Degradation of aviation sealing materials in rapeseed biodiesel

Nowadays, the airline industry and worldwide companies in the aerospace industry have been forced to find new ecological alternatives to traditional fuels to substitute as aviation fuels and kerosene. In aero turbo engines, rubber seals based on nitrile–butadiene rubber (NBR) with different contents of acrylonitrile are the most commonly used for the production of seals. This NBR is characterized by excellent physical and mechanical properties. In this article, we present the effects of critical operating conditions and the addition of the methyl ester of rapeseed oil to aviation fuel in relation to seals for aircraft engines. In this study, we evaluated changes in the physical and mechanical properties of rubber blends that were produced from NBR rubber. The exact composition and material properties were obtained from the producer. Static immersion tests in B10 (10% biodiesel in diesel), B50 (50% biodiesel in diesel), B75 (75% biodiesel in diesel), and B100 (100% biodiesel) were carried out at a higher temperature (100°C) for 500 h and at laboratory temperature (23 ± 2°C) for 3000 h. At the end of the immersion test, the degradation behavior was investigated by the measurement of the relative changes in the weight, hardness, tensile strength, and elongation. The change in the rubber surface morphology was studied by optimal microscopy and with a digital camera. The results show that the extent of rubber blend degradation was observed for samples that were exposed to a higher concentration of biodiesel and to a higher temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42254.     

Studying the efficiency of the diesel fuel isodewaxing process on a zeolite-containing nickel–molybdenum catalyst

A GIP-14 diesel fuel isodewaxing catalyst based on a mixture of zeolites with different pore structures and entrance sizes and transition metals Ni and Mo as hydrogenating components is developed. Its stability during operation is studied. It is shown that the cold filter plugging point (CFPP) of the diesel fuel reaches values below–38°C at its yield of 92–93 wt %, temperatures of 305–310°C, and a feedstock hourly space velocity (FHSV) of 3 h^?1. A pilot diesel fuel sample is tested according to GOST (Russian State Standard) R 55475–2013. Comparative tests of domestic and foreign catalysts show that the developed GIP-14 catalyst conforms to international standards and allows the production of diesel fuel with required cold flow properties under milder conditions (300°C against 320–325°C for the foreign catalyst) at a higher FHSV (3 h^?1 against 2 h^?1). The production of GIP-14 catalyst is planned to be launched in 2017.     

Upgrading coal-derived liquids to diesel fuel

Distilled fractions of a coal-derived liquid from the H-Coal process were upgraded to diesel fuel by catalytic hydrotreatment. The total hydrotreated products were distilled into naphtha (<180°C) and diesel fuel fractions (>180°C) and the diesel fractions were analysed for hydrocarbon-type composition, hydrogen content and some diesel fuel properties. GC—MS-analyses were carried out on the hydrocarbon-type fractions to identify individual chemical compounds. To investigate the effect of different distillation cut points on diesel fuel yield and properties, cut points for one hydrotreated product were varied. The diesel fuel cetane numbers were correlated with percentage hydrogen, total aromatics and saturates. Cetane numbers above 40 were obtained for diesel fuels containing (i) more than 75% saturates, (ii) less than 15% total aromatics and (iii) a hydrogen content above 12.8%. Compounds identified by GC—MS-analyses (in the diesel fractions) were typical aromatic and cycloparaffin compounds. Normal-and iso-paraffin compounds were not detected. By varying the distillation cut point from 135 to 180°C, the cetane number of the residual diesel fraction improved from 37 to 44. This increase is ascribed to the removal of aromatic compounds in the 135–180°C boiling point range.     

