DETERMINATION OF FINISHING OILS IN ACRYLIC FIBERS BY NEAR-INFRARED REFLECTANCE SPECTROMETRY

The potential of near-infrared diffuse reflectance spectrometry for qu ality control analyses in the textile industry was explored with a vie w to the quantification of finishing oils in acrylic fibres by partial least-squares regression, using a rotary cuvette system for recording spectra, Calibration was performed with a set of samples that encompa ssed every source of variability (linear density of the fibres, colour , concentration of the finishing oil), and the wavelength region where absorption was mostly due to the oil was used to construct several mo dels from which that leading to the minimum relative standard error fo r a sample test set was selected, The results provided by various math ematical treatments [second-derivative, standard normal variate (SNV)] used to minimize scattering resulting from the differential linear de nsity of the samples revealed no significant differences between predi ction errors (only in the number of partial least-squares components), The model was used to quantify levels of finishing oil in routinely m anufactured samples for a period of 6 months, during which time two ba tches showed poor predictions due to a new component appearing in the product, Modification of the calibration model to account for this com ponent substantially increased robustness and allowed the accurate qua ntification of all batches manufactured after the model has been devel oped.