Application of Bloch Analysis to Evaluate Activation Energy from Temperature Dependent ESR Spectra of Irradiated PET

Author(s): K. Rajendra Prasad, D. E. Kalpana Rani, E. Venkateswar Rao, Ch. Srinivas, S. Kalahasti and B. Sanjeeva Rao

Gamma irradiation of poly (ethylene terepthalate) (PET) results in formation of different types of free radicals. Identification of free radicals has been done by recording ESR spectra of irradiated PET. Effect of temperature on the decay of free radicals has been investigated. The free radicals produced in irradiated PET are found to decay around 410 K. Activation energy corresponding to free radical decay has been evaluated using Bloch analysis. Using this method, a plot has been drawn 1/T values and log τ. The slope of the curve gives activation energy. The value of activation energy obtained by this method is very high suggesting the thermal stability of free radicals produced in PET.

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