Polystyrene is a widely used plastic polymer in various industries, and its types and applications are examined in detail. In the following, we will examine some types of polystyrene and its uses.
Types of polystyrene
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Polyethylene raw materials are often produced from crude oil. Polyethylene is a thermoplastic polymer obtained from ethylene monomer. The steps to prepare these materials are:
Separation of Crude Oil: Crude oil is extracted from miners or oil extraction sites.
Crude oil cracking: In the continuation of the process of preparing polyethylene raw materials, crude oil is broken into smaller pieces. One of these products is the polymerization of ethylene.
Production of ethylene monomer: The ethylene product obtained from the cracking step is converted into ethylene monomer.
Polymerization: Ethylene monomer is converted into polyethylene in the polymerization process under certain conditions. This process involves connecting thousands of ethylene molecules together in the form of long polymer chains.
Production of polyethylene parts: After the formation of polyethylene, it can be converted into various parts such as beams, sheets or polyethylene bags.
Please note that these descriptions are approximate and more details may be available at each stage.
Polyethylene raw materials can be used to produce different products and with different applications. These products can be used in various industries including packaging, automotive, clothing, electronics, construction and many others. Examples of some of these products are as follows:
Plastic bags: Shopping bags, garbage bags and many other plastic bags are produced from polyethylene raw materials.
Pipes and fittings: Polyethylene pipes and fittings are used in water, gas and sewage systems.
Containers and bottles: Bottles of water, soft drinks, oil, liquid soap and various chemicals are also usually produced from polyethylene raw materials.
Car parts: Some internal and external parts of cars may also be produced from polyethylene.
Plastic boards: construction boards, advertising and exhibition boards and other similar applications are made of polyethylene.
Thermal tools: some thermal tools such as cold and hot bags, thermal bottles, etc. are produced from polyethylene.
Shoes and clothes: Some shoes, clothes and clothes are made of polyethylene.
Electronic components: some electronic components and electrical insulation may also be produced from polyethylene.
Food packaging: Some food packaging, such as plastic films and leak boxes for tea, coffee, etc., are made of polyethylene.
Cosmetic products: Some bottles, tubes and packaging of cosmetic products are made of polyethylene.
These are just a few examples of products that can be produced from polyethylene raw materials. Since polyethylene has various properties, including properties such as flexibility, chemical resistance and insulation, it is used in the production of various products.
Today, polyethylene pipes and plastic have many applications in various industries. The variety of these uses is so great that it is impossible to imagine today’s life without this material. Products produced with heavy and light polyethylene have created a deep transformation in many industrial, sanitary and domestic functions. Of course, we should look for this evolution in the special capabilities of this material. With this introduction, in the rest of this article, we are going to talk about how much this product is and its importance. So, join us as we rediscover this material by addressing the following topics:
1- Compositions and the most important types of polyethylene
2- The most important advantages and applications of light and heavy polyethylene
3- Plastic and polyethylene pipe
4- A look at the factors affecting the price of polyethylene products in the market
Polyethylene: (Polyethylene PE) or polythene (Polythene or Polyethene) should be considered a variable crystalline thermoplastic polymer that is very versatile. This material is made of ethylene molecules, which gives it the ability to be thermally molded into different shapes and sizes. Some sources consider polyethylene types to be the most commonly used plastics in the world. Of course, we must remember that some modified polyethylene plastics, such as the cross grades of this product, have thermostat properties; It means that they are not malleable and malleable.
It may be hard to believe that for the first time in 1898, a German chemist accidentally discovered polyethylene while trying to make a more stable version of diazomethane. This material was later synthesized for industrial use in 1933, and about six years later, the mass production of low-density polyethylene began. However, in the 1950s, catalysts were discovered that improved the polymerization aspect of polyethylene plastic production. This process accelerated the production of high density polyethylene over the next twenty years and beyond to produce the product we have available today.
