Abstract: Polyacetal (POM)/ethylene-vinyl acetate copolymer（EVA）compounds were melt blended by a twinscrew extruder. Mechanical properties, crystallinity and morphologies of the compounds were investigated. The results indicated that notched impact strength of the compounds was improved effectively with addition of EVA and increased with the EVA content, but their flexural modulus and tensile strength decreased gradually. The presence of EVA influenced the crystallization behavior of POM and resulted in a decrease in crystallinity of POM. Transmission electron microscopic observation revealed a clear interface between the two phases, indicating poor compatibility between the two polymers. However, a wide particle-size distribution was observed for the dispersed phase, which may favor the toughening of POM.

Key words: polyacetal, ethylene-vinyl acetate copolymer, toughening, mechanical property, crystallinity, morphology