Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: polyvinyl, or simply vinyl; abbreviated: PVC) is the world’s third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of PVC are produced each year.

PVC comes in rigid (sometimes abbreviated as RPVC) and flexible forms. Rigid PVC is used in construction for pipe, doors and windows. It is also used in making plastic bottles, packaging, and bank or membership cards. Adding plasticizers makes PVC softer and more flexible. It is used in plumbing, electrical cable insulation, flooring, signage, phonograph records, inflatable products, and in rubber substitutes. With cotton or linen, it is used in the production of canvas.

Polyvinyl chloride is a white, brittle solid. It is insoluble in all solvents but swells in the monomer and some chlorinated hydrocarbon solvents.

Production

Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), as shown.

About 80% of production involves suspension polymerization. Emulsion polymerization accounts for about 12%, and bulk polymerization accounts for 8%. Suspension polymerization affords particles with average diameters of 100–180 μm, whereas emulsion polymerization gives much smaller particles of average size around 0.2 μm. VCM and water are introduced into the reactor along with a polymerization initiator and other additives. The contents of the reaction vessel are pressurized and continually mixed to maintain the suspension and ensure a uniform particle size of the PVC resin. The reaction is exothermic and thus requires cooling. As the volume is reduced during the reaction (PVC is denser than VCM), water is continually added to the mixture to maintain the suspension.

PVC may be manufactured from either naphtha or ethylene feedstock

Applications

Pipes

Roughly half of the world’s PVC resin manufactured annually is used for producing pipes for municipal and industrial applications. In the private homeowner market, it accounts for 66% of the household market in the US, and in household sanitary sewer pipe applications, it accounts for 75%. Buried PVC pipes in both water and sanitary sewer applications that are 100 mm (4 in) in diameter and larger are typically joined by means of a gasket-sealed joint. The most common type of gasket utilized in North America is a metal-reinforced elastomer, commonly referred to as a Rieber sealing system.

Electric cables

In a fire, PVC-coated wires can form hydrogen chloride fumes; the chlorine serves to scavenge free radicals and is the source of the material’s fire retardancy. While hydrogen chloride fumes can also pose a health hazard in their own right, it dissolves in moisture and breaks down onto surfaces, particularly in areas where the air is cool enough to breathe, and is not available for inhalation.

Construction

PVC is used in construction because it is more effective than traditional materials, such as copper, iron or wood in pipe manufacturing. It is extensively used in the building industry as a low-maintenance material, particularly in Ireland, the United Kingdom, the United States, and Canada. In the US and Canada, it is known as vinyl or vinyl siding. The material comes in a range of colors and finishes, including a photo-effect wood finish, and is used as a substitute for painted wood, mostly for window frames and sills when installing insulated glazing in new buildings; or to replace older single-glazed windows, as it does not decompose and is weather-resistant. Other uses include fascia, and siding or weatherboarding. This material has almost entirely replaced the use of cast iron for plumbing and drainage, being used for waste pipes, drainpipes, gutters and downspouts. uPVC is known as having strong resistance against chemicals, sunlight, and oxidation from water.

Signs

Polyvinyl chloride is formed in flat sheets in a variety of thicknesses and colors. As flat sheets, PVC is often expanded to create voids in the interior of the material, providing additional thickness without additional weight and minimal extra cost (see closed-cell PVC foamboard). Sheets are cut using saws and rotary cutting equipment. Plasticized PVC is also used to produce thin, colored, or clear, adhesive-backed films referred to simply as vinyl. These films are typically cut on a computer-controlled plotter (see vinyl cutter) or printed in a wide-format printer. These sheets and films are used to produce a wide variety of commercial signage products, including car body stripes and stickers.

Clothin

PVC fabric is water-resistant, used for its weather-resistant qualities in coats, skiing equipment, shoes, jackets, and aprons.

Healthcare

The two main application areas for single-use medically approved PVC compounds are flexible containers and tubing: containers used for blood and blood components, for urine collection or for ostomy products and tubing used for blood taking and blood giving sets, catheters, heart-lung bypass sets, hemodialysis sets etc. In Europe the consumption of PVC for medical devices is approximately 85,000 tons each year. Almost one third of plastic-based medical devices are made from PVC.

Wire rope

PVC may be extruded under pressure to encase wire rope and aircraft cable used for general purpose applications. PVC coated wire rope is easier to handle, resists corrosion and abrasion, and may be color-coded for increased visibility. It is found in a variety of industries and environments both indoor and out.

Other uses

PVC piping is cheaper than metals used in musical instrument making; it is therefore a common alternative when making instruments, often for leisure or for rarer instruments such as the contrabass flute. An instrument that is almost exclusively built from PVC tube is the thongophone, a percussion instrument that is played by slapping the open tubes with a flip-flop or similar. PVC is used as a raw material in automotive underbody coating.