Degradation of single lap adhesively bonded composite joints due to hot water ageing

Joints, which are the most critical part of fibre-reinforced epoxy plastic structures, can be exposed to continuous hydrothermal action. In order to estimate their long-term performance, an accelerated ageing process was performed on adhesively bonded joints of glass-fibre-reinforced epoxy plastics with [0/90/45/?45]_s fibre orientations. Changes in the static tensile properties of single lap shear samples due to hot-wet exposure were investigated for one- and two-week immersion periods and at three different water temperatures (50°C, 70°C, and 90°C). Both the ageing temperature and immersion time were found to be influential on load–displacement characteristics, maximum failure loads, and apparent failure modes of joints bonded with Loctite Hysol-9466 epoxy type adhesive. Due to the hydrothermal exposure, maximum failure loads, distance to failure values, and stiffness of joints decreased by a certain amount in proportion to the immersion time and temperature. While unaged samples and those aged at 50°C and 70°C exhibited mainly light fibre-tear (LFT) failures, the samples treated at 90°C ruptured through the material cross section in stock-break (SB) failure mode.     

Effect of biodiesel on polyamide‐6‐based polymers

Biodiesel is considered one of the best alternative fuel sources in the transportation industry, but it has shown aggressive characteristics on materials that are used in fuel storage and delivery systems in vehicles. In this study, the effect of biodiesel (B100) on the properties of two polyamide‐6‐based semicrystalline polymers was studied and compared with that of diesel and a 20/80 blend of biodiesel and diesel (B20). Experiments were conducted using room temperature immersion tests in the three fuels for 720 h followed by postimmersion thermal and mechanical tests. In all three fuels, the polymers exhibited non‐Fickian weight increase during immersion and did not achieve equilibrium level of absorption in 720 h. The glass transition temperature (T_g), yield and tensile strengths, storage modulus, and peak tan δ decreased after immersion, while the degree of crystallinity and loss modulus increased. Fourier transform infrared spectroscopy study showed that no chemical changes occurred due to immersion. It is concluded that all three fuels absorbed into the polymers acted as plasticizers which caused the observed changes in the properties of the two polymers investigated in this research. POLYM. ENG. SCI., 59:1445–1454 2019. © 2019 Society of Plastics Engineers     

Properties of rapeseed oil for use as a diesel fuel extender

Chemical and thermal analyses were carried out on degummed and filtered (5 μm) rapeseed oil (referred to as SRO, i.e., semirefined rapeseed oil) to determine its suitability as a diesel fuel extender. The upper rate for inclusion of SRO with diesel fuel is 25%. This fuel blend had a phosphorus level of 2.5 ppm, which was comparable to rape methyl esters (1.0 ppm phosphorus). Thermogravimetric analyses were used to estimate the cetane ratings of the fuels. A 25% SRO/diesel blend had an estimated cetane index of 32.4 compared to 38.1 for diesel fuel only. Differential scanning calorimetry and thermogravimetric analyses were used to compare the volatility ranges of the fuels. SRO needed higher temperatures for volatilization (i.e., 70–260°C for diesel fuel vs. 280–520°C for SRO). This indicated poorer cold-starting performance of SRO compared with diesel fuel. SRO fuel is a low-sulfur, high-oxygen fuel giving SRO a more favorable emissions profile than pure diesel fuel.     

Catalytic reforming of hydrocarbon feedstocks into fuel for power generation units

The feasibility of realization of the multifuel operation principle, specifically, production of a hydrogen-containing gas from various types of hydrocarbon feedstocks using the same catalyst under similar reaction conditions is considered. The steam reforming of two types of hydrocarbon mixtures, namely diesel fuel satisfying GOST (State Standard) R 52368-2005 (EN 590:2004) and a methane-propane mixture imitating the composition of associated petroleum gas, has been investigated to clarify this issue. These hydrocarbon feedstocks were chosen for the reason that they are universally used as a fuel for various types of power generation units. Experiments have been carried out in a catalytic flow reactor at 250–480°C (for the methane-propane mixture) and 500–600°C (for diesel fuel) and pressures of 1–15 atm using a nickel-containing catalyst (NIAP-18). This catalyst has been demonstrated to ensure conversion of different types of hydrocarbon feedstocks into synthesis gas and methane-hydrogen mixtures usable as a fuel for power generation units based on high-temperature fuel cells and for spark-ignition, diesel, and gas-diesel engines.     

