IONOMERS BASED ON CARBOXYL-CONTAINING POL Y(DIMETHYLCARBOSILOXANE)

The rheological and mechanical properties of siloxane ionomers were st udied on the samples synthesized by interaction of zinc and nickel ace tates with poly(dimethylcarbosiloxanes), having M = (2.06.6.5) x x 10( 4)) and containing 0.8-3.0 mol % of randomly arranged side carboxyl gr oups. It was found that associates of ionomer macromolecules exhibited an unusually slow decay kinetics in dilute solutions. The viscosity o f ionomers in the block grows by several orders of magnitude with incr easing metal content. The viscosity of ionomers increases with the she ar stress not only in solutions (as in carbochain ionomers), but in th e block as well. Heat treatment of the ionomers leads to the formation of three- dimensional cross-linked structures of two types: the rever sible physical networks at 120-140 degrees C, or the irreversible netw orks with chemical cross-links at 160-180 degrees C. Mechanical proper ties of the ionomers are significantly affected by the temperature of preliminary heat treatment. The character of bonds, forming the cross- links of networks of various types, is discussed.