Abstract
For the first time, ultra-high molecular weight polyethylene (UHMWPE) was produced in gas phase process with a new fluidized bed concept where the solids are dispersed phase and the gas is bulk phase as opposed to conventional fluidized bed reactors (FBRs). With this concept, UHMWPE with average molecular weights about 1-6,9 × 106 g mole-1 were produced with a commercial supported Ziegler-Natta catalyst by using a gas phase mini semibatch reactor system. Additionally, optimum conditions of gas phase polymerization for the best results of productivity, catalyst activity, molecular weight and crystallinity were determined by Taguchi experimental design and catalyst stability at the optimum condition was tested by video microscopy polymerization. The characterization of products was carried out experimentally by TGA, DSC, FTIR, and NMR.
Highlights
high density polyethylene (HDPE) can be produced both by fluidized bed and slurry technologies, currently ultra-high molecular weight polyethylene (UHMWPE) is produced by only slurry process
HDPE can be produced both by fluidized bed and slurry technologies, currently UHMWPE is produced by only slurry process
The added liquid phase contributes to a gas-liquid mass transfer limitation which can cause a reduction in reaction conversion [2] and the separation of the solvent from the polymer is rather expensive in terms of both construction and operation [3]
Summary
HDPE can be produced both by fluidized bed and slurry technologies, currently UHMWPE is produced by only slurry process. In order to achieve efficient heat and mass transfer rates, without having hot spots, we suggest to distribute the solids in the gas that is the solids are the dispersed phase and the gas is the bulk phase. In this configuration, the bubbles do not exist and do not cause any complexity in the hydrodynamics, and the gas phase is turbulent enough to have a homogenous, well mixed phase, i.e., the particles move together with the gas no matter what their sizes are, thereby to have only emulsion phase inside the reactor. New approach in fluidized bed technology was applied to realize gas phase production of this unique polymer
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