Application of phosphogypsum as solid waste in poly(lactic acid)/poly(butylene adipate‐co‐terephthalate) composite

Abstract Phosphogypsum (PG) as one of the largest amounts of industrial solid wastes, is simply pretreated by the conventional lime neutralization method to apply for the preparation of PG/PLA‐GND/PLA/PBAT composite through melt blending in this work, where PLA grafted with glycidyl decanoate (PLA‐GND) is used as a non‐reactive compatibilizer. The hydroxyl groups of PG particles could form internal hydrogen bonds with the ester groups, terminal hydroxyl groups, and terminal carboxyl groups of PLA or PBAT chains, which would promote the uniform dispersion of PG particles in the PG/PLA‐GND/PLA/PBAT composite and the generation of a network structure with PG particles as the physical crosslinking points in the PG/PLA‐GND/PLA/PBAT composite. Moreover, the PG particle acts as a heterogeneous nucleating agent to assist the crystallization of the PLA chain and improves the crystallinity of the PG/PLA‐GND/PLA/PBAT composite. Therefore, when the PG additive amount is 0.75 g, the tensile strength, flexural strength, impact strength, and heat distortion temperature of the PG/PLA‐GND/PLA/PBAT composite are 43.87, 55.98 MPa, 17.13 kJ/m 2 , and 78.6°C, which are 13.83%, 10.33%, 8.21%, and 20.37% higher than those of the PLA‐GND/PLA/PBAT composite and 30.45%, 47.59%, 82.82%, and 34.82% higher than those of the PLA/PBAT composite, respectively. Highlights Pretreated PG without surface modification is dispersed evenly in the PLA/PBAT composite. The hydrogen bond between PG and PLA or PBAT promotes the dispersion of PG particles. A network structure forms in composite due to the existence of hydrogen bonds. PG particle acts as a heterogeneous nucleating agent to raise the crystallinity of the composite. Pretreated PG improves the thermal and mechanical properties of the PLA/PBAT composite.