Cold pad-batch dyeing of cellulose nanofibers with reactive dyes

The dyeability of electrospun nanofibers for apparel application has recently gained substantial interest. Past work focused on batchwise and continuous dyeing methods, but they required a certain temperature for dye fixation. We report on the dyeing of cellulose nanofibers by the cold pad-batch method, which offers the most economical and convenient method of dyeing cellulosic nanofibers with reactive dyes. Cellulose acetate (CA) nanofibers were fabricated via electrospinning and then deacetylated to convert CA into cellulose nanofiber. The cellulose nanofiber webs were dyed with three different classes of reactive dyes. CI Reactive Black 5 obtained the highest color yield in comparison to CI Reactive Red 195 and CI Reactive Blue 19. The dye fixation for all dyes achieved between 80 and 85 %. Except color fastness to light, washing fastness of dyed cellulose nanofibers obtained very good to excellent results. To investigate the chemical structure and fiber morphology of the cellulose nanofibers, Fourier transform infrared spectroscopy and scanning electron microscopy were used respectively.