Abstract Homogeneous titanium compound and methylaluminoxane (MAO) system is an effective catalyst for syndiospecific polymerization of styrene. A comparison of the stereoregularities of the polypropylene and the polystyrene formed by various metallocene catalysts is studied. (C6H6)2C(η-C5H4)(η-C9H6)TiCl2 / MAO system give homogeneous catalyst, for the polymerization of propylene giving isotactic rich polypropylene and of styrene to give syndiotactic polystyrene. Heterogeneous titanium compound containing halogen makes a mixture of isotactic and syndiotactic components. The amount of syndiotactic polystyrene obtained is dependent on the molar ratio of Al to Ti. The result of ESR measurement suggests that Ti3+ species are important as a highly active site for producing syndiotactic polystyrene (SPS). Syndiotactic polystyrene (SPS) is a new crystalline engineering thermoplastic. With a melting point of 270 °C and its crystalline nature, SPS has high heat resistance, excellent chemical resistance, water/steam resistance. The rate of crystallization is very fast in comparison with isotactic polystyrene (IPS), thus, SPS can be used in a number of forming operations, including injection molding, extrusion and thermoforming.
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