Fibrillation tendency of cellulosic fibers. Part 1: Effects of swelling

The fibrillation tendencies of various cellulosic fibers in aqueous solution containing alkali metal hydroxide and ethanol were evaluated with two specific parameters: the critical point of fibrillation (CPFconc.), that is a concentration of swelling agent where the fibrillation begins, and the ratio of initial increase in fibril number to increase in concentration of swelling agent (I-i). The CPFconc. and the I-i are defined as fibrillation stability and fibrillation sensitivity to swelling agent, respectively. Lyocell fiber (CLY1) has the smallest CPFconc. and the largest I-i, representing the lowest fibrillation stability and the highest fibrillation sensitivity, leading to the highest. brillation tendency in CLY1 among the fibers tested. Although crosslinking improved. brillation stability in lyocell as compared to modal, the. brillation stability remained higher owing to the high water capacity and the high affinity for alkali. In alkali solution at the same concentration CLY1. brillation increased in the order of LiOH > NaOH > KOH. However, the plot of fibril number against solvent retention value of CLY1 in different alkaline solutions gives a slope of 110 count (.) g/cm(3) regardless of alkali type, the critical degree of swelling for CLY1 with no. brillation was 0.62 cm(3)/g in alkali solutions and 0.45 cm(3)/g in ethanol/water