Compositions of commercial corn and soybean lecithins

The lipid and fatty acid compositions of commercial corn and soybean lecithins were compared. The types of lipids were similar, but the proportions varied. The ratio of glycolipids to phospholipids was 0.36 for corn lecithin and 0.14 for soybean. Phosphatidylcholine and phosphatidylinositol were major phospholipids in both lecithins. In soybean lecithin, the percentage of phosphatidyleth-anolamine equaled that of phosphatidylinositol, but in corn, the percentage of phosphatidylethanolamine was only about one-fourth the percentage of phosphatidylinositol. High levels of phosphatidic acid in both the corn and soybean preparations indicated some degradation of the phospholipids during processing. The major differences in fatty acid compositions were a higher percentage of oleic acid and lower percentages of stearic and linolenic acids in corn compared to soybean. The lower level of linolenic acid should give corn lecithin greater resistance toward autoxidation and the development of off-flavors.     

Study on thermal decomposition characteristics and kinetics of soybean

In this paper, the thermal degradation kinetics of soybean was studied by dynamic thermogravimetry (TGA). The thermal decomposition characteristics and kinetics of soybean under different pyrolysis conditions were explored by changing the heating rate (5, 10, 20 and 40℃/min) and the atmosphere conditions (nitrogen and air). According to the trend of TGA and DTG curves, the pyrolysis of soybean can be divided into four stages: the first two stages correspond to the removal of free water and crystal water, and the last two stages correspond to the secondary decomposition stage and the main decomposition stage of main components (starch, protein and fat). In the latter two stages, due to the presence of oxygen, the thermal decomposition process of soybean appeared different, and the activation energy and carbon residue rate of the reaction decreased. Compared with pyrolysis in nitrogen atmosphere, soybean showed lower activation energy and fire safety in air atmosphere. In this paper, the difference of pyrolysis kinetics of soybean in different atmosphere was studied for the first time, and the intrinsic law of pyrolysis and its fire safety were revealed.     

大豆的热分解特性及其动力学探究

动态热重分析（TGA）被用来研究大豆的热降解动力学,通过改变大豆热解时的升温速率（5,10,20和40℃/min）以及气氛条件（氮气和空气）探索了大豆在不同热解条件下的热解特性。并结合对相应热解条件下的动力学参数（表观活化能E_k）进行求解,探究了大豆的火灾安全性。结果表明,大豆的热解可以分为四个阶段：前两个阶段对应自由水和结晶水的脱除,后两个阶段对应主要成分（淀粉、蛋白质和脂肪）的次分解阶段和主要分解阶段。后两个阶段,由于氧气的存在,导致大豆的热分解出现了不同的历程,800℃时的残炭率降低。且与氮气气氛下热解相比,大豆在空气气氛下表现出更低的反应活化能和火灾安全性。     

Diesel fuel from thermal decomposition of soybean oil

Soybean oil was thermally decomposed and distilled in air or in nitrogen sparge with standard ASTM distillation apparatus. GC-MS analysis showed that approximately 75% of the products were made up of alkanes, alkenes, aromatics and carboxylic acids with carbon numbers ranging from 4 to more than 20. Fuel properties of the pyrolyzed materials were characterized and compared with those of the parent oil. The pyrolyzates had lower viscosities and higher cetane numbers than the parent vegetable oil. Thermally decomposed soybean oil shows promise as alternative fuel for the direct-injection diesel engine. Presented at the AOCS meeting in New Orleans, LA, in May 1987. Address all correspondence to Marvin O. Bagby, NRRC, ARS/USDA, 1815 N. University St., Peoria, IL 61604. Deceased.     

