The effect of well-dispersed nanoclay on isothermal and non-isothermal crystallization kinetics of PHB/LDPE blends

The crystallization kinetics of PHB/LDPE blends and their nanocomposites containing different LDPE and organoclay loadings was investigated using DSC. Nanoclay localization in the PHB phase was determined by XRD and confirmed by rheological measurements and TEM. The rate and other kinetic parameters for crystallization were investigated using theoretical models, such as Avrami, Liu–Mo and Friedman. The effect of nanoclay on the first stage of crystallization was explored, based on Dubreva's nucleation activity analysis. The Friedman model results showed that incorporation of either nanoclay or LDPE would increase the PHB activation energy of crystallization through two different mechanisms, namely increasing the viscosity and nuclei migration, respectively. Interestingly, the activation energy of PHB/LDPE nanocomposites was not as high as that of PHB/LDPE binary blends. This finding was also observed in isothermal and non-isothermal kinetics studies and could be explained by nuclei transfer from the PHB phase to the melt phase. According to Avrami exponent values, neither Cloisite 10A nor LDPE changed the nucleation mechanism of PHB. Incoroporation of LDPE successfully reduces rigid amorphous amount.