as an internal standard. It is demonstrated also that the relative concentration of hydroxyl and ether groups can be monitored in a mixture of poly(ethylene oxide) homologs. Among the polymer substituent groups successfully analyzed in GPC/IR with trichloroethylene as solvent are OH, COC, SiOSi, CF, CH2, carboxyl, and phenyl.
Simultaneous measurement of oil content and molecular weight distribution of oil‐extended elastomers by gel permeation chromatography
Authors: Mate R. D. , Lundstrom H. S. 
Published: June 2010

AbstractThis paper describes the successful application of gel permeation chromatography to the measurement of both molecular weight distribution and oil content in oil‐extended elastomers with a single analysis. In this investigation, different solvents and column sequences were employed to study several typical aromatic, naphthenic, and paraffinic oils. Two out of the three oils studied were completely separated from both high polymer and solvent impurity regions. Calibration techniques and data obtained therefrom are discussed herein.
Gel permeation chromatography in the analysis of surface coating vehicles
Authors: Bartosiewicz R. L. 
Published: June 2010

AbstractSurface coatings are usually generated in situ from complex systems often containing two or more phases. The film‐forming phase, called the vehicle, is in itself complex. There is usually a chemical composition distribution superimposed upon the molecular size distribution. The principal film‐forming component of the vehicle is in turn quite complex: it is usually a resin or blend of resins quite heterogeneous in molecular size, shape, and composition distributions. The determination of an absolute molecular weight for the resins incorporated into vehicles is thus difficult and may be meaningless. However, both vehicles and their film‐forming resin components can be fractionated quite well by gel permeation chromatography. In addition to providing fractions for further analysis by other techniques, the chromatogram obtained simultaneously yields much information concerning the vehicle or vehicle component not easily obtainable by former analysis schemes.
Polymerization of nitrogen‐containing and oxygen‐containing monomers by Ziegler‐Natta catalysts
Authors: Giannini U. , Brückner G. , Pellino E. , Cassata A. 
Published: June 2010

AbstractThe polymerization of oxygen‐ and nitrogen‐containing monomers by Ziegler‐Natta catalysts is described. In particular, the results obtained in the polymerization of unsaturated tertiary amines are reported. The polymerization is possible when both the nitrogen atom of the monomer and the aluminum atom of the organometallic compound used in the catalysis are shielded by branched alkyl groups. The influence of the distance of the nitrogen atom from the double bond is also studied. The polymerization of monomers containing siloxanic or silazanic groups are described. By hydrolysis of the polymers in an acid medium crystalline polymers of primary alcohols and an amorphous polymer of a secondary amine have been isolated.