Comparative properties of nanofibers produced using unbleached and bleached wheat straw pulps

Abstract

Abstract Unbleached nanofibers (UNF) and cellulose nanofibers (CNF) were produced from unbleached and bleached wheat straw pulps using microfluidizer. The UNF and CNF and their corresponding films were characterized and compared. FE-SEM images showed UNF were thicker than CNF and with increasing passing number from microfluidizer, the diameter of UNF and CNF reduced. UNF films showed higher density, opacity and transparency as well as less water vapor permeation than those of CNF films The highest tensile index obtained for UNF film (114 Nm/g) and CNF film (107 N.m/g) both obtained at energy consumption of 458 kwh/t which was consumed in refiner and microfluidizer. The tensile index decreased at energy consumption higher than 458 kwh/t. The highest burst index of CNF film was 6.9 kPa.m2/g which was achieved using 358 kwh/t in microfluidizer As energy consumption increases, the burst index of CNF film decreased. On the other hand, with the increase of energy consumption and numbers of passes the burst index of UNF films increased, reaching the value of 8.8 kPa.m2/g. Elimination of bleaching has valuable advantages including saving energy, less environmental pollution, higher production yield and less downsizing energy consumption and less finished cost of nanofibers with desired properties.