Question

Why can’t chemical recycling—that is, the conversion of polymer to monomers and re-conversion of monomers to polymer—be done easily with HDPE and LDPE?

Short answer

Answer

Because these polymers are both long chains of CH₂ groups joined together in a linear form. Since there are only C-C bonds and no functional groups in the polymer chain, there are no easy methods to convert polymers to their monomers.

This process is readily accomplished only when the polymer backbone has hydrolyzable functional groups.

Step-by-step solution

Polymer

Polymers are formed by “repeating units” called monomers. There are different types of polymers based on the origin, composition, heat, molecular force, polymerization modes, and so on.

HDPE and LDPE

High density poly-ethylene (HDPE) is formed by ethylene monomer/petroleum. It is harmless and used in both rigid and soft bottles.

Low density poly-ethylene (LDPE) is formed by ethylene monomer. It is not suitable for rigid substance as it is known for its softness and corrosion resistance.

Reason

Chemical recycling of HDPE and LDPE is not easily done because these polymers are both long chains ofCH₂ groups joined together in a linear form.

Since there are only C-C bonds and no functional groups in the polymer chain, there are no easy methods to convert the polymers to their monomers. This process is readily accomplished only when the polymer backbone has hydrolyzable functional groups.