Preparation And Properties Of Sizing Agent For Carbon Fiber Reinforced Polypropylene Composite

Carbon fiber-reinforced polypropylene(CFRPP)composites have the advantages of low density,high specific strength,specific modulus,and low production cost.However,carbon fiber-reinforced polypropylene composites have poor interfacial properties,uneven dispersion,and easy condensation.Now,the research of carbon fiber sizing agent for polypropylene matrix is few,so the study and preparation of carbon fiber sizing agent for polypropylene matrix has attracted more and more attention.This study designed the main components of maleic anhydride and dodecene to control the polarity of polymers through the ratio of maleic anhydride to dodecene and the introduction of long carbon side chains through dodecylamine.From the perspective of thermodynamics,the sizing agent can theoretically calculate the surface energy modification of carbon fiber and the adhesion and dispersion between different polar polypropylene as a guide to improve the interfacial properties and dispersion of carbon fibers in polypropylene matrix.The use of sizing-treated carbon fibers for the preparation of polypropylene composites improves the interfacial bonding strength and improves the dispersion.In this study,random copolymers of maleic anhydride and dodecene were prepared by free radical solution polymerization,and random copolymers containing different ratios of maleic anhydride/dodecene units were prepared as MAC sizing agents according to the ratio of different feeds.On the basis of MAC,through the modification of dodecylamine,the long carbon side chain is further introduced to prepare the MAC aminating modification MAC12-12,and a series of MAC12-12 is prepared according to the amount of dodecylamine introduced.Through infrared spectrogram analysis(FTIR),nuclear magnetic resonance(~1H-NMR)and thermogravimetric analysis(TGA),the results showed that MAC and MAC12-12 were successfully synthesized as expected,and the product remained stable at temperatures above 200°C,and the processing requirements of the carbon fiber reinforced polypropylene composites were satisfactory.Next,different sizing agents were used to modify the surface of carbon fibers.X-ray photoelectron spectroscopy(XPS),field emission scanning electron microscopy(SEM),dynamic contact angle(DCT),and interfacial shear strength of monofilament composites(IFSS)were used.And other tests have tested and analyzed the surface chemical structure,physical morphology,and the bonding properties with the polypropylene resin matrix of sizing carbon fibers.The results showed that after the MAC sizing carbon fiber,the oxygen content increased,the surface polarity increased,and the interface with the highly polar polypropylene matrix was better;the surface carbon content of MAC12-12 sizing carbon fiber increased,and the surface polarity was low.Low polarity polypropylene matrix interface was good.Then,based on the surface energy of different sizing carbon fibers and polypropylene of different polarities(different MPP content),the theoretical calculations of thermodynamic adhesion were performed.The results showed that the OCF and MAC sizing carbon fibers have weak adhesion in the low-polarity polypropylene matrix,and the thermodynamic spontaneous degree of uniform dispersion and non-agglomeration in the matrix was low,and with the increase of the substrate polarity,the adhesion and the dispersion tendency was improved and uniform;MAC12-12 sizing agent had better adhesion in the low polarity of polypropylene matrix,and the degree of homogeneity of the spontaneous dispersion was higher.With the increase of the polarity of the matrix,the adhesion was decreased and uniform.The decentralization trend declined.Finally,the above slurry carbon fiber is a reinforcement material,and polypropylene is used as a matrix(different MPP content)to prepare a composite material.The effect of sizing treatment on the tensile properties,impact properties,dynamic mechanical properties and melting properties of the composite material was investigated.The results showed that in the two series of sizing agents designed and synthesized in this study,the MAC sizing agent treated carbon fiber had a good reinforcing effect in the highly polar polypropylene matrix;while the MAC12-12 sizing agent treats the carbon fiber in low polarity.The polypropylene matrix had better reinforcement and promoted the dispersion effect.