ABSTRACT
Comonomers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 12.7 Examples of Ethylene/Propylene Copolymers from Single-Site Catalysts . . . . . . . . . . . . . . . 327 12.8 Crystallinity of Ethylene/Propylene Copolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 12.9 Influence of Regio-and Stereoregularity of Propylene Insertion on Crystallization
Behavior and Elasticity of Ethylene/Propylene Copolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 12.10 Molecular Picture of Elasticity: Diene-and Ethylene-Based Elastomers . . . . . . . . . . . . . . . . . 332 12.11 Ethylene/Propylene Copolymers: Elasticity in the Uncured State. . . . . . . . . . . . . . . . . . . . . . . . . 334 12.12 Elastomers Based on Ethylene: Selection of Catalytic Systems for Their Production . . . 336 12.13 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 References and Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
DK3712: “dk3712_c012” — 2007/10/10 — 14:11 — page 314 — #2
Following the discovery of the stereoselective polymerization of vinyl monomers,1-4 the relevance of tacticity in the placement of monomeric units along the macromolecular chain was immediately recognized.2,3 In fact, the average length of tactic sequences of monomeric units in the polymer chain is the main factor determining the occurrence and the degree of crystallinity of polymeric materials, and hence, their physical properties. It is also well-recognized that tacticity can also be relevant for copolymers. This is not only true for the obvious case of block copolymers, but also for random copolymers when the formation of crystallizable sequences requires a tactic placement of monomeric units, for instance for propylene-rich4 or 1-butene-rich5 random copolymers with a minor amount of ethylene.
