New Methodology Development for Quantification of Additive in Polyolefins Using Infrared Spectroscopy and X-ray Fluorescence Spectroscopy Analytical Techniques

Abstract

To ensure that the specified amount of an additive or combination of additives is incorporated into a polymer after the extrusion process, a rapid and accurate analytical method is required. Quantification of additives in the polymer is necessary, since the additives may degrade and the amount of additives can influence the physical nature of the polymer. The accurate and reliable measurement of antioxidant content in polymers by chromatographic techniques, e.g., liquid chromatography (LC) is an important tool in quality and manufacturing control, troubleshooting, and material or vendor identification. The major difficulty in the characterization is usually not the analytical method but rather the separation of the antioxidants from the polymer matrix. Conventional extraction techniques for polymer additives, such as, Soxhlet or dissolution / precipitation are labor intensive, time consuming, expensive, and the optimal recovery is significantly less than 90 percent. Therefore, more complex and efficient methods with the possibility of working at elevated temperatures and pressures have been developed, i.e., microwave-assisted extraction (MAE), supercritical fluid extraction (SFE) and accelerated solvent extraction (ASE). The present research employs MAE for the extraction of additives, i.e. Irganox 1010 and Irgafos 168 from high density polyethylene (HDPE) followed by HPLC/UV concentration analysis. Further, calibration models have been devised against the HPLC concentration (reference) for the additives using Infrared spectroscopy & X-Ray Fluorescence characterization techniques. These calibration curves can be used for swift analysis of quantification of additives in HDPE without undergoing tedious extraction and chromatographic procedures during quality control.