Mechanism and Properties of Aromatic Amines Room Temperature Catalyzed Curing of Cyanate Ester and Epoxy Resin System

Abstract

The room‐temperature curing behavior of cyanate ester/epoxy resins in the presence of aromatic amines was comprehensively investigated by DSC and FTIR. Additionally, the curing mechanism was confirmed via PY‐GC‐MS. The results showed that in the reaction system, the catalyst not only promoted the formation of the triazine ring from the cyanate ester but also induced ring opening of the epoxy group. The ring‐opened epoxy group then reacted with either the cyanate ester group or the intermediates containing ─C─O═NH to generate oxazolidine. Subsequently, the oxazolidine underwent a rearrangement reaction, leading to the formation of oxazolidinone. After a 5‐day reaction at room temperature, the curing degree of the resin system reached 80.6%, thus accomplishing room temperature polymerization. For room‐temperature fast‐curing adhesive applications, this reaction system not only ensures a relatively short initial curing time but also guarantees a minimum sizing time of 60 min. When the epoxy resin content was 20%, the cured system exhibited a T_d5 (5% weight loss temperature) of 323 °C, a flexural strength of 71.43 MPa, and a tensile shear strength of 8.06 MPa, with vacuum volatility meets aerospace standards.