| Continuous fiber reinforced thermoplastics composite are widely used in aerospace,automobile,transportation,chemical industry and other fields due to their excellent mechanical properties,long-term preservation,recyclability and good technological properties.In this paper,continuous glass fiber reinforced PVC prepreg were prepared by wet powder impregnation method using PVC resin as matrix phase and continuous glass fiber as reinforcement phase.Based on the principle of volume conservation,a physical and mathematical model was established.The effects of particle size and suspension concentration on the properties of prepreg were verified by numerical solution and experimental verification.Then the prepreg were prepared by molding process to prepare continuous glass fiber reinforced PVC composite.The effects of molding process and material parameters on the properties of the composite were studied.The main research work is as follows:The prepreg production equipment was designed and developed,and the physical mathematical model of powder deposition cube unit was established based on the principle of volume conservation.The validity of the model was verified by experiments.The optimum powder diameter and suspension concentration could be determined theoretically by using the model to guide the formulation of process parameters.The effects of different parameters on the fiber content of prepreg sheets were studied by experiments.The results showed that the fiber content of prepreg could be increased by reducing the concentration of suspension,increasing the pulling speed and reducing the wrapping angle of suspension dispersion roll in a certain range,and the relationship between the properties of prepreg and the material parameters was proved.The effects of material parameters(particle size of PVC,fiber content and ACR processing aids)and molding process(molding temperature,molding pressure and molding time)on the mechanical properties of composite were studied by melting prepreg into standard splines.The results show that the optimum tensile strength,flexural strength,interlaminar shear strength and impact strength are 345 MPa,302 MPa,28.2 MPa and 198.6 kJ/m2,respectively,when the powder diameter is 50 micron,the fiber mass friction is 65%,the ACR mass friction is 2%,the molding temperature is 160℃,the molding pressure is 6 MPa and the molding time is 10 min.The effects of silane coupling agents(KH550,KH560 and KH570)on the interfacial properties of composites were studied.The results showed that KH550 had the best effect on the interfacial strengthening.The interfacial bonding strength was enhanced,and the tensile strength,flexural strength,interlaminar shear strength and impact strength were increased by 31%,26.5%,22.3%and 34.2%,respectively.The effects of different heat stabilizers on the heat resistance of composites were studied.The results show that organotin thermal stabilizer has the best thermal stability and heat resistance.The thermal deformation temperature is 180℃ and Vicat softening temperature is 109.5℃. |
