Low-Density Polyethylene, also known as LDPE plastic, is a soft and flexible polymer. Unlike the High-Density Polyethylene (HDPE), which is known for its high specific strength and heat resistance, LDPE has a lower density, strength, and temperature resistance in comparison. This lower density and resistance is due to the slight difference in the polybag structure in which the LDPE features a higher degree of short and long side-chain branching—manufactured at a high pressure of 1000-3000 bar and a low temperature of 80ºC-300°C. This process is known as Free Radical Polymerisation, a type of chain-growth polymerisation that occurs when the polymer forms through consecutive additions of unsaturated monomer molecules to an active, free radical centre. The formation of this plastic material makes it a suitable polymer with superb processability. It has a high impact strength at low-temperature levels, chemical resistance, excellent electrical insulator, good weatherability, low water absorption, and transparency in thin foil film. Furthermore, it also meets the FDA regulations, making it safe for contact with food products.
Categorised and featured as the number 4 plastic, the primary uses of the LDPE are for film-related applications. Typical products manufactured using this material include food plastic bags, shrink wrap, stretch film, and other packaging solutions. These are made possible due to the physical properties of the plastic material, which provides it excellent chemical resistance against chemicals such as alcohols, dilute acids and alkalis, and other elements that include moisture, dirt, dust, oil, and grease. Furthermore, it is also FDA approved, making it safe for contact with food products.