VOLUME RELAXATION AND RELATED DYNAMIC MECHANICAL PROPERTY CHANGES DURING PHYSICAL AGING OF POLY-ETHER-ETHER-KETONE (PEEK)

Non-equilibrium glasses, including polymer glasses, spontaneously tend to approach the equilibrium state. The time-dependent phenomena occur ring in glassy polymers below the glass transition are commonly referr ed to as physical aging. Since the physical aging results primarily in a volume relaxation (or densification), our efforts have been focused on the measurements of the time-dependent behavior of the specific vo lume. The dependence of the storage and loss moduli upon aging have be en related to the progressive loss of mobility associated with the vol ume relaxation. A Williams-Watts type equation has been adopted to mod el the volume relaxation data at different temperatures, and a numeric al procedure has been developed in order to predict the kinetics of vo lume relaxation subjected to complex thermal histories.