Dynamic mechanical analysis and Vickers micro hardness correlation for polymer coating UV ageing characterisation

The aim of this study is to investigate UV ageing of a paint system by means of two types of mechanical analysis. In a first step, UV irradiation was studied by investigating the glass transition temperature (T-alpha) of each coat. A new method based on dynamic mechanical analysis (DMA) was studied using a single cantilever test. We can observe that the surface coat is aged, whereas the primer layer is not affected. A simple equation is proposed to correlate this kind of evolution versus exposure time. In a second step, the UV ageing was studied by Vickers micro hardness (Hv) test. Hardness of the surface coat increases with exposure time. This evolution versus time is controlled by the same relationship as before. In this way, we have shown that a linear correlation can be drawn between T-alpha results and micro hardness measurements: H nu =A.T-alpha+B. (C) 2001 Elsevier Science Ltd. All rights reserved.