Decreasing of water absorptiveness of paper by coating nanofibrillated cellulose films

Nanofibrillated films based on TEMPO-oxidized cotton linters were applied to reduce the hydrophilic properties of paper. For this purpose, aqueous dispersions of nanofibrillated cellulose of different composition: 1 and 3% of nanofibrillated cellulose, up to 13% of CaCO3 and/or Al(OH)3, up to 20% of propane-1,2-diol (glycol), and up to 21% of TEMPO-oxidized cotton linters were coated on the model paper, without additional adhesive. The pristine model paper and papers coated with nanofibrillated cellulose-based composite films were characterized in terms of water absorptiveness by COBB method and water drop contact angle measurements. The surface appearance was characterized by scanning electron microscopy (SEM) and surface chemistry by infrared spectroscopy with Fourier transform and attenuated total reflection (ATR-FTIR). Additionally, optical properties, i.e. measurement of reflection curves and CIE degrees of whiteness, were determined according to appropriate standards. For all papers coated with nanofibrillated cellulose-based films, depending on the composition of the dispersions, a decrease in sorption properties was achieved, without changes in optical properties and surface morphology of the paper compared to the pristine paper.

Castor Oil Based Polyurethane Nanocomposites with Cellulose Nanocrystallites Fillers

In this study the castor oil based polyurethane (PU) nanocomposites were prepared by dispersing the cellulose nanocrystallites (CNC) isolated from cotton linters. CNC was dispersed in PU matrix using ultrasonicator coupled with high shear homogenizer. The filler loading was varied from 0-10% of the total weight of the mixture. The PU/CNC nanocomposites were characterized by SEM, XRD, FTIR, mechanical and barrier properties. SEM confirmed homogeneous dispersion of CNCs in polyurethane matrix with small agglomerates at certain places. Improvement in mechanical properties was observed as compared to neat PU. Diffusivity and permeability of the nanocomposites was reduced at higher loadings of CNC.