POLYETHYLENE

Polyethylene is used Chemical drums, jerricans, carboys, toys, picnic ware, household and kitchenware, cable insulation, carrier bags, food wrapping material.
Polyethylene is used to produce various household items such as utensils, eat ware, appliances, electronics, toys and a variety of other individual, everyday items. 
Polyethylene is used in the fabrication of storage containers and tanks of all shapes, sizes and with intended commodities from water, chemicals, food ingredients, syrups, oils, greases, to fuels. 

CAS Number: 9002-88-4
MDL number: MFCD00084423
Molecular Formula: (C2H4)n

SYNONYMS:
PE, Polythene, Polyethene, Ethene Polymer, Ethylene Polymer, High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Linear Low-Density Polyethylene (LLDPE), Ultrahigh Molecular Weight Polyethylene (UHMWPE), Thermoplastic Polyethylene, Polyethene, poly(methylene), Polyethylene, Polythene, LDPE, Etherin, Ethylene Polymers, Polythene, AC 394, Alathon 7140, Alathon 7511, Alcowax 6, Allied PE 617, Alphex FIT 221, Ambythene, Amoco 610A4, BPE-I, Bakelite DHDA 4080, Bakelite DYNH, Bareco polywax 2000, Bicolene C, Bralen KB 2-11, Bulen A, Epolene C, Epolene N, Ethylene polymer, Grex, HI-Fax, Hizex, Hostalen, Poly(ethene), Poly(ethylene), 23F203, 6020P, A 60-20R, A 60-70R, AC 1220, AC 8, AC 8 (Polymer), ACP 6, Acroart, Agilene, Alathon 14, Alathon 15, Alathon 1560, Alathon 5B, Alathon 6600, Alathon 7026, Alathon 7040, Alathon 7050, Alathon 71XHN, Aldyl A, Alithon 7050, Alkathene, Alkathene 17/04/00, Alkathene 200, Alkathene ARN 60, Alkathene WJG 11, Alkathene WNG 14, Alkathene XDG 33, Alkathene XJK 25, Bakelite DFD 330, Bareco wax C 7500, Bralen RB 03-23, Bulen A 30, Carlona 58-030, Carlona 900, Carlona PXB, Chemplex 3006, Coathylene HA 1671, Courlene-X3, Cryopolythene, DFD 0173, DFD 0188, DFD 2005, DFD 6005, DFD 6032, DFD 6040, DFDJ 5505, DGNB 3825, DMDJ 4309, DMDJ 5140, DMDJ 7008, DQDA 1868, DQWA 0355, DXM 100, DYNH, DYNK 2, Diothene, Dixopak, Dylan, Dylan WPD 205, Eltex 6037, Eltex A 1050, Epolene C 10, Epolene C 11, Epolene E, Ethene polymer, Ethylene homopolymer, FB 217, FM 510, Fabritone PE, Fertene, Flamolin MF 15711, Flothene, Fortiflex A 60/500, Grex PP 60-002, Grisolen, HFDB 4201, HI-Fax 1900, HI-Fax 4401, HI-Fax 4601, Hizex 1091J, Hizex 1291J, Hizex 1300J, Hizex 2100J, Hizex 2100LP, Hizex 2200J, Hizex 3000B, Hizex 3000S, Hizex 3300S, Hizex 5000, Hizex 5000S, Hizex 5100, Hizex 5100LP, Hizex 6100P, Hizex 7300F, Hoechst PA 190, Hoechst Wax PA 520, Hostalen GD 620, Hostalen GD 6250, Hostalen GF 4760, Hostalen GF 5750, Hostalen GUR, Hostalen HDPE, Irax, Irrathene R, LD 400, LD 600, Lupolen 1010H, Lupolen 1800H, Lupolen 1800S, Lupolen 1810H, Lupolen 4261A, Lupolen 6011H, Lupolen 6011L, Lupolen 6042D, Lupolen KR 1032, Lupolen KR 1051, Lupolen KR 1257, Lupolen L 6041D, Lupolen N, Manolene 6050, Marlex 50, Marlex 60, Marlex 6003, Marlex 6009, Marlex 6015, Marlex 6050, Marlex 6060, Marlex 9, Marlex 960, Marlex EHM 6001, Marlex M 309, Marlex TR 704, Marlex TR 880, Marlex TR 885, Marlex TR 906, Microthene, Microthene 510, Microthene 704, Microthene 710, Microthene FN 500, Microthene FN 510, Microthene MN 754-18, Mirason 16, Mirason 9, Mirason M 15, Mirason M 50, Mirason M 68, Mirason Neo 23H, Mirathen, Mirathen 1313, Mirathen 1350, Moplen RO-QG 6015, Neopolen, Neopolen 30N, Neozex 4010B, Neozex 45150, Nopol (polymer), Novatec JUO 80, Novatec JVO 80, Okiten G 23, Orizon, Orizon 805, P 2010B, P 2020T, P 2050T, P 2070P, P 4007EU, P 4007T, P 4070L, PA 130, PA 190, PA 520, PA 560, PAD 522, PE 512, PE 617, PEN 100, PEP 211, PES 100, PES 200, PPE 2, PTS 2, PVP 8T, PY 100, Petrothene, Petrothene LB 861, Petrothene LC 731, Petrothene LC 941, Petrothene NA 219, Petrothene NA 227, Petrothene XL 6301, Plaskon PP 60-002, Plastazote X 1016, Plastipore, Plastronga, Plastylene MA 2003, Plastylene MA 7007, Politen, Politen I 020, Poly-Em 12, Poly-Em 40, Poly-Em 41, Polyethylene AS, Polymul CS 81, Polysion N 22, Polywax 1000, Porolen, Profax A 60-008, RCH 1000, Repoc, Rigidex, Rigidex 35, Rigidex 50, Rigidex Type 2, Ropol, SDP 640, SRM 1475, SRM 1476, Sanwax 161P, Sclair 19A, Sclair 19X6, Sclair 2911, Sclair 59, Sclair 59C, Sclair 79D, Sholex 4250HM, Sholex 5003, Sholex 5100, Sholex 6000, Sholex 6002, Sholex F 171, Sholex F 6050C, Sholex F 6080C, Sholex L 131, Sholex S 6008, Sholex super, Socarex, Stamylan 1000, Stamylan 1700, Stamylan 8200, Stamylan 8400, Stamylan 900, Sumikathene, Sumikathene F 101-1, Sumikathene F 210-3, Sumikathene F 702, Sumikathene G 201, Sumikathene G 202, Sumikathene G 801, Sumikathene G 806, Sumikathene hard 2052, Super dylan, Suprathen, Suprathen C 100, Takathene, Takathene P 12, Takathene P 3, Tenaplas, Tenite 1811, Tenite 2910, Tenite 2918, Tenite 3300, Tenite 3340, Tenite 800, Trovidur PE, Tyrin, Tyvek, Unifos DYOB S, Unifos EFD 0118, Valeron, Valspex 155-53, Velustral KPA, Vestolen A 616, WJG 11, WNF 15, WVG 23, Wax LE, XL 1246, XL 335-1, XNM 68, XO 440, Yukalon EH 30, Yukalon HE 60, Yukalon K 3212, Yukalon LK 30, Yukalon MS 30, Yukalon PS 30, Yukalon YK 30, ZF 36, 2100 GP, 2100GP, 5100LP, AC 680, AC GA, AC-GA, ALATHON 4476, ALCOWAX &, ALKATHENE 0764, ALKATHENE HD, ALKATHENE Q 4177, ALKATHENE WNC 71, Alkathene 22 300, BAKELITE DFD 3300, BAYLON V 18, BAYLON VP 105, BRALEN RA 219, BULEN A 15, C 706, CARLONA 18020FA, CELLUSOFT PXB, COURLENE X 3, CPE 16, CPE 25, CPR

Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic.
Polyethylene is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, cups, jars, etc.). 
As of 2017, over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.

Many kinds of polyethylene are known, with most having the chemical formula (C2H4)n. 
Polyethylene is usually a mixture of similar polymers of ethylene, with various values of n. 
Polyethylene can be low-density or high-density and many variations thereof. 

Polyethylene's properties can be modified further by crosslinking or copolymerization. 
All forms are nontoxic as well as chemically resilient, contributing to polyethylene's popularity as a multi-use plastic. 
However, polyethylene's chemical resilience also makes it a long-lived and decomposition-resistant pollutant when disposed of improperly.

Being a hydrocarbon, polyethylene is colorless to opaque (without impurities or colorants) and combustible.
Polyethylene is probably the polymer you see most in daily life. 
Polyethylene is one of the polymers called polyolefins, which is an odd name. 

