Polypropylene — PP — is the plastic of living hinges, chemical tanks and lightweight parts. It is one of the lightest common plastics, resists fatigue beautifully, and stands up to a wide range of chemicals. For cost-sensitive, corrosion-resistant applications, PP is often the smart choice.
What PP is
Polypropylene is a semi-crystalline thermoplastic made from propylene. It sits between commodity plastics like polyethylene and engineering plastics like nylon: cheaper and lighter than the engineering grades, but tougher and more heat-resistant than many people expect.
The properties that matter
| Density | Very low — one of the lightest plastics |
| Chemical resistance | Excellent against acids, bases and solvents |
| Fatigue resistance | Outstanding — the “living hinge” material |
| Water absorption | Essentially zero |
| Temperature | Up to approx. 90 °C |
| Cost | Low — excellent value |
The famous living hinge
Few materials can flex back and forth millions of times without cracking. PP can, which is why it is used for integral hinges on flip-top caps, storage boxes and packaging. That fatigue resistance also makes PP a good choice for parts that must endure repeated movement.
Where PP is used
- Chemical tanks and vessels — welded PP for corrosive service.
- Pipe and fittings — laboratory and industrial drainage.
- Food containers and closures — food-safe grades.
- Machined parts — spacers, washers and covers.
- Automotive and appliances — lightweight structural and trim parts.
Where it falls short
PP is soft, has low stiffness, and is very sensitive to UV unless stabilised. It also becomes brittle at low temperatures, so cold-service parts need care. But for chemical resistance, light weight and cost, PP is hard to beat.
Get PP in the form you need
We supply PP sheets and rods, plus welded fabrications and machined parts. See the full PP specification or ask for a quote.