Activation Energy Spectra for Relaxation in Amorphous Materials. I. Volume Relaxation in Polystyrene and Polyvinyl Acetate

Abstract

A modification of the Primak analysis for activation energy distributions is presented and compared with the well‐known analysis for relaxation time distributions. Mathematical and physical interrelationships between the two analyses are discussed. Activation energy spectra are derived from the data of Kovacs for volume relaxation in polystyrene and polyvinyl acetate. The energy spectra are bell shaped and cover the range from 5 to 20 kcal/mole. The concept of a shift factor is introduced to account for changing structure in the glass transition region. The shapes and locations of the spectra are discussed and compared with previous interpretations of volume relaxation data.