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Hydrogen peroxide represents an ecologically and economically acceptable agent for bleaching of flax fibers. The influence of hydrogen peroxide treatment under different conditions, i.e. hydrogen peroxide concentrations (1%, 2% and 4% w/v) and treatment temperature (50 degrees C, 80 degrees C and boiling temperature), on the chemical composition, electrokinetic and sorption properties and whiteness index of flax fibers, has been studied. The surface properties and water uptake behavior, i.e. swelling of untreated and treated flax fibers, were monitored through zeta potential measurements using the streaming potential method.The present research has found out that hydrogen peroxide simultaneously removes hemicelluloses and lignin from flax fibers. The ratio between the removal of hemicelluloses (hydrophilic component) and lignin (hydrophobic component), as well as changes in crystallinity, pore structure and carbonyl and carboxyl groups content, have a dominant effect on the electrokinetic, i.e. zeta potential versus pH and isoelectric point and sorption properties of the treated flax fiber. An increase of approximately three-to-four-fold in the whiteness index of the treated flax fibers has been observed. The established correlations between the modification conditions and properties of flax fibers, allow the utilization of hydrogen peroxide for bleaching and simultaneous fiber modification with the possibility of tailoringflax fibers properties. Graphic abstract

Cotton yarn was oxidized using the various concentrations and pH of potassium permanganate solutions, in order to investigate the influence of oxidation parameters on chemical, mechanical and sorption properties of cotton. The oxidation progress was monitored through weight loss, carbonyl and carboxyl group content, tensile strength, moisture sorption, crystallinity change, surface charge and morphology of modified samples. The carboxyl groups were introduced into the oxidized cotton up to 0.3 mmol center dot g(-1), while the weight loss was up to 5%. The oxidized samples, compared with untreated cotton, exhibited lower tensile strength, higher moisture sorption and surface roughness. Surface charge was evaluated through measurement of zeta potential at different pH of electrolyte, and the correlation was established between carboxyl group content and zeta values measured at neutral pH, which proved that zeta potential can be a valuable tool for characterizing changes in the structure of oxidized cellulose textile materials.

Applications of hemp fibers, as a promising natural material in the textile field, mostly require improved fiber properties. In this paper, the oxidation of hemp fibers with potassium permanganate was applied to reduce the amount of noncellulosic substances and moisture sorption; to introduce functional groups and increase capillarity; make fibers finer, softer and suitable for application in sport wears. The changes in sorption properties were characterized by capillary rise measurement and the ability of water retention and moisture sorption, while changes in mechanical properties were estimated by determination of tenacity and elongation of modified hemp fibers in comparison to the appropriate characteristic of unmodified fibers. ATR-FTIR, SEM techniques, and zeta potential measurement were used for the characterization of fiber structure, morphological and electrokinetic properties. We obtained a finer fiber with increased capillarity (up to 3.68 times) but reduced moisture sorption (down to 1.5 times) and water retention capacity (down to 2.8 times), with accomplished satisfactory preservation of mechanical properties. Obtained oxidized hemp fibers with attained features present a very suitable material for sportswear production. Additionally, in this paper, an improvement of the capillary rise measurement is given. Supplementary information: [https://cer.ihtm.bg.ac.rs/handle/123456789/4529]

This research proposed two pretreatments of viscose fabrics: oxidation with 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) and coating with TEMPO-oxidized cellulose nanofibrils (TOCN), to introduce functional groups (COOH and CHO) suitable for irreversible binding of chitosan nanoparticles without and with embedded zinc (NCS and NCS + Zn, respectively) and consequently achieving washing durable antibacterial properties of the chitosan nanoparticles functionalized fabrics. The characterizations of pretreated and chitosan nanoparticles functionalized fabrics were performed by FTIR and XPS spectroscopy, elemental analysis, inductively coupled plasma optical emission spectrometry, zeta potential measurements, scanning electron microscopy, determination of COOH and CHO groups content, and antimicrobial activity under dynamic contact conditions. Influence of pretreatments on NCS and NCS + Zn adsorption, chemical, electrokinetic, and antibacterial properties as well as morphology, and washing durability of NCS and NCS + Zn functionalized fabrics were studied and compared. Washing durability was evaluated through changes in the chitosan and zinc content, zeta potential, and antibacterial activity after 1, 3, and 5 washing cycles. Pretreatments improved washing durability of antibacterial properties of chitosan nanoparticles functionalized fabrics. The NCS and NCS + Zn functionalized pretreated fabrics preserved antibacterial activity against S. aureus after five washing cycles, while antibacterial activity against E. coli was preserved only after one washing cycle in the case NCS + Zn functionalized pretreated viscose fabrics. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4596]

In this paper, the principles of the action of the selective (NaIO4 and 2,2,6,6-tetramethylpiperidine-1-oxyl-TEMPO radical) and non-selective (H2O2 and KMnO4) oxidation agents on cellulose are presented. Their importance in modifying the existing properties or giving new properties to cellulosic materials, as well as examples of their applications are also given. The oxidation product - oxycellulose presents the base for obtaining a wide range of materials for special applications. Particularly, the influence of TEMPO-mediated oxidation on natural and man-made cellulosic fibers is presented, with a detailed overview on the type and quantity of introduced functional groups, changes in structure, sorption and mechanical properties. Also, we described the use of TEMPOmediated oxidation for the production of cellulosic nano-materials in the form of dispersions, particles and films, as well as the potential application of these nano-structural materials.

