Material Characterization of Cyanate Ester Material for Structures with High Dimensional Stability Requirements

The degradation temperature, cure kinetics, viscosity, shrinkage, thermal expansion, and the modulus of RS-36-1 (modified epoxy), RS-3C and RS-3 (cyanate esters) are measured to evaluate the dimensional stability of these materials. L-shape carbon fibre-reinforced laminates with these polymer matrices are manufactured using Out-of-Autoclave (OoA) Vacuum Bag Only (VBO) processing and the spring-in angle is measured. Upon heating, cyanate ester resins experience expansion followed by shrinkage, which brings the overall shrinkage close to zero. Their coefficient of thermal expansion is found to be lower in comparison to the epoxy material, showing the lowest amount of spring-in. Finite Element simulation using COMPRO CCA is performed and the results are compared to the measurements performed on L-shape laminates. The methodology described herein shows phenomenological insight on the cyanate ester materials and the possibility to predict the effect of residual stresses during processing of composite parts, demonstrating high dimensional stability of cyanate esters.