HDPE Melting Point | HDPE Repeat Unit, and More

Hello, Wonderful people. I hope you’re doing well. Today I’m going to share a very interesting piece on HDPE Melting Point, Repeat Unit, Properties, Advantages & Disadvantages.

HDPE has a melting point that falls within the range of approximately 120°C to 180°C (248°F to 356°F), with an average melting point of approximately 130°C (266°F).

Nevertheless, it is crucial to consider that the melting point of HDPE can differ based on the material’s grade and quality. For example, HDPE materials of superior quality with higher degrees of crystallinity will possess higher melting points compared to materials of inferior quality with lower degrees of crystallinity.

The temperature at which a solid substance transitions from a solid to a liquid state is known as its melting point. In the case of HDPE, its melting point is influenced by its degree of crystallinity. HDPE is categorized as a semi-crystalline polymer due to its combination of crystalline and amorphous regions. Factors such as cooling rates, processing temperature, and molecular weight can affect the degree of crystallinity, leading to variations in the melting point.

Name and Identification of the Polymer

Polymer Class
High-Density Polyethylene
Common Names
HiTec, Playboard, Paxon, King Colorboard, Densetec, Polystone, King PlastiBal, and Plexar.
Acronym HDPE
CAS # 9002-88-4
Repeat Unit
CurlySmiles C{-}C{n+}

Thermo-Physical Properties 

Property Value
Melting Point 130 °C (266°F)
Density 0.960 g mL-1
Heat Deflection Temperature, 0.5 MPa 72 °C
Heat Deflection Temperature, 1.8 MPa 77 °C
Coefficient of Thermal Expansion x 10-5 14 cm °C
Thermal Conductivity 0.42 W/ mk
Shore Hardness, D Scale 55-67

Mechanical Properties 

Property Value
Tensile Strength, Break at 23 C 32 MPa
Tensile Strength, Yield at 23 C 26 MPa
Elongation, Break 600-1300%
Elongation, Yield 10-18%
Tensile Modulus at 23 C 900-1500 MPa
Flexural Modulus 970-1250 MPa
Izod Notched
71-155 J/m (kJ/m2)
Izod Unnotched No Break J/m

Electrical Properties 

Property Value
Dielectric Strength
2.1-3.5 V/mm x 104
Volume Resistivity
6 x 1015 Ohm-cm
Dielectric Constant @ 1 MHz 2.2-2.4
Dissipation Factor @ 1 MHz 0.0001 – 0.0005

Fabulous Read – Polypropylene Melting Point, Properties and More

The melting point of HDPE is a critical factor to consider during its processing and manufacturing. In the process of shaping or molding HDPE into the required form, the material is heated to a temperature higher than its melting point.

HDPE’s high melting point is a critical feature that guarantees the material’s shape and strength are preserved even in demanding circumstances. In the construction sector, HDPE is utilized to create pipes and fittings that encounter high temperatures and pressure. The high melting point of HDPE assures that these products can endure harsh conditions without experiencing degradation or melting.


HDPE is a beneficial material with many salient advantages. Let us have a look at some of them:

  1. One of HDPE’s standout features is its malleability and moldability, which improves its applications substantially in the infrastructure industry. A good example is the underground piping sector, where HDPE is the most preferred plastic material, thanks to its good weather ability and long-lastingness.
  2. HDPE has an outstanding strength-to-weight ratio of 0.93 to 0.97 g. That might not seem very impressive compared to LDPE. However, HDPE’s more linear structure with little branching gives it an edge over LDPE with greater tensile strength and greater molecular structure.
  3. It is corrosion-resistant, has good rigidity, and has a high melting point of 130 to 210°C. It’s difficult to melt, but its liquid form is easily processable to manufacture products like water tanks, shampoo bottles, cutting boards, detergent bottles, etc.
  4. It is easily recyclable and doesn’t lose its ability the slightest after being recycled. In fact, recycled material is said to be as good as virgin material.


  1. Non-resistant to chlorinated hydrocarbons.
  2. Non-resistant to oxidizing acids.
  3. High flammability
  4. High thermal expansion


Below are the frequently asked questions on the melting point of HDPE. Let’s dig deep to know more.

Is HDPE safe to melt?

HDPE doesn’t get sticky once melted and can’t be easily removed once it cools down and while burning. If not added with any additives, it will burn clean and won’t release any toxic fumes. However, when you add pigments, antioxidants, antistats, and other lubricants, the outcome differs, and toxic fumes are released. So, in a nutshell, it’s fine to burn HDPE using general laboratory equipment.

What type of material is HDPE?

HDPE comes from a polyethylene family of thermoplastics and is produced from the monomer ethylene. Therefore, it is also sometimes referred to as “alkathene” or “polythene” when used for HDPE pipes.

Why HDPE melting point is higher than LDPE?

HDPE has a more linear and crystalline structure, and LDPE is softer and more flexible. Their fundamentally different internal composition results in differences in many physical attributes, and melting point is one of them.

Why is HDPE being used more in Hospitals?

HDPE is becoming very popular these days for healthcare and medical applications. Its salient features include high impact resistance, low moisture absorption, corrosion resistance, chemical resistance, and easy processing. Hospitals rely on HDPE to create cost-effective and dependable medical devices that don’t splinter, rot, and retain bacteria.

Can I recycle HDPE and LDPE together?

Unlike other plastics, HDPE and LDPE are miscible to be recycled together, but it is advisable to recycle them separately to keep their physical properties intact.

Suggested Read 

The Conclusion 

That was all I had to say about HDPE melting point, properties, repeat unit, advantages & disadvantages.

To summarize, HDPE is a versatile and robust material that has various applications. Its melting point is a crucial property that plays a significant role in its processing and use. The melting point of HDPE typically ranges from 120°C to 180°C (248°F to 356°F), with an average melting point of 130°C (266°F). The degree of crystallinity is a factor that can influence the melting point, and careful temperature control during processing is necessary to prevent material degradation.

The high melting point of HDPE ensures that it can endure harsh conditions and maintain its strength and durability, making it an ideal material for use in diverse applications.

Thanks for bearing with my awful writing. Share your thoughts and questions in the comment box.

Have an outstanding day ahead.

2 thoughts on “HDPE Melting Point | HDPE Repeat Unit, and More”

  1. Thanks for taking the time to collect the information and write this article. I’m not a chemist, I’m a tinkerer, but I understood what your wrote. Nicely done, Sagar.


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