Discrimination of Nylon Polymers Using Attenuated Total Reflection Mid-Infrared Spectra and Multivariate Statistical Techniques

Abstract

Nylons are an important class of synthetic polymers, from an industrial, as well as forensic, perspective. A spectroscopic method, such as Fourier transform infrared (FT-IR) spectroscopy, is necessary to determine the nylon subclasses (e. g., nylon 6 or nylon 6,6). Library searching using absolute difference and absolute derivative difference algorithms gives inconsistent results for identifying nylon subclasses. The objective of this study was to evaluate the usefulness of peak ratio analysis and multivariate statistics for the identification of nylon subclasses using attenuated total reflection (ATR) spectral data. Many nylon subclasses could not be distinguished by the peak ratio of the N-H vibrational stretch to the sp(3) C-H(2) vibrational stretch intensities. Linear discriminant analysis, however, provided a graphical visualization of differences between nylon subclasses and was able to correctly classify a set of 270 spectra from eight different subclasses with 98.5% cross-validated accuracy.

Surface energetics, dispersion, and nanotribomechanical behavior of POSS/PP hybrid nanocomposites

“…Absorbances at 2916 to 2950 cm À1 corresponding to À ÀCH 2 asymmetric stretching vibrations are observed in all samples, as would be expected based on the structure of the materials. 34,35 In parallel to the morphological and compositional changes observed for the POSS/polymer nanocomposites, dramatic changes in surface mechanical and physical properties were observed. LFM was employed to evaluate nanoscale relative friction and adhesion of the nanocomposite materials.…”

Dyeing of Polyester and Polyamide Synthetic Fabrics with Natural Dyes Using Ecofriendly Technique

“…The CH 2 symmetric and asymmetric stretching were found at 2930 and 2854 cm −1 , associated at 720 cm −1 with the vibration of 4 or more -CH 2 groups in the polymer chain. The band at 1634 cm −1 is associated with the C=O stretching and the 1535 cm −1 band is due to a combination of the bending N-H band and the stretching of the C-N [20][21][22][23][24][25]. It is clear that the intensity of C=O and CO increased due to the UV/Ozone irradiation while the other characteristic groups were slightly degreased.…”

Forensic identification of elephant and giraffe hair artifacts using HATR FTIR spectroscopy and discriminant analysis

“…Discriminant analysis of spectral data has been comprehensively reviewed by Enlow et al (2005). The rationale of discriminant analysis in the present situation was to establish discriminant functions from known keratin standards (i.e.…”