Research On PEEK-based Carbon Fiber Prepreg Tow Forming Process

Carbon fiber(CF),known as the king of new materials,and polyether ether ketone(PEEK)resin,a high-performance thermoplastic resin,have been widely used in aerospace,automotive,transportation,medical and other fields as a thermoplastic composite material.However,PEEK and CF have problems with high impregnation difficulty,low fiber content,and poor interlayer shear performance,which limits the application of PEEK-based carbon fiber preimpregnation tow in key structural fields.Therefore,preparation pre-impregnation tow with good performance is of great practical significance.Based on this,this project conducts equipment design and process research on the preparation of PEEK based carbon fiber prepreg tow,which is a beneficial exploration for the preparation of high-performance continuous carbon fiber prepreg tow.The main work of this paper is as follows.(1)Fiber spreading platform construction and fiber spreading research for carbon fiber precursor based on mechanical fiber spreading method.First,the structure design of the fiberexpansion device and the fiber-expanding experimental platform are set up.Second,four parameters are studied,including initial tension,number of straight bars,number of convex bars and yarn speed,studied.At the same time,the width and defects of the fiber expanding on the extension bar are counted.The results show that: 1)When the optimal fiber spreading process parameters are initial tension 5N,0 straight rods,3 convex rods,and 2.3m/min collection speed,the best fiber spreading width is 13 mm.2)The causes of fiber-spreading gaps,fiber bundle abrasion and fluffing,and fiber bundle break defects during CF fiberspreading were analyzed.The fiber spreading gap is mainly caused by the twisting of local tows in the fiber bundle,the wear and fluff mixed in the moving fiber bundle;the wear and fuzz of the fiber bundle are mainly caused by the excessive friction between the fiber bundle and the spreading rod;The bundle breakage is caused by the fact that the tensile force on the CF during the spreading process is greater than the limit of the CF itself.(2)Based on the thin film melt impregnation method,the prepreg tape fusion composite experimental platform was built and prepared.First,the melting composite melting mechanism is designed,and the prepreg zone preparation platform is set up.Secondly,the impregnation mechanism of the prepreg strip is analyzed.It is found that the time of fully impregnating the fiber bundle with resin is directly proportional to the viscosity of the resin(μ),the diameter of the heating roll(R),and inversely proportional to the width of the fiber extension(w),the initial tension(N).Then,the impregnation effect of PEEK and CF at different temperatures was analyzed,and the lowest composite temperature was 370 ℃.Orthogonal experiments with three factors and three levels were set for the parameters of the melting composite process.The effect of the process parameters on the porosity and fiber content of the prepre-preg zone was analyzed.Through the orthogonal experiment range and variance analysis,it was found that when the process parameters were temperature 380°C,carbon fiber width 13 mm,and fiber collection speed 2.3m/min,the porosity of the prepreg tape was the smallest,and the corresponding mass fraction of CF in the prepreg tape was70.14%,and through the layer The interlaminar shear strength obtained from the interlaminar shear strength test is 91.66 MPa.(3)Preparation and research of prepreg tow based on pultrusion mechanism.Firstly,the pultrusion mechanism was designed and the prepreg tow preparation platform was built.Then,the tensile experiments were carried out on the prepreg tow prepared at 360°C,370°C,380°C,and 390°C.The average tensile strength of the prepreg tow decreases first and then increases with the increase of the melting and compounding temperature of the prepreg tow in the mechanism.The lowest tensile strength of prepreg tow is 1230.17 MPa at ℃.Finally,differential scanning calorimeter experiments were carried out on prepreg tows prepared at different temperatures.The results showed that the melting peak of prepreg tows did not change significantly with the increase of temperature,indicating that in the temperature range of 360°C-380°C The lower PEEK is completely crystallized.