Addition polymers
In addition polymerisation, many alkene monomers open their C=C π bonds and join into a long saturated chain; no other product forms. The repeat unit is drawn by turning C=C into C–C with extension bonds through brackets: ethene → poly(ethene), chloroethene → poly(chloroethene) (PVC), propene → poly(propene). Poly(alkenes) are unreactive (saturated, non-polar C–C and C–H bonds), so they're non-biodegradable. Disposal: landfill (lasts centuries), incineration (energy recovery but CO₂ and, for PVC, HCl and dioxins), recycling, or biodegradable alternatives.
≈ 35 min