ON THE EVOLUTION OF RELAXATION PROCESSES DURING THE FORMATION OF A MACROMOLECULE

The dielectric relaxation spectra of a liquid undergoing chemical reac tions to produce a macromolecule have been measured at different insta nts of reaction and in the GHz frequency range. As the reaction procee ds, a second and slower relaxation process separates out from a faster relaxation process. The rate of the faster process changes little but its strength decreases with increase in the molecular weight of the m acromolecule. Quantitative information on these changes show that the negative feedback between chemical reactions and molecular diffusion, which is irreversible in nature, has the same consequences for the rel axation behaviour as supercooling of a molecular or polymeric liquid. This implies that for each macromolecular state characterized by its m olecular weight, there is a corresponding state of its unreacted compo nents at low temperatures with similar thermodynamic and kinetic prope rties. Under certain condition, the extent of chemical reaction can be determined from dielectric measurements at a single GHz frequency.