Polyethylenes often have a linear structure. This material consists of hydrocarbon chains, the most important component of which is the ethylene molecule, which has 2 carbon atoms and 4 hydrogen atoms. Therefore, we can write the general formula of polyethylene as (C2H4)n; That is, when the macromolecules of ethylene are combined in the form of straight or branched chains, they make polyethylene. In fact, the molecules of this substance are not covalently connected, but in a crystalline structure and connected by intermolecular forces.
Polyethylene is made by the polymerization process in the presence of a catalyst; In this process, hydrocarbon fuels are distilled into lighter groups called monomers. Here, we cannot say in detail what the components of the specialized process of polyethylene pipe production are, but we will suffice to say that the higher the crystallinity of the polymer, the higher its density and chemical stability. In fact, the polymerization process is usually carried out using a catalytic reactor.
They produce polyethylene with different grades and formulations, each of which has its own properties. In fact, its different types are determined based on the density of the plastic and the degree of branching in their structure. The type of branching and the degree of branching have a direct effect on the mechanical properties of plastic. As a result, we can categorize the most common types of polyethylene in the following categories:
1- branched
2- linear
3- cross
Perhaps the most widely used type of this material is branched light or low density polyethylene (LDPE) and linear type heavy or high density polyethylene (HDPE). Both types are made from the same raw material; It means ethylene gas. Despite this, their production process, properties and applications are very different from each other. According to the above division, we can consider the subtypes of polyethylene plastic as the following:
1- Ultra low molecular weight polyethylene (ULMWPE)
2- High Density Mesh (HDXLPE)
3- High molecular weight (HMWPE)
4- cross (XLPE)
5- medium density (MDPE)
6- Linear Low Density (LLDPE)
7- Chlorinated polyethylene (CPE)
The main difference between heavy and light polyethylene should be found in their degree of crystallinity. Its approximate amount is 35% in light type and 80% in heavy type. In the following, we will examine these two types of polyethylene more.
This type of polyethylene has good flexibility, chemical resistance and impact resistance. In fact, it is a semi-hard thermoplastic Polyethylene and a good insulator of electricity. These conditions make light polyethylene mainly suitable for making plastic bags. With high flexibility, this material has low tensile strength, and if we want to compare it with heavy polyethylene, it has less thermal resistance and is highly flammable.
Flexibility: With its branched molecular structure, LDPE Polyethylene is more flexible than heavy polyethylene, which makes it a suitable choice for applications such as packaging and plastic bags.
Resistance to moisture: Light polyethylene is resistant to moisture, which prevents destruction and loss of shape in contact with water. As a result, light polyethylene plastic is suitable for applications where preventing moisture penetration is important.
Clarity: Light type is clearer than heavy type. Therefore, this material is used to make containers or plastic bottles, whose content is important to be seen.
Ease of production processes: LDPE is easier to process than HDPE and therefore it is cheaper to produce.
Recyclability: types of heavy and light polyethylene can be easily recycled, and this feature contributes to a more sustainable production process.
This material is mainly composed of linear molecules held together by intermolecular forces. Not having side branches in this polyethylene makes the chains to be compressed well. This high density results in a product that is relatively stiff, making it suitable for applications such as cutting boards, juice containers, plastic lumber, and toys. HDPE Polyethylene has good chemical resistance and maintains its strength at very low temperatures. The most important features of this material are as follows.
Strength: The linear molecular structure makes heavy polyethylene a suitable material for bearing pressure and weight, which is suitable for applications such as pipes, fuel tanks and industrial containers.
Chemical resistance: HDPE Polyethylene is resistant to various chemicals, including acids, bases and organic solvents. As a result, it can be a suitable material for making containers for storing corrosive substances such as detergents and cleaners.
Temperature tolerance: heavy polyethylene can withstand from -100 to 120 degrees Celsius; As a result, its use is more in harsh environments.
UV resistance: HDPE is resistant to ultraviolet (UV) radiation, which prevents its degradation and brittleness when exposed to sunlight.
