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Polymer swelling

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Polyolefins are industrially produced in the gas dispersion and liquid dispersion reactors in the form of porous particles growing from supported catalyst particles. Monomers and other components sorb into the amorphous phase of semi crystalline polymer and diffuse through the porous polymer particle to the catalyst surface where they react. The unreacted monomer and impurities must be removed from the polymer product in the downstream processing. The knowledge of the solubility and transport properties of components of polymers is important not only in polymer production processes but also in the degassing and subsequent processing of polymer products. Observation of the polymer swelling during the sorption of penetrants is important for buoyancy correction of swollen volume in gravimetric data. For example, the effect of the swollen volume during ethylene sorption on sorption isotherms is about 20%.

During our swelling experiments, particularly during 1 hexene sorption, we observed also the “irreversible swelling”. During this phenomenon, the molecules of 1 hexene loosen the elastically constrained chains (Fig. 1) and thus the de swelling of particle is not going to provide original particle diameter but a larger one (Fig. 2). Therefore also the sorption of ethylene in PE loosened by previous sorption of 1 hexene is supposed to be higher than in untreated PE.

 

Contact

Juraj Kosek
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+420 220 443 296

University of Chemistry and Technology Prague
Department of Chemical Engineering
Technicka 5
166 28 Prague 6
Czech Republic

University of West Bohemia
New Technologies Research Centre (NTC)
Univerzitní 8
306 14 Pilsen
Czech Republic