Examination of optical properties and estimation of mechanical energies of irradiated polypropylene and teflon

Abstract

The optical absorption and mechanical yielding energy has been studied under exposure of γ-radiation. Two crystalline polymers, polypropylene (PP) and Teflon, were irradiated with a ⁶⁰Co source, with doses ranging up to 6 kGy. The observed optical energy gap (E _opt) and energy gap tail (Δ E) for irradiated thin sheets of PP were determined from the measured absorption spectra. The average values of (E _opt) and (Δ E) were 5.85 and 0.5 eV, respectively. There is no detectable change in the optical energy gap under the applied γ-ray doses. On the other hand, the effect of γ-radiation on mechanical properties of irradiated Teflon was much pronounced. It was found that Young’s modulus and yield stress increase with radiation dose, whereas the yield strain decreases. The calculated yield energy increases with radiation dose from 0.27 to 0.35 Mpa per unit volume. The enhancement in the mechanical properties of irradiated Teflon was attributed mainly to crosslinking process and other structural changes occuring during irradiation with γ-rays.

Keywords:

• Optical
• Mechanical
• Energy
• Polymers
• Gamma-ray
• Absorption

Acknowledgements

The authors are grateful to the Atomic Energy Agency in Jordan and Mr Al-Horany for his technical help in irradiation of the samples. The authors also thank Mr M. Gharbie for performing the UV-spectrophotomer work in the Chemistry Department at the Jordan University. Dr S. Saq’an carried out the optical part of this article.