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101.
102.
James?A.?KenarEmail author Gerhard?Knothe Robert?O.?Dunn Thomas?W.?RyanIII Andrew?Matheaus 《Journal of the American Oil Chemists' Society》2005,82(3):201-205
Carbonates are a class of compounds that have recently found increasing interest in commercial applications owing to their
physical properties and relatively straightforward synthesis. In this work, physical and fuel properties of five straight-chain
C17–39 and three branched C17–33 oleochemical carbonates were investigated. These properties included cetane number (CN), low-temperature properties, (kinematic)
viscosity, lubricity, and surface tension. The carbonates studied had CN ranging from 47 to 107 depending on carbon chain
length and branching. For the same number of carbons, the CN of carbonates were lower than those of FA alkyl esters owing
to interruption of the CH2 chain by the carbonate moiety. Kinematic viscosities at 40°C ranged from 4.9 to 22.6 mm2/s whereas m.p. ranged from +3 to below −50°C depending on the carbonate structure. High-frequency reciprocating rig testing
showed the neat carbonates to have acceptable lubricity that improved as chain length increased. Finally, the carbonate's
ability to influence cold-flow properties in biodiesel (methyl soyate) and lubricity in low-lubricity ultra-low sulfur diesel
were examined. The carbonates studied did not significantly affect cold flow or lubricity properties at concentrations up
to 10,000 ppm (1 wt%). The properties of the carbonates resemble those of fatty alkyl esters with similar trends resulting
from compound structure. 相似文献
103.
Further compositional analyses of flax: Mucilage,trypsin inhibitors and hydrocyanic acid 总被引:2,自引:0,他引:2
R. S. Bhatty 《Journal of the American Oil Chemists' Society》1993,70(9):899-904
Registered Canadian cultivars of flax, and laboratory-prepared and commercially obtained samples of linseed meal (LM), were
used to determine extract viscosity and mucilage, trypsin inhibitors and hydrocyanic acid (HCN) concentrations. The mucilage
readily leached out from the seed coat (hull) fragments soaked in water, leaving behind pentagon-shaped cells that could be
seen clearly in scanning electron micrographs. Extract viscosity significantly varied in the laboratory-prepared (23–48 cS)
and commercially obtained (30–68 cS) samples of LM and may be used to obtain an indirect, qualitative estimate of flax mucilage.
Mucilage was extracted from whole seed in 5.0–5.3% yields and contained 20–24% protein (about 10% ash and 30% total carbohydrates).
Laboratory-prepared LM (raw) contained 42–51 units of trypsin inhibitor activity, commercially obtained samples, 14–37 units,
and raw rapeseed and soybean meals, 99 and 1650 units, respectively. Picric acid tests (qualitative) showed only traces of
HCN in ten cultivars of freshly ground flax. The acid silver nitrate titration procedure measured HCN quantitatively, but
showed its presence only in three of the five cultivars investigated. HCN was conveniently measured by a colorimetric procedure
(barbituric acidpyridine reaction), which may be used to screen flax cultivars. HCN content of flax was significantly influenced
by environments (growth location and season) and, to a less extent, by cultivar. 相似文献
104.
Long-term performance of cement paste during combined calcium leaching-sulfate attack: kinetics and size effect 总被引:1,自引:0,他引:1
This paper presents experimental results obtained on cement paste samples (water/cement ratio of 0.4) subjected to a low-concentration (15 mmol/l) external sulfate attack during several weeks. Chemical and microstructural analyses include the continuous monitoring of calcium loss and sulfate consumption within the cement paste, periodic layer by layer X-ray diffraction (XRD)/energy-dispersive spectrometer (EDS) analyses of the solid constituents of the cement matrix (ettringite, portlandite, gypsum) within the calcium-depleted part of the samples. Scanning electron microscopy (SEM) and visual observations are used to follow the crack pattern evolution during the external sulfate attack. The relation between the size of the specimen and crack initiation/development is investigated experimentally by performing tests on samples with different thickness/diameter ratios. 相似文献
105.
