what is polyethene and what is it used for?

Answer 1

Polyethylene, (IUPAC name polyethene), is a thermoplastic commodity made by the chemical industry and heavily used in consumer products (over 60 million tons are produced worldwide every year).

Polyethylene is classified into several different categories based mostly on its density and branching. The mechanical properties of PE depend significantly on variables such as the extent and type of branching, the crystal structure, and the molecular weight.

UHMWPE (ultra high molecular weight PE)
HMWPE (high molecular weight polyethylene)
HDPE (high density PE)
HDXLPE (high density cross-linked PE)
PEX (cross-linked PE)
MDPE (medium density PE)
LDPE (low density PE)
LLDPE (linear low density PE)
VLDPE (very low density PE)

UHMWPE is polyethylene with a molecular weight numbering in the millions, usually between 3.1 and 5.67 million. The high molecular weight results in less efficient packing of the chains into the crystal structure as evidenced by densities less than high density polyethylene (e.g. 0.935 - 0.930 g/cc). The high molecular weight results in a very tough material. UHMWPE can be made through any catalyst technology, although Ziegler catalysts are most common. Because of its outstanding toughness, cut, wear and excellent chemical resistance, UHWMPE is used in a wide diversity of applications. These include can and bottle handling machine parts, moving parts on weaving machines, bearings, gears, artificial joints, edge protection on ice rinks, butchers' chopping boards. It competes with Aramid in bulletproof vests as Spectra (or Dyneema) fibers.

HDPE is defined by a density of greater or equal to 0.941 g/cc. HDPE has a low degree of branching and thus stronger intermolecular forces and tensile strength. HDPE can be produced by chromium/silica catalysts, Ziegler-Natta catalysts or metallocene catalysts. The lack of branching is ensured by an appropriate choice of catalyst (e.g. Chromium catalysts or Ziegler-Natta catalysts) and reaction conditions. HDPE is used in products and packaging such as milk jugs, detergent bottles, margarine tubs, garbage containers and water pipes.

HDPE is also widely used in the fireworks community. In tubes of varying length (depending on the size of the ordnance), HDPE is used as a replacement for the supplied cardboard mortar tubes for two primary reasons. One, it is much safer than the supplied cardboard tubes because if a shell were to malfunction and explode inside (flower pot) an HDPE tube, the tube will not shatter. The second reason is that they are reusable allowing designers to create multiple shot mortar racks. Pyrotechnicians discourage the use of PVC tubing in mortar tubes because it will shatter, sending shards of plastic at possible spectators, and will not show up in x-rays.

PEX is a medium- to high-density polyethylene containing cross-link bonds introduced into the polymer structure, changing the thermoplast into an elastomer. The high-temperature properties of the polymer are improved, its flow is reduced and its chemical resistance is enhanced. PEX is used in some portable water plumbing systems, as tubes made of the material can be expanded to fit over a metal nipple, and it will slowly return to its original shape, forming a permanent, water-tight connection.

MDPE is defined by a density range of 0.926 - 0.940 g/cc. MDPE can be produced by chromium/silica catalysts, Ziegler-Natta catalysts or metallocene catalysts.MDPE has good shock and drop resistance properties. It also is less notch sensitive than HDPE, stress cracking resistance is better than HDPE. MDPE is typically used in gas pipes and fittings, sacks, shrink film, packaging film, carrier bags, screw closures.

LLDPE is defined by a density range of 0.915 - 0.925 g/cc. is a substantially linear polymer, with significant numbers of short branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins (e.g. 1-butene, 1-hexene, and 1-octene). LLDPE has higher tensile strength than LDPE. Exhibits higher impact and puncture resistance than LDPE. Lower thickness (gauge) films can be blown compared to LDPE, with better environmental stress cracking resistance compared to LDPE but is not as easy to process LLDPE is used in packaging, particularly film for bags and sheets. Lower thickness (gauge) may be used compared to LDPE. Cable covering, toys, lids, buckets and containers, pipe. While other applications are available, LLDPE is used predominantly in film applications due to its toughness, flexibility, and relative transparency.

LDPE is defined by a density range of 0.910 - 0.940 g/cc. LDPE has a high degree of short and long chain branching, which means that the chains do not pack into the crystal structure as well. It has therefore less strong intermolecular forces as the instantaneous-dipole induced-dipole attraction is less. This results in a lower tensile strength and increased ductility. LDPE is created by free radical polymerization. The high degree of branches with long chains gives molten LDPE unique and desirable flow properties. LDPE is used for both rigid containers and plastic film applications such as plastic bags and film wrap.

VLDPE is defined by a density range of 0.880 - 0.915 g/cc. is a substantially linear polymer, with high levels of short chain branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins (e.g. 1-butene, 1-hexene, and 1-octene). VLDPE is most commonly produced using metallocene catalysts due to the greater co-monomer incorporation exhibited by these catalysts. VLDPE’s are used for hose and tubing, ice and frozen food bags, food packaging and stretch wrap, as well as impact modifiers when blended with other polymers.

Answer 2

Polyehethene is a chain polymer formed from the monomer ethene( an unsaturated hydrocarbon).Ethene is C2H4, poly(ethene) is the proper name for polyhtene. It is used for making plastic bags etc.

Answer 3

Polyethene is more commonly known as 'POLYTHENE',, and it is used to make polythene (plastic) sheeting.

Answer 4

Polythene is a type of plastic, you come across it in every day life, usually in the form of transparent plastic sheeting.

Answer 5

CH2=CH-CH=CH-CH= etc........ this is the chain of this polymer.