Wear behaviour of hydrogen free diamond-like carbon thin films in diesel fuel at different temperatures

In the present study, super hard, hydrogen free amorphous diamond-like carbons with a high fraction of sp³ hybridised carbon were deposited by pulsed laser deposition. The tribological performance of DLC coatings was investigated by translatory oscillating relative motion of a 100Cr6 steel ball in diesel fuel or ambient air at 25 °C or 150 °C temperature. The structure of the coatings and the tribological worn surfaces were characterised by Raman spectroscopy and by scanning electron microscopy. Bio-fuel with a high fraction of unsaturated fatty acids has the potential to reduce friction in tribological systems with chemically inert DLC. Diesel blend with 10% bio-fuel reduces friction at 150 °C. If there is no diesel fuel, pre-oxidation at 450 °C for 8 h leads to the best wear resistance (↓ f & wear rate) at room temperature. Without diesel fuel, enhancement of temperature up to 150 °C during wear testing causes an increase of the coefficient of friction. Again the 450 °C pre-oxidised sample revealed the lowest friction. For this coating, Raman spectroscopy points to a small increase of the sp² CC bonds. Diesel fuel seems to promote coherent coating failure under 150 °C wear, while pre-oxidation at 450 °C support adhesive coating ablation under higher loads or cyclic loading.     

Speed of sound and isentropic bulk modulus of alkyl monoesters at elevated temperatures and pressures

Biodiesel is a biodegradable, sulfur-free, oxygenated, and renewable alternative diesel fuel consisting of the alkyl monoesters of FA from vegetable oils and animal fats. Biodiesel can be used in existing diesel engines without significant modifications. However, differences in physical properties between biodiesel and petroleum-based diesel fuel may change the engine's fuel injection timing and combustion characteristics. These altered physical and chemical properties also may cause the exhaust emissions and performance to differ from the optimized settings chosen by the engine manufacturer. In particular, the density, speed of sound, and isentropic bulk modulus have a significant effect on the fuel injection system and combustion. The objective of this study was to measure these three properties for biodiesel (and the pure esters that are the constituents of biodiesel) at temperatures from 20 to 100°C and at pressures from atmospheric to 32.5 MPa. Ten different biodiesel fuels, 16 different pure FA esters, three hydrocarbons, and one diesel fuel were tested. The measured values of density, speed of sound, and isentropic bulk modulus are presented. Correlations between pressure and temperature are demonstrated. Speed of sound and isentropic bulk modulus tend to increase as the degree of unsaturation increases and as the chain length increases. However, density increased with shorter chain length and decreased with saturation.     

Thermal stability of polyoxymethylene and its blends with poly(ethylene‐methylacrylate) or poly(styrene‐butadiene‐styrene)

Polyoxymethylene (POM) copolymer and its blends with poly(ethylene‐methylacrylate) (EMA) or poly(styrene‐butadiene‐styrene) (SBS) up to 5 wt % were conducted to thermooxidative ageing in oven at 140°C for 111 days. POM showed continued degradation as seen from the gradual decrease in the crystallization temperature from differential scanning calorimetry (DSC) study, while no change in Fourier transform infrared spectra (FTIR) and low weight loss were observed (2.5% after 111 days' ageing). The POM degradation was characterized by the initial increase of crystallinity due to crystal perfection, which then kept nearly unchanged until 35 days' ageing, and lastly increased again to result in embrittlement and decrease in tensile strength. Increase in the tensile stress and strain was observed up to 35 days' ageing. POM blends with SBS or EMA had similar degradation behavior as POM, but addition of SBS accelerated the POM degradation significantly, while POM blend with 1 or 3% EMA just showed slightly lower thermal stability than POM. Degradation in POM and SBS/POM occurred in amorphous phase while EMA/POM degraded in both amorphous and crystal phase. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Artificial neural network model to predict cold filter plugging point of blended diesel fuels

