Study on the Effect of Branch Degree of Hyperbranched Polyester on Thermomechanical and Dielectric Properties of SiO2/EP

In this article, the effect of branching degree (DB) on SiO2/EP modified by hyperbranched polyester was investigated through simulation, and the experiment was used for verification. Nine models of polymers modified with hyperbranched polyesters with different DB and one model of polymers modified with silane coupling agent KH560 were established. Then, their thermal conductivity (TC), glass transition temperature, mechanical properties, and dielectric constants were calculated. The results reflect that as the DB increases, the TC, mechanical properties, and dielectric constant increase, but the glass transition temperature decreases. The relevant experiments were conducted, and the results also confirm this trend. According to the simulation microstructure analysis, the mean square displacement (MSD) and free volume fraction increase as the DB increases, which leads to a decrease in the glass transition temperature; the increase in the number of hydrogen bonds and binding energy provides the basis for the increase in TC, mechanical properties, and dielectric constant.