MICRO-INDENTATION TESTING WITH DISPLACEMENT RATE CHANGES APPLIED TO PHYSICAL AGEING OF PAINTS AND PROPERTIES OF ABS

摘要

Micro-indentation with precision displacement rate changes was used to determine the activation volume of polymeric polished cross-sections and coatings. In the un-pigmented clear ABS, the hardness changes with depth were much smaller than those with the activation volume. It was then hypothesized that the thermally activated portion of the flow stress can be separated from the athermal part and a self-consistent model was developed. In the case of silica modified polyester paint, the hardness increase with depth was correlated to the effective increase in the fraction of the particles with increasing deformation volume. The ageing of the polyester could be clearly demonstrated with large reductions in the activation volume with time.