Abstract: With PET/MMT composite system as the substrate，using polyethylene grafted maleic anhydride（PE-g-MAH），maleic anhydride grafted polyethylene octene elastomer（POE-g-MAH），and polypropylene grafted maleic anhydride （PP-g-MAH） as the toughening agent，melt blending them with a twin-screw extruder. We studied the effects of different toughening agents on the composite system′s mechanical properties，compatibility， and melt crystallization behavior. The results showed that adding the toughening agent into PET/MMT composite system had an excellent toughening effect. When the amount of POE-g-MAH added was 30%，the notched impact strength was 2.4 times that without the toughening agent. Infrared characterization showed that toughening modification could improve the compatibility of PET/MMT. XRD results showed that the toughening agent had no effect on the PET/MMT composite crystal structure，and its mechanical properties and processing properties could be improved by melt toughening. DSC results showed that the addition of tougheners could reduce the cold crystallization temperature of PET/MMT blends. SEM results showed that adding tougheners could increase the bonding force between the interfaces，which effectively improved the compatibility of the PET/MMT blend system.

Key words: polyethylene terephthalate （PET）, montmorillonite （MMT）, toughening, mixing, composite materials