Role of tacticity on the rheological and orientation behavior of metallocene-catalyzed semi-syndiotactic polypropylenes
Abstract
With metallocene-catalyst technology, it has become possible to synthesize polymers with well-controlled tacticity, thereby providing a wide range of polymers with the same monomer. However, the role of tacticity on the structure, mechanical, and flow behavior are poorly understood. We are studying custom-synthesized semi-syndiotactic polypropylenes with varying amounts of syndiotacticity using DSC, mechanical testing, rheology, and rheo-optical techniques. In contrast to what is seen in traditional isotactic polypropylenes, our DSC and rheological results indicate that these materials may possess a unique crystal morphology that melts at around 70°C. This unique `mesophase' plays a critical role in the mechanical and the orientation behavior. Using rheo-optical FTIR spectroscopy, we are currently studying the distinct contributions of the `mesophase' and the amorphous regions in these elastomeric materials. In the melt state, the entanglement behavior, and the flow birefringence depend significantly on the tacticity of the materials.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2001
- Bibcode:
- 2001APS..MARN17010M