High-density polyethylene (HDPE) High-density polyethylene or polyethylene high-density is a polyethylene thermoplastic made from petroleum. Semi rigid, Sinks in water, Resistance to moisture, permeability to gas.
Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. Flexible, not crinkly. Ease of processing, Ease of sealing, barrier to moisture.
Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins.