Olefin polymerization polyolefin production

The growth of polyolefin fibers continues. Advances in olefin polymerization provide a wide range of polymer properties to the fiber producer. Inroads into new markets are being made through improvements in stabilization, and new and improved methods of extmsion and production, including multicomponent extmsion and spunbonded and meltblown nonwovens. 

Zirconium and hafnium hydrides can catalyze the olefin polymerization under olefin pressure and the polyolefin hydrogenolysis under hydrogen pressure.260 It is potentially interesting for plastic recovery and transformation into valuable products. 

The largest-volume polymers are polyolefins, and the kinetics of olefin polymerization are fairly similar to the ideal addition process just considered. All these olefins form condensation products to form a very long-chain alkane such as... 

A major objective of our research has been to introduce polar groups into polyolefin molecules. With the anionic type of catalysts, copolymerization is very difficult because most nonhydrocarbon vinylic monomers deactivate the catalyst system and stop olefinic polymerization. However, by the AFR route, the desired olefin is completely polymerized before polar monomers are introduced so that high yields of product are possible. 

The predominant product in each case was titanium trichloride (aka "tickle 3"), an active catalyst for olefin polymerization. The preferred cocatalyst was diethyl-aluminum chloride (DEAC). TiCl from eq 3.1 contains co-crystallized aluminum trichloride. TiCl from eq 3.3 may contain small amounts of complexed aluminum alkyl. Products from eq 3.1 and 3.2 were supplied commercially by companies such as Stauffer Chemical and Dart (both now defunct). Catalyst from eq 3.3 was manufactured on site by polyolefin producers, usually in an inert hydrocarbon such as hexane. 

One of the most remarkable aspect on the bis-Cp titanium derivative chemistry has been the production of new and unprecedented variety of polyolefins. The use of this type of complexes as Ziegler-Natta pre-catalyts for the olefin polymerization has opened new possibilities to produce polyolefins with different properties, and significant effort has been devoted to the design of new bis-Cp catalyst structures. This section summarizes simple aspects related to the polymerization of ct-olefins catalyzed by bis-Cp titanium complexes containing a cr-Ti-C bond. A more comprehensive review of the catalytic applications of titanium complexes in the a-olefin polymerization processes is covered in Chapter 4.09. 

Since the discovery of olefin polymerization using the Ziegler-Natta eatalyst, polyolefin has become one of the most important polymers produeed industrially. In particular, polyethylene, polypropylene and ethylene-propylene copolymers have been widely used as commercial products. High resolution solution NMR has become the most powerful analytieal method used to investigate the microstructures of these polymers. It is well known that the tacticity and comonomer sequence distribution are important factors for determining the mechanical properties of these copolymers. Furthermore, information on polymer microstructures from the analysis of solution NMR has added to an understanding of the mechanism of polymerization. 

Before the 1970s, Ziegler-Natta catalysts for a-olefin production were normally prepared from certain compounds of transition metals of Groups IV-VI of the periodic table (Ti, V, Cr, etc.) in combination with an organoraetallic alkyl or aryl (Table I). Practically all subhalides of transition metals have been claimed as catalysts in stereoregular polymerization. Only those elements with a first work function <4 eV and a first ionization potential <7 V yield sufficiently active halides, that is, titanium, vanadium, chromium, and zirconium (7, Only titanium chlorides have gained widespread acceptance in crystalline polyolefin production. 

Breakthroughs in single-site catalysis have completely transformed our view of alpha-olefin polymerization catalysis. The conventional Ziegler—Natta catalysts used in industrial production of polyolefins... 

We call this the "Reactor Granule" technology, and it represents a revolution in the development of "Ziegler-Natta" olefin polymerization. This "Reactor Granule" becomes a micropolyolefin production plant in which polyolefin alloys and blends are formed directly from the monomers. ... 

Kinetic investigations of olefin polymerization with Ziegler-Natta (ZN) catalysts provide information for understanding the mechanism of these reactions. Knowledge of kinetic regularities is also necessary for development of industrial productions of polyolefins. 

Hydrogen is the most used molecular weight regulator in polyolefin production. There are many publications describing the effect of hydrogen oti olefin polymerization. The dependence of catalyst activity on the presence of hydrogen varies with the nature of the monomer and catalyst. 

Over the last 60 years, only few discoveries have had such a visible impact on the development of our modern society than Ziegler-Natta olefin polymerization catalysts. They have facilitated large-scale production of synthetic polyolefins and rubbers and subsequently the introduction of cheap commodity materials in our everyday life. 

The discovery of a highly active family of catalysts based on iron, a metal that had no previous track record in this field, has highlighted the possibilities of further new catalyst discoveries. The search for new catalysts be restricted to metals that have a history of giving polymerization-active centers was no longer needed. The LTMs especially are likely to provide fertile ground for future development, and the greater functional group tolerance of the LTMs also offers the attractive prospect of polar co-monomer incorporation. A relatively small amount of functionality can dramatically transform the adhesion and wettability properties of polyolefins more heavily functionalized products offer the prospect of materials with totally new properties and performance parameters. It is clear that, for olefin polymerization catalysis, the process of catalyst discovery and development is far from over. 

The history and early developments in the pioneering work of polymers up to the most recent advancements are covered. Olefin polymerization started about 100 years back without involvement of metals, following anionic or radical pathways. The contemporary olefin polymerization industry depends mainly on the use of metal complexes as catalysts. At the present time, metal-catalyzed polymerization represents the most successful, conceivable, and sustainable procedure toward the synthesis of polyolefins. Nowadays, the list of metals includes several transition metals in the generation of catalysts. In doing their catalytic role, they foUow various mechanisms that lead to a wide range of polymeric products. 

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