Reactive Toughening of Poly(Glycolic Acid)/Poly(ε‐Caprolactone) Blends Using Environmentally Friendly and Cost‐Effective Bio‐Based Chain Extenders

ABSTRACT The widespread distribution of microplastics has spurred urgent demand for biodegradable polymer alternatives. As a biocompatible and biodegradable aliphatic polyester, the development of poly(glycolic acid) (PGA) has been limited by its inherent brittleness. Reactive blending with a flexible polymer is an effective method to improve its properties, but most chain extenders are expensive, difficult to degrade, and some even exhibit biotoxicity. An eco‐friendly compatibilizer system (denoted as TE), composed of biomass‐derived tannic acid (TA) and epoxidized soybean oil (ESO), was introduced to regulate the miscibility of poly(ε‐caprolactone) (PCL) in the PGA matrix. TE improved the compatibility of polyesters, expanded the processing temperature window, enhanced melt strength through in situ crosslinking reactions, and enabled PCL to fully exert its toughening effect. When 1–5 wt% TE was added to the PGA/PCL‐90/10 blend, the elongation at break was increased to 117.6%–149.8%, which was about 2040%–2620% higher than that of pure PGA (5.5%), and the hydrolysis rate was reduced by 22%–25%. Considering that the cost of the composite chain extender is much lower than that of commercial chain extenders, this work presents an environmentally friendly and economical option for the industrial‐scale production of high‐performance PGA composites.