The Crystallization of Polypropylene in Multiwall Carbon Nanotube-Based Composites
CONCLUSIONS
The analysis of the crystallization of iPP in its compo- sites with MWCNTs by differential scanning calorimetry, under both isothermal and dynamic conditions, has demon- strated that both the crystallization temperature of iPP obtained under dynamic conditions and the isothermal crys-tallization rate are affected by the presence of MWCNT, showing a significant increase in both parameters. This is composition dependent and confirms the existence of a nucleation effect on the crystallization of iPP due to the presence of MWCNT dispersed in the iPP melt. This nucle- ation phenomenon is manifested by a reduction in the val- ues of basal interfacial free energies for iPP, and a subse- quent reduction in the free energy of nucleation and an increase in the global crystallization rate, whilst maintain- ing the monoclinic crystalline structure of iPP. The pres- ence of MWCNTs only has a slight influence on the dou- ble-endothermic melting behavior of iPP, manifesting small but clear increments in the melting temperatures.