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It has been shown, in the present investigation, that the two methods used to investigate the pore size distribution of unbleached chemical pulps, i.e. inverse size exclusion chromatography (ISEC) and nuclear magnetic resonance (NMR), give different average pore radius for the pores inside the fibre wall. This is due to the way in which these experiments are performed and the sensitivity of the methods...
The swelling behavior of lyocell fiber in alkali solutions and the alkali uptake were investigated as well as their influences on the reaction of sodium-hydroxy-dichlor-triazine with lyocell. The uptake of NaOH was increased from 0.69 mmol/g up to 4.63 mmol/g, leading to the enhancement of fiber swelling from 1.01 cm3/g to 2.34 cm3/g when alkali concentration in preliminary alkali treatment was increased...
Bi-functional reactive dyes have been used for reducing the fibrillation of lyocell fibres. The sole influence of CI Reactive Black 5 dye on the fibrillation tendency of lyocell single jersey knitted fabrics was investigated by dyeing with different concentrations (35 g/L for medium shade and 70 g/L for dark shade), dyeing without dyestuff and by decolouration process after each dyeing. The fibrillation...
Hydroxypropylmethylcellulose and Poly (vinyl alcohol) blend microspheres were prepared by water in oil emulsion method and Ciprofloxacin Hydrochloride (CFHcl) was loaded into the interpenetrating polymer network (IPN) microspheres that are crosslinked with glutaraldehyde (GA). Blend microspheres were characterized using Fourier transform infrared Spectroscopy (FT-IR), Scanning electron microscopy,...
Crosslinking of cellulose fibres was obtained by inducing a substitution reaction in a cationic cellulose ether (NMM-cellulose) prepared by action of N-oxiranylmethyl-N-methylmorpholinium chloride. During the reaction the N-methylmorpholine moiety of the cellulosic ether acts as a leaving group facilitating a covalent bond formation between the ether substituent and a hydroxyl or other nucleophilic...
The study on bacterial cellulose (BC) nanofibers used as templates for hydroxylapatite (HAp) deposition has been investigated by our group and many other researchers. However, BC is only microscopically similar to natural collagen but not molecular structure. If protein could be introduced to the surfaces of BC nanofibers, the BC nanofibers could mimic the natural collagen fibers in terms of both...
Nanofibrillated cellulose (NFC) was compounded with poly(acrylic acid) (PAA) via solvent casting. Nanocomposite films were thermally-crosslinked to allow the formation of ester bonds between NFC and PAA, as confirmed by 13CNMR and infrared spectroscopy. The network morphology of the cellulose nanofibrils was left intact by the introduction of PAA and crosslinking. Water absorption and swelling was...
The polyaromatic structure of lignin has long been recognized as a key contributor to the rigidity of plant vascular tissues. Although lignin structure was once conceptualized as a highly networked, heterogeneous, high molecular weight polymer, recent studies have suggested a very different configuration may exist in planta. These findings, coupled with the increasing attention and interest in efficiently...
Simultaneous crosslinking and cationization of cotton cellulose were carried out by using two dialdehydes, glyoxal (GO) and glutaraldehyde (GA), along with choline chloride (ChCl). Two heating methods, conventional pad-dry-cure (PDC) and microwave irradiation, were investigated and compared. The results revealed that two aldehyde molecules reacted very differently in the presence of ChCl under two...
Hydrogels with high water uptake were prepared by ionizing radiation induced crosslinking in aqueous solutions of four cellulose derivatives (carboxymethylcellulose sodium salt—CMC-Na, methylcellulose—MC, hydroxyethylcellulose—HEC and hydroxypropylcellulose—HPC). The gel fraction increased with absorbed dose, while water uptake decreased. At high polymer concentrations lower gel fractions were found...
Cellulose nanofibrils (CNF) form hydrogels at low concentrations. These hydrogels are held together by transient interactions such as entanglement of fibrils, non-specific ionic interactions and hydrogen bonds; and are thus vulnerable for changes in the chemical environment or the influence of mechanical forces. By a covalent crosslinking of the fibrils, stable permanent gels can be formed. In this...
Chitosan film with nanocrystalline cellulose (NCC) as a physical reinforcement and tannic acid as a chemical crosslinker was prepared by the casting evaporation method. The objective was to improve its mechanical properties, reduce its moisture content and solubility, and maintain its biodegradability. This was done to examine its potential suitability as an ultra-lightweight wing membrane for a future...
Hydroxypropylmethyl cellulose (HPMC) samples with varying degrees of substitution of methoxy groups (DS), mass molar substitutions of hydroxypropoxy groups (MS) and molecular weights were crosslinked with citric acid to create water insoluble films with mean thickness from (48 ± 3) µm to (127 ± 8) µm. The samples presented DS ranging from 1.5 to 2.1, MS ranging from 0.25 to 0.9 and average molecular...
This study investigated the possibility of substituting petroleum-based polymers with biopolymers for films and paper coatings. Arabinoxylan (AX) was extracted from distillers’ grains, a low-value corn ethanol byproduct, and modified through crosslinking with glutaraldehyde (GA) which was made into films and paper coatings. The effects of degree of substitution (DS) on film and coating properties...
Poly(vinyl alcohol) (PVA) foams reinforced with cellulose nanocrystals (CNCs) were prepared with formaldehyde as a crosslinking agent. Two initial reaction times (10, 120 s) and the addition of CNCs (0–2 wt% based on total reaction suspension) were found to affect the foam density, water uptake, morphology and mechanical properties. A longer initial reaction time resulted in higher mechanical properties...
In this communication, we introduce a chitosan polymer gel ionic actuator with dilute acid as electrolyte solution replacing ionic liquid. Interestingly, the switch not only produces obvious improvements in actuation performance, but the actuator bends towards the opposite direction. It presents a cathode deflection phenomenon instead of the usual anode deflection. Moreover, ion channels inside the...
Semi-interpenetrating polymer network hydrogels with improved mechanical properties and remarkable sensitivity toward pH changes were prepared using chitosan reinforced with cellulose nanocrystals (CNCs). Glutaraldehyde was used as a crosslinker because of its high reactivity toward the amine groups of chitosan. In this study, rod-shaped CNCs that were approximately 200–300 nm in length and 40–50 nm...
Durable press finishing is a common process used to impart wrinkle-free properties to cotton fabrics through the crosslinking of cellulose macromolecules. Unfortunately, this process results in a loss of fabric strength and decreases the durability of garments. If the content of crosslinked fibers is reduced in the fabrics, their strength would be retained to a greater extent. In addition, hydrophilic...
Lyocell fabrics were pretreated with NaOH, KOH and LiOH and subsequently crosslinked with three urea–formaldehyde based crosslinkers DMDHEU, DMeDHEU and DMU. The mechanical properties varied with the alkali concentration in fabrics crosslinked after pretreatment with 2–8 mol/l NaOH and 4 mol/l LiOH. In fabrics crosslinked after pretreatment with 2–8 mol/l KOH and 1–3 mol/l LiOH, in contrast, the mechanical...
Crosslinked cellulose-chitosan beads were obtained via dissolution-regeneration of cellulose and chitosan by a LiOH/urea aqueous solution, followed by the crosslinking of chitosan via dialdehyde cellulose (DAC). This crosslinking reaction involved the Schiff base formation between the aldehyde groups of DAC and the amino groups of chitosan and subsequent reduction. DAC was prepared through periodate...
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