polyolefiini

Polyolefin is a family of polymers derived from olefin monomers, most notably ethylene and propylene. They are saturated hydrocarbons with carbon–carbon backbones and few or no heteroatoms, giving chemical resistance, low moisture absorption, good electrical insulation, and a broad range of mechanical properties that can be tailored by branching and tacticity.

Among polyolefins, polyethylene (PE) and polypropylene (PP) are the most widely produced. PE grades range from highly crystalline high-density polyethylene (HDPE) to more branched low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE). Isotactic and syndiotactic polypropylene are crystalline and stiff at room temperature, whereas atactic PP is amorphous and softer. Copolymers with other α-olefins modify flexibility, clarity, and toughness.

Polyolefins are produced by catalytic polymerization of olefin monomers using Ziegler–Natta or metallocene catalysts. Industrial processes run at low pressure (for HDPE, LLDPE, PP) or high pressure (historic LDPE). Copolymerization and blending enable a wide range of physical properties for specific applications.

Applications span packaging films and containers, pipes and fittings, automotive and consumer components, and medical devices for particular grades. They are lightweight and cost-effective but are not biodegradable; recyclability is well established, with HDPE, LDPE, and PP streams common in recycling programs. Environmental considerations include energy use and end-of-life disposal.