Fabric dyeing with colorimetric pH‐responsive colours. (24th November 2020) - Peila, Roberta
Abstract: This paper explores the possibility of dyeing textile fabrics with halochromic dyes. Five different halochromic dyes were tested: bromocresol purple, m‐cresol purple, chlorophenol red, curcumin and bromothymol blue. Preliminary dyeing was carried out on wool, polyacrylonitrile, polyester, polyamide 6.6, cotton and cellulose acetate at 100°C for 40 minutes to evaluate affinity. All the dyes showed good affinity to wool and polyamide 6.6. Cotton required a mordant phase before dyeing. Washing and light fastness were evaluated for the dyed fabrics, as well as colour changes at different pH values. Some fibres displayed good dye fastness and halochromic properties. Bromothymol blue was selected to dye polyamide 6.6 and cotton fabrics. The dyed fabrics displayed good halochromic properties across a pH range of 4 to 10. Cotton fabrics exhibited an immediate colour change; polyamide 6.6 changed colour after several minutes. An industrial dyeing process was performed on natural cellulosic fibres. The results confirmed the possibility of scaling up the process with regard to textile applications of halochromic dyes.