Rheological and thermoresponsive shape memory properties of polylactic acid (PLA) and styrene-butadiene-styrene (SBS) copolymer blends

In this study, a thermoresponsive shape memory polymer based on various compositions of melt blended of polylactic acid (PLA) and styrene-butadiene-styrene (SBS) copolymer was prepared. Dynamic rheological behavior was measured using a parallel plate rheometer over a range of 0.1-100 rad(- 1) and was correlated with the shape memory, thermal and tensile properties of the blends. The blend with 70%PLA (70PLA/30SBS) that possessed intermediate storage and loss moduli showed the best shape memory performance in terms of shape fixity ratio (R-f) and shape recovery ratio (R-r). The tensile strength and modulus increased while elongation at break reduced with increasing PLA with significant changes found at 50PLA/50SBS due to the formation of co-continuous morphology. The SBS content did not significantly affect the glass transition temperature of the PLA but the crystallinity slightly increased with increasing SBS. The sea-island morphology of 70PLA/30SBS where SBS formed droplets in the PLA continuous phase provides optimum tensile and shape memory properties.

Automated summary

In this study, a thermoresponsive shape memory polymer based on melt blended compositions of polylactic acid (PLA) and styrene-butadiene-styrene (SBS) copolymer was prepared. The blend with 70%PLA (70PLA/30SBS) showed the best shape memory performance in terms of shape fixity ratio and shape recovery ratio. The tensile strength and modulus increased while elongation at break reduced with increasing PLA content, with significant changes found at 50PLA/50SBS due to the formation of co-continuous morphology. SBS content did not significantly affect the glass transition temperature of PLA but increased its crystallinity slightly. The sea-island morphology of 70PLA/30SBS provided optimal tensile and shape memory properties.