| Carbon fiber liquid composite molding (LCM) is molding process for large composite parts that develop rapidly in recent years. The key in molding process is that the resin cured after long-term seepage and wet with fibers. Therefore, the process requires the epoxy resin system with good liquidity, low heat and good wettability. While carbon fiber has low surface activity and poor wettability, so the research for the matching performance between epoxy resins and carbon fibers can provide a theoretical basis for the design and preparation of LCM technology matrix resin.In this paper, we used bisphenol F epoxy resin as the main resin, methylhexahydrophthalic anhydride as the curing agent,three different epoxy reactive diluents:1,4-butanediol diglycidyl ether (BDDGE), polyethylene glycol diglycidyl ether (PEGDGE), polyoxyethylene ethers of bisphenol A06(BPE-06) and prepared a low-viscosity epoxy resin system suitable for LCM process, then we explored the curing process and studied the matching performance with domestic carbon fibers (HF10), the concrete research are as follows.We studied how the structure of diluents, the dosage of diluents, the wetting temperature and the curing degree during the Infiltration process influence the wettability and adhesive interaction between resins and carbon fibers; the dynamic advancing contact angles and surface tension between carbon fibers and resins were analyzed using interface tensiometer; work of adhesion under different conditions was studied by means of Young-Dupre method to make the characterization of surface adhesion. The results showed that the resin system we designed can complete the wetting process spontaneously; In addition, the diluents structure can impact on the wettability, specific performance in: PEGDGE>BPE06>BDDGE. The wettability between resins and carbon fibers can be improved by increasing the temperature. And the wettability and adhesion between epoxy system and fibers improved as curing time (degree) expanded.We also prepared the HF10carbon fiber reinforced epoxy resin matrix composites, interlaminar shear strength (ILSS) of the composites were measured by universal material testing machine to analyze the interfacial properties. We studied how wettability, the wetting temperature and the wetting time influence the ILSS. The results showed that good wettability between epoxy resins and carbon fibers is a important premise to obtain composite with good interfacial properties, since wettability of the system with PEGDGE is better than that of the system with BDDGE or BPE06, the corresponding composite has better interfacial bonding property; the wettability is not the only factor that influence the interfacial bonding strength, it is also affected by the curing degree of the resin system, the interfacial property got better with the development of curing degree of the matrix epoxy. When the mole ratio of the body resin and the diluent is100:10, the system curing degree is the highest, the composite obtained the highest ILSS; improvement of the wetting temperature can promote the composite’s interfacial bonding property; under the same wetting temperature, the impact of wetting time on the final ILSS is not obvious, but if epoxy cured during the wetting process, ILSS and interfacial bonding property of the composite will improve.We used viscosity and isothermal exothermic temperature to character rheological properties and heat release characteristics of the system under process temperature. The result showed that the resin system we studied has long pot life and adjustable heat release characteristics. |
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