Long term storage of biodiesel/petrol diesel blends in polyethylene fuel tanks

This paper explores the long-term effects that an ageing biodiesel fuel blended with low sulfur diesel fuel at concentrations of 0%, 15%, 50%, 85%, and 100% (v/v) can have on polyethylene materials. Rotationally molded fuel tanks made of linear low density polyethylene or crosslinked polyethylene were used to appropriately mimic the storage environment of fuels, though the study also considered immersed polymer specimens as this test approach is more commonly reported on in the literature. The extent of oxidation for the fuels was monitored by determination of its peroxide value and acid number over time, with both values being consistently higher for blends with higher biodiesel content. Storage at 80 °C for up to 56 days resulted in significant oxidation of the fuel while testing up to 380 days at 23 °C produced no change in peroxide or acid concentration. The change in mechanical properties for the polyethylenes due to fuel was determined by tensile testing. Comparing the tensile data to the oxidation species in the stored fuels revealed that noted mechanical losses did not correspond with higher concentration of hydroperoxides or acid species but rather occurred as a result of fuel absorption. No difference was found in this regards between the two polyethylene species.