PHYSICAL-PROPERTIES OF EPOXY AND FREE-VOLUME EVALUATED BY POSITRON-ANNIHILATION SPECTROSCOPY

The macroscopic physical properties of commercially available bispheno l -A epoxy resins cured by acid anhydride in which amount of the plast icizer, polypropyleneglycol was changed systematically have been measu red and were compared with the amount of free volume evaluated by the positron annihilation technique. The lifetime and the intensity of ort hopositronium were used to evaluate the amount of the free volume in t he epoxy resins. It was found that up to the certain amount of plastic izer, the amount of the free volume did not increase so much and then showed the marked increase. The close correlations were found between the amount of the free volume and the macroscopic physical properties such as hardness and specific volume.