In this paper, we present the construction of a reliable and inexpensive pH stat device, by using open-source “OpenPhControl” software, inexpensive hardware (a peristaltic and a syringe pump, Arduino, a step motor…), readily available laboratory devices: a pH meter, a computer, a webcam, and some 3D printed parts. We provide a methodology for the design, development and test results of each part of the device, as well as of the entire system. In addition to dosing reagents by means of a low-cost peristaltic pump, we also present carefully controlled dosing of reagents by an open-source syringe pump. The upgrading of the basic open-source syringe pump is given in terms of pump control and application of a larger syringe. In addition to the basic functions of pH stat, i.e. pH value measurement and maintenance, an improvement allowing the device to be used for potentiometric titration has been made as well. We have demonstrated the device’s utility when applied for cellulose fibers oxidation with 2,2,6,6-tetramethylpiperidine-1-oxyl radical, i.e. for TEMPO-mediated oxidation. In support of this, we present the results obtained for the oxidation kinetics, the consumption of added reagent and experimental repeatability. Considering that the open-source scientific tools are available to everyone, and that researchers can construct and adjust the device according to their needs, as well as, that the total cost of the open-source pH stat device, excluding the existing laboratory equipment (pH meter, computer and glossary) was less than 150 EUR, we believe that, at a small fraction of the cost of available commercial offers, our open-source pH stat can significantly improve experimental work where the use of pH stat is necessary.

In this paper, the influence of the catalytic oxidation using water soluble and stable nitroxyl radical 2,2?,6,6?-tetramethylpiperidine-1-oxyl (TEMPO) on structure and properties of cotton fibers was studied. In particular, the selective TEMPO-mediated oxidation has become very interesting way for introduction of functional groups into cellulose fibers with the aim to obtain oxycellulose fibers with specific properties. Unmodified and modified fibers were characterized in terms of weight loss values, introduced functional groups and crystallinity index. Also, oxidized fibers were characterized in terms of the sorption, morphological, and physico-mechanical properties. The TEMPO-oxidized cotton fibers show a minimum increase of fineness (from 1.32 to 1.28 dtex) and increase of crystallinity index (up to 91.9%), while the tensile strength of fibers decreases (up to 10.82 cN/tex). By the TEMPO-mediated oxidation of cotton fibers significant amount of carboxyl groups (up to 0.795 mmol/g cell) can be introduced into cellulose fibers. Introduced hydrophilic carboxyl groups increases the sorption properties of oxidized fibers, that can be used directly or for further chemical modification.

In this paper, the capillary rise and sorption ability of hemp fibers oxidized with hydrogen peroxide and potassium permanganate were studied, with the aim to get more insight into the changes in the structure of hemp fibers caused by oxidation, and to compare the influence of applied oxidative agents on hemp fibers. Capillary rise was presented as a function of a liquid rise height vs times, with determined all three capillary coefficients, while sorption ability was determined as water retention values and moisture sorption. For structural analysis of the samples the ATR-FTIR technique was used. Also, the amount of aldehyde and carboxyl groups and the lignin content in oxidized fibers were determined. The surface fibers morphology was observed by FESEM. In all oxidized hemp fibers an increase in capillarity was obtained for both oxidizing agents (33–75 mm for H₂O₂, and 40–114 mm for KMnO₄), compared to 31 mm for unmodified fibers, but decreased sorption ability. Application of both oxidative agents, were successful for introduction of functional groups into oxidized fibers, for reduction of the amount of non-cellulosic substances, as well as moisture sorption. Simultaneously, the fibers became finer, cleaner, whiter, softer and more suitable for further processing, while, generally, higher influence on changes into oxidized hemp fibers was achieved by oxidation with KMnO₄, compared to oxidation with H₂O₂.

Liquid transport in textile fabrics determines thermal comfort during high physical activity of a person when liquid perspiration is produced and needs to be transferred away from the skin to keep the thermal balance. In this investigation, an attempt was made to get some indications of how the combination of the fabric composition, geometry and dimensional stability, and the moisture content influences liquid transfer properties of plain weft knitted fabrics. Therefore, the knitted fabrics made from pure hydrophilic (hemp fibres), pure hydrophobic (acrylic fibres) and a hydrophilic/hydrophobic (hemp/acrylic) fibre blend underwent a trial wear and care period. The Malden Mills water distribution test was performed for the knitted fabrics with different moisture contents (0-30 %) in order to evaluate the effect on liquid transfer properties. Water transfer ability and water holding capacity of the knitted fabrics were also determined after undergoing the wear trial test. The obtained results were analysed with respect to macro and micro scales of porosity of knitted fabrics. It has been shown that the geometric configuration of the complex porous network in knitted fabrics influenced their liquid transfer properties in the whole moisture content range regardless of the composition. Despite the reconfiguration of the pore system in the knits during the trial period, their liquid transfer properties were still dependent on the pore size and distribution.