| Carbon fiber/epoxy composite materials are the ideal materials to meet the lightweight goals of automobiles due to their advantages of light weight,high strength and strong designability.In order to realize the application of carbon fiber/epoxy composite materials in a large batch and fast cycle in the automotive industry,the rapid prototyping process and the rapid curing epoxy resin system are required.The wet molding process is a new type of rapid prototyping process with low manufacturing cost and high degree of automation.However,the domestic research on this process is not deep enough,and it lacks a fast curing resin system adapted to this pro cess.Aiming at the wet molding process,this paper studies a fast-curing resin system suitable for the process,and deeply studies the properties of carbon fiber/epoxy composites prepared by the system.According to the molecular structure of the curing agent and the curing reaction principle of the epoxy resin,several curing agents suitable for rapid curing epoxy resin system were selected,and the effects of different curing agents on the curing reaction rate and curing quality were studied.We got the following conclusions:After compounding the amine curing agent and the imidazole curing agent,it reacts with the epoxy resin through different reaction principles.The original concentrated heat is divided into two steps to make the curing of the epoxy resin more perfect and improve the crosslink density of the cured product.The two curing agents release heat separately,which solves the problems of explosion polymerization and internal defects caused by concentrated heat.At the same time,the reaction time was appropriately delayed.The study found that the tensile strength of the compound system reached 67MPa increased by nearly 20%compared with the single amine curing agent system;the bending strength reached 88MPa increased by nearly 50%compared to the single amine curing agent system;impact The strength has also reached 111 kj·m-2,which is nearly 40%higher than that of a single amine curing agent system.Then,the curing process parameters of the curing agent system with the best performance were studied.By changing the amount of curing agent and the curing temperature,the change of curing reaction rate was explored.By testing the gelation time,curing degree of the resin system,and comparing with the traditional epoxy resin and commercial fast curing epoxy resin system to study the speed of the curing reaction rate,the quality of the cured product and the applicability of the resin performance.The research results show that when the curing agent is added in an amount of 20 phr and the curing reaction temperature is 120℃,the curing time is about 1/5 of the conventional resin system,and the curing degree reaches 98%when the reaction reaches 6 minutes.The tensile strength is 30%higher than conventional resin systems and 10%higher than similar domestic products.The tensile modulus is basically unchanged.The glass transition temperature is 126℃,which is significantly higher than other epoxy curing systems and suitable for wet molding process.Finally,the self-developed fast-curing epoxy resin system is used to prepare the carbon fiber/epoxy composite material model.The physical properties,mechanical properties and resistance of the composite material model prepared with the traditional epoxy resin system and the commercial fast-curing epoxy resin system are Compare thermally.The results show that the self-developed fast-curing epoxy resin system has a viscosity of 230 mPa·s at 60℃,the lowest viscosity and the best wettability among the three resin systems.The carbon fiber/epoxy composite material model prepared by the self-developed fast curing resin system has a fiber volume fraction of 57.31%and a porosity of 4.79%.The tensile strength of the self-developed carbon fiber/epoxy composite material model reached 750MPa.Compared with the traditional epoxy resin system,the tensile strength is still increased by 10%under the condition of greatly shortening the curing time.The tensile strength is also increased by 6%;the bending strength is 675MPa and the bending modulus is 42GPa,which is not much different from the other two systems;the impact strength is 19kj·m-2,which is a composite material prepared by curing traditional epoxy resin Increased by 25%,nearly 20%higher than composite materials prepared by commercial fast-curing resin systems.The self-developed fast-curing composite material has a glass transition temperature of 121℃,which is not only higher than the glass transition temperature of the other two system composite materials,but also higher than the curing temperature of its own wet molding process,indicating that it has a good Heat resistance and small shrinkage. |
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