Because the fiber is of chemical inertion, low surface energy, lack of polar groups, and highly symmetric methylene structure, the fiber has a high degree of crystallinity and orientation.

It is found that plasma treatment can impart the acrylic fiber increased surface roughness and the improved hygroscopicity by the introduction of polar functions containing oxygen and nitrogen.

The surface of the treated fibre contains more hydrophilic groups of oxygen and nitrogen. The increase of the number of polar surface groups accounts for the increase of fiber cohesion.