1. Hanyang Univ. Spring 2008 Chap 12. Zieglar-Natta Catalyst - Before Z-N Catalyst invention, PP composites were only atactic form - After that, isotactic PP composites of extraordinary MW(>10 6 ) is synthesized LDPE = HPPEHDPEPP This has less hardness, stiffness and strength compared to HDPE, but better ductility, Free radical 10 billion lb/yr Use chromium compounds. Zieglar-Natta process is recent application. A few number of branches AlR 3, AlHR 2 Natta 4 billion lb/yr Characteristic conditions for PP PP and solid catalysts are put together at 50 ℃ to 90 ℃ below 5atm. After stopping of reaction, it is washed with H 2 O or ROH to remove the catalysts. MW is on the control of chain transfer agent E.g.) CO 2, O 2, H 2, H 2 O, … Zieglar-Natta Catalyst

2. Hanyang Univ. Spring 2008 Dr. Ziegler and Dr. Natta

3. Hanyang Univ. Spring 2008 Assumption: equal site reactivity - Monometallic Corsee mechanism Monometallic Bimetallic mechanism Zieglar-Natta Catalyst

4. Hanyang Univ. Spring 2008 β-TiCl 3 1 vacancy site => isotactic 2 vacancy sites => atactic 1 vacancy site => isotactic Bimetallic TiCl Zieglar-Natta Catalyst α-TiCl 3

5. Hanyang Univ. Spring 2008 Zieglar-Natta Catalyst This image shows the mechanism by which the Ziegler Natta catalyst polymerizes 1-propene. The image was created by Christine Ann.

6. Hanyang Univ. Spring 2008 Polymerization rate Time Types of rate curves observed in Ziegler-Natta polymerization: (A) constant; (B) decaying; and (C) decaying to constant A B C

7. Hanyang Univ. Spring 2008 Polyethylene Polymerization A B C D E

8. Hanyang Univ. Spring 2008 Chap 13. Polymerization Processes  Homogeneous polymerization  Heterogeneous polymerization Bulk polymerization Solution Polymerization Suspension polymerization Emulsion polymerization

9. Hanyang Univ. Spring 2008 Bulk polymerization

10. Hanyang Univ. Spring 2008 Solution Polymerization

11. Hanyang Univ. Spring 2008 Suspension polymerization

12. Hanyang Univ. Spring 2008 Emulsion polymerization

13. Hanyang Univ. Spring 2008 Stages in Emulsion Polymerization