Solution-based Preparation Technology And Tensile Properties Research Of Carbon Fiber Reinforced Polyether Ketone Ketone Composites

Due to its high temperature stability,excellent mechanical properties,electrical insulation,physical and chemical corrosion resistance and good biocompatibility,polyaryl ether ketone(PAEK)resin is widely used as the matrix of carbon fiber(CF)composites in aviation,automobile,biology,medical equipment and other fields.Because of the insolubility of the molecular chain of PAEK resin and the limitation of melt viscosity,solid-based impregnation methods are usually selected in the preparation of CF/PAEK composites,such as film lamination method,hybrid fiber method,water suspension impregnation method,powder impregnation method and mixed molding method.However,these impregnation methods can not make PAEK resin impregnate into the CF beam fully,causing serious resin enrichment phenomenon,which leads to the poor comprehensive performance of the end product.Compared to other PAEKs,due to the high proportion of ketone bonds in the molecular chain,the polarity of PEKK resin is much greater,which can be dissolved in high-polarity solvents to form uniformly dispersed solutions.Therefore,we creatively prepared CF/PEKK composite by using solution impregnation method with low viscosity and good fluidity colloidal solution,and constructed the composite structure with uniform distribution and strong interfacial bonding.In this paper,we first analyzed the choice of solution parameters in the process of solution impregnation,then prepared CF/PEKK composite with appropriate PEKK colloidal solution,and further optimized the structure of the composite by hot pressing,providing more impregnation choices for the preparation of CF/PEKK composite with compact structure and excellent performance in the future.In addition,we explored the aggregation structure of PEKK resin and the influence of pressure and cooling during hot pressing process on crystallization behavior of PEKK.The first part was to prepare CF/PEKK composite by impregnating CF bundles with PEKK colloidal solution with low viscosity and good fluidity,and then to optimize the structure of prepreg by hot pressing technology.The colloidal size of PEKK resin in the solvent trifluoroacetic acid could be as low as 17 nm,and the viscosity of PEKK colloidal solution could be as low as 681.1 cp when the mass fraction of PEKK was 12%.The addition of 1,2-dichloroethane could further reduce the viscosity of PEKK colloidal solution to 247.5cp.When the impregnation efficiency of PEKK colloidal solution on CF beam was improved,PEKK resin could uniformly attach to the surface of CF.After hot pressing,the composite structure was further optimized,and the contact area of the two increased significantly,further enhancing the effect of mechanical locking.The second part was to investigate the effects of different heat treatment crystallization conditions on tensile properties of CF/PEKK composites and the crystallization of PEKK resins.The experimental results showed that the tensile strength of CF/PEKK composites reached 1.85 GPa and the strength utilization ratio of CF reached 94.9% under the non-isothermal crystallization condition and 360 ? melting temperature.In addition,the interfacial shear strength(IFSS)and interlaminar shear strength(ILSS)of CF/PEKK composites can reach 72.3 MPa and 66.79 MPa respectively.The presence of CF inhibited the crystallization of PEKK resin,making the amorphous structure of PEKK filled the interior of CF bundle in a large area,promoting the infiltration effect of PEKK resin on CF and improving the interface bonding strength.The third part studied the influence of heat treatment conditions on the crystallization behavior of PEKK.The results showed that the heat treatment of heat preservation first and then pressure could promote the formation of PEKK crystal type ? with more stable structure and better thermal properties.On the basis of this heat treatment,isothermal crystallization induced PEKK resin to form crystal type ? and non-isothermal crystallization to form crystal type ?.During the cooling process,the presence of pressure could appropriately reduce the crystallinity of PEKK resin.