The Influence of Weathering Conditions in the Evolution of Molecular Properties of Poly(Vinyl Chloride) for Outdoor Applications. An Analytical Study Using Techniques of Surface Analysis (SEM and XPS)

Abstract

In the present work, four different PVC formulations, designed for outdoor applications, were submitted to artificialaccelerated ageing under xenon light, without and with spray of water, and to natural exposure. The influence of the combined action of water and radiation was evaluated by means of surface analysis using XPS, SEM and colourimetry, permitting comparison of the results obtained under different exposure conditions. Results show that a long preliminary period of irradiation ( 2000 h) before the exposure to water increases the resistance of PVC surfaces to weather conditions. The role of that initial irradiation period is to create an erodable layer made of shrunk ‘‘PVC’’ that had lost most of its chlorine atoms and, thence, creating a network of cracks. That layer loses easily adhesion to deeper layers due to erosive action of water spray. The more perfect uncovered surface is better at resisting the effect of radiation.