Gram-scale preparative HPLC of phospholipids from soybean lecithins

A preparative procedure has been developed to isolate gram quantities of phospholipid classes from soybean lecithins. Various steps taken to accomplish the isolation are described—an analytical method with silica column and light scattering detector, alcohol fractionation of deoiled lecithins, and columns with increasing internal diameters but packed with the same stationary phase. The loading study showed that it was possible to inject 20 mg on a 100 × 8 mm RadialμPorasil colume. The separation was scaled up to a 25-mm i.d. column and finally to a 50-mm i.d. column. With the larger column, 2.1 g of phospholipids were separated. The collected fractions (phosphatidylethanolamine, phosphatidylinositol, phosphatidic acid and phosphatidylcholine) were of high purity (>99%). The solvent consumption was 7.2 L (separation and column equilibration), and a minimum of 10 g of polar lipids can be separated daily. Presented at the 82nd American Oil Chemists’ Society Annual Meeting, May 13–15 1991, Chicago, IL.     

The thermal decomposition of polyurethanes and polyisocyanurates

The thermal decomposition of a number of TDI- and MDI-based biscarbamates (model compounds for polyurethane foams) between 200°C and 1000°C showed that the urethane linkage undergoes an O-acyl fission at about 300°C to generate the free isocyanate and alcohol. In the case of the flexible foam analogues, the newly generated TDI reacts further to generate volatile polyureas, termed ‘yellow smoke’. The MDI residues generated in the decomposition of a rigid foams react to yield non-volatile polycarbodiimides. Both the yellow smokes and the polycarbodiimides decompose above 600°C to give a mixture of nitriles (including HCN) as well as a number of olefinic and aromatic compounds. The use of ¹³C labeling indicated that HCN and all the other nitriles generated during the high temperature decompositions originate in the thermal fission of the aromatic ring, the nitrile carbon being the 2-, 4- or 6- carbon of MDI.     

Synthesis,characterization, and kinetics study of thermal decomposition of epoxidized soybean oil acrylate

The synthesis of epoxidized soybean oil acrylate (ESOA) from epoxidized soybean oil (ESO) had been carried out by reacting acrylic acid with the oxirane group in ESO. The acrylated ESO products were characterized using a variety of analytical techniques. The oxygen value, iodine value, and acid value were obtained to know the amount of unsaturation in the synthesized product. Infrared and proton NMR spectra were carried out to confirm the participation of oxirane group in the acrylation reaction. Free‐radical initiators, benzoyl peroxide and tertiary butyl peroxy benzoate, were used for the curing of ESOA resin. Thermal decomposition kinetics of ESOA was studied by the methods of Ozawa, Kissinger, and Horowitz‐Metzger, and the kinetic parameters were compared. The thermal decomposition data of the cured ESOA resin was analyzed by thermogravimetric analysis (TGA) at different heating rates. TG curves showed that the thermal decomposition of the ESOA system occurred in one stage. The apparent activation energies determined by the Ozawa, Kissinger, and Horowitz‐Metzger methods are 122.69, 95.347, and 126.20 kJ/mol, respectively. The results show that there was a reasonably good agreement between the calculated activation energies for stage one in the above methods. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The thermal decomposition of sulfenamide accelerators

The thermal decomposition of three sulfenamide accelerators N-cyclohexylbenzothiazole sulfenamide (CBS), 2-(4-morpholinothio) benzothiazole (MOR) and 2-t-butylaminobenzothiazole sulfenamide (TBBS) were investigated by differential scanning calorimetry. The sulfenamides decompose rapidly at 210–220°C, yielding a number of products, including reactive polysulfidic complexes. Thus, CBS gives N-cyclohexylamino-2-benzothiazole polysulfides (CBP), 2-bisbenzothiazole-2,2′-disulfide (MBTS), 2-bisbenzothiazole-2,2′-polysulfides (MBTP), 2-bisbenzothiazole-2,2′-monosulfide (MBTM), 2-mercaptobenzothiazole (MBT), and 2-N-cyclohexylaminobenzothiazole (CB). The polysulfides are unstable, and on prolonged heating, only MBT and CB remain. The amine fragment of the accelerator is present as the amine salt of MBT. At lower temperatures, the sulfenamides are relatively stable. MOR forms an analogous product spectrum. The decomposition of TBBS is endothermic, in contrast to the exothermic reaction observed with CBS and MOR, and the concentrations of the various polysulfides do not decrease on prolonged heating. Reaction mechanisms are proposed to account for the formation of the products. © 1994 John Wiley & Sons, Inc.     

