| Resin transfer molding(RTM) is a low cost, high efficiency production technology of the composite material which was introduced into China in the 80’s. Its design ability is strong. It can be combined with fiber weaving and preforming technology to make complex shape parts. Products’ dimensional accuracy and surface finish is high. Mold manufacturing and material selection maneuverability is strong. It is easy to realize local enhancement of model artifacts and pipe without the heavy labor intensity of manual layer and vacuum bag molding process. Transportation and storage of frozen presoak materia doesn’t need, neither. Good working environment, low energy consumption, strong adaptability are all RTM’s advantage.Preparation of RTM process as a whole structure of cryogenic composites obtained the widespread application with the deepening of the research in the fields such as aerospace, aviation.When choosing resin for low temperature system, on the one hand, we need to meet the requirements of RTM process for resin system(low viscosity, moderate activity);On the other hand, casting body breaking elongation rate need to be high, keep good toughness at low temperature, high tensile strength and heat resistance, keep good strength and modulus in room temperature or higher temperature.There exists contradiction between the two aspects that one party will weak the other’s advantages.In order to solve the above problems, this research has carried out the following work:(1)The preparation and properties of phenolic aldehyde amine curing agent: with isophorone diamine(IPDA), polyether amine(D230), diamino diphenyl methane(DDM) three amine curing agent as the main raw material, through mannich modification, get serialized phenolic aldehyde amine curing agent M- IPDA, M- D230, M- DDM. The molecular structure of the three kinds of phenolic aldehyde amine curing agent was characterized by infrared spectral; The different curing system of dynamic curing active was compared by DSC curve. IPDA, M- IPDA, D230, M- D230, DDM, M- DDM’s largest temperature curing Tp are: 109.4 ℃, 84.8 ℃, 125.3 ℃ and 96.5 ℃, 160.6 ℃ and 121.5 ℃; of The cured stability was analyzed by research the stability of thermal properties. Glass transition temperature Tg of IPDA, M- IPDA, D230, M- D230, DDM, M- the DDM respectively: 123.2 ℃, 82.3 ℃, 77.3 ℃ and 56.4 ℃, 141.2 ℃ and 88.8 ℃;Through mechanical properties compared the different curing of toughness, IPDA, M- IPDA, D230, M-D230, DDM, M- the impact strength of epoxy curing DDM(k J/m2) is respectively 95, 110, 116.2, 123.9, 67.2, 82.Results showed that the activity of the modified amine curing agent is higher than the corresponding amine, viscosity is lower, toughness is increased. The M- D230 have the lowest viscosity, moderate activity, best toughness.(2)Preparation and characterization of liquid aromatic amine ZZL: with ethyl aniline, hydrochloric acid and aniline as raw material, we prepared liquid DDM, MEDDM and DEDDM ternary mixtures, namely ZZL liquid aromatic amine curing agent, through infrared spectral characterization of the molecular structure of the liquid aromatic amine.(3)–C-N-flexible chain structure and imidazole client base in preparation and characterization of hyperbranched curing agent: with trimethylolpropane, neopentyl glycol, triethanolamine, imidazole acrylic adduct with diethanolamine amidation products as the core, ethanolamine acrylic adduct in core elements on the basis of polycondensation reaction hydroxyl-terminated hyperbranched polyester, imidazole acrylic adduct with hydroxyl-terminated hyperbranched polyester reaction- C- N- flexible side chain structure imidazole hyperbranched polyester. Through infrared spectral characterization of the molecular structure of the hyperbranched curing agent, shows that the preparation of hyperbranched curing agent in accordance with the design of the molecular structure of curing agent.(4)The preparation and performance of RTM curing system: the phenolic aldehyde amine curing agent M- D230, liquid ZZL, and a series of hyperbranched aromatic amine curing agent of HBP-IM according to the quality than 2:6:2 compound got MCA-1, MCA-2, MCA-3,MCA- 4, four kinds of RTM process curing agent for epoxy resin system. Distribution of the four kinds of curing agents with bisphenol F epoxy resin according to the quality 33:100 to mix, comparing curing activity and curing of the thermal and mechanical properties. Through active contrast, four different curing system of curing time from short to long: MCA-1, MCA- 3, MCA-4, MCA-2;By MCA/epoxy resin curing of Tan delta temperature graph, we can see, glass transition temperature Tg of cured epoxy resin MCA-1, MCA-2, MCA-3, MCA-4 respectively is 127℃, 146℃, 146℃, 116℃;By dynamic mechanical curing epoxy curing system of DSC curve, we can see, MCA-1,MCA-2, MCA-3, MCA-4, the temperature of Tp at maximum curing speed, respectively: 133℃, 153℃, 140℃ and 158℃.It can be concluded that RTM curing agent MCA- 3 epoxy resin curing material properties and the thermal properties are the optimal, MCA- 3/epoxy resin curing system viscosity curve can be seen in 55℃, viscosity less than 1000 m Pa?s within 2h.It owns 2h of RTM process operation window.The innovation of this study lies in:This study overcomes the problem that traditional epoxy resin curing system cannot meet the requirements of RTM process and curing products with high strength and high toughness requirements at the same time, through to compound the homemade three kinds of curing agent(liquid ZZL, M- D230, hyperbranched aromatic amine curing agent HBP- IM series) to obtain MCA curing agent for epoxy resin RTM system. The curing product on the strength and toughness are better than imported isophoronediamine curing agent which has great potential application in aerospace materials. |
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