What is the Difference Between HDPE LDPE and LLDPE

The key difference between HDPE LDPE and LLDPE is that HDPE has a low amount of long chain branching in its chemical structure and LDPE has comparatively a high amount of long chain branching whereas LLDPE contains a considerable amount of short chain branches in its chemical structure.

The term HDPE stands for high density polyethylene and the term LDPE stands for low density polyethylene while the term LLDPE stands for linear low density polyethylene.

1. Overview and Key Difference
2. What is HDPE
3. What is LDPE
4. What is LLDPE
5. HDPE vs LDPE vs LLDPE in Tabular Form
6. Summary

What is HDPE?

The term HDPE stands for high density polyethylene. HDPE is high density polyethylene, a polymer material that forms from the polymerization of ethylene monomers. It is a thermoplastic material (becomes moldable at a specific temperature and solidify upon cooling). This material has a high ratio between the strength and density of the polymer material. Therefore, it’s used in the production of plastic bottles, pipes, etc. The density range for this polyethylene material is 0.93 to 0.97 g/cm3.

Figure 01: HDPE

The advantages of using HDPE over other polymers include cost-effectiveness, ability to withstand high temperatures, non-leaching properties, resistance to UV radiation, resistance to many chemicals and stiffness. There are some disadvantages as well. The disadvantages include poor weather resistance, flammability, sensitivity to stress cracking, etc.

HDPE material is useful in the production of plastic bottles, toys, chemical containers, pipe systems, plastic bags, snowboards, fuel tanks in vehicles, etc.

What is LDPE?

The term LDPE stands for low density polyethylene. It is a thermoplastic material. The monomer of this polymer material is ethylene. LDPE was first produced in 1933 by Imperial Chemical Industries using the process of high pressure free radical polymerization. This is the most common method of production for LDPE even today.

The density range of LDPE is between 917 to 930 Kg/m3. This material is inactive at room temperature in the absence of strong oxidizers and some solvents (that can cause the material to swell). LDPE is quite flexible and tough. The appearance of LDPE is usually either translucent or opaque.

What is LLDPE?

The term LLDPE stands for linear low density polyethylene. It is a linear polymer with short-chain branching, and we produce it via copolymerization of ethylene with olefins having longer chains. We need to use low temperatures and pressures during this production. The final product of this process gives a narrow molecular weight distribution. Furthermore, the catalyst we use for this manufacturing process is the Ziegler catalyst.

Figure 02: Branched Polymer

We can do the polymerization in either the solution phase or the gas phase. Moreover, when considering its properties, LLDPE has high tensile strength, high impact and puncture resistance when compared to LDPE. Moreover, this material is very flexible. It can elongate under stress.

What is the Difference Between HDPE LDPE and LLDPE?

The term HDPE stands for high density polyethylene and the term LDPE stands for low density polyethylene while the term LLDPE stands for linear low density polyethylene. The key difference between HDPE LDPE and LLDPE is that HDPE has a low amount of long-chain branching in its chemical structure, and LDPE has comparatively a high amount of long-chain branching, whereas LLDPE contains a considerable amount of short-chain branches in its chemical structure.

The following infographic presents the differences between HDPE LDPE and LLDPE in tabular form.

Summary – HDPE vs LDPE vs LLDPE

The term HDPE stands for high density polyethylene. And the term LDPE stands for low density polyethylene. Meanwhile, the term LLDPE stands for linear low density polyethylene. The key difference between HDPE LDPE and LLDPE is that HDPE has a low amount of long chain branching in its chemical structure, and LDPE has comparatively a high amount of long chain branching, whereas LLDPE contains a considerable amount of short chain branches in its chemical structure.

Reference:

1. “Low-Density Polyethylene.” Wikipedia, Wikimedia Foundation, 21 June 2021.

Image Courtesy:

1. “Symbol Resin Code 2 HDPE” By Bhutajata – Own work (CC0) via Commons Wikimedia
2. “Branched polymer” By GKFX – Own work (Public Domain) via Commons Wikimedia