POSITRON-ANNIHILATION SPECTROSCOPY FOR CHEMICAL-ANALYSIS - A NOVEL PROBE FOR MICROSTRUCTURAL ANALYSIS OF POLYMERS

Positron annihilation spectroscopy for chemical analysis (PASCA) has been developed to analyze the microstructure of polymers. Positron annihilation lifetime measurements give direct information about the dimension and contents of free-volume holes in amorphous materials. The angular correlation measurements of positron annihilation radiation give additional information about the shape of the free-volume holes in oriented polymeric materials. The unique capability of PASCA to probe free-volume properties is from the fact that positronium atom is trapped in the atomic-scale holes which have a size ranging from 1 to 10 Å. Theoretical aspects, experimental developments of PASCA, and examples in analyzing the microstructures of epoxy, PEEK, and PMMA polymers are presented. © 1990.