A DSC study of the crystallization behaviour of polylactic acid and its nanocomposites

The isothermal crystallization behaviour of polylactic acid (PLA) and a clay nanocomposite of have been examined using differential scanning calorimetry. The data obtained clearly indicates that the presence of the nanocomposite particles in the composite material influences the crystallization kinetics of the PLA when crystallized both from the solid amorphous state as well as from the melt. When crystallized from the melt the presence of the clay nano-particles appears to be influencing the nucleation and crystal growth rate of the PLA such that the crystallization rate is enhanced by a factor of about 15 to 20. This result is of tremendous significance in identifying the processing window for the production of foamed nanocomposites from PLA. In addition the effect of thermal exposure at 200 degrees C on the crystallization behaviour of these materials has been investigated, with the results suggesting that holding these materials at 200 degrees C for periods of time up to 60 min in an inert atmosphere only has a marginal effect.