Evaluation of the glass transition temperature of EPDM using a dynamic mechanical analyser

The glass transition temperature characteristics of polymer materials as a function of temperature are very important issues in sealing between various components. It is essential to establish techniques and measurement procedure to evaluate their thermo-mechanical properties. In this study, the glass transition temperature evaluation procedure and experimental results of the ethylene propylene diene monometer (EPDM), a highly functional special synthetic rubber, are discussed using a dynamic mechanical analyser (DMA). The relative standard uncertainties of repeatability and reproducibility in the glass transition temperature measurement of EPDM were evaluated by extrapolation method of the sample heating rate according to the ISO standards. For commercial EPDM, 10 specimens in the same batch were processed in vertical and horizontal directions to measure the reproducibility of the glass transition temperature measurement. The relative standard uncertainties for the repeatability and reproducibility of the glass transition temperature were 1.4% and 1.7%, respectively. In addition, the glass transition temperature was measured for 5 types of samples while increasing the addition of plasticiser to the EPDM samples (from 0 phr to 40 phr). As the addition of plasticiser increased, the glass transition temperature decreased by 75% effectively. In conclusion, Tg evaluation can be performed well in a very low temperature range (about -70 degrees C) using DMA, which is a temperature range that corresponds to the use range of polymer materials applied in industry.