236 / 2022-03-14 21:07:55

Molecular dynamics simulation of polydimethylsiloxane under different temperature and electric field

composite insulator; methyl siloxane; molecular dynamics; electric field strength; temperature

Purpose/Aim

The internal electric field intensity of UHV composite insulator is high during operation, and high temperature may be generated during partial discharge. Under the action of strong electric field and high temperature, the aging problem of silicone rubber will be more prominent, but the deterioration process is difficult to be characterized by macro characteristics.

Experimental/Modeling methods

Based on molecular dynamics simulation, a molecular model of methyl vinyl silicone rubber was established to explore the structural evolution and micro characteristic changes of silicone rubber under the action of temperature, pressure and electric field, and further study the changes of mechanical properties of silicone rubber. In the simulation system, a molecular chain is constructed with Material Studio software, the stable structure is obtained through geometric and energy optimization, and the unit cell parameter is set to 30 Å × 30Å × 30 Å, and then use Amorphous Cell to construct crystal cells with molecular chain number of 10 in three different temperature systems, and the density is set to 0.98g/cm3. Finally, different morphological structure and mechanical property parameters are simulated with Forcite module under different pressure and temperature and Castep module under different electric field, and the changes of molecular temperature, electric field and pressure are analyzed.

Results/discussion

It was found that the texture of silicone rubber softened and the mechanical properties decreased with the increase of temperature; However, the increase of electric field strength makes the texture of silicone rubber hardened and the mechanical properties enhanced; In the same temperature system, with the increase of pressure, the smaller the elastic modulus, the stronger the flexibility of the material.

Conclusions

The research results can establish a theoretical basis for the relationship between the micro morphology and macro characteristics of silicone rubber materials, and then provide reference value for the optimization of substrate for composite insulator.