Novel heat-resistant and tough cyanate ester resin matrix for carbon fiber composite via wet winding process molding at a reduced temperature

Cyanate ester (CE) resin serves as an optimal matrix for CF composites owing to its exceptional heat resistance, mechanical properties, and interface adhesion. Nevertheless, addressing its inherent brittleness and high curing and molding temperature remains imperative. In this study, a sulfhydryl compound (MS) was employed as a free radical initiator for facilitating the co-curing or self-curing cross-linking reactions of CE and diallyl bisphenol A (DBA), which served as a toughening agent. The MS-DBA(15 wt%)-CE resin system had a low viscosity range of 300.0–800.0 mPa·s for long service time of over 140 min at 70–80 °C and was rapidly cured and molded at 155 °C. It served as an effective molding window for the wet winding of CF composites. Compared with the conventional non-catalytic pure CE resin cured at 270 °C, the MS-DBA(15 wt%)-CE resin was cured at 155 °C and had higher tensile strength, flexural strength, and non-gap-free impact toughness of 71.3 MPa, 159.8 MPa, and 13.2 kJ/m 2 , respectively. The glass transition temperature was kept high at 232.9 °C. MS-DBA reduced the molding temperature and formed toughening a cross-linking structure without losing the heat resistance. The CE/CF composite molded at 155 °C shows great potential for rocket engine shell materials. Highlights MS-DBA-CE has an excellent process window for CF wet winding molding. MS-DBA lowers curing temperature and toughens CE without losing thermal property. MS-DBA-CE/CF molded at 155 °C has high flexural strength at 150 and 230 °C.