Analysis of Cross-Section Structure of a Polymer Wrapping Film Using Infrared Attenuated Total Reflection Imaging Technique with an Aid of Chemometrics

Abstract

Infrared microscopic imaging techniques with an aid of augmented alternative least-squares (ALS) regression analysis have been employed for analyzing the interface structure involved in two wrapping films that have a common layered structure with different adhesive intermixing between the adjacent layers. A conventional single-band mapping technique exhibited a problem that the imaging results responded to the selection of an analytical band. On the other hand, the augmented ALS technique has proved to powerfully decompose the collection of spectra into spectroscopically independent spectra and quantity variations in the mapping area. Regardless, the chemometric analysis could not commonly be applied to the two films, and different pretreatments were necessary for analysis of the two films. As a result, the concentration profiles across the boundaries have readily revealed that the two films have largely different adhesive structures. In addition, the structural difference was found to be a reason an identical analytical technique cannot be employed for analysis of the two films. This study shows an appropriate pretreatment and selection of a chemometric technique considering the samples that have different spectroscopic characters are of great importance for effectively draw map images and pure-component spectra of the constituents.

Molecular structural analysis of hydrated ethylene glycol accounting for the antifreeze effect by using infrared attenuated total reflection spectroscopy

“…To obtain chemically independent spectra from the concentration dependent IR spectra, alternative least-squares (ALS) regression were performed after principal component analysis (PCA) [15,16], which can estimate the number of constituents. In the analysis of time-resolved spectra without an accumulation, the spectral noise was significantly reduced by the use of PCA, which were used for the classical least square (CLS) regression analysis.…”

Determination of pH Dependent Structures of Thymol Blue Revealed by Cooperative Analytical Method of Quantum Chemistry and Multivariate Analysis of Electronic Absorption Spectra

“…These two factors are called "basis factors," whereas the rest ( j ² 3) are called "noise factors." Although two basis factors are almost enough to explain the color change of TB solution, the "augmented" ALS techniques, 8,14,21 which were employed in the present study (mentioned in the next subsection), require additional factors to the basis factors to obtain the independent electronic absorption spectra of TB for the red and yellow forms. Therefore, the spectra were reconstructed to discard noise by using the first 5 factors (eq (4)).…”

“…The noise-reduced pHdependent electronic absorption spectra were subjected to spectral decomposition, the augmented ALS regression, into two pure-component spectra. 8,14,20,21 ALS is a CLS-based technique as formulated as follows in the case of the present study. 8,14…”

Application of principal component analysis for improvement of X-ray fluorescence images obtained by polycapillary-based micro-XRF technique

“…As shown in Fig. 3(d), the data matrix-A can be expressed with the following equation 1using the eigenvectors (p) and score vectors (t) [9][10][11][12].…”