Polypropylene or PP is a hard, crystalline thermoplastic polymer made from a propylene monomer. Polypropylene or PP is a linear hydrocarbon resin whose structure we will see in this article. Polypropylene is a polymer in the family of polyolefins. Types of polypropylene are one of the most widely used polymers in the industry. In this article from PETROPROVIDERS, we will discuss the types of polypropylene as well as its applications, features, and properties.

Polypropylene and its applications in global industries

Polypropylene applications

Polypropylene applications

Today, polypropylene is used in both plastic and fiber forms. Polypropylene, abbreviated PP, has the lowest density among common polymers. Major manufacturers in the world synthesize this polymer; Because it has a reasonable price and has a variety of uses.

Today, more than 18,000 different grades of PP are produced in the world by more than 350 companies. As mentioned, polypropylene is made from the polymerization of propylene monomer. Ziegler Nata and Metallocene catalysts can be used in their production.

Depending on the spatial arrangement of the chains, PP can be divided into several types depending on the location of the methyl group (CH3):

  1. Atactic PP: The methyl group is randomly located on both sides of the carbon chain.
  2. Iso tactic PP: Methyl groups are all on one side of the carbon chain.
  3. Syndiotactic (Syndio PP): Methyl groups are placed one by one between the two sides of the carbon chain.

Introduction of polypropylene types:

Polypropylene is available in the market in two forms: polypropylene homopolymer and polypropylene copolymer. These polymers are used in various industries and we can use them in various applications. The following is a brief description of them:

PP Homopolymer or PP-H:

This type of polypropylene is used in general applications. Homo polypropylene contains only a propylene monomer and is available in semi-crystalline and solid form. Homo PP-H polypropylene is used in applications such as packaging, textiles, pipes, and automotive industries.

Polypropylene Copolymer or PP Copolymer:

When a monomer other than propylene monomer (usually ethane) is used in the polypropylene structure, we have a polypropylene copolymer. Polypropylene copolymer is divided into two categories. Random polypropylene or PP-R copolymer and PP-B or block polypropylene copolymer.

Random polypropylene copolymer or PP-R

It is produced by the polymerization of ethene and propene, and the amount of ethene is usually used up to a maximum of 6% by mass. The reason for naming the random copolymer is that the arrangement of propene and ethene is random and irregular. This type of polypropylene copolymer is more flexible and more transparent in terms of optical properties. For this reason, this PP-R is used in products that need a great look.

Polypropylene Copolymer Block or PP-B

In this type of copolymer, ethene is also used and usually, its amount is more than the ethene in PP-R and about 5 to 15% is used. The monomers are grouped in the main chain. This arrangement makes the resulting polypropylene harder and less brittle than PP-R, so it is used in industries that require high strength.

In addition to the polypropylene homopolymer and copolymer described above, there is other polypropylene in the industry, such as:

Impact-resistant polypropylene copolymer:

When a PP-R phase (containing 45-45% ethylene) is added to homopropylene, it is called an Impact-resistant copolymer. This type of copolymer is used in applications that need impact resistance, such as home appliances, packaging, parts of the automotive industry, pipes, etc.

Expanded Polypropylene (EPP)

It is a close cell expanded polymer in the form of foam that has a very low density. EPP has a very low weight ratio, excellent impact resistance, and good thermal insulation properties, and is also resistant to water and chemicals. With these features, EPP is used in various industries such as automobiles and packaging.

High Melt Strength Polypropylene (HMS-PP)

Polypropylene normally has low melt strength and is problematic in forming processes that require high melt strength (such as blowing film). Therefore, to solve this problem, polypropylene is made with a branch structure including long branches to increase both the strength of the melt and the ability to develop in the melt phase.

HMS-PP has different grades with different mechanical properties, high thermal stability, and good chemical resistance. HMS-PP is widely used in the food packaging, automotive, and construction industries.

The copolymer and polypropylene homopolymer was described in detail above. In the following, we will tell you the characteristics of different types of polypropylene.

Properties of polypropylene types

Properties of polypropylene

Properties of polypropylene

  • Melting point: Homopolymer: 160 – 165 degrees Celsius
  • Copolymer: 135 – 159 degrees Celsius
  • Density (density): Homopolymer: 0.904 – 0.908 g / cm3
  • Random copolymer: 0.904 – 0.908 g / cm3
  • Impact-resistant copolymer: 0.898 – 0.900 g / cm3
  • Disadvantages and limitations of polypropylene:
  • Low resistance to UV and scratches
  • Fragility at temperatures below -20 ° C
  • The high temperature of use of polypropylene is not too high (90 – 120 degrees)
  • Rapid swelling in aromatic and chlorinated solvents
  • In contact with hot metals does not have high thermal stability
  • Poor printability

Applications of polypropylene

PP uses

PP uses

Packaging Industry:

Polypropylene is a good barrier against steam and moisture, has high strength, and has a good final work finish. It also has a relatively low price. These properties make polypropylene popular in the polymer packaging industry. Polypropylene is used as flexible as well as hard containers. Inflexible packaging, because polypropylene film has excellent optical transparency and vapor and moisture penetration, it has little use.

Consumer goods:

Types of polypropylene are widely used in plastic and everyday household appliances.

The automotive industry:

Due to the relatively low part, suitable mechanical properties, and easy molding, types of polypropylene are widely used in the automotive industry. Battery frame, bumper, fender liner, interior decorations, door decorations, etc.

Fibers and fabrics:

A significant amount of types of polypropylene are used in the fiber and textile industries. High strength, low water penetration, and water vapor make polypropylene a popular polymer in this field.

Summary of review of Different types of polypropylene

Polypropylene is a polymer in the family of polyolefins. Types of polypropylene are one of the most widely used polymers in the industry. In this article, we saw the types of polypropylene and their applications. This material is used to produce a variety of plastics and durable products. In addition, it is used in the automotive and textile industries.

According to the plastics industry, polypropylene is one of the most widely used and basic polymers used in the world and the largest consumer of propylene. The name of this product is polypropylene (PP) and its chemical formula is -CH2-CH (CH3)-n.

Polypropylene is obtained from the polymerization of propylene at relatively mild temperatures and pressures. This reaction takes place in the presence of the famous Ziegler-Nata catalyst. The presence of this catalyst forms an isotactic polymer that can crystallize up to about 90%.

What is your opinion about the types of polypropylene and their application in the industry? Is this substance dangerous for human health and the environment? Can this polymer be easily recycled? In the comments section, you can ask us your questions about this polymer.


Is polypropylene plastic?

Yes! PP is one of the most important and widely used plastic polymers that is used in various industries.

Is the use of polypropylene harmful to human health?

No! It is generally known as a non-toxic polymer; However, it is best not to burn polypropylene.

What are the most important applications of polypropylene in global industries?

PP or polypropylene is used in the manufacture of various plastics, auto parts, and fabrics.

Is it safe to use polypropylene for food packaging?

Yes! It is designated by the FDA as a safe polymer for food packaging.