Polyalkenes, such as poly(propene), are biodegradable because the strong carbon-carbon bonds ($C-C$) in their main chain are easily cleaved by environmental enzymes.

Condensation polymers, such as polyesters and polyamides, are biodegradable because the polar carbonyl carbon atoms ($C^{\delta +}=O^{\delta -}$) in their backbone are susceptible to nucleophilic attack by water.

Feedstock recycling refers to the process of sorting, washing, and melting waste polymers to remould them into new plastic items without breaking any covalent bonds.

The highly acidic hydrogen chloride gas ($HCl$) released during the incineration of poly(chloroethene) is neutralised in modern chimneys by reaction with an acidic scrub of sulfuric acid ($H_2{SO}_4$).