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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.
Materials compatibility is a major concern whenever the fuel composition is changed. The question arises of whether sealing materials are resistant to fuels with bioethanol and biodiesel (rapeseed oil fatty acid methyl ester).
Previous research considered the resistance of frequently used sealing materials such as FKM (fluorocarbon rubber), FVMQ (methyl-fluoro-silicone rubber), VMQ (methyl-vinyl-silicone rubber), EPDM (ethylene-propylene-diene rubber), CR (chloroprene rubber), CSM (chlorosulfonated polyethylene), IIR (butyl rubber), PA (polyamides), NBR (acrylonitrile-butadiene rubber) and PUR (polyester urethane rubber) in fuels and heating oil with admixtures of biogenic substances such as biodiesel and B10 (heating oil with 10 % biodiesel) under purely static conditions.
The aim of this study was to evaluate the fluorocarbon rubber performance under compressed conditions. For the investigations, the mass and the compression set of the FKM test specimens were determined before and after exposure for 3, 7, 14, 28, 56 and 90 days in E10 (fuel with 10 % ethanol), E85 (fuel with 85 % ethanol), biodiesel (fatty acid methyl ester, FAME), Super (fuel with max. 5 % ethanol), diesel fuel with max. 5 % biodiesel, pure diesel fuel, Super Plus (fuel without ethanol) and heating oil with 10 % biodiesel (B10) at 40 °C according to ISO 815-1 “Rubber, vulcanized or thermoplastic - determination of compression set – Part 1: At ambient or elevated temperatures”. The compression set test belongs beside the determination of the Shore hardness, the density and the tensile properties to the basic test methods for elastomers. It was measured in regular time intervals up to a re-drying of more than 90 days after relaxation of test specimens. For comparison, FKM test specimens were exposed without fuel under compressed conditions at 40 °C.
The highest mass increase of FKM test specimens was measured after 90 days exposure in E10 by 9 %, followed by 8 % in Super fuel, by 4 % in E85 and by 0.6 % in biodiesel. Mass increase and swelling of the test specimens in E10 and Super fuel with max. 5 % ethanol had an influence on the compression set values which were subject to high fluctuations in comparison to the values obtained after exposure to other fuels such as biodiesel, diesel fuel and B10.
The results of the present work confirmed the higher swelling of the elastomers such as FKM in E10 obtained under static condition. It can be concluded on the basis of the mass increase and compression set values that FKM is resistant in all fuels under compressed conditions at 40 °C.
Biodiesel is viewed as a major source of energy. In areas such as the European Union, where 80 % of the oil-based fuel is imported, there is also the desire to reduce dependence on external oil supplies.
Materials compatibility is a major concern whenever the fuel composition is changed. The question arises of whether polymeric materials are resistant to heating oil with 20 % biodiesel (B20) in comparison to pure heating oil.
The polarity of biodiesel increases its solvency and facilitates permeation and extraction. Solvation, swelling and/or extraction lead to changes in the physical properties. Extraction alters the fuel chemistry. These chemical changes could also accelerate the degradation (hydrolysis and oxidation) of the polymeric material with the loss of additives and stabilizers.
The objective of this research was to determine the resistance of frequently used materials for components in middle distillate facilities such as ACM, FKM, HNBR, PA, PE, POM, PUR and PVC in heating oil and heating oil blend B20 for 84 days at 40 °C, and FKM, HNBR, PA, POM, PUR and PVC at 70 °C.
Mass, tensile strength, breaking elongation and Shore hardness A (D) of the test specimens were determined before and after exposure for 84 (42) days in the test fuels under static conditions.
For the investigations under compressed conditions, the mass and the compression set of FKM test specimens were determined before and after exposure for 3, 7, 14, 28, 56 and 90 days in B20 at 40 °C and 70 °C according to ISO 815-1 “Rubber, vul-canized or thermoplastic - determination of compression set – Part 1: At ambient or elevated temperatures”.
There is not determined a threshold for the reduction in tensile properties and Shore hardness in the international standards. Therefore, a threshold of 15 % was determined for the evaluation of the compatibility.
The change of tensile strength and breaking elongation of test specimens made of ACM, FKM, HNBR, PA, PE, POM, PUR and PVC exposed to heating oil and the blend B20 was less than 15 % at 40 °C. A maximum reduction in Shore hardness A of 14 % was determined for ACM at 40 °C and for HNBR of 15 % at 70 °C.
It can be concluded that ACM, FKM, HNBR, PA, PE, POM, PVC and PUR were resistant in B20 at 40°C. FKM, PA, POM and PVC were evaluated as resistant in heat-ing oil and B20 at 70 °C, HNBR and PUR were not resistant in these fuels at 70°C.
Based on the mass increase and compression set values of FKM test specimens it can be stated that FKM is resistant in B20 under compressed conditions at 40 °C and 70 °C.