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Single-crystalline cellulose II and α-chitin regenerated from low-molecular weight solutions using phosphoric acids as a solvent were investigated by electron diffraction together with high-resolution imaging. Cellulose II of two different degrees of polymerization (DP) were regenerated by precipitation either in water (DP = 15) or in ethanol (DP = 7), and the latter revealed better crystalline perfection...
Two kinds of band-like cellulose assemblies, coarse and densestructures, are produced in Hestrin–Schramm medium at 4 °Cusing smooth colonies isolated from Acetobacter xylinumATCC23769, whereas ribbon cellulose assemblies are produced by the samecoloniesat 28 °C. The dense and the coarse band-like assembliesconsist of many strand-like cellulose entities (‘strands’) and areextruded perpendicularly to...
13C-NMR chemical shifts were measured for C-4 and C-6 in a collection of eight crystalline glucoses and glucosides. The influence of the hydroxymethyl conformation was greater at C-4 than at C-6, with mean chemical shifts for gauche–trans molecules displaced 3.1 ppm (C-4) and 2.5 ppm (C-6) relative to gauche–gauche molecules. This information was used to interpret 13C-NMR spectra of crystalline celluloses...
The chemical shift anisotropies (CSAs) of cellulose Iα and Iβ, the two crystalline constituents of bacterial cellulose produced by Acetobacter xylinum (DSM 14666), and regenerated cellulose II are reported for each of the spectroscopically resolved carbon resonances using the phase adjusted spinning sideband (PASS) experiment. The data are compared with experimental results using the recoupling of...
The chemical shift anisotropies (CSAs) of cellulose Iα and Iβ, the two crystalline constituents of bacterial cellulose produced by Acetobacter xylinum (DSM 14666), and regenerated cellulose II are reported for each of the spectroscopically resolved carbon resonances using the phase adjusted spinning sideband (PASS) experiment. The data are compared with experimental results using the recoupling of...
The completeness of mercerisation can be evaluated by investigating the changes in the crystalline regions of cellulose from cellulose I (C-I) to cellulose II (C-II) by the X-ray powder diffraction method. Mercerisation experiments in four different solution systems: ethanol/water, acetone, DMSO and xylene, are reported. Also the effect of some additives, external pressure, treatment time and alkalisation...
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...
All-cellulose composites were prepared by partly dissolving microcrystalline cellulose (MCC) in an 8.0 wt% LiCl/DMAc solution, then regenerating the dissolved portion. Wide-angle X-ray scattering (WAXS) and solid-state 13C NMR spectra were used to characterize molecular packing. The MCC was transformed to relatively slender crystallites of cellulose I in a matrix of paracrystalline and amorphous 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%...
The aim of this work was to investigate the morphological and structural changes associated with mercerization of cellulose fibres with combined confocal Raman and atomic force microscopy (AFM). During mercerization the alkali induces a change in polymorphic lattice from cellulose I to II. This was observed by confocal Raman spectroscopy from cellulose samples treated with 10, 15 and 25% aqueous sodium...
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...
Cellulose is a linear 1,4-β-glucan polymer where the units are able to form highly ordered structures, as a result of extensive interaction through intra- and intermolecular hydrogen bonding of the three hydroxyl groups in each cellulose unit. Alkali has a substantial influence on morphological, molecular and supramolecular properties of cellulose II polymer fibres causing changes in crystallinity...
Mercerized wood cellulose was oxidized by 4-acetamide-TEMPO/NaClO/NaClO2 system at 60 °C and pH 4.8 for 1–5 days. Mostly individual nanocrystals 4–7 nm in width and 100–200 nm in length were obtained by ultrasonication of the oxidized product in water. The nanocrystals had the cellulose II structure, and carboxylate contents of 2.0–2.4 mmol/g, indicating that these carboxylate groups were selectively...
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...
Lysozyme was attached through an amide linkage between some of the protein’s aspartate and glutamate residues to amino-glycine-cellulose, which was prepared by esterification of glycine to preparations of cotton nanocrystals. The nanocrystalline preparations were produced through acid hydrolysis and mechanical breakage of the cotton fibers from a scoured and bleached cotton fabric and a scoured and...
In this study the effect of the mercerization degree on the water retention value (WRV) and tensile properties of compression molded sulphite dissolving pulp was evaluated. The pulp was treated with 9, 10, or 11 % aqueous NaOH solution for 1 h before compression molding. To study the time dependence of mercerization the pulp was treated with 12 wt% aqueous NaOH for 1, 6 or 48 h. The cellulose I and...
Well-dispersed cellulose II nanofibers with high purity of 92 % and uniform width of 15–40 nm were isolated from wood and compared to cellulose I nanofibers. First, ground wood powder was purified by series of chemical treatments. The resulting purified pulp was treated with 17.5 wt% sodium hydroxide (NaOH) solution to mercerize the cellulose. The mercerized pulp was further mechanically nanofibrillated...
We have modified the standard sulphuric acid hydrolysis method for the production of cellulose nanocrystals (CNCs) to successfully isolate a novel, highly crystalline cellulose material from the spent liquor of CNCs. The novel material has a cellulose II crystal structure that is distinctly different from the cellulose I crystal structure of CNCs. The modified method uses a shorter time for the hydrolysis,...
Since periodate oxidation selectively creates (masked) aldehyde groups that can serve as anchors for further modification steps, this method is suitable for modifying and functionalizing cellulose. Although numerous studies deal with that topic, there are still knowledge gaps regarding periodate oxidation. In our study, we focused on examining how the type of cellulose allomorph influences the reaction...
It is well known that there are two crystal types for a cellulose/water complex: Na–cellulose IV and cellulose II hydrate. The water molecules in these crystals are released with increasing temperature and the hydrated models are then transformed into cellulose II crystals. Dehydration can be observed even when the cellulose/water crystal is soaked in water. In this study, we investigated the dehydration...
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