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It is shown that the incorporation of interleaved films has major advantages for the production of polyethylene single polymer composites by the process of selective melting (termed hot compaction). The key issue is to choose a compaction temperature which melts the minimum amount of the original oriented elements whilst achieving acceptable bonding within the compacted structure. Utilising an interleaved...
In this paper, the results of using a mass spectrometer technique to measure mixed-gas diffusion through polymer films are presented. Mixtures of oxygen, carbon dioxide and nitrogen are diffused through films of polyethylene with different degrees and type of chain branching. It is shown that in the case of pure gases Henry's law applies; the gas concentration is proportional to the partial pressure...
The development of morphology in tapes and woven cloths of oriented melt-spun Tensylon polyethylene has been studied both before and after hot compaction over a range of temperatures below and above the optimum. For both the unidirectional fibres and the woven cloths, the optimum temperature was found to be where approximately 30% of the original structure was lost which, for Tensylon tapes, was ~2K...
Specimens of the polyethylene Sclair 2907, full of large banded spherulites, have been drawn to high extensions, and parts of these annealed close to their melting points under constraint. Etching with permanganic reagents and examination under the scanning electron microscope revealed that in transverse sections of the unannealed specimens, the legacy of the banded spherulitic morphology is seen...
Morphological investigations on a range of polyethylenes, which differ with respect to their molecular weight characteristics and which possess quite distinctly different superstructures, non-spherulitic and banded spherulitic, have been performed to follow structural developments during drawing. Of particular significance is the detailed examination of transverse sections, in addition to the more...
The yield strain has been measured over a wide range of temperatures for four polyethylene grades which differ with respect to both their short chain branch content and their molecular weight. The results have shown that all the materials exhibit a transition in their mechanical behaviour at sub-ambient temperatures. The transition temperature is shown to increase as the crystallinity is increased...
The effects of crystallinity, lamellar thickness and stem length on the yield behaviour of a range of bulk crystallized and pressure annealed polyethylenes have been analysed. The materials studied differ greatly with respect to lamellar thickness, stem length and the degree of crystallinity. Measurements of the yield stress were carried out at −60°C and at a strain rate of 3.5×10−3s−1, where the...
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