NIR Characterization and Measurement of the Cotton Content of Dyed Blend Fabrics

Near infrared (NIR) techniques for the measurement of cotton-polyester (PET) blend content have concentrated on yarn slivers and greige fabrics rather than the more difficult application to dyed or printed fabrics. The need for a robust and rapid measurement of the fiber content in dyed cotton-PET fabrics has been expressed by several organizations. Investigations were initiated to develop NIR techniques to measure the cotton content of dyed blend fabrics. NIR measurements were made on dyed or pigmented cotton-PET fabrics that comprised a wide range of cotton content, fabric parameters, and patterns/colors. The samples were analyzed on two NIR instruments at two locations with various reflectance NIR sampling systems. Significant spectral differences were observed for 100% cotton and 100% PET samples, and these spectral differences carried over to the dyed cotton-PET samples with changing cotton content. The impacts of significant differences in baseline were minimized with the use of advanced chemometric normalization techniques. Rapid (less than 5 minutes) and accurate NIR measurements of the blend content in dyed cotton-PET fabrics were developed, with a NIRlaboratory method agreement normally within ± 3.0% cotton for nearly 90% and higher of the validation samples.