Identification and quantification of phenol-type antioxidants in low-density polyethylene by broadband far-infrared spectroscopy

Three kinds of phenol-type antioxidants, BHT, Irganox 1010, and Irganox 1330, were added to sheets of low density polyethylene (LDPE) and their absorption spectra were measured at terahertz and far-infrared frequencies. As a result, absorption with various peaks characteristic to each antioxidant appears. Most of these peaks increase monotonically with an increase in content of antioxidant, by which we can identify and quantify each antioxidant added in LDPE. In addition, by applying a partial-least squares regression method to the whole spectrum, the quantification of antioxidant can be improved.