Silicon rubber is the external insulation base material of composite insulator. A relationship between volume-resistivity and temperature may exists in virgin composite insulators

and may be affected by aging. Therefore

we tool silicon rubber as an object to investigate AC corona for different duration. Then volume resistivity in different temperatures was measured by the self-developed system to investigate volume resistivity and temperature characteristics（ ln 1v? ?T） of composite insulators. Experimental results show that

with the prolonging of AC corona

the linear correlation begins to deteriorate

particularly in low temperature area. With the combination of Fourier Transform Infrared Spectroscopy（FTIR） and X-ray Photoelectron Spectroscopy（XPS） test

the material surface will emerge large amount of micro molecule containing Si—O bound and the inner part of the insulator suffers less

influencing the volume resistivity and temperature characteristics. When temperature rises

linear property recovers to some extent due to the influences of movement of polymer chain segment and enlargement of movement volume.