Influence of dietary soybean and egg lecithins on lipid responses in cholesterol-fed guinea pigs

The comparative influence on plasma and tissue lipids of dietary soybean and egg lecithins, which have contrasting fatty acid compositions, was studied in the hypercholesterolemic guine apig. The polyunsaturated to saturated fatty acid (P/S) ratios of the soybean and egg lecithins were 3.4 and 0.38, respectively. Hypercholesterolemia was induced by feeding guinea pigs a purified diet that contained 15% lard enriched with 0.5% cholesterol. Subsequently, guinea pigs were fed for six wk the same diet supplemented with either soybean or egg lecithin as 7.5% of the diet. A control group continued to be fed the lecithin-free diet. Parameters measured included body weight and relative liver weight; in plasma, total cholesterol, high density lipoprotein cholesterol (HDLC), phospholipid, and nonesterified cholesterol; in liver, total fat, cholesterol, and the specific activity of the catabolic enzyme cholesterol 7α-hydroxylase; (EC 1.14.13.17); and in the aorta, cholesterol. Among the most noteworthy observations were the 49% decrease in total plasma cholesterol of the soybean lecithin group without decreasing HDLC and the 177% increase in HDLC of the egg lecithin group without a significant increase in total cholesterol compared with those values in the control group. These data suggest that dietary lecithin is particularly effective in increasing the HDLC/total cholesterol ratio in plasma. However, the absolute concentrations of those plasma lipids seem to depend upon the fatty acid composition of the lecithin. Presented in part at the annual meeting of the American Oil Chemists' Society, New Orleans LA, May 1987.     

The attapulgus clay-catalysed thermal decomposition of terphenyls

The kinetics of the pyrolysis of pure o-, m- and p-terphenyl and of material mixed with Attapulgus clay were studied. 10 to 12 times more o-, m- and p-terphenyl was decomposed in the clay-catalysed experiments and a strong isomerisation of o- into m- and p-, and m- into p-terphenyl appeared. Twice as much benzene and biphenyl was formed, in the runs to which clay had been added. Similar differences were obtained for the quaterphenyl, triphenyl and triphenylbenzene formations. From the catalysed experiments 50 times as much total gas was found consisting of 41% hydrogen, 19% methane, 7% ethane, 2% propane, 1·5% n-pentane, 3·8% isopentane, 2·5% ethylene, 0·4% acetylene, 0·9% propene and 32% butenes. The uncatalysed runs yielded 82% hydrogen, 4% methane, 1% ethane, 0·4% propane 0·2% n-pentane, 0·3% isopentane, 10% ethylene, 2·8% acetylene, 1·2% propene and 2% butenes. It is suggested that the thermal decomposition of pure terphenyls follows a radical mechanism while the clay-catalysed pyrolysis follows a carbonium ion mechanism.     

The thermal decomposition of some polyurethane foams

Polyurethanes exposed to fire conditions might generate decomposition products which would be responsible for a significant part of the toxicity of the fire gases. Polyurethanes have been prepared from a commercial mixture of tolylene-2, 4- and 2,6-di-isocyanates, pure tolylene-2,4-di-isocyanate, pure tolylene-2,6-di-isocyanate and pure m-phenylene di-isocyanate. All polymers except that prepared from tolylene-2,6-di-isocyanate were obtained as flexible foams. When each polyurethane was heated at 300°C in a stream of nitrogen, a sublimate was obtained. The sublimates were all apparently polymers derived from the di-isocyanate rather than from the diol constituents of the polyurethanes. Pyrolysis of these materials at high temperatures (800–1000°C) led to similar mixtures of volatile products: at 1000°C the most abundant nitrogenous product, in each case, was hydrogen cyanide.     

