Studies On The Resin Films For Composite Components Fabricated By RFI

Resin Film Infusion (RFI) has been an attractive process for fabricating large, complex and rib-stiffened composite components, however the RFI process requires special performances of the resin system, and this greatly limits the application of the process. A hybrid resin system with epoxy resins is proposed and studied in this paper.According to the requirements of RFI and the properties of the composite components, three types of epoxy resins, namely, E-44, E-31 and E-21 respectively, and four intermediate-temperature curing agents with long shelf lives, i.e. imidazole 704, acid anhydrides SK-570 and WTZ-3200, and modified aromatic amine GA-327 respectively, were chosen in the study. The curing system, which consists the hybrid epoxy resin of E-44 and E-21 with ratio of 6:4 by weight, and curing agent GA-327(40phr), offers the resin film better film-forming ability and longer shelf life than the other curing systems do. The hybrid resin film satisfies the requirement of the composite components fabricated by RFI.The Z average molecular weight, the weight average molecular weight and the number average molecular weight of the hybrid resin is 3062, 940 and 153 respectively, and the epoxy value is in the range of 0.32 to 0.37. The viscosity-time character of the hybrid resin shows that it is suitable to infuse at 75~80℃. The microscale fracture morphology of the hybrid resin casting samples indicate that a hybrid fracture mode is observed, and this is due to the improvement of flexibility of E-21 with the addition of E-44. The cured hybrid epoxy resin exhibits excellent waterproof, and the saturated water absorption reaches 0.132% at room temperature, while 0.208% in boiling water. The tensile strength of the resin film with the elongation rate at rupture of 450% is 33kPa, and the vertical tearing strength of the resin film is up to 33kPa.