PVC has a variable melting point

The melting point of polyvinyl chloride (PVC) varies and in most cases can not be precisely determined to an exact temperature. Pure PVC begins to decompose below the actual melting temperature. To delay this time and increase the melting point, plasticizers and stabilizers are added.

Melting range and decomposition

The PVC, which is used as a floor covering, consists of mixtures whose melting point is between 160 and 180 degrees Celsius. The material decomposition starts ready from about 120 degrees. This melting temperature is sufficient so that the PVC coating can withstand, for example, spilled boiling water in the kitchen.

To form PVC, it is heated to temperatures between 120 and 150 degrees. In this area, the PVC can be redesigned and keeps the shape when cooling down. When welding PVC, temperatures between 250 and 280 degrees are used. The ignition temperature of PVC is about 380 degrees.

Temperature steps during production

The production of PVC involves several temperature steps, each of which produces a specific material reaction:

  • 40 degrees: The mixture of PVC and plasticizers swells together and the plasticizer combines with the granular PVC components.
  • 60 degrees: The PVC begins to thicken and gain strength
  • 100 to 120 degrees: All ingredients are almost uniformly mixed and the PVC develops increasing viscosity without becoming liquid.
  • 160 to 180 degrees: All ingredients form the stable homogeneous mass from which, after cooling, the usable floor covering is created.

Decomposition temperature of PVC

Almost more important than the melting point of PVC is the temperature at which the melting or molten plastic releases harmful vapors. From about 200 degrees Celsius, the ingredients decompose increasingly intense. The onset of decomposition is indicated by a discoloration of the cut edges, which assume a yellow-brown color. PVC is a chlorinated plastic and when it evaporates, hydrochloric acid vapors, dioxins or other softening substances such as formaldehyde escape.

Tips & Tricks

If you heat PVC to work it, always wear respiratory protection and provide adequate ventilation. In closed rooms, professional air extraction is required.

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