Relationships Between Fibrillation Behavior of Lyocell Fibers and Their Physical Properties

Lyocell, a novel cellulosic fiber, has superior mechanical properties along with envi ronmental friendly aspects. Nevertheless, in some applications, its fibrillation behavior is considered to be a drawback. This behavior can be easily measured by the so-called fibrillation index, which is a value indicating the degree of fibrillation of the fibers. This paper investigates the relationship between the degree of fibrillation of Lyocell fibers and three of their physical properties: birefringence, viscosity. and relative crystallinity. Optical microscopy is used to determine the fibrillation indices of Lyocell fibers after being finished with a commercial crosslinking agent in various concentrations. Birefrin gence, viscosity, and relative crystallinity are studied with polarized optical microscopy. the dilute solution technique, and x-ray diffractometry, respectively. The results show that certain concentrations of the crosslinking agent can be used effectively to control the degree of fibrillation. Relative crystallinity and birefringence decrease steadily, while the concentration of crosslinking agent increases. Intrinsic viscosity marked increases when concentrations of crosslinking agent are higher. There are firm relationships between the fibrillation index and these three properties; accordingly, a simple mathematical model is derived to predict the degree of fibrillation in relation to them.