Bågenholm-Ruuth and his colleagues have developed a process, described in a recent issue of Cellulose, to loosen up and convert the complex cotton fibers into viscose fibers. The process uses hydrated zinc chloride (ZnCl2.4H2O) as a solvent and swelling agent to convert waste cotton textiles into a dissolving pulp. The pulp can then be used to make viscose dope, a spinning solution that can be spun into stable viscose fibers.
The process has the advantage of using ZnCl2.4H2O, a soluble, inexpensive salt, and requires a smaller percentage of carbon disulfide compared to standard viscose-spinning processes. The result is good-quality viscose fiber, even though the process needs to be further optimized, Bågenholm-Ruuth says. Also, an additional step may be required for recycling old clothing that has been dyed.
Startup company ShareTex AB (Bjärred, Sweden; ) is working to further develop the technology. The process could be demonstrated at commercial scale within five to seven years.