Nucleation and crystallization kinetics of polyamide 12 investigated by fast scanning calorimetry

Abstract

Nucleation and crystallization of polyamide 12 (PA 12) have been systematically investigated by fast scanning calorimetry at non-isothermal and isothermal conditions. The critical cooling rates of crystallization and crystal nucleation were determined as 300 and 10,000 K/s, respectively. Moreover, the half-times of nucleation (t1/2,nucl) and overall crystallization (t1/2,cry) show monomodal and bimodal dependencies on the crystallization temperature. t1/2,nucl has an approximate minimum value of about 0.0005 s at 333 K, which is about 10–20 K above the glass transition temperature, and t1/2,cry has two minima of about 0.05 and 0.8 s at about 333 and 383 K, respectively. Comparing the crystallization behavior of PA 12 with other polyamides, the activation energy for crystallization increases and the energy barrier of short-range diffusion decreases with the increase of the amide-group density in the chains.