Development of Shape Memory Natural Rubber through prevulcanisation method

Abstract

This article propose a simple method to develop shape memory natural rubber (SMNR) by crosslinking natural rubber latex with fatty acid soap using the prevulcanisation method. By mixing the chemical compounds in the dispersion form, it shorten the fabrication process by reducing the maturation duration. The effect of various crosslink density and fatty acid soap on the SMNR were investigated. To analyse the shape memory behaviours, four types of prevulcanised SMNRs: low crosslink palmitic acid SMNR, high crosslink palmitic acid SMNR, low crosslink stearic acid SMNR and low crosslink pure SMNR were prepared and tested in the strain control mode test under various programming and recovery temperature range. It was found that high crosslink density SMNR exhibit poor shape fixity but possesses shape recovery which is similar to the low crosslink density specimens. It is because crosslink density constrains the growth of strain-induced crystalization during shape programming process. Besides that, the trigger temperature of fatty acid pre-vulcanised SMNR have increased up to their melting temperature of fatty acid. Compared with the shape memory parameters under different temperatures, shape memory effect is highly relying on the temperature of programming process and recovery process.