In order to improve the toughness of polyoxymethylene (POM)

two elastomers

namely thermoplastic polyurethane (TPU) and polyolefin elastomer (POE

ethylene-octane copolymer)

were blended. The influence of crystallization behavior and microstructure evolution on the mechanical properties of pure POM

POM/TPU (85/15) and POM/POE (85/15) blends were examined. Large size spherulites of pure POM was found under polarizing microscope and a large number of micron-scale voids exist on the fracture surface of pure POM

which might be the main contribution to its poor notch impact strength. The voids as the defects of the material tend to form at the edge of the spherulites during the cooling or at the late stage of isothermal crystallization. Blending of the elastomers could significantly accelerate the crystallization rate of POM while reducing the size of the spherulites

which will reduce the number of voids and thus improve the toughness. For POM/TPU 85/15 blend

good compatibility between the two components and the large number of fine crystals coherently determine its significantly improved toughness and better tensile strength. While the poor compatibility between POM and POE with the interface restricted spherulite morphology make it exhibits discounted mechanical properties.