Polymerization screening reactor

Figure 3.51 96-well reactor array for the parameter screening of polymerization conditions [82] (by courtesy of ACS). 

Chemical activities in the field of mass screening are often related to combinatorial chemistry [51,52]. One major goal, especially in the field of solid phase chemistry involving polymers like DNA or peptides, aims at the increase in the number of compounds per reactor volume and time. Commercially available microtiter plates are established as reactors in this case whereby robotic feed systems fit perfectly to their dimensions. A drastic reduction of reaction volume and increase in number of reaction vessels ( wells ) leads to the so-called nanotiter plates (e.g. with 3456 wells). Microfabrication methods such as the LIGA process are ideal means for the cost effective fabrication of nano-titer plates in polymeric materials by embossing or injection molding techniques so that inexpensive one-way tools are realized. 

DOW in Midland, USA, performed metallocene-catalyzed polymerization of ethylene using a homebuilt tube reactor setup with advanced microflow tailored plant peripherals for heating, temperature monitoring, pressure control and dosing via smart valves and injectors. Screening of process conditions was a driver [19]. Also, flexibility with regard to temperature and pressure at low sample consumption was an issue. Quality of the information is another motivation due to the advanced process control and sensing. 

In the following sections, the performance of the imine complexes is discussed. It must be noted [Ila] that comparing catalyst activity data from different studies is only approximate due to their dependence on experimental conditions, that is reactor geometry, stirring procedure, polymerization time, pressure and the like. Therefore it is advantageous to include known complexes for a direct comparison ( benchmarking ) under identical experimental polymerization conditions. It follows that the catalytic activity and productivity obtained for these known catalysts may differ from the ones reported in the literature they are characteristic of the equipment and screening procedure used. 

Slurry" from more than one reactor is "dropped" into a "stripper" to remove unreacted monomer and then transferred to a large "blend tank." The suspended polymer particle can easily be separated from the water phase by filtering or centrifuging. The "wet cake" is then sent to a rotary kiln type dryer and bagged. The particle size of polymers obtained in this manner are usually much larger than those obtained with emulsion polymerization. They can be defined by a conventional screen analysis with respect to particle size. 

Table IX. CATALYST SCREENING (Fischer Tropsch Reactor) Ethylene Polymerization...

Experimental equipment that is useful for the rapid screening of catalysts in support of the global polyethylene business must meet two critical requirements (1) The polymerization reactor needs to be properly designed so that an experiment can be carried out imder steady-state polymerization conditions for a minimum of about 20 minutes in order to provide important catalyst activity data and sufficient polymer for complete characterization. (2) A process model is needed in order to quantitatively determine important kinetic parameters of an experimental catalyst. 

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