Tailoring toughness of fully biobased poly(lactic acid)/natural rubber blends through dynamic vulcanization

Direct blending of poly(lactic acid) (PLA) with elastic natural rubber (NR) could not generate highly toughened blend, due to immiscibility between PLA and NR. In this study, we improved the compatibility of PLA/NR blend by dicumyl peroxide (DCP) initiated dynamic vulcanization and systemically investigated the effect DCP content on the morphology and mechanical properties of the resulting fully biobased PLA/NR blends. Both the pristine PLA/NR and dynamically vulcanized PLA/NR blends showed phase-separated morphology with dispersive NR particles dispersed in the PLA matrix. The particle size of NR decreased, the interfacial adhesion between the components increased, and the toughness of the sample first increased and then decreased with increase in the DCP content. When the DCP content was 3 wt%, the blend showed the highest toughening efficiency with impact strength and elongation at break of 220.2 J/m and 42.1%, respectively, which were 305% and 859% higher than those of pristine PLA/NR blend with the values of 72.1 J/m and 4.9%, respectively. The tensile strength and Young's modulus of the dynamically vulcanized samples were comparable to those of the pristine PLA/NR blend.