ISSN:
1042-7147
Keywords:
Polyolefin
;
Polypropylene
;
Polyethylene
;
Catalyst
;
Polymerization
;
Process
;
Elastomer
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The polyolefins, especially polypropylene and polyethylene, industry of today is very different from that of 10 years ago. The development of highly active and stereospecific catalysts, represented by Ti/Mg supported catalysts, have made the gas-phase polymerization process practical.The trend in catalyst development is shifting from an emphasis on improving the stereospecificity and activity toward improving the polymer physical properties, processability and morphology.Many hybrid thermoplastic olefins, such as high-impact copolymers, propylene-ethylene-butene terpolymers, and very low density polyethylene, have already been developed by utilizing the features of the gas-phase polymerization process.These hybrid thermoplastic olefins cover a very broad range of products. They cannot be clearly identified as polyethylenes, polypropylenes or elastomers.Incidentally, metallocene catalysts for polyolefins have been under development for the past 15 years, and are now in the early stage of commercialization. These catalysts differ significantly from the conventional heterogeneous catalysts.They can polymerize not only ethylene, propylene and other linear α-olefins, but also styrene, cycloolefins and functional monomers In addition, they can control the microstructure of polymer molecules by varying the transition metals and the cyclopentadienyl ligands.Because of these features, we have to be confident that the development of metallocene catalysts, or more widely homogeneous catalysts, may be a dominant force throughout the 1990s in the polyolefin industries.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pat.1993.220040702
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