Effect of temperatures on stress-induced structural evolution and mechanical behaviors of polyglycolic acid/polycaprolactone blends

Polyglycolic acid (PGA) is a high-strength polyester with good seawater degradability and biodegradability, which has good application prospects in packaging, but the poor toughness limits its wide use. The strength and toughness of PGA were simultaneously improved at high pre-stretch rates (300 mm/min) using extrusion-casting-thermal stretching with biodegradable polycaprolactone (PCL) as toughening agents. The effects of low, medium and high (close to the melting point of PCL) pre-stretching temperatures (Tp) on the aggregation structure and properties of the PGA/PCL blends were systematically elucidated. High Tp (63 °C) can promote the crystallization of PGA and increase the glass transition temperature, but the molecular chain relaxation rate is fast, resulting in high yield strength and low toughness of the blends. Molecular chain orientation is higher at low Tp (45 °C), but crystallinity is lower, resulting in high tensile strength (>150 MPa) and elongation at break (>110%) of the blends. The crystallinity of the blends is moderate and the orientation is lowest at medium Tp. Therefore, this work provides a simple and efficient method to prepare high strength and toughness of PGA materials, which is expected to expand the application fields of PGA-based materials.