Degradation and Dynamic Properties of Poly(amide-co-imide)/Carbon Nanotube Composite Films

Poly(amide-imide) (PAI)/carbon nanotube (CNT) composite films were investigated through FT-IR spectroscopy, TGA, and DMTA measurements in order to understand the interrelationships of surface modification of CNTs, thermal imidization time, and thermal stability after they were prepared by solution mixing. Thermal stability and glass transition temperature were significantly improved when the PAI/CNT nanocomposites were filled with hydrogen peroxide treated CNTs (p-CNT) because the dispersion of p-CNTs and interfacial bonding between p-CNT particles and PAI molecules were improved. The imidization time of the PAI/p-CNT composite film needed for sufficient imidization reaction was reduced by about 3 hours compared with that of the pure PAI film, because p-CNTs have higher thermal conductivity than the pure PAI resin. They also showed the highest glass transition temperature among all PAI/CNT composites since p-CNTs have many hydrophilic functional groups which yield strong interaction with PAI molecules. It was found that the thermal imidization depended on the network structure which was generated by the crosslinking reaction and surface modification of CNTs.