Drawing Temperature-Dependent Mechanical Properties of Poly(glycolic acid)/Poly(butylene adipate-co-terephthalate) Films

The application of biocompostable poly(glycolic acid) (PGA) is hindered by the conflict between its strength and ductility. In this work, we address an effective strategy to obtain designable strength and ductility of PGA/poly(butylene adipate-co-terephthalate) (PBAT) films by tuning the drawing temperature. At low temperatures (35-40 degrees C), the poor chain mobility leads to a predominance of stress-induced amorphous chain orientation rather than relaxation and crystallization, and the drawn films exhibit high tensile strength (145 MPa) with remarkable strain hardening. Then, the chain relaxation becomes pronounced due to the increased chain mobility at a temperature range of 45-50 degrees C, resulting in a low orientation, low crystallinity, and consequently high ductility (elongation at break of 320%). At the high temperature region (55-60 degrees C), further enhanced chain mobility facilitates the formation of oriented PGA crystallites, which restrict chain relaxation and provide more strengthened elements. As a result, PGA-based films with excellent strength, stiffness, and ductility (e.g., 103 MPa, 2800 MPa, and 220%, respectively) are achieved. Therefore, this work provides an effective route to tune the mechanical properties of PGA materials, and in principle it should be applicable to other semicrystalline polymeric systems as well.

Automated summary

This work successfully obtains designable strength and ductility of PGA/PBAT films by tuning the drawing temperature. The films exhibit high tensile strength and remarkable strain hardening at low temperature, high ductility at moderate temperature, and excellent strength, stiffness, and ductility at high temperature.