Spring 2008 Chap 12 ZieglarNatta Catalyst Before ZN

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(>106) is synthesized LDPE = HPPE HDPE This has less hardness, stiffness and strength compared to HDPE, but better ductility, Free radical Use chromium compounds. Zieglar-Natta process is recent application. A few number of branches Al. R 3, Al. HR 2 10 billion lb/yr PP Natta 4 billion lb/yr l. Characteristic conditions for PP PP and solid catalysts are put together at 50℃ to 90℃ below 5 atm. 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, H 2 O, … Hanyang Univ.

Spring 2008 Dr. Ziegler and Dr. Natta Both earned the Nobel Prize in 1963 !! Hanyang Univ.

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

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

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

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

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