Positron lifetime spectroscopy characterization of thermal history effects on polycarbonate

A. J. Hill; C. M. Agrawal

doi:10.1007/BF00580127

Positron lifetime spectroscopy characterization of thermal history effects on polycarbonate

A. J. Hill, C. M. Agrawal

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Abstract

The effect of a short-term anneal above T_g 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 T_g suggests that the short-term anneal does not appreciably alter the structural state of glassy polycarbonate.

Original language	English (US)
Pages (from-to)	5036-5042
Number of pages	7
Journal	Journal of Materials Science
Volume	25
Issue number	12
DOIs	https://doi.org/10.1007/BF00580127
State	Published - Dec 1 1990

ASJC Scopus subject areas

Materials Science(all)
Mechanics of Materials
Mechanical Engineering

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10.1007/BF00580127

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Hill, A. J., & Agrawal, C. M. (1990). Positron lifetime spectroscopy characterization of thermal history effects on polycarbonate. Journal of Materials Science, 25(12), 5036-5042. https://doi.org/10.1007/BF00580127

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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.",

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