The turbulent-flow-assisted electrostatic collection and alignment of recycled short-chopped carbon fiber in gaseous phase

Abstract

Short-chopped carbon fiber is a main recycled product of carbon fiber materials that shows great advantage of anisotropy on mechanical or functional properties; however, their considerable agglomeration leads to limitations of separating and controlling individual fiber’s placement and orientation to fine-tune properties of final composite materials. Here we report a turbulent-flow-assisted electrostatic collection and alignment method that results in exceptional disentanglement efficiency, good collection and launching efficiency with great orientation performance in the gaseous phase. The pneumatic dispersion shows a nearly complete disentanglement efficiency (97 %) at a pressure reduction of 0.5 MPa, which ensures full utilization of electrostatic property for each disentangled fiber. By energization of the dielectric layer at different voltage levels, re-entrainment of conductive carbon fiber was avoided, while the collection and launching efficiency could reach 62 % and 47 %, respectively. By fast-frame imaging, the disentanglement, migration, landing and launching process was studied. The electrostatic polarization for launching leads to free-angle flocking that over 97 % of short fibers were controlled to be aligned within azimuthal angle from 60° to 90° regardless of launching angle. The combined disentanglement and alignment offer an attractive material system for recycling short-chopped carbon fibers and fabricating reinforced or functionalized composite materials.