Showing papers in "Polymer in 1993"

TL;DR: In this paper, the authors studied the optical absorption change of polyaniline at various levels of oxidation and protonation, and the evolution of band structure corresponding to the optical-absorption change during each specific oxidation state is studied by gradually changing the acid strength of the solution to which the polymer is subjected.

TL;DR: An epoxy based on the diglycidyl ether of bisphenol A (DGEBA) has been modified with poly(phenylene oxide) (PPO) and cured with piperidine as discussed by the authors.

TL;DR: In this paper, the room temperature crystal structures, unit cell dimensions at 110K and phase transitions of three poly(p-phenylene) oligomers are reported, and the results of a molecular mechanics study on the conformation and packing of PSP are also presented.

TL;DR: The crystal structure of polystyrene-toluene molecular compound was studied by X-ray diffraction as discussed by the authors, and the crystal data are as follows: monoclinic system, space group P21/a (no. 14), a = 17.58, b = 13.26, c(chain axis) = 7.71 A, γ = 121.2 °, eight monomer units (two chains) and two toluene molecules per unit cell, the molar ratio of monomer: tofluene being 4:1.

TL;DR: A filled epoxy resin used as a structural adhesive and based on the diglycidyl ether of bisphenol A cured with dicyandiamide has been subjected, in its bulk form, to ageing at 40, 55 and 70°C and ca. 100% relative humidity as discussed by the authors.

TL;DR: In this paper, the miscibility of copolymer compositions has been studied by a film clarity test, Tg and cloud-point (Tp) studies, and the phase diagrams of the blends were determined.

TL;DR: In this paper, a simple annealing treatment was proposed to rejuvenate poly(R)-3-hydroxybutyrate (PHB) while preventing subsequent aging. But the results showed that PHB can be rejuvenated while subsequent ageing is prevented to a large extent, which might enlarge the applicability of PHB.

TL;DR: In this paper, the diffusion of small molecules in polymers was measured using Fourier transform infra-red-attenuated total reflection (FTi.t.r) spectroscopy, which allows one to study liquid diffusion in thin polymer films in situ.

TL;DR: In this paper, Fourier transform infra-red (FTi.r.) spectroscopy was used for real-time monitoring of the molecular changes occurring during the thermo-oxidative degradation of polybenzimidazole material.

TL;DR: In this article, the swelling properties of perfluorosulphonated ionomer (PFSI) membranes have been studied as a function of the solvent, the counterion and the temperature.

TL;DR: In this article, the microstructural state of glassy polymers that evolve during physical ageing and inelastic deformation was studied, showing that ageing is accompanied by enthalpy relaxation.

TL;DR: In this paper, the effect of surface treatment on cell adhesion using polyethylene, polytetrafluoroethylene (PFL), poly(ethylene terephthalate), polystyrene, and polypropylene films was studied.

TL;DR: In this paper, a micromechanically based composite model is employed to study large plastic deformation and texture evolution in initially isotropic high density polyethylene (HDPE) under different modes of straining.

TL;DR: In this paper, it was shown that plots of log G′ versus log G″ have a basis of molecular viscoelasticity theory and thus the two are not related to each other.

TL;DR: In this paper, absorbable fibres have been prepared from various copolymers of l -lactide with either d -latide or ϵ-caprolactone.

TL;DR: In this paper, a comprehensive study of the parameters affecting the degradation of polymers under irradiation with high-intensity ultrasound was performed, which demonstrated that the limiting molecular weight and polydispersity of the materials can be controlled by suitable manipulation of the experimental conditions.

TL;DR: In this article, the existence of a liquid-crystalline phase implies a rather rigid conformation of the fully protonated polyaniline in solution, and it is suggested that protonation induces a chain stiffening and extension of the macromolecules resulting from a combination of electronic delocalization and counter-ion "crowding".

TL;DR: In this paper, the crystal structure of the iodine molecular compound with uniaxial orientation was obtained by immersing amorphous polystyrene (obtained by quenching the melt into ice-water followed by stretching) into molten iodine at 120-130°C.

TL;DR: In this paper, the average lamellar thickness lC was calculated as the product of LMC and xCL during crystallization at temperatures of 230-310°C, and the bulk degree of crystallinity (by weight), ψC, was determined by WAXD.

TL;DR: The crystal structure of a planar zigzag form of syndiotactic polystyrene (planar form I) obtained by annealing as-cast samples from solutions (molecular compounds with the solvents) was studied by X-rays as discussed by the authors.

TL;DR: In this article, the glass transition as a function of water content was studied using d.m.t.a., pulsed n.r.s.c., and a three-point bend test.

TL;DR: In this article, the authors showed that poly(vinyl alcohol) copolymers with H3PO4 can be flame retardant to a certain extent by phosphonylation, and that the flame retardance arises in part from a condensed-phase mechanism involving dehydration, crosslinking and intumescent char formation.

TL;DR: In this article, the effects of blending time, temperature, blend composition and polyester catalyst on transesterification were determined using nuclear magnetic resonance, and rate constants and an activation energy for the process were determined.

TL;DR: In this paper, the effect of compatibilization of blends of polypropylene (PP) with a thermotropic liquid-crystalline polymer (LCP) was considered in an attempt to improve the mechanical properties obtained by blending alone.

TL;DR: In this article, columnar mesophases with hexagonal symmetry observed in polymers as flexible as polyethylene and poly(diethylsiloxane) are columnar liquid crystal.

TL;DR: In this article, the authors describe a preparative and an analytical temperature-rising elution fractionation (t.r.f) technique as the primary tools to separate and characterize a commercial impact copolymer.

TL;DR: In this paper, a new imide-containing phthalonitrile resin was synthesized and studied by thermal analysis, which is readily converted into the imide linkages before commencing with the polymerization reaction.

TL;DR: Grafting of maleic anhydride (MAH) onto isotactic polypropylene (PP) was performed by melt mixing in a laboratory-scale internal mixer with the addition of dicumyl peroxide (DCP) as an initiator.

TL;DR: In this paper, a pendent group of poly( N -isopropylacrylamide) was incorporated into pendent groups to obtain chemical-responsive polymer systems and the aqueous solution of the polymer containing 11.6 mol% pendent benzo[18]crown-6 groups underwent a phase transition from the phase-separated to the homogeneous state at 32°C by the addition of K + and Na +.

TL;DR: In this article, the effects of morphology on the fracture toughness of modified epoxy resins were investigated and the co-continuous structure and morphology of the PEI spherical domain dispersed in the epoxy matrix were obtained.