Effect of Multiwalled Carbon Nanotubes on Crystallization Behavior of Poly(ε-caprolactone)diol

Multiwalled carbon nanotubes (MWNTs) were found to be well dispersed in poly(epsilon-caprolactone) diol (PCL) matrix after grafting to the surface of MWNTs by grafting to approach. Afterward, the effect of MWNTs on nonisothermal crystallization of PCL was investigated by differential scanning calorimetry (DSC), X-ray diffraction spectroscopy, and polarized optical microscopy (POM). From the DSC observation, the onset and peak crystallization temperatures of the composites were found to be always higher than those for neat PCL, indicating high nucleation ability of MWNTs in PCL. However, the crystallization rate, characterized by inversed half-crystallization time of the composite was lower than that of the neat PCL. The experimental data were analyzed using modified Avrami equation, and the activation energy for crystallization for PCL was found to reduce in the presence of MWNTs. POM showed a direct evidence for nucleating action of MWNTs in the crystallization process.