The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The splitting tendency of viscose and modal fibers in aqueous alkali solutions of LiOH, NaOH, KOH and TMAH was investigated. The viscose fibers splitted up to 5–7 fibrils, whereas modal fibers splitted up to 2–4 fibrils depending on alkali type and concentration. The fibrillar structure of lyocell enables it to split more (15–20 fibrils) than viscose and modal fibers. Splitting occurs where internal...
Cellulose multi-filament fibers have been spun successfully on a pilot plant scale, from a cellulose dope in 7 wt% NaOH/12 wt% urea aqueous solution pre-cooled to −12 °C. Coagulation was accomplished in a bath with 10 wt% H2SO4/12 wt% Na2SO4 and then 5 wt% H2SO4 aqueous solution. By using different finishing oil, including H2O, 4% glycerol aqueous solution, 2% polyvinyl alcohol (PVA) aqueous solution,...
Structure and properties for binary blends composed of biomass-based cellulose acetate propionate (CAP) and poly(epichlorohydrin) (PECH) have been studied. It is found from the dynamic mechanical measurements that mutual dissolution takes place to some degree with remaining CAP-rich and PECH-rich regions in the blends. As a result of the interdiffusion, leading to fine morphology, the blends exhibit...
The influence of the modification of cellulose fibres by the imidazolidinone derivative 1,3-dimethyl-4,5-dihydroxyethylene urea (DMeDHEU) on fibre surface free energy and electrochemical potential was studied. The presence of DMeDHEU in the cellulose structure was confirmed by infrared spectral analysis. The surface free energy of untreated and treated cellulose fibres was determined from the results...
The swelling and dissolution mechanisms of several cellulose derivatives (nitrocellulose, cyanoethylcellulose and xanthate fibres) are studied in aqueous systems (N-methylmorpholine-N-oxide—water with various contents of water, hydroxide sodium—water) and in ionic liquids. The results are compared with the five modes describing the swelling and dissolution mechanisms of cotton and wood cellulose fibres...
In this work a study on the feasibility of extracting cellulose from sisal fiber, by means of two different procedures was carried out. These processes included usual chemical procedures such as acid hydrolysis, chlorination, alkaline extraction, and bleaching. The final products were characterized by means of Thermogravimetric Analysis (TGA), Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD),...
We prepared from cellulose fibres monolithic aero- and cryogels. Cellulose is dissolved in hydrated calciumthiocyanate melt, gelled, aged and dried by several methods. The density of cellulose aerogels produced by supercritical drying is in the range between 10 and 60 kg/m3 with a surface area of 200–220 m2/g. The cellulose cryogels produced by freeze drying exhibit a maximum surface area of 160 m...
Microfibrillated cellulose from purified sugar beet pulp was converted into cellulose III by immersion in liquid ammonia. When freed from ammonia, this product was oxidized in water at pH-10 using NaBr, NaOCl and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) under various conditions and concentrations. The resulting water-soluble cellouronic acid—i.e. cellulose oxidized at the C6 position-...
Bacterial cellulose (BC), which is produced by Gluconacetobacter xylinus (Ga. xylinus) in culture, is made up of a three-dimensional network of ribbon-shaped bundles of cellulose microfibrils. In the current studies, we used two processes to prepare nanocomposites of BC filled with silica particles. In Process I, Ga. xylinus was incubated in medium containing silica sol Snowtex 0 (ST 0, pH 2–4) or...
Fourier transform infrared (FTIR) spectroscopic imaging was used to study the initial diffusion of different solvents in cellulose acetate butyrate (CAB) films containing different amounts of acetyl and butyryl substituents. Different solvents and solvent/non-solvent mixtures were also studied. The FTIR imaging system allowed acquisition of sequential images of the CAB films as solvent penetration...
Orange mesocarp was obtained after removal of the epicarp and the endocarp from oranges. It was dried, pulverized and digested with 2% w/v sodium hydroxide at 80°C for 3 h. Alpha- and micro-crystalline celluloses were extracted from the pulp using 17.5% w/v and 2.5 N hydrochloric acid, respectively. The physicochemical and powder properties of the extracted material were evaluated. Results obtained...
Different paper-grade pulps were extracted with nitren, NaOH and KOH in order to produce dissolving pulps and polymeric xylan. The yield and structure of the isolated nitren and alkali xylans were investigated by carbohydrate analysis, HPSEC and 1H-NMR spectroscopy. In addition the effect of washing stages on the residual nickel content of the nitren xylans was investigated. By nitren extraction up...
The molecular and physical structures of cellulosic rayon fiber during the stepwise heat treatment for the fabrication of activated carbon fiber (ACF) were researched by Fourier transform infrared spectroscopy, wide angle X-ray diffraction and elemental analysis. Dibasic ammonium phosphate (DAP) lowers the dehydration temperature of rayon evidently and acts also as a reactant besides as a catalyst...
Microfibrillated cellulose (MFC) was prepared by disintegration of bleached softwood sulphite pulp through mechanical homogenization. The surface of the MFC was modified using different chemical treatments, using reactions both in aqueous- and organic solvents. The modified MFC was characterized with fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission...
Raw and refined flax, hemp, abaca, sisal, jute and ramie fibres are dipped into N-methylmorpholine N-oxide (NMMO)–water with various contents of water and into hydroxide sodium (NaOH)–water. The swelling and dissolution mechanisms of these plant fibres are similar to those observed for cotton and wood fibres. Disintegration into rod-like fragments, ballooning followed or not by dissolution and homogeneous...
In the last years several composites and high performance materials with woody and non-woody natural fibers have been developed. In this study, a morphological study of agricultural residues as rachis from Musaceae plants cultivated in Colombia has been carried out. Fibrous structures as fiber bundles, elementary or ultimate fibers and even cellulose microfibrils grouped together into microfibril...
Cellulose valerate (CV)/poly(ε-caprolactone) (PCL) blends were investigated to clarify the effect of the degree of substitution (DS) of the cellulose ester component on the miscibility. CVs of DS > 2.15 were miscible with PCL in their amorphous states, as judged from the detection of a single Tg by differential scanning calorimetry (DSC). This result and other complementary data for cellulose...
The dissolution of cellulose in different ionic liquids will be described as a very recent subject for a direct dissolving process, which was used to prepare regenerated cellulose fibres. The preparation of the dopes was arranged starting from slurry of cellulose in the aqueous ionic liquid by removing the water at elevated temperature, vacuum and high shearing rates. As ionic liquids, the 1-N-Butyl-3-methylimidazolium...
The efforts of US congress to encourage the use of biofuels to reduce its dependency on petroleum have recently been endorsed by the President. This will inevitably turn the spotlight back on to cellulosic ethanol as an alternative fuel with a lower carbon footprint. Biofuels are currently only truly economic to produce in times of petroleum shortage, but the development of cheaper enzymes and better...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.