Polyethylene (LDPE, HDPE, LLDPE)

LDPE: low density polyethylene

HDPE: high density polyethylene

LLDPE: Linear Low Density Poly Ethelene

The difference between these products is only in their density and molecular weight, which has made them suitable for use in various industries.

LDPE

Light polyethylene or low-density polyethylene or LDPE, short for Low Density Poly Ethelene, is obtained from the production of polyethylene with a high-pressure process in tubular reactors under a pressure of 1600 atmospheres and at a temperature of 200 degrees Celsius. Compared to HDPE, LDPE has more branching in its molecular structure and, as a result, it has less crystallinity

This type of polyethylene is a semi-hard and semi-transparent polymer that is the result of high pressure polymerization.

Properties of light polyethylene:

• Melting point around 105 to 115 degrees Celsius
• Density 0.91 to 0.94 grams per cubic centimeter
• Good resistance to alcohols, alkalis and dilute acids

Limited resistance to aliphatic and aromatic hydrocarbons, mineral oils, oxidizing agents and halogenated hydrocarbons.

• Temperature resistance up to 80°C continuously and 95°C for a short time
• Low cost and affordable with good processing capability
• High resistance to air erosion
• Very good electric current insulation properties
• Very low water absorption and humidity
• High cracking ability against vibration

Low resistance, low hardness and low temperature capacity, which makes it impossible to use it to produce products that require high temperature in their process.

• High gas permeability, especially carbon dioxide gas
• Low resistance to ultraviolet radiation
• Very high flammability

Light polyethylene has many applications in various industries and production of various products due to its advantages and characteristics. This material is mostly used in container production industries, material transportation and distribution tankers, detergent and hygiene bottles, some agricultural irrigation equipment, plastic packaging for computer parts and various laboratory equipment. The most popular application of low density polyethylene is in the plastic bag manufacturing industry.

HDPE

HDPE is a material that has high impact resistance even at -80°C, it can be sterilized and easily used up to 80°C without pressure. Due to its density, molecular weight and the method used for its production, heavy polyethylene has a series of advantages that justify its use over similar materials. Its properties are:

• High resistance to impact, moisture and chemicals
• Affordable price
• Fast processing with all thermoplastic methods
• Low resistance to air erosion
• Low temperature capacity
• Flammability
• High thermal expansion
• Due to the properties of heavy polyethylene, this material has many uses, including making plastic bottles, toys, chemical containers, pipes and irrigation equipment.

LLDPE

Linear low density polyethylene or LLDPE (Linear Low Density Poly Ethelene) is a member of the linear polyethylene family and is structurally different from ordinary low density polyethylene (LDPE) due to the absence of long chain branches in LLDPE. .

The tensile strength of LLDPE and its resistance to impact and damage are higher than LDPE. Low density linear polyethylene is very flexible.

This type of polyethylene can be used to make thinner films with better resistance to environmental pressures.

• This material has a very good resistance to chemicals and is a very good insulator for electric current.
• In general, polyethylene is used in plastic industries, food packaging, pharmaceutical packaging, plastic bag production, toy production, production of various plastic covers and protectors, production of pipes and fittings, production of cables, geomembranes and production of flexible pipes. It is used (in medical equipment).
• This material is inexpensive and its price is affordable.
• Low-density linear polyethylene or LLDPE has relatively low water absorption due to its plasticity.
• Resistance to air erosion and high flexibility have also made it used in the production of water pipes and hoses in the industries of producing pipe and fittings products and irrigation equipment and greenhouses.

With all the positive features that linear low-density polyethylene or LLDPE has, but it is more difficult to process than LDPE. Its gloss is lower than LDPE and its thermal resistance is lower than its family.