bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of solvent treatment on crystallization kinetics of poly(p‐phenylene sulfide)
Authors: Woo E. M. , Chen J.‐M. 
Published: April 2003

AbstractIsothermal melt crystallization kinetics were investigated by differential scanning calorimetry (DSC) for virgin and α‐chloronaphthalene solvent‐treated poly(phenylene sulfide) (PPS) systems. The overall crystallization rates were found to be much faster for the solvent‐treated PPS than for the virgin neat PPS. Additionally, the Avrami crystallization plot for the solvent‐treated PPS samples appeared as two straight portions with an apparent discontinuity, but as a continuous straight line for the virgin PPS system. After the treatment of solvent dissolution and subsequent drying, the residual trace α‐chloronaphthalene, upon being quenched to the crystallization temperatures, initiated some localized solvent‐induced nuclei‐like crystals in PPS. It was the nuclei that enhanced secondary crystallization in treated PPS during the second stage, and the higher extents of secondary crystallization in the solvent‐treated PPS caused the apparent discontinuous break in the Avrami plots. The causes for the difference were explained and the mechanism of the sequential primary/secondary crystallization kinetics for the solvent‐treated PPS was satisfactorily described with a proposed series‐parallel crystallization model. ©1995 John Wiley & Sons, Inc.
Water sorption in poly(zwitterions) of the ammonioalkoxydicyanoethenolate type
Authors: Galin J. C. , Galin M. 
Published: April 2003

AbstractWater sorption by amorphous (meth)acrylic poly(zwitterions)‐bearing quaternary ammonioalkoxydicyanoethenolate side groups , dipole moment μ(D) = 25.9 and 30.8 for p = 2 and 3, respectively was studied at 23°C over a broad range of water activity a (0.14–0.98). Water diffusion is nearly Fickian (Ds = 5.9 10−7 cm2.s−1 for a = 0.63) and the sorption isotherms may be quantitatively analyzed according to the Guggenheim‐Anderson‐De Boer equation for a multilayer process characterized by a number of site‐bound water molecules per monomeric unit, nm ⋑ 0.7. The Flory χ interaction parameter is a strongly increasing function of the water content in the glassy hydrated systems and it always remains higher than 0.75. Clustering of water molecules (Zimm‐Lundberg theory) is never observed. Differential scanning calorimetry allows to quantify nonfreezable bound water (type I) of strong plasticization efficiency, n(I) = 2.8 mol. of water per monomeric unit, and it points out the quasisimultaneous emergence of low amounts of freezable bound water (type II) crystallizing at −40°C and melting at −1°C and of bulkfree water (type III, n(II)/n(III) ⋑ 0.1). All these typical features distinguish these rather hydrophobic poly(zwitterions) from their hydrophilic homologues of the quaternary ammoniopropanesulfonate type . © 1995 John Wiley & Sons, Inc.
Structural data and thermal studies on nylon‐12,10
Authors: Franco Lourdes , Puiggalí Jordi 
Published: April 2003

AbstractThe structure and morphology of Nylon‐12, 10 lamellar crystals has been investigated using transmission electron microscopy, selected area electron diffraction, and x‐ray diffraction. Additional data have been obtained from uniaxially oriented fibers. The unit cell parameters of two crystalline structures have been determined. They are similar to those usually found in other polyamides (α and β form). Calorimetric (DSC) studies on nylon 12, 10 were also carried out. Melting curves indicate that changes in the internal structure occur when scanning speeds less than 80°C min−1 are used. ©1995 John Wiley & Sons, Inc.
Rodlike/flexible polyimide composite films prepared from soluble poly(amic diethyl ester) precursors: Miscibility, structure, and properties
Authors: Kim Y. , Ree M. , Chang T. , Ha C. S. , Nunes T. L. , Lin J. S. 
Published: April 2003

