Showing papers in "Polymer in 1968"

TL;DR: The cross-hatched pattern persists during the growth of polypropylene α-spherulites, and explains their low birefringence as mentioned in this paper, which is different from the radiating lamellar structure of polyethylene and several other polymers.

TL;DR: In this article, three methods, using the Perkin-Elmer DSC-1 isothermally or as a scanning calorimeter, of obtaining isothermal cure curves in terms of heat of reaction versus time are compared and the merits of each method when applied to fast and slow cure rates are given.

TL;DR: In this paper, the physical properties of styrene-butadiene block copolymers are reported for a number of different kinds synthesized by the Living Polymer Technique (LPT).

TL;DR: In this article, the intrinsic viscosities of solutions of fractions of polyethylene terephthalate in o-chlorphenol, dichloracetic acid, phenol-tetrachlorethane and trifluoric acid have been obtained at 25°, 35°, 45° and 55°C.

TL;DR: In this paper, a study was made of the diffusion and solution of helium, hydrogen, neon, argon, krypton, oxygen, nitrogen, methane and carbon dioxide in a series of highly crosslinked copolymer membranes in the temperature range 40° to 80°C.

TL;DR: In this paper, both charge and radical migration mechanisms were considered for the processes whereby reactivity is transferred from the initial alkyl ion to the allyl radical site. And the results indicated that the same mechanisms are operative in both materials.

TL;DR: In this paper, the results obtained from reaction gas chromatography investigations on polyethylene and ethylene-propylene copolymers are discussed with regard to the polymer microstructure.

TL;DR: In this article, an adiabatic, vacuum and a differential scanning calorimeter were used to measure the heat capacity of a 69 per cent crystalline sample of polytetrahydrofuran from 80° to 360°K.

TL;DR: In this paper, the conformational ratios of poly(2,6-dimethyl-phenylene oxide) and poly( 2, 6-diphenyl-phenylon oxide) at 25°C and 90°C in non-ideal solvents are reported.

TL;DR: In this paper, it is suggested that because of the imperfect chain packing in amorphous polymers, intermolecular forces, which fall off rapidly with increasing molecular separation, may not be sufficiently large to account for the observed moduli.

TL;DR: In this article, a method for preparing ultrathin sections through etched ABS surfaces is described, where a layer of resinous black ink is used to identify and protect the surface during sectioning, and the specimen is treated with osmium tetroxide, which stains both the rubbery phase in the ABS and the ink layer.

TL;DR: In this paper, the initial modulus, tensile strength and elongation of linear soluble polyesterurethane fibres were shown to alternate with the number of carbon atoms of the built-in diamines.

TL;DR: In this paper, it has been suggested that the resonance peaks due to backbone protons in helical polymers will be broadened by non-averaging of dipole-dipole interactions and that the areas of these resonance peaks will be a measure of the random coil content of the system.

TL;DR: In this paper, the causes of delamination in thin-walled ABS injection-mouldings were investigated by light and electron microscopy of thin sections, and it was shown that delamination occurs at some depth below the moulded surface, and is due to a layered structure in which the rubber particles are segregated according to size, obliquely deformed, and grouped along the flow lines in rows.

TL;DR: In this paper, alternating block copolymers of polyesters and polyethers have been prepared by end-tipping one of the base units with phosgene, followed by reaction with the second block.

TL;DR: The thermal degradation of poly(benzyl acrylate) at 260° to 300° C has been studied in this paper, where the main products of degradation are carbon dioxide, benzyl alcohol and low polymer.

TL;DR: In this article, a study of the radicals produced during ultra-violet irradiation of methacrylic acid crystals at temperatures below −20°C was made, and it was concluded that reaction is restricted to specific sites in imperfect regions of the crystals in which there is adequate molecular mobility.

TL;DR: In this paper, a value of 0·972 g/cm 3 is advanced as the true density of polyethylene, and a well documented explanation is offered to explain the anomalous high values which can result from pyknometry.

TL;DR: In this article, two series of aliphatic copolyesters have been prepared by ester interchange from four homopolymers, and the melting points, densities, X-ray diffractograms and heats of fusion have been measured.

TL;DR: In this article, annealing of polyethylene single crystals in a temperature range of between 90° and 110°C has been studied by electron microscopy and it was found that each sector begins its transformation at a temperature characteristic for that sector.

TL;DR: In this article, two samples of natural rubber latex have been fractionated by differential solvent extraction of polymer coated glass beads, and molecular weight distributions derived from the experimental data are shown to be bimodal, with peaks at M

TL;DR: In this paper, the use of turbidimetric measurements as a rapid method to characterize molecular-weight distributions of polymers is discussed and an important limitation of the method, not previously reported, is discussed.

TL;DR: The elastic modulus of silicone elastomers is greatly enhanced by the presence of fine particles (fillers) and exposure to high energy radiation offers a convenient method of introducing crosslinks in a quantitative manner as mentioned in this paper.

TL;DR: In this paper, a paracrystalline model for the structure of polypropylene fibres is proposed, and a measured shift in the equatorial diffraction peaks strongly suggest the existence of intermediate states of order.

TL;DR: In this paper, the dielectric properties of PMMA and i-PMMA have been determined over a wide range of temperature and frequency, using the complex plane method to represent the data.