Optimization of the pelletization of cellulose fibers for extrusion applications

Cellulose fibers are rarely used for the extrusion of natural fibers composites, mainly due to problems in feeding a material having a so low bulk density. Pelletization of cellulose fibers is a possible solution, it permits consistent feeding into an extruder, but it also causes severe fiber breakage, reducing the strength of the composite. The goal of this study was to optimize the pelletization process for extrusion applications. That for, bleached cellulose fibers were pelletized at different moisture content and with the optional addition of carboxymethyl cellulose. The effects of dry content and carboxymethyl cellulose on the dimensions of the obtained cellulose fibers and on fiber breakage during processing were investigated. Cellulose pellets were found to be larger and more compact with decreasing moisture content and with the addition of carboxymethyl cellulose. Moreover, composites containing 20wt% cellulose fibres were manufactured using a twin screw co-rotating extruder using two feeding methods: pre-blending and side feeder. .in order to compare the ability of the different pellets grades to be dipsersed during processing. The feedability of the pellets was analyzed considering two feeding methods: pre-blending and side feeder. Agglomerates and fibers were measured into the composites materials. The ability of the different pellets grades to be dipsersed during processing was analyzed by measuring the size of agglomerates. The evaluation of the fiber breakage during processing was analyzed by measuring the fiber length within the composite materials.