Design of fully biodegradable super-toughened PLA/PBAT blends with asymmetric composition via reactive compatibilization and controlling morphology

Abstract

• PLA/PBAT blends with co-continuous structure have been fabricated. • Diisocyanate and stereocomplex crystallites of PLA are simultaneously used, for the first time, to achieve co-continuous structure in PLA/flexible polymer blend with asymmetric composition. • The fully biodegradable PLA/PBAT blends exhibit supertoughness with the notched impact strength of 62.6 kJ/m 2 . Super-toughened poly(lactic acid) (PLA)/poly(butylene-adipate-co-terephthalate) (PBAT) blends with co-continuous structure were successfully prepared by taking the advantage of reactive blending and stereocomplex (SC) crystallites located at the interface and poly(l-lactic acid) (PLLA) matrix. In order to generate SC crystallites, poly(d-lactic acid) (PDLA), PBAT and an isosorbide-based diisocyanate (IBDI) were firstly melt blended to prepare masterbatch. Then, it was melt mixed with PLLA to in situ form SC crystallites. Based on this two-step processing strategy, the influence of rotating speed of second mixing step on the formation of co-continuous structure is also investigated. Relatively low rotating speed (30 r/min) would lead to a more perfect co-continuous structure with superior impact strength of 62.6 kJ/m 2 compared with the blends mixed at the intermediate rotating speed (60 r/min). When the rotating speed increases to 90 r/min, the co-continuous structure breaks into irregular particles and the impact strength decreases to 30.0 kJ/m 2 .