Linear low-density polyethylene (LLDPE) 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. Linear low-density polyethylene differs structurally from conventional low-density polyethylene (LDPE) because of the absence of long chain branching. The linearity of LLDPE results from the different manufacturing processes of LLDPE and LDPE. In general, LLDPE is produced at lower temperatures and pressures by copolymerization of ethylene and such higher alpha-olefins as butene, hexene, or octene. The copolymerization process produces an LLDPE polymer that has a narrower molecular weight distribution than conventional LDPE and in combination with the linear structure, significantly different rheological properties.

LLDPE is a polyethylene with a density < 965 kg/m, produced by a low-pressure process. Polyolefins are produced from olefin (alkene) monomers because the olefins contain a reactive double bond. The starting material, ethylene, is called the monomer and the final product consisting of many thousands of bound ethylene units is called the polymer. Co-monomers (higher alpha olefins such as butene, hexene, octene) are used to control the density and other physical properties.

LLDPE has penetrated almost all traditional markets for polyethylene; it is used for plastic bags and sheets (where it allows using lower thickness than comparable LDPE), plastic wrap, stretch wrap, pouches, toys, covers, lids, pipes, buckets and containers, covering of cables, geomembranes, and mainly flexible tubing. In 2013, the world market for LLDPE reached a volume of $40 billion. LLDPE manufactured by using metallocene catalysts is labelled mLLDPE. Globally, around 80% of LLDPE goes into film applications such as food and non-food packaging, shrink/stretch film and non-packaging uses. The trend in food packaging films is towards high performance film structures that are less permeable to increase shelf life and enhance flavours. Growth is occurring from the transition of items packaged in rigid containers to high quality flexible packages. LLDPE is being used in extrusion coating applications where it helps protect the contents of liquid containers, primarily for paper and paperboard packaging.