Plasticizers

 
In EPDM, processing oils are used to adjust the hardness and modulus of the vulcanizate and to improve the flow behavior and extrusion properties. Normally paraffinic mineral oils and also, if necessary, naphthenic mineral oils are used to plasticize EPDM compounds.

Phosphoric acid esters and chlorinated hydrocarbons are occasionally incorporated to improve the flame resistance. LANXESS offers several grades which are already oil extended including grades which are using white oil for colored applications.

For optimum heat resistance, process oils with relatively high paraffinic contents are used. Other additives, such as paraffin waxes of low molecular weight, polyethylene and polybutene, can also be used as process aids. As with fillers, the EPDM grades of higher molecular weight tolerate higher plasticizer loadings. This is particularly important in the formulation of compounds of low hardness where a high compound viscosity is required to prevent porosity. High viscosity oils are preferable here.

With the same molecular weight, polymers of higher ethylene content permit the use of higher filler loadings than do those of lower ethylene content.

 

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