Composition, temperature and radiation induced changes in gamma irradiated AAAMPS copolymer

Abstract

Effect of composition, temperature and radiation dose in gamma irradiated acrylamide-2-acrylamido-2-methyl propane sulphonic acid (AA) copolymer has been investigated by electron spin resonance (ESR) and fourier transform infrared (FTIR) techniques. ESR spectra of gamma irradiated AA copolymer have been recorded under different conditions. The observed ESR spectra are analysed by computer simulation techniques, to separate the constituent component spectra. Magnetic parameters employed to simulate the component spectra enabled the identification of corresponding free radicals. The AA copolymer with low acrylamide content composed of macroradicals of the type ‒CH₂‒CH‒CH₂‒ and methyl radicals (CH₃) whereas the copolymer with high acryl amide content possess methyl radicals and radicals of the type ‒CH₂‒C(CONH₂)‒CH₂‒/CH₃‒C‒CH₃. Reasons for the variation in the formation of free radicals have been explained. The observed changes in ESR spectra of irradiated AA copolymer at higher temperatures are thought to be due to the recombination of free radicals. Formation of free radicals found to be enhanced with the increase in dose of irradiation. FTIR spectra of pure and irradiated copolymers have also confirmed the previous results.

Keywords:

• AA copolymer
• ESR spectra
• Composition variation
• Temperature and dose dependency of free radicals

Acknowledgements

The authors wish to acknowledge the help of Professor T.K. Gundu Rao and Dr. Vrindha for recording ESR spectra at the SAIF (Sophisticated Analytical Instrumental Facility), Indian Institute of Technology, Mumbai. Encouragement of Sri. S. Lakshmana Chary, Tax Consultant Hanamkonda is highly acknowledged.