Chlorinated PVC

PVC can be usefully modified by chlorination, which increases its chlorine content to or above 67%. Chlorinated polyvinyl chloride, (CPVC), as it is called, is produced by chlorination of aqueous solution of suspension PVC particles followed by exposure to UV light which initiates the free-radical chlorination.

Health and safety

Degradation

The fungus Aspergillus fumigatus degrades plasticized PVC. Phanerochaete chrysosporium was grown on PVC in a mineral salt agar. Phanerochaete chrysosporium, Lentinus tigrinus, Aspergillus niger, and Aspergillus sydowii can effectively degrade PVC.

Plasticizers

Phthalates, which are incorporated into plastics as plasticizers, comprise approximately 70% of the US plasticizer market; phthalates are by design not covalently bound to the polymer matrix, which makes them highly susceptible to leaching. Phthalates are contained in plastics at high percentages. For example, they can contribute up to 40% by weight to intravenous medical bags and up to 80% by weight in medical tubing. Vinyl products are pervasive—including toys car interiors, shower curtains, and flooring—and initially release chemical gases into the air. Some studies indicate that this outgassing of additives may contribute to health complications, and have resulted in a call for banning the use of DEHP on shower curtains, among other uses.

In 2004 a joint Swedish-Danish research team found a statistical association between allergies in children and indoor air levels of DEHP and BBzP (butyl benzyl phthalate), which is used in vinyl flooring. In December 2006, the European Chemicals Bureau of the European Commission released a final draft risk assessment of BBzP which found “no concern” for consumer exposure including exposure to children.

Lead

Lead had previously been frequently added to PVC to improve workability and stability. Lead has been shown to leach into drinking water from PVC pipes.

In Europe the use of lead-based stabilizers was gradually replaced. The VinylPlus voluntary commitment which began in 2000, saw European Stabiliser Producers Association (ESPA) members complete the replacement of Pb-based stabilisers in 2015.

Vinyl chloride monomer

In the early 1970s, the carcinogenicity of vinyl chloride (usually called vinyl chloride monomer or VCM) was linked to cancers in workers in the polyvinyl chloride industry. Specifically workers in polymerization section of a B.F. Goodrich plant near Louisville, Kentucky, were diagnosed with liver angiosarcoma also known as hemangiosarcoma, a rare disease.^[60] Since that time, studies of PVC workers in Australia, Italy, Germany, and the UK have all associated certain types of occupational cancers with exposure to vinyl chloride, and it has become accepted that VCM is a carcinogen.

Dioxins

PVC produces HCl upon combustion almost quantitatively related to its chlorine content. Extensive studies in Europe indicate that the chlorine found in emitted dioxins is not derived from HCl in the flue gases. Instead, most dioxins arise in the condensed solid phase by the reaction of inorganic chlorides with graphitic structures in char-containing ash particles. Copper acts as a catalyst for these reactions.

Studies of household waste burning indicate consistent increases in dioxin generation with increasing PVC concentrations. According to the EPA dioxin inventory, landfill fires are likely to represent an even larger source of dioxin to the environment. A survey of international studies consistently identifies high dioxin concentrations in areas affected by open waste burning and a study that looked at the homologue pattern found the sample with the highest dioxin concentration was “typical for the pyrolysis of PVC”. Other EU studies indicate that PVC likely “accounts for the overwhelming majority of chlorine that is available for dioxin formation during landfill fires.”

The next largest sources of dioxin in the EPA inventory are medical and municipal waste incinerators. Various studies have been conducted that reach contradictory results. For instance a study of commercial-scale incinerators showed no relationship between the PVC content of the waste and dioxin emissions. Other studies have shown a clear correlation between dioxin formation and chloride content and indicate that PVC is a significant contributor to the formation of both dioxin and PCB in incinerators.

In February 2007, the Technical and Scientific Advisory Committee of the US Green Building Council (USGBC) released its report on a PVC avoidance related materials credit for the LEED Green Building Rating system. The report concludes that “no single material shows up as the best across all the human health and environmental impact categories, nor as the worst” but that the “risk of dioxin emissions puts PVC consistently among the worst materials for human health impacts.”

In Europe the overwhelming importance of combustion conditions on dioxin formation has been established by numerous researchers. The single most important factor in forming dioxin-like compounds is the temperature of the combustion gases. Oxygen concentration also plays a major role on dioxin formation, but not the chlorine content.

Several studies have also shown that removing PVC from waste would not significantly reduce the quantity of dioxins emitted. The EU Commission published in July 2000 a Green Paper on the Environmental Issues of PVC”

A study commissioned by the European Commission on “Life Cycle Assessment of PVC and of principal competing materials” states that “Recent studies show that the presence of PVC has no significant effect on the amount of dioxins released through incineration of plastic waste.”