Interlaboratory tests on polymers by differential scanning calorimetry (DSC): Determination of glass transition temperature (T-g)

The present report presents results obtained form an interlaboratory test, 28 participants, mainly form industry and research institutes, measured gla ss transition temperatures (T-g) by differential scanning calorimetry (DSC) on four different polymers. The materials used were ply(methyl methacrylat e) (PMMA), polycarbonate (PC), polysulfone (PSU) and amorphous polyamide (P A 6I/6T). The measured data were collected by EMPA and were evaluated using a robust statistical method. Repeatability and reproducibility data were o f special interest. The repeatability limit(r) of glass temperatures measur ed according to DIN 53765 was found in the region of 1-2 degreesC, and the reproducibility limit(R) was around 3-4 degreesC. In addition to the DIN st andard, the set of interlaboratory test data was evaluated and considered a ccording to some different approaches adn was correlated with data from oth er EMPA interlaboratory tests performed previously. It was shown that the i nvestigated statistical parameter was always in a similar dimension. The da ta of the PA sample were found to be an exception. Due to the hygroscopic c haracter of polyamide, the r adn R values increase sharply, to and almost t hree times higher reproducibility limit. Overall, the evaluated data can be used to estimate the results of own adn external T-g measurements and thei r compatibility. The report should therefore support daily work ion analyti cal laboratories where glass transition temperatures are measured by DSC.