Diesel fuel blending is an indispensable process in the diesel fuel producing process. It will benefit greatly the refineries to increase their profits if a mathematic model is developed to accurately estimate CFPP instead of substantial experiments. In this article, a back propagation artificial neural network model is established to predict CFPP of the blended diesel fuels, using input parameters of kinematics viscosity, density, refractivity intercept, CFPP and weight percentages of constituent diesel fuels. This model can give satisfactory predicting results for unknown diesel fuel samples either without PPD or with PPD and has been tested by practical industrial applications of produce blended diesel fuels. The mean predicting errors for the unknown samples without PPD are about 1.3 °C and about 2.5 °C for unknown samples with PPD.     

Evaluating Esters Derived from Mustard Oil (<Emphasis Type="Italic">Sinapis alba</Emphasis>) as Potential Diesel Additives

Biodiesel was produced from mustard oil utilizing transesterification with methanol, ethanol, propanol, and butanol to evaluate the characteristics of mustard biodiesel as an additive to regular diesel. Mustard oil was transesterified with alcohol at 6:1 alcohol to oil molar ratio, using KOH as a catalyst at 1 wt%. The maximum ester content achieved by this method was only 66%. Distillation was then used to purify the ester, raising the ester content to 99.8%. Alternatively, mustard oil methyl ester (MME) can be mixed with esters derived from canola oil or soybean oil to achieve an ASTM quality biodiesel. Biodiesel derived from mustard showed great potential as lubricity additive for regular diesel fuel. With an addition of 1% MME, lubricity of diesel fuel was improved by 43.7%. It is also found that methyl ester is the best lubricity additive among all esters (methyl-, ethyl-, propyl-, and butyl-ester). MME can be used at −16 °C without freezing whereas monounsaturated compounds (oleic, eicosenoic, and erucic esters) largely present in esters derived from mustard oil can tolerate −42 to −58 °C. Monounsaturated esters derived from higher alcohols such as butyl alcohol demonstrated a superior low temperature tolerance (−58 °C) as compared to that derived from lower alcohol such as methyl alcohol (−42 °C).     

A catalyst for producing diesel fuels with improved cold flow characteristics

The aim of this work is to develop a catalyst for the hydroisomerization of a straight-run hydrotreated diesel fraction to allow the production of a diesel fuel with improved cold flow characteristics. Some catalyst samples containing zirconia modified with tungstate anions, high-silica zeolite, noble (Pt, Pd) or transition (Ni, Mo) metals, a binder (alumina), and promotors are synthesized. The samples are subjected to laboratory tests at temperatures of 250–360°C, a pressure of 3.0 MPa, feed hourly space velocities (FHSVs) of 1.5–3.0 h^–1, and an H₂/feedstock ratio of 1000 m³/m³. The target product yield relative to feedstock on GITs-1 (with Ni, Mo) and GITs-2 (with Pt, Pd) is 84.6 and 91.0 wt %, respectively, and the depression of the cloud and cold filter plugging points in comparison to the feedstock was 20°C for both catalysts. The possibility of producing a diesel fuel for a cold climate in compliance with GOST R (Russian State Standard) 52368–2005 or a winter diesel fuel in compliance with TR TS (Customs Union Technical Regulation) 013/2011 is shown.     

