Synthesis and Physical Properties of Tallow-Oleic Estolide 2-Ethylhexyl Esters

Tallow-oleic estolide 2-ethylhexyl (2-EH) esters were synthesized in a perchloric acid catalyzed one-pot process from industrial 90% oleic and tallow fatty acids at various ratios, while varying the ratio of tallow and oleic fatty acids, with the esterification process incorporated into an in situ second step to provide a functional fluid. Their viscosities ranged 57–80 cSt at 40 °C and 10.8–14.0 cSt at 100 °C with viscosity index (VI) 169–185. The 100% tallow estolide 2-EH ester had modest low-temperature properties (pour point = −15 °C and cloud point = −14 °C), while the 50:50 mixture of oleic and tallow fatty acids produced an estolide that had better low-temperature properties (pour point = −21 °C and cloud point = −21 °C) without a large negative effect on the oxidative stability. The oxidative stability increased as the amount of saturation increased (rotating pressurized vessel oxidation test (RPVOT) × 165–274 min). The tallow-oleic estolide 2-EH esters have shown remarkably low evaporative losses of only 1% loss compared to a 15–17% loss for commercial materials of similar viscosity grade. Along with expected good biodegradability, these tallow-oleic estolide 2-EH esters had acceptable properties that should provide a specialty niche. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Synthesis of Dimer Acid 2-Ethylhexyl Esters and their Physicochemical Properties as Biolubricant Base Stock and their Potential as Additive in Commercial Base Oils

Previously synthesized C36-dimer acids (DA) have been esterified (97 ± 0.2% conversion at 120 °C for 72 hours) with 2-ethylhexanol (2-EH) to produce a new class of C52-DA 2-EH esters that have potential application in biolubricant formulations such as base oils and additives. Investigation of physicochemical and lubricant properties showed the bio-based esters have good solubility in commercial base stocks such as polyalpha olefin (PAO-6) (>20 w/w) and high-oleic sunflower oil (HOSuO) (>20 w/w). The neat C52-DA 2-EH esters displayed a three- to eightfold higher kinematic viscosity and comparable viscosity index (VI = 134) as a commercial base stock, PAO-6 (VI =137). Both C52-DA 2-EH esters, whose parent C36-DA were synthesized with two different zeolite catalysts, were oxidatively stable above 176 °C. Blending C52-DA 2-EH esters in HOSuO improved the pour point (PP) of HOSuO from −18.8 to −21.0 °C at 1% w/w and the cloud point (CP) from −6.3 to −10.6 °C at 8% w/w of C52-DA 2-EH ester 1. A similar trend was observed for C52-DA 2-EH ester 2, indicating that the esters possess PP depressant (PPD) characteristics in HOSuO blends. Blending C52-DA 2-EH esters in PAO-6 increased the VI of PAO-6, which is an indication that the bio-based esters were acting as VI improvers (VII). It was concluded that C52-DA 2-EH esters can be employed commercially as bio-based base oils and as PPD and VII additives in lubricant formulations.     

Comparative Assay of Antioxidant Packages for Dimer of Estolide Esters

A series of 26 different antioxidants and commercial antioxidant packages designed for petroleum‐based materials, containing both natural and synthetic‐based materials, were evaluated with dimeric coconut‐oleic estolide 2‐ethylhexyl ester (2‐EH), a bio‐based material. The different antioxidants were categorized into different classes of phenolic, aminic, and blended/others materials. The oxidation onset temperatures (OT) using non‐isothermal pressurized differential scanning calorimetry (PDSC) were measured and recorded under previously reported standard conditions. The aminic series gave the best resistance to oxidation as defined by the PDSC method with OT of 246.6 and 244.7 °C for the best two performers, which was a 38 °C improvement over the uninhibited or unformulated dimer estolide material. The phenolic series, containing most of the naturally occurring antioxidants, was the least successful formulation package for the dimer estolide. The blended/other materials, which were specifically designed for petroleum‐based lubricants, did not have the best OT, since the estolides and other bio‐based materials interact differently than their petroleum counterparts. A number of potential antioxidants have been identified as useful additives for the estolides esters. The OT of the estolide and formulated materials correlated well with other bio‐based materials such as biodiesel.     

