Bio-based epoxidized cardanol sorbate as an interface-localized compatibilizer for enhancing poly(lactic acid) (PLA) and poly(3-hydroxybutyric acid-co-4-hydroxybutyric acid) (P34HB) blend

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PLA is a bio-based polyester with limited barrier and flexible properties. Adding poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P34HB), a biodegradable polyester known for its outstanding barrier properties, was the strategy employed to boost PLA performance. However, the blend’s immiscibility necessitates compatibilizers to bolster interfacial adhesion and dispersion. This study designed a novel bio-based compatibilizer, epoxidized cardanol sorbate (ECD-SA), to improve the compatibility of the blend. The molecular design of ECD-SA has been optimized to minimize steric hindrance, thereby enhancing interfacial reactions more effectively. Two commercial compatibilizers, specifically ADR 4468 and NC-514, were selected for comparison. Theoretical model was employed to calculate dispersion preferences of three different compatibilizers in the blend. A systematic investigation was carried out to analyze the effects of compatibilizers on the structure and properties of PLA/P34HB blends. The findings suggest that ECD-SA functions as an interface-localized compatibilizer in PLA/P34HB blends, enhancing their compatibility and performance significantly. Specifically, the incorporation of 2 phr (parts per hundred resin) ECD-SA into the PLA/P34HB film resulted in a marked increase in tensile strength from 35.6 MPa and 23.5 MPa to 48.6 MPa and 36 MPa in the longitudinal and transverse directions, respectively, and an increase in elongation at break from 31.9 % and 9.2 % to 104.8 % and 48.3 %, respectively. This underscores its significant potential as a compatibilizer for PLA/P34HB, pointing towards extensive application possibilities in present-day packaging industries.