MEASUREMENT OF HOLE VOLUME IN AMORPHOUS POLYMERS USING POSITRON SPECTROSCOPY

Positron annihilation lifetime spectroscopy (PALS) measurements, in th e temperature range 110-480 K, are given for three linear, amorphous p olymers. Based on these measurements, a method is proposed for evaluat ing the hole volume in amorphous thermoplastics. Our studies show that hole volume is composed of static and dynamic components. We demonstr ate that the dynamic component, which is a result of the thermal vibra tions of the molecular chains, is strongly correlated to thermodynamic volume/density fluctuations, The static hole volume is interpreted as ''frozen-in'' fluctuations, which are manifested as nanometer-sized f laws in the packing of molecular chains. The results from PALS measure ments reported in our work are in very good agreement with results fro m small-angle X-ray scattering measurements.