Effect of a Novel Nucleating Agent on Isothermal Crystallization of Poly(L-lactic acid)

The effect of a novel active nucleating agent (TBC8-eb) on the isothermal crystallization of poly(L-lactic acid) (PLLA) was studied by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The analysis on kinetics demonstrates that TBC8-eb can not only accelerate the crystallization rate but also transform most of the original spherulite crystals of PLLA into sheaf-like crystals. Furthermore, the free energy of folding (sigma(e)) of PLLA and PLLA with TBC8-eb is 0.15 and 0.06 J.m(-2), respectively, which suggests that the addition of TBC8-eb favors the regular folding of molecule chains in the crystallization of PLLA, improving its crystallization rate. The FTIR results show that TBC8-eb can accelerate the conformational ordering of PLLA in the isothermal crystallization. The conformational ordering of PLLA nucleated with TBC8-eb begins with the interchain interaction of -CH3, and then a short helix emerges where a couple of -CH3 groups interact.