bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copolymerization of N‐ethylmaleimide with stilbenes
Authors: Yamakita Hiromi , Hayakawa Kiyoshi 
Published: April 2003

AbstractCharge‐transfer complexes in solutions of ethylmaleimide and stilbenes have been characterized by spectroscopy. The stoichiometric compositions of these complexes have been shown by Job's method to be 1:1 molar complexes. The value of the equilibrium constant K for complex formation of ethylmaleimide with stilbene derivative increases in the following probable order: ethylmaleimide–stilbene ≪ ethylmaleimide–dimethylaminostilbene (DMAS) < ethylmaleimide–aminodimethylaminostilbene (ADMAS). From the calculations of the electron density of the highest occupied level for the stilbenes, the charge transfer in ethylmaleimide–DMAS and ethylmaleimide–ADMAS is attributed to n → π transition, while the charge transfer in ethylmaleimide‐stilbene is attributed to n → π transition. Copolymerization was carried out by γ‐irradiation in benzene or THF solutions of the comonomer pairs. The alternating tendency of copolymerization was larger in the ethylmaleimide–DMAS system than in the ethylmaleimide–stilbene system. This can be explained by assuming resonance structures in the transition state of addition reaction of DMAS to the propagating ethylmaleimide unit. In the copolymerization of ethylmaleimide with ADMAS, the effect of the penultimate unit was more important than in that with DMAS.
Preparation and properties of polyamide‐sulfonamides
Authors: Imai Yoshio , Okunoyama Hikaru 
Published: April 2003

AbstractA series of polyamide‐sulfonamides was synthesized by the interfacial polycondensation of m‐ and p‐chlorosulfonylbenzoyl chlorides with aliphatic and aromatic diamines at room temperature. Most of the polymers obtained were high molecular weight, film‐forming materials. They were all amorphous and were soluble in a wide range of acidic and basic solvents. Both aliphatic and wholly aromatic polyamide‐sulfonamides showed initial breakdown in the range of 320–360°C under thermogravimetric analysis in a nitrogen atmosphere.
Synthesis of aryleneisopropylidene polymers
Authors: Fritz A. , Rees R. W. 
Published: April 2003

AbstractLinear, high molecular weight aryleneisopropylidene (AIP) polymers have been synthesized via Friedel‐Crafts alkylation reactions. Monomers such as p‐bis‐2‐chloroiso‐propylbenzene condense readily with arylene compounds of high electron density such as naphthalene and diphenyl ether. Catalytic amounts of tritylhexafluoroarsenate catalysts in combination with aluminum chloride and nitrobenzene direct the synthetic reactions towards a pure AIP structure. Side reactions which give polyindane structures through dimerization of p‐bis(2‐chloroisopropyl)benzene are eliminated when the polymerization temperature is kept below −20°C. The preferred solvents are chlorinated compounds. A wide range of structural modifications and properties can be obtained by varying the monomer combinations. Desirable physical properties of AIP polymers include clarity, rigidity, impact toughness, oxidative stability, and resistance to stress cracking.
Photosensitivity and photochemical reactions of poly(vinyl p‐azidocinnamate)
Authors: Yabe Akira , Tsuda Minoru , Honda Koichi , Tanaka Hideaki 
Published: April 2003

AbstractThe spectral sensitivity of poly(vinyl p‐azidocinnamate)(PVACi) was discussed by comparison with poly(vinyl cinnamate)(PVCi) and poly(vinyl p‐azidobenzoate). The photochemical reaction of PVACi was investigated with respect to the reactivity of two functional groups, namely, azido and cinnamoyl groups. It was found that cinnamoyl groups dimerized like PVCi and azido groups did not add to double bonds appreciably. The quantum yield of photolysis of azido groups was two times that of dimerization of cinnamoyl groups. A marked wavelength dependence of π–π* and n–π* absorption was observed in both the reactions of azido and cinnamoyl groups.
Electrocondensation polymers: Electrochemical condensation of aromatic diacetyl compounds
Authors: Laube Bruce L. , Higgins Jerry 
Published: April 2003

AbstractElectrochemical reduction of 4,4′,‐diacetyldiphenylethane at mercury in 80% ethanol/1M potassium acetate produced the pinacols in high yield by the one‐electron/one proton reduction of the carbonyl groups. Although polarographic analysis indicated essentially complete conversion to pinacol, the low inherent viscosities of 0.03–0.06 of the polypinacols implied the presence primarily of oligomers.
The nature of accessible surfaces in the microstructure of cotton cellulose
Authors: Rowland Stanley P. , Roberts Earl J. 
Published: April 2003

