The Key to High‐Ductile of Poly(Lactic Acid)/Poly (Butylene Adipate‐Co‐Terephthalate) Blends: Dicumyl Peroxide In Situ Compatibilization and Low Crystal Degree

ABSTRACT Poly(lactic acid)/poly (butylene adipate‐co‐terephthalate) blends (PLA/PBAT) with excellent biodegradability and mechanical properties are highly desirable for food packaging and biomedical applications. The uniform dispersion of PBAT in the PLA matrix and the improvement of the interface interaction between PBAT and PLA are key targets. In this work, PLA/PBAT blends were prepared by the melt mixing method with in situ reaction compatibilization of dicumyl peroxide (DCP). The experimental results showed that DCP can promote the uniform dispersion of PBAT in the PLA matrix, improve the interfacial interaction between the two, and form rapidly cooled amorphous specimens that exhibit higher flexibility. The PLA/PBAT/DCP (70/30/0.5) sample, which combines good processing performance and toughness, has a tensile fracture elongation and an impact strength that are 29.8 times and 49.2 times higher than pure PLA, respectively. It is proved that the cold crystallization of PLA was an important part of the blend process. Annealing at 80°C or 110°C, which is below or above the cold crystallization temperature, resulted in blends exhibiting decreased toughness, as the crystallinity increased from 2.56% to 24.96%. In conclusion, the fundamental elements that can maintain the high toughness of PLA/PBAT blends are effective interface compatibilization and low crystallinity.