Research On Preparation And Properties Of Three-dimensional Braided Prepreg

Carbon fiber reinforced resin matrix composite(CFRP)has the characteristics of light weight,high specific strength,high specific modulus,etc.,and is widely used in aerospace,strategic weapons,marine engineering equipment,advanced rail transportation and other fields.With the rapid development of science and technology,the research focus on improving the performance of CFRP products has shifted from resin modification and toughening to overall product structure enhancement,prompting the rapid development of 3D braiding technology in the field of carbon fiber composite materials.At present,the most common three-dimensional weaving technology combined with resin transfer molding(RTM)still has problems of uncontrollable resin content,insufficient resin impregnation and uneven distribution,which ultimately leads to poor product quality stability.If the process of impregnation followed by weaving is adopted,the problems of insufficient resin impregnation and uneven distribution can be significantly improved,which is of great significance for improving the mechanical properties and quality stability of the product.In this study,the thermosetting resin system was first used for the preparation of prepregs that can be used in three-dimensional weaving technology,and the properties of the cured unidirectional yarn and unidirectional plate prepared by the prepreg were studied.Subsequently,the thermosetting prepreg was used to braid the thin-walled round pipe,and the mechanical properties and microstructure of the pipe fittings were investigated.Exploratory research was conducted on thermoplastic prepreg yarns that can be used in three-dimensional weaving technology.It was found that thermoplastic resin polyethersulfone(PES)has a significant toughening effect on the thermosetting prepreg yarn resin system.Finally,the mechanical properties and microscopic properties of the toughened resin The structure was studied.The main conclusions of each chapter of this article are as follows:(1)By comparing the viscosity,mechanical properties,and thermal properties of the three resins BZ-65,BZ-70,and BZ-75,it was found that BZ-70 resin is more suitable for the preparation of subsequent prepregs.Using the prepared prepreg to prepare composite unidirectional plates,the mechanical properties of the unidirectional plates were measured to be excellent,with tensile strength of 1147.33 MPa,bending strength of 1227.34 MPa,and interlayer shear strength of 84.90 MPa.(2)The sampling method was used to test the mechanical properties of the braided pipe fittings.The experiment showed that the tensile strength of the dumbbell shaped specimens of the braided pipe fittings and the hand-laid samples were not much different,and the tensile properties were only reduced compared with the hand-laid samples.5%,indicating that the performance loss of braided pipe fittings is smaller than that of the flat plate,which better reflects the advantages of three-dimensional braiding.(3)The performance comparison of the thermoplastic resin prepreg prepared by solution impregnation-phase inversion method and typical epoxy/DDS resin-based composite materials shows that the PES-based composite materials have more excellent heat resistance,although the mechanical properties are slightly It is lower than epoxy/DDS resin matrix composites,but through fiber interface treatment,it is possible to further improve the mechanical properties of PES resin matrix composites.(4)The performance of modified thermosetting prepreg resin with different contents of PES was studied.It was found that the addition of PES significantly improved the bending strength and impact toughness of the resin casting body,and the microscopic morphology of the impact section of the casting body can be seen After the toughening of the resin impact section,an obvious island structure appears.And when the PES content is 10%,the impact toughness of the resin reaches the maximum value of 13.28 k J/m~2.As the PES content increases,the heat resistance of the resin system continues to improve,and the coefficient of thermal expansion of the resin before and after modification does not change significantly.