Low Density Polyethylene (LDPE) is a semi-rigid and translucent polymer. Compared to HDPE, it has a higher degree of short and long side-chain branching. It is produced made from the monomer ethylene at high pressure (1000-3000 bar; 80-300°C) via free radical polymerization process.
The average polymer molecule contains 4000-40,000 carbon atoms, with many short branches.
Two basic processes used for the production of low density polyethylene: stirred autoclave or tubular routes. The tubular reactor has been gaining preference over the autoclave route due to its higher ethylene conversion rates.
Low Density Polyethylene Structure
Low Density Polyethylene exhibits good resistance to alcohols, dilute alkalis and acids. It has a limited resistance to aliphatic and aromatic hydrocarbons, mineral oils, oxidizing agents and halogenated hydrocarbons. Low Density Polyethylene can resist temperatures up to 80°C continuously and 95°C for shorter times. This limits its usage in applications requiring extreme temperatures.