Controllable preparation of a novel epoxy/anhydride system with polyether - Polyester semi-interpenetrating structure and the excellent hydrothermal aging resistance properties

A novel polyether and polyester semi-interpenetrating cross-linking structure of epoxy/anhydride system catalyzed synergistically by anionic catalyst and coordination catalyst was designed and prepared to solve the hygrothermal aging problem of traditional epoxy/anhydride systems. The new network structure was obtained from an epoxy/anhydride with molar ratio of 1.4:1.0 via a series of esterification reaction of epoxy and anhydride copolymerization as well as etherification reaction of epoxy self-polymerization by a composite catalyst of Salen-Co and BDMA. In the semi-interpenetrating cross-linking networks, the polyether chains, with its low polarity, multiple sterically hindered effect and strong hydrolysis resistance, could effectively protect the polyester chains from water molecule attack and vastly improved the hygrothermal aging resistance of the epoxy/anhydride system. As a result, the cured epoxy/anhydride resin had excellent hydrothermal aging resistance properties, the reductions in the glass transition temperatures of samples aging in NaCl and NaOH solutions at 60 °C for 28 days were only 2.9% and 3.9%, while the flexural strength retentions were up to 93.3% and 88.4%. The novel epoxy/anhydride with semi-interpenetrating cross-linking structure of polyether and polyester exhibited application preponderance in large ship and offshore fan blade composites preparation.