Plasticiser migration and structural changes in an aged poly(vinyl chloride) coating

A filled PVC coating used for the head and armrests of trains was aged natu rally in a railway environment or artificially. Ageing caused the coating t o harden and in most cases to crack. The loss in suppleness was linked to t he PVC matrix's loss of plasticisers. Two parameters were studied by artifi cial thermal ageing carried out at about 100 degreesC: the role of the temp erature inside the train, and the influence of the polyurethane foam inside the arm and headrests on the migration of the plasticisers. The loss in pl asticisers, which led to hardening, was accompanied by a structural heterog eneity in the filled PVC matrix. The mineral fillers, initially spread out evenly, were concentrated in one part of the matrix due to the formation of non-filled PVC nodules. Under these ageing states, the material cracked in response to the mechanical constraints caused by the users. (C) 2001 Elsev ier Science Ltd. Al rights reserved.