Wet Spun Fibers from Solutions of Cellulose in an Ionic Liquid with Suspended Carbon Nanoparticles

Wet spun fibers from solutions of dissolving pulp in 1-ethyl-3-methylimidazolium acetate (EmimAc) with up to 50 wt % (based on cellulose) suspended carbon black and graphene nanoplatelets particles were studied. Carbon fillers were dispersed by simple shearing in a Couette type mixer and the resulting spin dope was extruded into a hot water coagulation bath from a single hole spinneret. Microstructure, mechanical properties, and electrical conductivity were assessed as a function of filler loading and discussed in comparison to melt spun fibers with similar fillers. The coagulation process and subsequent drying of wet spun fibers was found to produce a significant microporosity, more so the higher the filler loading. The electrical percolation threshold was quite high in the wet spun fibers and relatively modest values of conductivity were obtained with regard to the high filler loadings. Carbon black was found to be superior to graphene nanoplatelets. This was related to flow-induced orientation effects. The mechanical properties of the carbon-filled fibers were found to be similar or lower compared to the pure cellulose fibers because of low interfacial interactions and formation of microporosity. (C) 2014 Wiley Periodicals, Inc.