bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer solid electrolytes from the PEG‐PMMA‐LiCF3SO3 system
Authors: Such K. , Stevens J. R. , Wieczorek W. , Siekierski M. , Florjanczyk Z. 
Published: April 2003

AbstractHighly conductive solid polymeric electrolytes based upon low molecular weight poly(ethylene glycol) and ethylene oxide/propylene oxide copolymers blended with up to 50% by volume of poly(methyl methacrylate) have been synthesized using LiCF3SO3 (25:1 ether oxygen to cation ratio). Room‐temperature ionic conductivities were measured to be in the range 10−4 to 10−5 S/cm for poly(methyl methacrylate) concentrations up to 30% by volume. In some cases, the addition of the poly(methyl methacrylate) enhanced the conductivity. All of the electrolytes studied were either amorphous or crystallized below 0°C. The variation of conductivity with temperature and polymer composition was measured and the results were analyzed in terms of effective medium theory and semiempirical considerations. Ionic transport is coupled to the structural relaxation of the polymer segments. At lower temperatures activated processes were required. Both charge carrier mobility and charge concentration were found to contribute to conduction. The effective medium theory quantitatively describes conductivities of amorphous heterogenous systems of limited miscibility (microphase separation) quite well. For miscible or partially crystalline systems other effects not incorporated in this theory play an important role, and conductivities are measured to be higher than theoretically predicted. © 1994 John Wiley & Sons, Inc.
Some theoretical considerations on diffusion‐controlled one‐chain polymerization in two‐dimensional systems
Authors: Raudino Antonio 
Published: April 2003

AbstractA simple model has been developed to investigate the differences between 2D and 3D diffusion‐controlled polymerization kinetics. Besides the different analytical structure of 2D and 3D diffusion equation, the model takes into account the dynamics of the polymer chemically reacting end and the restricted motion of the diffusing monomers in a growing polymer network. These effects are strongly related to the dimensionality of the system and may contribute to modulate the polymerization rate. Theoretical considerations suggest different behavior when 2D polymerization takes place in a poor solvent, whereas minor differences should be present in good solvents and 3D systems. © 1994 John Wiley & Sons, Inc.
Lamellar thickness of crystallizable ethene runs in ethene‐propene copolymers by solid state NMR
Authors: Clayden Nigel J. 
Published: April 2003

AbstractCrystallizable runs of ethene in ethene‐propene copolymers can be identified in 13C CPMAS NMR spectra as a resonance at 33 ppm. In the absence of spin diffusion, the variation in intensity of this resonance with a 1H spin lock will reflect the intrinsic TH1ρ. Spin diffusion leads to a more complex relaxation decay, which reflects the local polymer morphology. Simulations of the spin diffusion process have been carried out for a simplified two‐phase model for the morphology with the aim of determining whether the lamellar thickness of the crystalline and amorphous regions can be found from the TH1ρ observed via the 13C NMR spectrum. Calculations covering the expected range of the input parameters, namely the spin diffusion coefficients, domain lengths, and intrinsic relaxation times, show that, providing the intrinsic relaxation time in the amorphous phase is known, an accurate estimate of the crystalline and amorphous lamellar thicknesses can be made. Analysis of simulated TH1ρ decays indicate that, in general, the time constant of the fastest decaying component can be identified with the intrinsic relaxation time of the amorphous phase. © 1994 John Wiley & Sons, Inc.
Sorption and transport of water vapor in alginic acid, sodium alginate, and alginate‐cobalt complex films
Authors: Hirai Asako , Odani Hisashi 
Published: April 2003

AbstractThe sorption and the transport of water vapor in films of alginic acid (G1), sodium alginate (G1Na), and alginate‐cobalt complex (G1Co) were studied at 30°C by employing the weighing method. Sorption isotherms for all films of G1, G1Na, G1Co were of type II in the Brunauer's classification. The integral absorption from, and desorption to, zero pressure were non‐Fickian type for all films studied. The mean permeability coefficient P, which was determined by the cup method, increased with the increase of vapor pressure, especially in the low vapor pressure region. P for G1Na was much higher than that for G1, which mainly reflects more hygroscopic nature of G1Na than that of G1. The values of P for G1Co were lower than those for G1 at lower pressures and then approached those for G1 at higher vapor pressures. Integral diffusion coefficient D evaluated as P/S, where the solubility coefficient S was evaluated from sorption isotherms, increased rapidly with increasing water concentration and then leveled off. In the concentration region studied, the magnitude of D and its dependence on concentration for H2O‐G1Na system did not differ much from those for H2O‐G1 system. D for H2O‐G1Co system was much lower than that for H2O‐G1 system. © 1994 John Wiley & Sons, Inc.
Effect of side‐chain length on charge mobilities in neutral poly(3‐alkylthiophene)s: Determination from dielectric measurement
Authors: Chen Show‐An , Liao Chien‐Shiun 
Published: April 2003