Internal relative humidity distribution in high-performance cement paste due to moisture diffusion and self-desiccation 总被引:1,自引:0,他引:1
This investigation was carried out to study internal relative humidity (IRH) distribution of cement paste made with different water / cement ratios (w / c) and mineral admixtures in isothermal drying conditions. IRH changes in cement paste resulting from self-desiccation and moisture diffusion, respectively, at different ages were studied. The change laws of IRH in cement paste resulting from combining moisture diffusion with self-desiccation were discussed. The results indicate that IRH reduction of cement paste with w / c higher than 0.4 is mainly affected by moisture diffusion. However, IRH reduction of cement paste with w / c no higher than 0.4 is controlled by both moisture diffusion and self-desiccation. With the decrease of w / c, IRH reduction of cement paste resulting from self-desiccation increases, and IRH reduction resulting from moisture diffusion decreases at a given age. IRH decrement of cement paste incorporated with silica fume and ground blast-furnace slag is higher than that of control paste. w / c and the distance to the exposed surface play a significant role in IRH change resulting from moisture diffusion in isothermal drying condition. Change laws of IRH in cement paste with silica fume due to moisture diffusion considering self-desiccation are different from those in cement paste without silica fume. 相似文献
106.
对超声波进行了简单的介绍,对其在聚合物成型加工中的降粘机理进行了一定的研究以及对它在聚合物成型加工中的应用进行了综述。在聚合物的成型加工中,超声波的合理施加可以大幅度的降低聚合物熔体的粘度,降低加工设备的要求和条件,更有利于高粘度聚合物的成型加工。 相似文献
107.
108.
讨论了熔体粘度波动时熔体的可纺性、POY的物性指标及后加工性能、DTY的质量指标及其染色等情况。结果表明;熔体粘度偏低时,前纺飘丝断头增多,后纺伸头困难,POY和DTY的强度降低、伸长度增大,DTY有较多的点状僵丝,袜带吸色较深且有较多的色斑点;熔体粘度偏高时,熔体泵前压力偏低,后加工张力高,纸筒管易于破裂。POY和DTY纤度偏小,强度增大,伸长度减小,各种不匀增大,袜带吸色较浅且较为均匀。初步确定熔体粘度的波动范围应控制在1.615—1.650. 相似文献
109.
The viscosity of polyacrylamide (PAM) dilute aqueous solutions with NaCl, glucose, and SDS as additives was measured by Ubbelohde viscometry. There was linear relationship between reduced viscosity vs. PAM concentration in aqueous solutions. The Huggins constant k and intrinsic viscosity [η] were used to study the conformation of the polymer chains and the degree of polymer–solvent interaction. In addition, the viscosity of diluted PAM solutions in water with acetone, ethanol, DMF, and ethylene glycol as cosolvent was measured. It was found that the polymer chain conformation contracted as the acetone, ethanol, and DMF cosolvent composition ratio increased, but there was no distinguishing difference between water–ethylene glycol compositions. The solution properties of PAM were used to estimate the swelling properties of PAM gel in the same external conditions, as gel is formed by crosslinking of linear polymer. In good solvent the polymer chain should be expanded, and gel is expected to have large swelling ratio. In water cosolvent systems, when the linear polymer chain underwent coil–globule transition, PAM gel should have volume phase transition under corresponding external conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3122–3129, 2003 相似文献
110.
Heavy-oil-in-water (o/w) emulsions containing produced sand were prepared using commercially available emulsifiers. The emulsions were tested in beakers for emulsion type, quality, and sand-retention characteristics. The apparent viscosities of the o/w emulsions were measured. The effects of polymer addition on the apparent viscosity and sand-carrying capability of the emulsions were also studied. The results of the breaker tests indicate that most emulsifier solutions water-wet the beaker wall and temporarily improve heavy-oil flow characteristics. However, most of the chemicals also water-wet the sand particles and cause sand dropout. The Flothin F2 chemical alone showed stable oil dispersion and, in combination with the Flocon 4800C polymer, showed very good sand-retention, viscosity-reduction, and stable oil-dispersion characteristics. 相似文献