Polypropylene (PP)
A lightweight, chemically resistant thermoplastic with a higher temperature ceiling than HDPE and a unique living hinge ability.
About Polypropylene
Polypropylene is a rigid product highly resistant to most chemicals. It is ideal for fabrication as it also has excellent impact strength and is easily welded, fabricated and machined.
PP resists flex fatigue better than any other common plastic, which is what makes a living hinge possible. It is food safe, holds its properties at higher temperatures than polyethylene, and is the lightest of the common engineering plastics. We stock it in natural, grey, black and white.
We weld PP into chemical tanks, bunds and laboratory fittings, and cut sheet to any size you need.
Key Properties
- Polymer family
- Polypropylene, PP, homopolymer or copolymer
- Density
- Around 0.90 g/cm3 (the lightest common plastic)
- Max service temperature
- Approximately 100 C continuous
- Tensile strength
- Around 30 to 40 MPa
- Common thicknesses
- 2, 3, 4, 5, 6, 8, 10, 12, 15, 20 mm
- Notable property
- Forms a fatigue resistant living hinge
What makes Polypropylene useful
Excellent chemical resistance, broader than HDPE in some chemicals
Higher temperature limit than HDPE, suitable for hot water and steam contact
Lowest density of all common plastics, floats easily and weighs very little
Forms a fatigue resistant living hinge for clamshell and folding parts
Food contact certified grades widely available
Heat weldable for tank and ducting fabrication
Common uses for Polypropylene
Chemical and acid storage tanks
Laboratory benches and fume hoods
Battery boxes and battery cases
Hospital and medical equipment housings
Folding cutting mats and chopping boards (hot water tolerant)
Auto interior trim and door pockets
Living hinge parts (Tic Tac box, shampoo cap)
Sterilisable medical containers
Pipework and pipe fittings
Outdoor furniture frames
Reusable food containers and crates
Twin wall corrugated sheet (Coreflute) for signs
The honest picture
Every material has trade offs. Here is where Polypropylene shines and where it falls short.
Pros
Handles higher temperatures than HDPE, opening up hot water and steam applications
Resists more chemicals than most plastics, including many acids that attack HDPE
Very light, with the lowest density of any commodity plastic
Living hinge capability is unique and enables one piece folding designs
Food and medical contact certified grades are readily available
Limitations
Brittle in cold weather, becoming much weaker below around 0 C
Not UV stable in standard grades, needs UV stabiliser for outdoor service
Cannot be solvent welded, only heat welded or mechanically fastened
Paints and adhesives do not bond without surface pretreatment
Polypropylene versus the alternatives
HDPE
Polypropylene tolerates higher temperatures (around 100 C versus 80 C for HDPE) and resists some chemicals HDPE does not. HDPE is tougher in the cold and more stable outdoors. Use PP for hot water and lab work, HDPE for outdoor and cold applications.
PVC
Polypropylene handles much higher temperatures and is easier to recycle. PVC is flame retardant, which PP is not. Use PP for chemical service that gets hot, PVC for flame retardant requirements at moderate temperatures.
ABS
ABS is stiffer, paints better and machines like wood, but is not chemically resistant and is not food safe. PP is the choice for chemical service and food contact, ABS for visible product housings.
How we work with Polypropylene
The fabrication methods best suited to Polypropylene, and what we do with them in our Moonah workshop.
Polypropylene FAQs
Need Polypropylene for Your Project?
Talk to our team about how we can cut, fabricate or repair Polypropylene for you. Free quotes, expert advice and Australia wide delivery from our Moonah workshop.