Abstract: A monomer stream containing propylene is supplied to a polymerization reactor which is operated under temperature and pressure conditions effective for the production of a stereoregular propylene polymer fluff. A titanium-based supported Ziegler-Natta catalyst having a titanium content of at least 1.7 wt. % and incorporating an internal electron donor is incorporated into the monomer stream. A trialkylaluminum co-catalyst is supplied to the monomer stream in an amount to provide an aluminum/titanium molar ratio within the range of 50-500. A silicon-based external electron donor is also supplied to the monomer stream in an amount to provide an aluminum/silicon molar ratio within the range of 10-500. Polymer fluff recovered from the polymerization reactor has a melt flow rate of at least 200 grams/10 minutes, and a xylene soluble content of no more than 4 wt. %.

Abstract: It has been discovered that improved polystyrene products may be obtained by polymerizing styrene in the presence of p-t-butyl styrene (TBS) and optionally at least one di-olefinic substituted aromatic compound, such as isopropenyl styrene, sec-butenyl styrene, m-isobutenyl styrene, p-diisopropenyl benzene, diallyl benzene, and/or diallyl phthalate. The resulting copolymers have a higher glass transition temperature (Tg), a higher molecular weight distribution (MWD), a higher Mz, and a lower melt flow index (MFI) as compared with a polymerized product made by an otherwise identical method except that TBS and/or the di-olefinic substituted aromatic compound are not used. These copolymers are also more highly branched as compared with a polymerized product made by an otherwise identical method in the absence of TBS and/or a di-olefinic substituted aromatic compound.

Abstract: It has been discovered that improved polystyrene products, such as high impact polystyrene (HIPS), may be obtained by polymerizing styrene with a diene polymer in the presence of at least one multifunctional initiator. The presence of the multifunctional initiator tends to cause more branched structures in the polystyrene. Unexpectedly, the ratio of % gel to % rubber (G/R or rubber phase volume) increases as the swell index increases which is the opposite of the conventional trend. Additionally, acceptable G/R values can be achieved at increased polymerization rates with these initiators.

Abstract: Disclosed is a composition comprising an impact modified polystyrene prepared using a process comprising dissolving a styrene-butadiene-styrene block copolymer in styrene monomer and polymerizing the styrene monomer wherein the impact modified polystyrene has a haze value of less than or equal to 12 percent. Also disclosed is an impact modified polystyrene prepared using the same process and having a ratio of Mz/Mn of at least 4.1.