AbstractHomogeneous precursor/precursor solutions with various compositions were obtained with appreciably high solid contents in N‐methyl‐2‐pyrrolidone from soluble poly(amic diethyl ester) precursors of rodlike poly(p‐phenylene biphenyltetracarboximide) (BPDA‐PDA) and flexible poly(4,4′‐oxydiphenylene biphenyltetracarboximide) (BPDA‐ODA), which are hydrolytically more stable as well as more soluble than the corresponding poly(amic acid)s being equilibrated with the constituent monomers. Both optical microscopic and light scattering measurements showed that the dried precursor blend films and resultant polyimide composite films were optically transparent, regardless of compositions and process conditions. The composite films showed a single Tg behavior. However, for the composite of 30 wt % BPDA‐PDA dispersed in the matrix of 70 wt % BPDA‐ODA, a smectic crystalline‐like aggregation of the BPDA‐PDA component was detected on wide‐angle x‐ray diffraction patterns, indicative of microscopic phase separation between the two components. This phase separation was not detected on the optical microscopy, light scattering, and dynamic mechanical thermal analysis because of their resolution limits: Optical microscopy has a resolution of submicrometers, whereas dynamic mechanical thermal analysis and light scattering have a resolution of ca. 50 Å. Therefore, it is speculated that in the composite films BPDA‐PDA and BPDA‐ODA polyimide molecules have demixed on the scale of a few nanometers. The mean long periodicity, which was estimated from the small‐angle x‐ray scattering pattern, varied from 134 to 170 Å as the content of BPDA‐ODA component increased. In addition, mechanical properties of the composite films were characterized. ©1995 John Wiley & Sons, Inc.
Cellulose‐polyamide 66 blends. Part II: Mechanical behavior
Authors: Ramirez M. Garcia , Cavaillé J. Y. , Dufresne A. , Tékély P. 
Published: April 2003

AbstractBlends of the natural polymer cellulose with a synthetic polymer, polyamide 66, are studied in order to determine if the expected strong interaction between them, due to hydrogen bonds, could improve their mechanical properties such as strength and elongation at break. In a previous work {Part I, J. Polym. Sci. Polym. Phys., 32, 1437 (1994)}, the preparation technique and the characterization of cellulose‐polyamide 66 (PA66) blends were described in detail. Several samples in the composition range between 0 to 70 wt % of PA66 were carefully dried and examined using dynamic mechanical and tensile tests. Based on previous work a new percolation model has been developed. It takes both linear and nonlinear mechanical behaviors into account and allows for the effect of adhesion between material domains. From comparison between experimental and predicted data, it is concluded that a partial miscibility between the amorphous phases of cellulose and PA66 exists and is responsible for a strong adhesion at their interface. Solid‐state 13C nuclear magnetic resonance has also been used to study these samples and supports the existence of strong interactions between both homopolymers. © 1995 John Wiley & Sons, Inc.
A detailed study of the viscoelastic nature of vapor sorption and transport in a cellulosic polymer. II. Sorption and longitudinal swelling kinetic correlations
Authors: Sanopoulou M. , Roussis P. P. , Petropoulos J. H. 
Published: April 2003

AbstractLongitudinal swelling kinetics of cellulose acetate films sorbing acetone vapor at 30°C were studied under various conditions and correlated with the corresponding sorption kinetic measurements reported in Part I. The results were analyzed in the light of (1) previous theoretical studies of simple viscoelastic polymer‐penetrant model systems and (2) mechanical stress‐strain data on the cellulose acetate‐acetone system, which are also reported here. The conclusions drawn from this analysis confirm and/or amplify (particularly as regards the effect of longitudinal differential swelling stresses) our previous interpretations based on sorption kinetic analysis, concerning the physical nature and causes of various features of the non‐Fickian kinetic behavior of cellulosic polymer‐micromolecular penetrant systems. History‐dependent long‐term aging effects were also observed and investigated. © 1995 John Wiley & Sons, Inc.
Mechanical properties of dual‐phase polymer electrolytes prepared from poly(styrene‐co‐butadiene) rubber/poly(acrylonitrile‐co‐butadiene) rubber mixed latices
Authors: Ichino Toshihiro , Takeshita Yukitoshi , Nishi Shiro 
Published: April 2003

AbstractMechanical properties of two dual‐phase polymer electrolytes (DPEs), prepared from poly(styrene‐co‐butadiene) rubber (SBR) and poly(acrylonitrile‐co‐butadiene) rubber (NBR) latices, are studied. Both DPEs are composed of an SBR supporting phase and an ionconductive phase of NBR/lithium salt solution. The first DPE maintains a tensile strength of 0.5 MPa and elongation of 280% with an ionic conductivity of 10−3 S/cm. Although the glass transition relaxations based on the dual‐phase structure are not resolved in this DPE because of the proximity of the glass transition temperatures of the SBR and NBR, the glass transition shifts to a lower temperature due to the plasticization by the lithium salt solution. In the second DPE, two distinctive glass transition relaxations, corresponding to the SBR and NBR phases, are observed in the viscoelasticity versus temperature measurement, indicating the dual‐phase structure. A simple equivalent mechanical model, which is modified from the Takayanagi model, is introduced to elucidate the mechanical behavior of the dual‐phase structure in the second DPE. According to this model, 8% of DPE is a mechanically continuous SBR phase in the tensile direction, which effectively gives mechanical support to the DPE. © 1995 John Wiley & Sons, Inc.
Hysteresis loss as a measure of metal–rubber adhesion
Authors: Bhattacharya Tinku , De S. K. 
Published: April 2003

