M. Huson, J. Church, G. Heintze

Merino wool fibres, which show a bi-modal melting peak have been heat treated to different temperatures in a Differential Scanning Calorimeter (DSC). The samples were investigated using optical microscopy, Scanning Probe Microscopy (SPM), analytical Transmission Electron Microscopy (TEM) and Raman spectroscopy. The combined evidence from TEM and optical microscopy strongly supports the hypothesis that the two peaks arise from the sequential melting of the ortho- and para-cortical cells. Raman spectroscopy shows that most of the degradation occurs at temperatures above the melting point, casting doubt on the hypothesis that the second peak is due to degradation. SPM nano-indentation experiments showed, somewhat surprisingly, that there were no significant differences in the mechanical properties of the ortho- and para-cortex after differential melting.

Y. S. Li, P. P. Fu, J. S. Church

The Raman spectra of some nitro-polycyclic aromatic hydrocarbons, including 2-nitroanthracene, 7-nitrobenz[a]anthracene, 6-nitrochrysene, 1-nitropyrene, 6-nitrobenzo[a]pyrene, and 6-nitro-7,8,9,10-tetrahydrobenzo[a]pyrene, have been recorded in the frequency region 1100–1700 cm⁻¹. The stretching vibrational modes for the nitro group in each of these compounds were assigned based on group frequencies, the measured infrared and Raman spectra, the relative spectral intensities, and the Raman depolarization data. From the measured Raman depolarization data, the orientation of the nitro-substituent with respect to polycyclic aromatic hydrocarbon was determined for each of these compounds except 6-nitro-7,8,9,10-tetrahydrobenzo[a]pyrene. The results were correlated with the direct-acting mutagenicity of the nitro compounds according to the hypothesis suggested by P.P. Fu and his co-workers.

B. X. Huang, K. Wang, J. S. Church, Y. S. Li

The combination of electrochemical methods, laser Raman spectroscopy (LRS), surface-enhanced Raman scattering (SERS) and infrared reflection absorption spectroscopy (IRRAS) have been used to demonstrate that a stable passivated film can easily be formed on Nb in 0.15 M NaCl. The composition of the film has been identified to be NbO₂ and different forms of Nb₂O₅. From LRS, the film formed in 0.10 M NaOH has similar composition. A longer exposure of the Nb electrode to air favors the conversion of NbO₂ to the more stable Nb₂O₅ and the transformation of B-Nb₂O₅ to H-Nb₂O₅. In situ analysis of the passivated film in 0.15 M NaCl was carried out by coupling the electrochemical technique with LRS and SERS. The results indicated the presence of different forms of Nb₂O₅ at the metal/solution interfaces.

J. S. Church, J. A. O’Neill, A. L. Woodhead

Vibrational spectroscopic techniques of FT-Raman, mid-infrared attenuated total reflec tance, mid-infrared diffuse reflectance, and near infrared diffuse reflectance are investigated for the quantitative analysis of wool/polyester textile blends. Data sets based on undyed fabric samples are analyzed using both classical least squares and partial least squares approaches. The PLS calibrations based on the ATR and first derivative NIR data are superior with standard errors of cross validation less than 1.5. A validation set consisting of samples extremely different from those in the training set gives standard errors of prediction of 5.2 and 2.4, respectively. These models are used to analyze blended batts and washed fabric samples. Useful results can be obtained independent of such parameters as sample structure and coloration. The complementary nature of these techniques makes their combination valuable as an industrial quality control, monitoring, and trouble shooting tool.

J. S. Church, J. A. O’Neill

The contamination of wool with polymeric material, largely polyethylene and polypropylene is a common problem in the textile industry. It is most efficient that these pieces are detected at an early stage of processing such as immediately after the scour. This work demonstrates for the first time that near infrared spectroscopy in the 1000 to 1700 nm region is a viable technique for the rapid detection of small amounts of hydrocarbon based polymeric contamination buried in the absorbing matrix of loose scoured wool. Initial experiments carried out under stationary conditions demonstrated that contaminants typical of the size found in the wool scouring industry could be detected. Both principal component analysis and soft independent modeling of class analogies were able to discriminate between contaminated areas of loose wool and areas free of contamination. In later experiments the rapid data collection rate of the diode array spectrometer was exploited with the testing of the method with a moving sample. In the dynamic experiments it was found that the limit of detection was lowered but most contamination could still be detected when moving past the NIR beam at a speed of 2 m/min. Several methods for increasing this speed have been investigated.

J.S. Church, A.S. Davie, P.J. Scammells, D.J. Tucker

Lanasol dyes are classed as reactive dyes containing the α-bromoacrylamide or α, β-dibromopropionylamide group. These dyes have been used on chlorinated wool and silk with excellent results. Over the years a significant effort has been made to understand the mechanism of dye fixation and its effects on the properties of wool fibers. This article summarizes current understanding of the chemistry involved when Lanasol dyes are applied to wool.

L. Pille, J. S. Church, R. G. Gilbert

The adsorption behavior of cationic polymer particles onto wool fibers has been investigated in this study. In particular, the role of the lipid layer surrounding the wool fibers and the oxidation of wool has been studied in terms of polymer adsorption. For this, polymer particles consisting of cross-linked polystyrene cores and containing surface ammonium chloride groups have been synthesized. These colloidal particles are solely stabilized through electrostatic repulsion. It was shown that, under the same conditions, no polymer particles are adsorbed onto untreated wool while a monolayer is adsorbed onto wool of which the lipid layer has been removed. Wool oxidized with peroxomonosulfuric acid displays a very similar behavior in terms of wetting characteristics and polymer adsorption to untreated wool, despite an increased amount of cysteic acid on the fiber surface. X-ray photoelectron spectroscopy results indicate that the lipid layer is still intact after this oxidative treatment. A monolayer of polymer particles can be observed on the wool surface after the removal of the lipid layer. The enhanced adsorption of polymer particles onto untreated and oxidized wool from which the lipid layer has been removed indicates that this layer presents a major adsorption barrier for cationic polymer particles.

J. S. Church, J. A. O’Neill, A. L. Woodhead

The contamination of natural fiber yarns with polymeric fibrils is a common problem in the textile industry. This work demonstrates that near-infrared spectroscopy in the 2250 to 2400 nm region is a viable technique for the detection of hydrocarbon-based polymeric contamination in both wool and cotton yarn samples. Both high density polyethylene and polypropylene fibrils typical in size to those found in industry could be detected irrespective of polymer and yarn color. A principal component analysis model based on first-order derivative spectra was developed in which yarns contaminated with polymeric fibrils could easily be separated from pure wool yarns. The spectra obtained from the contaminated regions of the yarns were found to cluster well with spectra obtained from the pure polymeric materials. With the use of soft independent modeling for class analogy (SIMCA), a single class model for wool was developed on the basis of the raw data. This model easily discriminated between pure wool and polymer-containing samples, but the distinction between the different polymer types themselves was poor. This separation was enhanced, however, when the model was based on first-derivative spectra.