Molecular simulation of nano polyhedral oligomeric silsesquioxane doping effect on the properties of two-component crosslinked epoxy resin

Abstract

Epoxy resin (EP) has been extensively used in the field of insulation for its excellent electrical strength, mechanical property, chemical stability, and low cost. In this paper, computer molecular simulation is used to analyze the influence of nano-POSS (Nano-Polyhedral Oligomericsils Esquioxane) doping on the properties of epoxy composite from the micro point of view, which can provide a scientific basis for the optimization of the epoxy system. Two kinds of nano-POSS fillers with different mass fractions were doped into the base material of diglycidyl ether of bisphenol A (DGEBA) and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecar (OSC). By molecular dynamics (MD) simulation the influence of nanofillers on the microstructure, thermal and mechanical properties of the composite were analyzed. Simulation results show that the doping of nano-POSS can improve the thermal and mechanical properties of the epoxy composite. Different nano-POSS has little effect on the glass transition temperature (Tg), coefficient of thermal expansion (CTE), and mechanical properties of the epoxy system, while the filling amount has an obvious improvement effect. Compared with EP/methyl-POSS system, the thermal and mechanical properties of the EP/phenyl-POSS system are better. At the same time, the doping of nano-POSS changed the microstructure parameters of epoxy composite. With the increase of nano-POSS filler content, fractional free volume (FFV) and mean square displacement (MSD) of both EP/POSS systems increased after the first drop. Besides, when the content of nano-POSS exceeded a certain range, the aggregation of filler itself hindered the accumulation of epoxy molecular chain segments.