The persistent demand for sustainable and eco – friendly fibres able to achieve high performance materials drew the attention to bast fibres, which, in this regard, represent an attractive resource. They are characterised by their fineness, flexibility, and excellent tensile properties due to the cellulose volume fraction. In particular, the fibre of the Himalayan giant nettle plant (Girardinia diversifolia), which grows in Africa and Asia, simultaneously provides social and environmental benefits as well as attractive physical properties, making it an interesting fibre for high performance sustainable textiles. This research provides an unprecedented investigation on giant Himalayan nettle fibres, currently processed and used in the handicraft, performed in parallel with common European nettle fibre (Urtica dioica) already used in the textile industry. The morphological, physical, and mechanical characterisation of G. diversifolia fibres provide encouraging results, indicating a substantial superiority (in terms of physical and mechanical properties) of Himalayan nettle fibres compared to the most common textile bast fibres. Himalayan nettle fibres displayed higher tensile strength, tensile modulus, and elongation at break with respect to European nettle fibres. Furthermore, the Himalayan nettle fibre is the longest bast fibre known so far. Its moisture content results indicate effective dielectric insulating capacity. The values of moisture regain, inferior to cotton, show that the fibre physical characteristics are not affect by humidity. Treatment with increasing concentrations of sodium hydroxide (NaOH) was carried out in order to induce changes in the molecular structure, from Cellulose I to Cellulose II, of both Himalayan and European nettle fibres, and to assess how this variation could influence their physical and mechanical characteristics. This research has identified as best result the fibre versatility: the ability to obtain, with alkaline treatment, characteristics of the fibre able to meet different purposes. To make the fibre attractive for the textile industry, Himalayan nettle fibre has to be competitive demonstrating that it can work in technical textiles. The field of outdoor sportswear, where a high level of comfort is required, has been chosen to demonstrate the performance of the Himalayan nettle fibre hypothesising a multilayer fabric made of three Himalayan nettle nonwovens treated at three different concentrations of NaOH. Based on its superior fibre length and mechanical strength, Himalayan giant nettle fibre could be a very promising material for advanced nonwovens where high – performance materials are required.
