•Novel Na-ionic conductor based on alkali-cellulose was recognized.•The insertion of Na-ion in cellulose improved its electrical behavior.•The alkali-cellulose and its precursor were characterized by ...solid state 13C-NMR.•Thermal study of alkali-cellulose was proved to be higher than a parent cellulose.
Mercerized cellulose (alkali cellulose C6H10O5* NaOH) was obtained by treatment of cotton linters (cellulose) with aqueous sodium hydroxide. Cellulose and alkali-cellulose samples with relative density of 78% and 79% were obtained after sintering the material in air at optimal sintering temperatures of 423 K and 473 K, respectively. The electrical properties of the samples were studied by impedance spectroscopy in the frequency range from 13 MHz to 50 Hz at temperatures between 393 K and 493 K. The influence of cellulose mercerization on electrical properties of cotton linters was observed. The cellulose behaves like an electrical insulator. Contrariwise, the alkali-cellulose is a fast-ionic conductor with a conductivity value of σ473 K = 3.22 × 10−6 S cm−1 having activation energies of 0.49 eV and 0.68 eV at temperature range of 393 K–458 K and 459 K–500 K, respectively. The change of activation energy value has been discussed in relation to thermal stability.
• Polymorphic transformation of agave fibre during alkali processing was studied. • Both tenacity and crystallinity index increased until 2% NaOH and then decreased. • Variation in unit cell ...parameters is due to the formation of different alkali celluloses.
This study investigates the cellulose polymorphic transformation of Agave americana L. fibre during alkali processing at different NaOH concentrations. X-ray diffraction was used. The polymorphic transition from cellulose I to cellulose II begun at NaOH concentrations at the order of 5–10% and the complete transformation was achieved for the alkali concentration of 15%.
The crystallinity index of agave fibre increased for alkali treatments not exceeding 2% (w/v), whereas higher NaOH concentrations (>2%) induce a considerable decrease of the crystallinity index. The unit cell parameters of A. americana L. fibre vary with the NaOH concentration which results from the formation of different alkali celluloses during the mercerisation process.
As far as mechanical properties are concerned, treatments with low alkali concentrations produce fibres that are stronger than the untreated fibres, whereas treatments with high concentrations (>2% w/v) result in weaker fibres.
Herein, we demonstrate the activation of commercial chemical cellulose pulps towards chemical modification by a pre-treatment step with tetrabutylphosphonium acetate (P
4444
OAc). A heterogeneous ...(non-dissolving) pre-treatment was applied allowing for a significant reduction in crystallinity, without concomitant formation of the thermodynamically stable cellulose II. An increase in chemical reactivity was demonstrated using two model reactions; (1) acetylation (organic swelling conditions), where high degrees of substitution (DS) were obtained without the need for a catalyst, and (2) 4-acetamido-TEMPO oxidation (aqueous swelling conditions), where significant degrees of oxidation (DO) were obtained, beyond those for the untreated pulps. In both tests a notable improvement in cellulose reactivity was observed. Regioselectivity of acetylation was assessed using 2D NMR for one low and one high DS sample. The low DS showed a small degree of acetylation of the 6-OH, whereas, the high DS from the pre-treated sample showed mainly mixtures of triacetate and diacetates. Important mechanistic information is attained for future development of aqueous and organic-based reactions involving this ionic liquid pre-treatment.
The empirical force fields (FFs) based on molecular dynamics (MD) simulation studying the dissolution mechanism of cellulose in cold alkali solution suffers the lacking of reliable classical FFs for ...hydroxide. By a simple adjustment, we transferred one available polarizable force field (FF) of hydroxide into a nonpolarizable one and combined it with GORMOS FF. Simulation based on these parameters provided accurate hydration spheres and solution structure of hydroxide that is comparable to the polarizable one, providing an opportunity for the large‐scale MD simulation of the long cellulose chain in alkali/urea system for the study of dissolution and regeneration as well as mercerization process.
The global trend of environmental protection has led to replacing synthetic fibers in every feasible application with natural fibers. An alteration of the fiber's surface is essential for the natural ...fiber to be more suitable for use. In this study, the mercerization processes including 5% (wt/vol) sodium hydroxide solution at five different soaking times (15, 30, 45, 60, and 75 min), were used in this study to enhance various features of Ziziphus nummularia fibers isolated from Ziziphus nummularia plant stems. Results showed that 60 min alkalized Ziziphus nummularia fibers had cellulose content of 65.72%, which seems to be higher, and it was termed as optimally alkalized Ziziphus nummularia fibers. The thermal studies showed that optimally alkalized Ziziphus nummularia fibers had a degradation temperature of 360°C. The optimally alkalized Ziziphus nummularia fibers showed a crystalline index of 50.6% and crystal size of 3.52 nm. Epoxy composites were manufactured with various loading percentages of optimally alkalized and raw Ziziphus nummularia fibers to prove the application suitability. It was shown that 20 wt% of optimally alkalized Ziziphus nummularia fibers‐based epoxy composites showed a higher ultimate tensile strength of 40.31 MPa than all other composites. Scanning Electron microscope studies elucidated the fiber's surface behavior and other characteristics of fibers and tested epoxy composites.
