润滑油粘度指标分析

粘度是润滑油的一个重要指标,对润滑油的使用和研究有重要作用。本文总结了粘度的评价方法,分析了基础油组成、温度、压力、添加剂以及剪切力对润滑油粘度的影响,研究了粘度与润滑油润滑性、流动性以及抗泡性的关系,为润滑油的选用和研究提供参考依据。     

中粘度PAO的合成

聚α-烯烃合成润滑油(PAO)是重要的合成润滑油之一。使用氯化铝-环己醇络合催化剂,对1-癸烯齐聚反应进行了研究,合成了不同粘度级别的中粘度PAO。考察了n(AlCl3)∶n(1-癸烯)、n(环己醇)∶n(AlCl3)、反应温度、反应时间、烯烃原料对PAO收率和性能的影响。实验结果表明:采用氯化铝-环己醇络合催化剂,以1-癸烯为原料,n(AlCl3)∶n(1-癸烯)=5∶100,反应时间4 h以上的条件下,在0.1~0.7范围内调整n(环己醇)∶n(AlCl3)或在20~80℃范围内改变反应温度,可以合成不同粘度级别的中粘度PAO。在上述条件下,PAO100℃运动粘度随n(环己醇)∶n(AlCl3)的增加而增大,随反应温度的升高而减小;PAO收率在85%以上,具有低凝点、高粘度指数的显著特点,是高质量的聚α-烯烃合成润滑油。     

金溪膨润土的流变性研究

对金溪膨润土的流变性进行了系统研究。结果表明:质量分数、剪切力、溶解温度、加热时间、pH值、冻融条件与时间等变化对金溪膨润土的粘度有较大影响。金溪膨润土溶液具有较高的粘度,当矿浆质量分数达到60%时,其粘度为542.8mPa·s,金溪膨润土溶液为"非牛顿流体",加热时间与温度对金溪膨润土粘度影响较大,金溪膨润土溶液在酸性和碱性条件下都较为稳定,冻融处理后金溪膨润土粘度大幅度下降。     

一种测定尼龙-11特性粘度的方法

在采用稀释作图外推法测定尼龙 - 11特性粘度的大量实验基础上 ,研究确定了用乌氏粘度计单点法测定尼龙 - 11特性粘度经验公式中的经验常数 ,通过与稀释法的比较 ,检验其准确度和精确度。结果表明 ,误差小于± 0 5%的单点法可用于测定尼龙 -11的特性粘度     

温度及剪切速率对延长原油粘度的影响规律研究

延长原油为高含蜡原油,原油中石蜡在输送过程中受温度及剪切力的影响较大。因此,采用流变学测试与分析方法对温度及剪切速率对粘度的影响规律进行了研究。研究结果表明：延长原油的凝点为26℃,粘度在温度由28℃降至23℃时由96mPa·s激增至192mPa·s,提高剪切速率可较大幅度的降低原油粘度但增加到100S^-1后对粘度的影响趋于稳定。     

高粘度指数α-烯烃合成油的制备

以三氯化铝为催化剂,高纯度低碳α-烯烃为原料合成了α-烯烃合成油。考查了反应温度、催化剂用量以及反应压力对产品收率及性质的影响。得到了最佳的反应条件:反应温度为100℃、催化剂用量为5%(质量分数,原料烯烃)、反应压力为0.6~0.8MPa。合成油产品粘度指数为131、凝点-48℃、闪点285℃、燃点293℃。     

航空润滑油运动黏度影响因素分析

润滑油是保证航空发动机正常工作的重要材料,是现代航空油料的重要组成,而油品的润滑性能的好坏又直接取决于油品黏度指标与其衰变。文章从基础油结构、抗氧剂组成等内因和温度、压力等外因分析了航空润滑油黏度的变化,重点讨论了聚α-烯烃(PAO)航空润滑油基础油分子结构与油品黏度之间的关系,概述了抗氧剂对油品性能影响的研究现状,分别从温度、压力和剪切力等三方面系统概述航空润滑油工况环境对油品黏度指标的影响。     

润滑油运动粘度测定结果不确定度的评定

由于润滑油产品中的运动粘度指标对各类滴水润滑油的分类起着决定作用,科学准确地获得润滑油的运动枯度测量结果,以便用户正确选择合适品种的润滑或参与国际贸易检测结果的比较,我们依据JJF-1059—1999《测定不确定度评定与表示》及GB/T265-1988《石油产品运动粘度测定法和运动粘度计量法》,按经验方法的评定程序,分析了润滑油运动粘度测量结果不确定度的来源,建立了相应的数学模型,利用标准物质对不确定度的分量进行评估,获得润滑油在100℃时运动粘度的扩展不确定度：U=0．54％．     

