Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Energy, Environment Protection, Nuclear Power Engineering
Abstract The molecular state of epoxy resins for cryogenic use has been studied in terms of positron lifetime measurement. The addition of plasticizer increased the free volume in the epoxy and hence the ductility of the epoxy at room temperature was increased. The fracture toughness at cryogenic temperatures, however, decreased. The increase of molecular weight between crosslinks decreased the free volume in the epoxy at room temperature and increased the fracture toughness slightly at cryogenic temperature. Based on the data the molecular state model desired for cryogenic application was proposed and the nano-sized silica dispersed epoxy was prepared by means of sol-gel method to follow the model. The cryogenic properties of the silica dispersed epoxy and the free volume evaluated by positron annihilation lifetime were also discussed.
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