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Which elastomer seal materials are suitable for use in biofuels?
Abstract
There is increasing interest in the use of hydrocarbon fuels derived from renewable resources. This is being driven by a variety of environmental, political and economic concerns and attracting considerable industrial investment for the production of renewable supplies to replace both gasoline and diesel fuel. The introduction of these fuel sources, as a blend with traditional mineral fuel supplies is placing additional demands on the compatibility of the elastomer materials used for seals. This feature reviews information on suitable materials from DuPont for use in butanol and Freudenberg Simrit for biodiesel.
... In this sense, there is increasing interest in the use of hydrocarbon fuels derived from renewable resources. This is being driven by the variety of environmental, political and economic concerns and attracting considerable industrial investment for the production of renewable supplies to replace both gasoline and diesel fuel (Flitney, 2007). ...
... The first results clearly show the necessity of a better evaluation of the polymeric components of these engines with a degradation potential in using biodiesel. Flitney (2007) was the first researcher to report the performance of fluoroelastomers with various fluorine contents in butan-1-ol and biodiesel fuel mixtures. In another study, Trakarnpuk and Portangjitlikit (2008) investigated the effect of a biodiesel 10%/diesel fuel 90% mixture on the properties of some elastomers that are commonly used in automotive applications. ...
An engine industry from Caxias do Sul city (RS, Brazil) has developed tests with biofuels to adapt their products to new fuel trends. Thus, this study aims to examine the components of their engines with potential degradation in the biodiesel usage. The most important aspects that were studied include fuel hoses, sealing rings and painting degradation. This work evaluated polymeric materials in terms of the direct contact with biodiesel from soybean in different proposed compositions with diesel and compared the currently used materials with other elastomers that were proposed by the manufacturers of these components to choose the best performance for this application. The paint performance was also verified to evaluate the resistance aspects to fuels and to compare them to the proposed improvements to these engines. The results indicate that it is possible to use the proposed fuel hoses and sealing rings for some applications in specific biodiesel ratios. Additionally, the blistering and adhesion tests appear to be satisfactory for some of the studied systems.
... Another issue is that biodiesel is electrically more conductive than gasoline and petrodiesel fuel and thus it may induce galvanic metal corrosion mechanism in steels [7]. Regarding the compatibility with polymers, most of the work has been published reporting on the swelling phenomenon and degradation in the mechanical properties of elastomeric parts as sealants [8,9]. Swelling is related to an increase in volume of the material due to its interaction with a solvent material that is not able to solubilize it, being the solvent retained into the material. ...
... Visual inspection (not presented here) revealed a yellowish appearance of HDPE samples after being immersed in all fuels, compared to the white color of the pristine samples. Both information, weight gain and discoloration, suggest a fluid absorption phenomenon, which can be interpreted as swelling occurrence, that is commonly reported for polymers, especially elastomers [8,9]. It is worth noting that the swelling occurs during the first 75 days of immersion and remains stable, with no further fluid absorption. ...
Compatibility of the new environmentally-friendly alternative of diesel engine fuels, biodiesel, with storage and engine part materials, is still an open issue. In this work, the interaction between three fuels (petroleum diesel and two types of biodiesel — soybean and sunflower) and two materials (carbon steel and high density polyethylene) used in storage and automotive tanks, is analyzed in detail. A wide set of characterization techniques was used to evaluate the changes in both solid and fluid materials, as weight change measurement, optical, scanning electron and atomic force (AFM) microscopies, Raman and FTIR spectroscopies, and differential scanning calorimetry. The AFM technique allowed detecting surface roughness and morphology changes in the metallic material following the trends in the weight losses. In the case of polymeric material, weight gain by fluid absorption occurred, being detected by the spectroscopic techniques. The biodiesel fuels underwent some ageing however this phenomenon did not affect the interaction between the biodiesel fuels and the substrates. The petrodiesel, which did not age, caused more significant degradation of the substrates.
... However, the ability of biodiesel to be oxidative in nature leads to corrosion and degradation of various materials [4][5][6]. As a consequence, the investigation of the effect of biodiesel on different materials in engine components is a wavering apprehension [5][6][7][8][9][10][11]. COME (Cotton Seed Oil Methyl ester) biodiesel derived from cotton seeds provides a better efficiency compared to commercial diesel and produces a much cleaner environment [12]. ...
