| Since 1960 s,the high performance advanced composite materials with carbon fiber as reinforcing materials have been widely used in many fields.More and more people are concerned about the low-cost manufacturing technology of advanced composite materials.At present,the RTM technology is developing rapidly,and one of the keys of RTM technology is to find the ideal resin system.Epoxy resin is usually used in the preparation of resin matrix composites.However,after curing the epoxy resin is brittle,and it has a high cross-linking density and a low impact strength,therefore it needs to be modified.In this paper,different toughening agents were selected to modify the epoxy resin.By examining the mechanical properties and thermal mechanical properties of the cured products,the suitable resin system was selected.The rheological properties of the optimized resin system were analyzed,the RTM process window was determined,and the carbon fiber reinforced composite materials were prepared,and the mechanical properties,thermal weight loss and thermal physical performance of the composite materials were discussed.In this paper,the epoxy resin system was modified with organosilicon core-shell particle,polysulfone and polyether amine,and the mechanical and thermal mechanical properties were tested.It was found that the addition of toughening agents had effectively improved the toughness of epoxy resin system.After the comprehensive analysis of the toughening effect of several kinds of toughening agents on the epoxy matrix,we had found that when the polysulfone with an addition amount of 5phr was used to modify epoxy resin system,the elongation at break was increased by 166%,and tensile?bending and impact strength were increased by 81.1%?25.6%?64.5% respectively.And the compatibility was excellent after mixing,the working life was long and the comprehensive performance was the best.Finally,it was confirmed that the polysulfone was selected as the toughening agent,and when the addition amount was 5phr,the toughening effect was the best.The curing reaction and chemical rheological features of epoxy resin system were studied.Based on the relationship between viscosity and temperature,viscosity and time of epoxy resin system,a double Arrhenius model which described the chemical rheological behavior of epoxy resin system was established.The studies showed that the simulation value and the experimental value of the rheological model of resin system had a good consistency.The model could accurately describe the chemical rheological behavior of epoxy resin system in the range of low viscosity,and it could forecast the process window in the RTM molding process.The modified epoxy resin system was used as matrix resin,the carbon fiber woven fabric was used as reinforced material,and 3 kinds of composite material had been prepared by RTM process which were toughening agent-free,ex-situ toughening and in-situ toughening materials respectively.Through the ultrasonic scanning,it was found that the three kinds of composites were basically uniform inside except the entrance.The tensile strength of ex-site toughening composite increased by 18.4% and 27.3% respectively compared with the in-situ toughening and blank samples,and the bending strength increased by 35.2% and 30.2% respectively.Compared with the blank sample,the layer shear strength of the in-situ and ex-situ toughening samples increased by 44.3% and 52.8% respectively.At 800 ?,the carbon residue rate of the blank sample,ex-situ toughening and in-situ toughening sample was 69.9%,79.5%and 73.1% respectively,which indicated that the heat resistance had improved significantly.The average water absorption rate of the three kinds of composite materials was very low,which was 0.15%,0.18% and 0.11% respectively.On the whole,the resin matrix composites prepared by RTM process have excellent comprehensive performance. |
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