Molecular simulation of the effect of surface-modified nano-POSS on the properties of double cross-linked DGEBA/OSC composites

In order to analyze the effect of surface modification of nano-POSS on the properties of epoxy resin from a microscopic point of view, a composite model of modified POSS/epoxy resin was established by the molecular dynamics method. The effects of POSS surface functional groups on the structure and thermodynamic properties of epoxy composites were studied. Results show that surface-modified nano-POSS had certain effects on the thermal and mechanical properties of the epoxy composite system. Specifically, nano-P-phenyl-POSS and nano-A-phenyl-POSS can improve the glass transition temperature (Tg) and mechanical properties of the epoxy composite system while reducing the coefficient of thermal expansion of the system. The thermal and mechanical properties of the EP/F-phenyl-POSS system hardly improved. Among these composite systems, the EP/P-phenyl-POSS system exhibits the best modification effect. Tg was increased by 7.1 K. Young’s modulus, shear modulus, and bulk modulus were increased by 6.28%, 6.90%, and 3.77%, respectively. The reason is that surface-modified nano-POSS can change the microstructure of the epoxy composite system to different degrees and improve its compatibility with epoxy base materials.