THERMAL AGING OF SILICONE OIL AROMATIC POLYAMIDE INSULATION SYSTEMS

The thermal degradation behavior of silicone oil/aromatic polyamide in sulation system was studied. It was found that the flash and fire poin ts decreased due to the formation of low molecular weight by-products of such cyclic siloxane oligomers as D-3, D-4 and D-5. The gel permiat ion chromatography (GPC) and high performance liquid chromatography (H PLC) analysis clarified that the depolymerization of siloxane molecule s happened during the thermal aging, resulting in the high- and low-mo lecular by-products formation. The thermal stability index (TGI) index obtained by the thermogravity (TG) measurements and cyclic oligomer d etection could be used for the insulation diagnosis.