Biodiesel has emerged as one of the major sources of renewable energy in automotive applications substituting the convention diesel. However, the compatibility of biodiesel and rubber components remains a major concern. Indeed, it is found that biodiesel tends to swell rubber components resulting to their faster degradation. Thus, studies focusing on the compatibility of newly developed biodiesel are essential for rubber durability. Along this line, the main purpose of the present study is to investigate the swelling characteristics of rubber in cottonseed oil biodiesel. Two types of unfilled and filled rubbers are considered: natural rubber (NR) and polychloroprene rubber (CR). For filled rubbers, two carbon black contents are used: 25 and 40 phr. The rubber samples are immersed in conventional diesel fuel, biodiesel and diesel-biodiesel blends for 1000 hours at room temperature (25 °C). The evolutions of rubber mechanical properties such as hardness, tensile modulus and tensile strength are investigated as well as the macroscopic stress-strain characteristics. For both rubbers, it is found that the decrease in the mechanical properties becomes more significant as the biodiesel content increases. Finally, a continuum model predicting equilibrium swelling proposed by Ch’ng [S.Y. Ch’ng. Coupling between diffusion of biodiesel and large deformation in elastomers: from experimental investigation to constitutive modeling. Ph.D. Thesis. University of Malaya, Malaysia. 2014] is adopted to simulate the effect of carbon black on the stress-free equilibrium swelling of rubber.
... In general, static and dynamic seals made up of elastomeric materials are the most prone to fail due to swelling and changes in their mechanical properties, which may result in dangerous leakages. Some of the most common materials employed in gaskets, orings and dynamic seals for automotive fuel systems are rubber, ethylene-propylene-diene monomer (EPDM), nitrile-butadiene rubber (NBR), neoprene (poly-chloroprene or chloroprene rubber, CR), fluorelastomers (FKM), silicone rubber (vinyl-methyl silicone, VMQ), PTFE, etc. [23,24], being FKM the most suitable for seals used in diesel and biofuels systems [25]. However, elastomers have different physical and chemical properties, so they are suggested for use only in certain environments where degradation is minimal. ...
Straight vegetable oils (SVO's) are currently used as renewable sources of fuel in diesel engines for electricity production, transport or agricultural mechanization. Despite various environmental benefits, the use of SVO's may result in shortcomings for the engine operation, in particular, degradation of seals and polymeric components. Thus, deterioration of seals into contact with SVO's in engines must be analyzed to make a safe use of these alternative fuels. In this work, the deterioration of silicone rubber (VMQ), fluoroelastomer/Viton® (FKM), ethylene-propylene-diene monomer (EPDM) and neoprene/chloroprene rubber (CR), upon exposure to straight Jatropha oil (SJO), diesel, and a blend 80% diesel-20% SJO (B20), respectively, was analyzed by immersion tests with measurements of changes in mass, volume, tensile and tear strengths, and hardness. Complementary measurements of changes in viscoelasticity, surface morphology, topography, and chemical composition provided further insight into the understanding of deterioration of the elastomers. Overall, the four elastomers exhibited negligible deterioration with SJO while only FKM exhibited minimal deterioration with diesel and B20. VMQ and FKM were the less deteriorated elastomers by SJO and diesel, respectively. These experimental results were found to be in good agreement with predictions of compatibility based on the use of the Hansen solubility theory.
... Acrylic rubber [125] Chloroprene [101] Ethylene-propylene-diene monomer [98,100,101,[156][157][158] Fluoroelastomer [69,70,97,98,100,122,125,[158][159][160][161] Fluorosilicone [122,160,162] Hydrogenated nitrile rubber [70,125,158,160] Nitrile rubber [70, 97, 98, 100-101, 120, 125, 158, 160, 161, 163-171] Nylon [172] Polyamide [158] Polychloroprene [97] Polyethylene [173] Poly-tetrafluoroethylene [101,174] Synthetic rubber [98] Silicone rubber [98,101] ...
