Category 5 - Polypropylene or PP
Polypropylene is a hard thermoplastic, semi-crystalline in nature, and known for its durability.
It has excellent color-absorbing properties, as its base state of production is transparent. Its lightweight density gives it an advantage in situations where the weight of the product is a primary consideration. Polypropylene, often abbreviated as PP, is the second most widely used plastic after polyethylene (PET).
What is PP plastic used for?
The properties of polypropylene (PP) are suitable for a wide range of industries. Its excellent chemical resistance and high melting point mean that it can withstand steam sterilization methods for effective decontamination of microbes, fungi, and parasites. This makes it an ideal choice for medical applications, medical devices, the food container industry, and those requiring heat resistance.
PP is used in the automotive industry for car dashboards, bumpers, interior and exterior clothing, and interior elements due to its lightweight and flexibility.
As a packaging material, it enjoys a wide range of uses. Its flexible properties have replaced cellophane, metals, and paper due to its lower cost and superior characteristics. In the market, we find it as film and packaging for tobacco, clothing, food, and confectionery.
Another characteristic of the material is its ability to resist liquid absorption. Therefore, it has started to be used in textiles for creating sportswear.
PP is also used for caps, pallets, sheets, bottles, and jars for packaging cleaning products. It is also used for thin-walled containers like packaging for yogurt and disposable cups for hot foods and beverages.
How is PP produced?
Like most types of plastic, polypropylene is made from substances derived from hydrocarbon fuels such as petroleum. First, the propylene monomer is extracted from crude oil as a gas, and this monomer is then subjected to a process called polymerization.
To create different usage qualities, the polypropylene resin must be blended with a variety of plasticizers, stabilizers, and fillers. As needed, after these additives are introduced, this plastic ultimately takes the form of pellets. In this state, polypropylene is sold to various industries to obtain the final form of functional use (e.g. fibers for textiles, molded products, etc.).
History of PP
In 1954, the Italian scientist G. Natta, continuing the work of the German scientist K. Ziegler, succeeded in producing polypropylene with a highly regular structure. The commercialization of polypropylene in Europe and North America began rapidly in 1957, in applications for household tools.
The discovery of this polymer paved the way for the creation of other polymers.
Polypropylene, with a semi-crystalline structure, has better mechanical properties compared to polyethylene. However, the material's density at that time was the lowest of all plastics, and its price was very low. But because it was sensitive to cold and ultraviolet light, it aged quickly. For this reason, its use was reduced to only a few areas. However, the discovery of new light stabilizers and greater cold resistance achieved through propylene+ethylene polymerization brought PP back as one of the most widely used plastic materials of our time.