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Isothermal volume relaxation in aged polycarbonate measured by positron annihilation lifetime spectroscopy
Author(s) -
Hill A. J.,
Katz M.,
Jones P. L.
Publication year - 1990
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760301303
Subject(s) - polycarbonate , materials science , relaxation (psychology) , isothermal process , activation energy , volume (thermodynamics) , spectroscopy , positron lifetime spectroscopy , positron annihilation , positron , annihilation , nuclear magnetic resonance , analytical chemistry (journal) , thermodynamics , composite material , chemistry , organic chemistry , electron , nuclear physics , medicine , physics , quantum mechanics
The positron annihilation lifetime spectroscopy (PALS) technique is used to measure volume relaxation in physically aged glassy polycarbonate. The relaxation times and activation energy calculated for the isothermal relaxations in the aged polycarbonate are greater than those parameters calculated for unaged polycarbonate. The activation energy of 8.2 kcal/mol in the aged polycarbonate is used to identify the phenyl group motion or the cooperative carbonate‐phenyl interaction as the molecular features responsible for the thermally induced open volume relaxations. It is postulated that the open volume relaxation kinetics as measured by PALS can be used as a nondestructive indication of property differences between aged and unaged polycarbonate.