AbstractMechanical properties, shear modulus, and damping of a series of polyacid divalent metal salts have been correlated with the degree of salt formation. The salts were preparedin situby molding mixed powders of 94/6 acrylic acid–2‐ethylhexyl acrylate and zinc oxide at temperatures of 200–300°C. and pressures of 5,000–10,000 psi. Zinc oxide consumption was followed by x‐ray techniques. Compositions contained 25–200 of theory metal oxide as charged. Excesses, over theory, of metal oxide were shown to lead to the formation of substantial amounts of pendent half‐salts which are high damping and have temperature‐sensitive shear moduli. Only complete reaction as the di‐salt, at 300°C. and 10,000 psi, leads to low damping products with temperature‐insensitive high modulus. The modulus increase due to ionic bonding as the di‐salt, over that expected from classical filler action alone, ranged from 40 to 80, depending upon the theory chosen to calculate filler action. The pendent half‐salt gives much smaller moduli increases and unreacted metal oxide appears to act as classical filler in an intertangled complex polyelectrolyte salt matrix. The modulus of the di‐salt was found to be 6–7 times higher than moduli for
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