Many names from the past have nothing to do with the actual chemical compositions of the molecules, but that's a story for another time.
Polyethylene is the most popular plastic in the world. 
This is the polymer that makes grocery bags, shampoo bottles, children's toys, and even bullet proof vests. 

For such a versatile material, Polyethylene has a very simple structure, the simplest of all commercial polymers. 
A molecule of polyethylene is nothing more than a long chain of carbon atoms, with two hydrogen atoms attached to each carbon atom. 
That's what the picture at the top of the page shows, but it might be easier to draw it like the picture below, only with the chain of carbon atoms being many thousands of atoms long.

Sometimes Polyethylene is a little more complicated. 
Sometimes some of the carbons, instead of having hydrogens attached to them, will have long chains or branches of polyethylene attached to them. 
This is called branched, or low-density polyethylene, or LDPE.

When there is no branching, it is called linear polyethylene, or HDPE. 
Linear polyethylene is much stronger than branched polyethylene, but branched polyethylene is cheaper and easier to make. 
It is also more flexible and works great for sandwich wrap.

Linear polyethylene is normally produced with molecular weights in the range of 200,000 to 500,000, but it can be made even higher. 
Polyethylene with molecular weights of three to six million is referred to as ultra-high molecular weight polyethylene, or UHMWPE. 
UHMWPE can be used to make fibers which are so strong they replaced Kevlar for use in bullet proof vests. 

Large sheets of it can be used instead of ice for skating rinks.
Polyethylene is vinyl polymer, made from the monomer ethylene. 
Here's a model of the ethylene monomer. 

Polyethylene  looks like some sort of four-legged headless animal if you ask me.
Branched polyethylene is often made by free radical vinyl polymerization.
Linear polyethylene is made by a more complicated procedure called Ziegler-Natta polymerization. 

UHMWPE is made using metallocene catalysis polymerization.
But Ziegler-Natta polymerization can be used to make LDPE, too. 
By copolymerizing ethylene monomer with a alkyl-branched comonomer one gets a copolymer which has short hydrocarbon branches. 

Copolymers like this are called linear low-density polyethylene, or LLDPE. 
BP produces LLDPE using a comonomer with the catchy name 4-methyl-1-pentene.
LLDPE is often used to make things like plastic films.

Polyethylene is the most common thermoplastic.
Polyethylene can be melted into a liquid and converted back into solid at various times. 
Its durability makes polyethylene attractive for businesses and consumers. 

This plastic, Polyethylene, does not fade or chip. 
Polyethylene is not biodegradable, but it is recyclable. 
Polyethylene is classified into 4 or 5 categories. 

The higher the density the stronger the material:  
*Low-density polyethylene (LDPE)
*Linear low-density polyethylene (LLDPE)
*Medium-density polyethylene (MDPE)
*High-density polyethylene (HDPE)
*Ultra-high molecular weight polyethylene (UWMPE)

Recyclable does not mean sustainable, and Million Marker lists polyethylene as one of the chemicals to avoid. 
Please consider using plastic-free water bottles and eco-friendly food storage containers for your everyday needs. 
Polyethylene (PE) is a thermoplastic polymer of ethylene. 

Polyethylene, the most popular in the world, is a white waxy mass, chemically resistant, cold-resistant, with insulating and shock-absorbing properties, that softens when heated (at 80-120°C), solidifies when cooled and has low adhesion. 
Polyethylene is produced by way of ethylene polymerization. 

There are high-density, low-density and medium-density polyethylenes, depending on the method of production.
Low-density polyethylene (LDPE) has a specific density of 0.91-0.925 g/cm3. 
Low-density polyethylene is characterized by high rigidity, crack-resistance, transparency, flexibility and high elongation, plus low shrinkage during molding.

LDPE has a melting point of 105°C.
It is water-resistant, not reactive in contact with alkali, salt solutions, organic and inorganic acids. 
It is insoluble at room temperature and does not swell in any known solvents. 

Around 80% of LDPE is used for the production of films, mainly packaging films, as well as cable insulation and extrusion when producing cardboard coatings and other materials.
Linear low-density polyethylene (LLDPE) has a melting point of 122°C. 

The primary application of these synthetic polymers is in packaging. Polyethelyne is often used to make plastic bags, bottles, plastic films, containers, and geomembranes. 
Polyethylene is used for frozen food bags, bottles, cereal liners, yogurt containers, etc.

Polyethylene or polythene is a type of polyolefin. 
Polyethylene is often abbreviated as PE. 
The chemical formula of Polyethylene is (C2H4)n. 

Polyethylene is lightweight, durable, and one of the most commonly produced plastic. 
Look around you, all plastics with recycling codes 2 and 4 are made of Polyethylene. 
These plastics come with different crystalline structures.

Polyethylene is made from the polymerization of ethylene (or ethene) monomer. 
The Polyethylene chains are produced by addition or radical polymerization. 
The possible synthesis methods are: Ziegler-Natta Polymerization and Metallocene catalysis

Additionally, other types of PE are also available such as:
*Medium-density polyethylene (MDPE)
*Ultra low-density polyethylene (ULDPE)
*High-molecular-weight polyethylene (HMWPE)
*Metallocene polyethylene (mPE)
*Chlorinated polyethylene (CPE)

Polyethylene, also known as polythene or polyethene, is one of the most commonly used plastics in the world. 
Polyethylenes usually have a linear structure and are known to be addition polymers. 
Polyethylene can be noted that over 100 million tonnes of polyethene is produced on an annual basis for commercial and industrial purposes.

The general formula of polyethylene can be written as (C2H4)n. Most types of polyethylene are thermoplastic (they can be remoulded by heating). 
However, some modified polyethylene plastics exhibit thermosetting properties. 
An example of such a class of polyethylene is cross-linked polyethylene (often abbreviated as PEX).

Polyethylene is a manmade, synthetic material classified as a polyolefin in the collective group known as plastics. 
Polyethylene (abbreviated PE) is sometimes referred to as polyethene, polythene and less commonly as polymethylene. 
Polyethylene is often correlated with its most commonly used product variants: high density (HDPE), low density (LDPE) and cross-linked polyethylene (XLPE; PEX); while other types are also produced. 

The characteristics and classification of the different polyethylene types vary based on the specifics of PE manufacture, its density rating and degree of carbon-to-carbon branching.
At its atomic level, polyethylene is a chain of repeating, single monomer units that are linked together through a synthesis reaction termed polymerization. 

In Polyethylene, the repeating subunit is ethylene, a small carbon compound represented in formula as H2C=CH2 or C2H4. 
When properly reacted, ethylene molecules will form chemical bonds one after the other to produce polyethylene, which is by definition a nonpolar, saturated hydrocarbon polymer chain with high molecular weight. 

The resulting Polyethylene polymer can be further classified as either a thermoplastic or thermoset plastic material. 
Thermoplastics are thermo-softening materials capable of remelting, reuse recycling, and account for most Polyethylene types. 
While thermoset plastics offer certain performance differences, they do not melt on heating but burn, and include the cross linked polyethylene type. 

The resulting polyethylene specs and resin type are fully dependent on how the polymer is manufactured.
Polyethylene (PE) is a thermoplastic polymer composed of ethylene monomers. 
Polyethylene is one of the most commonly used plastics due to its versatility, low cost, and wide range of applications. 

Polyethylene is produced through the polymerization of ethylene gas, resulting in a material with excellent strength, durability, and resistance to chemicals and moisture. 
Polyethylene comes in different forms, such as high-density polyethylene (HDPE) and low-density polyethylene (LDPE), each with its own set of properties and applications.

Polyethylene is one of the world’s most popular plastics. 
Polyethylene is an enormously versatile polymer which is suited to a wide range of applications from heavy-duty damp proof membranes for new buildings to light, flexible bags and films.

Two major types of Polyethylene are in use in the films and flexible packaging sector – LDPE (Low Density) used generally for trays and heavier duty films such as long-life bags and sacks, poly tunnels, protective sheeting, food bags etc and HDPE (High Density) which is used for most thin gauge carrier bags, fresh produce bags and some bottles and caps.

There are other variants on these two main types. 
All offer an good vapour or moisture barrier qualities and are chemically inert.

Polyethylene as is a white powder (microbeads). 
Tough and flexible at room temperatures.
Polyethylene (PE), light, versatile synthetic resin made from the polymerization of ethylene. 

Polyethylene is a member of the important family of polyolefin resins. 
Polyethylene is the most widely used plastic in the world, being made into products ranging from clear food wrap and shopping bags to detergent bottles and automobile fuel tanks.

Polyethylene can also be slit or spun into synthetic fibres or modified to take on the elastic properties of a rubber.
Polyethylene is a type of thermoplastic. 

