Mechanical and Thermal Properties of Reactable Nano-SiO<sub>2</sub>/polyoxymethylene Composites

Abstract

The polyoxymethylene-based composites containing reactable nano-SiO2were prepared in a twin-screw extruder by melt compounding, and mechanical and thermal properties of pure polyoxymethylene (POM) and composites were investigated. The results showed that reactable nano-SiO2could reinforce the tensile strength and Young’s modulus of composites. To the impact strength of composites, there was obvious improvement when a small amount of silica was added into POM. With the increase of silica content, the impact strength of composites showed a gradually decrease trend. It was worthy to note that reactable nano-SiO2could significantly increase the decomposition temperature of POM. When the content of reactaSubscript textble nano-SiO2was up to 5 wt%, the degradation temperature of composites could increase about 38.3°C under nSubscript textitrogen atmosphere and 43.8°C under air atmosphere, respectively, compared with pure POM. Furthermore, the differential scanning calorimetry (DSC) analysis showed that reactable nano-SiO2had a good heterogeneous nucleation capability in POM, and could increase crystallization temperature of POM, but surface structure of reactable nano-SiO2was not propitious to the growth of POM crystals, accordingly leading to the decreasing crystallinity of composites.