Study Of Impregnation Process And Application Foundation On The VARTM Molding Process

Vacuum assisted resin transfer molding (referred to as VARTM) is becoming an advanced manufacturing technology in the world for molding composite materials with high-performance and low-cost. This technology helps increase the resin transfer power and remove the air in the mold and the fiber-reinforced materials, what's more, it opens the channel for the resin to flow in the cavity and to form a complete path. This paper systematically studied the epoxy resin systems used for wind turbine blades produced through VARTM process, the compatibility of the treated reinforced fibers and resins, and the impregnation process of the reinforcing fibers with resins; finally, the mechanical properties were studied by using the composite materials molded through VARTM process.The cure kinetics and rheological properties were studied first according to the requirements of the epoxy resin systems used for wind turbine blades molded through VARTM process, and then the curing process of epoxy resin was determined. To improve the infiltrative property of the reinforced fibers with resins, silane coupling agent treatment and heat treatment were carried out on the reinforced fibers, and the results showed that the contact angle became smaller and the infiltrative property was improved between the treated reinforced fibers and the epoxy resin. Then, the research focused on the impregnation process of the fibers with the resin during the VARTM process, and on the permeability of different fibrage methods, different fiber layers and different resins combining with the testing methods of unidirectional and radial penetration. The results showed that the permeability of the reinforced fibers was greatly influenced by different fibrage methods, different fiber layers and different resins.The results have an important impact on the theoretical simulating of the flow pattern of the reinforced fibers and the resin and the filling time of the resin in the reinforced fibers. Finally, the mechanical properties of the composite material products through VARTM technology were studied. The research showed that different fibrage methods had great influences on the mechanical properties, and that the tensile and bending properties of the composite materials using single axial cloth were the best. The results have some directive functions for the choice of reinforced fibers for composite materials.The study of VARTM process has provided theoretical basis for removing the defects such as air bubbles and dry spots, shortening molding cycle and improving the product properties, and has laid a solid technology foundation for the development and application in large scale of the manufacturing technology for high-performance and low-cost composite materials.