Effect of zinc borate on mechanical and dielectric properties of metallocene linear low-density polyethylene/rubbers/magnesium oxide composite for wire and cable applications

The effect of zinc borate (ZB) quantity on the mechanical and dielectric properties of 20 phr magnesium oxide/10 % rubbers (9/1 NR/ENR-50)/metallocene linear low-density polyethylene (mLLDPE) in the presence of N,N-m-phenylene bismaleimide (HVA-2) compatibilizer was investigated for wire and cable applications. With the increase in ZB loading, the tensile strength and the elongation-at-break of the composites decreased while the tensile modulus increased. In all composites, the strain-induced crystallization phenomenon at 200 % elongation was being observed in the stress–strain curves. Moreover, the dielectric strength, dielectric loss, permittivity and volume resistivity at frequency of 50 Hz were investigated. The permittivity of all composites increased with a rise in the voltage within the range of 1–5 kV. The loading of ZB in the composites improved the permittivity and volume resistivity as compared to the neat mLLDPE. The dielectric loss increased and 2 phr ZB composite displayed the highest dielectric loss among all other composites. On the other hand, the breakdown decreased with increasing ZB loading and the highest breakdown was observed in the 6 phr ZB composite. It was concluded that all composites are suitable for wire and cable application and the best result based on dielectric properties was observed in the 6 phr ZB composite.