Conversion of a conventional to a digital lecture under the conditions of Covid19 – an example from a bachelor lecture on finishing, dyeing & printing

Due to the Covid-19 pandemic situation during the years 2020 and 2021, the necessity occurred to convert conventional university lectures into digital ones, to avoid personal contacts between people and by this minimizing the spreading of the disease. Beside lectures, also exams have to be transferred to minimize personal contacts. This paper reports on a lecture in a bachelor course with more than 100 students and its conversion to digital format. The lecture is related to textile finishing processes – especially to dyeing and printing. The experience get during the digital lecture are compared with the results gained during the last decade with the same lecture in conventional style. Main tools of the digital format are video conferences and digital worksheets. Challenging are the contact to students by e-mail and the time management of the students especially during the final digital homework. In conclusion, digital lecture and exam are valuable tools to increase the number of participating students and their success in the exam. These tools could be also used successfully in post-corona times especially for lectures given for experienced students in higher semester.

Improvement of the electromagnetic properties of blended electromagnetic shielding fabric of cotton/stainless steel/polyester based on multi-layer MXenes

Blended electromagnetic shielding (EMS) fabrics of cotton/stainless steel/polyester have been widely applied. The porous structure of the fabric is the guarantee of its good comfort performance, but it also hinders the improvement of shielding efficiency and the endowing of wave absorption performance. To solve the above problems, this paper proposes a mixed resistance field based on fabric pores by the construction of multi-layer MXenes. Ti3AlC2 is etched by hydrochloric acid and lithium fluoride to generate hydrofluoric acid in situ to prepare multi-layer Ti3C2T x. The finishing experiments are designed to finish the fabric around the pores with Ti3C2T x impregnation. The enhancement effect and mechanism of the mixed resistance field on the shielding effectiveness and wave absorbing properties of the fabric are analyzed. The result shows that the multi-layer Ti3C2T x for textile finishing is prepared quickly and effectively using the proposed method. The micro media of the Ti3C2T x in the dispersion are adsorbed on the surface of various fibers, most of which are cotton fibers. The shielding effectiveness of the finished EMS fabric is improved significantly in the frequency ranges of 6.57–14 GHz and 11.97–18 GHz. The wave absorbing performances in the frequency range of 11.97–18 GHz are excellent. It is proved that the effect of the mixed resistance field of the pores was satisfactory. This paper provides a new way for the application of Ti3C2T x in EMS fabric, solves the disadvantages caused by pores, and can provide a reference for the design and production of wave absorbing EMS fabric.

Sustainable functional finishing for cotton fabrics using screen-printing process and gallotannin

To seek a more environmentally friendly textile finishing technique, the screen-printing method was adopted to apply functional material to cotton fabrics. In addition, gallotannin was used as a functional material because it is naturally abundant in many plant-derived substances and shows various health-promoting features such as antimicrobial, antioxidant, and other attractive properties. Therefore, a gallotannin/thickener paste was applied to the surface of cotton fabrics through the screen-printing technique, and the gallotannin-printed cotton fabrics were thoroughly investigated using scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and other methods. The gallotannin printed area was substantially brown in appearance, and gallotannin moiety appeared to combine with cotton cellulose through heat treatment. Furthermore, functional properties of the gallotannin-printed cotton fabrics were examined in terms of antibacterial activity, deodorizing property, and ultraviolet-blocking property, of which it demonstrated excellent abilities. However, the antibacterial ability toward Gram-negative bacteria (K. pneumoniae) decreased as the laundry cycle increased.

Enhanced Knittability of Paper Yarn from the Swedish Forest by Using Textile Finishing Materials

Friction between Swedish paper yarn and needles is a limiting factor that—together with the low yarn flexibility—is hindering the knitting and use of paper yarn as a sustainable textile material. To enhance the knittability, paper yarn was coated with textile finishing materials. The effect of six different textile finishing materials used for textiles processing (three different silicone-based, wax, glycerol, and soap) was evaluated. The treatment evaluation was done by determination of the friction coefficient, tensile testing, and knitting. The friction coefficient was determined by an adaption from the ASTM D3108-07 Standard Test Method for Coefficient of Friction, Yarn to Solid Material. The adaption meant using a specially designed rig, making it possible to simulate the yarn/needle friction during the knitting process and use a tensile testing machine to determine the friction coefficient. Through using the same angle for yarn movement during the knitting process in this adaptation, the effect of the flexibility of paper on the friction coefficient is integrated. Tensile testing was performed using a Tensolab 2512A/2512C electromechanical tensile tester, and knitting tests were performed using a Stoll CMS 822 HP knit and wear flat knitting machine with the E5.2 gauge. The results show that knittability is better for the yarns with lower coefficients of friction and can also be enhanced by spraying with regular water. The tensile properties of the yarn is degraded by the treatments. The wax- and soap-treated yarns were most challenging to knit. The silicone-based and glycerol-treated yarns showed enhanced knittability, where the glycerol treatment results in more protruding fibers compared to the other treatments. All treatments reduced the roughness in the feel of the knit. The results indicate that the Swedish paper yarn can be a future sustainable complement to polyester and cotton.

CELLULOSE NANOMATERIALS IN TEXTILE APPLICATIONS

Nanocellulose (NCC) has attracted increasing attention for use in several applications owing to its impressive strength-to-weight ratio, ease of functionalization, and apparent biocompatibility. In the nanocomposite textile field, NCC has exhibited outstanding potential for reinforced fibers, especially fibers processed by solution spinning. Continuous NCC fibers with high modulus and strength can be obtained, while preserving the cellulose I crystal structure. Owing to the various possibilities of surface modification, NCC is an efficient adsorbent of cationic and anionic textile dyes, as it reaches maximum removal capacities comparable to those of commercial adsorbents. In dyeing, NCC contributes in improving dye fixation and reducing the consumption of chemicals and water. In this review, recent studies on the applications of NCC in the textile field are discussed. The main methods, advances and limitations, regarding the NCC applications for fiber reinforcement of water-soluble and insoluble materials, dye removal and textile finishing, are presented.

Sustainable Functional Finishing For Cotton Fabrics Using Chestnut Shell Extract

Owing to global environmental concerns, sustainable industrial processes have become a topic of significant importance in various fields. Chestnut shells are byproducts of agricultural and food industries; however, they include various health-beneficial compounds such as polyphenols and flavonoids. In this study, the feasibility of using chestnut shell extract as a natural functional agent for textile finishing processes was investigated. The chestnut shell extract was prepared by boiling the inner and outer shells of chestnut in distilled water for 4 h. Subsequently, the extract was filtered, centrifuged, concentrated, and finally dried into powder form using a freeze dryer. The extract was then dissolved in distilled water at different concentrations and applied to cotton fabrics through a pad-dry-cure process. The finished cotton fabrics were investigated by scanning electron microscope, Fourier-transform infrared spectroscopy, etc. In addition, the antibacterial and antioxidant properties of the finished cotton fabrics were examined as functional properties. The results showed that the cotton fabrics finished by chestnut shell extract exhibited significant antibacterial, antioxidant, and deodorant properties when the concentration of the chestnut shell extract was above 10 wt% in the finishing bath.