Influence of moisture on wettability and sizing properties of raw cotton yarns treated with He/O2 atmospheric pressure plasma jet

► Raw cotton fibers with different moisture regains were plasma treated. ► Cotton fibers with 0.5% moisture regain were more efficiently etched and imparted more polar bonds. ► Cotton fibers with 26.4% moisture regain got the worst hydrophilicity after treatment. ► The adhesion between the fiber and the size became weaker as the moisture regain rose up. ► The cotton roving with 0.5% MR had a relatively uniform layer of size permeation.