Nucleation Effects of Nucleobases on the Crystallization Kinetics of Poly(L-lactide)

The effects of nucleobases, especially uracil, on the nonisothermal and isothermal crystallization, melting behavior, spherulite morphology, and crystalline structure of bio-based and biodegradable PLLA are studied. The melt- and cold-crystallization rates of PLLA increase with increasing uracil loading. The melting behavior of nonisothermally melt- and cold-crystallized PLLAs depends on the uracil content. The isothermal crystallization kinetics is analyzed based on an Avrami model. The incorporation of uracil changes the t1/2/Tc profile of PLLA due to the more distinct heterogeneous nucleation effects at small supercooling. The crystalline structure of PLLA is not affected by uracil presence. The nucleation density increases and the spherulite size decreases by uracil incorporation.