Solid-state foaming of epoxy resin under hypergravity and simulated microgravity

Abstract

Solid-state foaming of epoxy resins has been performed under simulated microgravity by the random positioning machine (RPM) and under hypergravity by the large diameter centrifuge (LDC). More than 50 tests have been performed in static and dynamic conditions in different experimental configurations. Longitudinal, radial, and volumetric foaming ratios have been extracted from foaming tests, and correlated with the applied gravity conditions. Results show that the gravity vector has two opposite effects; the first on the flow front movement and the second on the contact between the sample and the oven. The second effect seems to be stronger, and the important role of heat transfer is confirmed. Nevertheless, effects related to apply centrifugal forces have been found and discussed, above all in the case of LDC tests.