Molecular investigation on temperature-dependent mechanical properties of PMMA/CNT nanocomposite

Abstract

Carbon nanotube (CNT)-reinforced poly (methyl methacrylate) (PMMA) composite is subjected to changing temperature levels when used in aerospace field, which leads to the morphing structure and changing properties, and even structural failure. In this paper, the temperature effect on the structure and properties of PMMA/CNT nanocomposite with different CNT volume fractions is investigated using molecular dynamics (MD) simulation. It is measured that with increasing temperature from 100 to 500 K, the longitudinal, transverse, and shear moduli of PMMA/CNT nanocomposite decrease by 30 %, 45 %, and 62 %, respectively, while the coefficient of thermal expansion (CTE) increases by 27 %. It is found that the atom distribution becomes more dispersed and the nanocomposite structure turns to looser, which lead to the weakened properties of the nanocomposite. Based on the MD results, the efficiency parameters of PMMA/CNT nanocomposite are derived using extended rule of mixtures (EROM), which are used to predict the mechanical properties of nanocomposite at different temperatures. The revealed temperature-dependent mechanical properties and the underlying mechanisms contribute to the understanding of performance changes of PMMA/CNT nanocomposite under the temperature effect, which provide references for the application of composite materials in the aerospace field where the changing temperatures are of highly concern.