Low-density polyethylene – LDPE is terminologically composed of two terms monomer meaning single part and ethylene which is a hydrocarbon with the formula C 2 H 4. Lightweight polyethylene was produced in 1933 under very high pressure and along with the radical release of polymerization by the British company ICT. Also, the rate of degradability of this material in nature according to the EPA or environmental protection test is equal to 5.7%, which is determined by the degradability number 4. Despite the fact that many polymer products have been produced and industrialized in global markets, today LDPE is considered as one of the most important products in the plastic industry, so that in 2013, the revenue of this product in the markets around the world was about $ 33 billion. it is arrived .

Properties of lightweight polyethylene - LDPE

LDPE densities range from 0.91 to 0.940 g / m3. It is inactive at room temperature unless exposed to strong oxidizing agents and some solvents. LDPE can withstand 80 ° C continuously but retains its cross-sectional shape at 95 ° C. This material produces semi-transparent and somewhat opaque products that have a very high flexibility and hardness.

Durability of lightweight polyethylene - LDPE

Very high resistance (does not react chemically) in dilution, dissolution in acids, alcohols, bases and corrosives
Suitable resistance to chemical reaction against aldehydes, ketones and vegetable oils
Low resistance to chemical reactions and interactions with aliphatic and aromatic hydrocarbons, mineral oils and oxidizing agents
Very low resistance (not recommended) in applications where halogenated hydrocarbons are present.

A practical point that should be considered is the different grades of nylon. A type of grade should be used for each consumption and application. For example, food grades usually use food grades such as 020. Or for shearing or vacuum grades, grade 0075 can be used along with other supplements. From plastic containers, bottles, bags to plastic toys. Everywhere we look, we see many plastic products made of polyethylene. Polyethylene is one of the most popular thermoplastic materials available today and is used in many industries to make a variety of products. But, what is polyethylene? What is it made of? How to process polyethylene? Polyethylene is a lightweight and durable thermoplastic with a variable crystal structure. It is one of the most widely used plastics in the world (producing tens of millions of tons of it annually worldwide). Polyethylene is used in various applications for films, pipes, plastic parts and in various industries (packaging, automobile, electricity, etc.). Polyethylene is made from the polymerization of ethylene (or ethene) monomer. The chemical formula is polyethylene (C2H4). Polyethylene is made by the radical addition or polymerization of ethylene (olefin) monomers. (Chemical formula of ethene – C2H4). Ziegler-Nata and metallocene catalysts are used to polymerize polyethylene.

Polyethylene is a family of polyolefin polymers and is classified based on density and branching. The most common types of polyethylene are polyethylenes are divided into the following two categories:

Linear polyethylenes are divided into two different categories:

In addition to the categories mentioned above, polyethylene is also available in other types, such as:

Features Lightweight polyethylene

Lightweight polyethylene or low density polyethylene or LDPE stands for Low Density Poly Ethelene, a semi-hard and semi-transparent polymer. This type of polyethylene has a higher degree of short and long side chain branches than HDPE. Light polyethylene is produced at high pressure in the range of 1000-3000 times and in the temperature range of 80-300 ° C through the process of free radical polymerization. LDPE is made up of 4,000 to 40,000 carbon atoms with many short branches.
Two basic processes used to produce low density polyethylene:

Polymerization is done in two ways and the result of each method is a specific product of polyethylene

The result of high pressure polymerization is the production of lightweight polyethylene or LDPE. But in low pressure polymerization, two types of products are obtained; Heavy Polyethylene (HDPE) and Light Linear Polyethylene (LLDPE).

Advantages and disadvantages of lightweight polyethylene

Lightweight polyethylene has a number of advantages due to its density, molecular weight and the method used to produce it, which justifies its use over similar materials. Benefits such as:

Melting point around 105 to 115 degrees Celsius
Density 0.91 to 0.94 g / 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 shorter period of time
Low cost and cost-effective polymer with good processing capability
Good impact resistance at low temperatures
High resistance to air erosion
Excellent electrical insulation properties
Very low water absorption and moisture
Transparent view in thin sheets

But in addition to its advantages, each product has a series of features that are among its weaknesses and disadvantages. Lightweight polyethylene is no exception to this rule and has disadvantages that include:

High cracking capability against vibration
Low strength, low hardness and low temperature capacity that make it impossible to use to produce products that require high temperature in their process
High permeability to gas, especially carbon dioxide
Low resistance to ultraviolet radiation
Very high flammability
Its connection is not possible through high frequency welding

Applications of lightweight polyethylene

Lightweight polyethylene has special applications in various industries and production of various products due to its advantages, features and properties. Due to the properties of lightweight polyethylene, this material is mostly used in the industries of container production, tankers for transportation and distribution of materials, detergent and sanitary bottles, pipes, plastic packaging for computer parts and various laboratory equipment. The most popular application of low density polyethylene is in the plastic bag industry.

Use of lightweight polyethylene or LDPE in the packaging industry - low cost and affordable price of this type of polyethylene and its good flexibility made LDPE unique ,low density polyethylene can be used in the packaging industry for storage and transport bottles of medicine and tubes of medical devices ( Serum, catheters, etc.), garbage bags, food packaging (frozen, dry, etc.), laminates, etc.
Use of lightweight polyethylene in the pipe and fittings industry - from low density polyethylene or lightweight polyethylene due to its plasticity and low water absorption, as well as resistance to air erosion and high flexibility in the manufacture of water pipes and hoses in the manufacturing industry Pipe products and fittings are used.