The thermal decomposition of some tolylene bis-carbamates

In fires, flexible polyurethane foams can decompose to give smokes which are subsequently degraded with the generation of hydrogen cyanide. In order to understand the general nature of this hazard it is first necessary to obtain information about the decomposition mechanism of the polyurethane foams and the structures of the intermediate smokes. The complexity of this problem has required the use of suitable model compounds. The preparation is described of (i) the four bis-carbamates based on pure tolylene 2, 4-diisocyanate and pure tolylene 2,6-di-isocyanate, each in combination with 2-ethoxyethanol and with triethylene glycol monomethyl ether, and (ii) a urethane-carbodi-imide-urethane and a urethane-urea-urethane based on pure tolylene 2,6-di-isocyanate and 2-ethoxyethanol. All were decomposed by heating under nitrogen at temperatures near 300°C. The two di-2-ethoxyethyl bis-carbamates ( la and IIa ) gave volatile monoisocyanate-monourethanes and 2-ethoxyethanol. The two di-2-[2-(2-methoxyethoxy)ethoxy] ethyl bis-carbamates ( Ib and IIb ) gave corresponding products and residue which contained carbodi-imide functions. The urethane-carbodi-imide-urethane ( Va ) gave a volatile urethane-carbodi-imide-isocyanate ( Via ) and 2-ethoxyethanol. The urethane-urea-urethane ( VIIIa ) decomposed through isocyanate- and carbodi-imide-containing materials to a volatile polymeric urea, which was obtained as a smoke and appeared to be virtually identical with the smoke obtained in earlier work from a commercial polyurethane. These results suggest that poly-urethanes based on tolylene di-isocyanate and polyether polyols decompose, when heated under nitrogen at 300°C, by cleavage of urethane groups to regenerate isocyanate groups and liberate alcohols. The isocyanato groups may react either with other isocyanato groups to give carbodi-imides, which are then rapidly hydrated to ureas, or with water to give amines, which react with other isocyanato groups again to give ureas. Whether these processes occur separately or together, the ultimate product at 300°C, i.e. the smoke, will be a polymeric urea.     

Analysis of soybean lecithins and beef phospholipids by HPLC with an evaporative light scattering detector

Linear (r > 0.99) calibration curves were obtained for 10–150 μg of phosphatidylethanolamine (PE), 10–75 μg of phosphaditylinositol (PI), phosphaditylserine (PS) and lysophosphatidylethanolamine, 10–100 μg of phosphatidic acid (PA) and 10–250 μg of phosphatidylcholine (PC) by high-performance liquid chromatography analyses with an evaporative light scattering detector, a Zorbax 7-μm silica column and gradient elution with two solvents. One solvent (A) contained 415 mL isooctane (IOCT), 5 mL tetrahydrofuran (THF), 446 mL isopropanol (IPA), 104 mL CHCl₃ and 30 mL H₂O; and the other solvent (B) contained 216 mL IOCT, 4 mL THF, 546 mL IPA, 154 mL CHCl₃ and 80 mL H₂O. The gradient in which 100% A linearly changed to 100% B in 20 min followed by 12 min of 100% B and then a linear change to 100% A during 5 min separated PE, PS and PC in soybean lecithins and beef lipids, but failed to resolve PI and PA. In these same samples, less polar lipids were separated from phospholipids (PL) by elution from Bond-Elut silica columns with diethyl ether/hexane (20:80, vol/vol), and PL were recovered by elution with methanol. This procedure is useful for concentration of minor lipid components. Levels of PE, PI-PA, PS and PC were higher in granular than in liquid lecithin, and PC was the most abundant PL in soybean lecithins and beef lipids.     

The free radical oxidation of polyunsaturated lecithins

Two unsymmetric polyunsaturated lecithins were allowed to air oxidize and the primary products of autoxidation were isolated and characterized. 1-Palmitic-2-linoleic-phosphatidylcholine undergoes significant oxidation after 16 hr at room temperature under air. A new phospholipid product may be isolated by reverse phase high pressure liquid chromatography (HPLC) and this HPLC fraction is shown to be made up of lipid hydroperoxides formed by free radical oxidation of the homoconjugated diene of the linoleate component of the lecithin. 1-Stearic-2-arachidonic-phosphatidylcholine undergoes a similar oxidation with the arachidonate polyunsaturated functionality being oxidized. The structure of the oxidation products was established by reduction of hydroperoxide with triphenylphosphine, snake venom hydrolysis of the C-2 ester, and HPLC analysis of the resulting hydroxy fatty acids or their methyl esters.     

