Rheological behavior of polypropylene-polystyrene alloys

The technology involved in making olefinic alloys has been advanced so that these alloys can compete in several markets currently served by high cost engineering thermoplastics. Recent advances in alloying have allowed non-olefinic polymers to be blended or alloyed with non-olefinic polymers. Polystyrene is an example of a non-olefinic polymer that is used to enhance properties. The combination of mechanical properties and flow properties exhibited by polypropylene/polystyrene alloys are impressive. The flow behavior of these alloys is often much better than that of engineering thermoplastics due to the beneficial contributions from the olefinic base polymer.; In this study, a broad molecular weight distribution polypropylene was alloyed with polystyrene in order to improve the property profile and enhance the flow characteristics of the injection molding grade resin. The rheological behavior was characterized using an extrusion plastometer, a capillary rheometer, injection molding machines, and a mold filling simulation program. These rheological characterizations and property profile comparisons showed that olefinic alloys had flow properties and property profiles that were significantly improved when compared with standard grades of polypropylene.