AbstractAs in the case of reinforcing filler‐induced increase in hysteresis in rubbers, placement of aluminum (A1) foil to the surface of a rubber blend of epichlorohydrin rubber and carboxylated nitrile base induces increased hysteresis of the rubber due to adhesion between Al and the rubber blend. Changes in hysteresis loss due to Al foil can be correlated with the peel strength of Al‐rubber‐Al joints. © 1995 John Wiley & Sons, Inc.
High‐quality polythiophene films prepared by electropolymerization of thiophene in BF3‐ethyl ether solution
Authors: Li Cun , Shi Gaoquan , Xue Gi , Jin Shi , Yu Bo , Yang Sijun 
Published: April 2003

AbstractPolythiophene films have been deposited on a platinum electrode surface by direct oxidation of thiophene in BF3‐ethyl ether solution containing a controlled amount of water (5 mM). The electric and mechanical properties of the films were studied. Experimental results demonstrated that the films prepared at low applied potentials were semiconductors with conductivities in the order of 10−1 s cm−1. The strengths of these films were high and comparable to those of some widely used engineering plastics such as poly(propylene) and poly(vinyl acetate). The conductivities of the PT films varied with the value of applied potential used for electrolysis and passed through a maximum of 19.13 s cm−1 at +1.6 V. At a given applied potential, low experimental temperature, and monomer concentration led to formation of films with high quality. © 1995 John Wiley & Sons, Inc.
Excitation energy transfer in poly(p‐phenylphenylenevinylene) determined by polarized fluorescence spectroscopy
Authors: Damerau T. , Hennecke M. 
Published: April 2003

AbstractPolarized fluorescence spectroscopy is used to investigate the photophysical behavior of poly(p‐phenylphenylenevinylene) (PPPV) in polystyrene matrix in comparison with oligomeric model compounds. For this purpose PPPV is modeled by a chain consisting of a distribution of independent oligomeric segments. Excitation energy transfer (EET) between the segments depends on the wavelength of excitation, not only for transfer along an isolated polymer chain, but also for intermolecular transfer at high concentration of PPPV. The spatial range of EET, as indicated by fluorescence depolarization, is reduced for excitation at the long wavelength edge of the absorption spectrum (“red‐edge‐effect”). © 1995 John Wiley & Sons, Inc.
Osmotic deswelling of weakly charged poly(acrylic acid) solutions and gels
Authors: Silberberg‐Bouhnik Myriam , Ramon Ory , Ladyzhinski Ilya , Mizrahi Shimon , Cohen Yachin 
Published: April 2003

AbstractThe osmotic pressure of weakly charged aqueous poly(acrylic acid) (PAA) solutions and the swelling pressure PAA gels were studied by osmotic deswelling at different degrees of ionization (α). In solution, the osmotic pressure was found to scale linearly with concentration, whereas the scaling power of the swelling pressure of gels was higher (1.66). The effect of the ionization degree on the osmotic coefficient in PAA solutions was in agreement with the theory of Borue and Erukhimovich [Macromolecules, 21, 3240 (1988)]. Ionization increases the swelling capacity of the PAA gels until a plateau is reached at about 35% neutralization. The concentration at equilibrium swelling scales as Ce ∼ α−0.6. The contribution of the network to the gel swelling pressure is evaluated by subtracting the osmotic pressure of the polymer solution at the same concentration and degree of ionization. In swollen gels the extended network opposes swelling. As the gel is osmotically deswelled, a state of zero network pressure exists at a certain concentration, below which the network elasticity favors swelling. The crossover concentration shifts to lower values as the degrees of ionization increases. © 1995 John Wiley & Sons, Inc.
Small‐angle X‐ray scattering study of liquid crystalline polycarbonates based on α‐methyl stilbene mesogen and methylene‐containing flexible spacer
Authors: Cheng Yao‐Yi , Cebe Peggy , Capel Malcolm , Schreuder‐Gibson Heidi , Bluhm Aaron , Yeomans Walter 
Published: April 2003

