The Absorption of Ultrasonic Waves in Benzene Solutions of Methyl Metacrylate in Different Polymerization Stages

Abstract

Measurements of ultrasonic absorption are performed by a pulse method in benzene solutions of nine sorts of methyl metacrylate specimens of different intermediate polymerization stages, including the monomers and the final product of polymerization. In the case of the monomer, the absorption decreases rapidly with concentration. Solutions of the polymers without unreacted monomers show a similar absorption coefficient to that of benzene itself, in spite of the remarkably high viscosity. For the intermediate products the fraction of polymers is estimated from the absorption coefficient, assuming that only the unreacted monomers have influence on the absorption. For the solutions of the specimens in which the fraction of polymers is fairly large, the above assumption requires some modifications. In this case some parts of unreacted monomer molecules seem to be enclosed in the network structures of polymers and deprived of their influence upon the absorption.