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The aging and “sour” gasoline resistance of fuel line hose tube can be improved by appropriate choice of compound to meet the requirements of recently upgraded specifications. The use of an NBR designed for heat resistant compounding, together with silica filler and selected plasticizer and antioxidant and a low sulphur sulphur-donor cure all contribute to improved performance. It is preferable to use cadmium oxide as activator but promising zinc oxide activated compounds have also been identified. It is desirable for both aging and “sour” gasoline resistance to use an NBR with acrylonitrile content as close to 40% as low temperature requirements permit.

The effects of nonpolymer constituents and antioxidants on the aging behavior of nitrile rubber polymers are discussed. The paper covers experimental work carried out to develop a range of rubbers which are responsive to heat resistant curing systems, the optimization of these systems in terms of antioxidant protection, and the practical use of this type of nitrile rubber in compounding to meet critical specifications. The authors conclude that nitrile rubber polymers produced according to the SP principle offer excellent heat resistance in a variety of curing systems. Furthermore, such polymers have an advantage over nitrile polymers produced with stabilizers which function as efficient antioxidants, since this latter type of polymer can detract from aging resistance, depending on the curing system used.