Effect of different carbodiimide additives on the compatibility and hydrolytic behavior of PLA/PBAT blends

Abstract

Blends of Polylactic acid (PLA) and Poly(butylene adipate-co-terephthalate) (PBAT) have great potential to replace conventional polyolefin and polyester materials. However, poor compatibility and fast degradation rate limit its development. In this paper, the effect of two monomer-type carbodiimides and one polymerized carbodiimide on the mechanical, crystalline, thermal stability, and hydrolysis properties of PLA/PBAT blends are investigated. Tested by FTIR, SEM, DSC, TGA, GPC, MFR, terminal carboxyl content, tensile properties and rotational torque. It is found that all the three carbodiimide additives improve the compatibility, enhance the mechanical, processing, and thermal stability properties of PLA and PBAT blends except for their reduced crystallization performance. Moreover, regarding the hydrolysis properties, the two monomeric carbodiimides exhibit little effect on the hydrolysis of PLA/PBAT blends, especially when the degradation conditions are alkaline, and even accelerate the degradation rate. Howover, the anti-hydrolysis effect of polycarbodiimide is remarkable, thus effectively enhancing the compatibility and anti-hydrolysis properties of PLA/PBAT blends, which is confirmed to be the most effective additive in this study.