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Dissolution of a number of cellulose samples in aqueous NaOH was investigated with respect to the influence of molecular weight, crystalline form and the degree of crystallinity of the source samples. A procedure for dissolving microcrystalline cellulose was developed and optimized, and then applied to other cellulose samples of different crystalline forms, crystallinity indices and molecular weights...
The kinetics of the TEMPO-mediated oxidation of regenerated celluloses has been studied. It is revealed that the oxidation reaction of the regenerated celluloses by the 2,2,6,6-tetramethyl-piperidine-1-oxyl radical (TEMPO)–NaBr–NaOCl system can be approximately described by first-order kinetics with respect to substrate. In the concentration range used the rate constant k is directly proportional...
The kinetics of the TEMPO-mediated oxidation of regenerated celluloses has been studied. It is revealed that the oxidation reaction of the regenerated celluloses by the 2,2,6,6-tetramethyl-piperidine-1-oxyl radical (TEMPO)–NaBr–NaOCl system can be approximately described by first-order kinetics with respect to substrate. In the concentration range used the rate constant k is directly proportional...
Synchrotron X-ray data have been collected to 1.4 Å resolution at the NE-CAT beam-line at the Advanced Photon Source from fibers of cellulose Iβ and regenerated cellulose II (Fortisan) at ambient temperature and at 100 K in order to understand the effects of low temperature on cellulose more thoroughly. Crystal structures have been determined at each temperature. The unit cell of regenerated cellulose...
Three groups of cellulose II samples, 20% NaOH-treated native celluloses (M-native celluloses), commercial regenerated celluloses and those treated with 20% NaOH (M-regenerated celluloses), were subjected to dilute acid hydrolysis at 105 °C to obtain so-called leveling-off degrees of polymerization (LODP). Molecular mass parameters of the acid-hydrolyzed products were analyzed by SEC-MALLS using 1%...
Various cellulose II samples, ball-milled native celluloses and ball-milled wood saw dust were subjected to 2,2,6,6-tetramethypyperidine-1-oxyl radical (TEMPO)-mediated oxidation to prepare cellouronic acid Na salts (CUAs). The TEMPO-oxidized products obtained were analyzed by 13C-NMR and size-exclusion chromatography (SEC). When the cellulose II samples with degrees of polymerization (DP) of 220–680...
To understand the effect of alkali pre-treatment on the dyeing of lyocell fabrics, samples are pre-treated with 0.0–7.0 mol dm−3 NaOH using a pad-batch process and then dyed with different types of reactive dyes. Exhaustion, fixation, and visual colour strength (K/S values) are measured. It is observed that sodium hydroxide pre-treatment significantly improves the colour yield, exhaustion, and fixation...
A self-reinforced cellulosic material was produced exclusively from regenerated cellulose microcrystals. The level of reinforcement was controlled by tailoring the crystallinity of cellulose by controlling the dissolution of microcrystalline cellulose (MCC) before its regeneration process. After the cellulose regeneration a self-reinforced material was obtained in which cellulose crystals reinforced...
Zinc oxide (ZnO) nanoparticles were immobilized on the surface of regenerated cellulose films by a wet chemical method in which the controlled hydrolysis of a Zn(II)-amine complex leads to the formation of ZnO nanoparticles. Cellulose-ZnO materials were characterized by spectral, thermal and optical methods. Scanning electron microscope and atomic force microscope analyses confirmed the formation...
A softwood bleached kraft pulp (SBKP) and cotton lint cellulose were fully or partially mercerized, and these along with celluloses and commercially available regenerated cellulose fiber and beads were oxidized by 4-acetamido-TEMPO/NaClO/NaClO2 at 60 °C and pH 4.8. Weight recovery ratios and carboxylate contents of the oxidized celluloses were 65–80% and 1.8–2.2 mmol g−1, respectively. Transparent...
Transparent and water repellent gas barrier cellulose films were fabricated by surface modification of alkali/urea regenerated cellulose (AUC) films by soaking in cationic alkylketene dimer (AKD) dispersion, drying, and heating. Highly water repellent and excellent gas barrier properties were obtained for AKD-treated and heated AUC films due to covering of the film surfaces by hydrophobic AKD components...
The structure of microbial cellulose (MC) produced by Acetobacter xylinum was studied in presence of Fluorescent Brightener, Direct Blue 1, 14, 15, 53, Direct Red 28, 75 and 79, as probe. X-ray diffraction pattern of the product showed that it was a crystalline complex of dye and cellulose. The product has the structure in which the monomolecular layer of the dye molecule is included between the cellulose...
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...
In this paper the influence of charged species on the sheet strength of viscose fibres was investigated. Four samples of chemical modified viscose fibres, as well as a reference fibre were studied. The swelling of these viscose fibres and the breaking length of hand sheets have been determined. Comparing the results, the influence of both, swelling and surface charge on the bonding force, is evident...
Regenerated cellulose scaffolds with an aligned, columnar and open porosity were fabricated by an ice-templating process. For this purpose, cellulose dissolved in the non-derivatizing aqueous solvent NaOH/urea was used. This cellulose solution was frozen from the bottom side of the mold leading to a directional heat flow in only one direction. Consequently, the directional solidification leads to...
The cellulose electro-active paper (EAPap) has been discovered as a smart material that can be used for sensors, actuators and flexible electronics. EAPap is made from regenerated cellulose that requires dissolving cellulose pulp using solvents with a heating process. However the heating process in dissolving cellulose is very critical to the performance of EAPap. In this paper, we introduce...
The degree of polymerisation (DP), is an important polymer property which has a direct influence on the mechanical properties such as tensile strength. Here we measure the degree of polymerisation of regenerated cellulose dissolved in the ionic liquids 1-butyl-3-methylimidazolium acetate (BMIMOAc) and 1-allyl-3-methylimidazolium chloride (AMIMCl), at different dissolution temperatures, times and coagulants...
Formation of regenerated cellulose (RC) membranes from dimethyl sulfoxide and paraformaldehyde solvent system is described. These membranes were cast. on cylindrical molds using the dip coating approach. After dip coating, the molds were immersed in water, acetone and several short chain 1-alkanols to precipitate cellulose. The wet cast. membranes were then thermally treated to obtain rigid, solvent...
The structure formation of regenerated cellulose from aqueous sodium hydroxide solution was investigated using synchrotron X-ray radiation. The diffraction shoulder, which was possibly assigned to the molecular sheet structure, was observed in the wide angle scattering region during the gelation process of the solution. Molecular sheets were progressively piled to more than three layers at the final...
Cellulose carbamate (CC) prepared using microwave irradiation was reinforced with graphene oxide (GO) to fabricate homogeneous and highly ordered CC–GO membranes using a simple solution-mixing method. The effect of GO content on the properties of the membranes was investigated. Atomic force microscope and transmission electron microscope images indicated that the self-synthesized GO nanosheets exhibited...
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