Investigation of the Physical and Tribological Properties of Iso-Oleic Acid

Oleic acid was isomerized into iso-oleic acid using a modified ferrite zeolite catalyst. The isomerization produced a mixture of iso-oleic acid isomers, with a methyl branching at the double bond, whose position has been randomly distributed along the fatty-acid chain. The effect of isomerization on the physical and tribological properties of iso-oleic acid relative to oleic acid was investigated. The neat fatty acids and their blends in polyalphaolefin (PAO-6) and high-oleic sunflower oil (HOSuO) base oils were used in the investigations. Relative to neat oleic acid, neat iso-oleic acid displayed: higher kinematic viscosity but lower viscosity index (VI) and acid number; lower pour point (PP) and cloud point (CP); better oxidation stability; similar four-ball (4-ball) antiwear friction and wear; and similar 4-ball extreme pressure weld point. Blends (0–10%, w/w) of iso-oleic and oleic acid in PAO-6 displayed the following similar trends with increasing concentration: mildly decreasing kinematic viscosity at 40 and 100 °C; increasing VI; lower coefficient of friction; and no change in wear. Blends (0–10%, w/w) of iso-oleic and oleic acid in HOSuO displayed the following similar trends: decreasing oxidation stability with increasing concentration; constant PP and CP with increasing concentration.     

The Effect of Branched-Chain Fatty Acid Alkyl Esters on the Cold-Flow Properties of Biodiesel

Biodiesel (fatty acid methyl esters [FAME]) is produced from various fats, oils, and greases (FOG) using catalytic transesterification with methanol. These fuels have poor cold-flow properties depending on the fatty acid (FA) composition of the parent FOG. Improving the cold-flow properties of biodiesel will enhance its prospects for use during cooler months in moderate temperature climates. This work is a study on the use of skeletally branched-chain alkyl esters (BCAE) composed of the isopropyl, n-butyl, and 2-ethylhexyl esters of iso-oleic acid isomers (iPr-iOL, nBu-iOL, and 2EH-iOL). These BCAE additives were tested in blends with linear-FAME (L-FAME) derived from soybean oil (SME), lard (LME), tallow (TME), and sewage scum grease (SGME). Binary L-FAME/SME admixtures were also studied. Admixtures were tested for the effects of the additives on cloud point (CP), pour point (PP), and kinematic viscosities at standard (ν⁴⁰ = 40 °C) and low temperatures (T_L) = CP + 5 °C (ν^L). Although the BCAE additives were more effective than SME, relatively large additive concentrations (y_Add) were needed to depress CP and PP by more than 2 °C. Admixtures with high concentrations of BCAE additive had ν⁴⁰ > 6.0 mm² s⁻¹, the maximum limit in ASTM fuel specification D 6751. While the iPr-iOL and nBu-iOL additives may be blended at concentrations up to y_Add = 0.50, 2EH-iOL should not exceed y_Add = 0.28 in LME, 0.31 in SGME, 0.35 in TME, or 0.41 in SME to avoid driving the admixture out of specification. Some anomalies observed in the results at low y_Add for SGME/BCAE admixtures were speculated to have been affected by the low-temperature rheology of SGME.     

Synthesis and Physicochemical Properties of Low Viscosity 2-Ethylhexyl Alkyl Ethers Made from Palm-Based Esters as Potential Biolubricant

A series of 2-ethylhexyl alkyl ethers (EHAE) are synthesized from palm-based esters via a one-step reaction under mild reaction conditions for potential usage as biolubricant. In this work, 2-ethylhexyl esters with varying fatty acid chain lengths are reacted with 1,1,3,3-tetramethyldisiloxane (TMDS), catalyzed by indium bromide (InBr₃) at 40 °C to afford EHAE with lauryl, palmityl, stearyl, and oleyl alkyl chain with 55–68% isolated yield. These compounds are characterized using Fourier-transform infrared (FTIR) and NMR spectroscopic methods and are evaluated for their viscosity, thermal, cold-flow, oxidative, and anti-wear properties. The synthesized EHAEs demonstrate low viscosity (1.65–2.55 cSt at 100 °C) with excellent viscosity indices (130–182). These EHAEs show comparable wear scar diameter (0.6–1.0 mm) in comparison with commercial mineral oil base stock (group I SN150) in the four-ball wear test. Thermal-oxidative investigation of the EHAE reveals that the thermal degradation temperatures are in the range of 200–250 °C and oxidation onset temperatures are between 165 and 184 °C. Among the EHAEs, 2-ethylhexyl lauryl ether with the shortest alkyl chain has the lowest pour point of ?27 °C. The physicochemical properties of synthesized EHAEs indicate that they are potential as biolubricant base stocks. Practical Applications : The EHAEs produced from this work exhibit promising physicochemical and lubricity properties, which offer great potential to be used as lubricant base stock especially for internal engine oil application.     

