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WHAT IS PVC?

Poly(vinyl chloride), commonly abbreviated PVC, is the third-most widely producedplastic,

afterpolyethylene andpolypropylene. PVC is used inconstruction because it is moreeffective than traditional materials such as copper, iron or wood in pipe and profileapplications. It can be made softer and more flexible by the addition ofplasticizers, themost widely used beingphthalates.In this form, it is also used in plumbing, electrical cableinsulation, inflatable products and many applications in which it replaces rubber.

Pure poly(vinyl chloride) is a white, brittle solid. It is insoluble in alcohol, but slightly solubleintetrahydrofuran.

PVC is a thermoplastic made of 57% chlorine(derived from industrial grade salt) and 43% carbon

(derived predominantly from oil / gas via ethylene). Itis less dependent than other polymers on crude oil ornatural gas, which are nonrenewable, and hence canbe regarded as a natural resource saving plastic, incontrast to plastics such as PE, PP, PET and PS,which are totally dependent on oil or gas. This

chlorine gives to PVC excellent fire resistance.

HISTORY

Man has worked hard from the earliest times todevelop synthetic materials which would offer benefits notfound in the natural products around him.

PVC is one of the oldest synthetic materials with thelongest history in industrial production. Its early history is ofmultiple and accidental discovery in different places atdifferent times as well as unsuccessful quests forcommercial application.

PVC_pellets_(Ineos)WEB

Alchemists tried to developnew materials

http://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Polyethylenehttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Plasticizerhttp://en.wikipedia.org/wiki/Phthalateshttp://en.wikipedia.org/wiki/Tetrahydrofuranhttp://en.wikipedia.org/wiki/Tetrahydrofuranhttp://en.wikipedia.org/wiki/Phthalateshttp://en.wikipedia.org/wiki/Plasticizerhttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/Polyethylenehttp://en.wikipedia.org/wiki/Plastic

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Early researchers accidentally discovered PVC on atleast two occasions in the 19th century. The first, in 1838, wasby the French physicist and chemist Henri Victor Regnault andthe second in 1872 by the German Eugen Baumann. On bothoccasions, the polymer appeared as a white solid inside flasks

of the newly discovered vinyl chloride gas that had been leftexposed to sunlight. The material was difficult to work with andno one mastered the challenge of commercial applications.

In 1913, German inventor Friedrich Heinrich AugustKlatte took out a patent on PVC. His method usedpolymerization of vinyl chloride with sunlight.The most significant breakthrough occurred in the UnitedStates when the company BFGoodrich hired the industrialscientist Waldo Semon to develop a synthetic replacement for

the increasingly costly natural rubber. His experiments againproduced polyvinyl chloride. However, the material was threatened by the recession in the 1920sand it was under threat of abandonment that Semon conceived the idea of PVC as a waterresistant coating for fabrics. Sales took off quickly with a rapidly expanding product range. Demandaccelerated again during the Second World War, when PVC quickly replaced traditional material toinsulate wiring on military ships.

During the 1950's many more companies started to produce PVC and volumes increaseddramatically around the world. Developers quickly found further, innovative uses through thedecade and refined methods to enhance durability, opening the door to applications in the building

trades. By the middle of the 20th century, five companies were producing PVC, and ground-breaking uses for PVC, or vinyl as it is also known, continued to be found during the 1960s. Avinyl-based latex was used on inflatable structures and fabric coatings, and at the same time,methods for improving PVC's durability were developed, allowing applications in the buildingindustry.

PVC products rapidly became essential to the construction industry; the plastic'sresistance to light, chemicals and corrosion made it the best option for building applications.Improvement made to the materials resistance to extreme temperatures, allowed for PVC to betransporting water to thousands of homes and industries. By the 1980s, twenty companies wereproducing PVC. Today, PVC is the third largest-selling commodity plastic in the world afterpolyethylene and polypropylene. PVC's low cost, excellent durability and processability, make it thematerial of choice for dozens of industries such as health care,IT, transport, textiles andconstruction.

Henry Victor Regnault discovered PVC

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HOW IS PVC MADE ?

The chemical process for making PVC involves taking the simplest unit, called themonomer, and linking these monomer molecules together in the polymerisation process. Long

molecular chains are formed called polymers (which are also called macromolecules).

This is the case for PVC, which is made from vinyl chloride monomer known usually by itsinitials VCM through polymerisation. Some monomers exist in the form of reactive gaseouschemical substances, and some of these may cause health hazards when in direct contact withhumans. In these cases they are manufactured and processed under strict control for health, safetyand environmental protection. On the other hand, polymers such as PVC, which are manufacturedfrom monomers through polymerisation, are solid and chemically stable substances, therefore donot affect human health. VCM, which is the raw material for PVC, is a gas at ambient temperaturebut is usually stored in liquid form under pressure. Ethylene and chlorine are raw materials for

PVC. Upstream industries are those that provide these materials and include producers of basicpetrochemicals (sometimes known as feedstocks), which supply ethylene, and the chlor-alkali(caustic soda) industry, which supplies chlorine.