More specifically, it’s a homopolymer that contains ethene molecular chains. 
This structure is chemically what makes up the plastic we know and use so often, whether it’s for a container that holds your favorite takeout or more serious matters, like part of a knee replacement. 

USES and APPLICATIONS of POLYETHYLENE:
Polyethylene has numerous applications across various industries due to its desirable properties. 
Packaging: Polyethylene is extensively used in packaging materials such as plastic bags, films, and containers due to its excellent moisture barrier properties and flexibility.

Polyethylene is produced in three main forms: low density (LDPE) (< 0.930 g cm-3) and linear low density ( LLDPE) (ca 0.915-0.940 g cm-3) and high density (HDPE) (ca 0.940-0.965 g cm-3).
The LDPE or LLDPE form is preferred for film packaging and for electrical insulation. 

HDPE is blow-moulded to make containers for household chemicals such as washing-up liquids and drums for industrial packaging. 
Polyethylene is also extruded as piping.
The most important application of polyethylene is in packaging products. 

This plastic is often employed for the production of plastic bags, plastic films, bottles, geomembranes, and containers.
Polyethylene is also used in crates, trays, jugs that carry milk or fruit juices, and other food packaging products.
High-density polyethylene is used in toys, garbage containers, ice trays, and other housewares. 

The versatility of this plastic makes Polyethylene ideal for a wide spectrum of applications.
HDPE is also used in ropes, fishing nets, agricultural nets, and industrial fabrics. 
It is not uncommon for this plastic to be used in wirings and cables as well.

Low-density polyethylene (LDPE) is widely used in the production of squeeze bottles, garbage bags, laminations, and food packaging due to its high flexibility and low cost.
LDPE is also used in pipes and fittings. 

It is ideal for such applications due to its low water absorption and also due to its plasticity.
Polyethylene is also used for cable jacketing since it is a good insulator of electric current.
By altering the formulation and gauge of polyethylene, the producer/converter can adjust impact and tear resistance; transparency and tactility; flexibility, formability and coating/laminating/printing capability. 

Polyethylene can be recycled and many bin bags, agricultural films and long-life products such as park benches, bollards and waste bins use recycled polyethylene. 
Due to its high calorific value, Polyethylene offers excellent energy recovery through clean incineration.

Polyethylene is used Chemical drums, jerricans, carboys, toys, picnic ware, household and kitchenware, cable insulation, carrier bags, food wrapping material.
Polyethylene is used to produce various household items such as utensils, eat ware, appliances, electronics, toys and a variety of other individual, everyday items. 

Polyethylene is used in the fabrication of storage containers and tanks of all shapes, sizes and with intended commodities from water, chemicals, food ingredients, syrups, oils, greases, to fuels. 
Frequent chemical types used with Polyethylene include strong acids such as hydrochloric acid, strong caustics such as sodium hydroxide, and potential oxidizers such as sodium hypochlorite (bleach). 

Polyethylene is often used to manufacture pipes and tubing that are widely used for fluid transfer, pumps and delivery systems. 
Other common examples of Polyethylene use include healthcare equipment, electrical components and wiring sheaths, as well as structural materials used in construction. 

The wide use and extensive versatility of polyethylene can be contributed to its unique physical and chemical properties as well as its capability to be modified and/or developed into its different characteristic strains.
Polyethylene is a fairly recent implementation in the field of material science and polymer engineering, as are all plastics. 

Polyethylene further categorizes into thermoplastics such as HDPE, LDPE and thermosets such as XLPE/PEX. 
Polyethylene is a long carbon chain polymer made of ethylene refined from natural oils and gas resources. 

Among the different plastic types, polyethylene is one of the world’s most manufactured, fabricated and engineered plastics next to polypropylene. 
Polyethylene is commonly used in the production of many modern-day items as well as applications that range from manufacturing to commodity handling. 

As a product material option, polyethylene is a durable, comparatively low cost and corrosion resistant synthetic material that offers significant compatibility within chemical scenarios to water use to food grade operations. 
Polyethylene is used in various industries, including packaging, agriculture, construction, automotive, and healthcare. 

-Construction uses of Polyethylene:
Polyethylene is widely used in the construction industry for pipes, fittings, geomembranes, and insulation materials. 
Polyethylene pipes are durable, lightweight, and resistant to corrosion, making them ideal for water and gas distribution systems.

-Automotive uses of Polyethylene: 
Polyethylene is used in automotive applications for manufacturing fuel tanks, bumpers, cable insulation, and interior components. 
Its impact resistance, low weight, and chemical resistance make Polyethylene suitable for these applications.

-Agriculture uses of Polyethylene: 
Polyethylene is used in agricultural applications such as greenhouse films, mulching films, and irrigation systems. 
These films provide protection against pests, control moisture levels, and enhance crop growth.

-Electrical insulation uses of Polyethylene: 
Polyethylene is used as an insulating material in electrical wires and cables. 
Its excellent electrical properties, including high dielectric strength and low dielectric loss, make Polyethylene an ideal choice for insulation.

-Consumer goods uses of Polyethylene: 
Polyethylene is found in a wide range of consumer products, including toys, household containers, bottles, and packaging for food and beverages. 
Its safety, durability, and ease of molding make Polyethylene popular in these applications.

-Medical uses of Polyethylene: 
In the medical field, polyethylene is used for manufacturing medical devices and packaging materials. 
Polyethylene is commonly used for items such as syringes, catheters, surgical implants, and flexible packaging for pharmaceuticals.

-Sports and recreation uses of Polyethylene: 
Polyethylene is used in the production of sports equipment, such as kayaks, canoes, playground equipment, and artificial turf. 
Polyethylene's lightweight nature, durability, and impact resistance contribute to its suitability for these applications.

-Industrial applications of Polyethylene: 
Polyethylene is employed in various industrial applications, including chemical storage tanks, liners for ponds and reservoirs, conveyor belts, and industrial coatings. 
Its chemical resistance and low friction properties make Polyethylene useful in these environments.

-Applications of Polyethylene
There are many different ways that we use polyethylene, from day-to-day products to more niche items. 
Some of the most common products include:
*Fishing nets
*Bottles
*Water tanks
*Bags and food containers
*Pipes and pipe fittings
*Flexible films
*Medical implants
*Ropes
*Wear-resistant liners for objects like chutes

WHAT IS POLYETHYLENE USED FOR?
Polyethylene is one of the world’s most used plastic material types in terms of market abundance, production weight, and diversity among resulting products. 
Polyethylene resins are used in blow molding, rotational molding or push method extrusion processes to produce the wide variety of PE products across industries and applications. 
Agriculture, chemical processing, consumer products, healthcare and pharmaceutics, plumbing, commodity handling, logistics and storage are a few example industries that make use of polyethylene. 

TYPES OF POLYETHYLENE:
Polyethylene can be classified into several different types based on the density of the plastic and the degree of branching in its structure. 
The type of branching and the extent of branching have a direct impact on the mechanical properties of the plastic. 

Therefore, different types of polyethylene exhibit different mechanical properties. 
Some important types of polyethylene are listed below.

*High modulus polyethylene, also known as ultra-high molecular weight polyethylene (UHMWPE)
*Ultra-low-molecular-weight polyethylene (or ULMWPE)
*High-density cross-linked polyethylene (HDXLPE)
*High-density polyethylene (HDPE)
*High-molecular-weight polyethylene (HMWPE)
*Cross-linked polyethylene (XLPE)
*Medium-density polyethylene (MDPE)
*Low-density polyethylene (LDPE)
*Linear low-density polyethylene (LLDPE)
*Chlorinated polyethylene (CPE)

It can also be noted that low-density polyethylene exhibits lower crystallinity than high-density polyethylene. 
The crystallinity of polythene is known to range from 35% for low-density polyethylene to 80% for high-density polyethylene.

WHAT ARE THE PHYSICAL AND CHEMICAL PROPERTIES OF POLYETHYLENE?
Physical Properties
The mechanical strength of polyethylene is relatively lower than other plastics. 
The rigidity and the hardness of these polymers are also relatively low.

Polyethylene is known to be highly ductile. 
Furthermore, this plastic is known to possess very high impact strength.
This synthetic polymer, Polyethylene, exhibits strong creep when placed under a persistent force.

Polyethylenes usually have a waxy texture.
The melting points of commercial grades of high-density polyethylene (HDPE) and medium-density polyethylene (MDPE) lie in the range of 120 – 180 degrees Celsius.

The melting point of the commercially available low-density polyethylene (LDPE) usually lies in the range of 105 – 115 degrees Celsius.
Polyethylene is known to be a very good insulator of electric current since it offers high electrical treeing resistance.

