The effect of BN/Al ₂ O ₃ in-situ self-assembling on thermal conductivity of polypropylene composites

In this work, γ-aminopropyltriethoxy silane (KH550) and γ-(2,3-epoxypropoxy)propyltrimethoxy silane (KH560) were used to modify BN and Al ₂ O ₃ , and described as KH550-BN and KH560-Al ₂ O ₃ with amino and epoxy group on surface, respectively. KH550-BN and KH560-Al ₂ O ₃ were filled in polypropylene (PP) matrix by twin-screw extruder. The thermal conductivity of composites increased with increasing catalyst dosage, material residence time in barrel and homogenization section temperature of twin-screw extruder. Hybrid fillers with semi core-shell structure were formed by KH550-BN in-situ reacting with KH560-Al ₂ O ₃ though amino and epoxy group. KH550-BN and KH560-Al ₂ O ₃ were pre-assembled in toluene and filled into PP to prepare composites, which thermal conductivity increased with increasing pre-assembling time. The experimental results show that KH550-BN and KH560-Al ₂ O ₃ do in-situ self-assemble in PP melt. The thermal conductivity of composites with in-situ self-assembling had 21.6% improvement than that of composites with no assembling. A low-cost, simple and efficient method for preparing thermally conductive and insulating composites is realized.