Influence of Moisture Absorption on Space Charge Accumulation in Liquid Silicone Rubber Under High DC Electric Field

Dielectric elastomer (DE) possesses great potential in application for ocean wave energy conversion (WEC) due to favorable stretchability, high energy conversion efficiency, fast electromechanical response and low loss. As a critical component of WEC system, DE materials are inevitably exposed to moisture absorption which may deteriorate the mechanical and electrical properties, further affecting the longterm operation and service life of the system. Moreover, when a high DC voltage is applied, the injection, accumulation and transport of space charge transport will distort the electric field distribution in the dielectric, which is related closely to the breakdown performance. In this paper, liquid silicone rubber (LSR) films, were put in a chamber with high humidity (97%) at 56.5℃ to absorb moisture for different amounts of time. The effect of water absorption on space charge behavior of LSR and post-cured LSR under different applied DC electric fields is discussed using a pulsed electro-acoustic method (PEA) measurement system. The results show that the post-curing process reduces the charge accumulation and modifies the electric field distribution in LSR. The accumulated charge is seen to increase with increasing water uptake, in both LSR and post-cured LSR. The maximum electric field distortion of wet post-cured LSR is lower than wet LSR.