| Abstract: | Positron annihilation spectroscopy has been used to study free volume in an arnine-cured epoxy as a function of external pressure at temperatures above and below the glass transition temperature. The observed ortho-positronium lifetime τ3 and formation probability I3 decreased with increasing pressure. The decrease in τ3 is interpreted in terms of a corresponding decrease in average free-volume hole size over the range from 0.135 to 0.045 nm3. The fractional free-volume and the free-volume compressibility in the epoxy are calculated as functions of pressure at 100°C. |
