FREE VOLUME AND CRYOGENIC PROPERTIES OF HYBRID MATERIALS

摘要

Cryogenic characteristics of hybrid materials, which consist of epoxy and nanosize ceramic filler such as silica, have been studied in order to control the crosslinking density or the free volume size of polymeric materials. The positron annihilation lifetime (PAL), by which the free volume size of polymeric materials can be evaluated, was measured and the relationship between positron lifetime and cryogenic properties such as fracture toughness or thermal contraction, were investigated down to cryogenic temperatures. It was found that cryogenic properties of hybrid material depend on PAL and free volume size. As an attempt to understand the microscopic state, molecular dynamics simulations were carried out. It also suggested that molecular design of hybrid material was suitable to obtain better cryogenic properties.