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Last edited 15 Apr 2019
Polypropylene (PP, also known as polypropene or polymerised propene) is a type of thermoplastic polymer resin that has similar qualities to polyethylene (PE) but is slightly harder and has better resistance to heat and organic solvents. After PE, polypropylene is the second-most widely produced commodity plastic with a global market (2013) of around 55 million tonnes.
A member of the polyolefin family of resins, PP can be injection moulded and extruded into many shapes and products such as cups, cutlery, containers, housewares and car parts e.g batteries. It is also spun into fibres for inclusion in industrial and domestic textiles, including for clothing.
- Lightweight, tough and flexible
- Heat resistant (high melting point (around 160°C) – used in microwaves, dishwashers, food containers
- Chemically inert
- Impact and freeze-resistant
- High shatter resistance
- Low moisture absorption
- Mould resistant
- Low density allows lower-weight mouldings to be made
- Resistant to fats and organic solvents
- Accepts colour and dye without degrading
- Reasonably inexpensive
- Does not contain BPA (bisphenol A - which some claim can leach into food products)
- Fatigue resistance – allows use as a plastic hinge
- It can float in water
 Typical applications
It has a large number of end-use applications in the construction industry due to the wide range of grades available and the use of additives to modify properties:
- PP fibres are added to concrete to increase strength and reduce cracking and spalling
- Non-woven fabrics for ground stabilisation
- Roofing membranes (waterproofing top-layer in single-ply systems)
- Reinforcement in construction and road paving
- Electrical cable insulation (alternative to PVC)
- Piping systems
- Carpets, rugs and upholstery
- Medical and laboratory equipment
- Reusable containers
- Plastic machine parts
- Industrial rope and cordage
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