Ethylene/propylene copolymerization

Fig. 10. Copolymerization diagrams for ethylene/propylene copolymerization carried out with (Me2C(3-tert-BuCp)(Flu))ZrCl2 at 30 ( ) and 60°C ( ). (120).

Fig. 12. Rate constant kp of the ethylene/propylene copolymerization as a function of the ethylene concentration in the liquid phase at 37° C dashed line, calculated solid line, measured (114).

In order to overcome thfe drawbadr, new types of multi-unsaturated hydrocarbon monomers have been synthedzed in recent years and their behavior in ethylene-propylene copolymerization has been extensively studied. Such mcmomers are characterized by the presence of one unconjugated double bond suitable for copolymerization and of a system of two or three cmijugated double bonds, the high reactivity of which makes them competitive with conventional diene rubbers in sulfur vulcanization despite their low concentration. 

Table 3. Reactivity ratios reported for ethylene-propylene copolymerization (16)...

Vizen,Ye.V., Kissin, Yu.V. Composition distribution for copolymers in ethylene-propylene copolymerization with the heterogeneous catalyst system VC13-A1(C2H6)3. Vysokomol. Soyed. A, 11, 1774-1782 (1969). - Polymer Sci. USSR A, 11,2017-2028 (1969). 

Fig. 30 Ethylene/propylene copolymerization (gas feed ratio 0.25) with the Ziegler-catalyst system TiCLi/AfEts/extemal donor supported on MgCl2 (0.2 MPa, 50°C) video microscopic snap-shots and kinetic evaluation of six particles...

Ogawa, T. Inaba, T. Gel permeation chromatography of ethylene-propylene copolymerization products. J. Appl. Polym. Sci. 1988, 21, 2979. 

Table 2. Reactivity Ratios for Ethylene/Propylene Copolymerization by Various Metallocenes...

The issues raised in Section 7.2 are best illustrated by considering several real-world examples. Isotactic polymerization is considered first, followed by syndiotactic polymerization. These classic examples are followed by two studies on novel polymerization systems. The third case study concerns a single-site metallocene system that produces a stereoblocky material with novel elastomeric properties. The last example involves an ethylene-propylene copolymerization catalyst that exhibits nonrandom monomer incorporation. Common themes of these four examples include monomer-polymer chain control, van der Waals attraction, and the importance of the counteranion. 

Ethylene/propylene copolymerization is of significant commercial importance. Elastomers formed from random ethylene/propylene copolymers (EP) possess a number of valuable properties including a high plateau modulus ( 1.6 MPa), which permits a higher filler loading and more cost-effective compounding. Furthermore, of the major hydrocarbon-based rubbers, EP is by far the least reactive with oxygen and ozone. 

FIGURE 7.23 Experimental (Exp.) and computed (Current) triad distributions for ethylene/propylene copolymerization with 8 show good agreement. 

FIGURE 7.24 Ethylene/propylene copolymerization insertion transition states of 8 for (a) ethylene insertion into an ethylene-terminated chain (ee) (b) propylene insertion into an ethylene-terminated chain (pe) (c) ethylene inserting into a propylene-terminated chain (ep) and (d) propylene insertion into a propylene-terminated chain (pp). The steric impact of a propylene methyl substituent on the geometry of the ep ethylene insertion transition state in (c) is shown in (e). The C-C distance of 2.64 A is indicative of substantial steric repulsion. 

Polyakov, O. G Rappe, A. K. Alternating ethylene/propylene copolymerization RFF molecnlar mechanics force field prognosticates effective zirconocene catalysts. Book of Abstracts, 218th National Meeting of the American Chemical Society, New Orleans, LA, Aug 22-26,1999 American Chemical Society Washington, DC, 1999 INOR-153. Chem. Abstr. 1999,1999, 541786. 

SCHEME 12.1 The five comonomer insertion events in ethylene/propylene copolymerization (M = metal center P = growing polymer chain). 

FIGURE 12.6 Definition of the reactivity ratios rj and r2 for ethylene/propylene copolymerization (E = ethylene = monomer 1 P = propylene = monomer 2 R = rate of indicated insertion process). 

Nature of Catalytic Sites and Distribution of Copolymer Molecular Properties for Common Ethylene/Propylene Copolymerization Systems... 

Type of Catalyst Systems and Reactivity Ratios in Ethylene/ Propylene Copolymerization (Monomer 1 = Ethylene Monomer 2 = Propylene)... 

Kinetics of Ethylene-Propylene Copolymerization over MgCl2-Supported Catalysts... 

A Study on the Active Sites of a Primary Type of MgCl2-Supported Catalyst by Ethylene-Propylene Copolymerization... 

Ethylene-propylene copolymerization was conducted using a primary... 

Ethylene-propylene copolymerization was conducted in a 2L stainless steel autoclave at 60 C for 15 minutes under a constant pressure of 1 atm with 8.5mmol of A1(C2Hb)3. the prescribed amount of catalyst (catalyst weight 2.0 3.0g, Al/Ti mole ratio 30 40) and IL of heptane. 

Ethylene - propylene copolymerization was used instead of propylene homopolymerization because of the clarity of the C-NMR spectrum. 

Taking previous results into consideration, it is possible that active sites for ethylene-propylene copolymerization is produced by grinding TiCU EB complex with HgCh. 

From all the results above, we may arrive at the conclusion that Active sites for ethylene-propylene copolymerization were produced by the decomposition of TiCU EB complex in the cogrinding process with MgCla. 

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