Chemical Properties
Polyethylene is made up of nonpolar saturated hydrocarbons with very high molecular weights. 
This is believed to be the reason why the chemical properties exhibited by polyethylene are quite similar to those of paraffin. 

It can be noted that the individual polyethylene macromolecules are not linked via covalent bonds. 
However, these molecules crystallize due to their rather symmetric molecular structures. 

Therefore, polythene can be considered as partially crystalline plastic. 
The greater the crystallinity of the polymer, the greater Polyethylene's density and chemical stability.

It is important to note that most types of polyethylene have very high chemical resistance towards acids and alkalis (including LDPE, MDPE, and HDPE). 
These plastics are also resistant to weak oxidizing agents and weak reducing agents. 
Most polyethylenes are known to be soluble in aromatic hydrocarbons like xylene or toluene under elevated temperatures.

POLYETHYLENE FEATURES:
Polyethylene is a versatile synthetic polymer that has numerous features and applications. 
Here are some key features of polyethylene:

Lightweight: 
Polyethylene is a lightweight material, making it easy to handle and transport.

Chemical resistance: 
Polyethylene has excellent resistance to many chemicals, including acids, alkalis, and solvents, which makes it suitable for various industrial applications.

Water resistance: 
Polyethylene is highly resistant to water, making it useful for products that need to be water-resistant or waterproof.

Electrical insulation: 
Polyethylene has good electrical insulation properties, making it suitable for applications in the electrical and electronics industries.

Flexibility: 
Polyethylene is a flexible material, allowing it to be easily molded into different shapes and sizes. 
Polyethylene can also withstand repeated bending and flexing without breaking.

Low friction: 
Polyethylene has a low coefficient of friction, which means that objects can slide easily over its surface. 
This property makes Polyethylene suitable for applications where reduced friction is desired, such as in packaging and conveyor systems.

Thermal insulation: 
Polyethylene has low thermal conductivity, providing insulation against heat transfer. 
Polyethylene is commonly used in insulation materials for pipes, cables, and construction applications.

Impact resistance: 
Polyethylene exhibits high impact strength, making it resistant to breaking or shattering under impact loads. 
This property is particularly useful in applications where durability is required, such as in packaging, automotive parts, and toys.

Food-safe: 
Polyethylene is non-toxic and approved for use in food packaging and containers, as it does not leach harmful substances into food.

UV resistance: 
Some forms of polyethylene are resistant to ultraviolet (UV) radiation, making them suitable for outdoor applications where prolonged exposure to sunlight is expected, such as in agricultural films and outdoor furniture.

These features contribute to the widespread use of polyethylene in various industries, including packaging, construction, automotive, electrical, agriculture, and healthcare.

PREPARATION OF POLYETHYLENE:
The primary constituent of polyethylene is ethylene (an organic hydrocarbon with the chemical formula C2H4; IUPAC name: ethene). 
For the production of polyethylene, the typical specifications involve less than 5 parts per million of oxygen, water, and other alkenes. 

However, other compounds can be present during the polymerization reaction as contaminants. 
Some commonly accepted contaminants during the production of polythene include nitrogen, methane, and ethane.

Since ethene is a relatively stable molecule, its polymerization requires suitable catalysts. 
It is important to note that the conversion of ethylene into polyethylene is highly exothermic in nature. 
One of the most commonly used catalysts for the polymerization of ethylene is titanium(III) chloride (which is sometimes referred to as a Ziegler-Natta catalyst).

PROPERTIES OF POLYETHYLENE:
Flexible, translucent/waxy, weatherproof, good low temperature toughness (to -60'C), easy to process by most methods, low cost, good chemical resistance.

STRENGHTS OF POLYETHYLENE:
*Worldwide presence
*Multiple technology platforms (e.g., autoclave, gas phase, loop slurry)

BENEFITS OF POLYETHYLENE:
*World-class research and development
*Commitment to customer service and support
*Global production and distribution

WHAT TYPE OF MATERIAL IS POLYETHYLENE?
Polyethylene is a thermoplastic polyolefin. 
Polyethylene is a poleolefin is a hydrocarbon polymer made from a monomer that has a double bond, in this case, ethylene. 
A thermoplastic can be shaped by heating into a mold, rolled into a film, or extended into a thread, and can be reshaped the same way at a later time. 
Polyethylene forms a durable, lightweight, waterproof solid that is inexpensive and used for packaging and containers.

IS POLYETHYLENE TOXIC TO HUMANS?
Pure polyethylene is biocompatible, chemically stable, and non-toxic to humans. 
However, over time, polyethylene can absorb toxic materials such as heavy metals and pesticides that may pose a health risk or irritant to humans. 
This degraded form may enter the food chain or affect the human water supply, and is particularly important in the case of oceanic microplastics.

IS POLYETHYLENE A COMPOUND OR AN ELEMENT?
Polyethylene is a compound is any molecule made of two or more elements. 
Polyethylene is a covalently bonded compound made from two elements in the form of a polymer. 
A polymer is a chain of connected small molecules, or monomers. 

In this case the polymer contains only carbon and hydrogen elements. 
The carbon atoms form a carbon-carbon chain, and the hydrogen atoms are attached to each carbon in the very stable structure of polyethylene.

WHAT IS THE DIFFERENCE BETWEEN PLASTIC AND POLYETHYLENE?
A plastic is an organic (carbon-based), man-made polymer that can be molded. 
Polyethylene is the largest sub-set of plastics. 
Other common plastics include styrofoam, cellophane, and polypropylene. 
Polypropyelene is often used for plastic drinking straws and HEPA filters.

IMPORTANT POLYETHYLENE CHARACTERISTICS AND PROPERTIES:
The specifications and properties of polyethylene depend entirely on how the resin is processed and what additives if any have been included. 
Details such as density, specific gravity, molecular weight, temperature maximums and minimums, chemical sensitivity, physical durability and its total amorphous state versus crystalline state all vary on the degree of polyethylene branching and its specific processing. 

When polyethylene is compared among plastics and other material types in general, PE is reported as durable, resilient against impacts, tears and drops, and resistant to chemical corrosion, rust and weathering. 

When fabricated with the additive carbon black or titanium dioxide, Polyethylene also becomes resistant to sunlight UV degradation and long term suitable for outdoor use. 

In terms of chemical strength, polyethylene has marked chemical compatibility and can be significantly more resistant than other materials, even metals, depending on the chemical to be handled. 

The maximum service temperature is dependent on the specific Polyethylene strain as well as additives and design specifications. 
HDPE is commonly rated to a sustained service temp of 100°F, with maximum spikes to 120°F – 130°F. 

XLPE is rated to a sustained service temp of 100°F, with maximum spikes to 130°F – 140°F. 
LDPE max temperature ratings are around 110°F. 
Note these values are for continuous storage and operation temperatures, not the materials’ melting temperatures. 

Additional characteristics of Polyethylene include it is lightweight, maneuverable, moldable, and with a fairly low production cost that provides cost-effectiveness in terms of purchase price, installation and service life.

FORMULATION OF POLYETHYLENE:
There are different types of polyethylene formulations available, each with specific characteristics suited for particular uses. 
Here are a few commonly used polyethylene formulations:

Low-density polyethylene (LDPE): 
LDPE has a high degree of branching in its molecular structure, resulting in a low-density and flexible material. 
It is used in packaging films, plastic bags, and squeeze bottles.

High-density polyethylene (HDPE): 
HDPE has a more linear molecular structure, leading to higher density and greater strength. 
It is used in applications requiring rigidity, such as pipes, containers, and geomembranes.

Linear low-density polyethylene (LLDPE): 
LLDPE is a blend of LDPE and linear polyethylene. 
It combines the flexibility of LDPE with the strength of HDPE. 
LLDPE is commonly used in film applications, such as stretch wrap, agricultural films, and liners.

Medium-density polyethylene (MDPE): 
MDPE is a material with properties falling between LDPE and HDPE. 
It is used in applications that require a balance of strength and flexibility, such as gas pipes and cable insulation.

Ultra-high-molecular-weight polyethylene (UHMWPE): 
UHMWPE has an extremely high molecular weight, resulting in exceptional wear resistance and impact strength. 
It is used in applications like bearings, gears, and medical implants.

These are just a few examples of Polyethylene formulations, and there are many other variations and blends available to cater to specific requirements in industries such as packaging, construction, automotive, and more.

RESISTANCE TO CHEMICALS:
Dilute Acid ****
Dilute Alkalis ****
Oils and Greases ** variable
Aliphatic Hydrocarbons *
Aromatic Hydrocarbons *
Halogenated Hydrocarbons *
Alcohols ****

RECYCLING OF POLYETHYLENE:
Polyethylene can be recycled into new products, including plastic lumber, plastic bags, and composite materials. 
Recycling helps reduce waste and conserves resources.
These are just a few examples of the many applications of polyethylene, highlighting its versatility and widespread use across different industries.