Compatibility of fuel delivery materials (FDM) with biodiesel fuel in the fuel delivery system (FDS) under real-life common rail diesel engine (CRDE) operation poses a challenge to researchers and engine manufacturers alike. Although standard methods such as ASTM G31 and ASTM D471 for metals and elastomers, respectively, are deemed suitable for evaluating the effects of water content, total acid number (TAN) and oxidation products in biodiesel on FDM degradation, they do not resemble the actual engine operation conditions such as varying fuel pressure/temperature as well as the presence of a wide range of materials in the FDS of a diesel engine. Hence, the current allowable maximum 20 vol% of biodiesel with 80 vol% of diesel (B20) for use in diesel engines to date is debatable. Additionally, biodiesel utilization beyond B20 is essential to combat declining air quality and to reduce the dependence on fuel imports. This thesis aims to elucidate the actual compatibility present between FDM and biodiesel in the FDS under real-life CRDE operation. This was achieved through multi-faceted experimentations which commenced with analyses on the deteriorated palm biodiesel samples collected during and after CRDE operation. Next, the fuel properties which should be emphasized based on the deteriorated fuel were determined. This was then followed by ascertaining the effects of the emphasized fuel properties towards FDM degradation. Ultimately, the actual compatibility of FDM with biodiesel under engine operation through modified immersion investigations was determined. FDM degradation acceleration factors such as oxidized biodiesel, TAN and water content were eliminated since these factors were not affected based on the analysed fuel samples collected after engine operation. No oxidation products such as aldehydes, ketones and carboxylic acids were detected while the TAN and water content were within 0.446% and 0.625% of their initial values, respectively. Instead, the biodiesel’s dissolved oxygen (DO) concentration and conductivity value were not only found to have changed during and after engine operation by -93% and 293%, respectively, but were also found to have influenced biodiesel deterioration under engine operation. These two properties were subsequently discovered to have adversely affected FDM degradation independently. The copper corrosion rate and nitrile rubber (NBR) volume change increased by 9% and 13%, respectively, due to 22% increase in the conductivity value. In contrast, the copper corrosion rate and NBR volume swelling reduced by 91% and 27%, respectively, due to 96% reduction in the DO concentration. Ultimately, copper corrosion and NBR degradation were determined to be lowered by up to 92% and 73%, respectively, under modified immersion as compared to typical immersion condition. These outcomes distinctly show that acceptable to good compatibility is present between FDM and biodiesel under CRDE operation. The good compatibility is strongly supported since only a maximum lifespan reduction of 1.5 years is predicted for metal exposed to biodiesel as compared to diesel for a typical component lifespan of 15 years. For the elastomers, acceptable compatibility is found present between elastomer and biodiesel based on the determined 11% volume change which conforms to the tolerance level of elastomer degradation as stated by the elastomer manufacturers. These are especially true for the evaluated metals and elastomers investigated under the modified laboratory immersion which replicates similar conditions to a real-life CRDE. Overall, this work has contributed to the advancement of knowledge and application of biodiesel use in diesel engines.
... However, since unsaturated molecules as methyl linoleate (C18:2), methyl linoleate (C18:3) are very susceptible to degradation [8] and oxidation [9], biodiesel is more oxidative leading to corrosion and degradation of different materials [10][11][12]. Therefore, the study of the biodiesel effect on several different brands of materials used in engines is a growing concern [11][12][13][14][15][16][17]. ...
... However, biodiesel is more oxidative than petrodiesel due to the presence of unsaturated fatty acids [8] which enhance corrosion and material degradation [9][10][11]. Due to this behavior, the compatibility of biodiesel with elastomers is a growing concern as these materials are widely employed in the fuel system and in many engine parts [10][11][12][13][14][15][16]. When swollen by fuel rubber may contain liquid like components (fuel and dissolved components in pores), gel-like component (swollen rubber matrix) and solidcomponent (intact rubber). ...
Biodiesel has been incorporated into the energy matrix in several countries, but its compatibility with some materials used in automotive engines is of growing concern. In the present study, comprehensive multiphase (CMP) NMR is applied to understand the different phases in fuel-rubber systems. CMP NMR is a novel technology that integrates all the hardware from solution-, gel- and solid-state into a single NMR probe, permitting all phases to be studied in samples in their natural unaltered state. Transverse relaxation experiments in combination with inverse diffusion editing permit the increasing mobility of the rubbers chains with biodiesel exposure to be monitored. Conversely diffusion editing and RADE experiments highlight the more rigid domains. In summary NR and NBR showed the absence of highly rigid domains after exposure to biodiesel whereas SBR and EPDM especially better retained their structural integrity. 13C editing protocols and 13C-1H HSQC confirmed the increasing gel-like properties of NR, NBR and SBR with exposure to biodiesel. However, variable contact time experiments showed that biodiesel penetrates even the most resilient EPDM pores causing relaxation of the polymer chains and demonstrates that NMR is sensitive enough to highlight even the very slight swelling of the EPDM. Through these results it is possible to observe that the elastomer that exhibits the lowest susceptibility to biodiesel in molecular terms was EPDM, followed by SBR, NR, and NBR. It was also observed that biodiesel molecules were present in the EPDM structure despite the literature reporting its general resilience to biodiesel.
... It has been observed that polyethylene (PE) displays a poor compatibility with biodiesel fuels. Most of the literature deals with elastomeric sealants swelling when exposed to miscible liquids, especially hydrocarbons [3,4]. It has been shown that the degree of swelling is a decreasing function of the crosslink density and of the polymer-fuel interaction parameter, this latter being an increasing function of the difference between polymer and fuel solubility parameters. ...