AbstractThe accessible regions in cotton cellulose were tagged by the introduction of diethyl‐aminoethyl (DEAE) substituents at DS = 0.034 without other substantial changes in structure. Evidence from rates of hydrolysis of this DEAE cotton to hydrocelluloses and from the composition and structure of the solubilized and insoluble fractions provides the basis for considerable detail regarding two types of accessible regions in the cotton fiber; these are identified as accessible surfaces of elementary fibrils. One type of accessible surface is characterized by molecular chain segments which are distorted and disordered by tilt/twist strain that is concentrated in this segment of the elementary fibril; the second type of accessible surface is characterized by a relatively high degree of order which reflects the high level of crystallinity within the interior of this unstrained segment of the elementary fibril. Substantial differences between these accessible surfaces are discussed. It is estimated that chain segments on accessible surfaces of the first type are substantially disordered, i.e., approximately 60–90% of the D‐glucopyranosyl units are dislocated from positions of perfect crystalline order. Accessible surfaces of the second type are quite highly ordered, i.e., only 5–30% of the D‐glucopyranosyl units dislocated.
Effect of pressure on the radiation‐induced polymerization of ethylene in tert‐butyl alcohol
Authors: Wada Takeshi , Watanabe Terutaka , Takehisa Masaaki 
Published: April 2003

AbstractThe effects of pressure of the radiation‐induced polymerization of ethylene in tert‐butyl alcohol were studied. The reaction was carried out by use of a reactor with a capacity of 100 ml under the following conditions; pressure, 60–400 kg/cm2; temperature, 24 ± 3°C; dose rate, 2.0 × 104−1.6 × 105 rad/hr; amount of medium (tert‐butyl alcohol containing 5 vol‐% water), 70 ml. The results of polymerization were analyzed by a kinetical treatment based on a reaction mechanism with both first‐ and second‐order terminations for the concentration of propagating, radical. On the basis of the kinetical treatment the rate constants of each elementary reaction at several pressures were determined, and the activation volumes of elementary reactions were obtained and are discussed in connection with the reaction mechanism. Consequently, the rate constants of propagation, first‐order termination, and second‐order termination at pressure p and at 24°C were expressed by,
Synthesis of new ordered aromatic polyester copolymers
Authors: Stevenson D. R. , Mulvaney J. E. 
Published: April 2003

AbstractAromatic polyesters of 3,5‐di‐tert‐butyl‐4‐hydroxybenzoic acid and 3,5‐diisopropyl‐4‐hydroxybenzoic acid were prepared. The polymers were found to be high‐melting but largely insoluble in organic solvents. The polymer based on 3,5‐di‐tert‐butyl‐4‐hydroxy‐benzoic acid was not degraded to monomer by sulfuric acid. A number of new aromatic polyesters were also prepared. Several new monomers for aromatic polyesters were synthesized, including bis(2,5‐di‐tert‐butyl‐4‐carbophenoxyphenyl)terephthalate, m‐ and p‐phenylene bis(3,5‐di‐tert‐butyl‐4‐hydroxybenzoate), bis(2,6‐di‐tert‐butyl‐4‐chlorocarboxyphenyl)terephthalate, and m‐phenylene bis(3,5‐diisopropyl‐4‐hydroxybenzoate). An aromatic polyester prepared from bis(2,6‐di‐tert‐butyl‐4‐chlorocarboxyphenyl) terephthalate and resorcinol had a ηinh (trichloroethylene) of 1.05 (0.5%, 30°C) and a possible melting point of 330°C (DSC). Tough, creasable films could be cast from trichloroethylene solution of this polymer. Attempts to observe or to trap the keto‐ketene that might result when 3,5‐di‐tert‐butyl‐4‐hydroxybenzoyl chloride is treated with base were unsuccessful.
Long branching in poly(vinyl acetate) and poly(vinyl alcohol). I. Crosslinking and crosslinking cleavage of poly(vinyl acetate)
Authors: Nozakura Shun‐Ichi , Morishima Yotaro , Murahashi Shunsuke 
Published: April 2003

AbstractA crosslinked network was formed by the reaction of partially saponified poly(vinyl acetate) and toluylene diisocyanate in benzene. The yield of gel was markedly dependent on the degree of saponification and the concentrations of polymer and diisocyanate. Crosslinked poly(vinyl alcohol) was obtained by treating the poly(vinyl acetate) with a catalytic amount of sodium hydroxide in methanol without any change of the urethane crosslinks. The crosslink based on the urethane linkage was quantitatively cleaved by acids, especially by hydrobromic acid, releasing polymers of the same molecular weight as the original.
Correlations to evaluate permeation of vapor and liquid hydrocarbons through polymer membranes
Authors: Leitão Dorodame Moura , Santos Marcos Luiz Dos 
Published: April 2003

