Tailoring the crystallization behavior and mechanical property of poly (glycolic acid) by self-nucleation

Biocompostable poly (glycolic acid) (PGA) crystallizes slowly under fast cooling condition, leading to poor mechanical performance of the final products. In this work, a self-nucleation (SN) route was carried out to promote the crystallization of PGA by regulating only the thermal procedure without any extra nucleating agents. When self-nucleation temperature (Ts) decreased from 250 oC to 227 oC, the nuclei density was increased, and the non-isothermal crystallization temperature (Tc) of PGA was increased from 156 oC to 197 oC and the half-life time (t0.5) of isothermal crystallization at 207 oC was decreased by 89%. Consequently, the tensile strength and the elongation at break of the PGA were increased by 12% and 189%, respectively. According to the change of Tc as a function of Ts, a three-stage temperature domain map (Domain I, II and III) was protracted and the viscoelastic behavior of the self-nucleation melt and the homogeneous melt was studied. The results indicated that interaction among PGA chains was remained in Domain IIb, which can act as pre-ordered structure to accelerate the overall crystallization rate. This work utilizes a simple and effective SN method to regulate the crystallization behavior and the mechanical properties of PGA, which may broaden the application range of resulting materials.