HIGHLY VISCOUS SILICONE MASSES COMPRISING ALKENYL-TERMINATED POLYDIORGANOSILOXANES WHICH MAY BE CROSS-LINKED BY ADDITION

Addition crosslinkable organopolysiloxane compositions which cure to organopolysiloxane elastomers of high elongation at break and high tear resistance contain a high viscosity, alkenyl-terminated, and substantially pendant alkenyl group-free organopolysiloxane, an organopolysiloxane having pendant alkenyl groups and optionally alkenyl-terminal groups, an Si-H functional crosslinker, and a hydrosilylation catalyst.