Integrated Impact-electrostatic Method For Recycled Short-chopped Carbon Fiber Dispersion,collection,Orientated-flocking

In recent years,carbon fiber reinforced polymer matrix composites(CFRPs)waste has risk for the environment.As a green and economic way,recycled carbon fiber has been widely used in the recovery of CFRPs,but the recycled carbon fiber is usually random chopped carbon fiber clusters.The research shows that the dispersion and orientation of carbon fiber are the premise and key to obtain high-performance composites.For the dispersion method,the method of functional additives will cause secondary pollution and long treatment time;Traditional physical methods are easy to cause secondary damage to the fiber,which can affect its performance.In terms of orientation,electrostatic flocking can only achieve the orientation in the vertical direction.Therefore,aiming at the above key problems,this study puts forward the technical process of impact dispersion,electrostatic collection,polarization orientated-flocking.The main contents and conclusions are as follows:(1)A dispersion evaluation system based on depth-first search algorithm and area matching method was proposed.The deagglomeration efficiency βc and distribution coefficient γc were defined,which could effectively reflect the deagglomeration and accurately characterize the distribution of carbon fibers.The angle distribution of carbon fibers is obtained by Canny edge detection operator and central moment.(2)The non-destructive dispersion of chopped carbon fibers was achieved via the highpressure difference shearing force generated by pneumatic impact.With a high-speed camera,the impact dispersion process includes:peripheral monofilament separation,cluster disintegration,tip conization and dispersion.The deagglomeration efficiency obtained at 98%with flow rate of 5 m3·h-1,initial mass of 0.010 g and fiber length of 1 mm.(3)The collection efficiency of adhesive cladding metal electrostatic collection,active excitation dielectric cladding collection and passive excitation dielectric cladding collection is 82%,62%,and 57%,respectively.The operating parameters such as voltage,thickness and configuration and various charged configurations were compared,finding that the relaxation time of charge saturation and charge polarization is very short due to the conductive characteristics of carbon fiber.Besides,the collection process is less affected by dielectric polarization field,which was promising under low-voltage.The distribution of collected fibers on the plate was adjusted by the active excitation process,and the low-voltage carbon fiber electric collection technology without insulation failure was explored via the passive excitation collection process.(4)The high value secondary utilization technology path of collected chopped carbon fiber was investigated.The secondary excitation of the dielectric achieved the stripping,orientation and flocking of fiber,which could maintain orientation,exert anisotropy,and achieve secondry utilization with high added value efficicently.Moreover,the process of electrostatic collection and polarization orientated-flocking has advantage of flocking at each angle.The flocking of copper foil,resin and prepreg has been carried out,all of which have a good degree of orientation.