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111.
112.
Kinematic viscosity of biodiesel components (fatty acid alkyl esters) and related compounds at low temperatures 总被引:1,自引:0,他引:1
Biodiesel, defined as the mono-alkyl esters of vegetable oils and animal fats is, has undergone rapid development and acceptance as an alternative diesel fuel. Kinematic viscosity is one of the fuel properties specified in biodiesel standards, with 40 °C being the temperature at which this property is to be determined and ranges of acceptable kinematic viscosity given. While data on kinematic viscosity of biodiesel and related materials at higher temperatures are available in the literature, this work reports on the kinematic viscosity of biodiesel and a variety of fatty acid alkyl esters at temperatures from 40 °C down to −10 °C in increments of 5 °C using the appropriately modified standard reference method ASTM D445. Investigating the low-temperature properties of biodiesel, including viscosity, of biodiesel and its components is important because of the problems associated with the use of biodiesel under these conditions. Such data may aid in developing biodiesel fuels optimized for fatty ester composition. An index termed here the low-temperature viscosity ratio (LTVR) using data at 0 °C and 40 °C (divide viscosity value at 0 °C by viscosity value at 40 °C) was used to evaluate individual compounds but also mixtures by their low-temperature viscosity behavior. Compounds tested included a variety of saturated, monounsaturated, diunsaturated and triunsaturated fatty esters, methyl ricinoleate, in which the OH group leads to a significant increase in viscosity as well as triolein, as well as some fatty alcohols and alkanes. Esters of oleic acid have the highest viscosity of all biodiesel components that are liquids at low temperatures. The behavior of blends of biodiesel and some fatty esters with a low-sulfur diesel fuel was also investigated. 相似文献
113.
114.
The intrinsic viscosities of eleven narrow molecular weight distribution polystyrene samples ranging from number-average molecular weight 1820 to 1 292 000 have been determined in pure solvents of tetrahydrofuran and chloroform with a Ubbelohde No. 1 viscometer at 25°C. By combining the original and modified Fox-Flory viscosity treatments, respectively, with the Flory-Huggins Lattice theory, the interaction parameters were calculated. With the aid of original and modified UNIFAC methods the solvent activity, clustering function of the solvent, and the interaction parameter were computed and compared with the experimental data. It was established that the influence imposed by the polymer molecular weight on the activity of the solvent, the clustering function of solvent, and interaction parameter is insignificant. The modified UNIFAC method satisfactorily predicted the solvent activity as illustrated by previous investigators. However, both UNIFAC methods failed to predict the interaction parameter. 相似文献
115.
A fumed hydrophilic nano‐silica‐filled polypropylene (PP) composite was blended with a liquid‐crystalline polymer (LCP; Rodrun LC5000). The preblended polymer blend was extruded through a capillary die; this was followed by a series of rheological and morphological characterizations. The viscosity of the PP matrix increased with the addition of the hydrophilic nano‐silica. At shear rates between 50 and 200 s?1, the composite displays marked shear‐thinning characteristics. However, the incorporation of LC5000 in the PP composite eliminated the shear‐thinning characteristic, which suggests that LC5000 destroyed the agglomerated nano‐silica network in the PP matrix. Although the viscosity ratio of LCP/PP was reduced after the addition of nano‐silica fillers, the LCP phases existed as droplets and ellipsoids. The nano‐silicas were concentrated in the LC5000 phase, which hindered the formation of LCP fibers when processed at high shear deformation. We carried out surface modification of the hydrophilic nano‐silica to investigate the effect of modified nano‐silica (M‐silica) on the morphology of the PP/LC5000 blend system. Ethanol was successfully grafted onto the nano‐silica surface with a controlled grafting ratio. The viscosity was reduced for PP filled with ethanol‐M‐silica when compared to the system filled with untreated hydrophilic nano‐silica. The LC5000 in the (PP/M‐silica)/LC5000 blend existed mainly in the form of fibrils. At high shear rates (e.g., 3000 s?1), the LC5000 fibril network was formed at the skin region of the extrudates. The exclusion of nano‐silica in the LC5000 phase and the increased viscosity of the matrix were responsible for the morphological changes of the LCP phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1484–1492, 2003 相似文献
116.
