Showing papers in "Polymer in 1972"

TL;DR: The Journal Mission Progress in Polymer Science as mentioned in this paper is devoted to the publication of definitive critical reviews of progress in the research area addressed, supported by relevant citations to the published literature, including a majority of citations to literature of the preceding decade.

TL;DR: In this paper, the conditions for propagation of single discontinuities (cracks and crazes) in poly(methyl methacrylate) under the combined influence of stress and solvents were investigated over the range 273K to 323K.

TL;DR: In this article, the birefringence of poly(methyl methacrylate) (PMMA) has been studied for samples deformed plastically in plane strain compression, and the results suggest that the molecular chains are bound by cohesion points which are dissociated by increasing temperature or under the influence of plastic strain.

TL;DR: In this article, high molecular weight poly(N -acryloxysuccinimide) and poly( N -methacrylnoxysccinimides) precursors were obtained by radical polymerization of the corresponding monomers, in turn prepared by coupling of acrylic or methacrylic acid with N -hydroxysuccine in the presence of dicyclohexyl carbodiimide.

TL;DR: In this article, the melting behavior and crystallization mechanisms of linear polyesters have been investigated using X-ray measurements, and the effect of changes of chemical structure on temperature transitions and crystallisation is discussed in detail.

TL;DR: In this article, a new method for assessing crystallinity in cellulosic materials has been established after a rigorous computational analysis of X-ray diffraction traces from the highly crystalline fibrous forms of cellulose I and II, Ramie and Fortisan.

TL;DR: In this paper, a more effective representation of solution, crazing and cracking behavior is obtained by considering the capacity of each liquid to hydrogen bond as well as its solubility parameter.

TL;DR: The brittle point of unnotched specimens occurs when the tensile yield stress is equal to a critical value of tensile breaking stress as mentioned in this paper, which correlates well with the molecular cross-sectional area as calculated from crystallographic data or models.

TL;DR: Differential scanning calorimetry, infra-red absorption and d.c. conductivity were used to study the cure of the system bisphenol-A diglycidyl ether/polyamide in the range 23-110°C as mentioned in this paper.

TL;DR: In this paper, the authors investigated the effect of the secondary mechanical relaxation on the state of cure of amine-cured epoxy resins and showed that the ratio of the values of the shear modulus above and below the transition may be used as a quantitative measure of cure, particularly above the gel point.

TL;DR: The melting behavior of fractions of poly(ethylene oxide) of narrow molecular weight distribution and of molecular weight of 20 000 or less has been studied in this paper, where it is suggested that this increase in σ e is related to an increase in polydispersity of molecular weights in the fractions.

TL;DR: In this article, the fundamental torsional frequencies of methyl groups in poly(propylene oxide) and poly(methyl methacrylate) were calculated for each methyl group in the approximation of a rigid 3-fold rotor attached to an asymmetric frame.

TL;DR: In this paper, a study of low styrene content samples (∼25%) prepared from dilute solution indicated three basic morphologies: an irregular phase structure, arrays of linear and hexagonally-packed circular styrene domains.

TL;DR: In this article, the initial rate constants for the self condensation of halogenophenoxides in anhydrous dimethyl sulphoxide were also determined, and the order of the halogen reactivities was F>CI~Br with p-halogenophenyl sulphonyl groups showing greater reactivity than the o-isomers, while displacement from the m −halogeno sulphones was very slow and comparable with the rate of sulphone bond fission.

TL;DR: In this paper, the state of sorbed water on celluloses derived from cotton and woodpulp sources has been investigated by pulsed nuclear magnetic resonance (n.m.r.) techniques.

TL;DR: In this article, the activation energy for secondary relaxation in amine-cured epoxy resins was measured and the energy was found to be dependent on the degree of cure, increasing from about 14 kcal/mol during the early stages of cure to higher values following post cure after gelation.

TL;DR: The Raman spectra of polyethylene have been analyzed in this article, and it appears that the spectra are sensitive to crystallinity and to the presence of impurities such as vinyl groups.

TL;DR: In this paper, microtomed blocks of acrylonitrileitrile-butadiene-styrene (ABS), high impact poly styrene (HIPS), and highimpact poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) were etched with a mixture of chromic and phosphoric acids, and examined in optical and scanning-electron microscopes.

TL;DR: In this paper, cyclic oligomers were found to be present in poly(1,3-dioxolane) samples prepared by monomer-polymer equilibrations using boron trifluoride diethyl etherate as catalyst.

TL;DR: The reactivity ratios for the free radical copolymerization at 60°C of methacrylonitrile (M1) and styrene have been determined in benzene, benzonitrile, acetonitrile and benzyl alcohol solutions as mentioned in this paper.

TL;DR: The number of active centres in the polymerization system VCl3/AIR3/4-MP-1 has been shown to lie in the range 2·3-6·1 × 10−4mol/mol VCl 3 for a series of aluminium alkyls, and to vary with the nature of the aluminium alyls used as mentioned in this paper.

TL;DR: In this paper, a kinetic scheme for Ziegler-Natta polymerization is proposed, where propagation is considered to occur between adsorbed monomer and an active center which has been formed by interaction of the metal alkyl with the transition metal halide.

TL;DR: The volume-temperature curves of a number of poly(methyl methacrylate) fractions produced by various forms of catalysis have been investigated in this article, and it was confirmed that the isotactic samples have a much lower Tg than has conventional polymer.

TL;DR: In this article, the gel permeation chromatography (g.p.c.) behavior of a wide range of branched polystyrenes, in which the branching frequency and the branch length are varied, is described.

TL;DR: In this paper, the authors examined the Ziegler-Natta system for the polymerization of 4-methylpentene-1 at 30°C and 40°C.

TL;DR: In this article, X-ray diffraction traces of cellulose triacetate fibres heat-treated in the range 220 − 290°C were resolved by a computational method which fits Gaussian or Cauchy functions to the peak profiles.

TL;DR: In this paper, the compatibility of polystyrene/polyisoprene and polybutadiene block copolymers has been investigated using electron microscopy of thin films cast from benzene solutions, showing that all the polymers formed ordered arrays of regular domains.