Characterization of Additives in Polyvinyl Chloride Using Infrared Spectroscopy and Evolved Gas Analysis–Mass Spectrometry Coupled with Two-Dimensional Correlation Spectroscopy

Phthalate-based plasticizers in polyvinyl chloride (PVC) polymer were examined using infrared (IR) spectroscopy and evolved gas analysis-mass spectrometry (EGA-MS), a type of mass spectrometry (MS). IR signals arising from the C=O stretching vibrations of the plasticizers are observed but it is difficult to distinguish individual components due to their structural similarity. In contrast, temperature-dependent mass spectra of the PVC sample revealed a characteristic increase in total ion signals within the 100-220 °C range, indicating that plasticizer desorption occurs predominantly before decomposition of the PVC polymer. The application of two-dimensional correlation spectroscopy (2D-COS) to the mass spectra elucidated the detailed sequence of spectral changes during thermal desorption. The 2D correlation spectra derived from the mass spectra within the 100-220 °C range exhibited distinct correlation peaks associated with bis(2-ethylhexyl) phthalate, bis(2-ethylhexyl) adipate, and bis(2-ethylhexyl) sebacate. These results demonstrate that EGA-MS, combined with 2D-COS, can effectively identify individual additives in polymer systems.