By thermal cracking of naphtha or natural gas, the basic petrochemical industrymanufactures ethylene and propylene, etc. Naphtha is mainly supplied from the petroleum refineryindustry, which uses crude oil as raw material. The chlor-alkali industry produces caustic soda,chlorine and hydrogen via electrolysis using industrial grade salt as main raw material.

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At a first stage in the PVC production process ethylene and chlorine are combined to

produce an intermediate product called ethylene dichloride; this is then transformed into vinylchloride, the basic building block of polyvinyl chloride or PVC. The process of `polymerisation' linkstogether the vinyl chloride molecules to form chains of PVC. The PVC produced in this way is in

the form of a white powder. This is not used alone, but blended with other ingredients to giveformulations for a wide range of products.

Most commodity plastics have carbon and hydrogen as their main component elements.PVC differs by containing chlorine (around 57 per cent by weight) as well as carbon and hydrogen.The presence of chlorine in the molecule makes PVC particularly versatile because it makes itcompatible with a wide range of other materials. The chlorine content also helps to make PVCflame retardant. It can also be used as a `marker' to distinguish PVC in automatic sorting systemsfor plastics recycling. PVC formulations can be shaped by a variety of techniques and, using verylittle energy, made into the final product form. PVC polymer is chemically stable, neutral and non-

toxic. PVC formulations have a wide range of applications including the most sensitive, such asmedical equipment, plus construction, automotive and electrical cabling.

THE PVC PRODUCTION PROCESS

How PVC is manufactured?

The suspension polymerisation process is most widely used process to manufacture PVC.

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First, the raw material VCM is pressurised and liquefied, and then fed into thepolymerisation reactor, which contains water and suspending agents in advance. Through high-speed agitation within the reactor, small droplets of VCM are obtained. Next, the initiator forpolymerisation is fed into the reactor, and PVC is produced by reaction under a few bar at 40 -60C. PVC obtained through suspension polymerisation is suspended in water as particles of50~200 m diameter (in slurry form). Thereafter the slurry discharged from the polymerisationreactor is stripped of residual monomer, dehydrated, dried and the particle size controlled byscreening to yield PVC in the form of a white powder. The un-reacted VCM is entirely recoveredthrough the stripping process, and after purification, recycled as raw material for reuse in thisprocess. PVC resin produced via this suspension process is referred to within th e industry usingthe abbreviation S-PVC.

Emulsion polymerisation and bulk polymerisation are alternative, much less extensivelyemployed, technologies to manufacture PVC. Emulsion polymerisation produces finer resin grades

having much smaller particles, which are required by certain applications. This type of resin issometimes called paste PVC and referred to within the industry using the abbreviation P-PVC todistinguish it from S-PVC.

USES OF POLYVINYL CHLORIDE (PVC)

PVC, or polyvinyl chloride, is a type of plasticused in numerous industries. It is durable,inexpensive and resistant to heat, water andchemicals. Additives such as lubricants, heatstabilizers, plasticizers, impact modifiers,fillers, biocides, smoke suppressors and UVstabilizers enhance its durability and make itsuitable for a variety of constructionapplications.

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ClothingPVC plastic is manipulated to create a leather-

like material called rexine. This type of imitation leatheris used to make jackets, shoes, trousers andupholstery. PVC clothing is cheaper than latex, leather

and rubber, and is widely available. PVC fabric iswaterproof, resistant to chemicals, long-lasting andflexible, and has a natural sheen to it--allowingdesigners to create new and innovative styles at highlyaffordable prices.

Pipes

According to "PVC Pipe & Fittings: Underground

Solutions for Water and Sewer Systems in North America,"

approximately half of all PVC plastic is used in the

manufacture of pipes, which are employed in industrial and

municipal applications. PVC pipes are strong, lightweight

and low-reactive, making them well-suited in sanitary,

underground-wiring and water-distribution applications.PVC water pipes do not wear, rot or rust, and are a

dependable and affordable material for potable-water

piping. There are different types of PVC pipes, including

Schedule 40, Schedule 80, Schedule 120, CPVC

(chlorinated polyvinyl chloride) and Gray Schedule 40.

