Terahertz spectroscopy for rubber production testing

The interest in new test methods for rubber production has been growing rapidly over the past years. Recent developments in production planning aim to minimize storage times, and hence limit the time available for process control between production steps. New additives such as silica and carbon nanotubes allow for significant improvements in the material quality. Both developments demand new approaches to control the production process where established methods do not work satisfactorily. In this study, we have investigated the capability of terahertz time-domain spectroscopy as a new tool for rubber production testing. Offline measurements of different material families show a strong contrast in the terahertz refractive index. Inline measurements during elastomer extrusion allow for monitoring production processes and the duration of purposely induced material changes in the extruder. This technique helps to improve the quality of the materials and to minimize waste.