| dc.description.abstract | Thermal conductivities of EPDM (ethylene propylene
diene monomer) rubber loaded with one of the following
fillers: carbon black type N339, a reinforcing filler,
kaolin, a non-reinforcing filler, and ground charcoal
have been studied using a guarded hot plate apparatus
designed at Kenyatta University. The hardness and
tensile strength as well as the breaking energy of the
composites have also been determined.
The results show that the thernal conductivity, k
increases with increasing filler concentration in the
composites. The thermal conductivity values also
increase with increasing composite hardness. Thermal
conductivity and tensile strength values were higher
for the composites filled with a reinforcing filler
than those filled with non-reinforcing ones. The high
values are explained in terMS of the filler-polymer
interaction energies that are higher in composite filled
with reinforcing fillers than those filled with the
non-reinforcing ones.
Using several known therMal conductivity models,
for bicomponent composites, the theoretical values of
thermal conductivity were calculated for the various
filler concentrations and compared with the
experimentally determined values. None of these models,
su~cessfully predicted the experimental values of
thermal conductivi.ty of rubber composites. In almost
all the cases the theoretical values of k for
kaolin, charcoal and carbon black samples are at
variance with the experimental values. Explanation for
this discrepancy is based on the fact ~hat the polymer
filler interaction-parameter which is different in the
three fillers used, plays an important role in
facilitating thermal conductivity in the composites.
Besides other results, the conductivity-hardness and
tensile strength results confirm this observation.
As a major finding of this work, it is observed that
the theoretical models available have been derived on
the basis of conductivities of the individual
components, they do not incorporate the interaction
parameter which apparently plays an important role in
rubber composites. | en_US |
