High-performance biosourced poly(lactic acid)/polyamide 11 blends with controlled salami structure

Abstract

High-performance biosourced poly(l-lactide) (PLLA)/polyamide 11 (PA11) (55/45) blends with small amounts of rubber, ethylene glycidyl methacrylate-graft-styrene-co-acrylonitrile (EGMA-g-AS), were fabricated by simple melt compounding. Epoxide groups in EGMA-g-AS are ready to react with both PA11 and PLLA, and thus EGMA-g-AS could be manipulated to locate mainly in either PA11 phase or PLLA phase by variation of the blending sequence. It was found that the blend with salami structure in which EGMA-g-AS is predominantly dispersed in the PLLA phase provides not only significantly improved tensile ductility, but also excellent film impact strength, while keeping relatively high modulus. The elongation at break and the film impact strength of such materials with 6 phr EGMA-g-AS are 322% and 361 kJ m−2, which are 78 and 5.2 times those of unmodified PLLA, respectively. In contrast, the blends with EGMA-g-AS mainly in the PA11 phase fracture in a brittle mode with low toughness. The toughening mechanism of the PLLA/PA11 blends with the sub-inclusion salami structure was investigated using a double-notch technique. The brittle-to-tough transition was observed on increasing the rubber sub-inclusion concentration in the PLLA phase. © 2013 Society of Chemical Industry