AbstractFor neutral poly(3‐alkylthiophene)s (P3ATs), the electric modulus formalism of dielectric relaxation measurement together with the use of nonexponential decay function can be applied to describe the behavior of conductivity relaxation and carrier transport. The charge mobilities of neutral P3ATs calculated from conductivity relaxation with the use of the defect‐diffusion model are in agreement with the data from field‐effect transistor measurement. The temperature dependence of charge mobility exhibits a local maximum right after the end of glass transition region, which can be attributed to the transition of soft conformons in the disordered phase to localized conformons. The charge mobilities and activation energies of mobilities for P3ATs are dependent on conjugation length and volume fraction of conducting units. © 1994 John Wiley & Sons, Inc.
A detailed study of sorption equilibria and kinetics of a model disperse dye in cellulose acetate
Authors: Papadokostaki K. G. , Petropoulos J. H. 
Published: April 2003

AbstractA detailed investigation of the sorption of 4‐aminoazobenzene by cellulose acetate films from aqueous solution is reported. Sorption isotherms at 75 and 60°C were linear up to saturation, in agreement with previous findings that have led to the conclusion that cellulose acetate‐disperse dye systems are thermodynamically ideal. Thermodynamic analysis of these data also gave results consistent with such previous findings. The isotherms for 45 and 25°C, on the other hand, exhibited increasing curvature, in line with similar recent findings for a variety of hydrophobic polymer‐disperse dye systems, and consistent with the presence of some strong absorption sites. However, the situation appears to be more complex than envisaged by simple dual‐mode sorption theory. Early time desorption kinetic data were found to be consistent with Fick's law, with no indication of any significant dependence of the diffusion coefficient D on concentration (in the medium‐ to high‐concentration range) or on film thickness. On the other hand, D was affected significantly by the history of film formation, the method of introducing the dye or heat treatment of the film. The origin of these effects was traced by DSC to definite microstructural differences. Late time kinetic data deviated significantly from the theoretical predictions based on the corresponding early time data, indicating a progressive slowdown of the desorption process. The deviations in question were generally more marked at higher temperature or film thickness, or when dyeing had been effected from the vapor phase, and were attributed to slow release of strongly adsorbed dye molecules. © 1994 John Wiley & Sons, Inc.
The growth and interaction of conjugated polymer chains, the unpaired electron localization
Authors: Gordon Delyara A. , Mikhailov Alfa I. 
Published: April 2003

AbstractAn ESR method was used to study the structure of the macroradical of the propagating chain Rp in the low‐temperature, solid‐phase polymerization of p‐diethynylbenzene (DEB). The ESR spectra for γ‐irradiated DEB samples and those of DEB deuterated in the ethynyl group showed that in the range 77–230 K, the unpaired electron of the macroradical was localized on one of the monomer links. At 230–310 K, its delocalization in a polyconjugated system took place because of addition of a linear macroradical to a double bond of a polymer molecule. The encounter of the macroradical with double bond probably occurs as polymer chain propagation. © 1994 John Wiley & Sons, Inc.
ATR analysis of the oil‐absorption ability of a two‐part epoxy adhesive on oil‐contaminated metal substrates
Authors: Hong S. G. , Shu H. X. 
Published: April 2003