Diesters from Oleic Acid: Synthesis,Low Temperature Properties,and Oxidation Stability

Several diesters were prepared from commercially available oleic acid and common organic acids. The key step in the three step synthesis of oleochemical diesters entails a ring opening esterification of alkyl 9,10-epoxyoctadecanoates (alkyl: propyl, isopropyl, octyl, 2-ethylhexyl) using propionic and octanoic acids without the need for either solvent or catalyst. Each synthetic diester was evaluated for both low temperature operability and oxidation stability through measurement of cloud point, pour point, oxidation onset temperature, and signal maximum temperature. It was discovered that increasing chain length of the mid-chain ester and branching in the end-chain ester had a positive influence on the low temperature properties of diesters. Improved oxidation stability is achieved when the chain length of the mid-chain ester is decreased. Additionally, the mid-chain ester plays a larger role in oxidation stability than the end-chain ester. These products may prove useful in the search for bio-based industrial materials, such as lubricants, surfactants, and fuel additives. Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Synthesis of polymeric pour point depressants for Nada crude oil (Gujarat,India) and its impact on oil rheology

Five flow improvers have been synthesized to study rheological properties of Nada crude oil (Gujarat, India). Anhydride copolymers were prepared making use of the copolymerization of acrylates of different alkyls with maleic anhydride and the Poly (n-alkyl acrylates-co-N-hexadecylmaleimide) were prepared by the reaction of copolymer with hexadecylamine. The additives were purified and characterized by FTIR, GPC. The prepared polymeric additives shows dual function both as wax dispersants and flow improvers and all of them acts as good pour point depressants. Yield stress and the viscosity of the crude oil at different temperatures and concentrations of additives were evaluated by zero friction advanced rheometer AR-500 of TA instrument. Comparison of morphologies and structures of wax crystals or aggregates in waxy crude oils beneficiated with and without a PPD was also done by micro photographic studies which show the modification in wax crystal morphology due to additives.     

Branched‐Chain Fatty Acid Methyl Esters as Cold Flow Improvers for Biodiesel

Biodiesel is an alternative diesel fuel derived mainly from the transesterification of plant oils with methanol or ethanol. This fuel is generally made from commodity oils such as canola, palm or soybean and has a number of properties that make it compatible in compression‐ignition engines. Despite its many advantages, biodiesel has poor cold flow properties that may impact its deployment during cooler months in moderate temperature climates. This work is a study on the use of skeletally branched‐chain‐fatty acid methyl esters (BC‐FAME) as additives and diluents to decrease the cloud point (CP) and pour point (PP) of biodiesel. Two BC‐FAME, methyl iso‐oleate and methyl iso‐stearate isomers (Me iso‐C_18:1 and Me iso‐C_18:0), were tested in mixtures with fatty acid methyl esters (FAME) of canola, palm and soybean oil (CaME, PME and SME). Results showed that mixing linear FAME with up to 2 mass% BC‐FAME did not greatly affect CP, PP or kinematic viscosity (ν) relative to the unmixed biodiesel fuels. In contrast, higher concentrations of BC‐FAME, namely between 17 and 39 mass%, significantly improved CP and PP without raising ν in excess of limits in the biodiesel fuel standard specification ASTM D 6751. Furthermore, it is shown that biodiesel/Me iso‐C_18:0 mixtures matched or exceeded the performance of biodiesel/Me iso‐C_18:1 mixtures in terms of decreasing CP and PP under certain conditions. This was taken as evidence that additives or diluents with chemical structures based on long‐chain saturated chains may be more effective at reducing the cold flow properties of mixtures with biodiesel than structures based on long‐chain unsaturated chains.     

