Fig. 5 shows the variation of swelling number SN
as a function of irradiation dose for NBR/EPDM
(50/50) blend and its composites that are loaded
with different contents of HAF carbon black up to 100 phr, in car oil as oil medium. It can be seen that
values of SN attained by all compositions have
decreased, almost semi linearly on increasing the
irradiation dose. Moreover, unloaded blend has
attained higher SN value over the entire range of
irradiation with respect to loaded composites whose
SN values have decreased with increasing the degree
of loading with the filler on comparing these values
at the same irradiation .These data indicate clearly
that the prepared vulcanized composites possess
better resistance to be swelled by car oil, with
respect to NBR/EPDM blend alone. Apparently,
the presence of the filler particles in its aggregate
‘‘structure’’ form with the formation of interphase
chemical as well as physical bonding on vulcanization
has contributed effectively to the above mentioned
behavior.