Natural dyes, obtained from plants, insects/animals, and minerals, are renewable and sustainable bioresource products with minimum environmental impact. However, there are still many issues to solve related to natural dyes; consequently, synthetic dyes are still wildly used. Natural dyes have a low affinity towards the substrate cotton, so a solution had to be found: mordants. Mordants can also be harmful to the environment, which is why bio-mordants are used. The mordant used in this paper is chitosan. Cotton is pre-mordanted using the pad dyeing method. By using the exhaustion method, the fabric was coloured with red Camellia sinensis (tea) extracts. The colour, absorption of polyphenols and tannins, and ultraviolet protection (UPF) were tested. A comparison study was carried out between the cotton fabric and the cotton padded with chitosan at two different concentrations. The results are impressive. Cotton pre-mordanted with chitosan can absorb more polyphenols and tannins than cotton itself, and the colour fastness and UPF, once the fabric is laundered, demonstrate there is some kind of bonding between the fibre, quitosan, and active compounds from tea. The UPF was also doubled by using chitosan and the reddish colour obtained by Camellia sinensis extracts were darker on the cotton fabric. The increase in UPF protection on mordanted fabrics is higher than the gap obtained by colour difference, which means there are active compounds that do not confer colour, but enhance UPF protection.

Electrospinning makes it possible to obtain solid fibers, in addition to core-shell fibers, using coextrusion. However, an exhaustive control of parameters allows the core-shell fibers from emulsion electrospinning to be obtained. The solvent in the outer surface tends to evaporate and the polymer density increases, moving the emulsion drops towards the center, which in turn promotes coalescence, thus creating the core. The aim of this work was to avoid coalescence and obtain a net of nanofibers entrapping oil microcapsules. We obtained an emulsion oil in water (O/W), with polyvinyl alcohol (W) and two essential oils (O), sage and thyme. An electrospinning process was used to place the microcapsules of oil inside a net of nanofibers. The electrospun veil was characterized by organoleptic testing, SEM microscopy, FTIR spectroscopy, DSC thermal analysis, and pressure tests. Organoleptic testing, FTIR spectroscopy, and DSC thermal analysis demonstrated the presence of the oil, which was retained in the spheres observed by SEM microscopy, while pressure tests revealed that the oil remained in a liquid state. Furthermore, we demonstrated a strong relationship between the emulsion size and the final microcapsules created, which are slightly larger due to the shell formation. The size of the emulsion determines whether the spheres will be independent or embedded in the nanofibers. Furthermore, the nanofiber diameter was considerably reduced compared to the nanofibers without the oil.

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Information about the paper titled "CIRCULAR ECONOMY OF FIBROUS COMPOSITES AND TECHNICAL TEXTILES E-LEARNING" at IATED Digital Library