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

Abstract

The crystallization kinetics of polyamide 11 (PA 11) in the presence of sepiolite and organo-modified 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 of the cooling rate applied for solidification of the melt, in the nanocomposites the crystallinity of PA 11 is 5–10 % 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%.