QUANTIFICATION OF A VITAL NUCLEATING AGENT FOR IMPROVING THE RECOVERY RATE OF RECYCLED ETHYLENE-PROPYLENE IMPACT COPOLYMER PLASTICS USING VIBRATIONAL SPECTROSCOPY AND MULTIVARIATE ANALYSIS

The potential of mid-infrared (MIR) spectroscopy as a tool for quantifying the presence of nucleating additives in copolymers has been evaluated. This study focused on the analysis of the Millad NX8000 additive in an ethylene-propylene copolymer using MIR vibrational spectroscopy. The spectral range evaluated was 400 cm -1 - 4000 cm -1 . Univariate and multivariate analyses of the spectral data were performed to evaluate MIR spectroscopy as an analytical technique for the vibrational quantification of additives in copolymers. The results showed that it could be used to build analytical methodologies for the identification and quantification of selected chemical targets, with a highly linear response for concentrations up to ~ 4000 ppm. Four vibrational bands were evaluated in the Millad NX800 absorbance spectrum to determine the figures of merit from the linear regressions. The lowest concentration of additive that could be detected (LOD) was determined to be 241 ppm, and the value for the quantification limit (LOQ) was 804 ppm. Multivariate analysis (MVA) using PLS was applied to the spectral information. The root mean square error of cross-validation (RMSECV), root mean square error of prediction (RMSEP), coefficient of determination from cross-validation (R 2 -CV), and coefficient of determination from prediction (R 2 -Pred) were calculated and used as indicators of the quality of the obtained spectral correlations. The results suggest that MIR spectroscopy could be a useful tool for the quantitative analysis of copolymers with nucleating additives such as Millad NX8000. Keywords: Polypropylene, Copolymer, Multivariate Data Analysis, Partial Least Square Regression, Fourier Transform Infrared Spectroscopy, Limit of Detection, Millad DOI： https://doi.org/10.35741/issn.0258-2724.58.5.40