Which polymerization method would be most suitable for creating a polymer used in flexible packaging, considering the desired properties of flexibility and strength?

For flexible packaging, a polymer that is both tough and pliable is needed, so polyethylene or polypropylene are common choices. These polymers are most efficiently produced by free‑radical polymerization of ethylene or propylene, which gives long chains that can stretch and absorb stress. The reaction is usually carried out in bulk or emulsion, allowing the chains to grow rapidly and form a dense, yet flexible, network. For example, a bulk free‑radical polymerization of ethylene at 200 °C produces high‑density polyethylene that is strong enough to seal food while remaining bendable. Thus, free‑radical polymerization is the best method for creating a flexible, strong packaging polymer.