High thermal conductivity and high impact strength of epoxy nanodielectrics with functionalized halloysite nanotubes

Epoxy nanodielectrics with high thermal conductivity and high impact strength have become the increasingly desirable material of the electronic and electric industries. In this paper, three functionalized halloysite nanotubes (HNTs) named p-HNTs (treated by KH 560), b-HNTs (in situ grafted by benzidine) and d-HNTs (in situ grafted by 4,4′-(1,1′-biphenyl-4,4′-diyidioxy)dianiline) were used to fabricate thermally conductive epoxy/HNTs nanodielectrics with a high impact strength. It was found that the surface modification of HNTs play very important roles in enhancing the mechanical, thermal and dielectric properties of epoxy nanodielectrics. The obtained epoxy/b-HNTs nanodielectrics with 60 wt% filler presented the highest thermal conductivity of 0.85 W m^-1 K^-1 (about 30% higher than that of epoxy/HNTs nanodielectrics). The impact strength of epoxy/b-HNTs nanodielectrics is about 5.8 kJ m^-2, 1.5 times that of epoxy/HNTs nanodielectrics. The epoxy/b-HNTs nanodielectrics also possessed excellent thermal stability and electrical insulation properties. In summary, the epoxy/b-HNTs nanodielectrics showed the best overall performance among all epoxy thermosets/in situ grafting HNTs. The results of the SEM images showed that the improved physical properties of epoxy nanodielectrics were attributed to the increased interaction between in situ grafted HNTs and the epoxy matrix and better dispersion of the in situ grafted HNTs in the epoxy matrix. The results suggested that the obtained epoxy nanodielectrics might be promising as efficient heat-releasing materials for thermal management and next generation electronic devices.