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Encyclopedia > Polyvinylchloride
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Polyvinyl chloride (PVC) is a widely-used plastic. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Globally, over 50% of PVC manufactured is used in construction. As a building material PVC is cheap, and easy to assemble. In recent years, PVC has been replacing traditional building materials such as wood, concrete and clay in many areas. Despite appearing to be an ideal building material, PVC has high environmental and human health costs.


Polyvinyl chloride is produced from its monomer, vinyl chloride (chemical formula CH2=CHCl). PVC is a hard plastic that is made softer and more flexible by the addition of phthalates (plasticizers).


There are many uses for PVC including vinyl siding, gramophone records (hence the ones made of this material are sometimes called vinyl records) pipe/plumbing/conduit fixtures, bean bags; and, in its soft form, for clothing, upholstery (car seats), etc.

Contents

History

Polyvinyl chloride was accidentally discovered on at least two occasions in the 19th century, first in 1838 by Henri Victor Regnault and in 1872 by Eugen Baumann. On both occasions, the polymer appeared as a white solid inside flasks of vinyl chloride that had been left exposed to sunlight. In the early 20th century, the Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim-Elektron both attempted to use PVC in commercial products, but difficulties in processing the rigid, sometimes brittle polymer blocked their efforts.


In 1926, Waldo Semon of B.F. Goodrich developed a method to plasticize PVC by blending it with various additives. The result was a more flexible and more easily processed material that soon achieved widespread commercial use.


Dangers of PVC

Most vinyl products are believed to be generally harmless when used properly. However, some of the additives and softeners leech out of certain vinyl products. Even though soft PVC toys have been made for babies for years, studies find that these additives leech out of soft toys into the mouths of the children chewing on them. Vinyl IV bags used in neo-natal intensive care units have also been shown to leach DEHP (di-2-ethyl hexyl phthalate), a phthalate additive. In Europe, phthalate additives in PVC toys for children under the age of three have been banned and in the USA, most companies have voluntarily stopped manufacturing PVC toys for this age group or have eliminated the phthalates. However, alternative softeners have not been properly tested to determine whether they are safe. Other vinyl products like brand new car interiors, shower curtains, and flooring, to name a few, initially release chemical gases into the air. Some studies indicate that this outgassing of additives may contribute to health complications, but the information on this is preliminary and needs further study.


According to some medical studies, the plasticizers added to PVC may cause chronic conditions such as Raynaud's syndrome, scleroderma, cholangiocarcinoma, angiosarcoma, brain cancer and acroosteolysis.


In the late 1960's, Dr. John Creech, and Dr. Maurice Johnson, were the first to clearly link and recognize the carcinogenicity of vinyl chloride monomer to humans; workers in the polyvinyl chloride polymerization section of a B.F. Goodrich plant near Louisville, Kentucky, were diagnosed with liver angiosarcoma, a rare disease. Since that time, studies of PVC workers in Australia, Italy, Germany, and the U.K. have all associatied occupational cancers with exposure to vinyl chloride.


The environmentalist group Greenpeace has advocated the global phase-out of PVC because dioxin is produced as a byproduct of vinyl chloride manufacture.


In 2004, a joint Swedish-Danish research team found a very strong link between allergies in children and the phthalates DEHP and BBzP, commonly used in PVC.


The European Industry, however, has found a method to avoid dioxin production recently. Instead of using trouble-making softeners and additives, they use palm oil and high purity PVC material. In the end, however, it is futile because it's so expensive, and the performance is not as good as the original method.


Resin identification code

The symbol for polyvinyl chloride developed by the Society of the Plastics Industry so that items can be labelled for easy recycling is


The Unicode character U+2675 (HTML ♵).


See also

External links

  • Polyvinyl Chloride - Poisonous Plastic (http://www.ejnet.org/plastics/pvc/)
  • Health impacts of PVC and guides to alternatives - Healthy Building Network (http://www.healthybuilding.net/)
  • The Vinyl Institute (http://www.vinylinfo.org/index.html)
  • Vinyl.org (Vinyl Council of Canada) (http://www.vinyl.org)
  • The European PVC Portal (European Council of Vinyl Manufacturers) (http://www.ecvm.org)
  • Uni-Bell PVC Pipe Association (http://www.uni-bell.org)
  • Hydro PVC (http://www.hydropolymers.com/en/products/pvc/index.html)
  • The Association between Asthma and Allergic Symptoms in Children and Phthalates in House Dust: A Nested Case-Control Study (http://ehp.niehs.nih.gov/members/2004/7187/7187.html)

  Results from FactBites:
 
Process for the preparation of large surface area, finely divided precipitated calcium carbonate and filled polymeric ... (4053 words)
A filled polyvinylchloride polymer composition which comprises polyvinylchloride; about 9 phr of impact modifier; and about 4 phr of precipitated calcium carbonate having an average specific surface area of from about 75 m.sup.2 /g to about 85 m.sup.2 /g and having a coating thereon derived from a salt of a fatty acid.
Such polyvinylchloride polymer compositions filled with the fatty acid derivative coated precipitated calcium carbonate of this invention have enhanced properties of decreased shear stress, increased impact strength and an increased output level of polymer per unit of energy consumption without significantly sacrificing the transparency of the composition.
Polyvinylchloride formulations were prepared using a medium low molecular weight polyvinylchloride and a basic formulation suitable for bottle applications with 5 phr of impact modifier and various levels of 10% sodium stearate coated precipitated calcium carbonate having a specific surface area before coating of either 22 m.sup.2 /g or 85 m.sup.2 /g.
WSAVA 2001 - Enteral Feeding Devices: What’s Old, What’s New? (3060 words)
These materials have tended to replace the older polyvinylchloride feeding tubes that tend to stiffen when exposed to digestive juices and are more irritating to patients, necessitating frequent tube replacement.
Polyvinylchloride (Infant Feeding Tube, Argyle Division of Sherwood Medical, St. Louis, MO) or red rubber tubes (Sovereign Feeding Tube, Monoject Division of Sherwood Medical, St. Louis, MO) are the least expensive tubes, although the polyvinylchloride tubes may harden within two weeks of insertion and cause irritation or ulceration of the pharynx or esophagus.
A 5 French polyvinylchloride tube (Infant Feeding Tube, Argyle Division of Sherwood Medical, St. Louis, MO) is introduced into the bowel lumen through the hypodermic needle and is advanced for 20 to 30 cm aborally.
  More results at FactBites »

 
 

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