ABSTRACT
About one-half of all synthetic resin produced worldwide is polyolen.1 The two principal compositions are polyethylene (mainly its high density and linear, low-density forms) and polypropylene (mainly its isotactic form). The widespread and enduring commercial success of olens derives from a combination of favorable properties: they are inexpensive,
CONTENTS
5.1 Introduction ........................................................................................................................ 129 5.1.1 The Evolution of Polyolens: From Commodities to Specialties .................... 129 5.1.2 “Homogeneous” Polyolen-Clay Composites by Polymerization Filling ..... 131 5.1.3 Toward Polyolen-Clay Nanocomposites by In Situ Polymerization ............ 134 5.1.4 Scope and Goals of This Chapter ........................................................................ 139
5.2 Homopolymerization of α-Olens .................................................................................. 139 5.2.1 Homopolymerization of Ethylene ....................................................................... 139
5.2.1.1 Phillips’ Catalysts for Ethylene Polymerization ................................. 139 5.2.1.2 Ziegler-Natta Catalysts for Ethylene Polymerization ....................... 140 5.2.1.3 Metallocene Catalysts for Ethylene Polymerization .......................... 147 5.2.1.4 Early Transition Metal-Based Post-Metallocene Catalysts ............... 155 5.2.1.5 Late Transition Metal-Based Post-Metallocene Catalysts ................. 156
5.2.2 Homopolymerization of Propylene ..................................................................... 164 5.2.2.1 Ziegler-Natta Catalysts for Propylene Polymerization ..................... 164 5.2.2.2 Metallocene Catalysts for Propylene Polymerization ........................ 168
5.3 Copolymerization .............................................................................................................. 170 5.3.1 Ethylene/α-Olen Copolymerization ................................................................. 170
5.3.1.1 By Comonomer Addition ....................................................................... 170 5.3.1.2 By Tandem Concurrent Catalysis ......................................................... 172
5.3.2 Ethylene/Polar Monomer Copolymerization .................................................... 174 5.3.3 Propylene-Comonomer Copolymerization ....................................................... 175
5.4 Future Research Directions .............................................................................................. 175 Acknowledgments ...................................................................................................................... 176 References ..................................................................................................................................... 176
highly processible, durable, and biocompatible. Polyolens have even been described as “green polymers,” based on their low density and high recyclability, as well as their chemical simplicity (halogen-free).1