AbstractThe oil absorption of a room‐temperature‐cured, two‐part epoxy adhesive on three metal substrates, cold‐rolled steel (CRS), 2024‐aluminum, and electrogalvanized steel (EGS), was studied using attenuated total reflection infrared spectroscopy (ATR). From relative absorbance ratios calculated from ATR spectra taken at different penetration depths, it was determined that the effectiveness of the adhesive in replacing the oil from the metal surfaces followed in the order of 2024‐Al > CRS > EGS. As thick as 20 microns oil could be absorbed from the 2024‐Al and CRS surfaces, but much less oil could be absorbed from the oiled EGS substrate. However, the heat applied during cure could greatly help the adhesive absorb oil from the EGS substrate. Distributions of adhesive functional groups with respect to penetration depths were found in adhesive layers adjacent to metal surfaces. The abundance of curing agents in the adhesive/EGS interfacial region resulted in the incomplete oil absorption observed on the oiled EGS substrate. The results from ATR also showed that the oil did not inhibit the cure of the adhesive in the bulk. © 1994 John Wiley & Sons, Inc.
In situ X‐ray scattering studies of lyotropic liquid crystalline PBO and PBZT monofilament drawing
Authors: Radler M. J. , Landes B. G. , Nolan S. J. , Broomall C. F. , Chritz T. C. , Rudolf P. R. , Mills M. E. , Bubeck R. A. 
Published: April 2003

AbstractThe results of a series of novel synchrontron‐based in situ x‐ray scattering experiments of monofilament fiber drawing from lyotropic solutions of poly(cis‐benzoxazole) (PBO) and poly(trans‐benzothiazole) (PBZT) are reported. The purpose of the study is to determine orientation and microstructure development in the draw zone as a function of shear rate in the capillary die, and spin draw ratio (SDR). The transition of the extrudate from opaque to the transparent is complete at about a SDR = 3 and f of 0.9. The filament orientation parameter (f) was found to depend strongly on spin draw ratio, but not shear rate. The orientation was found to increase down the extrudate toward completion of the draw down as one proceeds further from the die face up to an extrudate length of 3.8 cm. Coherence lengths on the order of 19 nm (axial), and 4.5 nm (lateral) have been observed. These “microdomain” sizes are consistent with the “crystallite” sizes typically observed in coagulated fiber. The occurrence of these microdomains in the draw zone as a precursor to the microfibrillar structure is believed to be the origin of low filament compressive strength. © 1994 John Wiley & Sons, Inc.
Axial X‐ray scattering on high‐performance polymeric fibers
Authors: Bai S. J. 
Published: April 2003

AbstractHigh‐temperature polymers were spum from liquid‐crystalline solutions into fibers of superior thermal stability and mechanical properties. Fibers of two extended‐chain polymers poly(p‐phenyleneterephthalamide), PPTA, and poly‐2,5‐benzoxazole, ABPBO, as well as a rod‐like polymer poly(p‐phenylenebenzobisoxazole), PBO, were examined by axial x‐ray scattering. Both wide‐angle scattering and small‐angle scattering were performed with CuKα radiation aiming along the fiber axis (c‐axis) for structural information on the a‐b lattice plane. In addition to previously reported lattice structure, the PPTA fibers (Kevlar® 29, 49, and 149) showed strong [004] and a [022] reflections suggesting that segments of the PPTA molecules were transverse to the fiber axis. This unique fiber structure is more prominent and the void content is less for the PPTA fibers with higher tensile modulus, (i.e., Kevlar® 149 > Kevlar® 49 > Kevlar® 29). Similar measurements on thermally annealed ABPBO and PBO fibers showed no [00l], [h0l], or [0kl] reflection indicative of a truly uniaxial molecular orientation. Evidence of microfibrillar order was discovered for the Kevlar® fibers and the ABPBO fiber. Results of conventional x‐ray scattering on these fibers were compared and reconciled. © 1994 John Wiley & Sons, Inc.
Free volume, hole theory and thermal properties
Authors: Simha Robert , Carri Gustavo 
Published: April 2003

AbstractFree volume ideas have been employed extensively in the interpretation of equilibrium processes and as a measure of molecular mobility. More recently, the vacancy fraction h, defined in our hole theory, has served to provide a link between diverse processes. This raises a question regarding the relation between the van der Waals type of free volume and h. As an important and useful result, valid for polymers and low molar mass fluids, simple relations are obtained between the van der Waals volume Vw, computed according to Bondi's structural rules, and the scaling volume V* in the hole theory. This is defined by the intersegmental potential and extracted from the equation of state. In turn, this result enables us to compute the corresponding scaling temperature T*. In this manner the theory predicts the volume‐temperature function for a melt, based on a single experimental datum. Corresponding considerations are presented for the glassy state. The quantitative relation between the van der Waals type of free volume vf and h derived makes it possible to reconsider various empirical correlations involving the former. © 1994 John Wiley & Sons, Inc.
The morphology of gel‐spun polyethylene fibers, investigated by solid‐state 13C NMR
Authors: Chen Wei , Fu Yigang , Wunderlich Bernhard , Cheng Jinlong 
Published: April 2003

