Carbon nanotubes suppressed crystallization kinetics in PLLA thin film as revealed by in situ RAIR technique

The bulk and thin film crystallization behaviors of PLLA/CNTs nanocomposites were investigated by in situ transmittance IR and reflection absorption IR spectroscopy, respectively. The results show that CNTs can enhance both the cold and melt crystallization rates of bulk PLLA, which is consistent with the common observation in the literature. However, it is interesting to find that the crystallization rate of PLLA thin film is suppressed by the addition of CNTs. Moreover, it is found that the existence of CNTs could not alter the preferred orientation of PLLA helical chain in the thin film. The different crystallization kinetics of PLLA induced by the addition of CNTs in bulk and thin film were explained by the confined crystallization behavior of polymer thin film.