纺丝箱体温度及计量泵温度与聚酯粘度降关系的探讨

在一定的工艺条件下，定性指出了纺丝箱体温度、计量泵温度与粘度降成正比。通过数理统计的回归分析法。找出了两条经验公式。     

1,6-二磷酸果糖溶液基本性质

研究了 1 ,6-二磷酸果糖溶液在不同酒精浓度和 p H下的溶解度以及不同 1 ,6-二磷酸果糖溶液的浓度、温度及 p H下的粘度 ,并给出了浓度对粘度的关联式。实验发现 ,溶液的温度和 p H对溶液的粘度有很大的影响 ,因此升高溶液的温度和降低溶液的 p H有利于改善溶液的传质状况和结晶条件 ,为 1 ,6-二磷酸果糖的结晶新体系的研究提供依据。     

PMMA熔体黏度影响因素实验研究

针对不同类型的聚甲基丙烯酸甲酯(PMMA)材料熔体的黏度开展实验研究。结果表明,3种不同的PMMA材料因相对分子质量大小的不同而使其流变特性存在一定的差异,在相同的温度下和压力下,相对分子质量越大,剪切黏度越大。随着挤出压力的增加,剪切速率则增加,剪切黏度减小,呈现剪切变稀的特征。同时剪切黏度随温度的变化也较为显著,随着温度的增加,剪切黏度变小,当温度达到280 ℃,3种材料的剪切黏度逐渐变得相等。     

Geometrical dependence of viscosity of polymethylmethacrylate melt in capillary flow

The shear viscosity of polymethylmethacrylate (PMMA) melt is particularly investigated by using a twin‐bore capillary rheometer at four temperatures of 210, 225, 240, and 255°C with different capillary dies. Experimental results show that the geometrical dependence of shear viscosity is significantly dependent on melt pressure as well as melt temperature. The measured shear viscosity increases with the decrease of die diameter at lower temperatures (210 and 225°C) but decreases with the decrease of die diameter at higher temperatures (240 and 255°C). Based on the deviation of shear viscosity curves and Mooney method, negative slip velocity is obtained at low temperatures and positive slip velocity is obtained at high temperatures, respectively. Geometrical dependence and pressure sensitivity of shear viscosity as well as temperature effect are emphasized for this viscosity deviation. Moreover, shear viscosity curve at 210°C deviates from the power law model above a critical pressure and then becomes less thinning. Mechanisms of the negative slip velocity at low temperatures are explored through Doolittle viscosity model and Barus equation, in which the pressure drop is used to obtain the pressure coefficient by curve fitting. Dependence of pressure coefficient on melt temperature suggests that the pressure sensitivity of shear viscosity is significantly affected by temperature. Geometrical dependence of shear viscosity can be somewhat weakened by increasing melt temperature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3384–3394, 2013     

高填充固体推进剂模拟物加工流变行为的实验研究

针对高填充固体推进剂模拟物,围绕其在稳态剪切及动态剪切模式下的流变特性,分别采用出口增压式毛细管流变仪及旋转流变仪,在100~120 ℃及50~100 ℃下考察了压力与剪切振荡幅度对物料剪切黏度（η）的影响,计算了熔体压力对η的敏感性参数并提出了针对该类物料真实η的有效修正方法及低剪切法向力下的测试方法。稳态剪切测试结果表明,熔体压力介于12~121 MPa之间时,其压力敏感性参数介于4.81~9.65 GPa^-1发生变化,相同温度及剪切速率下熔体η随压力表现出幂指数的递增变化规律;动态剪切测试表明,即使在不高于50 N的熔体剪切法向力作用下（法向力15~42 N）,高填充模拟物η在0.01~100 s^-1内也会表现出大约2倍的差异;对于表现出强类固体特征的高填充模拟物复杂体系,动态剪切测试中的剪切应变振幅对η的测试结果影响明显,尤其在低温大振幅剪切情况下,高填充物料与剪切平板之间还易发生“打滑”。     

稠油包水乳状液的表观黏度

以渤海SZ36-1稠油、矿化水为工质配制了2组不同液滴直径的W/O型乳状液,研究了温度、含水率、剪切率和液滴直径对乳状液黏度的影响。结果表明,温度对乳状液表观黏度的影响非常明显,而对相对黏度的影响却较小;同时含水率、剪切率和液滴直径也是影响乳状液黏度的重要因素,低含水率下,剪切率、液滴直径对黏度的影响不明显,而当含水率较高时,剪切率、液滴直径的影响非常突出,乳状液呈现出强烈的剪切稀释特性。利用国内外现有的一些黏度模型对实验获得的黏度数据进行了预测分析,发现Brinkman(1952)模型具有较好的预测精度。     

Shear viscosity,extensional viscosity,and die swell of polypropylene in capillary flow with pressure dependency

