In situ formation of nanocomposites based on polyethylene and silica nanospheres

Abstract

Polyethylene nanocomposites containing silica nanospheres, synthesized by the sol-gel method, were produced via in situ polymerization. The silica nanospheres were added together with the catalytic system [metallocene catalyst and methylaluminoxane (MAO) as cocatalyst] directly to the reactor and used for the polymerization of ethylene. The polymerization activity increased slightly in the presence of 1 wt % silica nanospheres in comparison to the homogeneous polymerization sans filler. The Young's modulus of the nanocomposites increased 19-25% without a significant decrease in the elongation at break with respect to the neat polyethylene. The polymer particle morphology was also significantly improved with the incorporation of silica nanospheres.

Polyethylene Nanocomposites Obtained by in situ Polymerization via a Metallocene Catalyst Supported on Silica Nanospheres

“…The SiO 2 particles presented spherical morphology with diameters of ca. 80–100 nm, as reported in a previous work 22. The surface area of the SN was 61 m 2 · g −1 measurements by BET analysis.…”

“…Silica microparticle (Aldrich) was also used as comparison with nanosystems. Monodisperse spherical SiO 2 nanoparticles were prepared by hydrolysis of TEOS using a two stage mixed semi‐batch method as reported in a previous work 22, 23. Then, the nanoparticles were calcined for 4 h at 450 °C in order to control of OH groups in the silica surface.…”

“…Percent crystallinity of polymer were calculated using the enthalpy of fusion of an ideal PE having 100% crystallinity (289 J · g −1 ) as refs 15, 22, 25…”

“…Our group has prepared PE nanocomposites by in situ polymerization using untreated silica nanospheres (SN), with diameters of 80–100 nm synthesized by the sol–gel method, as filler 22. Our approach in this study was to place the nanospheres in contact with the cocatalyst (MAO) and the metallocene catalyst directly in the reactor.…”

FURTHER STUDIES ON HOMO- AND COPOLYMERIZATION OF STYRENE THROUGH CpTICl3-MAO INITIATOR SYSTEM

“…16 Viscosities were measured either in chloroform or in o-dichlorobenzene, depending on the solubility of the polymer, and intrinsic viscosities were determined by the one-point method. 17 DSC analyses were made by using a Rheometrics Scientific DSC apparatus with samples placed in a nitrogen atmosphere.…”