AbstractCrystallization and melting behavior are studied by small‐angle X‐ray scattering (SAXS) for a series of recently synthesized monotropic liquid crystalline polycarbonates based on α‐methyl stilbene mesogen and methylene flexible spacer. The one‐dimensional electron density correlation function is used to obtain long period, crystal thickness, and linear crystallinity from the Lorentz‐corrected SAXS intensity. Changes in these parameters during nonisothermal crystallization and melting are explained by a model of dual crystal populations. The primary crystals form first using the liquid crystalline phase as crystal nuclei, while smaller and less perfect crystals form later from the isotropic phase at low temperature. The results of the real‐time SAXS study of isothermal crystallization also support the view that the nematic phase serves as crystal nuclei for fast crystallization. An odd‐even effect in crystal thickness and linear crystallinity is observed in all the SAXS experiments mentioned above. The results of this study and our complementary wide‐angle X‐ray scattering (WAXS) investigation show clearly that the difference in the position of the neighboring carbonate dipoles on a chain affects structural organization both at the unit cell level and at the level of the crystal in these monotropic LCPs. © 1995 John Wiley & Sons, Inc.
Distribution of chain ends at the surface of a polymer melt: Compensation effects and surface tension
Authors: Wu David T. , Fredrickson Glenn H. , Carton Jean‐Pierre , Ajdari Armand , Leibler Ludwik 
Published: April 2003

AbstractWe consider the surface of a nearly incompressible polymer melt, extending the usual ground‐state analysis of self‐consistent field theory to describe finite length polymers in the ground‐state potential. To maintain self‐consistency, further corrections to the potential are calculated within linear response theory. From this, we find an excess of ends near the surface, followed by a compensating depletion on the Rg length scale, which relies crucially on the finite compressibility of the melt. The attraction of ends to the surface can be described as resulting from a surface potential for ends with a strength on the order of kBT. Our results address the long‐standing controversies of the distribution of chain ends, the chain‐length dependence of the surface tension, and the interaction between objects immersed in a melt. © 1995 John Wiley & Sons, Inc.
Investigation of dielectric relaxations associated with the glass transition of vinylidene fluoride and trifluoroethylene copolymers by thermally stimulated current
Authors: Teyssèdre G. , Bernès A. , Lacabanne C. 
Published: April 2003

AbstractThermostimulated current (TSC) spectroscopy was applied to the characterization of dielectric relaxations associated with the glass transition of a series of P(VDF/TrFE) copolymers. The maximum temperature of the β‐mode increases slightly as the TrFE unit content is increased, in the same manner as the glass transition temperature. By using the technique of fractional polarizations to the resolution of this relaxation mode, we have isolated, for all the polymers investigated, a series of elementary relaxation times that obey a compensation law. This behavior is characteristic of the free amorphous phase of polymers. The mean activation energy of this mode increases as the TrFE unit content is increased, due to a stiffening of molecular chains. Annealing of the copolymers above their ferroelectric‐to‐paraelectric transition induces a strong crystallinity increase of the materials. As a matter of fact, the amorphous phase is squeezed in to dimensions lower than the characteristic length scale associated with the glass transition. © 1995 John Wiley & Sons, Inc.
PMMA adsorption over previously adsorbed PS studied by polarized FTIR‐ATR
Authors: Enriquez Erwin P. , Schneider Hildegard M. , Granick Steve 
Published: April 2003

AbstractPolarized infrared spectroscopy in attenuated total reflection was used to investigate the adsorption of PMMA (polymethylmethacrylate) onto PS (polystyrene) that was previously adsorbed onto oxidized silicon from dilute solution in carbon tetrachloride at 30°C. The carbonyl group of PMMA forms hydrogen bonds with surface silanol groups, giving segment‐surface interaction energy of 4 kT as against 1 kT for PS (k is the Boltzmann constant, T the absolute temperature). The formation of hydrogen‐bonding by PMMA was unaffected, in rate or amount, by preadsorbed PS, but a lesser total amount of PMMA adsorbed onto PS, resulting in a higher average bound fraction. The histogram of the mass adsorbed, attributable to subpopulations of chains with different bound fractions, was inferred by subtracting infrared spectra acquired at successive times. Whereas this histogram was broad and bimodal for adsorption onto bare surface, it was narrower and unimodal for adsorption onto preadsorbed PS. © 1995 John Wiley & Sons, Inc.
Terbinafine is More Effective Than Itraconazole in Treating Toenail Onychomycosis: Results from a Meta-analysis of Randomized Controlled Trials
Authors: Krob H. Alexander , Fleischer Alan B. , D'Agostino Ralph , Feldman Steven R. 
Published: April 2003

