Influence and mechanism analysis of acid or alkali damp environment on insulation performance of distribution cable accessories

•The artificial damp simulation experiments were conducted in different acidic and alkaline environments.•The physicochemical and electrical properties of XLPE and SIR specimens are evaluated.•Strong alkali has the strongest corrosive effect on specimens, with the most severe degradation of electrical properties.•The Material Studio is used to simulated the effect for electrical properties of breakage molecular chain.