掺混型生物柴油低温流动性研究进展

生物柴油的低温流动性能主要由生物柴油中饱和脂肪酸甲酯的组成、含量和支链程度决定,冷凝点一般为0 ℃左右,其低温结晶和凝胶化限制了生物柴油在天冷季节的使用.生物柴油作为柴油机燃料油一般与石化柴油按一定比例勾兑为掺混油使用.着重论述了国内外针对掺混型生物柴油低温降凝方面所做出的探索,并对前人提出的关于生物柴油降凝剂的研究作了简要评述.     

Tribological Properties of Biobased Ester Phosphonates

Three phosphonate derivatives of methyl oleate (MeO) were chemically synthesized in a radical chain reaction and their physical and tribological properties investigated. The phosphonates differed from each other in the structure of the alkoxy groups attached to the phosphorous, which were as follows: methoxy, ethoxy, and n-butoxy. Phosphonylation eliminated the unsaturation in MeO and also introduced branching. The phosphonate oils had higher density and viscosity than MeO, which was attributed to the contribution of the heavier phosphorus atom in their structures, and to their higher molecular weights, respectively. The phosphonates also displayed improved oxidation stability and cold flow properties, which were attributed to the elimination of the double bond and the introduction of branching in their molecular structures, respectively. Tribological investigations were conducted using 4-Ball anti-wear (AW) and extreme pressure (EP) methods. Neat phosphonates displayed lower AW coefficients of friction and wear scar diameters than MeO. The improved AW results were attributed to the higher viscosity of the phosphonates, since the AW test is conducted in the mixed film regime. The phosphonates had no effect on EP weld point (WP) as neat oils or as 5 % additives in petroleum-based oils. In soy base oil, 5 % phosphonate additives displayed smaller improvement in WP than zinc dialkyl dithiophosphate (ZDDP). It is proposed that this lack of EP characteristics could be due to the high dissociation energy of C–P bonds in the phosphonates, compared to, for example, S–P bonds in ZDDP.     

Mono‐Estolide Synthesis from trans‐8‐Hydroxy‐Fatty Acids by Lipases in Solvent‐Free Media and Their Physical Properties

Pseudomonas aeruginosa 42A2 is known to produce two hydroxy‐fatty acids, 10(S)‐hydroxy‐8(E)‐octadecenoic and 7,10(S,S)‐dihydroxy‐8(E)‐octadecenoic acids, when cultivated in a mineral medium using oleic acid as a single carbon source. These compounds were purified, 91 and 96 % respectively, to produce two new families of estolides: trans‐8‐estolides and saturated estolides from the monohydroxylated monomer. trans‐8‐estolides were produced by three different lipases (Novozym 435, Lipozyme RM IM and Lipozyme TL IM) with reaction yields between 68.4 ± 2.1 and 94.7 ± 2.4 % in a solvent‐free medium at 80 °C in 168 h under vacuum. Novozym 435 was found to be the most efficient biocatalyst for both hydroxy‐fatty acids with reaction yields of 71.7 ± 2.3 and 94.7 ± 2.4 %, respectively. Moreover, saturated estolides were also produced from a saturated 10(S)‐hydroxy‐8(E)‐octadecenoic. These estolides were chemically and enzymatically synthesized with Novozym 435, under the previous described reaction conditions with yields of 60.7 ± 2.1 and 71.2 ± 2.3 % respectively. Finally, viscosity, glass transition temperature, decomposition temperatures and enthalpies were determined to characterize both types of estolides. Thermal applications for both types of polyesters were improved since glass transition temperatures were lowered and decomposition temperatures were increased, with respect to their corresponding substrates.     

光催化纳米CdS复合TiO2薄膜的表面形貌及太阳光光催化性能

采用禁带宽度较窄的CdS与TiO2进行复合,形成复合光催化纳米薄膜,可使自洁净玻璃的太阳光光催化效率大大提高.以溶胶-凝胶法,通过旋转涂膜工艺在玻璃表面制备CdS复合TiO2薄膜.利用SEM研究玻璃表面复合薄膜的形貌,电子能谱研究玻璃表面薄膜成分,并且利用高效液相色谱和可见光分光光度计测定薄膜对油酸、醋酸等有机物的太阳光光催化降解效率.     

