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.
Functional thiomethyl and thiosulfate derivatives of carboxymethylcellulose (CMC, DS = 0.9) were synthesized by nucleophilic displacement reactions. Alkylation of CMC by allyl glycidyl ether took mainly place at the primary positions of the cellulose backbone and yielded a 6-O-(3′-allyloxy-2′-hydroxypropyl)-CMC 1 with a partial DS of 3′-allyloxy-2′-hydroxypropyl substituents DSallyl of up to 0.43...
The research presented herein is the first attempt to probe the chemical nature of lignocellulosic samples by the application of carbon near edge X-ray absorption fine structure spectroscopy (C-NEXAFS). C-NEXAFS is a soft X-ray technique that principally provides selective interrogation of discrete atomic moieties using photoelectrons of variable energies. The X1A beam line of the National Synchrotron...
For solutions of cellulose (Solucell, Mw=230 kg mol−1) in the mixed solvent DMAc (N,N-dimethylacetamide) + LiCl, it is demonstrated by means of an electrolysis cell, subdivided into six compartments, that cellulose migrates to the anode. This observation is interpreted in terms of a field-induced opening of associations between the [DMAc]xLi+ complex and the [cellulose]Cl− complex. This understanding...
Dilute acid hydrolysis of pulps was studied by following the decrease in intrinsic viscosity of preparations of microcrystalline cellulose. The decrease in intrinsic viscosity and the loss of weight during hydrolysis at reaction temperatures of 60 and 80 °C was investigated, using acid concentrations from 0.5 to 4 M and two different acids (HCl and H2SO4). The same levelling-off degree of polymerisation...
The basic strategy to make a well-defined A-block-B type cellulose derivative consisting of cellulose and a hydrophobic part was established. The model experiments using cellobiose derivatives play an important role in an actual synthesis of A-block-B type copolymer consisting of cellulose and a hydrophobic part with well-controlled length. A new hydrophobic building block, 15-azidopentadecanoyl chloride,...
Cellulose has been deformed plastically by the use of mechanical shear, uniaxial pressure, and laser radiation. Felty specimens either from wood pulp or cotton wool were converted to thin compact transparent disks. Afterwards, the disks were examined by IR-spectroscopy, light microscopy, and scanning electron microscopy. This novel approach may pave the way for a new method to convert natural cellulose...
Various cellulose and pulp samples including softwood bleached kraft pulp (SBKP) were dissolved in 8% lithium chloride/1,3-dimethyl-2-imidazolidinone (LiCl/DMI) and 8% LiCl/N,N-dimethylacetamide (DMAc), and the obtained solutions were subjected to size-exclusion chromatographic analysis with multi-angle light scattering detection (SEC-MALLS). Although SBKP was not completely soluble in 8% LiCl/DMAc,...
The performance of electrorheological (ER) fluids containing cellulose particles dispersed in lubricating oil was investigated as a function of particle water content, DC electric field strength, particle concentration, and temperature. Over a range of applied electric fields (0–3 kV/mm), yield stress was observed to increase with increasing cellulose moisture content up to 8.5 wt% followed by a decrease...
The Lyocell process is a modern ‘green’ industrial fiber-making technology, which employs N-methylmorpholine-N-oxide monohydrate (NMMO) to directly dissolve cellulose. One problem in Lyocell processing is the discoloration of the spinning dope due to chemical side reactions. Two different methods were elaborated to isolate chromophores, which are present in minute amounts only, from Lyocell fibers,...
Thin layers of cellulose I nanocrystals were spin-coated onto silicon wafers to give a flat model cellulose surface. A mild heat treatment was required to stabilize the cellulose layer. Interactions of this surface with polyelectrolyte layers and multilayers were probed by atomic force microscopy in water and dilute salt solutions. Deflection–distance curves for standard silicon nitride tips were...
This study investigates the fundamental topochemical effects of dielectric-barrier discharge treatment on bleached chemical pulp and unbleached mechanical pulp fiber surfaces. Fibers were treated with various levels of dielectric-barrier discharge treatment ranging from 0 to 9.27 kW/m2/min. Changes to the fiber surface topochemistry were investigated by atomic force microscopy (AFM). The AFM studies...
An industrial calcium sulfite pulp was fractionated in a hydrocyclone to four fractions that differed in dimensions and composition due to differences in density. The intention was to investigate whether the fibre dimensions had any influence on the properties of carboxymethyl cellulose (CMC) produced from the fractions and especially how the properties of the unreacted material differed. It was surprisingly...
The sorption of xyloglucan (XG) on cellulose is a basic feature of the supramolecular assembly of plant cell walls. The binding to cellulose of xyloglucan fractions from Rubus fruticosus suspension-cultured cells with different substitution patterns was assayed on celluloses having various degrees of crystallinity between 20 and 95%. The primary structure of XGs differing in their Xyl/Glc ratio affected...
The fibrillation tendencies of various cellulosic fibers in aqueous solution containing alkali metal hydroxide and ethanol were evaluated with two specific parameters: the critical point of fibrillation (CPFconc.), that is a concentration of swelling agent where the fibrillation begins, and the ratio of initial increase in fibril number to increase in concentration of swelling agent (Ii). The CPF...
The influences of temperature, concentration of swelling agents and fiber materials on the fibrillation tendency in various cellulosic fibers in aqueous solutions were investigated in terms of fibrillation stability and fibrillation sensitivities to alkali and heat. The fibrillation stability and the fibrillation sensitivity to swelling agents were evaluated with a critical point of fibrillation (CPF...
Linter cellulose was suspended in water and oxidized by the NaClO/NaBr/2,2,6,6-tetramehylpiperidine-1-oxy radical (TEMPO) system at pH 10.5 (TEMPO-mediated oxidation), and the oxidized products were separated into several fractions by filtration and centrifugation, depending on their particle sizes and apparent water-solubility. The major fraction (>ca. 80 mass % of the original linter cellulose)...
This communication reports the detailed procedure for the cleavage of cellulose triacetate (30 g scale) with pivalic anhydride and boron trifluoride etherate in dichloromethane (pivaloylysis). With this mild and efficient method the cellulose oligomers up to the octasaccharide can be obtained in gram scale. Full characteristic data of this compounds are given.
The amount of disordered material in two types of hardwood kraft pulps was estimated by determining the weight loss at the point where the levelling-off degree of polymerisation (LODP) was reached. The pulps used were commercial pulps viz (1)one conventional birch kraft and (2)one mixed hardwood (MHW) kraft pulp that had been prehydrolysed prior to cooking. The results indicated that the hemicellulose...
A Raman crystallinity index – XcRaman – characterizing the degree of crystallinity of partially crystalline cellulose I samples was created, utilizing the crystallinity dependence of CH2 bending modes. For calibration, physical mixtures containing different mass fractions of crystalline cellulose I and its amorphous form were prepared. Crystallinities from 0 to 60% were generated. Relative intensity...
Cellulose chains in bio-system were examined. A model system, in which molecular chains were fixed at one end in an aqueous environment, was analyzed as a model bio-system of cellulose. Five cellulose chains (DP = 40), whose one end was fixed (like a cantilever), were placed in 20.0 × 2.8 × 2.8 nm3 cell which was filled up with water molecules. This model cell was thoroughly annealed and then piled...
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.