Comparison of the effects of various presettings on the colour of polyamide 6.6 dyed with acid dyestuffs

Polymeric fibres are semicrystalline structures in which the macromolecules are rarely oriented in their equilibrium state. Further instabilities are imparted when the fibres are converted to yarns and the yarns to fabrics. Heat-setting is an important industrial process, as it reduces the fibre strain to an acceptable limit. This paper presents results of a study on the effects of various presettings (heat-, steam- and hot water-setting processes) on the dyeing properties of polyamide 6.6 fibres with acid dyestuffs. It was found that the colour yield is lower for dyed samples after dry heat-setting, but in the case of samples that have been hot water-set or steam-set, the colour yield increases slightly for light shades and remains constant for dark shades, compared with the unset dyed sample.