Investigation of the Effects of Temperature and Strain on the Damping Properties of Polycarbonate/Multiwalled Carbon Nanotube Composites

Abstract

The effects of temperature and strain on the free volume and damping properties of polycarbonate/multiwalled carbon nanotube (PC/MWCNT) composites were investigated by positron annihilation lifetime spectroscopy and dynamic mechanical thermal analysis. The damping dependence on temperature indicated that the damping factors remain at a low constant value in the polymer glassy state and increase rapidly in the glass-transition area. During the glass-transition area, a direct linear relationship between the fractional free volume and the damping has been obtained using the Williams–Landel–Ferry equation based on the free volume theory, which indicates that the free volume plays an important role in determining the damping property. The strain–damping experiments reveal that a high damping factor is still obtained. A “stick–slip” model has been used to analyze the damping dependence on strain for PC/MWCNT composites, which reveals a damping mechanism of interfacial slip between the MWCNTs and the matrix.