The material. Polypropylene, or PP, first produced commercially in 1958, is the younger brother of polyethylene, a very similar molecule with similar price, processing methods, and application. Like PE it is produced in very large quantities (more than 30 million tons per year in 2000), growing at nearly 10% per year, and like PE its molecule lengths and side branches can be tailored by clever catalysis, giving precise control of impact strength, and of the properties that influence molding and drawing. In its pure form polypropylene is flammable and degrades in sunlight. Fire retardants make it slow to burn and stabilizers give it extreme stability, both to UV radiation and to fresh and saltwater and most aqueous solutions.
Composition
(CH2-CH(CHs))n
|
General properties
|
Polypropylene is widely used in household products.
Ecoproperties: material
|
Annual world production |
43 X 106 |
– 44 X 106 |
tonne/yr |
|
Reserves |
*1.2 X 109 |
– 1.3 X 109 |
tonne |
|
Embodied energy, primary production |
85 |
– 1.10 |
MJ/kg |
|
CO2 footprint, primary production |
2.6 |
– 2.8 |
kg/kg |
|
Water usage |
*50 |
– 150 |
l/kg |
|
Ecoproperties: processing |
|||
|
Polymer molding energy |
*8.2 |
– 9 |
MJ/kg |
|
Polymer molding CO2 footprint |
*0.65 |
– 0.72 |
kg/kg |
|
Polymer extrusion energy |
*3.2 |
– 3.5 |
MJ/kg |
|
Polymer extrusion CO2 footprint |
*0.25 |
– 0.28 |
kg/kg |
|
Recycling |
|||
|
Embodied energy, recycling |
36 |
– 44 |
MJ/kg |
|
CO2 footprint, recycling |
1.1 |
– 1.2 |
kg/kg |
|
Recycle fraction in current supply Recycle mark |
5.1 5 PP |
– 6 |
% |
Typical uses. Ropes, general polymer engineering, automobile air ducting, parcel shelving and air-cleaners, garden furniture, washing machine tank, wet-cell battery cases, pipes and pipe fittings, beer bottle crates, chair shells, capacitor dielectrics, cable insulation, kitchen kettles, car bumpers, shatter proof glasses, crates, suitcases, artificial turf, thermal underwear.
