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Fractional Free Volume Dependence of Neutron-Irradiated Polystyrene (PS) Measured by Positron Method | ||
| Iraqi Journal of Physics | ||
| Article 1, Volume 7, Issue 10, 2009, Pages 35-39 | ||
| Author | ||
| A. A. Al-Bayati | ||
| Abstract | ||
| The fractional free volume (Fh) in polystyrene (PS) as a function of neutron -irradiation dose has been measured, using positron annihilation lifetime (PAL) method. The results show that Fh values decreased with increasing n-irradiation dose up to a total dose of 501.03× 10-2 Gy. A percentage reduction of 2.14 in Fh values is noticed after the initial n-dose corresponding to a percentage reduction in the free volume equal to 42.14/Gy. The total n-dose induces a percentage reduction of 7.26, corresponding to a percentage reduction of 1.45/Gy. These results indicate that cross -linking is the predominant process induced by n-irradiation. The results suggest that n-irradiation induces structure changes in PS, causing cross-linking in PS chains, whereas the presence of oxygen during irradiation causes retardness of cross-linking yield, which consequently affects the values of the above mentioned parameter with respect to their values in case the irradiation is performed in vacuum. | ||
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