Research On Continuous Carbon Fiber Reinforced PA6 Composites

As a new generation of high-performance carbon fiber composites,Continuous carbon fiber reinforced thermoplastic resin matrix composites(CFRTP)has excellent properties such as light weight,high strength,easy processing and recycling.Continuous carbon fiber reinforced nylon(PA)composi tes,which are thermoplastic resin based composites with high performance and widely used,have been successfully applied in aerospace,medical instruments,energy and other fields.As a kind of engineering plastics,PA6 has excellent mechanical and processing properties.It is of great significance to study the continuous carbon fiber(CCF)reinforced PA6 composites.CCF/PA6 prepreg tape was prepared by melt impregnation process.The effects of different process parameters on mechanical properties,size and surface quality of prepreg strip were studied.And the optimum process conditions were obtained.By universal material testing machine,miniature optical microscope,scanning electron microscope(SEM),dynamic mechanical analyzer(DMA),thermogravimetric analysis(TG),differential scanning calorimetry(DSC)and X-ray diffraction(XRD),etc.The mechanical properties of the composite material,the surface quality,cross section shape,dynamic mechanical behavior and thermal stability of melting and crystallization behavior and morphology and so on were studied.To explore presoak with secondary processing molding,part drawings for CAD drawing and assembly of continuous fiber reinforced thermoplastic pipe molding line device.Using continuous glass fiber reinforced polyethylene(CGF/PE)and self-made CCF reinforced polylactic acid(PLA)and PA6 prepreg tape as raw materials,CGF/PE,CCF/PLA,CF/PEEK,CCF/PA6 pipes were prepared respectively.The optimum process conditions of all kinds of pipe material package.The differences between the thermal stability and crystallization melting behavior of CCF/PA6 tube and tape were also investigated.The optimal process conditions of CCF/PA6 prepreg are follows: mold temperature is 250℃,tensioning force is 13 N,fiber content changes little with the influence of traction speed,4-6r/min is selected.The preheating and predispersing device can act as the initial dispersing function of the fiber.When the distance between the calendering roll and the die is rela tively close,the surface quality of the prepreg strip is better.The mechanical model of the fiber shows that the application of tensioning force helps to disperse the fiber and reduce the thickness of the prepreg zone.The mechanical properties of CCF/PA6 composites increase a lot with the increase of fiber content in a certain range.The prepreg tape with high fiber content is difficult to achieve good impregnation,and the fiber is not completely coated by resin and appears exposed,resulting in a large decrease in tensile properties and E’.SEM images show that when the fiber content is relatively low,the resin is easier to penetrate into the fiber layer,and the resin plays a better impregnation effect on the fiber.The results of DSC show that the addition of CF could not only promote heterophase nucleation,but also inhibit the movement of molecular chains and affect grain growth,thus inhibiting the dual effects of crystallization.Heterogeneous crystallization nucleation promotion of presoak tape resin compared with pure PA6 resin material to shorten the crystallization time,CF inhibitory molecule chain movement affect crystal growth compared with pure PA6 resin presoak with PA6 in lower crystallinity appeared,but different fiber content on the crystallization rate is not too big effect,at the same time the CF to join changed the crystal type of resin matrix,and some alpha formed gamma crystal shape.The XRD results show that the crystal morphology of PA6 resin in the prepreg zone is changed under the action of room temperature and quenching of metal cooling of calender roller during the prepreg process.TG show that the addition of CF had an effect on the thermal stability and thermal degradation rate of the resin.A simple cutting device designed to control the width of continuous fiber reinforced thermoplastic prepreg was designed to complete the CAD drawing work and assemble the pipe forming line.CGF/PE,CCF/PLA,CCF/PA6,CF/PEEK continuous fiber reinforced thermoplastic resin based tu bes were prepared,and the optimal preparation conditions for different types of tubes were obtained.The feasibility of the experimental mould and the operability of the pipeline production are proved.The preparation conditions of various types of tubes are as follows: traction speed of 4-6r/min,vacuum degree of-0.08--0.1 MPa,spray cooling simultaneously.Temperature has a great influence on pipe forming.The shrinkage of prepreg zone is serious due to molecular interception of resin matrix at too high temperature.At the same time,the enhanced fluidity of the resin leads to the retention of the resin on the surface of the pipe and the formation of white spots The set temperature of the two-section barrel for pipe processing is 150 and220℃ for GF/PE,150 and 225℃ for CF/PLA,190 and 260℃ for CF/PA6,410 and 405℃ for CF/PEEK.CCF/PA6 tubes are composed of multiple layers of strips,which have lower thermal stability and melting poin t than strip due to smaller specific surface area,and lower crystal lization rate and crystallinity than strip.