Short cellulose nanofibril/polyvinyl alcohol nanocomposite fibers

Short cellulose nanofibrils (SCNF) were investigated as a reinforcement for polyvinyl alcohol (PVA) fibers. SCNF fibers were mechanically isolated from hard wood pulp after enzymatic pretreatment. Various levels of SCNF were added to PVA and gel-spun into continuous fibers. The molecular orientation of PVA was affected by a combination of wet drawing during gel spinning and post-hot-drawing at a high temperature after drying. A maximum total draw ratio of 27 was achieved with various SCNF contents investigated. The PVA crystal orientation increased when small amounts of SCNF were added, but decreased again as the SCNF content was increased above about 2 or 3%, likely due to SCNF percolation resulting in network formation that inhibited alignment. SCNF fillers were effective in improving PVA fiber tensile properties (i.e., ultimate strength and elastic modulus). Shifts in the Raman peak at -1095 cm"1, which were associated with the C-O-C glycosidic bond of SCNF, indicated good stress transfer between the SCNF and the PVA matrix due to strong interfacial hydrogen bonding.