5 Characteristics of Polypropylene

Polypropylene is a thermoplastic resin used by plastic industries, it is of great importance for those responsible for production and for raw material buyers.

What is polypropylene?

Polypropylene or PP is a thermoplastic polymer produced from the polymerization of propylene or propene gas.

It is a type of plastic that can be molded when subjected to high temperatures, which is why it is classified as thermoplastic.

Characteristics

Polypropylene (PP) is a low density resin . It has very similar properties to polyethylene (PE), but its softening point is higher.

Among the main features are:

  • Low cost
  • Chemical resistance
  • Easy to shape
  • Easy coloring
  • Moderate impact resistance
  • Good thermal stability
  • Not toxic
  • Flexural strength
  • Low moisture absorption

It can be stated that PP has a balance of properties: thermal, chemical and electrical. This makes it a very versatile material.

Among the unique characteristics of PP is its “hinge effect”, which offers the possibility of manufacturing pieces with folds in the material itself, which is used, for example, in glasses cases and folding bottle lids, among others.

Polypropylene has few disadvantages, but we can highlight the low resistance of the material to sudden changes in climate, which can, for example, cause stains and loss of properties when exposed to the sun.

How to solve this problem? The most used solution for this is the polymer additive with antioxidant and ultraviolet stabilizer to delay wear.

Properties

  • Resistance: this is one of the most important properties of the polymer, having resistance not only to impacts or pressures, but also to chemical substances, remaining a quality product against oils and solvents. Polypropylene also has heat resistance (but limited).
  • It is a 100% recyclable product, it does not release harmful substances in case of combustion.
  • Easy storage, cutting, slotting, processing and washing with water.
  • Possibility of ultrasonic welding, stapling, drilling.
  • Corona treatment: Corona treatment is carried out using electrical discharges that stabilize the physical and chemical effects of the respective polypropylene surfaces.
  • The release of electrons thus creates an oxidation reaction in the sheet that increases the energy of the polypropylene surface and provides better printing quality.
  • Profitability: due to the competitiveness of the current market, polypropylene is one of the most profitable plastics, having the highest annual growth rate in the world, due to its great properties, from its resistance to its wide versatility of application and use.

Main applications

This compound has many applications in people’s daily lives. Some of these applications are:

  • Flexible packaging
  • Grain and fertilizer bags
  • Plastic chairs
  • Toys
  • plastic cups
  • Home appliances
  • Soft drink tapas
  • Injection syringes
  • auto parts
  • Tupperware

How can it be processed?

The versatility of polypropylene is also present in the ways in which it can be processed. They are they:

  • Injection
  • film extrusion
  • Filament extrusion
  • Thermoforming
  • Blew it

Furthermore, polypropylene (PP) can be said to be an improved polyethylene (PE), as it can replace it in applications where the exceptional chemical resistance of PE is not as necessary or a priority.

Polypropylene recycling

Polypropylene can be recycled with some ease. Each plastic produced from the polymerization of propylene or propylene gas has a seal or identification mark on its products, which can be easily recognized by the triangular symbol (which refers to recyclable products), with the number five inside and with the nomenclature “PP” written.

How does it work?

In summary, this is the basic standard process for PP recycling:

  • Separation of material according to its use.
  • Grinding to facilitate the fusion of plastic with uniformity.
  • Material ready to receive dyes of various types.
  • The polypropylene is injected into molds that give it a new shape.

Benefits

The polypropylene recycling process provides several benefits (including economic) to the company that carries it out:

  • Reduction of costs related to raw materials.
  • Promotes the preservation of the environment.
  • The material that already has the versatility of applications is now reusable (even more efficient).
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