AMSD α-Methyl styrene dimer AMSD is a molecular weight modifier for SB latex, styrene series resins, etc. It is a mixture of two different compounds. PROPERTIES Name Product Identity % Benzene, 1,1'-(1,1-dimethyl-3-methylene-1,3-propanediyl)bis- (CAS No) 6362-80-7 60 - 100 Benzene, 1,1'-(1,3,3-trimethyl-1-propene-1,3-diyl)bis- (CAS No) 6258-73-7 5 - 10