Effect of cellulose nanocrystals on crystallization, morphology and phase transition of polyamide 6

Nanocomposites comprised of polyamide 6 (PA6) and cellulose nanocrystals (CNC) were prepared by solvent casting and subsequent melt pressing. The role of cellulose nanocrystals on morphology, crystallization and conformation of the resulting PA6 nanocomposites were investigated using differential scanning calorimetry, thermogravimetric analysis and Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopic observation showed that the CNC were homogenously dispersed in the PA6 nanocomposites up to 5 wt% CNC. The thermal stability of the PA6 nanocomposites slightly decreased with the CNC loading. The addition of the CNC modified the non-isothermal crystallization behavior of the PA6 nanocomposites by increasing the crystallization temperature and the rate of nucleation. FTIR spectroscopic observation showed that the neat PA6 primarily crystallized in the more stable alpha crystalline form and that an alpha to metastable gamma crystalline transformation occurred with increasing concentrations of the CNC in the PA6 matrix. The non-isothermal crystallization kinetics of these nanocomposites with increasing CNC content were investigated, and it was demonstrated that the amount of CNC plays a significant role in crystallization kinetics.