A Predictive Correlation for Dynamic Viscosity of Fatty Acid Methyl Esters and Biodiesel

The viscosity of biodiesel, which is a mixture of fatty acid methyl esters (FAME), is an important physical property in the injection and efficient combustion. In this study, a simple correlation, with only one adjustable parameter, is proposed for predicting the viscosity of FAME and their mixtures (biodiesel) as a function of temperature. First, the adjustable parameter of the correlation is calculated for various FAME. The average absolute relative deviation (AARD) is obtained to be 0.97% for 226 data points. Second, the adjustable parameter of FAME is connected to the number of carbon atoms and the number of double bonds to build a predictive correlation for the calculation of viscosity. The AARD for 226 data points is obtained to be 2.28%. Third, the proposed model is employed to predict the viscosity of biodiesel without introducing any new adjustable parameter. To predict the viscosity of biodiesel, the average of the adjustable parameter is applied to the correlation. The AARD of 2.96% is obtained for 185 data points comprised of 23 different biodiesels. To better understand the ability of the correlation in the estimation of the viscosity of biodiesel and FAME, a comparison is made between the present correlation and a number of correlations available in the literature.     

-35#低凝柴油的研制

介绍了-35^#低凝柴油的研制方法,对国内外不同种类的降凝剂的加剂量和降凝效果进行了分析和讨论,得出了最佳调配方案。并探讨了调合组分的不同配比对提高降凝剂降凝效果的影响。     

高黏度尼龙6膜的制备与性能研究

采用由阴离子淤浆聚合法制备的高黏度尼龙6为原料，以甲酸为溶剂制备溶液。考察温度与树脂相对黏度对溶液黏度的影响，同时用流延法制膜，研究树脂相对黏度和温度对膜力学性能的影响。结果表明，高黏度尼龙6溶液的黏度可达400Pa·s左右，随着温度的升高，尼龙6溶液的黏度降低，在同一温度下，溶液的黏度随树脂相对黏度的升高而增大。高黏度尼龙6膜的力学性能如模量、屈服应力、最大负荷、断裂强度随着树脂相对黏度的增大和膜处理温度的升高而增加。     

An Empirical Equation for Estimation of Kinematic Viscosity of Fatty Acid Methyl Esters and Biodiesel

Kinematic viscosity (µ) is an important physical property of fatty acid methyl esters (FAME) and biodiesel. In this work, the Martin's rule of free energy additivity is extended to cover the kinematic viscosity of saturated and unsaturated FAME commonly found in nature. The proposed model can also be extended to estimate kinematic viscosity of biodiesel. The kinematic viscosity of a FAME or a biodiesel can be easily estimated from its carbon number (z), number of double bonds (n_d) at different temperatures (T) without a prior knowledge of the viscosity of individual FAME. Both z_ave and n_d(ave) can be derived from its fatty acid composition. Thus, kinematic viscosity of biodiesel at temperatures between 20 and 100 °C and at atmospheric pressure can be estimated. The average absolute deviation (AAD) estimated at 20–100 °C for saturated, unsaturated FAME, biodiesels and biodiesel blends are 4.15, 3.25, 6.95 and 2.79 %, respectively. The biodiesels collected in this study (191 data points) have the z_ave and n_d(ave) between 14.10 and 17.96 and 0.21–1.54, respectively. The standard deviation was 0.249. The proposed model would be good for estimation of viscosity of biodiesel containing normal fatty acids, generally found in biodiesel feed stocks.     

PPE黏度对MPPE性能的影响

采用双螺杆挤出,在相同工艺条件下制备了四种改性聚苯醚(MPPE)产品,研究了不同特性黏度的聚苯醚(PPE)对MPPE性能的影响.结果表明:随着PPE黏度的增加,MPPE的力学性能明显提高,耐热性能有较大改善;但熔体流动速度变慢,成型加工性能有所降低.     

生物柴油降凝机理的研究进展

生物柴油是可再生清洁燃料,能够减缓人类对石化柴油的依赖,然而生物柴油凝固点和粘度相对较高,低温流动性较差,冬季低温环境下结晶体易堵塞发动机管道和过滤器,使发动机无法正常工作。主要综述了生物柴油的性质、特点、降凝剂的作用机理及其研究方法。并对生物柴油的前景做了展望。