AbstractGel‐spun polyethylene fibers were analyzed at room temperature with 13C NMR, using both, CP‐MAS and BILEV (Bloch‐decay with two‐level decoupling). The analysis shows the existence of three different components in the fiber sample—a crystal component, an amorphous component and a third component, named the oriented, mobile component. This latter component has a 13 C chemical shift that is similar to the crystalline chemical shift, but with a mobility, expressed by T1, that is closer to the amorphous component. The chemical shift and T1 are as follows: 34.06 ppm and 28.1 s for the crystalline part; 31.70 ppm and 0.3 s for the amorphous part; and 34.06 ppm and 1.8 s for the oriented mobile component. The percentages are 63.2% crystalline; 34.0% oriented mobile, 2.8% amorphous component. Using proton spin‐diffusion measurements, it was possible to estimate the domain size of the crystalline and oriented mobile components to be 62.8 and 13.2 nm, respectively, in agreement with the results of a full‐pattern x‐ray study on the same sample. After melting of the fiber at 450 K and recrystallinzation on cooling, the oriented, mobile component is dramatically reduced. © 1994 John Wiley & Sons, Inc.
Fluorescence nonradiative energy transfer in bulk polymer and miscible and phase‐separated polymer blends: A quantitative analysis including correlation effects
Authors: Mendelsohn Alice S. , Torkelson John M. , de la Cruz Monica Olvera 
Published: April 2003

AbstractA theoretical analysis has been developed to predict fluorescence nonradiative energy transfer (NBET) behavior in homogeneous and phase‐separated polymer blends. Conditions where intermolecular correlations need to be included are examined by first investigating the effect of including intermolecular correlations in predictions of NRET behavior in donor and trap (acceptor) end‐labeled polymer melts. Donor fluorescence decays and energy transfer efficiencies are predicted for several different polymer systems using donor‐trap intermolecular correlations in the theoretical analysis. These results are compared quantitatively to the same predictions recalculated without correlations and demonstrate the need to consider the effects of correlations when analyzing NRET measurements used for quantitative study of phase behavior. For the nonradiative energy transfer systems investigated here, correlation effects can often result in substantial differences, up to 60% as compared to the uncorrelated case, in predictions of relative energy transfer efficiency for bulk polymer. In the case of the blends, the effect of including intermolecular correlations is strongly a function of composition. A two‐phase model is proposed to establish a quantitative method for relating energy transfer efficiency to phase‐separated blend composition, and it is demonstrated that significant errors in interpretation of experimental NRET data may result if correlation effects are not included. © 1994 John Wiley & Sons, Inc.
Phase behavior in mixtures of a homopolymer and a block copolymer 1. FTIR and DSC studies
Authors: Xie Rui , Yang Bingxing , Jiang Bingzheng 
Published: April 2003

AbstractMiscibility in blends of three styrene‐butadiene‐styrene and one styrene‐isoprene‐styrene triblock copolymers containing 28%, 30%, 48%, and 14% by weight of polystyrene, respectively, with poly(vinyl methyl ether) (PVME) were investigated by FTIR spectroscopy and differential scanning calorimetry (DSC). It was found from the optical clarity and the glass transition temperature behavior that the blends show miscibility for each kind of triblock copolymers below a certain concentration of PVME. The concentration range to show miscibility becomes wider as the polystyrene content and molecular weight of PS segment in the triblock copolymers increase. From the FTIR results, the relative peak intensity of the 1100 cm‐1 region due to COCH3 band of PVME and peak position of 698 cm‐1 region due to phenyl ring are sensitive to the miscibility of SBS(SIS)/PVME blends. The results show that the miscibility in SBS(SIS)/PVME blends is greatly affected by the composition of the copolymers and the polystyrene content in the triblock copolymers. Molecular weights of polystyrene segments have also affected the miscibility of the blends. ©1995 John Wiley & Sons, Inc.
Measurement of thermal diffusivity and specific heat capacity of polymers by laser flash method
Authors: Agari Y. , Ueda A. , Nagai S. 
Published: April 2003

