The role of the melting and crystallizing of the stearic acid network in retaining and releasing the mechanical deformation energy during the hot classical shape memory cycle

Abstract

Shape memory natural rubber (SMNR) was prepared using a technique, Elastomer/small molecule blend shape memory polymers (SMPs), by impregnating the commercial natural rubber band (RB) with molten stearic acid (SA) for 2 h and at a temperature of 75 °C, to form commercial natural rubber band RB/based stearic acid (SA) blend SMP, (RB/based SA). Then the success and obstacles indications have been observed in fixing the applied strain of the value of 70% and shape recovery during the hot classical shape memory cycle. This cycle is dependent on the normal cooling at room temperature. That is done by studying the relation of the applied strain with the physico-mechanical phenomena accompanying the activation and deactivation stage of the SME property during this thermo-mechanical cycle. The results of the SME property examination showed that the occurrence of the thermal contraction and elastic retraction is directly responsible for the loss of a part of the elastic applied strain. The value of the applied strain that was restricted is 58.7% instead of 70% after the end of the activation stage, while the plastic strain accumulation was the direct responsibility for the material not being back to its original shape at 100% after the end of the deactivation stage. At the same time, this study shows that the relation of these phenomena to the stretching work energy during the thermo-mechanical cycle is a relationship that falls under the dominance of the first law of thermodynamics and that the shape memory of RB/based SA is only related to the elastic stretching work energy.