Tailoring the nonlinear conducting behavior of silicone composites by ZnO microvaristor fillers

Silicone composite filled with zinc oxide microvaristors possesses excellent nonlinear conducting behavior as ZnO varistor does. For better adjusting the composite's electrical behavior to satisfy the practical field-grading requirement, this article studied the influence of ZnO filler's property on the nonlinearity of the composite. Several groups of ZnO-silicone composite samples in different filler volume fraction and filler diameter were prepared, the measured J-E characteristics show that the percolation threshold of ZnO-silicone composite is around 35%, above which the composites present reliable nonlinear behavior. The switching voltage of the composite exhibits a considerable decrease as filler's diameter increases or filler's volume fraction increases, while the nonlinear coefficient remains stable. Moreover, filler's size also has a little influence on composite's percolation limit. The conclusion above fits very well with the theory of the conducting composites and percolation process. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42645.