The Properties Of HDPE
Invented by Paul Hogan and Robert Banks of Phillips Petroleum in 1951, HDPE is quite a remarkable substance. When first invented, it was branded with the name ‘Marlex’, and it shot to fame in the form of the hula hoop craze of the 1950’s. The Hula Hoop is still remembered, but the name ‘Marlex’ has long fallen by the wayside, and the substance invented by Paul Hogan and Robert Banks now goes by the much less glamorous moniker of ‘HDPE’. Nowadays HDPE is used in a wide range of applications, from milk bottles, to children’s toys, and from the laboratory to the back garden, HDPE products are a part of most modern people’s lives. This is an examination of some of the physical and chemical properties of HDPE, which may be of interest to manufacturers, recyclers, and chemists alike.
The Structure of HDPE
HDPE is what is known as a linear polymer, which is a polymer molecule where all the atoms are linked together in a long chain. Unlike its less stable cousin, LDPE, which consists of many branching molecules, HDPE is a much denser plastic, and as such is much stronger than LDPE. HDPE is created by a catalytic process, and is prepared from a chemical compound known as ethylene.
HDPE Temperature Resistance
HDPE has a melting point of 130 degrees Celsius (266 degrees Fahrenheit), and is considered stable up to 120 degrees Celsius (248 degrees Fahrenheit). The minimum temperature that HDPE can be stable at is -100 degrees Celsius (- 148 degrees Fahrenheit). As is demonstrated by these numbers, HDPE can be relied upon to remain stable in most all environments. There are very few domestic applications where it would be exposed to temperatures greater than 120 degrees Celsius, although obviously the oven should be avoided, and HDPE products could never be used for the purpose of baking. HDPE products do stand up well in domestic freezers however, and can be used for the storing of foodstuffs.
HDPE Chemical Resistance
- HDPE is very resistant to alcohols, acids and bases.
- HDPE has a good resistance to vegetable oils, mineral oils, ketones, esters, and aldehydes.
- HDPE has little to no resistance to oxidizing agents and halogenated hydrocarbons.
Other Properties of HDPE
HDPE is very lightweight, absorbs little moisture, and possesses a high tensile strength of 4550 psi. In addition to these properties, HDPE is also very strong, and can take a good deal of impact before it becomes weakened. This property, combined with its lightness makes is a favorite in industrial applications where strength is needed, but a large weight is not desired.
HDPE does not:
Provide an effective oxygen barrier, or provide an effective CO2 barrier, so HDPE is therefore unsuitable for applications where airtightness is required.
Approved Uses for HDPE
HDPE has been approved of as a product for food packaging by various institutions, including the FDA, NSF and USDA. These organizations have stated that HDPE is quite safe as a contact packaging, as long as the HDPE is newly manufactured, and not processed from scrap.
Due to its high level of resistance to acids and bases, HDPE is quite commonly used in laboratory and health care applications.
Because of its rigidity and high resistance to chemicals, HDPE is considered an excellent material for pipes, as well as tanks and drums.
Other uses include: children’s toys, non carbonated beverage bottles, cutting boards, garden furniture, tanks, drums, laboratory equipment, shopping bags, toilet seat covers, manhole covers, and the list goes on as more and more applications are discovered for this eminently useful plastic.
HDPE Prices and Suppliers
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