Polyethylene bag, Low Density Polyethylene, 360Recup Materials

Polypropylene (PP) is the thermoplastic polymer, partially crystalline, obtained from the polymerization of propylene (or propene). It belongs to the group of polyolefins and is used in a wide variety of applications including packaging for food, fabrics, equipment of laboratory, automotive components and transparent films. It has great resistance against various chemical solvents, as well as against alkalis and acids.

PP homopolymer

The PP obtained from the polymerization of pure propylene is called homopolymer. According to your tacticity, three types are distinguished:

Isotactic PP:

• The regular distribution of the methyl groups gives it a high crystallinity between 70 and 85%, great mechanical resistance and great tenacity. It is the type most used today in injection of parts (screw caps, toys, containers, etc.) and in flat film extrusion to make raffia or as wrapping paper, a substitute for cellophane. Atactic PP. Propylene material that polymerizes leaving the lateral methyls spatially in disorder as shown in the figure. This polymer has such a "stickiness" that allows to adhere to surfaces even in the presence of dust, which is why it is used as a rubber on adhesive papers, or as a base for hot melt adhesives ("hot melt" or "silicone" sticks).

Syndiotactic PP:

• Very little crystalline, having the methyl groups arranged in the form alternating, which makes it more elastic than isotactic PP but also less resistant ..

PP Copolymer

By adding between 5 and 30% of ethylene in the polymerization, a copolymer is obtained that it has higher impact resistance than homopolymer PP. There are, in turn, two types:

Random or random copolymer:

• Ethylene and propylene are introduced at the same time in the same reactor, resulting in polymer chains in which both monomers alternate in a random.

Block copolymer:

• In this case, the polymerization of propylene is first carried out in a reactor and then, in another reactor, ethylene is added which polymerizes on the PP already formed, thus obtaining chains with homogeneous blocks of PP and PE. Impact resistance of These copolymers is very high, which is why they are known as PP impact or PP shock. When the percentage of ethylene exceeds a certain value, the material begins to behave as an elastomer, with very different properties from conventional PP. This product is called Ethylene-Propylene Rubber (EPR).

EPDM Terpolymer

When a third component of the diene type (Butadiene, for example) the result is an Ethylene-Propylene elastomer or rubber, called EPDM.