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℃ to 227℃,the nuclei density was increased,and the non-isothermal crystallization temperature(Tc)of PGA was increased from 156℃ to 197℃ and the half-life time(t0.5)of isothermal crystallization at 207℃ 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.