Showing papers in "Polymer in 1991"

TL;DR: In this article, the Young's modulus along the chain axis was calculated for cellulose crystalline forms I and II (native and regenerated celluloses, respectively), and anisotropy of the modulus and linear compressibility in the planes perpendicular to the molecular chain axis were also calculated.

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TL;DR: In this article, bisphenol A-based epoxy resins were modified with either phenolic hydroxyl or aromatic amine functionally-terminated poly(arylene ether sulphone) oligomers and thermally cured with 4,4′ diaminodiphenyl sulphone.

TL;DR: In this paper, the effect of substituents on chain mobility and chain packing has been related to the gas transport properties, and the results for tetramethyl bisphenol A polysulphone (TMPSF), DMPSF, and dimethyl biphenol Z polysULphone (DMPSF-Z) are compared to unsubstituted bisphensol A (PSF).

TL;DR: In this article, the styrene end blocks of a poly(styrene-(ethylene- co-butylene)-styrene) (SEBS) copolymer were sulphonated up to a concentration of 18 mol%.

TL;DR: In this paper, a mixture of nylon 6 with various ABS materials including styrene/acrylonitrile, SAN, matrix component were examined for rheological behaviour, mechanical properties, and phase morphology.

TL;DR: In this article, the effect of viscosity ratio on phase size and size distribution in a co-rotating, intermeshing, twin-screw extruder has been studied.

TL;DR: In this paper, the preparation of conducting polymer-colloidal silica composites by the in situ deposition of a thin coating of chemically synthesized polyaniline or polypyrrole onto monodisperse silica particles (∼ 1 μm diameter) is described.

TL;DR: In this paper, the authors used light and small-angle neutron scattering techniques to evaluate the molecular parameters of protein chains (radius of gyration, persistence length, cross-section, mass per unit length) and determine the quality of the solvent (0.1 M NaCl solutions in H2O or D2O at pH = 7).

TL;DR: In this paper, a set of polypropylene (PP) fractions with similar molecular masses and distributions but different isotacticities have been studied through wide-angle X-ray diffraction, small-angle x-ray scattering and differential scanning calorimetry measurements.

TL;DR: In this article, the structural relationship between α and γ phases makes it possible to determine the left or right-handed chirality of all helices in the single crystals.

TL;DR: A segmented rigid-rod polyimide has been synthesized from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 2,2′-bis(trifluoromethyl)-4, 4′-diaminobiphenyl (PFMB) as discussed by the authors.

TL;DR: In this article, a compatible blend of an inorganic polymer, silica glass, and a π-conjugated non-linear optical polymer, poly(p -phenylene vinylene), homogeneously miscible over wide composition ranges, was reported.

TL;DR: In this article, the influence of composition and thermal history on the phase structure and crystallization processes of poly( d (−)-3-hydroxybutyrate) (PHB) and poly(ethylene oxide) (PEO) blends at temperatures below the melting temperature of PHB has been investigated by differential scanning calorimetry and scanning electron microscopy.

TL;DR: In this paper, the molecular weight distribution of poly(aryl ether ether ketone) (PEEK) has been measured as a function of the melt holding temperature and time in air and in an inert environment.

TL;DR: The lower limit for the activation energies of internal motions in polymers is defined by a relationship corresponding to anactivation entropy of zero, and local-mode γ relaxations of the main chain appear to involve a spectrum of motions in which the limiting low-temperature, high-frequency component has an activation entropy close to zero.

TL;DR: In this article, a copolymerization process utilizing the difference of the monomer reactivities was used to control the refractive-index profile and the light scattering of such graded index materials.

TL;DR: In this article, the properties of isotactic polypropylene (PP) blended with different amounts of ethylene-propylene-diene (EPDM) terpolymer were investigated.

TL;DR: In this paper, a linear dependence of the glass transition temperature of the isotropic materials on composition was obtained, and the PET/PEN/PHB ternary copolyester containing equal parts of each of the three components can be obtained at room temperature as a liquid-crystalline glass and as an isotropically glass, depending on thermal history.

TL;DR: In this article, a series of tough thermosetting resins based on the incorporation of amine-terminated poly(aryl ether ketone) oligomeric derivatives into commercial epoxy/amine resins, through a solventless process, have been evaluated.

TL;DR: In this article, the phase separation of pure hard-block polyurethanes and amorphous segmented hydrogenated polybutadiene (H.PBD) was analyzed using dielectric measurements.

TL;DR: Ionomers prepared from a sulphonated poly(styrene-(ethylene-co-butylene)-styrene) triblock copolymer possessed a unique three-phase microstructure that consisted of 3-4 nm ionic domains within 20-30 nm polystyrene domains dispersed in a rubbery continuous phase as mentioned in this paper.

TL;DR: In this paper, the authors investigated the thermal properties of oriented polymer networks obtained by photopolymerization of liquid crystalline acrylates and found that the tensile modulus and the strength of the oriented networks were anisotropic and highly temperature dependent.

TL;DR: In this paper, the gas sorption and transport properties of a series of polysulphones in which the isopropylidene unit of bisphenol A polypolysulphone (PSF) has been replaced with another molecular group are reported.

TL;DR: In this article, it was shown that the phase separation that occurs on heating above the glass transition is not a result of a lower critical solution temperature (LCST) just above Tg but stems from an extremely slow rate of phase separation from the trapped nonequilibrium state.

TL;DR: In this paper, the influence of EPR molecular structure and composition on the melt rheology, on the mode and state of dispersion of the minor component in the melt as well as in the solid state and on the impact properties of injection-moulded samples was investigated.

TL;DR: In this paper, X-ray diffraction patterns of the drawn PDMPV fibres indicated a high degree of molecular orientation with a mosaic spread less than 8°, and a strong correlation between the electrical conductivity and the mechanical properties was found.

TL;DR: The facts that t∗ is independent of the magnitude of the strain and that the volume recovery after a quench remains unaltered, in spite of the imposition of mechanical deformations, support the argument that mechanical stimuli neither alter the underlying (non-equilibrium) thermodynamic state of the glass nor erase physical ageing.

TL;DR: In this paper, the Cahn-Hillard theory was used to predict phase separation in one mixture of poly(ethylene oxide) and poly(ether sulphone) (PES/PEO).

TL;DR: In this article, surface modification of poly(tetrafluoroethylene) (PTFE) samples were surface modified in gas plasma atmospheres of air, oxygen, argon and water vapour in order to increase the surface energy.