Abstract:
This paper aims at dispersing nano Al
2O
3 in polyethylene(PE) and ethylene vinyl acetate copolymer (EVA) blends to build thermal conductive composites with high local particle concentration and selective distribution structure. With nano Al
2O
3 as thermal conductive filler, PE and EVA as matrix resin, Al
2O
3/PE-EVA thermal conductive composites were prepared by melt blending method. The phase structure of PE-EVA blends and distribution of Al
2O
3 in blends were investigated by selective solution extraction method and SEM. The thermal conductivity and mechanical properties of Al
2O
3/PE-EVA composites were evaluated. The results show that blends with two-phase co-continuous structure are obtained at PE to EVA mass ratio of 1:1. By introducing Al
2O
3 into PE-EVA two-phase co-continuous blends, Al
2O
3 is mainly dispersed in PE phase. The distribution behavior of Al
2O
3 and the formation of co-continuous structure are helpful to improve the thermal conductivity of composites. 21.2% increase of thermal conductivity is obtained for Al
2O
3/PE-EVA composites with selective distribution and co-continuous structure, in comparison to that of Al
2O
3/PE composites at Al
2O
3 mass fraction of 50%. With the increase of Al
2O
3 mass fraction, the tensile strength of Al
2O
3/PE-EVA composites tends to be similar to that of Al
2O
3/PE composites. The elongation at break of Al
2O
3/PE-EVA composites is also superior than that of Al
2O
3/PE composites thanks to the toughing effect of EVA phase.