High-density polyethylene

Class of Polyethylenes

If you want to learn more, please visit our website.

High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer derived from the ethylene monomer. Commonly referred to as "alkathene" or "polythene" when applied in HDPE pipes, HDPE possesses a high strength-to-density ratio, making it suitable for producing plastic bottles, corrosion-resistant piping, geomembranes, and plastic lumber. Furthermore, HDPE is widely recycled and is identified by the resin code "2".

As of recent reports, the global HDPE market has exceeded a volume of over 30 million tons.

Properties

Thermophysical properties of HDPE include:

• Density: 961 kg/m³
• Melting point: 131.8 °C (269.24 °F)
• Temperature of crystallization: 121.9 °C (251.42 °F)
• Latent heat of fusion: 188.6 kJ/kg
• Thermal conductivity: 0.54 W/m·°C at 20 °C
• Cable capacity: Data not specified
• Crystallinity: 61%

HDPE stands out due to its superior strength-to-density ratio, with densities varying between 930 to 970 kg/m³. Although HDPE's density is only slightly greater than that of low-density polyethylene (LDPE), its structure features minimal branching, resulting in robust intermolecular forces and higher tensile strength (approximately 38 MPa compared to 21 MPa for LDPE). This strength difference amplifies HDPE's specific strength.

HDPE is notably resistant to a wide range of solvents and is notoriously difficult to glue; joints are generally formed through welding. The specific physical properties can differ based on the molding process utilized during manufacturing. Different standard testing methodologies are employed to assess these properties, especially for applications like rotational molding where environmental stress crack resistance is vital.

Due to its advantageous characteristics, HDPE pipes are particularly suited for both drinking water systems and wastewater management.

Applications

• HDPE fibers can be spun into rope

• Disposable suits; nonwoven HDPE fabric

• Housewrap

• Plastic mailing envelopes

• Flexible HDPE pipes

• Corrugated HDPE pipe installation in a storm drain project in Mexico

• The monobloc chair

• Bottle crates

• Toys and playground equipment

• HDPE is used to make sturdy, oil-resistant bottles; clear plastic bags are made from LDPE.

• Milk jug

• HDPE jerrycans resist softening and swelling from aromatic components of fuels

• Roller on HDPE construction entrance mat

  For additional details, kindly visit ABOSN.

HDPE finds applications across numerous sectors, with the selection of HDPE primarily depending on its cost-effectiveness compared to other polymers.

In landfill applications, HDPE serves as an effective liner in United States subtitle D sanitary landfills. Large HDPE sheets are either extrusion welded or wedge welded to create a consistent chemical-resistant barrier capable of safeguarding soil and groundwater from waste contaminants.

Additionally, the pyrotechnics industry favors HDPE for mortars over steel or PVC due to its enhanced durability and safety; HDPE tends to rip rather than shatter, reducing the risk of shrapnel in case of malfunction.

HDPE's most significant utilization lies in the production of milk bottles, jugs, and other hollow goods via blow molding, representing approximately one-third of annual global production, which exceeds 8 million tonnes.

Countries like China, where HDPE beverage bottles were first imported, are witnessing a growing market for rigid HDPE packaging due to enhanced living standards. In populous emerging markets like India, infrastructural development increasingly employs HDPE in piping and cable insulation.

Production

Industrial synthesis of HDPE from ethylene can occur through Ziegler-Natta polymerization or the Phillips slurry process. The Ziegler-Natta method utilizes a combination of catalysts, including titanium tetrachloride, in conjunction with gaseous ethylene to produce HDPE. Meanwhile, the Phillips slurry method employs silica-based catalysts in a highly agitated polyethylene slurry.

The processing method significantly influences the properties of the resultant HDPE. The specific approach determines the microstructure, offering either extensive molecular weights and branching control with the Phillips slurry method or flexibility in polyethylene types with the Ziegler method. Molecular weight indicates the length of polyethylene chains, affecting characteristics like flexibility, yield strength, and melt temperature.

Post-synthesis, HDPE can be formed into various commercial products. Different industrial processes include injection molding for complex items like toys, extrusion for steady-state products such as pipes, blow molding for hollow forms (particularly bottles), and rotational molding for large-scale parts like chemical drums or kayaks.

Common Uses of High-Density Polyethylene

High-density polyethylene, commonly known as HDPE, is a versatile petroleum thermoplastic and the most utilized variant among the three types of polyethylene. When examined microscopically, HDPE exhibits a linear structure with minimal branching, contributing to its optimal strength-to-density ratio. This molecular structure allows HDPE to excel in applications requiring moisture resistance and cost-efficiency.

Developed during the 1950s for high-frequency radar cables in World War II, HDPE entered the commercial market soon after. Higher-density variants provide rigidity, while flexibility varies across low-density and high-density grades.

The Advantages and Disadvantages of HDPE

Despite its widespread use, there are several advantages and disadvantages to consider when selecting HDPE for your projects:

Advantages

• Cost-effective
• Temperature resilient ranging from -148 to 176 degrees Fahrenheit
• Non-leaching properties
• UV-resistant
• Dishwasher safe
• Resistance to most chemical solvents
• Stiff material properties

Disadvantages

• Poor weather resistance
• Flammability
• Prone to stress cracking
• Difficult bonding characteristics

4 Common Uses for HDPE

1. Plastic Bottles: Familiar to users through durable water bottles, HDPE is ideal for blow-molding applications, making it suitable for food and beverage containers due to its non-leaching nature and recyclability.
2. Toys: UV resistance contributes to maintaining color and texture in toys.
3. Chemical Containers: Due to its resistance to chemicals, HDPE is widely used in the packaging of household cleaners, motor oils, and antifreeze. The strength of these products often increases with color pigmentation.
4. Pipe Systems: The pipe-grade HDPE sheets display a higher molecular weight compared to standard HDPE, which enhances durability for piping and outdoor applications, capable of withstanding temperatures ranging from -220 to 180 degrees Fahrenheit.

ABOSN offers a diverse selection of industrial HDPE sheets, including pipe grade, smooth, and matte sheets tailored for a plethora of applications. Whether your order is large or small, we are equipped to fulfill your needs. Contact us today, or visit our website for more details.

For more information regarding Polyethylene HDPE board 4x8, feel free to reach out to us.

The Advantages of HDPE Include

• Affordability
• High quality construction
• Harsh temperature performance
• Non-leaching properties
• Resistance to UV radiation
• Robust chemical resistance
• Durability and stiffness
• Versatility across applications

The Disadvantages of HDPE Include

• Poor weathering capabilities
• Flammable nature
• Vulnerability to stress fractures
• Non-biodegradability
• Inability to compost
• Reactivity to oxidizing acids
• Reactivity to chlorinated hydrocarbons
• It has a high thermal expansion rate
• Poor thermal stability

The Top Uses for HDPE Include

• Shampoo bottles
• Toys
• Chemical containers
• Piping systems
• Milk jugs
• Recycling bins
• Grocery bags
• Inner linings of cereal boxes
• Flower pots