HOW IS POLYETHYLENE MADE?
Polyethylene belongs to a class of polymer materials that are made from petroleum hydrocarbon refinery by-products. 
Ethylene gas in particular is used to make polyethylene and belongs to the naptha group of natural oil derived substances along with propene (propylene; C3H6), butene (C4H8), benzene and xylene, amongst others. 

Ethylene is a secondary product generated from the natural oil or gas cracking process that is used to produce modern combustion fuels. 
Polypropylene, Polystyrene, Polyvinyl Chloride (PVC) and Nylon also belong to this category. 

For polyethylene production, the ethylene gas starting material is reacted under particular temperatures, pressures and available catalysts that together induce polymerization of the ethylene compound. 

Polyethylene synthesis temperatures range from 158°F (70°C) to 572°F (300°C); common pressures range from 9.8 atm (144 psi) to 296 atm (4350 psi); and the Ziegler-Natta catalyst, so named after initial PE researchers, is the most frequently used catalyst. 

Depending on the details of the polymerization reaction, the result will be polyethylene with a specific degree of molecular branching, density, and linking that will place the resulting product in one of PE’s various classifications. 

The standard, most used polyethylene resin classifications are:
*Low density (LDPE)
*Linear low density (LLDPE)
*Medium density (MDPE)
*High density (HDPE)
*Ultra high molecular weight (UHMWPE)
*Ultra low molecular weight (ULMWPE)
*Cross-linked polyethylene (XLPE; PEX)
*Chlorinated polyethylene (CPE)

The different types of Polyethylene will vary in their chemical and physical properties as well as any potential additives included during manufacture. 
Polyethylene additives can modify PE appearance by adding colorants, enhance its malleability through plasticizers, provide UV and weather protection with antioxidants, and increase its resistance to fire and microbial growth, to name a few examples. 

Additives are frequently included during manufacture to further modify Polyethylene’s characteristics and often to match the specific needs of an individual application. 

WHAT PRODUCTS HAVE POLYETHYLENE IN THEM?
Polyethylene can be found in:
*Food packaging 
*Medical tubing 
*Bottles and bins 
*Bulletproof vests 
*High-tensile cables 
Its durable nature also makes polyethylene an electrical insulator. 

HISTORY OF POLYETHYLENE:
Polyethylene was first synthesized by the German chemist Hans von Pechmann, who prepared it by accident in 1898 while investigating diazomethane.
When his colleagues Eugen Bamberger and Friedrich Tschirner characterized the white, waxy substance that he had created, they recognized that Polyethylene contained long −CH2− chains and termed it polymethylene.

The first industrially practical polyethylene synthesis (diazomethane is a notoriously unstable substance that is generally avoided in industrial syntheses) was again accidentally discovered in 1933 by Eric Fawcett and Reginald Gibson at the Imperial Chemical Industries (ICI) works in Northwich, England.
Upon applying extremely high pressure (several hundred atmospheres) to a mixture of ethylene and benzaldehyde they again produced a white, waxy material. 

Because the reaction had been initiated by trace oxygen contamination in their apparatus, the experiment was difficult to reproduce at first. 
It was not until 1935 that another ICI chemist, Michael Perrin, developed this accident into a reproducible high-pressure synthesis for polyethylene that became the basis for industrial low-density polyethylene (LDPE) production beginning in 1939. 

Because polyethylene was found to have very low-loss properties at very high frequency radio waves, commercial distribution in Britain was suspended on the outbreak of World War II, secrecy imposed, and the new process was used to produce insulation for UHF and SHF coaxial cables of radar sets. 

During World War II, further research was done on the ICI process and in 1944, DuPont at Sabine River, Texas, and Union Carbide Corporation at South Charleston, West Virginia, began large-scale commercial production under license from ICI.

The landmark breakthrough in the commercial production of polyethylene began with the development of catalysts that promoted the polymerization at mild temperatures and pressures. 

The first of these was a catalyst based on chromium trioxide discovered in 1951 by Robert Banks and J. Paul Hogan at Phillips Petroleum.
In 1953 the German chemist Karl Ziegler developed a catalytic system based on titanium halides and organoaluminium compounds that worked at even milder conditions than the Phillips catalyst. 

The Phillips catalyst is less expensive and easier to work with, however, and both methods are heavily used industrially. 
By the end of the 1950s both the Phillips- and Ziegler-type catalysts were being used for high-density polyethylene (HDPE) production. 

In the 1970s, the Ziegler system was improved by the incorporation of magnesium chloride. 
Catalytic systems based on soluble catalysts, the metallocenes, were reported in 1976 by Walter Kaminsky and Hansjörg Sinn. 

The Ziegler- and metallocene-based catalysts families have proven to be very flexible at copolymerizing ethylene with other olefins and have become the basis for the wide range of polyethylene resins available today, including very-low-density polyethylene and linear low-density polyethylene. Such resins, in the form of UHMWPE fibers, have (as of 2005) begun to replace aramids in many high-strength applications.

Polyethylene is the largest volume polymer produced globally, with a total over 90 million metric tons per annum. 
Since Polyethylene's accidental discovery in 1933 it has evolved into a material critical to modern life. 

The first product commercialized was low density polyethylene (LDPE) based on free radical polymerization. 
Shortly thereafter new polymerization chemistries based on chromium catalysis and Ziegler Natta catalysis expanded the product space. 
Improved polymer performance based on new catalyst and application technologies have made Polyethylene possible to have the diversity of use we see today. 

Polyethylene is an essential material to power transmission, food packaging, consumer goods, electronics, household goods, industrial storage, transportation industries. 
Developments in technology continues to improve its functionality making polyethylene the most efficient use of natural resources petroleum and natural gas.

PROPERTIES OF POLYETHYLENE:
The properties of polyethylene depend strongly on type. 
The molecular weight, crosslinking, and presence of comonomers all strongly affect Polyethylene's properties. 

Polyethylene is for this structure-property relation that intense effort has been invested into diverse kinds of PE.
LDPE is softer and more transparent than HDPE. 

For medium- and high-density polyethylene the melting point is typically in the range 120 to 130 °C (248 to 266 °F). 
The melting point for average commercial low-density polyethylene is typically 105 to 115 °C (221 to 239 °F). 

These temperatures vary strongly with the type of polyethylene, but the theoretical upper limit of melting of polyethylene is reported to be 144 to 146 °C (291 to 295 °F). 
Combustion typically occurs above 349 °C (660 °F).

Most LDPE, MDPE, and HDPE grades have excellent chemical resistance, meaning that they are not attacked by strong acids or strong bases and are resistant to gentle oxidants and reducing agents. 

Crystalline samples do not dissolve at room temperature. Polyethylene (other than cross-linked polyethylene) usually can be dissolved at elevated temperatures in aromatic hydrocarbons such as toluene or xylene, or in chlorinated solvents such as trichloroethane or trichlorobenzene.

Polyethylene absorbs almost no water; the gas and water vapour permeability (only polar gases) is lower than for most plastics. 
Oxygen, carbon dioxide and flavorings, on the other hand, can pass Polyethylene easily.

Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odour of paraffin (similar to candle flame). 
Polyethylene continues burning on removal of the flame source and produces a drip.

Polyethylene cannot be imprinted or bonded with adhesives without pretreatment. 
High-strength joints are readily achieved with plastic welding.

*Electrical
Polyethylene is a good electrical insulator. 
Polyethylene offers good electrical treeing resistance; however, it becomes easily electrostatically charged (which can be reduced by additions of graphite, carbon black or antistatic agents). 

When pure, the dielectric constant is in the range 2.2 to 2.4 depending on the density and the loss tangent is very low, making Polyethylene a good dielectric for building capacitors. 
For the same reason Polyethylene is commonly used as the insulation material for high-frequency coaxial and twisted pair cables.

*Optical
Depending on thermal history and film thickness, Polyethylene can vary between almost clear (transparent), milky-opaque (translucent) and opaque. 
LDPE has the greatest, LLDPE slightly less, and HDPE the least transparency. 
Transparency is reduced by crystallites if they are larger than the wavelength of visible light

ADVANTAGES OF POLYETHYLENE:
high softening temperature (which allows to use it for hot products packaging), excellent performance characteristics at low and high temperatures, surface gloss and crack-resistance. 
It is used for the production of stretch films, shrink films and bags for heavy-weight goods and waste. 

LLDPE is used for the production of frozen food packaging due to its performance characteristics at low temperatures. 
The use of this polymer in the production of stretch films is rapidly growing.

