Artículos de revistas
Silica/clay organo-heterostructures to promote polyethylene–clay nanocomposites by in situ polymerization
Fecha
2013Registro en:
Applied Catalysis A: General 453 (2013) 142– 150
doi 10.1016/j.apcata.2012.12.012
Autor
Zapata, Paula A.
Belver, Carolina
Quijada Abarca, Juan
Aranda, Pilar
Ruiz Hitzky, Eduardo
Institución
Resumen
Two clay organo-heterostructures have been prepared and employed as fillers and catalyst supports for
the development of polyethylene–clay nanocomposites. The new silica–clay organo-heterostructures
have been obtained from two organoclays modified with tetramethoxysilane. In contrast to related
heterostructures reported previously the organic moieties are not removed by heating and their presence
intends to confer hydrophobicity to the interlayer region of the clay, even after delamination by
hydrolysis-polymerization of the alkoxysilane takes place. These organo-heterostructures were used
for preparing clay–polyethylene nanocomposites by in situ polymerizations in which the organoheterostructures
were added together with the metallocene catalyst, and by using the silica–clay as
support for the metallocene catalysts. The polymers formed when the organo-heterostructures were
used as support for the catalyst have higher molecular weights than the standard polyethylene formed
under homogeneous conditions. Moreover, the presence of the inorganic silica network developed in the
interlayer region of the organoclay favours the existence of a larger organophilic region in which it is
possible to accommodate both the catalyst and the monomer, and hence when the polymer grows in this
environment it can assist in the exfoliation of the clay layers inside the polyethylene matrix. The polymer
particle morphology improved with the presence of the clay in the polymerization. The molecular weight
for support systems presented an increasing ca. 40% compared to neat PE, and by TEM it was found that
the clay layers were well dispersed in the PE matrix.