Heterogeneous acetylation of microfibrillated cellulose (MFC) was carried out to modify its physical properties and at the same time to preserve the morphology of cellulose fibrils. The overall reaction success was assessed by FTIR together with the degree of substitution (DS) defined by titration and the degree of surface substitution (DSS) evaluated by means of XPS. Dynamic contact angle measurements confirmed the hydrophobicity improvement relative to non-modified samples. The increase of contact angle upon reaching a certain reaction time and some decrease following the further acetylation was confirmed. Mechanical properties of MFC films made from chemically modified material were evaluated using tensile strength tests which showed no significant reduction of tensile strength. According to SEM images, dimension analysis and tensile strength data, the acetylation seemed not to affect the morphology of cellulose fibrils.

TEMPO-oxidized cellulose nanofibers (TOCN) were obtained from commercial Norway spruce and mixed Eucalyptus cellulose pulps using TEMPO/sodium bromide (NaBr)/sodium hypochlorite (NaClO) system at pH 10 and 22°C. After reaction, the fibrillated TEMPO-oxidized celluloses were used for preparation of self-standing films and casting of laminate films on 50 lm thick polyethylene terephthalate. Significant differences between N. spruce and Eucalyptus TOCN were registered. The tensile strength of the films showed a maximum value for spruce samples oxidized with addition of 10 mmol g -1 of NaClO. Oxygen permeability decreased with increasing oxidation levels, being lower for N. spruce TOCN compared to Eucalyptus.

2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibers were prepared from two kraft pulps (Norway spruce and mixed eucalyptus) using the TEMPO/NaBr/NaClO system at pH 10 and 22°C. After reaction and mechanical treatment, the TEMPO-oxidized celluloses were used for preparation of self-standing films and coatings of laminate films on 50-lm-thick polyethylene terephthalate films. Characterization of the films was performed based on water contact angle measurements, laser profilometry, scanning electron microscopy, and field-emission scanning electron microscopy. The purpose of this study is to understand how the measured contact angles are affected by the film's physical properties (morphology, thickness, density, and roughness).

The current work is based on experimental viscosity and compositional data of about 200 crude oil samples from various part of Russia and Norwegian continental shelf. Data analyses were performed to estimate correlations between viscosity and density values, as well as concentrations of main components from the crude oils of different origin. It appeared that in some cases it is possible to establish a general correlation of viscosity increase along with growing asphaltene, resin, and aromatics contents, but also a decrease in viscosity with increasing saturates content. The spread of the data points can be rather wide for the oils of different origin. It was observed that asphaltenes from all the crude oil samples acted as promoters of the viscosity growth at rather low concentrations, while resins and aromatics effectively increased viscosity in higher concentration range. The effect of asphaltenes on the viscosity of real crude oils seems to be more important than when dissolved in a model solvent (xylene). This means that either the asphaltenes have a different solvation state in crude oils compared to xylene, or asphaltenes are not solely responsible for the high viscosity of the crude oils.