Miscibility And Crystallization Behavior Of Two Biodegradable Polymers/Tannic Acid Blends

With the increasely shortage of oil resources and severe environmental problems caused by plastic waste, biodegradable polymers have received more and more attention. However, the application of the biodegradable polymers has been badly limited because of the relatively higher price, poorer mechanical properties and narrower processing window. Therefore, the modificaition of industrial biodegradable polymer is a meaningful project and of great importance.The polymer blending with solution casting method was employed in this work. Miscibility, crystallization kinetics, crystal structure, spherulitic morphology and growth rates of both poly(e-caprolactone) (PCL)/tannic acid (TA) blends and poly(ethylene succinate) (PES)/tannic acid (TA) blends were studied by differential scanning calorimetry (DSC), polarized-light optical microscopy (POM), and wide angle X-ray diffraction (WAXD), respectively. The results indicate that PCL and TA are miscible as evidenced by the single composition dependent glass transition temperature over the whole composition range and the depression of the equilibrium melting point of PCL in the PCL/TA blends. Isothermal crystallization kinetics of PCL/TA blends was investigated and analyzed by the Avrami equation. The overall crystallization rates of PCL decrease with increasing crystallization temperature and the TA content in the PCL/TA blends. Furthermore, the spherulitic morphology of PCL changed from dendritic spherulites for neat PCL to banded spherulites for the 80/20 blend. However, the crystallization mechanism and the crystal structure of PCL does not change in the blends after blended with TA content.Meantime, the PES and TA are also miscible as evidenced by the single composition dependent glass transition temperature and the depression of the equilibrium melting point of PES in the PES/TA blends. The overall crystallization rates of PES decrease with increasing crystallization temperature and the TA content in the PES/TA blends. Furthermore, the spherulitic size of PES is larger and the density is smaller. However, the crystallization mechanism and the crystal structure of PES do not change after blended with TA content.