ABSTRACT
The objective of this research was to determine the resistance of frequently used sealing materials such as EPDM, FKM, FVMQ, CR, CSM, IIR, NBR, PA, PUR and VMQ in aged biodiesel and heating oil B10 with 10 % biodiesel.
The mass, tensile strength, breaking elongation and Shore hardnesses of the test specimens were determined before and after exposure in non-aged, one-year, two-year, three-year and four-year aged biodiesel and B10 at 20 °C, 40 °C and 70 °C.
A threshold for the reduction in tensile properties and Shore hardness is not set in the international standards. Therefore, a threshold of 15 % was set for the evaluation of the compatibility. The decrease in tensile properties and Shore hardness increased with the age and the temperature of the biodiesel and the heating oil.
The age of the biodiesel was not relevant for the sealing materials CR, CSM, EPDM, IIR and NBR, which were generally not resistant to biodiesel and B10. FKM and PA showed high compatibility in non- aged and aged biodiesel. FVMQ and PA could be evaluated as resistant in non-aged and aged B10 at 20°C and 40°C, whereas FKM was resistant up to 70°C despite of the age of B10.
INTRODUCTION
Biofuels are viewed as a major source of energy. There are two principal types of biofuels currently being used. These are ethanol instead of gasoline and biodiesel instead of diesel.1 Ethanol is produced from carbohydrates such as sugar cane, sugar beet, and corn. Biodiesel is manufactured from oilseeds, predominantly rapeseed, oil palm, and soy. Differences between diesel and biodiesel are due to their different chemical natures. Diesel is composed of hundreds of compounds which boil at different temperatures, while biodiesel contains only a few compounds, primarily the C16-C18 carbon chain, depending on the vegetable oil. 2, 3
Biodiesel is subject to degradation processes like oil and grease. The oxidative degradation products of vegetable oil esters in biodiesel particularly lead to enhanced sedimentation in blended fuels. Munach et al. examined spectroscopically the interaction between diesel fuel and biodiesel in blended fuels. It was shown that sedimentation occurs in addition to the oxidative ageing of different mixtures of diesel fuel and biodiesel.4