Abstract
The IR and Raman spectra for a series of traditionally black-dyed (with iron-tannate) harakeke (New Zealand flax, Phormium tenax) fibres have been measured. Such fibres are used to make numerous cultural materials by indigenous (Māori) communities in New Zealand. The fibres were subjected to artificial light-aging to determine the changes that occur due to fibre degradation. Fibres could be distinguished using IR spectroscopy based on whether they were dyed, and which form of iron-tannate dye was used, made with either a condensed or hydrolysable tannin (hinau, Elaeocarpus dentatus or manuka, Leptospermum scoparium). Raman spectroscopy differentiated dyed and non-dyed fibres and the type of dye based on the nature of the tannins used. For IR spectroscopy, it was possible to observe spectral changes with aging for the non-dyed and hinau-dyed samples. For non-dyed fibres the aging changes reflected an increase in cellulose crystallinity. For the hinau-dyed samples, the changes appeared to reflect increased oxygen content and higher acidity levels. These are important constituent changes that lead to degradation of fibres.
• Harakeke fibres (Phormium tenax) have been characterised using Raman & IR spectroscopy.
• Fibre degradation occurs with artificial aging methods.
• Dyed fibres may be characterized with Raman spectroscopy.
• Fibre strucutre with aging may be seen with infrared.
• Spectroscopic markers for increased acidity and cellulose crystallinity are observed.