Formulation, characterisation, and development of cyanate ester high temperature nanocomposite polymer matrices for aerospace applications

Composite structures are seeing demands in applications requiring higher temperature performance, and thus there is a need for advanced resin systems designed to meet this requirement. Temperature profiles for materials used in gas turbine engines show the use of modified bismaleimide resins for temperatures up to 180 °C, above which polyimide resins are employed. This thesis is concerned with the development of novel phenolic-triazine (PT) resin blends, with particular emphasis being placed on enhancing the understanding of systems that exhibit high temperature stability (longevity), bridging the gap between bismaleimides and polyimides. The use of cyanate ester resins as baseline materials, combined with reactive diluents, cure initiators, and nanoadditives was employed, to produce high performance matrices with desirable thermal and mechanical properties, making them attractive to the aerospace industry. Newly developed blends were formulated, and their reactivity and processing characteristics were investigated. The use of thermal analysis equipment, such as differential scanning calorimetry (DSC) and rheology was employed to gain a better understanding of the thermal properties they demonstrate. Dynamic curing kinetics allowed a better understanding of the molecular dynamics involved prior to and during curing. To assess both the thermal and thermo-oxidative stability of the blends, thermogravimetric analysis was used under both anaerobic and aerobic environments. Further investigation referred to hydrolytic stability, as well as fracture toughness determination and hot/wet thermomechanical performance. The newly formulated blends exhibited: i) increased reactivity indicating lower curing temperatures and a smaller thermal jump, ii) better processability at reduced temperatures indicating ease of nanoadditive incorporation, and fibre wet out and resin degas for resin transfer moulding, as well as flexibility to be tailored for different manufacturing methods, iii) improved hydrolytic stability indicating improved hot/wet performance and reduced microcracking, iv) enhanced fracture toughness, as well as v) comparable thermal stability to the industrial standard and baseline material of the study, Primaset™ PT-30. A CFRP laminate was manufactured as proof of concept, that the resins can be infused and handled at lower temperatures than the baseline, and the desired properties are attained