“Nucleation density reduction” effect of biodegradable cellulose acetate butyrate on the crystallization of poly(lactic acid)

Both poly(lactic acid) (PLA) and cellulose acetate butyrate (CAB) are bio-based and biodegradable. In this work, the effect of CAB on the cold and melt crystallization behavior of PLA was investigated by differential scanning calorimetry and polarized optical microscopy. Both the cold and melt crystallization of PLA was dramatically inhibited even at a very low loading of 0.5 wt% CAB. The isothermal crystallization kinetics was analyzed by the Avrami model. It was found that the Avrami exponent of PLA crystallization was not significantly influenced by the addition of CAB, indicating that the crystallization mechanism of PLA almost did not change in the blends. The crystallization half-time of the blends increased significantly with increasing CAB loading. The observation from optical microscopy further revealed that the presence of CAB reduced remarkably the nuclei density but had nearly no influence on the spherulite growth rate of PLA. These observations indicate that CAB has dramatic “nucleation density reduction” effect on PLA.