Medium-density polyethylene (MDPE) has a specific density of around 940 kg/m3. 
It is highly shock- and fracture-resistant. 

Medium-density polyethylene has better scratch- and crack-resistance compared to HDPE (high-density polyethylene). 
MDPE is used for the production of conventional and shrink films, bags, shopping bags and screw caps.

High-density Polyethylene (HDPE) has a specific density of 0.941-0.959 g/cm3. 
HDPE is characterized by excellent rigidity, wear-resistance, chemical resistance and surface gloss. 
Since HDPE is more rigid than other polyethylenes, it is used for blow molding of bottles, barrels and cans and the extrusion of gas and water pipes. 

When mixed with LDPE, it is well suited for the production of films since LDPE and HDPE are fully compatible. 
This polyethylene is highly suitable for the production of foam materials for thermal insulation and for protection from mechanical damages (PPE).

In addition to main polyethylene types (LDPE, HDPE), medium-density polyethylene (MDPE), cross-linked polyethylene (PE-X) and ultra-high-molecular-weight polyethylene (UHMWPE) are also used for industrial purposes. 
Polyethylene is processed using all known plastics processing methods - extrusion, extrusion blowing, injection molding, pneumatic molding and rotational molding.

MANUFACTURING PROCESS OF POLYETHYLENE:
*Monomer
The ingredient or monomer is ethylene (IUPAC name ethene), a gaseous hydrocarbon with the formula C2H4, which can be viewed as a pair of methylene groups (−CH2−) connected to each other. 
Typical specifications for PE purity are <5 ppm for water, oxygen, and other alkenes contents. 

Acceptable contaminants include N2, ethane (common precursor to ethylene), and methane. 
Ethylene is usually produced from petrochemical sources, but is also generated by dehydration of ethanol.

*Polymerization
Polymerization of ethylene to polyethylene is described by the following chemical equation:
n CH2=CH2 (gas) → [−CH2−CH2−]n (solid) ΔH/n = −25.71 ± 0.59 kcal/mol (−107.6 ± 2.5 kJ/mol)

Ethylene is a stable molecule that polymerizes only upon contact with catalysts. 
The conversion is highly exothermic. 
Coordination polymerization is the most pervasive technology, which means that metal chlorides or metal oxides are used. 

The most common catalysts consist of titanium(III) chloride, the so-called Ziegler–Natta catalysts. 
Another common catalyst is the Phillips catalyst, prepared by depositing chromium(VI) oxide on silica.
Polyethylene can be produced through radical polymerization, but this route has only limited utility and typically requires high-pressure apparatus.

*Joining
Commonly used methods for joining polyethylene parts together include:
*Welding
*Hot gas welding
*Infrared welding
*Laser welding
*Ultrasonic welding
*Heat sealing
*Heat fusion
*Fastening
*Adhesives
*Pressure-sensitive adhesive (PSAs)
*Dispersion of solvent-type PSAs
*Polyurethane contact adhesives
*Two-part polyurethane
*Epoxy adhesives
*Hot-melt adhesives
*Solvent bonding – Adhesives and solvents are rarely used as solvent bonding because polyethylene is nonpolar and has a high resistance to solvents.
Pressure-sensitive adhesives (PSA) are feasible if the surface chemistry or charge is modified with plasma activation, flame treatment, or corona treatment.

CLASSIFICATION OF POLYETHYLENE:
Polyethylene is classified by its density and branching. 
Its mechanical properties depend significantly on variables such as the extent and type of branching, the crystal structure, and the molecular weight. 

There are several types of polyethylene:
*Ultra-high-molecular-weight polyethylene (UHMWPE)
*Ultra-low-molecular-weight polyethylene (ULMWPE or PE-WAX)
*High-molecular-weight polyethylene (HMWPE)
*High-density polyethylene (HDPE)
*High-density cross-linked polyethylene (HDXLPE)
*Cross-linked polyethylene (PEX or XLPE)
*Medium-density polyethylene (MDPE)
*Linear low-density polyethylene (LLDPE)
*Low-density polyethylene (LDPE)
*Very-low-density polyethylene (VLDPE)
*Chlorinated polyethylene (CPE)
With regard to sold volumes, the most important polyethylene grades are HDPE, LLDPE, and LDPE.

*Ultra-high-molecular-weight (UHMWPE)
UHMWPE is polyethylene with a molecular weight numbering in the millions, usually between 3.5 and 7.5 million amu.

The high molecular weight makes it a very tough material, but results in less efficient packing of the chains into the crystal structure as evidenced by densities of less than high-density polyethylene (for example, 0.930–0.935 g/cm3). 

UHMWPE can be made through any catalyst technology, although Ziegler catalysts are most common. 
Because of its outstanding toughness and its cut, wear, and excellent chemical resistance, UHMWPE is used in a diverse range of applications. 

These include can- and bottle-handling machine parts, moving parts on weaving machines, bearings, gears, artificial joints, edge protection on ice rinks, steel cable replacements on ships, and butchers' chopping boards. 

It is commonly used for the construction of articular portions of implants used for hip and knee replacements. 
As fiber, it competes with aramid in bulletproof vests.

*High-density polyethylene (HDPE)
HDPE is defined by a density of greater or equal to 0.941 g/cm3. HDPE has a low degree of branching. 
The mostly linear molecules pack together well, so intermolecular forces are stronger than in highly branched polymers. 

HDPE can be produced by chromium/silica catalysts, Ziegler–Natta catalysts or metallocene catalysts; by choosing catalysts and reaction conditions, the small amount of branching that does occur can be controlled. 

These catalysts prefer the formation of free radicals at the ends of the growing polyethylene molecules. 
They cause new ethylene monomers to add to the ends of the molecules, rather than along the middle, causing the growth of a linear chain.

HDPE has high tensile strength. 
It is used in products and packaging such as milk jugs, detergent bottles, butter tubs, garbage containers, and water pipes.

*Cross-linked polyethylene (PEX or XLPE)
PEX is a medium- to high-density polyethylene containing cross-link bonds introduced into the polymer structure, changing the thermoplastic into a thermoset. 

The high-temperature properties of the polymer are improved, its flow is reduced, and its chemical resistance is enhanced. 
PEX is used in some potable-water plumbing systems because 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.

*Medium-density polyethylene (MDPE)
MDPE is defined by a density range of 0.926–0.940 g/cm3. 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, and screw closures.

*Linear low-density polyethylene (LLDPE)
LLDPE is defined by a density range of 0.915–0.925 g/cm3. 
LLDPE is a substantially linear polymer with significant numbers of short branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins (for example, 1-butene, 1-hexene, and 1-octene). 

LLDPE has higher tensile strength than LDPE, and it exhibits higher impact and puncture resistance than LDPE. 
Lower-thickness (gauge) films can be blown, compared with LDPE, with better environmental stress cracking resistance, but they are not as easy to process. 
LLDPE is used in packaging, particularly film for bags and sheets. Lower thickness may be used compared to LDPE. 

It is used for cable coverings, toys, lids, buckets, containers, and pipe. 
While other applications are available, LLDPE is used predominantly in film applications due to its toughness, flexibility, and relative transparency. 
Product examples range from agricultural films, Saran wrap, and bubble wrap to multilayer and composite films.

*Low-density polyethylene (LDPE)
LDPE is defined by a density range of 0.910–0.940 g/cm3. 
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 branching 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.

The radical polymerization process used to make LDPE does not include a catalyst that "supervises" the radical sites on the growing PE chains. 
(In HDPE synthesis, the radical sites are at the ends of the PE chains, because the catalyst stabilizes their formation at the ends.) 

Secondary radicals (in the middle of a chain) are more stable than primary radicals (at the end of the chain), and tertiary radicals (at a branch point) are more stable yet. 

Each time an ethylene monomer is added, it creates a primary radical, but often these will rearrange to form more stable secondary or tertiary radicals. 
Addition of ethylene monomers to the secondary or tertiary sites creates branching.

*Very-low-density Polyethylene (VLDPE)
VLDPE is defined by a density range of 0.880–0.915 g/cm3. 
VLDPE is a substantially linear polymer with high levels of short-chain branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins (for example, 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. 
VLDPEs 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.

Much research activity has focused on the nature and distribution of long chain branches in polyethylene. 
In HDPE, a relatively small number of these branches, perhaps one in 100 or 1,000 branches per backbone carbon, can significantly affect the rheological properties of the polymer.

COPOLYMERS OF POLYETHYLENE:
In addition to copolymerization with alpha-olefins, ethylene can be copolymerized with a wide range of other monomers and ionic composition that creates ionized free radicals. 

