Temperature Dependent ESR Spectra of Irradiated Nylon Homopolymer

Author(s): S. Kalahasti, B. Sanjeeva Rao, T. Venkatappa Rao, J. Saptagiri Prasad, K. Madhukar and A. Raju

Temperature dependent free radical decay behavior in irradiated nylon homopolymer has been investigated by electron spin resonance (ESR) and Fourier transform infrared (FTIR) techniques. The ESR spectrum observed for nylon irradiated to 1 M rad radiation dose has shown a complex shape and eight hyperfine lines. The spectrum is analysed by computer simulations and resolved to be superposition of component spectra arising due to macroradicals of the –CH2- ⋅C H-CH2~(I) and radicals of the type ~CH2- ⋅C =O (II). The magnetic parameters corresponding to the free radicals were evaluated by theoretical methods. ESR spectra of irradiated nylon were also recorded in the temperature range 300-400 K. The hyperfine structure observed at room temperature (RT) gradually diminished and the ESR signal completely vanished around 405 K. Reasons for this temperature dependent free radical decay has been explained. Fourier Transform Infrared (FTIR) spectra of unirradiated and irradiated nylons were recorded to ascertain chemical changes induced by radiation.

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