Polypropylene nanocomposites based on C60-decorated carbon nanotubes: thermal properties, flammability, and mechanical properties

In the present study, the effects of covalently functionalized carbon nanotubes (CNTs) decorated with C-60 (abbr. C-60-d-CNT) on thermal, flame retardancy and mechanical properties of polypropylene (PP) are investigated. Compared with pristine CNTs, the C-60-d-CNT is more easily dispersed in the PP matrix through reactive compatibilization. With the incorporation of C-60-d-CNT, thermal oxidation degradation of PP is considerably delayed. Compared to PP, at 1.0 wt% loading of C-60-d-CNT, the initial degradation temperature (T-5) and maximum weight loss temperature (T-max) in air are enhanced by 68 degrees C and 87 degrees C, respectively. Furthermore, incorporating 1.0 wt% C-60-d-CNT can remarkably reduce the peak heat release rate (PHRR) by 71% relative to that of PP, and slow down the combustion process to some extent. The free-radical trapping effect of C-60 and the CNTs network are responsible for the improved thermal and flame retardancy properties. Meanwhile, addition of C-60-d-CNT also causes enhanced mechanical properties of PP nanocomposites to a certain degree.