ABSTRACT Background: Patauá (Oenocarpus bataua Mart.) is a palm tree belonging to the botanical family Arecaceae that occurs throughout the Amazon. Like açaí, an edible pulp is extracted from its ...fruits, remaining a fiber-rich waste. Revealing the potential of such raw or thermochemically modified fibers for producing bioproducts is a novelty in the literature. Therefore, this work aimed to characterize patauá fibers in natural and alkali-treated conditions to support future bioproduct applications. Alkaline treatments were performed under mechanical stirring combining two NaOH levels (5 and 10%) and two temperatures (80 and 100°C). Morphological characterization was performed by light microscopy and scanning electron microscopy (SEM). The contents of the structural and non-structural chemical components were determined, and chemical groups were evaluated by Fourier-transform infrared spectroscopy (FTIR). The physical characterization included moisture content, apparent density, and water absorption tests. Results: The macerate revealed short fibers with typical elongated morphology, mean cell wall thickness (4.10 µm) greater than the mean lumen width (3.01 µm), and mean length of 445 µm. The alkaline treatments partially individualized the fibers from bundles, cleaned extractives from the surface, and unblocked superficial pits by removing silica-rich structures. They substantially removed non-cellulosic components, but FTIR showed condensed lignin exposed on the fiber surface. Density and water uptake increased concerning natural fibers. Patauá’s short length and susceptibility to modification through thermochemical treatments that concentrated cellulose up to 50% indicated great potential for developing composites and nanofibers. Regardless of the NaOH content, 100°C was more efficient in concentrating cellulose. Conclusion: Patauá fibers have unique natural characteristics. They occur as flatted fiber bundles, have silicon-rich structures obstructing their superficial pits, and comprise more lignin than cellulose.
The need for eco-friendly materials made researchers move towards lignocellulose fibres as potential fortification materials for polymer matrices. In this regard, a unique fibre known as the coconut ...inflorescence fiber was extricated from the coconut tree and added to unsaturated polyester resin. As the fibres are subjected to mercerization treatment, XRD and FTIR studies show that the amorphous materials present in the fibers are removed, and the tensile strength of the fibre increases. For the tribology studies of the CIF/polyester composite, the load and sliding distance were chosen as the operation parameters under dry-sliding condition. Extensive testing demonstrated that the wear rate increases as the load increases, and it is reduced as the fiber volume faction increases. Due to the hardness of the composite materials, the wear rate decreases as the sliding distance rises. The composites with fiber volume fraction 25 % exhibit the minimum wear rate of the entire experimentation. Furthermore, the friction coefficient drops as the load and sliding distance increase with the increasing volume fraction, which is due to micro-melting generated by the frictional heat at greater loads. A SEM analysis revealed fiber pull-outs in composites with fiber volume fraction 30 %, owing to a lack of fibril wetting during the manufacturing of composites.
Most plant fibers are good sorbents of oil; however, synthetic sorbents have a much higher sorption capacity (SC) than plant fibers. This study evaluated the effect of fiber treatments, specifically ...hot-water treatment and mercerization, on the absorption characteristics of selected plant fibers. Five common plant fibers—corn residues, soybean residues, cotton burr and stem (CBS), cattail, and oak—were evaluated for their absorption characteristics in crude oil, motor oil, deionized (DO) water, and a 80:20 mix of DO water. The fiber treatments included ground fiber (control), hot-water treatment at 80 °C for 4 h and 125 °C for 4 h, mercerization at room temp for 48 h, and mercerization at 300 °C for 1 h. The absorption capacity (AC) varied with fiber type, absorption medium, and fiber treatment. Mercerization at 300 °C increased the water absorption of soybean residue up to 8 g/g. Mercerization at room temperature and the hot-water treatment at 125 °C increased the crude oil absorption capacity. After certain treatments, the crude oil absorption capacity of CBS and corn fibers increased over 5 g/g, and the motor oil absorption capacity of cattail, corn, and soybean also increased to 4 to 5 g/g.
This work describes the preparation of new chelating material from mercerized cellulose. The first part treats the chemical modification of non-mercerized cellulose (cell 1) and mercerized cellulose ...(cell 2) with succinic anhydride. Mass percent gains (mpg) and degree of succinylation (DS) of cell 3 (from cell 1) and cell 4 (from cell 2) were calculated. Cell 4 in relation to cell 3 exhibited an increase in mpg and in the concentration of carboxylic functions of 68.9% and 2.8
mmol/g, respectively. Cells 5 and 6 were obtained by treatment of cells 3 and 4 with bicarbonate solution to release the carboxylate functions and characterized by FTIR. The second part compares the adsorption capacity of cells 5 and 6 for Cu
2+, Cd
2+, and Pb
2+ ions in an aqueous single metal solution. Adsorption isotherms were developed using Langmuir model. Cell 6 in relation to cell 5 exhibited an increase in
Q
max for Cu
2+ (30.4
mg/g), Cd
2+ (86.0
mg/g) and Pb
2+ (205.9
mg/g).
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