Accession Number:

ADA210918

Title:

Hierarchical Structure in Polymeric Solids and Its Influence on Properties

Descriptive Note:

Final rept. Dec 1984-May 1989

Corporate Author:

BRISTOL UNIV (UNITED KINGDOM)

Personal Author(s):

Report Date:

1989-05-01

Pagination or Media Count:

189.0

Abstract:

The work was centered on main chain liquid crystal forming polymers LCP-s such as have potential structural applications as advanced materials. A close ongoing UK-US collaboration has been established where the US workers Prof. Percec, Cleveland are synthetizing tailor made rigid group-flexible spacer polyethers for Physics based examination at Bristol. The varied lines of work and accomplishments are as follows. A broad thermodynamics based scheme was established providing unifying threads through hitherto disconnected phenomena in the LCP field with significant predictive power for ongoing works. Amongst others it encompasses the numerous situation where mesogens are not required for the formation of a liquid crystal LC state. We have been establishing phase diagrams as a function of molecular weight, chemical constitution and copolymer composition. This serves to identify and predict the LC region as a function of the above variables with due distinction between thermodynamic and kinetic factors. In aid of this, a new methodology was introduced simultaneous X-ray diffraction and thermal analysis which was greatly facilitated by synchrotron generated X-rays. The importance of non-equilibrium states was recognized. A separate line of work was on the orientational behaviour of rigid molecules, most of it on the fully rigid rod PBZT. A two-stage relaxational behaviour was identified in semi-dilute entangled solutions by birefringence analysis.

Subject Categories:

  • Physical Chemistry
  • Polymer Chemistry
  • Plastics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE