Migration of plasticizers from flexible PVC: Monitoring the concentration profiles by confocal Raman microspectroscopy

This study introduces and validates an effective approach for monitoring the plasticizer amount and its concentration profile in polyvinyl chloride (PVC) formulations. The method combines gravimetric measurements with confocal Raman depth profiling analysis. Several flexible PVC (pPVC) formulations were compared in this study, including: pPVC@DEHP, using the monomeric plasticizer di(2-ethylhexyl) phthalate (DEHP); pPVC@PBA, using the polymeric plasticizer poly(butylene adipate) (PBA); and crosslinked pPVC (cPVC@DEHP), where isophorone diamine (IPDA) served as the crosslinker. Migration tests were performed according to UNI EN ISO 177 standard. Spectroscopic findings were correlated with gravimetric data, highlighting strong differences in the migration behavior among the formulations. The results demonstrate the effectiveness of the proposed method in quantifying plasticizer leaching and obtaining detailed concentration profiles at fine scale.