Synergistic Modification Of Poly(Lactic Acid) Multiple Blends By Renewable Elastomer And Flexible Polyester

Poly(lactic acid)(PLA)is one of the most important sustainable polyesters derived from renewable resources.It has good degradability,excellent biocompatibility and high mechanical properties.However,poor impact resistance and flexibility of PLA is still a major hurdle for its diverse applications.Melt blending poly(lactic acid)with soft elastomer is a very cost-effective method to improve its poor properties.In present work,we introduced a third flexible biopolyester into the PLA/ECO blend system to fabricate a series of ternary blends with more balanced performance.The physical properties,miscibility and phase structure were thoroughly studied to establish the relationship between structure and physical performance.1.A series of sustainable polymer blends from renewable poly(lactic acid)(PLA),Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)(P_3,4HB)and Poly(epichlorohydrin-co-ethylene oxide)elastomer(ECO)were fabricated via melt blending method.DMA result showed the adding of P_3,4HB improved the miscibility of the blend.Interplay of composition,mutual miscibility and viscosity ratio of the pristine PLA,P_3,4HB and ECO elastomer resulted in diverse phase structures of the ternary blends.An excellent flexibility at an elongation of 270%was achieved for PLA/P_3,4HB/ECO(70/20/10)blend with a core-shell structure.PLA/P_3,4HB/ECO(70/10/20)blend with a phases-separated structure exhibited a high impact strength of45 k J/m²,which is 25 times over that of the neat PLA.2.Based on previous work and results,more flexible biobased polyesters poly(butylene succinate)and poly(butyleneadipate-co-terephthalate)(PBAT)were selected as the third component for PLA/ECO blend,respectively.DMA and SEM results showed PBS exhibited poor miscibility with PLA,but partial miscibility with ECO.The PLA/PBS/ECO(70/20/10)ratio had the best tensile properties with elongation at break up to 280%,which was 14 times over that of PLA.Yet,the toughenss of the PLA/PBS/ECO was still unsatisfied,which maybe due to the poor impact strength of neat PBS.In contrast,the impact strength of PLA/PBAT/ECO(70/10/20)ternary blend system reached 47.6 k J/m²,which was about 24 times over that of neat PLA.In summary,ternary blend of PLA,ECO and the polyester with different properties(P_3,4HB,PBS and PBAT)is a cost-effective method to achieve PLA based materials with excellent banlanced performance.The mutual miscibility and native physical property of the neat biopolyester(P_3,4HB,PBS and PBAT)play a dominate role in the physical performance of the ternary blends.Selecting a highly tough polyester and improving the interfacial compatibility will be beneficial for enhancing the toughenss of PLA based materials.