dryspinning

Dry spinning is a fiber production method in which a polymer solution, or dope, is extruded through spinnerets to form filaments in a stream of warm, dry air. The volatile solvent evaporates as the extrudate passes through a drying chamber, and the resulting solid fibers are drawn and wound. The process is continuous and typically takes place in a controlled environment to manage solvent evaporation and fiber orientation.

The equipment stack includes a dope preparation system, spinnerets, a drying or spinning chamber, and take-up equipment. Solvent vapors are often recovered and recycled to minimize emissions and solvent costs. The polymer concentration in the dope, the air temperature and flow, and the filament take-up speed govern the rate of solvent loss and the mechanical properties of the resulting fiber. Additional drawing steps may be used to increase strength and alignment.

Materials commonly produced by dry spinning include cellulose acetate and polyacrylonitrile-based fibers, as well as other polymers that dissolve in volatile solvents. Dry spinning is contrasted with wet spinning, where fibers are formed in a coagulating bath rather than by solvent evaporation in air. Dry spinning is advantageous for polymers that dissolve in easily evaporated solvents and allows high production rates, but it requires effective solvent recovery and careful handling of flammable or toxic vapors, along with energy-intensive drying. It is used primarily for textile fibers and certain specialty applications.