Role of interface between BNNS and LDPE in excellent electrical, thermal and mechanical properties of LDPE/BNNS composites

It is still challenging in obtaining an insulation material with high thermal conductivity and excellent mechanical properties, while suppressing the distribution of space charges. In this article, exfoliated hexagonal boron nitride nanosheets (BNNS) were introduced into low-density polyethylene (LDPE) to optimize the electrical, thermal and mechanical properties of LDPE-based composites. The results show that the obtained LDPE/BNNS composites possess enhanced thermal conductivity, suppressed space charge distribution, higher breakdown strength and excellent mechanical properties. The nanoscale interfaces (about 2.0 nm) between BNNS and LDPE in the composites are detected by small angle X-ray scattering (SAXS) technique and in-situ SAXS is employed to investigate the variation of interface during stretching process. Acquired information suggests that the strong interface interaction is beneficial to suppressing space charge distribution, enhancing breakdown strength and improving mechanical properties of the composites except increasing interface thermal resistance. This work would provide a candidate insulation material and present a new recognition of the role of interface in enhancing the properties of LDPE-based composites.