Crystallization behaviors of poly(lactic acid) composites fabricated using functionalized eggshell powder and poly(ethylene glycol)

The eggshell power decorated with calcium phenyphosphonate (NES), an effective nucleating agent for poly(lactic acid) (PLA), was introduced into PLA simultaneously with a plasticizer, poly(ethylene glycol) (PEG), via melt blending. The morphology and melt crystallization behaviors of PLA composites were studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). PEG improved compatibility and interfacial adhesion between NES and PLA, which made NES dispersed more evenly in PLA matrix. The isothermal melt crystallization rate of PLA/PEG/NES was fastest in all the composites, indicative of a synergistic effect between PEG and NES. For the nonisothermal melt crystallization, the Avrami and Mo's model could describe the experiment data successfully. Whereas the Ozawa equation failed to provide an adequate description for the composites. Moreover, the crystallization activation energy was further evaluated based on Friedman equation.