Tensile strength research of PC and PET under high temperature in mineral oil

Insulation paper is a very important part of internal insulation in oil-immersed transformers. The performance of oil-paper insulation and quality are directly related to the reliability and service life of the transformers. The defect of insulating paper, such as high dielectric constant, poor high temperature resistance, easily decomposition limited the oil-immersed transformers development in the direction of the large capacity, small volume. Therefore looking for a new material with superior insulation performance, excellent heat resistance, and low cost to replace the insulation paper will provide new possibilities for the development of the transformers. In this paper, the major research is the solid material properties of Polycarbonate (PC) and Polyester (PET), two kinds of polymer. Making a contrast with insulation paper, we had 300 days of aging test under 90°C, 110°C, 130°C. By the means of tensile strength tests, we can get the change rules of the material´s tensile strength. Comparing with the degree of polymerization, we can get the corresponding relationship between tensile strength and the degree of polymerization. By comparing the change of tensile strength of the above insulation materials under three kinds of aging temperatures, analyzing the reasons of evolvement, we can find the development prospect and further application value of the polymer materials.