Quantification of sulfur distribution on rubber surfaces via µ-x-ray fluorescence analysis

The μ-XRF is a tool to image the distribution of chemical elements. The quantification of these pictures is initially difficult for polymers because their main components C and H cannot be detected with this method. In this article, a way to solve this problem was shown. For this purpose, the amounts of substances of the not detectable elements were determined and used as correction parameters for the quantification with the fundamental parameter method. With this supplemented fundamental parameter method, the sulfur content can be quantified very accurately: The results fit very well with the expected theoretical values. In addition, the sulfur concentrations were confirmed by the independent method 832 Series sulfur/carbon determinator by LECO. With the problem of quantification now solved, μ-XRF has a wide range of potential applications in the rubber field: The evaluation of sulfur homogeneity on elastomer surfaces of several cm₂ can now be displayed in a statistically reliable manner. This allows conclusions to be drawn about compounding quality. Other conceivable applications include investigations of the blooming or diffusion behavior of sulfur or other chemical elements. This is particularly interesting when different compounds accumulate in a product such as tires or recycled material.