Introduction of adhesion promoters essentially affects the mechanical characteristics of the sealant (see Tables 1 and 2) and is one of the way to control the physicomechanical characteristics and adhesion of polymer compositions to different substrates [16–18]. The changes in the mechanical characteristics upon the introduction of adhesion promoters depend on the functionality of the latter via methoxy groups. When promoters with dimethoxy groups were used, reduc tion of modulus values and increase of relative elonga tion were noted. In the case of application of promot ers with trimethoxy groups, the modulus value, in con trast, increases and the relative elongation diminishes. This can be explained by the change of the structure of a curing network upon introduction of adhesion pro moters that can react with methoxy groups of the oli gomer and enter the main network. Therewith, it is possible that promoters with trimethoxy groups make the network somewhat denser and those with dimethoxy groups, in contrast, make it somewhat less branched.