PVC fabric is waterproof, making it suitable forscuba-diving gear. (two scuba divers image by

Janet Wall from Fotolia.com)

PVC water pipes don't rot or rust. (pvc imageby pearlguy from Fotolia.com)

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Electrical Wires

PVC plastic is commonly used to form the insulating

material on electrical wires. It is affordable and

resistant to heat, and it offers excellent abrasion and

solder resistance. A PVC conductor jacket insulates

electrical wires and offers additional protection to

unshielded cables. PVC is fire retardant, chemical- and

oil-resistant, mechanically stable, impact resistant, and

elastic and, because of its biocides, prevents the

growth of microbial (harmful, disease-causing

pathogens). Single-core flexible wires are copper

conductors that are coated with a thin jacket of

insulating PVC plastic. PVC is also used as a coatingfor tinned copper, bare copper, aluminum and fiber-

optic wires.

Bottles

PVC plastic is used to manufacture bottles that have

applications in a wide range of industries. PVC is strongly

resistant to harmful organic solids, strong bases and strongacids. Bottles made from PVC are an excellent choice for

vinegar, mineral oil, shampoo, salad dressing and

cosmetics, all because of their resistance to chemicals,

heat, oil and grease.

PVC is an excellent way to insulate electricalwires. (electricity wire image by jeancliclacfrom Fotolia.com

PVC's resistance to chemicals makes it a

good choice for food or toiletry bottles.(plastic bottles image by Oleg Ivanov fromFotolia.com)

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Other Uses

Other uses of PVC include medical tubing, vinyl

fencing, and railing and decking, PVC window

frames, meat/deli wrap, shrink wrap, flexible

packaging, blood bags, resilient flooring, vinyl

paneling, phonograph records, carpet backing, traffic

cones, garden hoses and vinyl gutters.

POLYVINYL CHLORIDE ENVIRONMENTAL IMPACTS

1. The effects of Vinyl and dioxinAmong the most important by-products of the PVC lifecycle are dioxin and a large group of

structurally and toxicologically related compounds, collectively called dioxins. Dioxins are never

manufactured intentionally but are formed accidentally whenever chlorine gas is used or chlorine-

based organic chemicals are burned or processed under reactive conditions.

Dioxins are true global pollutants, now found in the tissues of whales in the deep oceans,polar bears in the high Arctic, and every human being on earth. Human infants receive

particularly high doses orders of magnitude greater than those of the average adult

because dioxins cross the placenta easily and concentrate in breast milk.

Dioxin is the most potent synthetic carcinogen ever tested in laboratory animals and is aknown human carcinogen.

Human development, reproduction, and the immune and endocrine systems are highlysensitive to dioxin, which causes health damage and functional impairment at infinitesimallylow doses (in the low parts per trillion, or ppt). Toxicological studies have not been able to

establish a threshold dose below which dioxin has no biological impact.

Remember vinyl records? (vinyl record imageby Warren Millar from Fotolia.com)

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2. Effects of Phthalate plasticizersIn its pure form, PVC is rigid and brittle. To make flexible vinyl products, such asfloor tiles, roofing

materials, and wall coverings, plasticizers must be added to PVC in large quantities up to 60

percent of the final product by weight. The dominant group of plasticizers used in vinyl is a class of

compounds called phthalates, which pose considerable health and environmental hazards. Vinyl is

the7 only major building product using phthalates extensively, accounting for about 90 percent of

total phthalate consumption. More than 5 million tons of phthalates are used in vinyl every year.

Phthalates have become global pollutants that are moderately persistent and moderatelybioaccumulative under some conditions. They can be found in the water of the deep

oceans, air in remote regions, and the tissues and fluids of humans. Body burdens of some

phthalates have recently been found to be surprisingly high in the bodies of the general

U.S. population. Infants and toddlers are subject to exposures several times higher thanthose of the average adult.

Millions of pounds per year of phthalates are released into the environment during theformulation and molding of vinyl products. Phthalates are also released when vinyl is

disposed of in landfills or incinerators or when PVC products burn accidentally. More than

80 million tons of phthalates are estimated in the stock of PVC products now in use in

buildings and other applications.

Phthalates are not chemically bonded to the plastic but are mixed with the polymer duringformulation. They therefore leach out of the plastic over time into air, water, or other

substances with which vinyl comes in contact.

Phthalates cause a range of health effects. Phthalates used in PVC have been found todamage the reproductive system, causing suppressed ovulation, infertility, reduced sperm

count, testicular damage, and abnormal development and function of the testes and male

reproductive tract in laboratory animals, in which they are also carcinogens.

3. Effects of Lead and other stabilizersBecause PVC catalyzes its own decomposition, metal stabilizers are added to vinyl for construction

and other extended-life applications.

Common PVC additives that are particularly hazardous are lead, cadmium, and organotins,with global consumption of each by vinyl estimated in the thousands of tons per year.

Because metals do not degrade in the environment, all three of the major PVC stabilizershave become global pollutants.

