Why Acrylic Fiber Uses Wet Spinning Process

Acrylic fiber is primarily manufactured using the wet spinning process because the acrylic polymer exhibits poor thermal resistance. This means it degrades or decomposes at temperatures required for melt spinning.

Understanding Polymer Properties and Spinning Methods

• Melt Spinning: This method requires the polymer to be meltable at high temperatures without decomposing. Examples include polyester and nylon.
• Wet Spinning: This method is suitable for polymers that degrade at high temperatures. The polymer is dissolved in a suitable solvent, extruded as a solution, and then solidified by precipitation in a chemical bath.

Acrylic Polymer's Thermal Limitation

Acrylic polymers tend to decompose rather than melt cleanly when heated. Attempting melt spinning would lead to polymer degradation, resulting in fiber breakage and poor fiber quality. Therefore, the poor thermal resistance of the acrylic polymer makes melt spinning unsuitable.

Wet Spinning as the Preferred Method

The wet spinning process bypasses the need for high melting temperatures. By dissolving the acrylic polymer in a solvent (like dimethylformamide or acrylonitrile), it can be spun into fibers at much lower, non-damaging temperatures. The resulting solution is extruded through spinnerets into an aqueous or chemical bath, causing the polymer to precipitate and form solid fibers. This avoids thermal degradation.

Conclusion: The choice of wet spinning for acrylic fiber production is directly dictated by the polymer's inherent poor thermal resistance.