Liquid Processable, Thermally Stable, Hydrophobic Phenolic Triazine Resins for Advanced Composite Applications

Composite structures are seeing demand for higher temperature performance and thus there is a need for advanced resin systems to meet this requirement. Here a commercial phenolic-triazine (PT) resin is combined with a blend of low viscosity difunctional cyanate ester (PrimasetTM LECy) to achieve a series of reactive binary systems. Throughout this work, the properties of the blends are compared against an industrial standard (PrimasetTM PT-30). The thermomechanical performances of the cured blends compare favourably with the industrial standard system with the best performing systems exhibiting Tg values in excess of 300 °C, based on the drop in storage modulus (compared with a value of at least 350 °C for PT-30). After conditioning for 3127 hours at 80 °C and 85% RH, a cured binary resin blend absorbed 4.9 wt% of moisture, compared with a figure of 5.2 wt % for PT-30. When exposed to 250 ºC in air continuously over a period of 3048 hours, the best performing of the binary cured blends lose only 48.3 % of their mass, compared with 45.0 % for PT-30 under the same conditions. The importance of this work is that the newly proposed resin blends containing 20 to 25 wt% LECy exhibit low viscosities (<1000 mPa.s) at 50 °C and are considerably more suitable for liquid composite moulding processes when compared with the state-of-the-art commercial matrix, while showing improved moisture performance, with only minimal loss in thermal performance.