What are the differences between Polypropylene and Polyurethane?
Polypropylene (PP) is the second most produced plastic in the world, after polyethylene (PU).
They are both versatile and durable, and they are used in a wide variety of applications. Understanding the differences between PP and PU is important because it allows you to choose the right material for the job.
1. Properties of polypropylene
1.1. Physical properties
Polypropylene (PP) is a thermoplastic polymer that is known for its lightweight, strength, flexibility, and heat resistance.
Appearance: PP is a white, translucent solid.
Lightweight: With a density of roughly 0.9 g/cm3, PP is one of the lightest plastics available. This makes it perfect for applications requiring weight reduction, such as automotive and aerospace.
Strong: PP is a tough and long-lasting polymer that resists impact, abrasion, and fatigue. It has equivalent tensile strength to steel at up to 48 MPa. As a result, it is perfect for applications requiring strength and durability, such as packaging and construction.
Flexible: PP is a versatile material that may be easily molded into an array of shapes. This makes it perfect for applications that require complex shapes, such as medical and consumer items.
Heat resistant: With a melting point of 173°C (343°F), PP is one of the most heat-resistant plastics on the market. Therefore, it is appropriate for applications involving high temperatures, such as food processing and automotive applications.
1.2. Chemical properties
PP is a non-polar polymer, which means that it is not very reactive with other chemicals. It is also non-toxic and does not support the growth of bacteria. This makes it highly resistant to a wide range of chemicals, including:
Acids: hydrochloric acid, sulfuric acid, nitric acid, acetic acid
Bases: sodium hydroxide, potassium hydroxide, ammonia
Solvents: water, alcohol, gasoline, oil
The only chemicals that are known to dissolve PP are strong oxidizing agents, such as concentrated sulfuric acid and nitric acid.
1.3. Processing properties
PP is a breeze to mold and shape. You can turn it into all sorts of things, from films and sheets to fibers and foams. This makes it a great choice for a variety of manufacturing processes, such as injection molding, blow molding, and thermoforming.