Preparation And Properties Of High Performance Continuous Fiber Reinforced Polyetheretherketone Composites

Since the mechanical strength of the short or long fiber reinforced form can not meet the requirements of some aeronautical structures.Moreover,compared with the thermosetting composites,the thermoplastic composites have the advantages of short molding cycle,repeatable processing and high toughness,which makes the continuous fiber reinforced thermoplastic composites more and more concerned by the aerospace industry.Polyether ether ketone(PEEK)as a semi-crystalline thermoplastic polymer,its excellent overall performance,making it widely used as the matrix of high-performance fiber reinforced thermoplastic composite.However,due to the high melt viscosity of PEEK,it is very difficult to prepare continuous fiber reinforced PEEK(CXF/PEEK)composites with good resin impregnation.In order to solve this problem.In the early stage of the research group,the PEEK fibers were intimately mixed with the reinforcing fibers in the form of wrapped yarns,and then the wrapped yarns were knitted into unidirectional cloth for hot press molding to prepare CXF/PEEK.However,due to the cumbersome weaving process takes a lot of time and high cost,so this paper designed a new winding pre-compression molding method to prepare unidirectional CXF/PEEK composites.In this paper,the prepreg was obtained by pre-pressing the wrapped yarns,and then used in hot-press preparation to prepare unidirectional CXF/PEEK composites,which further improved the straightness and wettability of the fibers.In order to study the differences in the molding process of different types of reinforcing fibers.Unidirectional CCF/PEEK and CGF/PEEK composites were prepared by winding pre-compression molding method,and the effects of the molding conditions on the properties of the composites were studied.A suitable molding temperature is critical for achieving good thermal properties and mechanical properties for unidirectional continuous carbon fiber reinforced PEEK composites(CCF/PEEK).Since the carbon fiber is a good conductor of heat,theCCF/PEEK is usually produced by thermal degradation at a relatively lower molding temperature and molding time relative to that of the insulating glass fiber.And the appropriate increase in molding time is also conducive to resin impregnation and improve the mechanical properties of composites.The effect of the cooling rate on the tensile and bending properties of the composites is not very significant in the range of the cooling rate studied.But the shear strength is significantly reduced with the increase of the cooling rate due to the change of the matrix crystallinity.However,for unidirectional continuous glass fiber reinforced PEEK composites(CGF/PEEK).The effect of molding temperature and molding time on its thermal and mechanical properties is very similar,showing a significant time-temperature superposition principle.Although the resin impregnation is improved with the increase of molding temperature and molding time,it is more suitable to improve the mechanical properties of the composites by prolonging the molding time due to the sensitivity of matrix to high temperature.With the increase of the cooling rate,the mechanical properties of CGF/PEEK composites decrease to different degrees due to the decrease of the crystallinity of the matrix.However,due to changes in the permeability of the matrix is very small,the mechanical properties of the change is not obvious.