The shear and extensional viscosities of a polypropylene resin were studied using a capillary rheometer and capillary dies of 1‐mm diameter and length of 10, 20, and 30 mm. Melt temperatures at 190, 205, and 220°C and shear rates between 100 and 5000 s^?1 were used. At the highest shear rate a visible melt fracture was observed. An equation relating the pressure drop and die length was derived with consideration of pressure effects on melt viscosities and the end effect. After the correction for pressure effects the true wall shear stress and end effect at zero pressure were calculated. The end effect showed a critical stress of melt fracture around 10⁵ Pa, and increased rapidly when shear stress increased above the critical stress. From shear stress the shear viscosity was calculated, and a power law behavior was observed. Extensional viscosity was calculated from the end effect and showed a decreasing trend when strain rate increased. After time–temperature superposition shift shear viscosity data correlated well, but an upward trend was observed in extensional viscosity when melt fracture occurred. Die swell ratio at different temperatures can be plotted as a function of wall shear stress and was higher for shorter dies. © 2002 Wiley Perioodicals, Inc. J Appl Polym Sci 84: 1269–1276, 2002; DOI 10.1002/app.10466     

Melt fracture,melt viscosities,and die swell of polypropylene resin in capillary flow

The melt fracture, shear viscosity, extensional viscosity, and die swell of a polypropylene resin were studied using a capillary rheometer and dies with a 0.05‐cm diameter and length/radius ratios of 10, 40, and 60. A temperature of 190°C and shear rates between 1 and 5000 s^?1 were used. A modified Bagley plot was used with consideration of pressure effects on both the melt viscosity and end effect. The shear viscosity was calculated from the true wall shear stress. When the true wall shear stress increased, the end effect increased and showed critical stresses at around 0.1 and 0.17 MPa. The extensional viscosity was calculated from the end effect and it showed a decreasing trend when the strain rate increased. Both the shear and extensional viscosities correlated well with another polypropylene reported previously. The die swell was higher for shorter dies and increased when shear stress increased. When the shear rates increased, the extrudate changed from smooth to gross melt fracture with regular patterns (spurt) and then turned into an irregular shape. In the regular stage the wavelength of the extrudates increased when the shear rate increased. The frequency of melt fracture was almost independent of the shear rate, but it decreased slightly when the die length increased. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1587–1594, 2003     

Rheological properties of poly(trimethylene terephthalate) in capillary flow

The shear viscosity, extensional viscosity, and die swell of the PTT melt were investigated using a capillary rheometer. The results showed that the PTT melt was a typical pseudoplastic fluid exhibiting shear thinning and extensional thinning phenomena in capillary flow. There existed no melt fracture phenomenon in the PTT melt through a capillary die even though the shear rate was 20,000 s^?1. Increasing the shear rate would decrease the flow activation energy and decline the sensitivity of the shear viscosity to the melt temperature. The molecular weight had a significant influence on the flow curve. The flow behavior of the PTT melt approached that of Newtonian fluid even though the weight‐molecular weight was below 43,000 s^?1 at 260°C. The extensional viscosity decreased with the increase of the extensional stress, which became more obvious with increasing the molecular weight. The sensitiveness of the extensional viscosity to the melt temperature decreased promptly along with increasing the extensional strain rate. The die swell ratio and end effect would increase along with increasing the shear rate and with decreasing the temperature, which represented that the increase of the shear rate and the decrease of temperature would increase the extruding elasticity of the PTT melt in the capillary die. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 705–709, 2005     

纳米流体黏度特性

引言纳米流体是将纳米粒子添加到基液中形成的稳定悬浮混合液。近10年来,国内外许多学者对纳米流体的导热性能进行了大量研究,添加纳米粒子后溶液的导热能力明显加强。Jung等[1]对微渠道中的纳米流体对流传热特性进行了研究,研究发现粒径为170nm、体积分数为1.8%的Al2O3-水纳     

氯磺化聚乙烯流变性能研究

研究氯磺化聚乙烯(CSM)的流变性能，特别是剪切速率、剪切应力和温度对CSM熔体表观粘度的影响。试验结果表明，CSM熔体在试验温度范围内为假塑性流体，随温度的升高其非牛顿性减弱；CSM熔体的表观粘度随表观剪切速率和剪切应力的增大以及温度的升高而降低；剪切应力对CSM的粘流活化能影响不大。     

Observation of melt fracture of polypropylene resins in capillary flow

Melt fracture, shear viscosity, extensional viscosity, and die swell of two polypropylene resins were studied using a capillary rheometer. A modified Bagley plot with consideration of pressure effects on melt viscosity and end effect was used. From the true wall shear stress the shear viscosity was calculated. Extensional viscosity was calculated from the end effect. Both shear and extensional viscosities of different molecular weights and temperatures correlated well under the time-temperature Williams-Landel-Ferry (WLF) superposition. Die swell increased when shear stress increased, and was higher for shorter dies at a given shear rate. When shear rates increased the extrudate staged from smooth to gross melt fracture with regular patterns (spurt), and then turned into irregular shapes. In the regular stage the wavelength of extrudates was measured, and corresponding frequency was calculated. The frequency increased when molecular weight decreased and when melt temperature increased. The shift factor based on shear viscosity also brought frequency data of different molecular weights and temperatures into master curves. The frequency decreased slightly when die lengths increased from L/R=10 to 60. A small maximum was observed when shear rates increased.