Effectiveness of starch nanocrystals on mechanical and shape memory behaviour of smart rubber

Shape memory rubber (SMR) is a type of smart rubber that can undergo reversible changes when exposed to external stimuli such as temperature, solvent, pH, light, magnetic field and oxidation. Lightly crosslinked rubber demonstrated shape memory behaviour without any initial heat treatment. However, the strength of lightly crosslinked natural rubber latex (NRL) film cured by sulphur is relatively low. With the concept of sustainability in mind, the idea of fabricating green smart material for continuous development has motivated researchers to explore the realms of sustainable materials. This research aims to investigate the mechanical behaviour of starch nanocrystals (SNC) reinforced rubber composite films. To this end, the emphasis is laid on evaluating the effectiveness of SNC on shape memory effect (SME) of rubber nanocomposite films. In the current work, up to 8 wt% of SNC synthesized by acid hydrolysis was incorporated into NRL and the mixture was cast to form rubber nanocomposite films. SNC effectively increased the modulus and energy-storing potential of the rubber nanocomposite films. Moreover, the shape memory behaviour of the rubber nanocomposite films improved significantly with SNC content, leading to increased shape fixity (Sf) and full shape recovery (Sr).