Study On Interface Modification And Electromagnetic Shielding Properties Of Carbon Fiber Reinforced Polyether Ketone Ketone Composites

Carbon Fiber Reinforced Thermoplastic Composites(CFRTP),with its advantages of high specific strength,good impact resistance and short molding cycle,has gradually become one of the new development directions of Composites in the field of aerospace.However,the non-polarity and low wettability of carbon fiber(CF)limit the interfacial bonding between CF and thermoplastic resin,resulting in the mechanical properties advantages of CFRTP cannot be fully utilized.The interface problem of CFRTP becomes the biggest obstacle to its further development in structural and functional materials.On the other hand,with the advent of THE 5G era and the rise of big data applications,the application of various electronic devices in civil and military fields is increasing.Electromagnetic interference caused by electromagnetic radiation not only seriously affects the stable operation of such electronic products,but also threatens the physical and mental health of ordinary people.This requires that in the process of gradually replacing traditional materials,CFRTP not only needs to have excellent mechanical properties,but also needs to have high electromagnetic shielding efficiency to meet the actual application requirements.Therefore,this paper proposes to study the surface treatment of CF and the interface modification between CF and thermoplastic resin matrix,in order to realize the integration of structure and function of CFRTP.In this paper,Polyether ketone ketone is firstly selected: PEKK(carbon fiber reinforced polyether ketone ketone(CF/PEKK)composite laminates were prepared by vacuum molding process.The condensed structure evolution of PEEK resin and its interface structure with CF were systematically studied under different molding temperature and pressure gradient.The correlation mechanism between structure and mechanical properties of CF/PEKK composites under different molding conditions was analyzed.The results show that under the molding temperature of 365?and the pressure of 5.0-6.0 MPa,the crystal structure of PEKK is the most perfect,the crystallinity of PEKK is 11.61%,and the comprehensive mechanical properties of CF/PEKK composites are the best,the tensile strength is 965 MPa,the bending strength is 849 MPa.When the interlaminar shear strength is 59 MPa,the main failure modes of the composites are resin cracking and interlaminar Z-shaped fracture.Then,in this paper,acetone reflux was used to remove the original sizing agent for CF,and mielic acid was used to activate THE surface of CF.Then,sulfonated polyether ether ketone(SPEEK)/graphene oxide(GO)was used to prepare the modified CF reinforced PEKK composite by vacuum molding process.The results showed that SPEEK/GO sizing significantly increased the oxygen/carbon ratio and surface energy of carbon fibers without damaging the strength of CF,and enhanced the wettability of CF to the resin.The surface elements and microstructure of activated CF can be regulated by embedding the GO lamellar with multiple functional groups in SPEEK sizing layer,which synergistically enhances the interface bonding of CF/PEKK composites.The bending strength,interlaminar shear strength and residual compressive strength of the composites increased from 849 MPa,59 MPa and 186 MPa to 1409 MPa(66%),82 MPa(39%)and 260 MPa(41%),respectively.The interlaminar damage resistance of composites is also improved,and the bending failure mode is changed from interface debonding to serrated cracking and fiber fracture of matrix resin.Finally,the surface metallization of CF fabric(Ni/Fe-CF)was carried out by electrodeposition of Nickel-iron alloy(Ni/Fe),and SPEEK/GO combined sizing was used to improve the interface properties of CF/PEKK composites,and the CF/PEKK composites with integrated structure and function were prepared based on the optimal molding process.The results show that the introduction of Ni/Fe alloy improves the electrical conductivity of CF fabric and the magnetic properties of the composites.The electromagnetic shielding efficiency(EMI SE)of the composites increases from 17 d B to 40 d B,and the absorption power coefficient of electromagnetic waves increases by 136.9% compared with that of pure Ni composites.In addition,the bending strength and interlaminar shear strength of CF/PEKK composites prepared by SPEEK/GO combined with sizing modified Ni/Fe-CF are 19.9% and 32.5% higher than those of unsizing composites,respectively,and the interface debonding phenomenon of composites under bending failure is improved to some extent.