Positron lifetime spectroscopy characterization of thermal history effects on polycarbonate

A. J. Hill, C. M. Agrawal

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

The effect of a short-term anneal above Tg on the free volume cavity size and concentration and on the fracture toughness of polycarbonate is examined. The positron annihilation lifetime (PAL) technique is used to measure the change in free volume concentration and cavity size during isothermal relaxation experiments at 10, 20 and 30 ° C. An activation energy of 16.5 kJ mol-1 is calculated for the relaxation of the annealed polycarbonate, compared to 12.3 kJ mol-1 for the unannealed material. The fracture toughness and brittle fracture morphology of compact tension specimens are unchanged by the anneal. The similarity in the PAL parameters and physical properties between the unannealed polycarbonate and the material annealed above Tg suggests that the short-term anneal does not appreciably alter the structural state of glassy polycarbonate.

Original languageEnglish (US)
Pages (from-to)5036-5042
Number of pages7
JournalJournal of Materials Science
Volume25
Issue number12
DOIs
StatePublished - Dec 1 1990

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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