AbstractIt has been shown in this investigation that the permeation of propane and propylene through polyethylene membranes exhibit a generalized behavior in the vicinity of the condensation point of the penetrant. Correlations to evaluate the permeation flux are presented.
Excluded‐volume effects in dilute polymer solutions. IV. Polyisobutylene
Authors: Matsumoto T. , Nishioka N. , Fujita H. 
Published: April 2003

AbstractStatistical radii of gyration, second virial coefficients, and intrinsic viscosities of sharp fractions (M̄w/M̄n ≈ 1.1) of polyisobutylene (PIB) covering a wide range of molecular weight (1.6 × 105 to 4.7 × 106) were determined in isoamyl isovalerate (IAIV) at a number of temperatures ranging from 20 to 60°C, in n‐heptane at 25°C, and in cyclohexane at 25°C by light‐scattering and viscosity measurements. It was found that IAIV at 22.1°C is a theta solvent for PIB. Analysis of the data by the methods described in preceding papers of this series indicated that, except for minor differences, the conclusions derived from similar studies with polychloroprene, polystyrene, and poly‐p‐methylstyrene hold equally for solutions of the typical linear polymer investigated here. In particular, no decisive evidence for the drainage effect was found.
Computerized measurement of viscoelastic properties of macromolecular solutions: Frequency dependence over and extended range of solvent viscosity
Authors: Massa Dennis J. , Schrag John L. 
Published: April 2003

AbstractThe modified Birnboim transducer and a computerized data acquisition and processing system (DAPS) for the measurement of viscoelastic properties of macromolecular solutions are described. The apparatus has a continuous frequency range from 0.01 to ca. 700 Hz and a viscosity range from 2 to ca. 30,000 poise (sample volume 1 to 1.5 cm2). Sample temperature is controlled to within 0.002°C from −30°C to +80°C. Working displacements are 102 to 104 Å. The DAPS is designed for precise determinations of the magnitudes and relative phasing of two sinusoidally time‐varying electrical signals (0.02%, 0.02°, respectively, for signals > 2 V peak) from 10−2 to 105 Hz. Cross‐correlation techniques are used for noise rejection. For frequencies below 30 Hz values of the storage (G') and loss (G″) components of the complex shear modulus (G*) of 1 dyne/cm2 are determined to within 10% and 4%, respectively, for liquids of moderately low viscosity. Proportionately higher measurement accuracies for typical values of G' and G″ and the wide frequency and viscosity ranges permit extrapolation to infinite dilution and studies of limited molecular flexibility for many polymer—solvent systems.
Kinetics of the dissociation of nonionic detergent micelles by a temperature‐jump technique
Authors: Lang Jacques , Eyring Edward M. 
Published: April 2003

AbstractThe rate of dissociation of a nonionic detergent, octylphenyl polyoxyethylene ether, was studied by a temperature‐jump technique. A relaxation process which is concentration‐dependent was observed. A linear relation between the reciprocal relaxation time and the detergent concentration above the critical micelle concentration was obtained, from which the rate constant of dissociation kn,n–1 of one molecule of detergent from the micelle has been determined. Values of kn,n–1 equal to 0.4 ± 0.05 and 73 ± 5 sec−1 at 24.8°C were obtained for detergents with 16 and 30 ethylene oxide units per molecule of surfactant, respectively, showing and increase of the rate constant of dissociation with the length of the hydrophilic‐head chain.
Ultimate tensile properties of elastomers. VII. Effect of crosslink density on time–temperature dependence
Authors: Smith Thor L. , Chu W. H. 
Published: April 2003

AbstractData on tensile strength and elongation at break for a series of Viton A‐HV vulcanizates are discussed. The data were obtained at various extension rates at temperatures from −5 to 230°C (25 ≲ T — Tg ≲ 260°C) on seven vulcanizates having crosslink densities ve (estimated from C1 in the Mooney‐Rivlin equation) from 0.46 × 10−5 to 24.4 × 10−5 mole/cm3. At an extension rate of 1 min−1, an increase in ve affects the tensile strength σb (based on the undeformed cross‐sectional area) and the true tensile strength σbσb (based on the cross‐sectional area of a deformed specimen) as follows: σb is essentially constant at a low temperature; it passes through a decided maximum at intermediate temperatures; and it increases to a plateau at elevated temperatures. In contrast, λbσb decreases markedly at all temperatures, an exception being the most lightly crosslinked vulcanizate(s). Application of time—temperature superposition to the ultimate‐property data gave log aT; its temperature dependence is that typical of nonpolar rubbery polymers. Data on the vulcanizates were compared in corresponding temperature states by plotting log 273σb/T, log 273λbσb/T, and (λb — 1)/(λb — 1)max against logtb/(tb)max, where tb is the temperature‐reduced time to break and (tb)max is the value at which the ultimate extension ratio λb attains its maximum, (λb)max. Except for the most lightly crosslink vulcanizate, the comparison shows that 273λbσb/T and (λb — 1)/(λb — 1)max are substantially independent of (or only weakly dependent on) crosslink density, that 273λb/T increases with ve, and that 273λb/T ∝︁ ve0.6 and λb ∝︁ ve−0.4 at a large value of tb/(tb)max.
Incompatibility of blocks in an isolated molecule of A‐B block copolymer
Authors: Pouchlý J. , Živný A. , Sikora A. 
Published: April 2003

AbstractThe problem of the segregation of subchains in an isolated molecule of an A‐B block copolymer is closely related to that of the mutually excluded volume of two chemically differing macromolecules. Therefore, by resorting to the “segment cloud” model used by Flory and Krigbaum to calculate the excluded volume, it was possible to derive an expression for the number of contacts between the two blocks in the same molecule. From the results of the calculation it follows that only partial block segregation can be expected unless the condensation of one of the subcoils to a dense globule occurs, owing to the effect of a poor solvent quality.
A semi‐empirical approach to the viscosities of polyelectrolyte solutions
Authors: Yuan L. , Dougherty T. J. , Stivala S. S. 
Published: April 2003

AbstractThe concentration dependence of the reduced viscosity of a number of polyelectrolytes was found to be adequately described by the equation

as long as the concentration is not too low. The parameter [η]∞ represents the intrinsic viscosity of the well‐shielded polyion and corresponds to values of [η] determined in salt solutions and may possibly correspond to the theory of Harris and Rice on polyion expansion. Heuristic arguments based in part on the work of Katchalsky et al. lead to a definite expression for the parameter k in terms of molecular properties. This result shows that the above equation is valid only for strong polyelectrolytes with constant activity coefficients of counterion. The calculated values of k agree well with experiment except when specific intramolecular interactions (e.g., internal hydrogen bonding) occur. For highly charged polyions we find, surprisingly, that k depends only on the properties of the polymer backbone and not on electrical properties.
Effect of pressure on gas permeability coefficients. A new application of “free volume” theory
Authors: Stern S. A. , Fang S.‐M. , Frisch H. L. 
Published: April 2003

AbstractThe present work is a continuation of a general study of the effect of pressure on gas and vapor permeation through nonporous polymeric membranes. Permeability coefficients have been measured for 1,1‐difluoroethylene (C2H2F2) and fluoroform (CHF3) in polyethylene at penetrant pressures up to 35 atm and at temperatures between ‐18 and 70°C. The permeability coefficient P̄ for the 1,1‐difluoroethylene—polyethylene system was found to increase with increasing pressure differential Δp across the membrane. Isothermal plots of log ΔP versus Δp are generally linear and can be represented by empirical relations of the form ΔP = P(0)exp{m Δp}, where P(0) and m are constants. The slope m of these isotherms decreases with increasing temperature. Plots of log P̄ versus Δp for the fluoroform—polyethylene system are also linear, but exhibit negative slopes, i.e., P̄ decreases with increasing Δp. An extension of Fujita's “free volume” theory of diffusion in polymers shows that the dependence of P̄ on pressure reflects how the free volume of the polymer is affected by this pressure. An increase in the penetrant pressure may result in two opposing effects: (a) the concentration of the penetrant dissolved in the membrane is increased, thereby increasing the free volume, and (b) the hydrostatic pressure on the membrane is also increased, which causes a decrease in the free volume. If the overall effect is an increase in the free volume of the polymer, then P̄ will also increase, and vice versa.
Crystallization of short aliphatic polymer chains. I. General chain‐folding behavior
Authors: Keller A. , Udagawa Y. 
Published: April 2003

