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Cellulose is a strong contender for the development of sustainably resourced biodegradable material composites supporting circular economy. Nanofibrillar cellulose-comprising materials are among the most promising lignocellulose derivatives. Currently, their production capacity and economy are hindered by high chemical and energy consumption, the latter primarily during mechanical fibrillation of native fiber in aqueous suspension and the negative limitation of very low solid content associated with the gel-like properties of the resulting final product. The application of oxygen gas barrier discharge (DBD) plasma on dry cellulose fiber, as reported here, is considered novel in achieving onward nanofibrillation. At this early stage, though, simple laboratory DBD equipment precludes the study of overall efficiency. Example fiber was taken from paper pulp manufacture but may not be limited to wood source. The oxygen plasma was seen to etch the microcellulose fiber structure, simultaneously oxidizing the glue-functioning hemicellulose, rendering it soluble, so that nanopolymer crystalline-based cellulose fibrils can be readily released at the surface of the host refined microfiber at the point of application, forming micro nanofibrillated cellulose structure (MNFC) at previously uneconomic higher solid content. Eliminating the need for liquid water during precursor process treatment is considered potentially transformative with respect to production feasibility, end-product transportation and application.

The electrokinetic properties of materials give useful insight into the behavior of surfaces in contact with liquids and other compounds and their quantification is a powerful tool to predict their behavior during further processing and application, especially in textile materials. In this work, we perform a comparative analysis of influence of the two most common selective oxidative protocols for viscose (regenerated cellulose) fabrics on subsequent functionalization with chitosan, and cellulose fabrics’ electrokinetic properties, zeta potential in a pH range of approx. 3–10, and isoelectric point (IEP). For oxidation before deposition of chitosan, sodium periodate and 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) were used. The content of functional groups in oxidized cellulose fabric (carboxyl and carbonyl groups) was determined by titration methods, while amino functional groups’ availability in samples with chitosan was determined using the CI acid orange 7 dye absorption method. This study reveals that the periodate oxidation (PO) of cellulose is more effective for binding chitosan onto material, which gave rise to higher availability of amino groups onto cellulose/chitosan material, which also influenced the shift in zeta potential curve towards positive values at a pH below 5. Analysis of a relationship between zeta potential increase at pH 4.4 and amino groups’ amount measured using absorption of CI acid orange 7 dye at pH 4.4 revealed dependency that can be fitted linearly or exponentially, with the latter providing the better fit (R2 = 0.75).

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·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.