These pipes are usually made of chemically cross-linked polyethylene, abbreviated as PEX or XPE. As a result, the polyethylene pipe is resistant to hydrolysis and strong electrical insulation and has good wear resistance. The main use of this material is to make piping systems, radiant heating and cooling. Also, this product is used for domestic water piping and as insulation for high pressure electric cables.
What is the use of polyethylene?
Packaging industries: types of polyethylene with the ability to protect products and food against air, humidity and chemical damage have many applications in packaging industries. For example, light polyethylene is used to produce packaging films, laminates, garbage bags, grocery bags, and containers.
Construction industry: Products made with heavy and light polyethylene are used in the construction industry as moisture insulation and vapor barrier, cooling and heating pipes, connections and insulation of wires and cables.
Agriculture: The use of polyethylene in agriculture is mainly for making buckets, mulch, greenhouse covers, silage bags and irrigation pipes.
Various industries: Heavy polyethylene tanks and pipes are used for industrial applications such as storage, transportation and processing of chemicals in factories and vehicle components. Tension cables, household appliances, geomembranes, ice trays, industrial fabrics and bulletproof vests can also be considered as the most important uses of this material.
Consumer goods: Polyethylene plastic is widely used in the field of making consumer goods such as toys, personal care products, bottles, fruit juice and milk containers, and garbage containers due to its low price and easy molding in different shapes and sizes.
Medicine: In medical applications, various products such as polyethylene bags and tubes are used to store and transfer medical liquids and gases. The non-porous nature of this material and its resistance to pollution have made it used to make cutters and other medical products.
Textiles: polyethylene fibers are used for various applications in the textile field; including: clothing, upholstery, rope, fishing nets, agricultural nets and carpets.
Advertising industry: Polyethylene types are used in banners, posters and signs due to the possibility of easy printing on them.
Raw material recycling industry: We can recycle all types of this product and use it in many applications such as producing plastic lumber, garden furniture and other outdoor products.
The properties of materials such as polyethylene plastic make it suitable for recycling; Because we can melt it and turn it into another product. On the other hand, its resistance to chemical pollution and liquid absorption means that the recycled product will not contain many impurities. Usually recycling number 2 is used for HDPE and number 4 for LDPE. Many recycling facilities can process both types for reuse. Of course, despite all this, we cannot consider this substance as biodegradable and in this sense it is a little far from the goals of sustainable development.
The price of products such as polyethylene pipe is mainly dependent on the following factors.
Crude oil price: Polyethylene plastic is made from ethylene, which is a raw material derived from crude oil. As a result, crude oil price changes can directly affect the price of polyethylene.
Supply and demand conditions: If the demand for polyethylene in the market is high and its supply is limited, the price of this product may increase and vice versa.
Production costs: The direct and indirect costs of producing various types of polyethylene, including the costs of energy, labor and raw materials, play a role in determining its price.
Exchange rate fluctuations: Exchange rate changes in the countries that import polyethylene products can affect the price conditions of polyethylene plastic. An increase in the value of the local currency may lead to a decrease in the price of polyethylene in the global market.
Laws and regulations: Some changes in laws and regulations related to the production and export of polyethylene can also affect its price. For example, an increase in taxes or tariffs can lead to an increase in the price of polyethylene.
final word
Types of light and heavy polyethylene should be considered as the most widely used materials in the world, each of which has special properties and applications. Polyethylene plastic is used in various industries with its molecular structures, mechanical properties, recyclability and strength. Materials such as bags, tanks and polyethylene pipes have a high chemical resistance against acids and alkalis. But it is not only the use of polyethylene that has made it popular, but another aspect of it should be sought in the advantages of this product as follows:
1- low cost
2- adaptation
3- low weight
4- Moisture resistance
5- Strength
6- insulation
7- Possibility of printing
8- Low environmental impact
Source
https://designetics.com/blog/what-are-polyethylene-plastics-types-differences
