LINEAR THERMAL EXPANSIVITY (1.5-300 K) AND HEAT-CAPACITY (1.2-90 K) OF STYCAST-2850FT

Linear thermal expansivities, alpha, have been obtained from 1 to 300 K for a sample of Stycast 2850FT epoxy that initially was cured at roo m temperature (X1), and then at 95 degrees C (X2). Heat capacities, C- p, were measured from 1 to 95 K for X2. The alpha's for X1 and X2 are roughly equal to and twice that of copper near room temperature, but d iffer by as much as 10% at low temperature. The alpha's approach those for copper near 100 K, but have a much smaller temperature dependence at lower temperatures. The different shapes of the alpha(T) and C-p(T ) relations give a Gruneisen parameter, Gamma, which decreases from 1. 2 at 10 K to 0.5 at 95 K. Both alpha and C-p show apparent changes in lattice properties near 4.5 K, and a low temperature anomaly (Gamma = 3.5) that is characteristic of amorphous solids. Sample relaxation (sh ortening) effects from 300 K to 110 K were more serious for X2 than fo r X1. Because of differences related to the curing procedure? these da ta should be used only semiquantitatively in the design of experiments in which Stycast 2850FT will be used as a construction material. Poss ible Stycast-related problems with a capacitance dilatometer are discu ssed. (C) 1997 American Institute of Physics.