The Development of Oil-resistant Rubbers with Low Brittle Point

THE DEVELOPMENT OF OIL-RESISTANT RUBBERS WITH LOW BRITTLE POINT 

If one considers the polymers of methyl, ethyl and n-butyl acrylate it will be clear that the increase in the length of the side group will have two important effects, namely the Tg will be depressed and the oil resistance will be reduced. Thus the T, of poly(methyl acrylate) is -t-8°C, that of the ethyl poymer -24 C and that of poly(n-butyl acrylate) as low as -54 C. Whilst the low Tg of the butyl polymer (and the related brittle temperature) is highly desirable in a rubber for automotive and other uses liable to be required to operate at low temperatures, poly(n-butyl acrylate) seriously lacks in oil resistance. 

For this reason early developments centred round two approaches  

The development of rubbers based on ethyl acrylate together with some cure-site monomer  

The development of copolymers of n-butyl acrylate with monomers conferring oil resistance, such as acrylonitrile. 

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