ELECTRICAL AND PHYSICAL-PROPERTIES OF ETHYLENE-PROPYLENE-DIENE MONOMER (EPDM) RUBBER LOADED WITH SEMI-REINFORCING FURNACE BLACK

The physico-mechanical properties have been investigated of ethylene-propylene-diene monomer (EPDM) rubber samples loaded with semi-reinforcing furnace black (SRF) in quantities up to 60 phr. It is shown that increase of SRF content increases the tensile strength and decreases the elongation at break and equilibrium swelling. The permittivity epsilon' and the dielectric loss epsilon'' for these samples were determined in the frequency range 100 Hz to 10 MHz. epsilon' was found to increase with increasing carbon content and showed anomalous dispersion. At a certain concentration of SRF black, an abrupt increase in epsilon' and epsilon'' was noticed. This could be ascribed to some sort of interaction between the rubber and the SRF at higher concentration. The absorption spectra were analysed into three Frohlich terms for both unloaded and loaded samples. The first term, in the lower frequency range, could be attributed to the Maxwell-Wagner effect, while the second and third terms in the higher frequency range may be due to the orientation of the large and small aggregates caused by movement of the main chain. The samples under investigation were subjected to thermal ageing for different periods of time, the measurements were reinvestigated and the data obtained interpreted.