Molecular dynamics study on thermal and mechanical properties of AOO modified DGEBA-anhydride insulating materials for high voltage GIS

Increases in rated voltage and power density of high voltage gas insulated switchgears (GIS) impose stringent requirements on the diglycidyl ether of bisphenol A (DGEBA)-anhydride thermoset, which is widely used as insulation materials for high GIS, for higher mechanical and heat-resistant properties. In this paper, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (AOO) was copolymerized with DGEBA -anhydride system to increase the mechanical and thermal properties of the thermosets. Based on the molecular dynamics simulation method, the coefficient of thermal expansion, glass transition temperature ( T g ), and modulus of AOO copolymer-modified DGEBA-anhydride thermosets were calculated. The AOO copolymer-modified DGEBA-anhydride thermosets specimens were further experimentally prepared and subjected to differential scanning calorimeter test, TGA test, tensile bending test, and dielectric test. The results of simulation and experiment simultaneously indicated that the T g and modulus of the DGEBA-anhydride thermoset are enhanced after AOO modification. This is mainly due to the decrease in free volume percentage and mean square displacement of the epoxy cross-linked network structure after the introduction of AOO molecules, which makes the structure more compact and the cross-link density increased. Additionally, the dielectric performances of the thermoset was enhanced by AOO. The excellent thermal, mechanical and dielectric properties of AOO modified DGEBA-anhydride thermoset make it a promising application in the field of high voltage GIS.