Toughening of poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate) (PBAT): a morphological, thermal, mechanical, and degradation evaluation in a simulated marine environment

In this study, blends at different concentrations of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) were developed using poly(styrene-co-maleic anhydride) (AG) as a compatibilizer to improve the toughness without losing biodegradability. The blends were prepared by an extrusion process followed by injection to evaluate their morphological, thermal, and mechanical properties. Degradation in a simulated marine environment was evaluated by residual mass, morphology, and tensile strength after different exposure times. The polymer blend of these polymers showed immiscibility, and the compatibilizer promoted the interaction between the phases. The results showed an increase in impact strength from 27 to 109 J m⁻¹ with the addition of 80 wt% of PBAT, with a significant difference in impact strength, additionally a decrease in elastic modulus from 1063 (pure PLA) to 95 MPa (PLA/PBAT/AG 20/80), accompanied by an increase in elongation at break from 2.2 to 35%, proving an increase in toughness of PLA when adding PBAT. As for the biodegradation test, the morphological results of the loss of integrity on the surface of all the compositions after 30 days in a simulated marine environment are striking, especially for the composition with 80 wt% PBAT, accompanied by a yellowing of the samples and the development of a biofilm on their surfaces. The decrease in elongation at break upon exposure showed an increase in brittleness, a characteristic behavior of the biodegradation of the samples. The highest amount of PBAT in the blends favored the degradation of PLA in a simulated marine environment during the time studied.