Investigation of inelastic behavior of elastomeric composites during loading–unloading cycles

Abstract

The inelastic responses of thermoplastic polyurethane/attapulgite (AT) elastomeric composites were studied by an elastic-testing machine combining with an infrared camera during loading–unloading cycles, in which the former detected the mechanical properties while the latter reflected the thermal effects of deformation. For both unfilled and filled polyurethanes, some significant inelastic features were noticed that in the first cycle hysteresis and most stress softening occurred, and the corresponding temperature variation was partly reversible. However, in the following cycles, the specimen approached a steady state, therefore, stress–strain curve and the corresponding temperature variation was totally reversible. It was also showed that in filled materials the inelastic effects were becoming more obvious with the increase of AT concentration. The results can be explained by chain slippage of the hard micro-domain existing in soft segments of polyurethane, which produces irreversible friction dissipation during the initial loading process.