Study of the morphology of crosslinked polyethylene and of polymer melts under shear

Peacock, Andrew James (1984) Study of the morphology of crosslinked polyethylene and of polymer melts under shear. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The aim of the work was to study the morphology of various polymers under a variety of conditions. The research followed various lines. The morphology of crosslinked polyethylene and its implications with respect to that of linear polyethylene was studied by Raman spectroscopy, differential scanning calorimetry, electron microscopy, small angle light scattering and nuclear magnetic resonance. The efficiency of the crosslinking reaction was evaluated. The morphology of flowing molten polymers was investigated by Raman spectroscopy. Hot stretched crosslinked polyethylene was studied by vibrational spectroscopy as an aid to investigating the structure of flowing melts. The following results are reported: The morphology, of crosslinked polyethylene is very similar to that of linear polyethylene. This supports Flory's view of the crystallization process. The efficiency of crosslinking polyethylene with dicumyl peroxide is approximately 81.5,1). Orientation of polymer molecules by flow under the wide range of temperatures and shear rates investigated was found to be negligible. Stretching crosslinked polyethylene at temperatures above its crystalline melting point results in preferential extension of a small proportion of polymer chains with little effect on others.

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