Transparent high impact alloy

An improved tough, transparent polymer alloy comprised of 90 to 20 weight percent of a brittle polymer with a weight average molecular weight greater than 180,000; 0 to 60 weight percent of a rubbery polymer; 0 to 80 weight percent of a ductile polymer; and between greater than 0.4, i.e. between 0.5 and 3 weight percent of a plasticizer, i.e. mineral oil which resides in the brittle polymer. The brittle polymer can have molecular weights between 220,000 and 300,000, and may be as high as 400,000. In one of the preferred embodiments the brittle polymer is a copolymer of styrene and methyl methacrylate which copolymer ranges between 50 and 55 weight percent, the rubbery polymer is 0 weight percent, the ductile polymer is a styrene butadiene block copolymer ranging between 45 and 50 weight percent, and the mineral oil is 1.5 weight percent. Notched IZOD impact strength ranges between 1.0 to 6.0 ft-lb./in., preferably between 2.0 and 4.5 ft-lb./in. The haze can be less than 1.5% or it can be between 1 and 4%.