AbstractShort aliphatic polymer chains of different lengths were prepared by degrading polyethylene samples of appropriately chosen initial fold lengths to the chain lengths which correspond to a single chain traverse through the lamella. The resulting dicarboxylic acids were either used as such for further crystallization experiments or were first converted into diiodides to remove polar endgroups. The resulting short polymers all crystallized by chain folding even if the chains (peak of distribution) were only 1.5–4 times the length of a traverse through the lamella. In the diiodides the fold length varied continuously with crystallization temperature, as is usual in high molecular weight material, but with the dicarboxylic acids such variation, while observable, was only small. The effect of the molecular weight on the fold length due to its influence on supercooling at a given crystallization temperature has become apparent. Renewed degradation with nitric acid and subsequent GPC analysis of the degradation products confirmed the folded nature of the chains in the above crystals. This analysis combined with experiments on the reactivity of chain ends has led to the picture that each chain folds completely, once, twice etc. so that both folds and ends are in the surface zone but are located at varying heights, as appropriate to the overall layer thickness for the molecular weight distribution in question. This picture is consistent with other concurrent work.
Effect of iodine on small‐angle X‐ray diffraction from drawn poly(ethylene terephthalate) film
Authors: Sakai Toyoko , Miyasaka Keizo , Ishikawa Kinzo 
Published: April 2003

AbstractThe effect of iodine sorption on the small‐angle x‐ray diffraction intensity is discussed in terms of the distribution of iodine sorbed in the amorphous regions of polymers. The change in the intensity of the peak corresponding to long periods is measured as a function of the iodine uptake in drawn, and annealed poly(ethylene terephthalate) films. A linear relation with slope K is observed between the square root of relative intensity and iodine uptake. The slope K varies with annealing conditions. Theoretical values calculated for models of the distribution of iodine in amorphous regions, are compared with the observed K. Results can be interpreted on the basis of a “concave” distribution of iodine, i.e., with sorption sites more numerous near a crystal surface than in the interior of an amorphous region.
Effect of aging on flow birefringence of poly(vinyl alcohol) and methyl cellulose solutions
Authors: Fujishige Shoei 
Published: April 2003

AbstractFlow birefringence experiments on aqueous solutions of poly(vinyl alcohol) and of methyl cellulose show that the optical anisotropy changes markedly during aging of the solution. The same effect can be obtained by adding alcohol to fresh aqueous methyl cellulose solutions. The flow birefringence was measured as a function of the velocity gradient on solutions with and without alcohol during the course of aging. The phenomena are attributed to intermolecular and intramolecular interactions between exposed hydroxyl groups of the polymer chains, as these are affected by a change in the degree of hydration during aging or by the addition of a strong hydrophilic agent such as an alcohol. Association or crystallization of the ordered polymer chains may occur and lead to a supermolecular structure in the solutions. By following Sadron's theory and making use of a polar diagram, it was concluded that, after aging or mixing with the additive, the solutions become optically heterogeneous and contain two different components with optical polarizabilities of the same [in poly (vinyl alcohol) solutions] or opposite (in methyl cellulose solutions) sign.
Poly(2,6‐diphenyl‐1,4‐phenyl oxide): Characterization by gel‐permeation chromatography, light scattering, and solution viscosity
Authors: Shultz A. R. , Bridgman A. L. , Hadsell E. M. , McCullough C. R. 
Published: April 2003

AbstractTen unfractionated poly(2,6‐diphenyl‐1,4‐phenylene oxide) samples were examined by gel permeation chromatography (GPC) and intrinsic viscosity [η] at 50°C in benzene, by intrinsic viscosity at 25°C in chloroform, and by light scattering at 30°C in chloroform. The GPC column was calibrated with ten narrow‐distribution polystyrenes and styrene monomer to yield a “universal” relation of log ([η]M) versus elution volume. GPC‐average molecular weights, defined as M̄gpc = \documentclass{article}\pagestyle{empty}\begin{document}$\Sigma w_i [\eta ]_i M_i /\Sigma w_i [\eta ]_i$\end{document}, wi denoting the weight fraction of polymer of molecular weight Mi, were computed from the GPC and [η] data on the polyethers. The M̄GPC were then compared with the weight‐average M̄w from light scattering. The intrinsic viscosity (dl/g) versus molecular weight relations for the unfractionated poly(2,6‐diphenyl‐1,4‐phenylene oxides) determined over the molecular weight range 14,000 ≤ M̄w ≤ 1,145,000 are log [η] = −3.494 + 0.609 log M̄w (chloroform, 25°C) and log [η] = −3.705 + 0.638 log M̄w (benzene, 50°C). The M̄w(GPC)/M̄n(GPC) ratios for the polymers in the molecular weight range 14,000 ≤ M̄w ≤ 123,000 approximate 1.5 according to computer integrations of the GPC curves with the use of the “universal” calibration and the measured log [η] versus log M̄w relation. The higher molecular weight polymers (326,000 ≤ M̄w ≤ 1,145,000) show slightly broadened distributions.