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Use of food contact materials is required: potential food contamination is prohibited. Strict standards of cleanliness and processing must be followed. The most common material in milk packaging is high density polyethylene (HDPE), recycling code 2. Low density polyethylene (LDPE) and polyester (PET) [1] are also in use.
LDPE has SPI resin ID code 4 Schematic of LDPE branching structure. Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene.It was the first grade of polyethylene, produced in 1933 by John C. Swallow and M.W Perrin who were working for Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. [1]
A water bottle. Worldwide, 480 billions of plastic drinking bottles were sold in 2017 (and fewer than half were recycled). [1] A plastic bottle of antifreeze Large plastic bottles of water. A plastic bottle is a bottle constructed from high-density or low density plastic. Plastic bottles are typically used to store liquids such as water, soft ...
HDPE is known for its high strength-to-density ratio. [4] The density of HDPE ranges from 930 to 970 kg/m 3. [5] Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. [6]
The most commonly produced plastic consumer products include packaging made from LDPE (e.g. bags, containers, food packaging film), containers made from HDPE (e.g. milk bottles, shampoo bottles, ice cream tubs), and PET (e.g. bottles for water and other drinks). Together these products account for around 36% of plastics use in the world.
Polyethylene was first synthesized by the German chemist Hans von Pechmann, who prepared it by accident in 1898 while investigating diazomethane. [12] [a] [13] [b] When his colleagues Eugen Bamberger and Friedrich Tschirner characterized the white, waxy substance that he had created, they recognized that it contained long −CH 2 − chains and termed it polymethylene.
A December 2024 study in the journal Chemosphere incorrectly calculated the amount of potentially toxic flame retardants that could be present in some black plastic household products such as ...
HDPE: Inert, thermally stable, tough and high tensile strength: Bottles, pipes, inner insulation (dielectric) of coax cable (see also PTFE), plastic bags, etc. Polypropylene: PP: Resistant to acids and alkalies, High tensile strength: Auto parts, industrial fibers, food containers, liner in bags, dishware and as a wrapping material for textiles ...