ABSTRACT
Wet-spinning acrylic fiber had its origins in the mid-1850s with the wet spinning of cellulosics by Cbardonnet. Raw cotton was nitrated with a sulfuric acid/nitric acid solution. The resultant cellulose nitrate was then dissolved in a 40/60 ethyl ether/ethyl alcohol solvent to make a viscous "dope." This dope was forced through a spinnerette to form fibers of cellulose nitrate. After washing and stretching to orient the polymer chains and thus improve strength, the fiber was denitrified in an ammonium hydrosulfide bath. Further treatments were required to remove impurities and bleach the product. This first commercial process for synthetic fiber which was practiced into the late 1940s is shown schematically in Figure I. The Chardonnet process exemplifies important principles used in synthetic fibers-the use of a soluble intermediate to effect the conversion to fiber, phase separation in the formation of a fibrous network, and aftertreatment to generate the desired fiber structure. Elements of these solution-spinning processes are still practiced today in the manufacture of rayon fibers.
