Internal and External Lubricants are two types of lubricants used in PVC applications. They serve the process of reducing friction. However, both of these category of lubricants act differently and have distinct functions. There are certain lubricants such as Stearic Acid that act as both external and internal lubricants.

Oleochemical derivatives, Ester, and N- Butyl stearate are examples of internal lubricants used for PVC processing.

Unlike internal lubricants that enhance the polymer melt’s flow properties, external lubricants tend to migrate to the PVC’s surface, forming a lubricating layer between the melt and the processing equipment.

Internal Lubricants improve the flow characteristics of the PVC melt during processing and External Lubricants reduce the friction between the PVC melt and the metal surfaces of the processing equipment.