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Formation of uniform polymer assembly with silica nano‐sol‐supported metallocene catalysts in a stirred‐tank reactor
Author(s) -
Li KuoTseng,
Yang ChengNi
Publication year - 2021
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.25662
Subject(s) - materials science , catalysis , polypropylene , polymer , polymerization , chemical engineering , metallocene , zirconium , toluene , nanoreactor , sol gel , polyethylene , nano , polymer chemistry , nanoparticle , composite material , organic chemistry , nanotechnology , chemistry , metallurgy , engineering
Silica nano‐sol is the precursor (before gelation and drying) of silica gel and has much greater surface area than gel. In this study, a spherical commercial silica nano‐sol in toluene with a dimension of less than 50 nm was successfully used to support two bridged metallocenes (dicholo ‐ dimethyl silybis(indenyl) zirconium (IV) and dichloro – ethylenebis(indenyl) zirconium (IV),denoted by ZrSi and ZrEt, respectively). These sol‐supported catalysts showed significantly better propylene polymerization activities than gel‐supported catalyst reported earlier. The influences of solution co‐catalyst ([Al 4 O 3 Me 6 ] n, n = 5–7, abbreviated as MAO) content and reaction time on polymerization were investigated. The increase of co‐catalyst concentration increased activity, polymer length, and melting temperature. Polymer assemblies produced with ZrSi/Sol changed from diamond‐shape to rod‐like shape as time proceeded. Uniform dumbbell – shaped micro‐sized polypropylene assemblies were obtained with catalyst ZrEt/Sol. The results were explained in terms of the penetration theory proposed before for multiphase mass transfer.