Miscibility And Crystallization Behaviors Of Two Poly (Butylene Succinate) Copolyesters Based Polymer Blends

Two miscible crystalline/amorphous polymer blends were prepared by solution casting method. Differential scanning calorimetry (DSC), polarizing optical microscope(POM)and wide-angle X-ray diffraction(WAXD)were employed to investigate the miscibility and crystallization behaviors of the blends.1. Miscibility and crystallization behaviors of poly(butylene succinate-co-butylene terephthalate) (PBST)/poly(hydroxyl ether biphenyl A) (phenoxy) blends.PBST/phenoxy blends were prepared through solution casting method using chloroform (CHC13) as a mutual solvent. The DSC results show that PBST and phenoxy are completely miscible as evidenced by the single composition dependent glass transition temperature (Tg) over the entire blend compositions. Nonisothermal melt crystallization peak temperature and crystallization enthalpy are higher in neat PBST than in the blends at a given cooling rate. Isothermal melt crystallization kinetics of neat and blended PBST was studied and analyzed by the Avrami equation. The overall crystallization rate of PBST decreases with increasing crystallization temperature and the phenoxy content in the PBST/phenoxy blends; however, the crystallization mechanism of PBST does not change. Moreover, the WAXD results indicate that blending with phenoxy does not modify the crystal structure but reduces the crystallinity of PBST in the PBST/phenoxy blends.2. Miscibility and crystallization behaviors of poly(butylene succinate-co-butylene adipate) (PBSA)/tannic acid(TA)blendsCompletely biodegradable PBSA/TA blends were prepared through solution casting method using p-dioxane as a mutual solvent. PBSA and TA are completely miscible as evidenced by the single composition dependent Tg over the entire blend compositions. Nonisothermal melt crystallization peak temperature and crystallization enthalpy are higher in neat PBSA than in the blends at a given cooling rate, indicating that the crystallization of PBSA was hindered by the addition of the amorphous TA. Isothermal melt crystallization kinetics of neat and blended PBSA was studied and analyzed by the Avrami equation. At the chosen crystallization temperatures, the overall crystallization rate of PBSA decreases with increasing crystallization temperature and the TA content in the PBSA/TA blends; however, the crystallization mechanism of PBSA does not change. The POM results indicate that the nucleation density of PBSA was reduced by the addition of TA. Moreover, blending with TA does not modify the crystal structure of PBSA in the PBSA/TA blends.