Research On Fast Curing Epoxy Resin For RTM Process

Due to many excellent characteristics such as light weight and high strength,fiber reinforced polymer(FRP)composite has become an ideal lightweight material in the aerospace and automotive fields.Resin transfer molding(RTM)process is an increasingly common molding technology used to produce FRP composite materials.Nevertheless,in order to achieve mass production of FRP composite parts,the development of a fast-curing epoxy resin system suitable for the RTM process has become a research hotspot in recent years.The main research contents and results of this article are as follows(1)Bisphenol A diglycidyl ether(DGEBA)epoxy resin diluted with allyl glycidyl ether(AGE)was mainly cured by 1-benzyl-2-methylimidazole(1B2MZ).The effect of isophorone diamine(IPDA)content on the curing kinetics and mechanical properties of the DGEBA-AGE-1B2MZ system was studied.Non-isothermal differential scanning calorimetry(DSC)results indicated that when the content of 1B2MZ was small,1B2MZ first underwent anionic polymerization with epoxy groups,and the remaining epoxy groups needed to be completely cured by imidazole regeneration.Nevertheless,as the IPDA content increased,the epoxy group first underwent an addition reaction with IPDA,and the remaining epoxy group was completely cured mainly by an anionic polymerization reaction with 1B2MZ.The change trend of activation energy(Ea)with degree of curing(?)determined by Ozawa-Flynn-Wall method indicated that the amount of IPDA had a great influence on the reaction curing kinetics.Finally,the resin system with the best mechanical properties could be cured within 20 min at 120?.(2)DGEBA epoxy resin diluted with AGE was mainly cured with 2-ethyl-4-methylimidazole(2E4MI).The effect of IPDA content on the curing kinetics and mechanical properties of the DGEBA-AGE-2E4MI system was studied.The results demonstrated that as the IPDA content increased,the first low-temperature shoulder peak on the non-isothermal DSC curve became more and more obvious,indicating that in the initial stage of curing,more and more IPDA reacted with epoxy groups.The remaining epoxy groups mainly underwent anionic polymerization with 2E4MI.The relationship between Ea and ? determined by the Ozawa-Flynn-Wall method depended largely on the content of IPDA.Finally,the resin system with the best mechanical properties could be cured within 15 min at 120?.(3)DGEBA epoxy resin diluted with AGE was mainly cured with N-(3-aminopropyl)-imidazole(API).The effect of IPDA content on the curing kinetics and mechanical properties of DGEBA-AGE-API system was studied.Non-isothermal DSC results showed that as the IPDA content increased,epoxy groups first underwent addition reaction with the primary amine groups from the molecular structure of IPDA and API,and the remaining epoxy groups mainly underwent anionic polymerization with the API.The relationship between Ea and?determined by the Ozawa-Flynn-Wall method revealed the complexity of the curing reaction.Finally,the resin system with the best mechanical properties could be cured within 10 min at 120?.(4)The above three preferred fast curing resin systems were used for gel time and viscosity tests to determine the injection temperature of the VARTM process.Afterwards,with these three resin systems as the resin matrices,the corresponding glass fiber reinforced composite materials were prepared respectively.The fiber volume content,tensile strength,flexural performance and short beam shear strength of the composite material were tested The results demonstrated that the best resin system compounded with API and IPDA not only had excellent process performance,but when it was used as a resin matrix,the fiber volume content of its glass fiber reinforced composite material was 53.86%,and had the best mechanical performance.Therefore,the best resin formulation compounded with API and IPDA could be used as a fast curing resin system suitable for RTM process.