Thesis-1976-Moneypenny.pdf (8.13 MB)
Download file

The influence of pressure on relaxations in glassy-state polymers

Download (8.13 MB)
thesis
posted on 21.11.2018, 11:39 authored by Henry G. Moneypenny
Glass-forming high polymers have been densified by application of high hydrostatic pressure (≈ 1.5 kbar) in the melt, followed by cooling under pressure to ambient. A density increase of about 1% was induced in each of the following polymers: polyvinyl chloride, polymethyl methacrylate, polystyrene, poly-4-chlorostyrene, poly-3-chlorostyrene, poly-4-methoxystyrene and poly-4-phenoxystyrene. Differential thermal analysis (DSC) and volume relaxation techniques were used to study the reversion of the densified glass to a more normal glass at a temperature ≈Tg–15K in general. Enthalpy relaxation (a change from glass I to glass II) in this region gives a peak or diffuse hump on the DSC scan prior to a normal glass transition temperature. It is considered that although the densified glasses may become thermodynamically stable at a sufficiently low temperature they are inherently unstable at ambient. Reversion to a more normal class is kinetically too slow to measure at ambient in all cases studied except polymethyl methacrylate. [Continues.]

Funding

Science Research Council (research scholarship).

History

School

  • Science

Department

  • Chemistry

Publisher

© H.G. Moneypenny

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

1976

Notes

A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy at Loughborough University.

Language

en

Usage metrics

Keywords

Exports