Positron annihilation lifetime spectroscopy study on epoxy moisture absorption

Positron annihilation lifetime spectroscopy was used to study the effect of water uptake on the free volume of a commercial epoxy exposed to atmospheres with relative humidity ranging from 30.5% to 95.8%. The absorption process was also analyzed by gravimetric measurements. When exposed to humidity the mean hole volume remains constant and the number of holes not occupied by water molecules decrease with increasing of both the exposure time and the relative humidity as indicated by the constancy of t3 and the decrease of I3