S. Nishijima et al., STUDY OF EPOXY-RESIN FOR CRYOGENIC USE BY POSITRON-ANNIHILATION METHOD, Journal of radioanalytical and nuclear chemistry, 211(1), 1996, pp. 93-101
The molecular state of epoxy resins for cryogenic use has been studied
in terms of positron lifetime measurement. The addition of plasticize
r increased the free volume in the epoxy and hence the ductility of th
e epoxy at room temperature was increased. The fracture toughness at c
ryogenic temperatures, however, decreased. The increase of molecular w
eight between crosslinks decreased the free volume in the epoxy at roo
m temperature and increased the fracture toughness slightly at cryogen
ic temperature. Based on the data the molecular state model desired fo
r cryogenic application was proposed and the nano-sized silica dispers
ed epoxy was prepared by means of sol-gel method to follow the model.
The cryogenic properties of the silica dispersed epoxy and the free vo
lume evaluated by positron annihilation lifetime were also discussed.