*3.1.4 Chemical recycling of blends*

The shortcoming of the depolymerization of waste from blended fibers depend on the differences in the fiber regeneration processes. There are ongoing efforts for successfully chemical recycling of blended materials.

In the products from cotton and polyester, chemical recycling has proven to be successful as selective degradation method is used by which the fibers can be artificially isolated and transformed into new ones. When a process using n-methylmorpholine-N-Oxide is applied, cellulose is dissolved. The dissolved cellulose and polyester are then separated by filtration and the captured polyester is respun into a fiber, filament, or yarn while the broken down cellulose can be utilized for the formation of MMCF [44, 60].

Financially viability of chemical fiber-to-fiber recycling of polycotton blends depends on the price and availability of sufficient volumes of well- textile waste and the market value of the resulting cellulosic pulp and polyester pellets [35].

#### **Figure 5.**

*A simplified process diagram for chemical recycling of cotton (adapted from [61]).*

The Japanese Teijin process, for example, is able to handle mixes of 80 percent polyester and 20 percent cotton. However, the process is very sensitive, and only uses Teijin products as input [68].

Nylon and spandex are also two fibers that are commonly used together especially in sportswear and usually, the percentage of nylon is considerably higher than that of spandex. Spandex can be expelled from the blend by dissolving it in solvents, for example, N,N-dimethyl formamide. However, this is a costly process with adverse environmental issues. There has been another successful approach for removing spandex by first treating the blend with heat to degrade the spandex and then washing by ethanol. At the end of the process spandex is successfully evacuated leaving just the nylon [44, 60].
