Thermoplastic resin composition

A thermoplastic resin composition comprising:

• (A) about 10% to about 99% by weight of a thermoplastic resin comprising a rubber-modified acrylic graft copolymer, and (B) about 1% to about 90% by weight of a branched aromatic vinyl copolymer resin comprising a silicon compound, wherein the branched aromatic vinyl copolymer resin (B) comprises a copolymer or a mixture of copolymers formed of (b1) about 10% to about 85% by weight of an aromatic vinyl monomer, (b2) about 10% to about 85% by weight of an unsaturated nitrile monomer, (b3) about 1% to about 50% by weight of a (meth)acrylate monomer, and (b4) about 0.1% to about 20% by weight of a silicon compound having two or more unsaturated groups, wherein the silicon compound (b4) has a vinyl content of about 0.05 to about 10 mmol/g and a viscosity of about 5,000 cPs or less.