Nitrophenoxy groups containing polybenzimidazoles as polymer electrolytes for fuel cells: Synthesis and characterization

Polybenzimidazoles containing different contents of pendant nitrophenoxy groups were prepared by condensation of 3,3′‐diamino‐benzidine with a mixture of 3,5‐dicarboxyl‐4′‐nitro diphenyl ether and isophthalic acid (IPA) in different ratios in polyphosphoric acid. The polymers are soluble in polar aprotic solvents, they have inherent viscosities in the range of 0.75–1.10 dL g^?1 and they form tough and transparent films on solution casting. They have good thermal stability with initial decomposition temperature ranging from 380 to 416°C in nitrogen, good tensile strength ranging from 56 to 65 MPa and reasonably good oxidative stability. Phosphoric acid uptake of these polymers is low compared with PBI and membranes doped with phosphoric acid exhibit good proton conductivity in the range of 6.6× 10^?3 to 1.9× 10^?2 S/cm at 25°C and 1.2× 10^?2 to 4.9× 10^?2 S/cm at 175°C, compared with 3.9× 10^?3 S/cm at 25°C and 3.2× 10^?2 S/cm at 175°C for PBI. These membranes are suitable for applications as polymer electrolyte for fuel cell and presumably for gas separation at high temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Cooling and annealing properties of copolymer-type polyacetals and its crystallization behavior

Copolymer-type polyacetals (POMs) that have been cooled at seven different rates from the melt at 180°C to the solid at 23°C show average spherulite diameters from 10 to 25 μm on an etched fracture surface using scanning electron microscopy (SEM). The wide-angle X-ray diffraction (WAXD) of POM displays a degree of crystallinity ranging from 60 to 66% by applying the two-phase model. From studies of mechanical properties, physical properties, and dielectric dissipation factor (tan δ), we found that POM with a faster cooling rate shows looser packing and smaller spherulites on the fracture surface than that with a slower cooling rate. This conclusion is in agreement with the observations made on SEM and WAXD. DSC measurements were used to measure the heat of fusion, melting point, and crystallization temperature of POMs. An equilibrium melting temperature was estimated from the Hoffman–Weeks plot. The overall crystallization kinetics of POMs were analyzed by the Avrami equation. Results for the Avrami exponent n, between 2 and 3, indicate small disklike spherulites following nucleation growth kinetics. Annealing the cooled POM at 150°C results in recrystallization featuring a significant increase in the average diameter of spherulites in SEM.     

Effect of hydrothermal environment on moisture absorption and mechanical properties of wood flour–filled polypropylene composites

The moisture absorption and mechanical properties of wood flour–filled polypropylene composites in a hydrothermal environment have been studied by immersing the composites in water at 23, 60, and 100°C. The degree of moisture absorption was found to be dependent on the modification of matrix, the weight percentage, mesh size, and surface treatment of wood flours. It increased with increasing the immersion temperature. The tensile strength of all composites with wood flours of different contents, mesh sizes, and surface treatments increased after immersion in water baths of various temperatures, to either greater or lesser extents. The flexural strength and modulus followed a similar trend when immersed in water at ambient temperature. However, the contrary was true for composites when immersed in 60 and 100°C water baths. The impact strength increased after immersion in water at each immersion temperature, and the extent of such increment decreased with increasing the immersion temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2824–2832, 2002     

Mechanical properties and microstructure changes of proton exchange membrane under immersed conditions

In this study, mechanical tensile stress–strain response and microstructure changes of proton exchange membranes (PEM) in immersed conditions are studied. The effects of water pretreatment and immersion time on stress–strain responses of Nafion^®?212 membranes are discussed. It is found that in the water immersion it took 24 h for the membrane to reach saturation equilibrium. Compared with dry membrane, immersed Nafion membrane shows a lower stress level at 30°C, but a higher stress level at 70°C. In situ small angle neutron scattering (SANS) experiments show that with the increase of temperature and water uptake, domains of the membrane become ordered and stay stable at around 60°C. Based on the observation, the relationship between the microstructure and mechanical properties is explained. POLYM. ENG. SCI. 54:2215–2221, 2014. © 2013 Society of Plastics Engineers     

Improvement of microstructures and properties of poly(lactic acid)/poly(ε‐caprolactone) blends compatibilized with polyoxymethylene

