HDPE (high density polyethylene), LDPE (Low density polyethylene) and LLDPE (linear low density polyethylene) are three different 

types of polyethylene plastics. The differences between them are mainly reflected in the following aspects:

Density: HDPE has a higher density, LDPE has a lower density, and LLDPE is somewhere in between. This is due to the different 

polymerization reaction conditions and catalysts used in the production process.

Molecular structure: HDPE is a linear chain polymer with higher crystallinity, LDPE is an amorphous polymer composed of a longer 

branch chain, and LLDPE is a structure between a linear chain and a branch chain.

Physical properties: Each polyethylene has different physical properties due to its different molecular structure. HDPE has higher 

hardness, strength and stiffness, while LDPE has lower hardness and stiffness, but has higher toughness and good softness. LLDPE is 

somewhere between the two in terms of hardness, strength and toughness, and has high tensile properties.

Application field: Due to their different physical properties, these three types of polyethylene are different in application. HDPE is 

usually used to make bottles, pipes, containers, barrels and other products that require higher stiffness and hardness. LDPE is often 

used to make plastic bags, films, packaging materials and other products that need better softness and ductility. LLDPE is widely used 

in film, packaging film, garbage bags and so on.

It should be noted that the above is only a general feature introduction, the specific application and performance are also related to 

additives, processing conditions and other factors. In practical applications, suitable polyethylene types can be selected according to 

specific needs.

Environmental protection: Due to their different material structures, the environmental performance of these three types of

polyethylene is also different. HDPE has high crystallinity, relatively complete molecular chain, good thermal stability, and slow 

degradation rate, so it needs attention in waste treatment. LDPE and LLDPE, due to their low purity and easy to break molecular 

chains, have a faster decomposition rate and will not cause a wide range of environmental impacts.

Chemical stability: HDPE has good chemical stability, and the erosion degree of acid, alkali, solvent and other chemical substances is 

small. LDPE and LLDPE are relatively sensitive to chemicals due to their loose molecular structure and are easy to be eroded and 

dissolved.

Melting temperature: The melting temperature of HDPE is high, generally between 120-180 degrees Celsius. LDPE and LLDPE melt at 

a lower temperature of about 105-115 degrees Celsius.

Wear resistance: HDPE has good wear resistance and can resist wear and scratching. LDPE and LLDPE have relatively weak wear 

resistance and are easy to be scratched and worn.

Transparency: HDPE is usually translucent or opaque and is not easy to transmit light. LDPE and LLDPE usually have good transparency 

and can transmit light.

In general, HDPE has high strength, hardness and wear resistance, and is suitable for products requiring high rigidity and durability; 

LDPE has good flexibility, toughness and transparency, suitable for making films and packaging materials; LLDPE combines the 

characteristics of HDPE and LDPE, has high tensile properties and wear resistance, and is widely used in packaging films and garbage 

bags. The choice of which type of polyethylene to use depends on the requirements of the end product and the specific application 

scenario.