Polypropylene (PP): Definition, Types, and Characteristics

Polypropylene (PP) is one of the materials produced by the chemical industry for various purposes, including plastic production.

Polypropylene is also one of the materials found in various products, such as packages, car components, clothes, and many more.

This article discusses polypropylene, how to make it, its characteristics, and so on. Thus, read the article until the end!

What Is Polypropylene (PP)?

Polypropylene (PP) is a thermoplastic linear hydrocarbon polymer resin that is a bit rigid and resistant to chemicals and electricity at high temperatures.

Since PP is a thermoplastic, it can be soft at high temperatures and hardens at low temperatures. Due to this property, thermoplastic, including polypropylene can be recycled. Besides, PP is considered safe for health, making it suitable for producing furniture, medical tools, and packages.

Polypropylene is a material used to manufacture various products daily, such as plastic and fiber thermoplastic. Moreover, polypropylene is considered the second-largest plastic resin in the world based on production volume, and the first is polyethylene (PE).

According to Statista, in 2018, the global manufacturing of polypropylene reached 56 million metric tons, and in 2026, the production is forecasted to reach 88 million metric tons.

PP, made of propene monomer, was initially found in the mid-1950s by Italian scientists. It is considered stronger than PE plastic, especially its durability at high temperatures.

The Characteristics of Polypropylene

As mentioned before, polypropylene or pp is a thermoplastic that can melt at high temperatures and harden at normal or low temperatures. As a result, the product made of PP can be shaped and recycled.

Furthermore, PP is resistant to acids and bases, making it suitable for packing liquid products like cleaning liquids.

Additionally, PP has the elasticity to a limited deflection range. This material also experiences initial distortion during the deformation process, making it tough and not easily broken even when bent.

Moreover, polypropylene is resistant to high currents so it is suitable for manufacturing electrical components and electronics.

Lastly, PP has the characteristic of opaque original color. Then, PP products can be processed to be transparent when sold or used.

How Polypropylene Is Made?

Polypropylene (PP) is made by polymerizing propene gas with a catalyst system such as a metallocene or Ziegler-Natta catalyst.

The polymerization parameters, such as pressure, temperature, and concentration of reactants are determined based on the desired polymer grade. Some production methods might undergo gas-phase or liquid-phase processes.

Gas-Phase Process

In this process, the reaction occurs in a fluidized bed reactor at a temperature of 70°C to 100°C and a pressure of 1-20 atm.
Hydrogen and propane are carried through the catalytic bed.
Propane is converted into polypropylene in the form of a fine powder, then separated from unreacted propane and hydrogen using a cyclone separator.
The fine powder will be made into pellets and ready for further use.

Spheripol Process

This phase uses propane, ethylene, and hydrogen.
The reaction occurs by suspending the catalyst and monomer units in an inert solvent, such as a light hydrocarbon.
The liquid monomer and catalyst are pumped into one or two vertically stirred gas-phase reactors to proceed to the polymerization process.
When polymerization is complete, the mixture of polymer powder and monomer is poured into a dip tube.
The unreacted monomer is recycled to the gas-phase reactor and the polymer is stored for future use.

Types of Polypropylene

There are two types of commonly used polypropylene, which are homopolymer and copolymer. Below is the completed explanation:

1. Polypropylene Copolymer

Polypropylene copolymer is a polymerization product of propene and ethane. It is also divided into two: random copolymer and block copolymer.

The random copolymer has 6% of ethane and the block copolymer has 5–15% of ethane. Copolymer has a darker color compared to homopolymer. It is also stronger and thicker than a homopolymer.

2. Polypropylene Homopolymer

Polypropylene homopolymer is frequently used for industry and manufacturing purposes. It is in semi-crystalline solid and contains propylene monomer.

Typically, homopolymer is utilized to produce automotive components, packages, medical tools, and clothes. Because it has less ethane, it is more transparent compared to the copolymer.

The Advantages of Polypropylene

Polypropylene (PP) is utilized to create various products, from medical assets to vehicle components. PP also has several advantages, such as:

Accessible and cost-effective.
Acids and bases resistance.
Great electric insulator.
Resistant to moisture and water absorption so it does not rot easily.
Flexible enough, but is still strong.
No harmful emissions, hazardous waste, halogen, or fluorocarbon during the manufacturing process.
Needs fewer resources than other manufacturing products, such as canvas and paper.
Fatigue and impact resistance.
Lightweight.
No cancer-causing effect.
Less waste and recyclable.
No hazardous substances, making it safe to throw or burn.

Those are the information about polypropylene (PP) you should know. As one of the massively produced industrial materials, you should choose the top-notch polypropylene provider.

In this regard, Chandra Asri Group as a chemical solution company provides polypropylene under the Trilene trademark. Trilene is produced strictly under a deep quality assurance process, resulting in a high-quality PP product.

Chandra Asri Group sells Trilene in 25 kg packages and provides polypropylene homopolymer, random copolymer, impact copolymer, and terpolymer.

So, ensure that you always use the top-notch chemicals from trustworthy providers like Chandra Asri Group!