Chemical Exposure Testing of Rubber - fluid compatibility and chemical ageing

Chemical Exposure Testing of Rubber

Exposure of rubber materials or components to a chemical environment may result in physical (swelling) and chemical changes. These changes can in turn affect the mechanical properties and the functional performance of a component.

Fluid compatibility can be assessed by measurement of:

Permeation, diffusion and solubility of gases and liquids solubility parameter

Compatibility between rubber and fluid

Chemical ageing can be assessed by monitoring property changes during exposure.

Ageing in an inert atmosphere e.g. Nitrogen (continuation of cure chemistry)

Air ageing (oxidative effects)

Hostile fluids (hydrogen sulphide, amines, amides, methanol, de-icing fluids, anti-freeze, oils, additives etc)

Property changes can be monitored with time and the accelerating effect of raising the temperature can be quantified following an Arrhenius approach (provided no transition or degradation temperature is surpassed). From this, longer-term lower temperature performance can be predicted, provided chemical and physical effects can be separated.

Careful measurement of creep during fluid exposure can differentiate between physical and chemical effects, as shown in the graph above.