Effects of tetramethylammonium hydroxide (TMAH) treatment on interfibrillar structure of lyocell (TENCEL) fibres

Lyocell fibres were treated with tetramethylammonium hydroxide (TMAH) up to 1.5M, which was demonstrated to be more effective than LiOH, NaOH and KOH treatments at the same concentration in the sole interfibrillar swelling region. The porous structure of fibres was studied by inverse size exclusion chromatography to identify mean pore diameter, total pore area and accessible pore volume. The mean pore diameter of fibres was not affected by TMAH treatments, which was analogous to the effects of NaOH treatment. The degree of swelling, carboxyl content using methylene blue sorption method, depth of colour measured after dyeing with C.I. Direct Red 81 and weight loss changed gradually up to 1.5M. Wide angle X-ray diffraction analyses were applied to identify the crystallinity index and crystallite size normal to the 110, 1 (1) over bar0 and 020 planes. Treatment using TMAH suggests new possibilities for the pretreatment of lyocell fibres owing to the usage of lower concentration to gain comparable results with the conventional NaOH treatment without loss in tensile properties and with less decrease in carboxyl content and weight loss.