The Preparation Of Hydrophobic Nanocellulose And Its Application In Pulp And Paper

Under the current situation of the exhausting non-renewable resources such as coal, oil andnatural gas, many efforts have been directed at extending the utilization of renewable resourcesfor new energy and new materials. Cellulose is the most abundant renewable biopolymerwhich presents primarily in wood biomass. For the past few decades, cellulose hasattracted attention as one of the promising polysaccharides for accomplishing highlyengineered nanoparticles, which can be applied in many areas. In this paper,nanocellulose was prepared by TEMPO/NaBr/NaClO oxidation and characterized. Theobtained nanocellulose was surface modified by octadecylamine (ODA) and thenapplied in the pulp to evaluate the effect of the hydrophobic nanocellulose on the sheetproperties.nanocellulose were prepard by TEMPO/NaBr/NaClO oxidation of cotton dissolvingpulp (DSP), bleached softwood kraft pulp (KP) and aspen alkaline peroxidemechanical pulp (APMP) and successive ultrasonic treatment. The resulting TONCwere characterized by using Fourier transform infrared spectroscopy (FTIR), Zetasizer,X-ray diffraction analysis (XRD), Atomic force microscopy (AFM) and universaltesting machine. The results show that, the TONCs from different materials weredifferent in carboxylate content, Zeta potential, polymerization, as well as crystallinity,grain size.TONC from KP has the highest carboxylate content. The crystallinity andgrain size changed insignificantly after the oxidation.To achieve the hydrophobic nanocellulose, TONC were surface modified by ioniccomplexation (electrostatic adsorption) with octadecylamine (ODA).carboxylate-to-ODA ratio was set as1:1,1:2,1:3and1:4, respectively, to achieveproducts with different hydrophobicity. The hydrophobic TONC were characterized byFTIR,conductometric titration (CT), N elemental analysis, water contact angle, X-raydiffraction (XRD) and thermogravimetric analysis (TA). The results show that TONCsurface carboxyl groups was substituted with ODA completely when the carboxylate/ODA ratio was higher than1:2. the contanct angle of the nanocellulose film beforeand after surface modification demonstrated that nanocellulose has been trasformedto be hydrophobic. The thermal stability of TONC was slightly increased after themodification.TONCs before and after modification were applied in the BCTMP, and the tensileindex,tear index, brightness, air permeability and sizing degree of the handsheet were evaluated. The results showed that the tensile index and tear index of pulp increased by51%and16.7%, respectively, by adding TONC in the pulp, while the hydrophobicnanocellulose does not improve the tensile index. Depending on the amount of addednanocellulose, the air permeability of the sheet was reduced with various degrees.When10%of TONC after modification was added, sizing degree was at mostincreased by5.6-fold. Relative to adding into pulp, when hydrophobic nanocellulosewas coated on surface of paper, greatimprovements were achieved in sizing degrees.