S. Fares / Natural Science 3 (2011) 1034-1039
Copyright © 2011 SciRes. OPEN ACCESS
1038
Figure 8. The a.c Conductivity of the Makrofol-E samples
versus radiation doses at various frequency values.
with radiation dose. Furthermore, a sharp increase in
conductivity was observed within the frequency rang (2 -
3.5) MHz. The increase in conductivity due to irradiation
may be attributed to scissioning of the polymer chains,
resulting in an increase of free radicals, unsaturation, etc.
Further more, Figure 8 depicts a linear relation be-
tween conductivity and radiation dose up to 200 KGy.
The empirical equation satisfied by this relation at fre-
quency (0.6 MHz), represented as:
95
7.25 101.2 10D
where (D) in KGy. Which prove that, the induced
changes in electrical conductivity due to gamma irradia-
tion of Makrofol-E provide a better method for gamma
dose measurements.
4. CONCLUSIONS
Makrofol-E polycarbonate films were irradiated with
γ-radiation to study the modification in dielectric proper-
ties induced by irradiation. Ionizing radiation interacts
with polymers via two primary mechanisms, chain scis-
sion to reduce molecular weight and cross-linking to
generate large polymer networks. Both mechanisms oc-
cur and its effects vary from polymer to polymers and to
some degree from part to part, during irradiation, but one
generally dominates. Our experimental results of elec-
trical properties of the Makrofol-E samples prove that,
the samples vary in sensitivity to radiation. That is mean,
Makrofol-E polymer have much greater resistance to
radiation damage, so we suggest Makrofol-E to be used
in medical products applications. It has been observed
that under γ-irradiation, dielectric constant decreases
with frequency whereas dielectric loss shows random
behavior. It increases up to 2.8 MHz followed by a de-
crease up to 3.5 MHz.
5. ACKNOWLEDGEMENTS
The auther sincerely thanks prof. Dr.A.korna and Dr. S.M.Abdou,
Assi.Prof., for research faciliteis and helpful discussions which enabled
this work to be carried out. This work supported by the Departement of
Radiation Physics, National Center for Radiation Research and Tech-
nology (NCRRT), Cairo, Egypt, is also gratefully acknowledged.
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