HDPE stands for high density polyethylene. It’s a generally-used thermoplastic resin made from pure gas or obtained by way of refining petroleum. Polyethylene can endure a low- or excessive-strain process of forming polymer chains (polymerization). High-density polyethylene has longer chains with fewer aspect branches that gives higher crystallinity, and thus greater stiffness, hardness, energy and heat resistance. HDPE is designated with the recycling code No. 2. All No. 2 plastics are some sort of HDPE.
Blow molding is a producing course of that includes melting plastic and shaping it right into a preform. Subsequent, pressurized gas expands the recent preform which is then pressed in opposition to a mold cavity. Blow molding is commonly used for milk and detergent containers.
An injection-mold process consists of delivering materials into a heated barrel after which mixing and forcing it into a mold cavity. The plastic cools and hardens to the configuration of the mold cavity. The cavity is mostly comprised of steel or aluminum and designed specifically to form the options of the desired shape. Injection molding is usually used for butter and yogurt containers.
Coloured and natural HDPE
HDPE may also involve additive coloration pigments combined in when the plastic is heated. Natural HDPE refers to a transparent or semi-translucent colour. These bottles have good barrier properties and stiffness and are good for packaging merchandise that don’t final long, such as milk. Colored HDPE containers have better stress crack resistance as the pigments assist implement chemical resistance. They’re commonly used for merchandise equivalent to laundry detergent and shampoo that have lengthy shelf lives.
“MakeItFrom.com”: HDPE vs LDPE
“What’s Blow Molding” Plastic Blow Molding Handbook, Norman C. Lee, 1990
“Manufacturing Processes Reference Information”; Robert Todd, Dell Allen, and Leo Alting; 1994