Computer aided rheological characterization of polymer melts

The next generation of software for the theologist will not only convert data but also analyze the data for consistency and limits of application. Rheometry has grown into a mature field, mostly through advances in rheometer hardware combined with computer interfacing and data analysis. With ease, we can subject samples to well defined transient stresses and/or strains and not only measure the response but analyze it with interactive computer graphics. After that, we may simply use the data as obtained or we can ask further questions concerning data quality, completeness of the data set and limitations of applicability of the data. It is essential that these questions do not get neglected when the ease of data processing might give a false impression of safety. The result of such neglect could result in an overinterpretation of the data and a temptation to get drawn into conclusions which, upon closer inspection, are based on experimental artifacts. More advanced methods have to be developed which not only convert experimental data into some reduced parameter set but also show the inherent limitations of the result. This problem will be addressed in the following, mainly focusing on the calculation of the relaxation time spectrum from measurements in the rheometry laboratory.