Study On Resin Flowing Behavior And Impregnationin In Out-og-autoclave Prepreg

As a model for low-cost composite manufacturing technology,out-of-autoclave(OOA)prepreg is favored by aerospace and industrial applications.OOA prepreg is usually designed to be partially submerged forms which contain dry fibers and resin-rich zones.The dry fibers,the function of which is vacuum exhaust passages,are impregnated with resin during the curing.Therefore,the study of curing dynamics,rheology and infiltration dynamics of OOA prepreg resin system is much helpful for the forming process.In this paper,by studying the curing kinetics,rheology and gel behavior of the system,the curing agent and epoxy resin matrix of OOA prepreg resin system were selected.The infiltration flow model of the resin system was established to realize the optimization and quality control of the composite material forming process.1.Preparation of dicyandiamide(DICY),polyether amine/icyandiamide(PEA/DICY)and liquefied dicyandiamide(L-DICY)curing system prepreg resin system.The curing behavior of the three resin systems was studied by using the curing kinetics equation,the gel model and the Dibenedetto equation.Then the time-temperature-transition(TTT)plot of the resin system was plotted and the processing conditions of the system was determined.From the perspective of optimizing the process conditions,the L-DICY system was selected as the resin system for the OOA prepreg.2.The prepreg resin system was prepared by using bisphenol-A epoxy resin(EP)and intrinsic flexible epoxy resin(IFEP)and liquefied dicyandiamide(L-DICY)respectively.This paper also studied the rheology of the resin,fit the rheological equation,and then built the time-temperature-transition-viscosity(TTT-η graph.The IFEP/L-DICY resin system was more suitable for the preparation of OOA prepreg by comparing the Tg,gel and the corresponding time of the two systems.On the basis of TTT-η)graph,the preparation conditions and forming conditions of OOA prepreg were determined.3.The OOA prepreg was prepared by IFEP/L-DICY resin system.The resin system infiltration model was established by determining the parameters such as fiber volume fraction,fiber radius,fabric permeability,viscosity and boundary conditions.The porosity of the resin was investigated by studying the wetting behavior of the resin on the fiber during the warming and constant temperature curing of the OOA prepreg.The validation of the infiltration model shows that the experimental values are in good agreement with the model values.The performance of OOA and hot press composites is evaluated.The results show that the performance retention rate of OOA composites is more than 80%,which indicates that the optimized process conditions can effectively improve the performance of OOA composites.