Designing of reactive micro-crosslinked PBAT as the efficient biodegradable toughener for PLLA

Abstract

Melt blending with biodegradable poly (butylene adipate-co-terephthalate) (PBAT) represents a facile strategy to toughen poly (l-lactide) (PLLA). Unfortunately, the toughening efficiency of PBAT is far from the practical requirements regardless of significant efforts to strengthen interface between PLLA and PBAT phases. Herein, two reactive micro-crosslinked PBAT tougheners (RMBTs) via simple reactive processing of PBAT/glycidyl methacrylate (GMA)/dicumyl peroxide (DCP) with or without PLLA-inclusions have been designed to break the toughening restriction of PBAT for PLLA. The results indicate that the RMBT without PLLA increases the toughness of the final PLLA blends in comparison to pristine PBAT. Intriguingly, further enhancements can be achieved by using the RMBT incorporating PLLA moieties. The notched impact strength of the PLLA-incorporated RMBT toughed PLLA is as high as 52.3 kJ/m2 at 30% PBAT content, which is 600% higher than the pristine PBAT toughed PLLA, while the tensile strength keeps almost the same value of about 44.4 MPa. The collaborative enhancement is not only attributed to the micro-crosslinking and reactive group grafting modification, but also ascribed to sub-inclusion of rigid PLLA chains in the PBAT phase. The comprehensive mechanical properties of the fully biodegradable PLLA blends are even higher than those of the commercially available polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends. The high toughening efficiency of the reactive micro-crosslinked PBAT would evoke new inspiration in the field of industrial manufacture of fully degradable PLLA blends with high stiffness-toughness balance.