ELASTOMERIC SEALS AND MATERIALS AT CRYOGENIC TEMPERATURES. PART 2

This research deals with low temperature investigations of elastomeric polymers, with particular emphasis on their use as seals at cryogenic temperatures. The present report starts with a brief review of elastomeric O-rings used as crush gaskets, followed by new work on elastomer-indium combination seals and various O-ring coatings. Pressure actuated seals are then examined in some detail, both analytically and experimentally. Several new designs which combine pressure actuating metal bodies with elastomeric or other sealing surfaces are described, and experimental results are given. A brief study of the behavior of thin elastomeric membranes at cryogenic temperatures was made with a view to their possible use for expulsion bladder construction. Studies of elastomer properties include a look at creep of highly compressed O-rings over 15-day periods, the effects of fillers and chain orientation on thermal expansion rates, and differential thermal analysis as a tool for study of low temperature transitions. The automatic ball rebound apparatus has been further refined, and will be used for a detailed study of damping at high frequencies and at temperatures from approximately 100 K to 100 C.