Informe de polímeros en ingles.

1. Concept of polymer

Are macromolecules (usually organic) formed by the union of smaller molecules called monomers. The starch, cellulose, silk and DNA are examples of natural polymers, among the most common of these and between the synthetic polymers we find nylon, polyethylene and bakelite.

1. Polyolefin

Is called polyolefin to anyone polymer obtained by the polymerisation of olefins. The IUPAC to olefin is "alkene", by which to the polyolefins they can also be called polialquenos.

1. Types of polyolefin Between polyolefins are include, among others, the following products:

• Low-density polyethylene (LDPE or LDPE), formed from ethylene at a very high pressure.
• High-density polyethylene (HDPE or HDPE), which was a product of the polymerisation of ethylene over a catalyst to moderate pressure.
• Linear Low Density Polyethylene (LLDPE or LLDPE), similar to the HDPE but introduced as olefin comonomers longer (especially 1-butene, 1-hexene, 1-octene)
• Polypropylene (PP), which was a product of the catalytic polymerization of propylene.
• Ethylene-propylene rubber (EPR), catalytic copolymer of ethylene and propylene with elastomeric properties.
• Poly-alpha-olefins, obtained from alpha-olefins, linear hydrocarbon with a single double bond in one of its ends, as for example:

• The Hexene.

The polyolefins, as well as the rest of the polymers, are not products defined by a concrete specifications but that each manufacturer offers a wide range of grades with different properties adapted to the specific applications that are to be used. It is important, therefore, does not think in the polyolefins such as chemical substances but as material, as varied in their properties as it may be wood or steel.

1. Polyethylenes

Polyethylene (PE) is chemically the polymer more simple. Is represented by its repetitive unit (CH2-CH2)n. It is one of the most common plastics due to its low price and simplicity in its manufacture, which generates an output of approximately 60 million tonnes per year around the world.2 is chemically inert. It is obtained from the polymerization of ethylene (chemical formula CH2 =CH2 and called ethene by IUPAC), from which it derives its name.

1. Thermoplastic

A thermoplastic is a plastic, to relatively high temperatures, and it becomes flexible or deformable, melts when heated and hardens in a state of vitreous transition when it cools enough. Most of the thermoplastics are polymers of high molecular weight, which possess strings associated by means of Van der Waals forces weak (polyethylene); strong dipole-dipole interactions and hydrogen bonding, or even aromatic rings stacked (polystyrene). The thermoplastic polymers differ from the thermostable polymers or thermos fixed in that after being heated and shaped can overheat and become other objects.

...