Entropy and fragility in chain polymers and the ΔC p problem

Charles Angell

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The fragility of glassforming systems, which is correlated strongly to the magnitude of aging effects below T g, is related to the rate per K at which the liquid (or rubber) is approaching its configurational ground state, i.e. the rate at which its excess (non-vibrational) entropy is 'running out'. For simple liquids, it is usually correlated to the increase of C p normalized to the glass value at T g. The most fragile glassformers identified to date have been chain polymer, PVC being the extreme case (for structural reasons which are far from clear). For chain polymers, however, the change of heat capacity at T g relative to the glass value of T g is small, approx.10% compared to approx.80% for fragile molecular liquids. We examine the origin of this difference and discuss its relevance to the vibrational dynamics of amorphous systems.

Original languageEnglish (US)
Title of host publicationPolymeric Materials Science and Engineering, Proceedings of the ACS Division of Polymeric Materials Science and Engineering
Editors Anon
PublisherACS
Pages208
Number of pages1
Volume76
StatePublished - 1997
EventProceedings of the 1997 Spring ACS Meeting - San Francisco, CA, USA
Duration: Apr 13 1997Apr 17 1997

Other

OtherProceedings of the 1997 Spring ACS Meeting
CitySan Francisco, CA, USA
Period4/13/974/17/97

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Polymers and Plastics

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