effects of electron beam irradiation on properties of etfe insulated ...

Effects <strong>of</strong> Electron Beam Irradiation on Properties ... Park E-S
and the EB <strong>irradiation</strong> <strong>effects</strong> on the microstructure,
electrical, mechanical and thermal properties <strong>of</strong>
extruded wire were investigated. When the ETFE
insulated wire was exposed to EB <strong>irradiation</strong>, BDV
and ρ I were decreased gradually with increased EB
<strong>irradiation</strong> dose. This was due to EB <strong>irradiation</strong>
induced chemical changes in polymers creating weak
pathways and they reduced ρ I and accelerated
dielectric breakdown. SEM Observation confirmed
that the original wave texture was disappeared and
many voids were emerged at the fracture surface <strong>of</strong>
ETFE-15 and ETFE-20. TGA Traces showed that the
thermal stability <strong>of</strong> EB-irradiated ETFE samples
decreased significantly compared with pristine
ETFE. After EB <strong>irradiation</strong> the tensile properties and
scrape abrasion resistance <strong>of</strong> the extruded wire
samples also decreased with <strong>irradiation</strong> dose. The
reduction <strong>of</strong> thermal stability and mechanical
properties was considered to be due to macromolecular
chain scission induced by EB <strong>irradiation</strong>. FTIR
Spectral analysis showed that in EB-irradiated
samples, the formation <strong>of</strong> -C=O and -C=C- groups
can be identified and their amplitude is increased
with <strong>irradiation</strong> dose. Moreover, the intensity <strong>of</strong> the
band at 2985 cm -1 is decreased with increasing
<strong>irradiation</strong> dose, which could be an indication <strong>of</strong>
cleavage <strong>of</strong> C-H bonds. After thermal aging the
colour <strong>of</strong> copper conductor <strong>of</strong> EB-irradiated wires
was turned yellowish. It can be explained that EB
<strong>irradiation</strong> could promote dehydrogenation <strong>of</strong> ETFE
at a lower temperature compared with pristine ETFE.
After EB <strong>irradiation</strong>, the T m and T c <strong>of</strong> ETFE fall
gradually with <strong>irradiation</strong> dose, whereas χ is slightly
increased up to 5 Mrad and it is decreased
significantly thereafter. Upon EB <strong>irradiation</strong> in the
presence <strong>of</strong> a copper conductor, ETFE is prone to
reactions such as chain scission, formation <strong>of</strong>
unsaturated bonds and oxidation, resulting in less
crystalline perfection and consequently lower T m and
T c .
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