Thermo‐responsive shape memory properties based on polylactic acid and styrene‐butadiene‐styrene block copolymer

This study aims to compare thermal, mechanical, and shape memory behavior of polylactic acid (PLA) blended with different structures of styrene‐butadiene‐styrene block copolymer (SBS), namely linear SBS (L‐SBS), and radial SBS (R‐SBS). The amount of L‐SBS and R‐SBS added was varied between 10 and 70 wt%, and the blending process was carried out using an internal mixer at 180°C before the shaping process by the compression molding. An improvement in the degree of crystallinity was observed across the entire composition range with less pronounced transition temperature change. Tensile strength and modulus of PLA/L‐SBS blends were higher than PLA/R‐SBS blends across all composition ranges. The results also revealed that the shape fixing ratio (Rf) and recovery ratio (Rr) of PLA/L‐SBS were higher than PLA/R‐SBS, with PLA70/SBS30 showed the best shape memory behavior. The morphology characteristics of the blend were also examined with the scanning electron microscope. This paper examines the shape memory behavior of polylactic acid in the presence of different amounts of linear or radial styrene‐butadiene‐styrene (SBS) block copolymer upon exposure to heat stimuli. At fixed compositions, blend with linear SBS indicated a higher shape fixity ratio and shape recovery ratio compared with radial SBS even at different deformation temperatures.