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Electrokinetic tests, based on the streaming potential method, were used to elucidate interactions between cationic polyelectrolytes and cellulosic fibers and to reveal aspects of fibers’ nanoporosity. The fibrillated and nanoporous nature of bleached kraft fibers gave rise to time-dependent changes in streaming potential, following treatment of the wetted fibers with poly-diallyldimethylammonium...
Bacterial cellulose (BC) films with different porosities have been developed in order to obtain improved mechanical properties. After 13 days of incubation of Gluconobacter xylinum bacteria in static culture, BC pellicles have been set. BC films have been compression molded after water dispersion of BC pellicles and filtration by applying different pressures (10, 50, and 100 MPa) to obtain films with...
In the frame of this work, cellulose microbeads with an average particle size of 2.3 μm were characterized with respect to porosity using a batch solute exclusion method and two groups of model substances, namely proteins and polystyrene sulfonates. The pores of the microbeads were almost completely accessible to proteins with Stokes radii below 2.5 nm. More than 60% of the pores were accessible to...
Due to the high potential of cellulose nanoparticles in composite materials and for both fundamental and technological considerations, we investigated the interaction between microfibrillar cellulose and fibers. The contribution to the paper properties of fines added to a pulp suspension was determined. The impact of various proportions of fines added to a softwood kraft pulp on the paper strength...
Composites made of inorganic filler particles and cellulose nanofibres can be applied as substrates for printed electronics. We have studied the structural properties of these substrates both experimentally and with particle-level modeling approach. Our model describes the skeleton structure formed by pigment particles of varied shapes and size distributions. Nanocellulose is assumed to fill voids...
In this study the effects of altering the coagulation medium during regeneration of cellulose dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate, were investigated using solid-state NMR spectroscopy and NMR cryoporometry. In addition, the influence of drying procedure on the structure of regenerated cellulose was studied. Complete conversion of the starting material into regenerated...
The porosity of lignocellulosic materials is a key feature for the enzymatic hydrolysis of the constituent polysaccharides, being affected by its drying and lignin content. Here we evaluated the influence of both parameters in the porosity of sugarcane bagasse, using raw and chlorite-delignified samples. A fraction of these samples was air dried at room temperature and the remainder one was kept wet...
To improve the rehydration ability of bacterial cellulose (BC), many macromolecules have been used as modifiers in previous reports. However, the aggregation of additives in the BC matrix appears to be inevitable. We investigated different parts of a BC pellicle, which was achieved by in situ modification with carboxymethyl cellulose (CMC) in culture with Gluconacetobacter xylinus ATCC53582 or Enterobacter...
Dissolving grade pulps are used as raw material for manufacture of regenerated cellulose fibres and their use is constantly growing. Despite intensive research, there is still a need to develop cellulose dissolution-regeneration processes that would be economically viable, fulfil the pre-conditions of sustainability and would be able to meet the strict product quality requirements. The basis for creation...
As a result of the constantly growing demand for textile fibres interest in utilising cellulose pulps for manufacturing regenerated cellulose fibres is growing. One promising water-based process for the manufacture of regenerated cellulosic products is the Biocelsol process based on an NaOH/ZnO solvent system. The drawback of the Biocelsol process is the need for pre-treatment of the pulp, i.e. long...
Dissolving pulps are used to manufacture various cellulose derived products through cellulose dissolution. Solubility of cellulose pulp has been claimed to be strongly dependent on the porosity development, the degree of polymerisation and the pulp viscosity. The removal of external cell walls has been proposed to have a key role in the pulp solubility. In this paper, the effect of the outermost surface...
Flax and hemp fibres were treated by various combinations of water/diluted alkaline solution and stirring/ultrasound, respectively. Changes in the microstructure (scanning electron microscopy) and porous structure (low-temperature nitrogen adsorption), removal of non-cellulosic materials (weight loss, FTIR), mean fibre diameter, and adhesion of the polypropylene matrix to the fibres (micro-bond test)...
Highly porous, lightweight versatile cellulose materials were prepared via dissolution–coagulation and subsequent various drying routes. Cellulose was dissolved in ionic liquid/DMSO mixture and coagulation was performed in ethanol. The as prepared wet precursors were used to make materials with three different drying methods: supercritical CO2 drying, freeze-drying and vacuum drying. The influence...
Papers are mostly made with lignocellulose and additives among which calcium carbonate has a primarily importance. Calcium carbonate as a filler provides specific properties to the paper like brightness, porosity, etc. Because of low retention, calcium carbonate remains in large quantities in the waste water when at the final stage, the paper is couched and pressed. It is therefore interesting to...
Flexible nanocellulose composites with silica nanoparticle loading from 5 to 77 wt% and tunable pore size were made and characterised. The pore structure of the new composites can be controlled (100–1000 nm to 10–60 nm) by adjusting the silica nanoparticle content. Composites were prepared by first complexing nanoparticles with a cationic dimethylaminoethyl methacrylate polyacrylamide, followed by...
In an attempt to prepare cellulose nanocrystals (CNCs) by TEMPO-mediated oxidation of microcrystalline cellulose (MCC), a new species of MCC called AaltoCell was placed under scrutiny. Unlike Avicel, AaltoCell is a never-dried species, still containing ca. 10% xylan in its structure. According to thermoporosimetry, the pore size distributions of AaltoCell and Avicel did not differ from each other...
This study compares the characteristics of cellulose nanocrystal (CNC) agglomerates prepared using spray drying, freeze drying, and spray freeze drying. Moreover, the effect of the concentration of CNC in the initial aqueous dispersion (~ 0.5–10.0 wt%) on the morphology, particle size distribution, porosity and crystalline structure of the spray freeze dried CNC agglomerates were investigated. Scanning...
Unlike many mineral-based insulation materials bio-based lignocellulosic fibre and shiv offer a number of benefits including thermal and hygroscopic properties. The microstructure, porosity and chemical compositions of the plant cell walls play a major role in the moisture exchange process. In this paper, the effects of microstructure, chemical composition, porosity and pore size distribution of both...
In this study, a gradually increased hydro-mechanical treatments duration were applied to native hemp bast fibres with a traditional pulp and paper beating device (laboratory Valley beater). There is often a trade-off between the treatment applied to the fibres and the effect on their integrity. The multimodal analysis provided an understanding of the beating impact on the fibres at multiple scales...
We propose a new method for determining the surface energy of paper and its components using the contact angle technique. Calendered sheets and model liquids were used in this study. A rapid evolution of the probe/handsheet contact angle with time was observed for all tested conditions. A suitable method for choosing the contact angle and a new model to determine the surface energy and its components...
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