Isothermal Crystallization Kinetics of Poly(lactic acid)/Synthetic Mica Nanocomposites

The isothermal crystallization kinetics of PLA/fluoromica nanocomposites was studied. Three types of synthetic mica at three concentrations (2.5, 5.0, and 7.5 wt % mica) were used and the effect of these micas on the crystallization and thermal properties of PLA was investigated by differential scanning calorimetry (DSC). The Avrami and Hoffman-Weeks equations were used to describe the isothermal crystallization kinetics and melting behavior. Addition of these micas to the PLA matrix increased the crystallization rate, and this effect depended on the mica type and concentration. While the nonmodified Somasif ME-100 exerted the smallest effect, the effect observed for the organically modified Somasif MPE was the most pronounced. The lower half-time of crystallization t(1/2) was around 3 min for the PLA/Somasif MPE nanocomposites containing 7.5 wt % of filler at 90 degrees C, which is about 16 min below that found for neat PLA. The equilibrium melting temperature (T degrees(m)) of PLA were estimated for these systems, showing an increase in the composites and an increase with increasing loading, except for PLA/Somasif MPE, in which the increase of the mica content decreased T degrees(m) about 5 degrees C. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40322.