Abstract: This paper reported an investigation on the effect of ultraviolet (UV) crosslinking on thermal elongation, mechanical properties and flame retardancy of an insulation material used for low-smoke halogen-free flame-retardant cables. The thermal stability and aging behavior of the insulation material were also studied by thermogravimetric analysis. The results showed that the thermal elongation of insulation material decreases gradually with an increase in UV irradiation time, and its mechanical properties, heat resistance, and flame retardant and electrical performance were greatly enhanced due to UV crosslinking. The tensile strength of the insulation material was improved from 10 MPa to 13 MPa after UV crosslinking. With a thermal aging test at 158 ℃, both the tensile strength and elongation at break achieved a retention rate above 90 %, and the limiting oxygen index also increased from 33.5 % to 35.0 %. Moreover, the volume resistivity and dielectric strength were improved to 7.8×1012 Ω·m and 36.0 MV/m from 1.1×1013 Ω·m and 33.0 MV/m before UV crosslinking, respectively

Key words: cable insulation material, UV crosslinking, low-smoke halogen-free capacity, thermal stability, flame-retardancy