On the thermal conductivity of granular materials

Stationary heat transfer in a granular material consisting of a continuous medium containing spherical granules of other substances is considered under the assumption that the spatial distribution of granules is random. The effective thermal conductivity characterizing macroscopic heat transfer in such a material is expressed as a certain function of the conductivities and volume fractions of the medium and dispersed substances.For reasons of mathematical analogy all the results obtained for the thermal conductivity are valid while computing the effective diffusivity of some admixture in granular materials as well as for evaluation of the effective electric conductivity or the mean dielectric and magnetic permeabilities of granular conductors and dielectrics.     

Effect of degumming reagents on the recovery and nature of lecithins from crude canola,soybean and sunflower oils

Six reagents (water, citric acid, phosphoric acid, oxalic acid, acetic anhydride and maleic anhydride) were evaluated for their effectiveness in degumming three crude vegetable oils (canola, soybean and sunflower). All chemical reagents tested were found to be significantly more effective than water in removing lecithin material from all three oils except for acetic anhydride degumming of canola. Citric and phosphoric acids were found to be very effective in reducing phosphorus levels in canola oil (91 and 93% removal, respectively). For soybean oil, all reagents except water showed excellent degumming ability by removing 98% phosphorus, while in the case of sunflower oil, maleic anhydride and oxalic acid produced the highest level of phosphorus removal (95 and 90%, respectively). Both citric acid and acetic anhydride were effective in removing Fe from all three oils during degumming (84 to 94%), while phosphoric acid showed slightly lower values (73 to 87%). No significant changes in the phospholipid composition or fatty acid profiles of the phospholipid classes were observed as a result of degumming with the various chemical reagents. In general, canola phospholipids were lowest in palmitic, stearic and linoleic acid and contained the highest levels of oleic acid when compared to soybean and sunflower phospholipids. Both citric and acetic anhydride were found to influence the removal of an unknown glycolipid significantly. Canola lecithin was shown to contain a greater amount of glycolipids than sunflower and soybean lecithins.     

Kinetics of thermal decomposition of hydromagnesite

The thermal decomposition of hydromagnesite has been studied using thermogravimetric analysis. The experiments were conducted in a nitrogen atmosphere with pellets of hydromagnesite in the temperature range 300 to 550°C, and also with powder samples under non-isothermal conditions at a heating rate of 10°C/min. It is found that the reaction proceeds in two stages: dehydration followed by decomposition. The dehydration reaction is controlled by external mass transfer whilst the decomposition reaction is controlled by both external and internal mass transfer. The activation energy for the dehydration reaction was found to be 2.67 × 10⁷ J/kmol. From the non-isothermal analysis the activation energy for the decomposition of magnesium carbonate was found to be 1.62 × 10⁸ J/kmol.     

The thermal cracking of soybean/canola oils and their methyl esters

Triacyl glycerides (TGs) are naturally occurring oils produced by a significant variety of crops, microorganisms (bacteria and algae), and animals (certain fats). The diversity and prevalence of the sources of these compounds suggest that they may serve as an attractive alternative to crude oil as the feedstock for the production of transportation fuels and certain industrial chemicals — organic compounds with carbon chain lengths in the range of C₇ to C₁₅. In the present study a series of batch thermal cracking reactions was performed using soybean oil and canola oil under reaction conditions leading towards attractive yields of potentially valuable (as fuels and/or chemicals) shorter chain products. An attractive yield of alkanes and fatty acids (from oil cracking) or esters (from biodiesel) was obtained. From a parametric study reaction temperature, followed by residence time, was found to have the most significant effect. Significantly, cracking under increased pressures in a hydrogen atmosphere did not improve the yields of desirable species.