Head to head polymers. XVII: Head to head polypropylene |
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Authors: | Steven Grossman Andrzej Stolarczyk Otto Vogl |
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Affiliation: | (1) Polymer Science and Engineering Department, University of Massachusetts, 01003 Amherst, MA, USA;(2) Present address: The Upjohn Company, 410 Sackett Point Road, 06473 North Haven, CT, USA |
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Abstract: | Head to head polypropylene was prepared by catalytic hydrogenation of eithercis-1,4-poly(2,3-dimethylbutadiene) ortrans-1,4-poly(2,3-dimethylbutadiene) with cobalt 2-ethylhexanoate/triethylaluminium as the hydrogenation catalyst in decahydronaphthalene solution. The hydrogenation occurred predominantly bycis hydrogen addition, but was not stereospecific. The samples of head to head polypropylene were characterized by IR and NMR, particularly by13C-NMR spectroscopy. The polymers were amorphous and exhibited glass transition temperatures about 20°C lower than that of head to tail poly-propylene; the glass transition temperatures were measured by DSC and varied somewhat from sample to sample (sufficiently high molecular weight) according to their stereochemistry. TheTgvalues were confirmed by Rheovibron measurements. The thermal stability of head to head polypropylene is not significantly different from that of either atactic or isotactic head to tail polypropylene.Part XVI:Grossman S., Yamada A., Vogl O., J. Macromol. Sci.-Chem.A 16, 897 (1981). |
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Keywords: | Catalytic hydrogenation Coordination polymerization Glass transition temperature 1,4-Poly(2,3-dimethylbutadiene), cis- and trans- Polymers |
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