Nucleation and Crystallization of Polymer/MWCNT Nanocomposites

摘要

Isothermal and non-isothermal crystallization behavior of polymers can be investigated with traditional calorimeters often in a limited temperature region only. This results from the fast crystallization processes on optimal conditions, which appears in most polymers in a few seconds or less. The chip-based fast scanning DSCs allow applying heating and cooling rates of several 1000 K/s, which enables for many polymers to follow crystallization in the whole temperature range between glass transition temperature and melting temperature. We applied the new chip calorimeters for the investigation of crystallization kinetics of PET, PBT, PCL and their MWCNT composites with different filler contents under non-isothermal and isothermal conditions. The MWCNT act as nucleating agents for all three polymers and speed up crystallization at high temperatures, where heterogeneous nucleation dominates, for about one order of magnitude. At low temperatures, where homogeneous nucleation can be assumed, crystallization kinetics is independent on filler content. Detailed investigation of cold crystallization after different annealing procedures allows the determination of kinetics of nucleation too and will be discussed for PCL and its composites.