Factors affecting the deterioration of the cellulosic fibres in black-dyed New Zealand flax (phormium tenax)

Abstract

The fibre from New Zealand flax (Phormium tenax) is destabilized by a commonly used traditional black dye, which is an iron/plant polyphenol complex. By characterizing a variety of old and modern samples it has been shown that low pH and high iron content are responsible for the degradation. As degradation proceeds, the hue changes and the extent of degradation—as measured by water and 1% sodium hydroxide solubilities—increases. The fibre has a high proportion of the non-cellulosic xylan polysaccharide and this contributes to the high rate of degradation because it is susceptible to degradation and releases acetic acid. The rate of degradation in accelerated aging tests was increased by raising the relative humidity.