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Syntheses and properties of syndiotactic polystyrene
Author(s) -
Ishihara N.
Publication year - 1995
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19950890151
Subject(s) - polystyrene , tacticity , materials science , polymer science , polymer chemistry , chemical engineering , composite material , polymer , engineering , polymerization
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 and water/steam resistance. Since SPS has excellent dielectric properties, it is useful as a capacitor insulation material. 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. A system composed of a homogeneous titanium compound and methylaluminoxane (MAO) is an effective catalyst for syndiospecific polymerization of styrene. On the other hand heterogeneous titanium compounds containing halogen make a mixture of isotactic and syndiotactic components. The amount of syndiotactic polystyrene obtained is dependent on the mole ratio of Al to Ti. The result of ESR measurement suggests the Ti 3+ species are important as a highly active site for producing syndiotactic polystyrene. A comparison of the stereoregularities of polypropylene and polystyrene formed by various metallocene catalysts is studied. The (C 6 H 6 ) 2 C(η 5 ‐C 5 H 4 )(η 5 ‐C 9 H 6 )TiCl 2 /MAO system gives a homogeneous catalyst for the polymerization of propylene giving isotactic rich polypropylene and of styrene to give syndiotactic polystyrene.