Polyethene production developments

The breakthrough in metallocene catalyst development occurred in the early 1980s when a metallocene catalyst, instead of an aluminium alkyl, was combined with methylaluminoxane (MAO) [8, 9, 10]. This catalyst system boosted the activity of metallocene-based catalyst and produced uniform polyethene with the narrow molar mass distribution typical for single-site catalysts. Efforts to polymerise propene failed, however the product was found to be fully atactic, indicating complete lack of stereospecificity of the catalyst [10]. 

Pellets (e.g. polyethene), granules (e.g. fertilizer) and coarser particulate materials (explosives, media from granular filters), often contain a small dust (sub 50-100 pm) friction, which is undesired. In many cases, customers require the levels of such dust or fibers to be reduced to levels well below 0.5% (in the case of polyethene pellets the level desired is 50 ppm ). While the methods of production and handling can be optimised to prevent the production of such dust, this approach is not always feasible. A number of devices have thus been developed for removing what one may call "fugitive" dust from such products. Some of these are shown in Figure 1. 

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