Chitosan application in textile processing and fabric coating

Textile manufacturers and related industries are undergoing a change due to legal regulations, as well as their commitment for social responsibility and the increased ecological awareness of customers. Turning from established fossil-based value chains towards more sustainable bio-based products is one of the key factors to achieve these goals. Together with a previous view on the general textile processing value chain, the most promising application fields of chitosan, are elucidated within this review. A summary of the commonly applied physical-mechanical or application specific test methods for textile fabrics is part of the chapter in order to assess chitosan performance. A brief overview about chitin fibre production introduces different methods to manufacture chitosan fibres, such as wet spinning and electrospinning. The physical-mechanical properties are discussed whereby chitosan fibres show low to medium tensile properties. Another application is the utilisation of chitosan as a sizing agent that efficiently protects yarns during weaving. Chitosan films exhibit a suitable value range of significant properties, such as viscosity, surface tension, adhesion power and mechanical properties. Removal of chitosan from the yarn or fabric as well as recycling after weaving is explained. Another part deals with the application of native or modified chitosan as a permanent coating or finishing agent on a textile fabric meant to be nonremovable. Due to the amine functionality of chitosan, the polysaccharide could be modified with versatile reagents to gain various desired properties. Furthermore, a cross-linking is desired in order to increase the washing fastness required for a marketable product. Besides antibacterial activity, which has already resulted in the development of commercial chitosan-containing formulations, further beneficial properties that have commercial viability are anticipated. The removal of dyes and heavy metals with chitosan-grafted fabrics, the increased dyeing ability of fabrics, and advantageous crease recovery properties are also presented.