Mixed hyperbranched poly(aryl ether ketone) results in high toughness and excellent thermal resistance in epoxy resin

Epoxy resins are well used in many fields, but their problem of poor toughness restricts the further expansion of their applications. Facing this problem, this study successfully prepared high toughness epoxy resins using hydroxyl-terminated hyperbranched poly(aryl ether ketone) (HBPAEK-OH) as a toughening agent. Firstly, HBPAEK-OH was synthesized based on molecular structure design, combined with the optimized conditions of heat resistance and solubility. Then HBPAEK-OH was mixed with bisphenol A diglycidyl ether (DGEBA) to prepare a series of epoxy resins (HBP/DGEBA-n) with superior thermal properties, whose glass transition temperature (Tg) can reach 113.9 °C, which is about 38 °C higher than that of HBP/DGEBA-0. The tensile strength, flexural strength, impact strength, and elongation at break of HBP/DGEBA-n showed a tendency to increase and then decrease with the increase of HBPAEK-OH content, and the highest values reached 86.43 MPa, 128.50 MPa, 57.03 kJ/m2, and 7.15 %, respectively. Among them, the impact strength and elongation at break increased by 179.3 % and 87.2 %, indicating that the toughness of HBP/DGEBA-n was significantly improved. This study explores a new method for toughening epoxy resins, which improves their toughness and heat-resistant properties and provides new possibilities for their expansion in different applications.