Research On The Rheological Properties Of Carbon Fiber Reinforced Nylon And Its Flow Behavior During Injection Molding

Carbon fiber reinforced nylon has been widely used in aerospace,electronic appliances and other fields in recent years because of its high strength,good toughness and high temperature resistance.By adding an appropriate amount of carbon fiber,the mechanical properties of nylon can be significantly improved,but at the same time the fluidity and moldability of nylon can be reduced.At present,although high-performance carbon fiber-reinforced nylon products can be prepared by injection molding,the influence of carbon fiber content on material rheological properties,the flow law of melt in injection molding and fiber orientation and other mechanism issues need to be explored urgently.In view of this,this article takes carbon fiber-reinforced nylon as the research object.Through steady-state and dynamic rheological experiments,the rheological properties and laws of carbon fiber-reinforced nylon were studied.Through carbon fiber reinforced nylon injection molding simulation modeling,the flow behavior and law of melt in injection molding were studied.The main research contents are as follows:(1)Research on steady-state rheological properties of carbon fiber reinforced nylon.Carbon fiber-reinforced nylon pellets with different fiber content were prepared by melt blending and extrusion process,and steady-state rheological experiments were carried out with the help of a capillary rheometer to obtain the influence of shear rate,temperature and fiber content on the apparent viscosity of the blend system.The microscopic morphology of the extruded spline was observed by scanning electron microscope,and the mechanism of the influence of carbon fiber on the steady-state rheological properties of the material was analyzed.The results show that the steady-state rheological properties of the material are the result of the joint effect of carbon fiber and nylon matrix.The melt rheological properties are the best when the fiber content is 10wt%,followed by 30wt% melt rheological properties,20wt% and 40wt% melt rheological properties are the worst;(2)Research on the dynamic rheological properties of carbon fiber reinforced nylon.The carbon fiber reinforced nylon flat plates with different fiber content were prepared by the molding method,and the dynamic rheological experiment was carried out with the aid of a rotary rheometer to obtain the influence of fiber content and scanning frequency on the complex viscosity,storage modulus and loss modulus of the blend system.Compared the apparent viscosity results of the steady-state rheological experiment and analyzed the difference between the two.The results show that the complex viscosity and apparent viscosity of the material have similar changes with frequency and fiber content,but the complex viscosity of each fiber content material is greater than the apparent viscosity;(3)Research on simulation modeling of carbon fiber reinforced nylon injection molding.Based on the i ARD-RPR fiber orientation model,combined with the actual injection process,the injection molding simulation model was constructed.CT scanning experiments and uniaxial tensile experiments were carried out for 10wt% fiber content materials,and the experimental and simulation results of fiber orientation and elastic modulus were compared.The results show that the maximum error of fiber orientation is 7.35%,the relative error of elastic modulus is 12.76%,and the simulation model has high accuracy;(4)Research on the flow behavior of carbon fiber reinforced nylon injection molding.Based on the injection molding simulation model,through univariate experiments,quantitatively characterized the flow behavior of the melt during injection molding,and analyzed the influence of fiber content,mold structure and process parameters on fiber orientation,shear rate and shear stress.