AbstractBinary bio-composites of acorn shell (AS) and low density polyethylene (LDPE) were prepared via a twin-screw extruding method. The mechanical properties of the composites decreased with increasing AS content, and all composites maintained similar tensile strength as expected based on the Nicolais-Narkis model, indicating weak adhesion between AS and LDPE. The effects of three compatibilizers, ethylene-acrylic acid (EAA), ethylene-vinyl acetate (EVA), and maleic anhydride grafted polyethylene (PE-g-MAH) on the composites were also studied. The results showed that the three compatibilizers improved the mechanical properties of composites at different levels, and the PE-g-MAH compatibilizing system showed the best mechanical strength, which was increased by about 80% from that of the control. Micro-morphologic investigation revealed a rough fractured surface, indicating that the addition of compatibilizers improved the interfacial bonding properties of the matrix materials LDPE matrix. Dynamic mechanical thermal analysis (DMA) further confirmed that the addition of compatibilizers significantly improved the compatibility of blending components and changed the properties of LDPE matrix materials.