The Process of Recycling HDPE

Recycling of High-Density Polyethylene

High-Density Polyethylene (HDPE) is a versatile plastic polymer with a specific gravity of 0.95, making it suitable for various applications. Its low density and great tensile strength make it an ideal material for containers holding liquids. HDPE cannot be autoclaved like polypropylene (PP), but it can be sterilized in autoclaving settings.

HDPE (or PEHD) polyethene waste recycling

High-Density Polyethylene, often known as HDPE or PEHD, is a plastic polymer that may be used in a variety of settings due to its adaptability.

The specific density of high-density polyethene is slightly higher than that of low-density polyethene, as the name would imply. HDPE’s lack of branching accounts for its unique physical features, which are low density and great tensile strength. HDPE is a linear polymer because the lack of branching allows for a more densely packed structure. Using targeted catalysts during manufacturing allows for directional control and minimizes branching.

HDPE Characteristics and Uses

HDPE is crucial in the production of a wide variety of goods because of its many useful qualities. HDPE, having a specific gravity of 0.95, is quite dense in comparison to other polymers. HDPE can withstand heat of up to 120 °C while maintaining its hardness and impact resistance.

When compared to polypropylene (PP), HDPE cannot be autoclaved. Products can be sterilized in autoclaving settings by subjecting them to high pressures and temperatures. Please refer to the following article for further details on PP.

HDPE can appear opaque or translucent, depending on the light source.

HDPE is commonly used for milk containers, Tupperware, shampoo bottles, bleach bottles, and motor oil bottles due to its strength and durability. HDPE does not readily absorb liquid, making it an ideal barrier material for containers holding liquids. About eight million tons of the sixteen million tons of HDPE produced annually are utilized for containers.

HDPE also has high chemical resistance, making it a popular choice for usage in hospitals and research facilities. It can withstand exposure to a wide variety of chemicals without breaking down or being weakened.

Extra applications of HDPE include:

• Plastic bags for groceries
• Trays
• Tanks

Food storage containers (several food agencies have given HDPE their seal of approval for direct food contact)

• Pipe unions
• Hinges
• Knife blocks
• Use armour

How does one recycle HDPE?

HDPE is one of the most recyclable plastic polymers and is therefore accepted at recycling facilities all over the world. Most recycling services will collect HDPE materials and transport them to massive processing centres.

The plastic is first washed and processed to remove any contaminants. The next step is to homogenize the plastic so that only HDPE can be used. Other plastic polymers can harm the recycled product, if there are any.

HDPE has a density of between 0.93 and 0.97 g/cm3. This makes sink-float separation a viable option for separating these polymeric polymers from PET, whose density is 1.43–1.45 g/cm3. HDPE cannot be separated using the sink-float method because its specific density is equivalent to that of PP. Unless the plastic is too black and absorbs the infrared waves, near-infrared radiation (NIR) approaches can be used in this situation.

To further purify the polymer, HDPE is shredded and melted down. After the plastic has been melted, it is cooled into pellets for industrial use.

A baler, which compacts post-consumer trash, is useful in recycling operations because it reduces the amount of energy needed to transport the material.

HDPE recycling can also be done in modest fashion at home. When properly cleaned, milk bottles can be used again and again. Purchasing plastic bottles in bulk is another viable alternative for reducing waste generated by packaging.

Similarly, carrier bags can be used more than once before being tossed. Used carrier bags can be recycled at a number of designated locations at many large supermarkets. Some plastic films have reminders to recycle them with grocery store shopping bags rather than throwing them away at the curb.

HDPE recycling is made easier by the inclusion of a resin code, which is a generic number provided to various plastic polymers for the purpose of sorting them. ‘2’ is the resin identification code for HDPE, which stands for high-density polyethylene.

HDPE Recycling’s Positive Impact on the Environment

HDPE has a massive market, with annual sales of over 30 million tons.

The bulk of bags are still made from HDPE, despite the fact that the amount of plastic used in plastic bags has decreased by roughly 70% in the previous 20 years, mainly due to the development of reusable canvas bags and the usage of biodegradable materials. The rising middle classes in China and India are driving up demand for HDPE packaging, while the country’s booming manufacturing sector is driving up demand for HDPE pipes and cables.

Because of how long it can take for HDPE to disintegrate, it’s crucial that all HDPE bags and containers be recycled and reused.

The advantages of HDPE recycling are numerous. To give just one example, the production of an item from recycled HDPE is more economically viable than the production of ‘virgin’ plastic.

HDPE, like many plastic polymers, is manufactured using significant amounts of fossil fuels; 1.75 kilograms of oil are required to make just 1 kg of HDPE.

Recycled HDPE can be used in the production of a wide variety of novel goods, such as:

• Rope
• Toys
• Piping
• Waste containers
• Litter boxes

HDPE has been shown by scientists to be recyclable at least ten times.

HDPE and PET, which together make up 97% of plastic bottles in North America, are among the easiest materials to recycle, leading many scientists to wonder why their recycling rate is not greater. The overall amount of plastic bottles recycled fell by 71 million pounds in 2016 compared to 2015, according to research published in November 2017 by the Association of the American Chemistry Council (ACC) and Plastic Recyclers (APR).  According to the data, HDPE bottle collection dropped from 34.4% in 2015 to 33.3% in 2016, with a total of 1112.1 million pounds collected.