This work deals with a study of stabilizers loss by extraction in ethanol–cyclohexane mixtures simulating ethanol based biofuels. As theoretically predicted, cyclohexane has an extractive power considerably stronger than ethanol one and its effect predominates, even in fuels containing only 10% cyclohexane. Antioxidant depletion displays first-order kinetics indicating that loss kinetics are extraction rather than diffusion controlled.
Diesel engines are robust and reliable besides their good fuel economy. However, these engines produce higher exhaust emissions with fossil diesel and further these emissions level increases when operated on biodiesels. A common rail direct injection (CRDi) engine shows higher brake thermal efficiency (BTE) and lower emissions as compared to compression ignition mode (CI mode) of engine operation. This research paper revealed the results of diesel engine operated in CRDi mode with single injection (SI) and multi-injections (MI) of fuel using diesel and biodiesel of honne oil at 80% load. The CRDi engine operation with both SI and MI showed higher BTE and lower emissions as compared to CI mode. The peak pressure and heat release rate of a CRDi engine operation were lower as compared to CI mode. Overall, it could be concluded that biodiesel-powered CRDi engine with double injection and triple injection could reduce oxides of nitrogen (NOx) emissions by 40.8% and 50%, respectively, while smoke emission by 10% and 16.6%, respectively. However, there was a little penalty on BTE and brake-specific fuel consumption.
This paper explores the compatibility of biodiesel with different grades of polyethylene, specifically examining the extent of plasticization in order to gain a better understanding of the biofuel's compatibility with this common polymer. Its bulk influences on polyethylene were investigated by gravimetric and mechanical testing, and by the application of a newly developed nondestructive ultrasonic testing method. Diffusion rates and the extent of plasticization by biodiesel were compared to results obtained with toluene, a known plasticizer for polyethylene. Mechanical and gravimetric analysis showed that biodiesel exhibited bulk attributes of a plasticizer for the tested polyethylenes with reduced moduli proportional to the amount of fuel uptake and that uptake was inversely proportional to crystalline content of the polymer. Based on uptake amounts, the efficiency of biodiesel as a plasticizer towards polyethylene was found to be more than double that of toluene. However, spectral analysis by ultrasonics showed that absorbed toluene and biodiesel influenced the microstructure of polyethylene differently. Notable differences in internal stresses were noted between the two fluids for the same amount absorbed. A subsequent study analyzed the impact that biodiesel degradation had on plasticization. Although the trend showed a slight change in diffusion rate with increasing oxidation of the medium, the mechanical and ultrasonic results did not show significant differences between fresh and degraded biodiesel within the 45 days span of the test. Combining the evidence observed in this study, a mechanism is proposed for biodiesel plasticization that can help with failure prevention and material selection.
Diesel diffuses into neoprene matrices 10% faster than palm ethyl biodiesel at 20°C. In contrast, the palm biodiesel soaks highly plasticized PVC five times faster than diesel. Phthalate plasticizer leaks from the PVC matrix 14 times faster when biodiesel is the absorbed liquid, relative to petrodiesel. This biodiesel penetrates polybutadiene-styrene resins at rates that depend on the ratio of phenyl to CHCH units in the resins. Copyright © 2008 John Wiley & Sons, Ltd.
Eighteen features during the year have covered a variety of rotary seal types, plus reciprocating and static seals together with materials. Examples of the latest analysis techniques for elastomer and mechanical seals have been covered in some depth while others have discussed interesting applications and imaginative marketing approaches.
The goal of this study is to find an industrial alternative application to hard chromium plating. The first part presents the appropriate environmental and chemical behaviour of NiCrBSi alloy and AISI 316L stainless steel coated by thermal spraying and laser cladding. This paper will concern the wear resistance of these dry coatings. However, stainless steel has awful performance in friction contacts, and this material cannot be suggested as a substitute solution to hard chromium coating for applications where the wear resistance is an important issue. Therefore the tribological pin-on-disc tests will only concern the NiCrBSi coatings. Consequently in the second part, tribological characterizations were carried out in order to determine the alternative potential of NiCrBSi coatings compared to electrolytic hard chromium plating, in applications to resist wear. The coatings are sprayed by Atmospheric Plasma Spraying (APS) and laser cladding (with a diode laser). Especially, the dry coated samples present a good tribological behaviour, whereas the wear mechanisms are different between APS and laser cladding coated samples. Laser cladding allows the manufacture of denser coatings, thus the mechanical properties are increased while the wear rate was reduced. At the same time, APS coated samples show a lower value of shear strength in comparison with laser cladding. That is the reason why fatigue is the main wear mechanism, and this process is called splat delamination.
Performance of Viton fluoroelastomers in butanol-fuel blends’ DuPont Performance Elastomers
- Eric Thomas