In situ synthesis of Cu/Cu2O nanoparticles on the cotton fabric discussed in this study relies on adsorption of Cu2+-ions by carboxylate groups generated through the TEMPO-mediated oxidation of cellulose and their subsequent reduction by sodium borohydride. In order to establish the influence of aldehyde and carboxylate groups on the nanoparticles formation, the duration of TEMPO-mediated oxidation was varied. Chemical changes induced by TEMPO-mediated oxidation were evaluated by titrimetric determination of the amounts of aldehyde and carboxylic groups in cotton and FTIR spectroscopy. The presence of Cu/Cu2O nanoparticles on the cotton fabric was confirmed by FE-SEM, AAS and XRD analyses. Antimicrobial activity of synthesized nanoparticles was tested against Gram-negative bacteria E. coli, Gram-positive bacteria S. aureus and fungi C. albicans. The extension of TEMPO oxidation time led to an increase of carboxylate group content and consequently, formation of larger amounts of Cu/Cu2O nanoparticles. All fabricated textile nanocomposites provided excellent antibacterial and acceptable antifungal activity. They also ensured a controlled release of Cu2+-ions in physiological solution which is an imperative for infection prevention.

The main objective of this study was to obtain chitosan functionalized viscose fabric with improved antibacterial properties and washing durability. In this regard carboxyl and aldehyde groups, as binding points for irreversible chitosan attachment into/onto viscose fabric, were introduced by two different pretreatments: 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) oxidation and coating with TEMPO oxidized cellulose nanofibrils (TOCN). The Fourier transform infrared spectroscopy, elemental analysis, zeta potential measurements, scanning electron microscopy, breaking strength and antibacterial testing were used to evaluate the influence of these pretreatments on chitosan binding, but also on chemical, electrokinetic, morphological, mechanical and antibacterial properties of pretreated and chitosan functionalized viscose fabrics. Washing durability of chitosan functionalized viscose was monitored through changes in the chitosan content, electrokinetic and antibacterial properties after multiple washing. TOCN coating improves mechanical properties of fabric, while TEMPO oxidation deteriorates them. The results show that both pretreatments improve chitosan adsorption and thus antibacterial properties, which are highly durable to washing. After five washings, the chitosan functionalized pretreated viscose fabrics preserve their antibacterial activity against Staphylococcus aureus, while antibacterial activity against Escherichia coli was lost. TOCN coated and chitosan functionalized viscose fabric is a high value-added product with simultaneously improved antibacterial and mechanical properties, which may find application as medical textiles.

The impact of nonselective cellulose oxidation (cotton fibre) by potassium permanganate in acidic environment, with or without additional treatment by sodium metabisulfite, on change of sorption (silver ions sorption), and deposition of manganese (IV) oxide were aims of this work. The standard methods and methods developed at Department of Textile Engineering of Faculty of Technology and Metallurgy Belgrade, were used for determination of introduced functional groups, sorption and mechanical properties of selected fibres. Inductively coupled plasma optical emission spectrometry ICP-OES was used for determination of manganese(IV) oxide deposited on cotton fibres. The changes of studied properties of cotton fibres were followed as a function of concentration and pH of the solution of oxidizing agent. Results obtained in this work showed that oxidized cotton fibre with improved sorption properties is appropriate as an initial raw for a wide range of textile products of special assignment. Cilj ovog rada je proučavanje uticaja neselektivne oksidacije celuloze (pamučna pređa) kalijumpermanganatom u kiseloj sredini, na promenu sorpcionih svojstava (joni srebra) i sadržaj deponovanog mangan(IV)-oksida. Tokom eksperimenta korišćene su standardne metode i metode razvijene na Katedri za tekstilno inženjerstvo Tehnološko-metalurškog fakulteta u Beogradu. Za određivanje sadržaja mangan(IV) oksida deponovanog na pamučnoj pređi je korišćena optička emisiona spektrometrija sa induktivno spregnutom plazmom (ICP-OES). Promene ispitivanih svojstava pamučnih pređa su ispraćene u funkciji koncentracije i pH rastvora oksidacionog sredstva. Rezulati dobijeni u ovom radu su pokazali da je oksidovana pamučna pređa pogodna polazna sirovina za dobijanje širokog spektra tekstilnih proizvoda specijalne namene. PR Projekat Ministarstva nauke Republike Srbije, br. OI 172029.