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Polyvinyl chloride

physical science Maturity 5-7 Next article →

Polyvinyl chloride, often called PVC or vinyl, is a synthetic polymer of plastic. It is the third most widely produced synthetic polymer on Earth. Every year, the world produces about 40 million tons of this material. PVC is a white, brittle solid in its pure form. However, it is very versatile because its physical properties can be changed. This makes it useful for everything from hard construction materials to very soft clothing.

Vinyl Einmalhandschuhe
Vinyl Einmalhandschuhe

Scientists create PVC through a chemical process called polymerization. This process links small units called vinyl chloride monomers (VCM) into long, strong chains. About 80% of all production uses suspension polymerization. In this method, VCM and water are placed into a reactor with an initiator. The initiator is a substance that starts the chemical reaction. The vessel is pressurized and mixed constantly to keep the particles a uniform size. This reaction is exothermic, which means it generates its own heat. Because of this, the reactor must be cooled to manage the temperature.

Vinyl chloride Polymerization V1
Vinyl chloride Polymerization V1

There are different ways to perform this polymerization. Suspension polymerization creates particles with diameters between 100 and 180 micrometers. Emulsion polymerization is another method used for about 12% of production. This method creates much smaller particles, averaging around 0.2 micrometers. Bulk polymerization accounts for the remaining 8% of production. The resulting polymer is linear and very strong. About 57% of the mass of PVC is made of chlorine. This high chlorine content gives PVC different properties than other plastics like polyethylene.

Vinyl chloride Polymerization V1
Vinyl chloride Polymerization V1

Raw PVC is unmodified and requires additives to become useful. These additives are called compounds. Different end products require different ingredients to meet specific needs. Heat stabilizers are essential because raw PVC has poor heat stability. Without them, the material can lose hydrogen chloride (HCl) at temperatures above 70 degrees Celsius. This loss is autocatalytic, meaning the process helps itself continue. Other additives include UV stabilizers, flame retardants, and pigments. These ingredients ensure a window frame lasts a long time or a cable resists burning.

One of the most important additives is the plasticizer. Plasticizers change PVC from a rigid solid into a soft gel. PVC is unique because it can accept very large amounts of these substances. Flexible PVC can contain over 85% plasticizer by mass. The most common plasticizers are phthalates, which are diesters of phthalic acid. Scientists categorize them as high or low molecular weight. Low-molecular-weight phthalates, like DEHP, are being phased out due to health risks. Higher-molecular-weight versions, such as DINP, are generally considered safer alternatives.

Bis(2-ethylhexyl)phthalate
Bis(2-ethylhexyl)phthalate

The history of PVC involves several important discoveries. German chemist Eugen Baumann first synthesized PVC in 1872. He discovered the white solid after a flask of vinyl chloride sat on a shelf for four weeks. In the early 20th century, Ivan Ostromislensky and Fritz Klatte tried to use it commercially. They struggled because the polymer was too rigid and brittle to process easily. In 1926, Waldo Semon and the B.F. Goodrich Company solved this problem. They developed a method to plasticize PVC by blending it with additives. This discovery allowed PVC to be used in many new ways.

Men's black PVC pants 01
Men's black PVC pants 01

Today, PVC is used in many massive industries. About half of the world's PVC production capacity is located in China. The largest single producer is Shin-Etsu Chemical in Japan, which holds a 30% global share. In construction, PVC is vital for pipes, doors, and windows. In the United States, PVC accounts for 66% of the household market for pipes. It is also used for electrical cable insulation because it is a good insulator. In a fire, the chlorine in PVC helps scavenge free radicals, which makes the coating fire-retardant.

Laying sewer hi res (2)
Laying sewer hi res (2)

From music to medicine, PVC is everywhere. It is used to make phonograph records, also known as vinyl records. In hospitals, it is used for intravenous tubing and blood bags. Specifically, the combination of PVC and the plasticizer DEHP was used for blood bags because it stabilizes red blood cells. This helps prevent hemolysis, which is the rupture of red blood cells. We also see PVC in everyday items like flooring, signage, and inflatable products.

12in-Vinyl-LP-Record-Angle
12in-Vinyl-LP-Record-Angle
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🖼️ Images & Media (9)
File:Vinyl chloride Polymerization V1.svg
Vinyl chloride Polymerization V1.svg
File:Plastic degradation material problem - injection molding discoloration or plastic element yellowing with age.jpg
Plastic degradation material problem -...
File:Bis(2-ethylhexyl)phthalate.svg
Bis(2-ethylhexyl)phthalate.svg
File:Laying sewer hi res (2).jpg
Laying sewer hi res (2).jpg
File:Builder's tudorbethan.jpg
Builder's tudorbethan.jpg
File:Double glazed Units.JPG
Double glazed Units.JPG
File:Men's black PVC pants 01.jpg
Men's black PVC pants 01.jpg
File:12in-Vinyl-LP-Record-Angle.jpg
12in-Vinyl-LP-Record-Angle.jpg
File:Vinyl Einmalhandschuhe.JPG
Vinyl Einmalhandschuhe.JPG
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