Polypropylene Nanocomposites Attained by In Situ Polymerization Using SBA-15 Particles as Support for Metallocene Catalysts: Effect of Molecular Weight and Tacticity on Crystalline Details, Phase Transitions and Rheological Behavior Articles uri icon

authors

  • BARRANCO GARCÍA, ROSA
  • GARCIA PEÑAS, ALBERTO
  • BLAZQUEZ BLAZQUEZ, ENRIQUE
  • RESSIA, JORGE A.
  • QUINZANI, LIDIA M.
  • VALLES, ENRIQUE M.
  • GÓMEZ ELVIRA, JOSÉ M.
  • PÉREZ, ERNESTO
  • Cerrada, María L.

publication date

  • June 2023

start page

  • 1

end page

  • 26

issue

  • 11, 4261

volume

  • 28

Electronic International Standard Serial Number (EISSN)

  • 1420-3049

abstract

  • In this study, nanocomposites based on polypropylene are synthesized by the in situ polymerization of propene in the presence of mesoporous SBA-15 silica, which acts as a carrier of the catalytic system (zirconocene as catalyst and methylaluminoxane as cocatalyst). The protocol for the immobilization and attainment of hybrid SBA-15 particles involves a pre-stage of contact between the catalyst with cocatalyst before their final functionalization. Two zirconocene catalysts are tested in order to attain materials with different microstructural characteristics, molar masses and regioregularities of chains. Some polypropylene chains are able to be accommodated within the silica mesostructure of these composites. Thus, an endothermic event of small intensity appears during heating calorimetric experiments at approximately 105 °C. The existence of these polypropylene crystals, confined within the nanometric channels of silica, is corroborated by SAXS measurements obtained via the change in the intensity and position of the first-order diffraction of SBA-15. The incorporation of silica also has a very significant effect on the rheological response of the resultant materials, leading to important variations in various magnitudes, such as the shear storage modulus, viscosity and δ angle, when a comparison is established with the corresponding neat iPP matrices. Rheological percolation is reached, thus demonstrating the role of SBA-15 particles as filler, in addition to the supporting role that they exert during the polymerizations.

subjects

  • Chemistry
  • Industrial Engineering
  • Materials science and engineering
  • Renewable Energies

keywords

  • confinement; crystallites; hybrid particles; in situ polymerization; metallocene catalysts; nanocomposites; polypropylene; rheological percolation; sba-15 silica