Polypropylene (PP)

Materials › Polypropylene (PP)

Density below 1 and low cost: PP is the choice when the part does not need to be stiff but needs to be plentiful and light. It offers good resistance to many acids, bases and aqueous solutions, but compatibility has to be checked against substance, concentration, temperature and contact time, with particular attention to oxidisers and solvents. Here, though, the axis is not «how much filler» but «which filler»: talc and glass fibre do two different things, and one of the two makes the part worse if chosen for the wrong reason.

Talc stiffens and cuts cost, but it does not make the part stronger: for that you need glass. Strength does not appear below, and it is not an oversight: on the datasheets in the archive PP is reported now at yield, now at break, and the two do not add up — neither reaches a sufficient sample across all three levels. PP also shrinks a lot and anisotropically, and without additives it does not survive sunlight: for outdoor use, ask for a UV-stabilised grade.

Each row is the median of a selection of manufacturers’ datasheets held in our archive, with the property, the standard and the number of grades stated next to the value. These figures describe the sample: they serve to compare the levels with one another, not to size a part, and they are not a guaranteed material specification. For that you need the datasheet of the chosen grade, which we supply on request.

Where a level shows no value, the documented sample was not sufficient: we prefer to remove the figure rather than publish one that does not hold. HDT and impact strength are deliberately absent, because datasheets often do not state the test condition — whether HDT is at 1.8 or 0.45 MPa, whether the impact specimen is notched — and values collected under different conditions cannot be compared.