AbstractWe measured thermal diffusivity and heat capacity of polymers by laser flash method, and the effects of measurement condition and sample size on the accuracy of the measurement are discussed. Thermal diffusivities of PTFE films with thickness 200–500 μm were the same as those data that have been reported. But, the data for film thickness less than 200 μm have to be corrected by an equation to cancel thermal resistance between sample film and graphite layers for receiving light and detecting temperature. Thermal diffusivity was almost unaffected by the size of area vertical to the direction of laser pulse, because heat flow for the direction could be negligible. Specific heat capacity of polymer film was exactly measured at room temperature, provided that low absorbed energy (< 0.3 J) and enough sample mass (> 25 mg) were satisfied as measuring conditions. Thermal diffusivity curve of PS or PC versus temperature had a terrace around Tg, whereas that of PE decreased monotonously with increasing in temperature until Tm. Further, we estimated relative specific heat capacity (RCp) by calculating ratios of heat capacities at various temperatures to the one at 299 K. RCp for PS obtained by laser flash method was larger than that obtained by DSC method, whereas the RCps for PE obtained by the both methods agreed with one another until Tm (305 K). RCp for PS decreased linearly, with increase in temperature after it increased linearly until Tg (389 K), showing similarity to temperature dependency of thermal conductivity. RCp for PE also decreased until Tm, similar to thermal conductivity. ©1995 John Wiley & Sons, Inc.
Aggregation of sulfonated poly(p‐phenylene terephthalamide) in dilute solutions
Authors: Chu Evan Y. , Xu Z. S. , Lee C. M. , Sek Cindy K. F. , Okamoto Y. , Pearce E. M. , Kwei T. K. 
Published: April 2003

AbstractThe viscosities of dilute solutions of poly(p‐phenylene terephthalamide), PPTS, in dimethylacetamide, water, and their mixtures were determined. The reduced viscosity plot in dimethylacetamide shows a negative slope. When the water content in the mixed solvent in 90% or higher, there is an upswing in the reduced viscosity values at concentrations below 0.1 g/dL. The latter behavior suggests a “polyelectrolyte” effect. However, an association model was found to be able to explain the viscosity behaviors in both solvents. ©1995 John Wiley & Sons, Inc.
Reactive blending via metal‐ligand coordination
Authors: Belfiore Laurence A. , McCurdie Mary Pat 
Published: April 2003

Abstractd‐Block transition‐metal‐containing polymer blends which form coordination complexes are described in this treatise. The model compounds are zinc acetate dihydrate, copper acetate dihydrate, nickel acetate tetrahydrate, cobalt chloride hexahydrate, palladium chloride bis (acetonitrile), and the dimer of dichlorotricarbonylruthenium (II). Two classes of ligands are of interest. Poly (4‐vinylpyridine), P4VP, and copolymers that contain 4‐vinylpyridine repeat units form complexes with zinc, copper, nickel, cobalt, and ruthenium salts. Atactic 1,2‐polybutadiene contains olefinic sidegroups that displace weakly bound acetonitrile ligands and coordinate to palladium chloride. Thermal analysis via differential scanning calorimetry suggests that the glass transition temperature of the polymeric ligand is enhanced by these low‐molecular‐weight transition‐metal salts in binary and ternary blends. In some cases, d‐block salts function as transition‐metal compatibilizers for copolymers that would otherwise be immiscible. The isothermal ternary phase diagram for polybutadiene with palladium chloride highlights regions of gelation, precipitation, and transparent solutions during blend preparation in tetrahydrofuran. Fourier transform infrared spectroscopy provides molecular‐level data that support the concept of polymeric coordination complexes. High‐resolution carbon‐13 solid‐state NMR spectroscopy identifies (1) near‐neighbor interactions between polymeric pyridine ligands and the ruthenium salt, and (2) a considerable reduction in the molecular mobility of the polybutadiene chain backbone when it forms a coordination complex with palladium chloride. The elastic modulus of polybutadiene increases by three orders of magnitude when the palladium salt concentration is 4 mol % in a solid‐state glassy film. A thermodynamic interpretation of ligand field stabilization energies appropriate to tetrahedral cobalt and octahedral nickel complexes is employed to estimate the synergistic enhancement of the glass transition temperature, particularly when coordination crosslinks are present. ©1995 John Wiley & Sons, Inc.