Properties of ladder-like polysilsesquioxane-modified insulation paper cellulose with different substituents

Abstract

Developing insulation paper with strong mechanical properties, low dielectric constant and high thermal stability is an important development direction in the power insulation industry. In this study, the effect of insulation paper cellulose (IP-Cellulose) doped with ladder-like polysilsesquioxane (LPSQ) and its derivatives (ladder-like polymethylsilsesquioxane (LPMSQ) and ladder-like polyphenylsilsesquioxane (LPPSQ)) was investigated by molecular dynamics simulation. The results showed that LPSQ and its derivatives can enhance the mechanical properties, thermal stability and dielectric properties of IP-Cellulose. Among the dopants, LPPSQ showed the best modification effect. Compared with those of pure cellulose, the volume, tensile and shear modulus of LPPSQ-modified IP-Cellulose were enhanced by 24.11%, 31.09% and 29.96%, respectively, the polarizability decreased by 39.83%, the cohesive energy density and solubility significantly increased. In addition, the mean square displacement clearly decreased and the free-volume fraction decreased by an average of 7.29%. Further analysis of the modification mechanism showed that LPPSQ had better dispersion stability, higher interaction energy and stronger inter-molecular force in IP-Cellulose, which further enhanced the stability of the composite system. The results of this study will enrich the application of LPSQ in insulation materials, and they provide an important basis for the development of high-performance insulation paper in ultrahigh-voltage power systems.