Invasive alien plant species represent an ecological challenge, while also offering an opportunity for sustainable and circular use of biomass. In this master’s thesis, Japanese knotweed (Fallopia japonica) was investigated as a source of natural colourants and bioactive components for the functionalisation of raw hemp fabric. The main objective was to evaluate the effect of low-pressure plasma pre-treatment on the dyeability of hemp fabric with an aqueous extract of Japanese knotweed rhizome and to assess the impact on functional properties. Hemp fabric samples were pre-treated with oxygen plasma, ammonia plasma at two treatment times, and a combined procedure in which hydrogen plasma was applied prior to ammonia plasma, after which dyeing with the extract was carried out. The effect of pre-treatment was evaluated using CIELAB colour coordinates and colour depth (K/S), and additionally by the ultraviolet protection factor, antioxidant activity, and wash and light fastness. The results indicate that ammonia plasma, particularly at the longer treatment time and in combination with hydrogen plasma, generally led to more pronounced changes in colour coordinates and greater colour depth, whereas under the selected conditions oxygen plasma was less effective. Ultraviolet protection increased after dyeing for all samples; however, only the sample treated solely with ammonia plasma for 180 s and then dyed reached the category of good ultraviolet protection. The highest antioxidant activity was observed for the sample treated with ammonia plasma for 180 s and then dyed. After washing, partial dye loss and lightening occurred in all samples, but the sample treated with the combined hydrogen and ammonia plasma procedure (3 times 5 s hydrogen and 180 s ammonia) retained the highest absolute colour depth after washing. Overall, the results confirm the potential of combining plasma pre-treatment and dyeing with an extract from an invasive plant for a more environmentally friendly functionalisation of hemp.
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