Abstract: Walnut shell powder (WSP) was treated with a silicane coupling agent KH550 and was introduced into poly(lactic acid) (PLA) forming composites through melt blending. The effect of the surface treatment of WSP was studied. When the dosage of KH550 was 6wt% of the walnut shell, all the tensile, bending, and impact strengths of PLA/WSP composites were increased by 1.2 times, reached 42.09, 63.89 MPa, and 1.69 kJ/m2, respectively. SEM images indicated the compatibility between WSP and PLA was improved after surface modification. When the contents of WSP were 5 wt % and 40 wt %, the thermal degradation activation energies (Ea) of composites were 13.1 and 29.8 kJ/mol lower, respectively, than those of neat PLA. The surface treatment depressed the decrease in degradation activation energy.

Key words: poly(lactic acid), walnut shell, silicane coupling agent, surface modification, mechanical property, thermal stability