Study On The Properties Of Carbon Fiber Reinforced Nylon 6 Composite With Amino Functionalization

Carbon fiber?CF?has the characteristics of high strength,heat resistance,corrosion resistance,etc.It is considered to be an important milestone in the development history of fiber materials.However,due to the low content of CF active nitrogen?N?and oxygen?O?functional groups produced by the spinning process,the surface roughness is low,and it is not easy to combine with the matrix,resulting in poor interface strength of the CF and PA6 matrix and reduced performance of the composite material.In order to expand the application field of CF/PA6 composite materials,CF surface modification has far-reaching significance.There are various methods of CF surface modification,but they all have shortcomings such as large damage to CF mechanical strength,low surface adhesion,and poor wettability.The method of amino functional graft modification can introduce active amino groups and other functional groups,which is effective It can make up for the surface defects of CF,improve the wettability of CF surface,enhance the compatibility of CF and PA6matrix,and thus improve the performance of CF/PA6 composite materials.In this paper,the pretreatment method is used to introduce carboxyl groups on the surface of carbon fiber?CF?,and then chemical grafting method is used to make it with different amounts of diethylenetriamine,monomer tetraethylenepentamine?TEPA?and polyamine.The molecular polymer Polyethylene Polyamine?PEPA?undergoes a dehydration condensation reaction,explores the effect of the number of amino groups on CF performance,and prepares a CF/PA6 composite material.Scanning electron microscope?SEM?,atomic force microscope?AFM?,X-ray photoelectron spectroscopy?XPS?,Raman spectroscopy?Ramam?,thermogravimetric analysis?TG?,interlayer shear strength?ILSS?,polarized light microscope,Fourier infrared spectroscopy?FTIR?,monofilament tensile strength test,tensile strength,bending strength,impact strength test and hygrothermal resistance test and other analysis methods systematically analyze different modified CF and CF/PA6 composite materials,conclusion as below.1.SEM observed at 90?,4h,DETA grafted onto the CF surface of the granular graft is densely distributed and the most,the tensile strength of the monofilament reached 4.62GPa;Infrared spectrum analysis showed that characteristic peaks such as N-H at 3270cm^-1 and 1540cm^-1,and C-N at 1450cm^-1 appeared.TG characterization results show that when the temperature is raised to 600?,the mass loss of DETA grafted CF?CF-g-DETA?is 8.4%,which also confirms that DETA is grafted to the surface of CF,and the optimal modification condition is 90?.4h.Raman spectroscopy analysis showed that the Raman R value of CF-g-DETA is 42.9%higher than that of desizing CF?D-CF?.XPS analysis shows that the O/C and N/C of CF-g-DETA are improved by 23.31%and 17.07%compared to D-CF.It is further confirmed that the surface of CF was modified by DETA grafting at 90?for 4h.2.At 90?,4h,using different amino functional groups DETA,TEPA and PEPA grafted to the CF surface.Infrared spectroscopy analysis showed that the characteristic peaks of the three amino functional groups at 3270cm^-1 and 1540cm^-1N-H,1450cm^-1 C-N and 1650cm-1 O-C-O showed that different amino functional groups were grafted to the CF surface.AFM observed that the surface roughness of CF modified by different amino functional grafts was significantly increased,and the roughness of PEPA grafted CF?CF-g-PEPA?was the largest,reaching 83.2nm.The contact angle of CF-g-PEPA observed by polarizing microscope is 135°,followed by TEPA grafted CF?CF-g-TEPA?is 123°.XPS shows that the N content of CF-g-PEPA is up to 18.92%.The mechanical property test shows that the average monofilament tensile strength is 5.01 GPa,which proves that the greater the number of amino functional groups,the better the effect of making up the CF surface damage.The CF has the best mechanical properties and the best CF-g-PEPA.3.Using different amino functional grafting modified CF/PA6 to prepare composite materials.SEM observed that as the number of amino functional groups increases,the CF-g-DETA/PA6,CF-g-TEPA/PA6,CF-g-PEPA/PA6 composites have a tighter interface between the CF and the matrix PA6,CF-g-There are no gaps and cracks between the two phases of PEPA/PA6 composite materials,and the interface adhesion is the best.The interlayer shear strength?ILSS?of CF-g-PEPA/PA6 composite is the largest,reaching 58.6MPa.The tensile strength,bending strength and impact strength of the three composite materials are improved compared with D-CF/PA6.The best CF-g-PEPA/PA6 composite material reaches 125.6MPa,208.6MPa and 70.6 KJ/m²respectively;The minimum moisture absorption rate of CF-g-PEPA/PA6 composite material is 6.22%,which is 30.4%lower than that of D-CF/PA6.It was confirmed that the introduction of amino functional groups can improve the comprehensive performance of the composite,and the increase in the number of amino functional groups improves the interfacial compatibility of the composite and the overall performance.CF-g-PEPA/PA6 is optimal.