Polyolefins (PO) were melt mixed with thermoplastic polyurethane (TPU) in a 20 : 80 weight ratio with or without compatibilizer containing 0.5 wt % of maleic anhydride. Effects of component viscosities on morphology and on mechanical properties of the blend were studied by scanning electron microscope (SEM), tensile property analysis, and dynamic mechanical analysis (DMA). It was found that the disperse particle size of compatibilizer‐free blends decreased with the decreasing viscosity ratio of the disperse phase to TPU. The efficiency of the compatibilizer in reducing the particle size varied with viscosity ratios of the disperse phase to compatibilizer. However, the particle size did not decrease with the decreasing viscosity ratio monotonically. With lower viscosity ratio, addition of 5 wt % compatibilizer resulted in a greater reduction of particle size and less loss in the tensile properties as compared to the TPU matrix. For the polyethene (PE) that has the lowest viscosity value among all the POs, its size in the blend was stabilized with the addition of compatibilizer and no compatibilization was detected by DMA and by tensile property analysis. The mobility of the disperse phase and compatibilizer and the dispersion competition between them seemed important. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 875–883, 2006 相似文献
117.
电场作用下水的粘性试验分析 总被引:2,自引:2,他引:0
丁凯 《河北工程大学学报(自然科学版)》2010,27(3):14-17
电场作用下极性水分子和离子水化物将有序排列,由此导致水的粘度特性显著变化。文中通过室内试验,研究垂直于水流方向施加的电场对水的粘度特性的影响,在数字直流电源产生的强电场中进行常水头渗流试验,获得了水的粘度与电场强度关系的试验曲线,并观察在电场作用下,水的粘度与所含离子浓度、渗流速度等因素的关系,基于试验结果分析了电场改变水的粘度特性的作用机制。试验结果表明,外加电场对水的粘度有明显的影响,随着电场强度增加,水的粘度呈减小的趋势;在相同的电场强度下,水的粘度与离子浓度成正比关系,与渗流速度成反比关系。 相似文献
118.
为了获得适合纯钨注射成形的黏结剂,通过热力学计算和喂料的流变实验,系统地研究了黏结剂组元的相容性和不同配方的蜡基黏结剂的流变性能,分析了多种因素对喂料黏度的影响,综合评价了不同黏结剂构成的喂料的流变性能,并对喂料进行了SEM观察,结果表明:所选用的黏结剂体系中各组元之间有很好的相容性,当PW与其他组元的质量比大于4时,表现为热力学相容性;由60%PW-10%HDPE-12%PS-13%PP-5%SA组成的黏结剂的流变性能最好,其综合模塑性指数为7.07 m2/N.s.K,SEM结果显示其喂料相当均匀. 相似文献
119.
复方丹参滴丸是治疗冠心病等疾病的纯中药固体制剂.在滴丸滴制时,滴丸的动力黏度影响滴丸成品的外观质量,如圆整度、硬度、大小和干裂度等.本文研究复方丹参滴丸制剂的含水率和溶化温度对滴丸动力黏度的影响.通过实验测定和数据分析得出,滴丸制剂的溶化温度在75℃~85℃,滴丸制剂含水率为6%~10%的条件下,滴丸的动力黏度值基本恒定,滴丸的滴制效果最佳.实验结果已经用于制订新的生产工艺,指导实际药品的生产. 相似文献
120.
通过对脱硅过程中含硅铝酸钠溶液表面张力和黏度的测定,研究脱硅温度、氧化铝浓度、苛性比等因素对溶液的表面张力和黏度的影响.实验结果表明:低温、高浓度、高苛性比的溶液表面张力和黏度较大,反之则较小.通过XRD检测手段对脱硅后的渣相进行分析,用衍射峰与结构的关系解释溶液的表面张力和黏度的变化对硅量指数的影响. 相似文献