Regeneration of cellulose fibers from cotton roll towels by means of the Ioncell® process

Abstract

In this thesis a route for the recycling of pre-consumer, post-consumer and dyed waste cotton via the novel Ioncell® (Sixta et al., 2015) process is presented. Indicated by a broad molar mass distribution the cotton waste samples were heterogenous by nature and showed a high degree of polymerization. Acidic treatment was performed in order to adjust the degree of polymerization suitable for the Ioncell® spinning process. The starting materials were dissolved in 1,5-diazabicyclo (4.3.0) non-5-ene acetate [DBNH][OAc], converted to new colored and white cellulosic fibers by the dry-jet wet extrusion technology, washed and reconditioned. The mechanical and optical properties of the regenerated fibers were analyzed in detail via approved methods (SEM, birefringence, mechanical testing, XRD, FTIR, TG/DSC). All of the regenerated fibers exhibit a significantly higher tenacities of around 60 cN/dtex with an elongation of 10% compared to native cotton fibers and commercially available fibers (e.g. viscose and lyocell fibers). Besides, after spinning a loss in color and a slight reduction of the crystallinity were recognized in case of the fibers produced from dyed cotton. Whereas, no significant change in the chemical structure was noticed.