The Effect of Palmitic Acid Loadings on the Shape Memory Cycle of Shape Memory Natural Rubber

Abstract

This article investigates the effect of palmitic acid loadings on the shape memory cycle testing of shape memory natural rubber (SMNR) fabricated via prevulcanisation method. By incorporating the palmitic acid, the strain-induce crystal (SIC) formation between the SMNR molecules possess the ability of demonstating the shape memory effect (SME) above the room tempeature. To analyse the SIC formation on prevulcanised SMNR, the shape memory cycling tests were investigated as a function of palmatic acid loadings under strain control mode. From the observation of TGA results, various palmitic acid contents of SMNR were fabricated under prevulcanisation method but the palmitic acid loading is different from the palmitic acid amount used in the mixing process. Furthermore, it was also found that shape fixity of the SMNR developed can be improved by increasing the palmitic acid loadings but the shape fixity results starts to decline with increasing number of shape memory cycle due to the bleeding of palmatic acid. It indicates that the palmitic acid content has signficant influence on the SIC formation. On the other hand,the specimens still remain the elastic property which reform back to orginal length upon recovery process even after repeatative shape memory test. It is believed that the material properties of SMNR still were dominated by the natural rubber network during the recovery process.