Patent ID: 8912296

Claim:
A process for preparing polystyrene having a weight average molecular weight (Mw) in the range of 120,000-160,000, a polydispersity in the range of 4-6 and a melt flow rate of a least 40 g/10 minutes by feeding styrene into a reaction system through which the styrene passes as a component of a reaction mixture as it is polymerized, the reaction system including an initial reaction zone and a downstream reaction zone, comprising the steps of: polymerizing styrene in the initial reaction zone to form polystyrene having a Mw of greater than 300,000 and a polydispersity in the range of 1.5- to 2.5, 10- to 30 wt. % of the styrene fed to the initial reaction zone being polymerized there; and polymerizing styrene remaining in the reaction mixture in the downstream reaction zone, a chain transfer agent being mixed with the reaction mixture at the commencement of the downstream reaction zone.