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Epoxy These are available in many different forms and can be processed using numerous techniques, such as wet lay up, vacuum oven/autoclave, press moulding, resin transfer moulding, filament winding and pultrusion. They have excellent mechanical properties, good environmental resistance and high toughness. They can be formulated to suit many applications providing characteristics such as high service temperature, impact resistance, improved hot/wet mechanical performance, and fire retardancy. Phenolic This type of resin system is most commonly used where fire resistance/prevention/low smoke & toxicity outweigh all other criteria (e.g. aircraft interior panels). It has excellent fire resistance, and is relatively cheap. It can be difficult to process with some acid catalysed variants attacking composite tool surfaces. Compared to epoxy systems they have very low mechanical properties. Bismaleimide These are relatively expensive systems but they have excellent mechanical properties at elevated service temperatures. They can prove to be difficult to process due to the high cure temperatures required and the low viscosity that occurs under cure conditions. Cyanate Ester Cyanate ester resins have the capability to retain their mechanical properties at extremely high service temperatures (up to 350°C), however they are also expensive. They can absorb water which can give rise to problems with blistering. Processing is similar to epoxies. |