REJUVENATION AND PHYSICAL AGING OF POLYCARBONATE AT CONSTANT STRAINS IN SIMPLE TENSION AND COMPRESSION.

Abstract

The differential storage modulus E prime was measured intermittently at either 1 Hz or 10 Hz on polycarbonate specimens, each maintained at a different finite strain in either simple tension or compression. Application of such a strain decreases E prime , primarily effected by rejuvenation; thereafter E prime increases progressively, a reflection of physical aging during stress relaxation. Because tensile and compressive strains affect E prime similarly, rejuvenation followed by physical aging cannot be attributed primarily to changes in volume or free volume, as usually defined. Other measurements showed a strong dependence of E double prime on tensile strain and time. The frequency dependence of E prime was also determined at various temperatures during physical aging at a tensile strain of 3%.