Crystallization kinetics, morphology, and hydrolytic degradation of novel biobased poly(butylene succinate-co-decamethylene succinate) copolyesters

In previous work, we synthesized three novel biodegradable poly(butylene succinate-co-decamethylene succinate) (PBDS) copolyesters with different decamethylene succinate (DS) compositions and studied their basic thermal behaviors, crystal structure, and mechanical properties (Polym. Degrad. Stab. 134 (2016) 305-310). In this work, the isothermal melt crystallization kinetics, spherulitic morphology and growth rates, and hydrolytic degradation of these PBDS copolyesters were further investigated and compared with those of their homopolymer poly(butylene succinate) (PBS). With increasing DS composition and crystallization temperature, the overall isothermal melt crystallization rates of PBDS decreased; however, the crystallization mechanism of PBDS and PBS remained unchanged. Spherulitic morphology and growth rates of PBDS and PBS were investigated in a wide range of crystallization temperatures. Increasing crystallization temperature and DS composition decreased growth rates of PBDS spherulites. Both PBDS and PBS exhibited a crystallization transition from regime II to regime III; moreover, the crystallization regime transition temperature shifted to lower temperature with increasing DS composition. The hydrolytic degradation rates of PBDS copolyesters gradually decreased with increasing DS composition. Scanning electron microscopy study demonstrated the surface erosion mechanism of the hydrolytic degradation of PBDS and PBS.