Research Description
In this paper, three samples of ethylene–propylene–diene monomer rubber (EPDM)/wheat husk fibers
(WHF) with short (SW30), medium (EW30), and long (HW30) lengths of WHF were investigated as a
function of γ-irradiation dose up to 300 kGy. The swelling coefficient Q of the toluene, benzene, and
chloroform solvents was performed, and the Q reflects the ability of the polymer composites to absorb
and retain a solvent within their structure. The conductivity of the examined composites has been
computed, and their dielectric characteristics have been calculated. It was found that the dielectric
constant exhibited frequency-dependent behavior indicating enhanced charge carrier mobility. The
conduction mechanisms in the composites were found to be quantum mechanical tunneling and
correlated barrier hopping, depending on the composite and irradiation dose. The γ-irradiation dose
dependence of the free volume size, deduced from positron annihilation lifetime spectroscopy, is
increasing for the SW30 composite while it decreases for both EW30 and HW30 composites. Increasing
the free volume hole size is connected to the degradation effect on the SW30 samples. For EW30 and
HW30, there is shrinkage of free volume in the composites due to crosslinking induced by γ-irradiation.
Additionally, the nanoscopic properties derived from PAL spectroscopy are correlated with the
macroscopic properties of the composites.
