A new epoxy resin (EPOSIR 725) suitable to manufacture structural aerospace componemts by resin transfer moulding (RTM) technology has been developed. The more significant features are: suitable physical and mechanical properties, in particular glass transition about 140 C, low shrinkage (0.28%); very low health risk (no toxic components in precursors or curing agents); suitable processability (low viscosity (300-400 cps at low temperature)) and useful curing cycles.
Based on this resin, the RTM process has been successfully implemented for the production of integral stiffened panels (having complex geometry) with good dimensional tolerance and good surface finish.
2 other interesting epoxy systems for RTM technology (EPOSIR 687 and 688) having reduced production cost have also been investigated. They will be useful in applications where low brittleness is not mandatory and which require short or medium curing cycles and (in the case of 687) a ratio of resin to hardener of about 1 to 1.