ABSTRACT
The service life of rubber hoses exposed to jet fuel has been determined using accelerated immersion aging. The inner tube rubber has been identified as chlorinated poly(ethylene) or CPE. Immersion aging in jet fuel (JP8 +100) took place from 50° to 125°C in increments of 15°C, for various exposure times. Aged samples were tested for mechanical properties, volume swell resistance and network chain density by solvent swell in order to assess the level of rubber deterioration. Time-Temperature Superposition (T-TS) was applied to the testing results using 95°C as a reference temperature. Hose samples initially softened then progressively stiffened leading to a loss in ultimate properties (both tensile strength and elongation at break). Volume swell slowly increased during aging but remained under 80%. The network chain density slowly increased before declining under severer conditions. Diffusion-Limited Oxidation (DLO) was operating and influenced test results collected above 95°C. A linear Arrhenius behavior however, was observed using elongation at break as the material response and an activation energy of 50 ± 10 kJ/mol for the overall degradation process was calculated. Possible service lives in the 6 to 10 year range have been put forth including the predicted ultimate properties and volume swell changes. An 8 year service life corresponds to a loss of 80% and 40% respectively of the tensile strength and elongational properties of the rubber. Volume swell is expected to reach 65%. This is a reasonable upper limit for the rubber property losses and is in line with the expectations of a CPE rubber used in a fuel environment.
