Preparation, compatibility and structure of acetylated cellulose/lyocell composite fiber

The study investigated the structures and properties of lyocell composite fibers with acetylated cellulose with varying relative acetylation substitution degrees (RDS). During pretreatment with NaOH/ethanol solution, some acetyl groups in the acetylated cellulose were hydrolyzed, leading to improve solubility in N-methylmorpholine-N-oxide (NMMO). The RDS was utilized to quantify the content of acetyl groups and acetylated cellulose with RDS between 0.516 ~ 0.571 that could dissolve in NMMO completely. The compatibility between cellulose and acetylated cellulose, with RDS values of 0.516, 0.543 and 0.571 respectively, was demonstrated through rheological and contact angle tests. Although the addition of acetylated cellulose did not change the crystalline structure and comprehensive performance of the composite fiber, it mainly disturbed molecular orientation of amorphous region, crystallinity and grain size. Besides the strengthening of hydrogen bonding between the two components, and the transverse connection between the aggregates were enhanced, thus reducing fibrillation. This paper provides a green modification approach that can be scaled up for industrial application, aiming to mitigated fibrillation issues in lyocell fibers.