Abstract:
The crystallization kinetics of polyamide 11 (PA 11) in presence of sepiolite and organomodified
montmorillonite nanofillers has been studied in a wide range of temperatures and
cooling rates by conventional differential scanning calorimetry (DSC) and fast scanning
chip calorimetry (FSC). The presence of the nanofillers has a negligible effect on the
crystallization temperature of PA 11 at low cooling rates. However, at rapid cooling
conditions a distinct nucleating effect of the nanofillers is detected. The critical cooling
rate to suppress crystallization increases from 600 K s–1 to about 1000 and 3000 K s–1 in
nanocomposites containing sepiolite and montmorillonite, respectively. Regardless the
cooling rate applied for solidification the melt, in the nanocomposites the crystallinity of
PA 11 is 5 to 10 % higher than in neat PA 11, with the highest values obtained for the
montmorillonite-containing system. The nucleating effect of the nanofillers onto the
crystallization of the PA 11 is confirmed by analysis of the half-times of isothermal
crystallization, and by analysis of the spherulitic superstructure. All measurements proved
a saturation of the nucleation efficiency at a loading of the nanofiller of 2.5 m%.
