Abstract
One of the most efficient and versatile ways to synthesize polyolefin nanocomposites is the in-situ polymerization of olefins in the presence of nano particles by metallocene catalysts. Metallocene/methylaluminoxane (MAO) catalysts are soluble in hydrocarbons and therefore they can be absorbed perfectly in solution onto the surface of particles or fibers and after addition of ethene or propene they can then catalyze a polyolefin film on the surface. Metallocene/MAO and other single site catalysts allow the synthesis of polymers with a precisely defined microstructure, tacticity, and stereoregularity as well as new copolymers with superior properties such as film clarity, high tensile strength and lower content of extractables. The polymer properties can be enlarged by the incorporation of nanofillers. The resulting polyethylene or polypropylene nanocomposites give a tremendous boost to the physical and chemical properties such as dramatically improved stiffness, high gas barrier properties, significant flame retardancy, and high crystallization rates.
Highlights
Within recent years, much research in academia and industrial laboratories has focused on the field of polyolefin nanocomposites because of their high potential as materials with novel properties such as improved mechanical properties stiffness, strength, toughness, increased heat distortion temperature, reduced permeability, and flame retardancy
We investigated the properties of polyethylene and polypropylene composites by the in-situ polymerization technique using different inorganic nano materials such as silica balls with a diameter of 200–250 nm, magnesium oxide, aluminium oxide, other inorganic materials as well as carbon nanotubes or fibers
Polyolefin nanocomposites open up an approach to new classes of materials with good property combinations
Summary
Much research in academia and industrial laboratories has focused on the field of polyolefin nanocomposites because of their high potential as materials with novel properties such as improved mechanical properties stiffness, strength, toughness, increased heat distortion temperature, reduced permeability, and flame retardancy. Melt compounding of polyolefins with nanoparticles often leads to an insufficient filler dispersion, especially at a high filler content, which leads to aggregation and intercalation, which in turn deteriorates the mechanical properties Such disadvantages can be solved by in-situ polymerization whereby the cocatalyst methylaluminoxane (MAO) can be adsorbed or anchored on the surface of the nanofillers such as particles, fibers, carbon nanofiber (CNF), multi-walled carbon nanotubes (MWCNT), thereby changing the surface to a hydrophobic one [16,17]. It was a goal of our investigations to use inorganic particles, especially silica balls for polyolefin nanocomposites and carbon nanotubes to increase the stiffness, formstability and other properties
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