Polypropylene, without additives is white to colourless, similar to polyethylene but more rigid. Good mechanical characteristics even at high temperatures. High fatigue strength, low density 0.90 g/cubic centimetre, good electrical characteristics, good chemical resistance and good mechanical characteristics make propylene plastic usable in a number of different contexts, especially were high demands are set on temperature resistance and mechanical stability. Propylene plastic is often in copolymers with ethylene, which results in better low-temperature characteristics (especially impact strength). The same effect is achieved by mixing in small amounts of rubber, e.g. EPDM in the homopolymer. PP is readily broken down by UV radiation and must be stabilised for outdoor use.
- High fatigue strength
- More rigid than HDPE. There are filled and reinforced qualities with e.g. chalk, talc and fibre glass that compete with ABS
- Maintains its mechanical characteristics better at high temperatures than HDPE
- Low density 900-910 kg/m3
- Chemical resistance similar to that of polyethylene, but not the same tendency to stress crack formation
- Mechanical and electrical characteristics are also retained in water
- Becomes brittle below -20ºC
- Broken down by UV radiation if it is not stabilised
- Is attacked by oxidizing acids
- Heat stability is reduced in contact with copper
- Easier to glue together with other materials, such as wood and aluminium than with itself
Fan propellers, car grills, instrument panels, chassis, bottles, containers, pipes, wheels, door handles, casings for kitchen appliances and hairdryers, rope, medicine and cosmetics packaging, electrical insulation details, toolboxes, etc.
Available as homopolymers and copolymers. The copolymer PP-PE has better impact strength in cold than the homopolymer PP. PP is suitable for injection moulding, thermoforming, blow moulding and extrusion and can be stamped, welded, foiled and vacuum-metallised.