additional acrylonitrile monomer and additional crosslinking agent is added to the seed polymer containing latex as a general rule from about 4 parts by weight to about 30 parts by weight of styrene from about 1 part by weight to about 20 parts by weight of additional acrylonitrile and from about 0 01 to 2 parts by weight of the crosslinking agent will be added in this second stage of the polymerization it is preferred to add from about 6 parts by weight to about 22 parts by weight of styrene from about 3 parts by weight to about 12 parts by weight of acrylonitrile and from about 0 05 parts by weight to 1 part by weight of the crosslinking agent it is typically more preferred for from about 10 parts by weight to about 17 parts by weight of styrene from about 4 parts by weight to about 8 parts by weight of acrylonitrile and from about 0 1 parts by weight to about 0 5 parts by weight of the crosslinking agent to be added to the seed polymer latex to initiate the second phase of the polymerization a wide variety of crosslinking agents can be utilized in carrying out the polymerizations used in the synthesis of the rubbery polymer some representative examples of crosslinking agents which can be utilized include difunctional acrylates difunctional methacrylates trifunctional acrylates trifunctional methacrylates and divinylbenzene a crosslinking agent that has.