Crystallization kinetics of polyamide 11 in the presence of sepiolite and montmorillonite nanofillers

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%.