Effect of Bonded Interfacial Structure on Mechanical Properties of Polyimide/SiO2 Composites: Molecular Dynamics Simulations

Abstract

AbstractThe effect of covalent bonds and the SiO2 concentration on the interface structure and the performance of polyimide/SiO2 (PI/SiO2) composites is investigated by molecular dynamic simulation. To enhance the interface interaction, the silica coupling agent is treated as a bridge to connect PI chains with SiO2 particles. The SiO2 content is controlled by adjusting the number of PI chains. The results show that the bonded interface structure not only increases the interfacial non‐bond energy and the number of the hydrogen bonds, but also strengthens the tensile strength, Young's modulus, shear modulus, and the glass transition temperature of the composites. As the SiO2 concentration increases, the non‐bond interaction energy between each PI chain and SiO2 particle increases and the non‐bond interaction energy in the bonded composites are higher than that of the unbonded. The number of hydrogen bonds in the bonded composites is sensitive to the SiO2 concentration, but there is no obvious relationship in the unbonded composites. Young's modulus and shear modulus of PI/SiO2 composites are higher than that of the unbonded at the same doping concentration. Therefore, establishing the bonded interface structure is an effective way to improve the interface stability and the properties of composite materials.