• About Vinyl
• Associations
• Science
• Environment
• Companies
  

PVC is a thermoplastic. This means that it softens as it is heated, and hardens as it cools.
It was first made in 1872. To start with it was nothing more than a laboratory curiosity because no one really knew what to do with it. In fact, the first PVC wasn't very good. When heated or exposed to sunlight, the molecules broke up and an acidic gas was given off.

Decades later, scientists discovered that chemicals could be added which would make it stable and resistant to light and heat. This meant good-quality PVC products could be manufactured.

PVC was first used instead of rubber to insulate the wires in electrical cables. This was about 60 years ago, during Word War II, when rubber was in short supply. Since then it has replaced rubber for insulation and found many other applications. These days, it's the second most popular plastic in the world.

PVC can be supplied to factories either as a powder or, when additives are included, in pellet or granular form. This raw PVC is then heated and shaped into a final product using a number of different techniques.

When softened by heating, the PVC powder or pellets can be moulded or extruded to achieve the desired shape.

PVC can be fashioned into just about any shape or form. It can be made into pipe, sheet, wire or tape. It can also be used as a coating for other materials, like paper, cardboard or metal.

Extrusion:

hot, soft plastic is squeezed through a hole of the correct dimensions. It hardens as it cools. Used for making continuous lengths like plastic sheets or pipes.

Injection moulding:

hot plastic is forced into a mould of the desired shape. The mould is then cooled and opened up to remove the solid plastic object. Used to make more complicated shapes like pipe fittings.

Blow moulding:

air is blown through a tube of hot plastic, pushing the PVC outwards to the sides of the mould. Good for making hollow objects such as bottles.

Calendering:

Squashing PVC between heated rollers to make thin sheets.

PVC can be made with excellent transparency or it can be changed to almost any colour.
It can be blended with certain additives to give it special properties like scratch resistance, flexibility and sunlight resistance. Many different mixtures of PVC can be made depending on the final purpose.

For more information on the additives used in PVC, go to the section on Health and Environment.

Step 2 Producing Vinyl Chloride Monomer

The ethylene dichloride is then decomposed by heating in a high temperature furnace, according to the reaction:

The hydrogen chloride is reacted with more ethylene in the presence of oxygen (a reaction known as oxychlorination) to produce further ethylene dichloride. The ethylene dichloride so produced is decomposed according to the above equation, and the hydrogen chloride again returned for oxy chlorination.

The overall reaction can be shown by adding together the above equations to give:

Step 3 Manufacturing Polyvinyl Chloride

PVC is made by a process called addition polymerization. This reaction opens the double bonds in the vinyl chloride monomer (VCM) allowing neighboring molecules to join together creating long chain molecules.