Bio-based polyamide-assisted supertoughening of polylactide through hardening of the EGMA elastomeric domains of much low amount

The inherent shortcoming of brittleness for polylactide (PLA) was resolved through a facile melt blending of PLA with both ethylene-acrylic ester-glycidyl methacrylate random terpolymer (EGMA, a soft elastomer) and biobased polyamide copolymer (PUDA-co-BUDA, a hard elastomer). Surprisingly, the ternary blend containing PLA of 85 wt%, EGMA of 10 wt% and PUDA-co-BUDA of 5 wt% exhibited 26 times higher impact strength (64.2 KJ/m2) than that of neat PLA (2.4 KJ/m2), and superior stretchability with an elongation at break of 177%. Neither of EGMA and PUDA-co-BUDA could alone provide the same toughening effect at 10 and 5 wt%, respectively. Interfacial tensions between the component pairs and spreading coefficients of the ternary blends predicted the formation of hard-soft core-shell complex phase morphology, while scanning electron microscope (SEM) and transmission electron microscope (TEM) confirmed that the hard PUDA-co-BUDA domains were dispersed into the soft EGMA domains. The epoxy groups of EGMA reacted with the functional groups of PLA and PUDA-co-BUDA resulted in sufficient adhesions at PLA/EGMA and EGMA/PUDA-co-BUDA boundaries. The combined effect from both the unique particle microstructures and the interfacial adhesions led to obvious improvement in impact strength, opening a new avenue to expand the application of PLA-based products.

Automated summary

By blending PLA with EGMA and PUDA-co-BUDA, the impact strength of PLA can be significantly improved, along with enhanced stretchability. The unique particle microstructures in the ternary blend and interfacial adhesions between components play crucial roles in achieving these improvements.