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  • Author: Jakub Wiener x
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Abstract

The aim of this study was to determine release rate and changes in polyphenols’ content, which were sorbed to carboxymethyl cellulose gel and subsequently desorbed. An aqueous extract of blue marc vine variety Fratava was used as a source of polyphenols. The gel was dried into a solid film and polyphenols were then desorbed again by dissolving this film in saline (isotonic) solution. Further, the influence of different times of high temperature (180°C) of drying gel on change in the amount of released polyphenols and also kinetics of their release in re-transfer of the film on the gel and solution was studied. The process simulates the possible use of carboxymethyl cellulose/ polyphenols film sorbed on textile materials and its contact with the tissues and body fluids such as course of wound healing.

Abstract

This study deals with the change of selected properties of samples of modified carboxymethyl cellulose after freeze drying. The investigated properties were changes in thickness, permeability, water sorption, thermal area resistance and thermal absorbing capacity. The prepared materials were evaluated by scanning electron microscopy. The product of presented technology has large internal surface, high wettability and biodegradability. It is nontoxic with high potential in biological applications.

Abstract

The ability of polyamide 6 nanofibers membrane (P6NM) to remove acid dyes from effluent solution by adsorption has been studied. Equilibrium isotherms for the adsorption of three acid dyes, Acid blue 41 (AB41), Acid blue 78 (AB78), and Acid yellow 42 (AY42), on P6NM were measured experimentally. Simulated wastewater of acid dyes with the concentration of 10 mg/L for sorption process electrospun polyamide 6 with mass per unit area 12 g/m2 was used as the sorbent material. Ten sets of P6NM were dipped in separate simulated effluent. The weight of the original P6NM and the concentration of left solution were detected. Results were analyzed by the Langmuir equation using a linearized correlation coefficient. And it showed that all the dyes tested could follow the Langmuir adsorption isotherm, which gave excellent correlation for all the dyes.

Abstract

The air flow and conjugate heat transfer through the fabric was investigated numerically. The objective of this paper is to study the thermal insulation of fabrics under heat convection or the heat loss of human body under different conditions (fabric structure and contact conditions between the human skin and the fabric). The numerical simulations were performed in laminar flow regime at constant skin temperature (310 K) and constant air flow temperature (273 K) at a speed of 5 m/s. Some important parameters such as heat flux through the fabrics, heat transfer coefficient, and Nusselt number were evaluated. The results showed that the heat loss from human body (the heat transfer coefficient) was smallest or the thermal insulation of fabric was highest when the fabric had no pores and no contact with the human skin, the heat loss from human body (the heat transfer coefficient) was highest when the fabric had pores and the air flow penetrated through the fabric.

Abstract

The limitation of aramid fiber is its surface property, which results in its very poor interfacial adhesion to most of commercial resins. In order to improve the surface property of the aramid fiber, ozone treatment was carried out in this work. The aramid fabrics were evaluated in terms of surface morphology, wicking effect, tensile property, and ball bursting test. The results showed that the surface morphology of aramid fabrics did not undergo an obvious change; the wicking effect increased slightly with an increase in ozone treatment time; the tenacity and elongation of aramid fibers and fabrics did not significant change after ozone treatment, but the tenacity and elongation of aramid yarns showed significant improvement after ozone treatment, and increased with the increase of ozone treatment time; the ball bursting load and penetration displacement had a slight increase as well after ozone treatment. Therefore, ozone treatment could be one method to improve the surface property of the aramid fiber.

Abstract

Polyester is a popular class of material used in material engineering. With its 0.4% moisture regain, polyethylene terephthalate (PET) is classified as highly hydrophobic, which originates from its lack of polar groups on its backbone. This study used a parallel-plate nonthermal plasma dielectric barrier discharge system operating at medium pressure in dry air and nitrogen (N2) to alter the surface properties of PET fabrics to increase their hydrophilic capabilities. Water contact angle, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were utilized to analyze any effect from the plasma treatment. The wettability analysis revealed a reduction in the contact angle of more than 80% within 5 min for both discharges. Scanning electron microscopy analysis showed no microscopic damage to the fiber structure, guaranteeing that the fabrics’ structural integrity was preserved after treatment. AFM analysis showed an increase in the nanometer roughness, which was considered beneficial because it increased the total surface area, further increasing the hydrophilic capacity. XPS analysis revealed a sharp increase in the presence of polar functional groups, indicating that the induced surface changes are mostly chemical in nature. Comparing that of untreated fabrics to treated fabrics, a Increase in water absorption capacity was observed for air-treated and N2-treated fabrics, when these fabrics were used immediately after plasma exposure.

Abstract

This study deals with a comparison of mechanical properties of a conventional yarn and a textile from nanofibres. The conventional yarn represents the textile objects with high degree of orientation of fibres and the textile from nanofibres represents the textile objects with low degree of orientation of fibres. The theoretical section is concerned with the issue of internal structure of plied yarn and resulting differences in the orientation and straightening of fibres and in utilisation of deformation properties of fibres in comparison to the referred nano textile. The experimental section describes the manner of realisation of both static and dynamic tests of conventional yarn and strips of nanofibres. The results show differences in the mechanical properties of conventional yarn and textile strip from nanofibres under static and dynamic loading conditions. The processing technology of conventional yarn has been verified in the long term. But textiles from nanofibres are a relatively new material and mechanical properties of the detected differences point out possible problems with their behaviour during standard technological processes.