Common examples include vinyl acetate (the resulting product is ethylene-vinyl acetate copolymer, or EVA, widely used in athletic-shoe sole foams) and a variety of acrylates.
Applications of acrylic copolymer include packaging and sporting goods, and superplasticizer, used in cement production.

TYPES OF POLYETHYLENES:
The particular material properties of "polyethylene" depend on its molecular structure. 
Molecular weight and crystallinity are the most significant factors; crystallinity in turn depends on molecular weight and degree of branching. 
The less the polymer chains are branched, and the lower the molecular weight, the higher the crystallinity of polyethylene. 

Crystallinity ranges from 35% (PE-LD/PE-LLD) to 80% (PE-HD). 
Polyethylene has a density of 1.0 g/cm3 in crystalline regions and 0.86 g/cm3 in amorphous regions. 
An almost linear relationship exists between density and crystallinity.

CHAIN BRANCHES OF POLYETHYLENE:
The properties of polyethylene are highly dependent on type and number of chain branches. 
The chain branches in turn depend on the process used: either the high-pressure process (only PE-LD) or the low-pressure process (all other PE grades). 

Low-density polyethylene is produced by the high-pressure process by radical polymerization, thereby numerous short chain branches as well as long chain branches are formed. 

Short chain branches are formed by intramolecular chain transfer reactions, they are always butyl or ethyl chain branches because the reaction proceeds after the following mechanism.

CHEMICALLY MODIFIED POLYETHYLENE:
Chemically modified polyethylene
Polyethylene may either be modified in the polymerization by polar or non-polar comonomers or after polymerization through polymer-analogous reactions. 
Common polymer-analogous reactions are in case of polyethylene crosslinking, chlorination and sulfochlorination.

*Non-polar ethylene copolymers
α-olefins

In the low pressure process α-olefins (e.g. 1-butene or 1-hexene) may be added, which are incorporated in the polymer chain during polymerization. 
These copolymers introduce short side chains, thus crystallinity and density are reduced. 

As explained above, mechanical and thermal properties are changed thereby. 
In particular, PE-LLD is produced this way.

*Metallocene polyethylene (PE-MC)
Metallocene polyethylene (PE-M) is prepared by means of metallocene catalysts, usually including copolymers (z. B. ethene / hexene). 

Metallocene polyethylene has a relatively narrow molecular weight distribution, exceptionally high toughness, excellent optical properties and a uniform comonomer content. 
Because of the narrow molecular weight distribution it behaves less pseudoplastic (especially under larger shear rates). 

Metallocene polyethylene has a low proportion of low molecular weight (extractable) components and a low welding and sealing temperature. 
Thus, it is particularly suitable for the food industry.

Polyethylene with multimodal molecular weight distribution
Polyethylene with multimodal molecular weight distribution consists of several polymer fractions, which are homogeneously mixed. 

Such polyethylene types offer extremely high stiffness, toughness, strength, stress crack resistance and an increased crack propagation resistance. 
They consist of equal proportions higher and lower molecular polymer fractions. 

The lower molecular weight units crystallize easier and relax faster. 
The higher molecular weight fractions form linking molecules between crystallites, thereby increasing toughness and stress crack resistance. 

Polyethylene with multimodal molecular weight distribution can be prepared either in two-stage reactors, by catalysts with two active centers on a carrier or by blending in extruders.

*Cyclic olefin copolymers (COC)
Cyclic olefin copolymers are prepared by copolymerization of ethene and cycloolefins (usually norbornene) produced by using metallocene catalysts. 
The resulting polymers are amorphous polymers and particularly transparent and heat resistant.

*Polar ethylene copolymers
The basic compounds used as polar comonomers are vinyl alcohol (Ethenol, an unsaturated alcohol), acrylic acid (propenoic acid, an unsaturated acid) and esters containing one of the two compounds.

Ethylene copolymers with unsaturated alcohols
Ethylene/vinyl alcohol copolymer (EVOH) is (formally) a copolymer of PE and vinyl alcohol (ethenol), which is prepared by (partial) hydrolysis of ethylene-vinyl acetate copolymer (as vinyl alcohol itself is not stable). 

However, typically EVOH has a higher comonomer content than the VAC commonly used.
EVOH is used in multilayer films for packaging as a barrier layer (barrier plastic). 

As EVOH is hygroscopic (water-attracting), it absorbs water from the environment, whereby it loses its barrier effect. 
Therefore, it must be used as a core layer surrounded by other plastics (like LDPE, PP, PA or PET). 
EVOH is also used as a coating agent against corrosion at street lights, traffic light poles and noise protection walls.

*Ethylene/acrylic acid copolymers (EAA)
Copolymer of ethylene and unsaturated carboxylic acids (such as acrylic acid) are characterized by good adhesion to diverse materials, by resistance to stress cracking and high flexibility.

However, they are more sensitive to heat and oxidation than ethylene homopolymers. 
Ethylene/acrylic acid copolymers are used as adhesion promoters.

If salts of an unsaturated carboxylic acid are present in the polymer, thermo-reversible ion networks are formed, they are called ionomers. 
Ionomers are highly transparent thermoplastics which are characterized by high adhesion to metals, high abrasion resistance and high water absorption.

Ethylene copolymers with unsaturated esters
If unsaturated esters are copolymerized with ethylene, either the alcohol moiety may be in the polymer backbone (as it is the case in ethylene-vinyl acetate copolymer) or of the acid moiety (e. g. in ethylene-ethyl acrylate copolymer). 

Ethylene-vinyl acetate copolymers are prepared similarly to LD-PE by high pressure polymerization. 
The proportion of comonomer has a decisive influence on the behaviour of the polymer.

The density decreases up to a comonomer share of 10% because of the disturbed crystal formation. 
With higher proportions it approaches to the one of polyvinyl acetate (1.17 g/cm3).

Due to decreasing crystallinity ethylene vinyl acetate copolymers are getting softer with increasing comonomer content. 
The polar side groups change the chemical properties significantly (compared to polyethylene) weather resistance, adhesiveness and weldability rise with comonomer content, while the chemical resistance decreases. 

Also mechanical properties are changed: stress cracking resistance and toughness in the cold rise, whereas yield stress and heat resistance decrease. 
With a very high proportion of comonomers (about 50%) rubbery thermoplastics are produced (thermoplastic elastomers).

Ethylene-ethyl acrylate copolymers behave similarly to ethylene-vinyl acetate copolymers.

CROSS-LINKED POLYETHYLENE:
A basic distinction is made between peroxide crosslinking (PE-Xa), silane crosslinking (PE-Xb), electron beam crosslinking (PE-Xc) and azo crosslinking (PE-Xd)

*Peroxide crosslinking (PE-Xa): 
The crosslinking of polyethylene using peroxides (e. g. dicumyl or di-tert-butyl peroxide) is still of major importance. 
In the so-called Engel process, a mixture of HDPE and 2% peroxide is at first mixed at low temperatures in an extruder and then crosslinked at high temperatures (between 200 and 250 °C).

The peroxide decomposes to peroxide radicals (RO•), which abstract (remove) hydrogen atoms from the polymer chain, leading to radicals. 
When these combine, a crosslinked network is formed.
The resulting polymer network is uniform, of low tension and high flexibility, whereby it is softer and tougher than (the irradiated) PE-Xc.

*Silane crosslinking (PE-Xb): 
In the presence of silanes (e.g. trimethoxyvinylsilane) polyethylene can initially be Si-functionalized by irradiation or by a small amount of a peroxide.
Later Si-OH groups can be formed in a water bath by hydrolysis, which condense then and crosslink the PE by the formation of Si-O-Si bridges. 
Catalysts such as dibutyltin dilaurate may accelerate the reaction.

*Irradiation crosslinking (PE-Xc): 
The crosslinking of polyethylene is also possible by a downstream radiation source (usually an electron accelerator, occasionally an isotopic radiator). 
PE products are crosslinked below the crystalline melting point by splitting off hydrogen atoms. 

β-radiation possesses a penetration depth of 10 mm, ɣ-radiation 100 mm. 
Thereby the interior or specific areas can be excluded from the crosslinking.

However, due to high capital and operating costs radiation crosslinking plays only a minor role compared with the peroxide crosslinking.
In contrast to peroxide crosslinking, the process is carried out in the solid state. 
Thereby, the cross-linking takes place primarily in the amorphous regions, while the crystallinity remains largely intact.

*Azo crosslinking (PE-Xd): 
In the so-called Lubonyl process polyethylene is crosslinked preadded azo compounds after extrusion in a hot salt bath.

*Chlorination and sulfochlorination
Chlorinated Polyethylene (PE-C) is an inexpensive material having a chlorine content from 34 to 44%. 
It is used in blends with PVC because the soft, rubbery chloropolyethylene is embedded in the PVC matrix, thereby increasing the impact resistance.

