Polyolefin
Named after the Nobelists Karl Ziegler and Giulio Natta, these catalysts are prepared by treating titanium chlorides with organoaluminium compounds, such as triethylaluminium.
Polyolefin properties range from liquidlike to rigid solids, and are primarily determined by their molecular weight and degree of crystallinity.
Alpha-olefins such as 1-hexene may be used as co-monomers to give an alkyl branched polymer (see chemical structure below), although 1-decene is most commonly used for lubricant base stocks.
These alkyl groups, which can shape themselves in numerous conformations, make it very difficult for the polymer molecules to align themselves up side-by-side in an orderly way.
[citation needed] Polyolefin sheets or foams are used in a wide variety of packaging applications, sometimes in direct contact with food.
[14] Polyolefin elastomer POE is used as a main ingredient in the molded flexible foam technology such as in the fabrication of self skinned footwear (for example, Crocs shoes), seat cushions, arm rests, spa pillows, etc.
[17] Piping systems for the conveyance of water, chemicals or gases are commonly produced in Polypropylene, and to a much greater extent Polyethylene.
[18] Polypropylene is commonly used in car bumpers, interior trims, and other components[19] where TiO₂ is added to improve the UV stability of the plastic, ensuring that parts do not degrade or lose color when exposed to sunlight over time.
[21] Despite hype rosier than practice, real recycling of polyolefins has been insufficient in the decades since they became ubiquitous, often not due to technical limitations but because of economic realities.
[22] Polyolefin waste can potentially be converted into many different products, including pure polymers, naphtha, clean fuels, or monomers,[23] but only to the extent that money-losing processes are not required, in the reality of the business world.
In the 2020s, improved catalysts have been developed that may bring commercial recycling of polyolefins closer to a circular economy of recovery of the monomers, more comparable to the existing situation with PET polyester bottles.
