Migration of stabilizers and plasticizer from recycled polyvinylchloride

Abstract

The migration of lead, cadmium, and zinc stabilizers from recycled unplasticized and plasticized polyvinylchloride (PVC) into deionized water (DW), saliva (SAS), and sweat (SWS) simulants was investigated. With the results obtained with DW diffusion coefficients in the plastics and partition coefficients at the plastic‐water interface for these additives were determined. The results indicate that organic stabilizers diffuse faster than inorganic ones in the matrix of the PVC. This fact is confirmed also by the low diffusion coefficients found for antimony oxide used as flame retardant in plasticized PVC. The migration rates of the metal (and especially lead) containing stabilizers from unplasticized PVC in DW are very low due to their low diffusion coefficients in the polymer and low solubilities in water. These migration rates are, as expected, higher from plasticized PVC, mainly because of the higher diffusion coefficients in the polymer. The migration levels of lead stabilizers from PVC into SAS are comparable with those into DW. However, for SWS considerably higher lead migration levels were found, probably due to the ability of the lactic acid and/or ammonium hydroxide components of SWS to coordinate the Pb ions resulting in an increase of the solubility of the lead containing stabilizers in this liquid. Migration of the plasticizer diethylhexyl phthalate (DEHP) from plasticized PVC samples into the same liquids was also investigated. The results obtained indicate that these migration processes are mainly controlled and limited by the low solubility of DEHP in these liquids. No enhanced DEHP migration into SWS was observed. J. VINYL ADDIT. TECHNOL., 24:E112–E124, 2018. © 2017 Society of Plastics Engineers