#PP

Polypropylene (PP) is a semicrystalline thermoplastic polymer characterized by a high breaking load, low density, good chemical, thermal and abrasion resistance. It is an easy to process product and relatively cheap compared to other polymers. Due to its high crystallinity, polypropylene is usually presented opaque white or colored with pigments. Polypropylene can degrade at the molecular level if exposed to UV radiation, through a degradation mechanism that determines the formation of free radicals that react with the oxygen in the air, breaking the polypropylene chain. From a macroscopic point of view, degraded PP shows cracks that increase in extension and depth as the exposure time advances. For outdoor applications, UV stabilizing or absorbing additives must therefore be used in polypropylene; carbon black also has a good effectiveness in stabilizing polypropylene for exteriors.

The PP can be divided into three main groups:

• PP OMO (H-PP): homopolymer polypropylene. It has a slightly higher density than the copolymer variant (0.905 and 0.897 g / cm3 respectively) and has greater elastic modulus, higher hardness and greater maximum effort, but also a low resilience at low temperature, due to its high crystallinity. Furthermore, the optical transparency of the homopolymer PP is low, since the crystals act as light diffusers.
• PP COPO (C-PP): copolymer polypropylene. It is obtained by adding ethylene chains in the polymeric matrix of the PP. It therefore has impact resistance, even at low temperatures, considerably better than the homopolymer PP.
• PP COPO RANDOM (R-PP): random copolymer polypropylene. In this type of PP, the impact resistance better than H-PP is accompanied by good transparency which improves its aesthetic performance (especially at low thicknesses).

It is also possible to compound the PP with the addition of modifiers (glass fibers, glass spheres, mineral fillers) which improve some technical characteristics allowing to obtain products more suited to specific applications.

PP qualitative properties:  it is an economic resin with good impact resistance according to the grades; PP homopolymer can prove fragile at low temperatures, while copolymers are more resistant to impact. PP is wear-resistant, flexible and can withstand very high elongation before breaking. It also shows excellent chemical resistance to acids and alkaline substances.

Applications:

• Automotive;
• Industrial packaging (bottles for detergents, buckets and basins);
• Food packaging (cups, trays, bivalve containers);
• Furniture (such as garden chairs and tables);
• Household goods;
• Caps and closures;
• Coffee capsules;
• Mosquito nets and hail nets.