Linear thermal expansivity (1.5–300 K) and heat capacity (1.2–90 K) of Stycast 2850FT

Abstract

Linear thermal expansivities, α, have been obtained from 1 to 300 K for a sample of Stycast 2850FT epoxy that initially was cured at room temperature (X1), and then at 95 °C (X2). Heat capacities, Cp, were measured from 1 to 95 K for X2. The α’s for X1 and X2 are roughly equal to and twice that of copper near room temperature, but differ by as much as 10% at low temperature. The α’s approach those for copper near 100 K, but have a much smaller temperature dependence at lower temperatures. The different shapes of the α(T) and Cp(T) relations give a Grüneisen parameter, Γ, which decreases from 1.2 at 10 K to 0.5 at 95 K. Both α and Cp show apparent changes in lattice properties near 4.5 K, and a low temperature anomaly (Γ=3.5) that is characteristic of amorphous solids. Sample relaxation (shortening) effects from 300 K to 110 K were more serious for X2 than for X1. Because of differences related to the curing procedure, these data should be used only semiquantitatively in the design of experiments in which Stycast 2850FT will be used as a construction material. Possible Stycast-related problems with a capacitance dilatometer are discussed.