Crystallinity in EPDM terpolymers

Abstract

AbstractThe crystallinity of a series of ‘medium‐high’ green strength EPDM terpolymers has been examined by X‐ray diffraction and thermal analysis. It has been found that the crystallinity of such materials can vary from 0.20% as measured by thermal analysis, and depends on the E:P ratio in the polymer. It is also suggested that it depends on the distribution of E and P units. An explanation for the differing results obtained by thermal analysis and X‐ray diffraction has been proposed. The time taken to achieve maximum crystallinity varied for the series of polymers examined, and the improvement of crystallites continued over extensive periods of time. The final level of crystallinity in the polymers and the rate of changes occurring was temperature dependent. For one sampel (‘Nordel’ 1560) it was shown that crystallinity affected mechanical properties.