Crosslinking of hydroxyl-terminated liquid rubber with divalent metal salts of mono(hydroxyethyl) phthalate,anhydrides, and bisepoxide

Crosslinking of hydroxyl-terminated liquid rubber with divalent metal salts of mono(hydroxyethyl) phthalate, anhydrides and bisepoxide was investigated by the diols-anhydridesbisepoxide, reactions. As the anhydride, succinic anhydride and hexahydrophthalic anhydride were used, and bisphenol A diglycidyl ether was the bisepoxide used. The metal carboxylate groups of these metal salts catalyzed the crosslinking reactions and, further, the Mg salt showed higher catalytic activities than the Ca salt. As for the physical properties of the metal-containing cured rubbers obtained, tensile strength and Shore A hardness increased with increase in the metal salt content. In addition, the rubbers containing Mg showed better physical properties than those containing Ca. Meanwhile, elongation showed a maximum with increase in the metal salt content. Resistance; to water and chemical attack, thermal behavior, and stress relaxation are also discussed.