ELECTRON-SPIN-RESONANCE STUDY OF GAMMA-IRRADIATED POLY(METHACRYLIC ACID)

Low temperature relaxations in poly(methacrylic acid) (PMAA) have been studied by electron spin resonance (ESR) spectroscopy. The observed 8 line ESR spectra of irradiated PMAA in the temperature range 77-300K (LNT-RT) is attributed to the free radicals of the type approximately CH2 - C.H - CH3. Assignment of ESR spectra to free radicals has been m ade on the basis of magnetic parameters employed to simulate ESR spect ra at different temperatures. Further, ESR spectra below LNT have been simulated, using the set of parameters employed to simulate the exper imental spectrum at LNT. Magnetic parameters of the ESR spectra at LNT and below LNT indicate gamma- and delta-relaxations of PMMA chains. ( C) 1994 John Wiley & Sons, Inc.