Broadband FIR absorption spectra of low‐density polyethylene sheets containing six different antioxidants and estimation of their contents by chemometric analysis

Abstract

Antioxidants are usually added to polymeric insulating materials to suppress oxidative degradation. However, the details of antioxidant added to a polymer are often not disclosed. On the other hand, compared to mid-infrared absorption spectroscopy, terahertz (THz) absorption spectroscopy, and far-infrared (FIR) absorption spectroscopy have not been performed so often. Based on the above backgrounds, six different kinds of antioxidants were added into low-density polyethylene sheets with four different contents, and their THz and FIR absorption spectra were measured. As a result, it has become clear that each antioxidant shows its specific absorption peaks, by which the antioxidants can be identified. Furthermore, the antioxidant content can be estimated by the absorption intensity of the specific peak. A chemometric analysis can make the estimation more accurately than a simple comparison of absorption intensity.

Optical sensing in condition monitoring of gas insulated apparatus: a review

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Quantum chemical verification of identification of three phenol-type antioxidants by far-infrared absorption spectroscopy

“…From such a viewpoint, we obtained FT-FIR and THz spectra for more than seven kinds of antioxidants and reported that the two spectroscopic analyses have a potential ability to identify antioxidants even if they have similar structures. [21][22][23][24][25] Furthermore, we have demonstrated that a chemometric analysis can make the identification more reliably even if we do not know a reference spectrum of a pristine polymer with no anitioxidants. 24,25) However, we have not confirmed that the spectra we had obtained truly reflect the molecular structure of each antioxidant.…”

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