Background: Toenail onychomycosis is a challenge for clinicians to treat, and this challenge is compounded by conflicting information in the medical literature concerning the efficacy of the two principal agents used in its treatment: Terbinafine and itraconazole. Objective: The purpose of this meta-analysis is to compare the efficacy of terbinafine with that of itraconazole in the treatment of toenail onychomycosis caused by dermatophytes. Methods: A Medline search was performed for all English language publications from 1966 to June 1999 on the use of terbinafine and itraconazole in the treatment of toenail onychomycosis. Included were randomized studies in which subjects received no less than 3 months (or cycles) and no more than 4 months (or cycles) of either terbinafine or itraconazole. Data were abstracted and statistical analyses (random effects model, fixed effects model, and Peto's method) were applied. Results: Thirteen studies were included from the original literature review of 1636 total referenced reports; four studies did not fulfill our inclusion or exclusion criteria. The primary analysis of six studies directly comparing terbinafine to itraconazole resulted in an odds ratio ranging from 1.8 (95% CI = 1.8, 2.8) to 2.9 (1.9, 4.1). The secondary analysis of three studies comparing either itraconazole or terbinafine to placebo estimated an odds ratio of 1.1–1.7. The former shows that terbinafine is 80%–190% more likely to result in mycologic cure than is itraconazole; the latter demonstrates a 10%–70% greater likelihood. The difference between the relative efficacies of terbinafine and itraconazole was highly statistically significant ( p < 0.0001). Conclusion: Meta-analysis of the published worldwide literature finds that terbinafine is significantly more effective than itraconazole at achieving mycologic cure of toenail onychomycosis.
Die Anwendung des Wortassoziationstests in der Gedächtnisdiagnostik bei älteren Patienten
Authors: Merten Thomas 
Published: April 2003

Use of the Word Association Technique for Memory Assessment in Older Patients Summary: A free single-word association test (WAT) was performed with 82 older neurological patients (age range: 60 to 85 years), as part of a comprehensive neuropsychological assessment. A list of 25 items was read to the patients twice. First, free associations were obtained and then, response consistency checked immediately. The number of correct repetitions was demonstrated to correlate substantially with other indicators of verbal memory (up to 0.77), such as Wechsler's Logical Memory, Wechsler's Verbal Paired Associates, and verbal learning scores in a selective reminding procedure, but also with rough estimates of cognitive dysfunction such as the Mini-Mental State score (0.59). Total free association response time yielded similarly high correlations with neuropsychological measures, but this was not the case for traditional WAT variables, such as response commonality. The older patients showed a tendency towards preferring paradigmatic associates, such as superordinate, coordinate or synonym responses, in contrast to syntagmatic reactions.
Stationäre Gerontopsychosomatik
Authors: Peters Meinolf , Radebold Hartmut , Hübner Sigrid 
Published: April 2003

Inpatient Gerontopsychosomatics: Investigation of Dosis and Experience of Treatment Summary: With the increase of elderly patients in psychosomatic clinics, the question arises, if the well established concept of treatment works with this group of patients. An empirical study is presented, where 189 elderly patients (> 55 years) and 190 younger patients (< 55 years) are included. They are analysed with different questionnaires, included also the documentation of treatment. The explorative questions were, what about the dosis and utilization of treatment, experience of treatment and valuing of treatment. We find many differences between elderly and younger patients, there are some results of relevance for developing an gerontopsychosomatic concept, wich are discussed.
Topographische Orientierung bei Patienten mit erworbener Hirnschädigung
Authors: Kindsmüller Martina , Kaindl Andrea , Schuri Uwe , Zimmer Alf 
Published: April 2003

Topographical Orientation in Patients with Acquired Brain Damage Abstract: A study was conducted to investigate the abilities of topographical orientation in patients with acquired brain damage. The first study investigates the correlation between wayfinding in a hospital setting and various sensory and cognitive deficits as well as the predictability of navigating performance by specific tests, self-rating of orientation ability and rating by staff. The investigation included 35 neuropsychological patients as well as 9 control subjects. Several variables predicted the wayfinding performance reasonably well: memory tests like the one introduced by Muramoto and a subtest of the Rivermead Behavioral Memory Test, the Map Reading Test and the rating by hospital staff. Patients with hemianopia experienced significant difficulty in the task.