Study on the Internal Motions of Some Acryl- and Methacryl-group High Polymers by Pulsed NMR Method

The internal motions of some high polymers were investigated by measuring the spin-lattice relaxation time ( T 1 ) together with its minima ( T 1 min ) in proton resonance in the temperature range from liquid air up to about 300°C by pulsed NMR method at 25 Mc/sec. For acryl-group high polymers (PMA, PEA, PEA), two minima of T 1 were observed, one at higher temperature corresponding to the segmental motion and the other at lower temperature to the internal motion of side chain ester alkyl group. For methacryl-group high polymers (PMMA, PEMA, PBMA), three minima of T 1 were observed, of which one at the highest temperature corresponds to the segmental motion, the next at the middle temperature to the internal motion of both main chain methyl group and side chain ester alkyl group and the last at the lowest temperature to the internal motion of the latter group alone. Thus, we could definitely separate the internal motion of amorphous high polymers. The rigorous analysis of the behavior is considered to be a rather difficult problem, because of the complexity of the circumstances and the lack of both existing suitable formulas and precise experimental data.