Polyethylene vs Polypropylene – which plastic is best?
Polyethylene and polypropylene are two of the most common engineering plastics on the market. Since the materials share many similarities, it is common to compare polyethylene vs polypropylene when developing a new product or optimising an existing component.
Although both polyethylene plastic (PE plastic) and polypropylene plastic (PP plastic) offer high chemical resistance, low weight and a long lifespan, there are important differences that affect which material is the best choice. The right plastic depends, amongst other things, on load, temperature, environment and the requirements placed on the finished product.
What is polyethylene (PE)?
Polyethylene (PE) is one of the world's most widely used plastics and is valued for its high impact resistance, low weight and very good chemical resistance. The material is also moisture-resistant and has low friction, making it suitable for many different industrial applications.
Common properties of polyethylene are:
- High impact resistance, even at low temperatures
- Very good chemical and moisture resistance
- Low weight
- Good abrasion resistance
- Low friction and good glide properties
Polyethylene is often used for slide rails, wear parts, tanks, containers, conveyors and other components where wear resistance and chemical resistance are important properties.
What is polypropylene (PP)?
Polypropylene copolymer (PP) is an engineering plastic characterised by high rigidity, low weight and good temperature resistance. The material is often used when components need to retain their shape even at higher temperatures or are exposed to chemicals over a long period.
Common characteristics of polypropylene are:
- High stiffness and dimensional stability.
- Good chemical resistance.
- Low density and weight.
- Good fatigue strength.
- High temperature resistance compared to PE plastic.
PP plastic is used, among other things, in the chemical industry, the food industry, medical technology and for technical components where rigidity and dimensional stability are important.
Skildifferences between polyethylene and polypropylene
Both polyethylene and polypropylene have many similar properties, but they differ in several important areas:
| Property | Polyethylene (PE) | Polypropylene (PP) |
| Stiffness | Lower | Higher |
| impact toughness | Very high | High |
| Temperature resistance | God | Very nice |
| Chemical resistance | Very high | Very high |
| Weight | Very low | Very low |
| Machinability | Single | Single |
When is polyethylene best suited?
Polyethylene is often the best choice when the component is exposed to impacts, abrasion or damp environments.
Common areas of use are:
- Slide and wear parts
- Conveyor belt and guides
- Tanks and containers
- Machine components
- Food-grade components
- Components in corrosive environments
The material's high impact strength means it retains its properties even at low temperatures, making PE plastic suitable for many demanding industrial environments.
When is polypropylene best suited?
Polypropylene is used when high rigidity and temperature resistance are more important than maximum impact strength.
PP plastic is a common choice for:
- Chemical tanks
- Pipework
- Process equipment
- Technical industrial components
- Medical devices
- Food applications
The material's good dimensional stability makes it exceptionally well-suited for components that need to maintain their shape even at higher temperatures.
How do you choose the right material?
There is rarely one material that is best in all situations. The choice between polyethylene and polypropylene should always be based on the product's area of application and the requirements placed on the component.
Some questions to base this on are:
- What mechanical load will the component be subjected to?
- What temperatures must the material withstand?
- Is there any contact with chemicals or moisture?
- Is low weight or high stiffness most important?
- What are the requirements regarding lifespan, processing and cost?
By making an overall assessment, it becomes easier to choose the right one.
Do you need help choosing the right engineering plastic?
Choosing the right plastic material requires knowledge of both the properties of the materials and the application area of the product. At Carlsson & Möller, you get help through the entire process – from material value and design to manufacturing.
With a board range, extensive experience and high material expertise, Carlsson & Möller helps you find the solution that provides the best function, service life and economy.
Would you like to discuss which material is best suited for your application? Get in touch and we will help you find the right solution!
