Problems of ageing and stabilization of poly(vinyl chloride)

We have investigated plasticized poly(vinyl chloride) (PVC) samples aged in natural and artificial conditions, and samples recovered after use for a long time (15-30 years) at 253-301 K. The predominant process in dark, low temperature ageing of plasticized PVC is loss of plasticizer by desorption. In photo-ageing the main process is degradation of both polymer and plasticizer, proceeding generally on the irradiated side of the sample and depending on the spectral distribution of the light. Washing off of stabilizers from the polymer occurs in contact with water. With consideration of the experimentally determined empirical kinetic equations for mass loss or degradation during use or artificial exposure we can determine the conditions of ageing. Based on an analysis of the use conditions, one can deduce predictive equations for the description of degradation. (C) 1996 Elsevier Science Limited