Study On Fiber Reinforced In-situ Polymerized Nylon 6 Resin Transfer Molding Composites

In recent decades,the production and consumption of resin matrix composites have been increasing,the annual output has reached 10 million tons.Among them,compared with thermosetting composites,thermoplastic composites(TPCs)have unique advantages such as higher toughness,good fatigue resistance and recyclability.Therefore,the development and application of thermoplastic composites has become a research hotspot of resin matrix composites at present.The resin transfer molding(RTM)process for forming composite products is independent of the layering design of the fiber prefab,which gives engineers more freedom in designing molds and reinforced materials.Because of its flexibility,the process is considered to be one of the most suitable methods for mass production of small and medium-sized products.However,the high viscosity of the melt in the molten state of most thermoplastic resins makes it difficult to impregnate thick-scale fiber reinforcements,so it is difficult to use thermoplastic resins as resin substrates for high-performance composites directly through the RTM process.In order to solve the problem of thermoplastic resin impregnated fiber,this topic with polyamide 6(PA6)monomers of caprolactam(CL)is on the basis of the in-situ anionic ring-opening polymerization,using thermoplastic resin transfer molding(T-RTM)process,the low viscosity of CL,catalyst and activator mixed melting by homemade resin injection molding machine injection,thus realizing high fiber content and thickness of the fiber reinforced body fully impregnated,and preparation of the excellent mechanical properties of glass fiber reinforced thermoplastic resin matrix composites(GFRTP).In this paper,the glass fiber reinforced nylon 6 in-situ polymerization composite materials(GF/APA-6)in the RTM molding mold design,fiber reinforced layer structure design,feed method was studied,in addition,heat transfer and chemical reaction mixture transformation process,finite element simulation research on the impregnation process flow was conducted to optimize the related process parameters,to improve the quality of products,shorten the molding cycle provides the corresponding theoretical basis.The main research contents are as follows:1.On the basis of the synthesis process conditions of caprolactam anionic polymerization pa-6 studied by predecessors,the composition ratio of active materials was adjusted to solve the problem of caprolactam anionic polymerization inactivation caused by the adsorption of certain water in the storage process of glass fiber cloth,and the APA-6 formulation system suitable for RTM molding process was optimized.According to the requirements of the RTM molding products molding,vacuum assisted RTM mold design and,in addition,also through the design for the reaction system of plastic injection molding machine and all kinds of building thermoplastic resin transfer molding(T-RTM)forming experiment platform,under the condition of constant pressure injection,succeeded in preparation of excellent mechanical properties of GF/APA-6 composite plate.2.Setting up the nonlinear transient coupled heat transfer and resin reaction kinetics model,using the finite element software COMSOL important heat transfer and reaction in the process of RTM molding process for three dimensional simulation research,analyzes the mold temperature,injection temperature,and glass fiber volume content and the key process parameters on the temperature field and stress field of the composite plate in the influence of the reaction conversion rate.3.The reaction mixture flow in the fiber bundle as a porous medium flow,finite volume method is adopted to establish the reaction mixture in RTM processing theory model of impregnated fiber,PAM-RTM finite element software was used to model of porous media under the condition of constant pressure injection filling process was studied,and analyzed the injection temperature,injection pressure,glass fiber volume content of parameters,such as dipping time,the influence of the resin flow and porosity.4.The effects of key technological parameters such as injection temperature,mold temperature,fiber content and injection mode on the thermal properties,mechanical properties and microstructure of GF/APA-6 composites in the RTM molding process were studied to provide certain guidance for the industrialization of GF/APA-6 composites RTM molding.