Effect of maleic anhydride grafted poly(lactic acid) on rheological behaviors and mechanical performance of poly(lactic acid)/poly(ethylene glycol) (PLA/PEG) blends

A series of polylactic acid (PLA)/polyethylene glycol (PEG) blends was prepared by melt blending using PEG as a plasticizer to address the disadvantages of PLA brittleness. PEG can weaken the intermolecular chain interactions of PLA and improve its processing properties. PLA-grafted maleic anhydride (GPLA) was reactively blended with PLA/PEG to obtain a high tenacity PLA/PEG/GPLA blend. GPLA was prepared by melt grafting using diisopropyl peroxide as the initiator and maleic anhydride as the graft. The effects of different PEG molecular weights (1000-10 000 g mol-1) on the properties of PLA/PEG/GPLA blends were investigated. GPLA reacted with PEG1000 (Mw = 1000 g mol-1) to form short PLA branched chains and reacted with PEG10000 (Mw = 10 000 g mol-1) to form a small number of PLA branched chains, which was unconducive to increasing the intermolecular chain entanglement. The branched PLA formed by the reaction between PEG6000 (Mw = 6000 g mol-1) and GPLA had a remarkable effect on increasing intermolecular chain entanglement. The complex viscosity, modulus, and melt strength values of PLA/PEG6000/GPLA blends were relatively large. The elongation at break of the blends reached 526.9%, and the tensile strength was 30.91 MPa. It provides an effective way to prepare PLA materials with excellent comprehensive properties.