Investigation of Thermal Expansion of Polyimide/SiO2 Nanocomposites by Molecular Dynamics Simulations

In this paper, an atomistic model for PI/SiO2 hybrid nanocomposites was designed for the investigation of physical properties of this material on the base of molecular dynamics simulations. The thermal properties of a reference pure PI matrix in the temperature range of 300-650 K were first investigated. The results for the CTE and the glass transition temperature showed good agreement with the experimental data. Then, the thermal expansion of the model of PI/silica composite material with different SiO2 fractions was investigated at normal conditions. The CTE of the composite model decreases with the increase in the SiO2 content in agreement with experimental studies. The results show a threshold for the SiO2 loading beyond which the material model exhibits ultra-low thermal expansion.