Abstract <p>The influence of various additives on the adhesive characteristics of compositions based on nitrile–butadiene rubber (NBR) and thiokol mixtures was studied. Indene-coumarone resin, pine rosin, highly chlorinated polyethylene resin, oil-polymer resin, product “Pavolan,” the copolymer of maleic anhydride with α-olefins C₁₂–C₁₄, and a low-molecular-weight polymer (LMWP-1), a complex of isoprene oligomers, were used as additives. It was shown that the best adhesive properties are exhibited by the compositions based on the nitrile–butadiene rubber and thiokol containing 5 parts of weight of rosin. The adhesive strength of the compositions containing rosin increases many times relative to that of the control sample. It was found that the adhesive strength of the compositions based on the NBR–thiokol mixture does not depend on the substrate type and testing method, which is typical for “pressure-sensitive” adhesives. It was demonstrated that in these compositions the used modifiers act not as adhesive additives influencing the intensity of interfacial interaction between an adhesive and a substrate but in a different way, affecting factors determining the performance of pressure-sensitive adhesives.</p>