LDPE plastics are polyethylenes, polymers with simple and branched structures (4000–40 000 carbon atoms/polymer), making them less dense and crystalline in form. It is highly flexible and cheap to produce. It has good resistance towards acids, alcohols, esters, and bases making it a suitable material for food and hardware applications. This type of plastic is deemed safe.
LDPE manufacturing employs a radical polymerization process, where an excess of 99.9% pure ethene is compressed and passed into a reactor and initiator with oxygen or natural peroxides. The polyethene is then extruded and cut into fine granules ready for the blow molding process.
Polyolefins (LDPE, HDPE, PP) are a major type of thermoplastic. LDPE is widely used for manufacturing various containers, dispensing bottles, wash bottles, tubing, plastic parts for computer components, and various molded laboratory equipment. Its most common use is in plastic bags.
Unlike PET it is easier to identify in case of dispersion in the water as it is less dense, so it floats.
AKA “The wrinkly supermarket bag plastic”
HISTORY
Low-density polyethylene was first produced in 1933 in England by Imperial Chemical Industries Ltd. (ICI) during studies of the effects of extremely high pressures on the polymerization of polyethylene. ICI was granted a patent on its process in 1937 and began commercial production in 1939.
SAFETY
Plastic number 4 (Low-density polyethylene or LDPE) is considered one of the safest plastics that you can use today and it has no known health concerns. It doesn’t leach chemicals into food or beverage and can be recycled. It’s used to make items such as plastic bags, milk cartons, mats, and playground equipment.
Credits: Low-density polyethylene – Wikipedia and Get to Know the 7 Types of Plastic- Plastics 101 | by The Physics Society | Medium and Polyethylene (PE) | Properties, Structures, Uses, & Facts | Britannica
