Rheological Characterization of Molten Ethylene-a-olefin Copolymers Synthesized with Et[Ind]2 ZrCl2/MAO Catalyst

MARCELO VILLAR; MARCELO DANIEL FAILLA; RAÚL QUIJADA; RAQUEL SANTOS MAULER; ENRIQUE M. VALLÉS; GRISELDA GALLAND; LIDIA MARÍA QUINZANI

POLYMER

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2001 vol. 42 p. 9269 - 9279

0032-3861

Este es uno de los 5 trabajos elegidos como producción más relevante (ver justificación en CV ampliado).The linear viscoelastic behavior of copolymersof ethylene with 1-hexene, 1-octene, 1-decene and 1-octadecene prepared withEt[Ind]2 ZrCl2/MAO is analyzed.  The copolymers with a-olefin concentration greater than approximately 14 mol%have the simple rheological behavior with temperature that may be associated tolinear polyethylenes with short chain branches. On the other hand, the polymers having comonomer concentration lowerthan approximately 14 mol% are thermorheologically complex materials.  The rheological behavior of these copolymersmay not be explained solely by the presence of long chain branching.  A dendritic-like molecular structure withbranches-on-branches has to be considered to explain the complexity observed inthe case of the ethylene copolymers with low comonomer concentration andethylene homopolymer.  The complex chainstructure would be the result of the incorporation of branched macromonomers inthe polymers produced by single-site catalysts. The level of branching andcomplexity of molecular structure increases as the comonomer concentrationdecreases.  No dependence with the lengthof the a-olefin was found in any of the analyzedparameters.