The thermal expansion behavior of polymer carbon nanotube (CNT) nanocomposites was investigated, and a micromechanical model was proposed to explain the highly nonlinear dependence of the coefficient of thermal expansion of the nanocomposite with CNT content for the CNT/polyimide nanocomposite. The proposed micromechanical analytical model was found to correlate closely with the experimental results for polyimide/CNT nanocomposite films as measured using a digital image correlation method  (Research Gate link).