HDPE stands for prime density polyethylene. It’s a commonly-used thermoplastic resin made from natural gasoline or obtained by refining petroleum. Polyethylene can undergo a low- or high-strain process of forming polymer chains (polymerization). High-density polyethylene has longer chains with fewer facet branches that provides increased crystallinity, and thus larger stiffness, hardness, power and heat resistance. HDPE is designated with the recycling code No. 2. All No. 2 plastics are some kind of HDPE.
Blow-molded HDPE
Blow molding is a producing course of that entails melting plastic and shaping it into a preform. Subsequent, pressurized gas expands the new preform which is then pressed against a mold cavity. Blow molding is often used for milk and detergent containers.
Injection-molded HDPE
An injection-mold process consists of delivering materials right into a heated barrel and then mixing and forcing it right into a mold cavity. The plastic cools and hardens to the configuration of the mold cavity. The cavity is usually comprised of steel or aluminum and designed specifically to form the options of the desired shape. Injection molding is often used for butter and yogurt containers.
Coloured and pure HDPE
HDPE also can contain additive colour pigments mixed in when the plastic is heated. Pure HDPE refers to a transparent or semi-translucent shade. These bottles have good barrier properties and stiffness and are good for packaging merchandise that do not final long, similar to milk. Coloured HDPE containers have better stress crack resistance as the pigments help implement chemical resistance. They’re generally used for merchandise comparable to laundry detergent and shampoo which have long shelf lives.
“MakeItFrom.com”: HDPE vs LDPE
“What is Blow Molding” Plastic Blow Molding Handbook, Norman C. Lee, 1990
“Manufacturing Processes Reference Information”; Robert Todd, Dell Allen, and Leo Alting; 1994
