Controlling the size of spherulite and the degradation of poly(butylene succinate-co-adipate) by solvent and gel preparation temperature

The size of spherulites observed in the poly(butylene succinate-co-adipate) (PBSA) gel was found to be effectively controlled by the careful selection of the types of solvent and the gel preparation temperature. Additionally, the degradation behavior of the PBSA dried-gels with different sizes of spherulites was studied. By using different solvents, such as toluene (TOL), o-dichlorobenzene (o-DCB), and cyclohexanone (CHN), the diameter of the spherulites could be changed from 16.7 μm to 186.2 μm, while the gel preparation temperature was kept constant at 28 °C. The gel preparation temperature was then changed from −50 °C to 28 °C using CHN, and it was found that the diameter of the spherulites changed from 25.2 μm to 186.2 μm. Regarding the degradation behavior, the PBSA dried-gel with relatively smaller spherulites (∼20 μm in diameter) exhibited higher weight loss of over 80% at the immersion time of 6 days, while the PBSA dried-gels with relatively larger spherulites (∼186 μm in diameter) presented lower weight loss of below 30% at the immersion time of 6 days. It was therefore concluded that the degradation rate became lower with the increase in the size of spherulites.