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Lead is a highly potent developmental toxicant, damaging brain development and reducingthe cognitive ability and IQ of children, even in infinitesimal doses. Cadmium is a potent

neurotoxin and carcinogen, and organotins can suppress immunity and disrupt the

endocrine system.

Metal stabilizers are released from vinyl products when they are formulated, used, anddisposed. Releases of lead stabilizers from interior vinyl building products have beendocumented. Metals cannot be destroyed by incineration but are released entirely into the

environment via air emissions or ash residues. Trash incinerators are a dominant source of

lead and cadmium pollution, and PVC contributes a significant portion of the feed of these

metalsincluding an estimated 45,000 tons of lead each yearto incinerators.

Accidental fires are also major potential sources of lead, cadmium, and organotinsreleases. In a fire, metals in PVC will be released to the environment. An astounding 3.2

million tons of lead are present in the current stock of PVC in use. Potential lead releases

from this stored PVC must be viewed as a major potential health hazard.

4. Effects to Indoor air qualityFlexible vinyl products appear to contribute to the health hazards of poor indoor air quality by

releasing phthalates and facilitating the growth of hazardous molds.

The phthalates in PVC are released into the building environment. Phthalate levels inindoor air for buildings with PVC are typically many times higher than those for outdoor air.

Phthalate accumulation in suspended and sedimented indoor dusts is particularly high, with

concentrations in dust as high as 1,000 parts per million (ppm).

Preliminary evidence indicates that PVC-related phthalate exposure may be linked toasthma. In laboratory animals, metabolites of phthalates used in vinyl cause asthma-like

symptoms through a well-described inflammatory mechanism. Three separate

epidemiological studies have found that human exposure to PVC in buildings causes

significantly elevated risks of asthma and other pulmonary conditions, including bronchial

obstruction, pneumonia, prolonged cough, wheezing, and irritation of the nasal passages

and eyes.

Metal stabilizersparticularly lead, cadmium, and organotinscan also be released fromvinyl products. Lead has been found to be released into air from vinyl window blinds and

into water from PVC pipes. Toxicological effects of these substances include

developmental, neurological, and reproductive damage.

Because vinyl wall coverings form a barrier impermeable to moisture, they encourage thegrowth of molds on wall surfaces beneath the vinyl particularly in buildings where air

conditioning or heating systems produce significant temperature and humidity differentials

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between rooms and wall cavities. Some molds that grow beneath vinyl produce toxic

substances that are released into indoor air. Numerous liability suits are active on the link

between vinyl-produced molds and respiratory and neurological symptoms among exposed

populations. Vinyl has been cited as the interior building material most likely to facilitate the

growth of these molds.

5. Effects Ethylene Dichloride (EDC)It is an intermediate chemical in the production of PVC resin.

Because EDC possible/probable human carcinogen, exposure to high levels is also knownto damage the heart, central nervous system, liver, kidneys and lungs in humans. Health

effects from repeated exposure to low doses of the chemical are not known.

Ethylene dichloride is persistent in both air and water, it may travel long distances once it isin the air and has been found in urban and rural air samples, in indoor samples taken near

hazardous waste disposal sites and in surface water, ground water and drinking water.

Ingestion of contaminated drinking water is thought to be a significant route of exposure for

4 to 5% of the US population.

6. Effects on Vinyl Chloride Monomer (VCM)Vinyl chloride is a colourless flammable gas, made by subjecting ethylene dichloride to a

cracking process. It is the basic building block of PVC. It is transported in liquid form either underpressure or refrigerated, by road rail and sea.

Vinyl chloride is classified as a human carcinogen by both the International Agency forResearch on Cancer and the US EPA. It is one of the top twenty hazardous substances on

the EPA/ATSDR priority list.

Liver cancer is a well established risk from chronic exposure and it has also been found toaffect immunological, neurological, reproductive and development systems.

The primary routes of potential human exposure to vinyl chloride are via inhalation andcontact with the skin. People living in the vicinity of emission sources mainly PVC

factories - are potentially exposed by breathing contaminated air. According to the US

Department of Health and Human Services new car owners are potentially polymers in the

car interior. In the United States vinyl chloride has been found in concentrations as high as

380 g/l in ground water and 10g/l in drinking water. This figure for drinking water is five

times the maximum contaminant level for vinyl chloride determined by the US EPA under

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the safe drinking water act. Workers in the PVC industry face additional risks.

Occupational exposures generally occur as vinyl chloride monomer is piped to storage or

transportation, during maintenance or during polymerisation to form PVC when vinyl

chloride escapes into the air.

As well as being highly toxic in its own right, VCM production causes other toxic emissionsand residues. For example, for every 100,000 tonnes of vinyl chloride output at the NorskHydro plant in Stenungsund, Sweden, by-products include more than 2,700 tonnes of

organochlorines (including dioxins).