The Crystallization of Polypropylene in Multiwall Carbon Nanotube-Based Composites
The crystallization process of isotactic polypropylene (iPP) was studied under both dynamic and isothermal conditions for a series of multiwall carbon nanotube (MWCNT) composites with nanotube concentrations between 0.1 and 1.0% by weight. The nucleation activ- ity of the nanofillers was confirmed for both dynamic and isothermal crystallization, and was shown to be composition dependent. The effect of the nanofiller on the crystallization of iPP was discussed using the tem- perature coefficients obtained to determine the interfa- cial free energy and free energy of nucleation. The ba- sal interfacial free energy decreased with respect to that of neat iPP by up to 15% for as little as 0.1% MWCNT, subsequently decreasing linearly with increas- ing nanotube concentration. This behavior is in line with the crystallization behavior of iPP with conven- tional nucleating agents. POLYM. COMPOS., 32:324–333, 2011. a 2010 Society of Plastics Engineers