Study of Vinyl Polymerization by Proton Magnetic Relaxation

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Abstract
A study of molecular motion during the process of polymer formation has been performed with measurements of proton magnetic relaxation. The presence of two distinct relaxation processes for the protons of the monomer molecules and those of the polymer chains has been observed. During the polymerization the spin-lattice relaxation time T1 of the monomer protons decreases very slowly while the flow viscosity of the sample increases greatly; this reveals that the motions responsible for the relaxation are mainly rotational. These motions can be considered to be thermally activated: the activation energies increase as the polymerization proceeds. The results we have obtained can be explained by assuming that there is a motion which has a predominant effect upon the relaxation and that a distribution of correlation frequencies, the width of which increases as the polymerization proceeds, is present. By making certain assumptions it has been possible to obtain some information about this distribution.