Abstract
Positron annihilation lifetime spectroscopy (PALS) has been known to be a new analytical method of polymers from the view point of free volume. Positrons injected into polymers form positronium (Ps) after loosing energy through interactions with atoms and molecules. Then migrating in polymers, Ps is trapped in intermolecular spaces and annihilates through pick-off interaction in the spaces. Since the lifetime depends on the size of the holes, the size can be estimated from the lifetime using the experimental equation. Also from the variation of lifetime, glass transition temperature and phase transition at low temperature can be detected. In this paper, characteristics of free volumes measured by PALS are discussed using results of epoxy resins and teflon.
