Molecular Dynamics Simulations on Epoxy Resin Composite via Grafting Acryloyl-chloride to Inhibit Electron Transport and Improve Thermal-mechanical Properties

Electrical, thermal, and mechanical properties of cross-linked epoxy resin (EP) modified by the chemical grafting of acryloyl chloride (AC) were studied to explore the trapping mechanism of charge transport inhibition. The bound state traps deriving from grafted molecules were analyzed by first-principles calculations combined with electron transmission spectra to study the underlying mechanism of the electrical properties. In contrast to pure EP, the EP-graft-AC (EP-g-AC) represents significantly depressed conductivity due to the electron scattering from polar-groups of the grafted AC molecule. The substantial deep traps are generated in EP-g-AC molecules by the polar group of grafted AC and accordingly decrease charge mobility and raise the charge injection barrier, consequently suppressing space charge accumulation and charge carrier transport. EP-g-AC polymer acquires a significant amelioration in thermal and mechanical properties, as indicated by the higher cohesive energy density, glass transition temperature, and decomposition temperature in consistence with the lower thermal vibrations compared with pure EP polymer, except that the resulting higher fractional free volume is not preferable, which is attributed to the mixing incompatibility of the grafted AC molecules with EP molecular-chains.