Release Agents, Lubricants, Stabilizers, and Antistatics

Release agents are intended to prevent plastics from adhering to molds. Silicones are normally used for this purpose in the rubber industry. 

Lubricants lower the coefficient of friction between polymer and machine parts, so that lower pressures can be used during processing. Stearic acid and zinc stearate are typical lubricants. With emulsion polymerizations, the emulsifier residues remaining in the polymer can act as a lubricant. Lubricants are added in amounts of 1-5 %. Only a small amount of added lubricant really works by lubrication, however, since the greater part of the additive resides in the interior of the plastic. Lubricants often produce translucent or opaque films. 

Stabilizers are intended to prevent degradation reactions (in the broadest sense) of plastics during processing (heat stabilizers against thermal decomposition) and in practical use (antioxidants and UV absorbers to protect against light and aging). They are added in amounts of 1 %. See Chapter 24 for their protection mechanisms. 

Antistatics prevent electrostatic charges from forming on plastic surfaces. Electrostatic charging of the surface leads to such problems as easier 

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