It also increases the weather resistance. 
Furthermore, it is used for softening PVC foils, without risking the migrate of plasticizers. 

Chlorinated polyethylene can be crosslinked peroxidically to form an elastomer which is used in cable and rubber industry.
When chlorinated polyethylene is added to other polyolefins, it reduces the flammability.
Chlorosulfonated PE (CSM) is used as starting material for ozone-resistant synthetic rubber.

BIO-BASED POLYETHYLENE:
Bioplastics and Renewable Polyethylene
Braskem and Toyota Tsusho Corporation started joint marketing activities to produce polyethylene from sugarcane. 
Braskem will build a new facility at their existing industrial unit in Triunfo, Rio Grande do Sul, Brazil with an annual production capacity of 200,000 short tons (180,000,000 kg), and will produce high-density and low-density polyethylene from bioethanol derived from sugarcane.

NOMENCLATURE AND GENERAL DESCRIPTION OF THE PROCESS OF POLYETHYLENE:
The name polyethylene comes from the ingredient and not the resulting chemical compound, which contains no double bonds. 
The scientific name polyethene is systematically derived from the scientific name of the monomer.

The alkene monomer converts to a long, sometimes very long, alkane in the polymerization process.
In certain circumstances it is useful to use a structure-based nomenclature; in such cases IUPAC recommends poly(methylene) (poly(methanediyl) is a non-preferred alternative).

The difference in names between the two systems is due to the opening up of the monomer's double bond upon polymerization.
The name is abbreviated to PE. 

In a similar manner polypropylene and polystyrene are shortened to PP and PS, respectively. 
In the United Kingdom and India the polymer is commonly called polythene, from the ICI trade name, although this is not recognized scientifically.

A SHORT HISTORY OF POLYETHYLENE:
We have Reginald Gibson and Eric Fawcett to thank for the invention of polyethylene. 
In the early 1930s, they experimented with ethylene and benzaldehyde. 
The reaction that came from this is what we now know as polyethylene. 

While the original methodology was pretty rudimental, today we have outlined processes, the right equipment, and safety guidelines to guide manufacturers in the creation of polyethylene.

A few years later in 1936, Imperial Chemical Industries filed a patent for polyethylene. 
Its adaptability made it a popular plastic to work with and more uses and processes for creating it emerged. 

Another chemist by the name of Karl Ziegler came along and figured out a way to specifically combine high-density polyethylene (HDPE), which is still an important process used nowadays. 
Even a portion of the process is named after him, the Ziegler-Natta catalyst or Ziegler-Natta polymerization—Natta being another chemist who played a part in the development.

POLYETHYLENE CHEMICAL FORMULA:
Time to think back to chemistry class. Polyethylene’s chemical formula is (C2H4)n. 
This means it has two carbon atoms that are linked to four hydrogen atoms. 
The “n” at the endpoints to the chain structure that polyethylene takes on. 

HOW POLYETHYLENE IS MADE:
As its name suggests, polyethylene is made out of ethylene, which results from both crude oil and natural gas. 
Ethylene needs a catalyst in order to transform into polyethylene, whereas different types of polymerization create other well-known plastics, like nylon. 

One of the most common polymerization processes is called addition polymerization. 
Also known as chain reaction polymerization, there are several forms or subtypes that fall under this category, including coordination. 

What happens is that a catalyst (such as the famous Ziegler-Natta catalyst) is introduced and monomers will react and link up to create chains. 
This reaction creates the plastic.

Free radical polymerization, on the other hand, uses a radical to break the double bond between the two carbon atoms. 
This reaction leaves one side open on the molecule for bonding, and another molecule will slide right in and link up—creating the polymer chain. 

After these processes take place, you can shape polymer into long threads or filaments. 
These will be chopped into pellets and then passed along for processing into objects we’re familiar with. 

TESTED POLYETHYLENE SYNTHESIS:
Now if, for some strange reason, you'd actually like to make high density polyethylene the way it's made in the lab, we have two procedures for you in the same pdf file. 
They use two different transition metal catalysts to give two different linear and almost linear Polyethylene samples. 

NMR Spectra of LDPE
So you have a sample of what you think is polyethylene, and specifically the low-density version. 
Maybe you even made it yourself. 

How can you be sure that's what it is? 
You decide to get an NMR spectrum or two. 

But of course, you have to have an actual spectrum of this material to compare it to.
So here's a 1H spectrum of LDPE and and here's its 13C spectrum.

PHYSICAL and CHEMICAL PROPERTIES of POLYETHYLENE:
Chemical formula: (C2H4)n
Density: 0.88–0.96 g/cm3
Melting point: 115–135 °C (239–275 °F; 388–408 K)
Solubility in water: Not soluble
log P: 1.02620
Magnetic susceptibility (χ): −9.67×10−6 (HDPE, SI, 22 °C)
Thermochemistry:
Std enthalpy of formation (ΔfH⦵298): −28 to −29 kJ/mole
Heat of combustion, higher value (HHV): 650-651 kJ/mole, 46 MJ/kg
Tensile Strength: 0.20 - 0.40 N/mm²
Notched Impact Strength: no break Kj/m²
Thermal Coefficient of expansion: 100 - 220 x 10-6
Max Cont Use Temp: 65 °C

Density: 0.944 - 0.965 g/cm3
Appearance Form: powder
Color: light graywhite
Odor: odorless
Odor Threshold: Not applicable
pH: No data available
Melting point/freezing point:
Melting point/range: 100 - 120 °C
Initial boiling point and boiling range: 48 - 110 °C at 12 hPa
Flash point: No data available
Evaporation rate: No data available
Flammability (solid, gas): May form combustible dust concentrations in air.
Upper/lower flammability or explosive limits: No data available
Vapor pressure: No data available

Vapor density: No data available
Relative density: 0,97 g/cm³ at 25 °C
Water solubility: at 20 °C insoluble
Partition coefficient: n-octanol/water: No data available
Autoignition temperature: No data available
Decomposition temperature: No data available
Viscosity 
Viscosity, kinematic: No data available
Viscosity, dynamic: No data available
Explosive properties: No data available
Oxidizing properties: No data available

Other safety informatio: No data available
-Flexible, translucent/waxy, weatherproof, 
good low temperature toughness (to -60'C), 
easy to process by most methods, low cost, 
good chemical resistance.
Tensile Strength: 0.20 - 0.40 N/mm²
Notched Impact Strength: no break Kj/m²
Thermal Coefficient of expansion: 100 - 220 x 10-6
Max Cont Use Temp: 65 oC
Density: 0.944 - 0.965 g/cm3

FIRST AID MEASURES of POLYETHYLENE:
-Description of first-aid measures:
*If inhaled:
After inhalation: 
Fresh air.
*In case of skin contact: 
Take off immediately all contaminated clothing. 
Rinse skin with water/ shower.
*In case of eye contact:
After eye contact: 
Rinse out with plenty of water. 
Remove contact lenses.
*If swallowed:
After swallowing: 
Make victim drink water (two glasses at most). 
Consult doctor if feeling unwell.

ACCIDENTAL RELEASE MEASURES of POLYETHYLENE:
-Personal precautions, protective equipment and emergency procedures:
-Environmental precautions:
Do not let product enter drains.
-Methods and materials for containment and cleaning up:
Cover drains. 
Collect, bind, and pump off spills. 
Observe possible material restrictions.
Take up dry. 
Dispose of properly. 
Clean up affected area. 

FIRE FIGHTING MEASURES of POLYETHYLENE:
-Extinguishing media:
Suitable extinguishing media:
Use extinguishing measures that are appropriate to local circumstances and the surrounding environment.
Unsuitable extinguishing media:
For this substance/mixture no limitations of extinguishing agents are given.

EXPOSURE CONTROLS/PERSONAL PROTECTION of POLYETHYLENE:
-Control parameters:
Ingredients with workplace control parameters:
-Exposure controls:
Personal protective equipment:
*Eye/face protection:
Use equipment for eye protection.
Safety glasses.
*Skin protection:
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min
Splash contact:
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min
*Respiratory protection:
Recommended Filter type: Filter type P1
-Control of environmental exposure:
Do not let product enter drains.

HANDLING and STORAGE of POLYETHYLENE:
-Conditions for safe storage, including any incompatibilities:
*Storage conditions:
Tightly closed. 
Dry.
*Storage stability
Recommended storage temperature: -20 °C

STABILITY and REACTIVITY of POLYETHYLENE:
-Reactivity: 
No data available
-Chemical stability: 
The product is chemically stable under standard ambient conditions (room temperature) .
-Possibility of hazardous reactions: 
No information available
-Conditions to avoid: 
No information available