The influence of conditioning baths on the structure and properties of fibers spun from cellulose with low alpha content

For many years, the production of artificial cellulose fibers has been associated with the viscose process, which is inherently environmentally hazardous and unacceptable in modern conditions. The NMMO process is an alternative in which cellulose solutions are obtained using a direct solvent, N-methylmorpholine-N-oxide (NMMO). Spinning solutions in NMMO can be made from cellulose with a high concentration of impurities (lignin, hemicellulose, etc.). Metals that affect solvent and polymer stability are an exception; their content should not exceed the acceptable levels. Conditioning fibers in baths of diverse compositions is one of the most important stages of structure formation. Keeping fibers made from paper-grade pulp in conditioning baths causes changes in not only the size of crystallites and the degree of crystallinity, but also in mechanical characteristics. Thus, after completely removing the solvent and immersing the fibers in alcohol, the crystallinity rises as compared to fibers that have just received water baths. Strength and elastic modulus attain their peak values, while relative elongation falls to 3–6 %. Regardless of the structural alteration, all corrugated fibers keep their crimp, color, and organoleptic qualities.