polypropylene is a polymer consisting of repeating propylene monomers. PP was first produced in 1951 and since then has become a staple plastic in our everyday lives, used in everything from car bumpers to milk bottles.
The properties of PP are due to the fact that it is a semi-crystalline polymer, unlike ABS which is more amorphous. PP is the lowest density commodity plastic however it is still very tough and flexible. PP's excellent fatigue resistance also means that it retains is shape when subjected to a lot of twisting and bending. The combination of flexibility and fatigue resistance means that PP can even be used to make living hinges (hinges consisting of one thin piece of plastic connecting two parts of the same plastic). PP has excellent chemical resistant and will withstand nearly all fats and organic solvents, with the exception of very strong oxidising agents. PP prints with a smooth finish which is great for low friction parts but also makes it difficult to adhere to other plastics, even with many commonly used glues.
PP requires a printing temperature of between 220°C to 250°C. Bed adhesion is one of the key issues when printing with PP, it will certainly require a heated bed (85-100°C) and probably an enclosure. Printing onto a PP sheet is recommended to maximise adhesion, this may be helped by printing at the higher end of the temperature range. PP is also flammable and burns with a thick black smoke.
PP is a great filament if you need an extremely lightweight, flexible part or living hinge. Printing with PP will definitely expand the creativity of your 3D printing designs and is definitely worth experimenting with once you've mastered printing with easier filaments. Here at Filaments.directory you can select the right PP filament using our constantly updated list of suppliers and our comprehensive search tool!