Incompatibility of poly(lactic acid)/poly(?‐caprolactone) (PLA/PCL) (80:20) and (70:30) blends were modified by incorporation of a small amount of polyoxymethylene (POM) (≤3 phr). Impact of POM on microstructures and tensile property of the blends were investigated. It is found that the introduction of POM into the PLA/PCL blends significantly improves their tensile property. With increasing POM loading from zero to 3 phr, elongation at break increases from 93.2% for the PLA/PCL (70:30) sample to 334.8% for the PLA/PCL/POM (70:30:3) sample. A size reduction in PCL domains and reinforcement in interfacial adhesion with increasing POM loading are confirmed by SEM observations. The compatibilization effect of POM on PLA/PCL blends can be attributed to hydrogen bonding between methylene groups of POM and carbonyl groups of PLA and PCL. In addition, nonisothermal and isothermal crystallization behaviors of PLA/PCL/POM (70:30:x) samples were investigated by using differential scanning calorimetry and wide angle X‐ray diffraction measurements. The results indicate that the crystallization dynamic of PLA matrix increases with POM loadings. It can be attributed to the fact that POM crystals have a nucleating effect on PLA. While crystallization temperature is 100 °C, crystallization half‐time can reduce from 9.4 to 2.0 min with increasing POM loading from zero to 3 phr. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46536.     

In situ studies on the temperature‐related deformation behavior of isotactic polypropylene spherulites with uniaxial stretching: The effect of crystallization conditions

The deformation behavior of isotactic polypropylene (iPP) spherulites with uniaxial stretching was investigated at different drawing temperatures via in situ polarized optical microscope (POM) observation. The iPP spherulites were prepared by two procedures: cooled to the room temperature from melt and annealed at 135, 140, and 145°C for 3 h. It was found that the crystallization conditions dominate the crystalline morphology and even the tensile properties of iPP. For iPP which crystallized during cooling progress, the spherulites were imperfect and the boundaries of the spherulites were diffuse, displaying good toughness at various drawing temperatures. For iPP annealed at high temperatures displayed the brittle fracture‐modes and the crack happened between spherulites, which due to the large and perfective spherulites have thick lamellas and weak connection at interspherulitic boundary. The shape and size of the iPP spherulites formed at 140 and 145°C are affected with uniaxial stretching till to the fracture of the samples at different drawing temperatures. The spherulites obtained at 135°C are deformed along the drawing direction at 100°C but not affected at low drawing temperatures, indicating the toughness increased with the increase of the drawing temperatures. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

The production of fatty acid isopropyl esters and their use as a diesel engine fuel

Biodiesel is an alternative fuel for diesel engines that consists of the monoalkyl esters of vegetable oils or animal fats. Currently, most biodiesel consists of methyl esters, which have poor cold-flow properties. Methyl esters of soybean oil will crystallize and plug fuel filters and lines at about 0°C. However, isopropyl esters have better cold-flow properties than methyl esters. This paper describes the production of isopropyl esters and their evaluation in a diesel engine. The effects of the alcohol amount, the catalyst amount, and two different catalysts on producing quality biodiesel were studied. Both sodium isopropoxide and potassium isopropoxide were found to be suitable for use in the transesterification process. A 20∶1 alcohol/TG molar ratio and a catalyst amount equal to 1% by weight (based on the TG amount) of sodium metal was the most cost-effective way to produce biodiesel fuel. The emissions from a diesel engine running on isopropyl esters made from soybean oil and yellow grease were investigated by comparing them with No. 2 diesel fuel and methyl esters. For nitrogen oxide emission, the difference between the biodiesel produced from soybean oil and yellow grease was greater than the difference between the methyl and isopropyl esters of both feedstocks. The other emissions from using isopropyl esters were about 50% lower in hydrocarbons, 10–20% lower in carbon monoxide, and 40% lower in smoke number when compared with No. 2 diesel fuel.