Crystallization Kinetics Study of Poly(L-lactic acid)/Carbon Nanotubes Nanocomposites

Effects of carbon nanotubes (CNT) on the isothermal crystallization kinetics of poly(L-lactic acid) (PLLA) were quantitatively investigated using the Avrami equation and the secondary nucleation theory of Lauritzen and Hoffman. CNT via grafting modification with PLLA could well disperse in the PLLA matrix and give significantly enhanced crystallization rate and crystallinity of PLLA as analyzed by differential scanning calorimetry and polarized optical microscopy. Analysis of isothermal crystallization kinetics using the Avrami equation demonstrated that CNT significantly enhanced the bulk crystallization of PLLA. Analysis of spherulite growth kinetics using the secondary nucleation theory of Lauritzen and Hoffman found that CNT could expand the temperature range of the crystallization regime III of PLLA. Values of the nucleation constant (K(g)) in crystallization regimes III and II of PLLA both increased with increasing CNT contents. The K(g) III/K(g) II ratios were found to be close to the theoretical value 2 hut were not clearly found to depend on the CNT contents. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 983-989, 2010