CR non-catalyzed crosslinking yield and mechanical properties of CR vulcanizates were studied in relation to aminosilane (N-2-aminoethyl-3-aminopropyltrimethoxysilane, DAS; 3-[2-(aminoethyl-amino)-ethylamino]propyltrimethoxysilane, TAS; or (3-aminopropyl)-tris-[2-(2-methoxyethoxy)-ethoxy]silane, MAS) concentration and functional group content. DAS gave the max. yield. As DAS concentration was raised, the percentage of specific nodes rose; and the 100% and 300% modules rose. With MAS and TAS, tensile strengths were lower and the tendency to physical relaxation at room temp. was lower. The DAS-crosslinked vulcanizates were more conducive to phys. relaxation at room temp. than were the TAS- or MAS-crosslinked vulcanizates.