Crystallization behavior of polylactide nucleated by octamethylenedicarboxylic di(2-hydroxybenzohydrazide): Solubility influence

Abstract

The crystallization ability of polylactide (PLA) was improved by the addition of a hydrazide compound, octamethylenedicarboxylic di(2-hydroxybenzohydrazide) (OMBH). The nucleation efficiency of OMBH significantly depended on its solubility during annealing treatment. The solubility of OMBH increased gradually with increasing the final annealing temperature (Tf) and/or decreasing the addition concentration of OMBH (COMBH). At a certain COMBH (e.g. 0.5 wt%), the crystallization of OMBH shifted to a lower temperature with increasing Tf due to the increased OMBH solubility. This decreased the crystallization temperature, crystallization enthalpy, and isothermal crystallization rate of PLA. Additionally, at a certain Tf (e.g. 200 °C), the crystallization temperature and nucleation efficiency of OMBH increased with its concentration, resulting in the increase of crystallization temperature, crystallization enthalpy, and isothermal crystallization rate of PLA.