面向吞咽障碍的大豆蛋白增稠剂润滑特性研究

为探究大豆蛋白作为面向吞咽障碍患者的食品增稠剂可行性,基于流变学及摩擦学的评定方法,采用MCR301流变仪测试不同质量分数大豆蛋白溶液的流变特性,在MFT-5000磨损试验机上开展软摩擦条件下不同滑动速率时大豆蛋白润滑特性研究,并与常见的淀粉类、黄原胶类增稠剂的特性进行比较。结果表明：大豆蛋白溶液表现出弱凝胶的性质,其溶液黏度随着大豆蛋白质量分数的增加而增大,且经人工唾液稀释后溶液仍保持较高的黏度;在口腔软摩擦的环境下大豆蛋白溶液表现出较好的润滑特性,其摩擦因数随着大豆蛋白质量分数的增加而有所降低;与淀粉类及黄原胶类增稠剂相比,大豆蛋白溶液具有更低的摩擦因数,其研究结果为吞咽障碍的功能食品开发提供了参考。     

高效液相色谱荧光检测法测定植物性食品中阿维菌素类药物

建立了植物性食品中阿维菌素类药物(阿维菌素、伊维菌素、多拉菌素、甲氨基阿维菌素苯甲酸盐和乙酰胺基阿维菌素)残留量的高效液相色谱测定方法。用乙腈提取溶剂样品中的目标物,碱性氧化铝固相萃取小柱和炭黑氨基柱净化,经N-甲基咪唑和三氟乙酸酐衍生化后,用高效液相色谱-荧光检测器在激发波长为365nm,发射波长为475nm处测定。在添加浓度4.0～100μg/kg范围内,平均添加回收率在78.5%～99.2%之间,相对标准偏差在0.56%～7.25%之间,检出限为1.0μg/kg。方法简便、快速、准确。在0.004mg/L～2.0mg/L范围内,阿维菌素类药物标准工作溶液的色谱峰面积与质量浓度成良好的线形关系,相关系数为0.9995。     

用旋转粘度计法研究非牛顿流体的流变性能

本文主要介绍在5个不同减阻剂浓度(0 mg/L,100 mg/L,200 mg/L,300 mg/L,400 mg/L)和不同温度(15℃,20℃,25℃)下,用旋转粘度计法测定减阻剂样品在7m in内,剪切速率从0~183.45/s下,研究0号柴油及加入减阻剂后的流变性能。一般情况下,幂律模型适合于大部分非牛顿流体。加剂后的柴油溶液,与空白柴油相比较,稠度都有不同程度的提高。在低剪切速率下,大多数实验结果表现为牛顿流体流变行为,但D-41(块)溶液例外,浓度为300mg/L的15℃和20℃及浓度为400mg/L的25℃表现出假塑性流动行为。浓度与粘度的线性关系用关系和指数关系相对于乘幂关系拟合程度较高,而用乘幂关系拟合程度较低。粘度与温度间服从于阿累尼乌斯方程。     

基于超分子溶剂分散液液微萃取技术测定食品接触材料中8种邻苯二甲酸酯的迁移量

建立了食品接触材料中8种邻苯二甲酸酯类增塑剂迁移量的同位素稀释超高效液相色谱-串联质谱测定方法。以正辛醇、四氢呋喃和水形成的超分子溶剂为萃取剂,对食品接触材料迁移溶液中的邻苯二甲酸酯类增塑剂进行分散液液微萃取。分别考察了烷基醇的种类与用量、四氢呋喃用量、涡旋时间等因素对萃取效率的影响。采用Waters Acquity UPLC BEH C18色谱柱（2.1 mm×50 mm×1.7 μm）,以甲醇 水为流动相进行梯度洗脱,在电喷雾正离子模式下,采用多反应监测模式进行定性及定量分析。结果表明,8种邻苯二甲酸酯在各自的浓度范围内线性关系良好,线性相关系数r²＞0.99,检出限为0.1~1.0 μg/L,定量限为0.5~2.0 μg/L。在低、中、高3个添加水平下,8种邻苯二甲酸酯类增塑剂的平均回收率为84.8%~117.5%,相对标准偏差为2.1%~18.7%（n=6）。该方法准确可靠、操作简便,适用于食品接触材料中邻苯二甲酸酯类增塑剂迁移量的检测。     

液相色谱-原子荧光法测定化妆品中硫柳汞和苯基汞

建立了液相色谱(HPLC)-原子荧光(AFS)联用法测定化妆品中硫柳汞和苯基汞含量的方法。样品经超声提取后高速离心,经0.45μm滤膜过滤,HPLC-AFS测定,保留时间定性,外标法定量。该方法硫柳汞在2.5μg/L～50μg/L、苯基汞在62.5μg/L～1250μg/L呈良好的线性关系(R2≥0.998)。在0.075μg、0.15μg、0.225μg 3个添加浓度水平下硫柳汞的回收率为84.7%～101.7%,在1.875μg、3.750μg、5.625μg 3个添加浓度水平下硫柳汞的回收率为84.1%～103.9%,定性重复性为0.30%～0.33%,定量重复性为4.22%～4.96%,硫柳汞的检出限为0.060μg/L,苯基汞的检出限为0.23μg/L(S/N=3)。该方法成本低,分析速度快,精密度好,检出限低,适用于化妆品中硫柳汞和苯基汞的检测。     

自修复材料及其光饰预处理技术对轴承寿命的影响

根据目前轴承行业延寿技术研究的新方向,以6307深沟球轴承为例,采用两种不同的润滑方式,分别对轴承表面未处理与预处理及油脂润滑与油脂中添加自修复材料ART润滑的6组轴承进行寿命对比试验.试验数据表明:润滑剂中添加自修复材料ART并进行光饰预处理技术后,脂润滑及油润滑的L10寿命分别提高了4倍和2倍以上,可靠性分别由77.44%,97.9%增加至99.98%,99.7%.     

高效液相色谱-串联质谱测定奶粉中3种苯并咪唑类药物残留

建立了高效液相色谱-串联质谱测定全脂和脱脂奶粉中奥芬达唑,阿苯达唑和芬苯达唑3种苯并咪唑类杀虫剂残留的方法。通过比较不同溶液的提取效率,最终选择含1%乙酸的甲醇作为提取溶液,正己烷和阳离子固相萃取两步净化,有效去除奶粉基质中的抑制干扰物。以乙腈和含0.5 mmol/L醋酸铵及0.1%甲酸的水溶液为流动相,C₁₈作为分析色谱柱,采用梯度洗脱方式进行液相色谱分离。脱脂奶粉和全脂奶粉3个添加水平的回收率范围为70.0%~85.8%,相对标准偏差均小于7.5%,在2～100 μg/L浓度范围内,线性相关系数大于0.997 3,方法检测限为10 μg/kg,能满足现有各国残留限量要求。     

高分子复合材料水润滑轴承的温升实验研究

对以聚四氟乙烯（PTFE）为基体的高分子复合材料水润滑滑动轴承在不同工况下的温升进行了实验研究。结果表明：供水量对温升的影响最为显著,其次是载荷和供水量。在载荷低于600N,转速低于1400r/min条件下,2.5L/min的供水量已经可以达到较好的润滑冷却效果;载荷对温升的影响规律较为复杂,随着载荷的增加,温升会出现一个极小值;而温升随转速的变化则较为平缓。     

口服液中全氟烷基类化合物的快速测定

建立了高效液相色谱-串联质谱法（HPLC-MS/MS）检测口服液中16种全氟烷基类化合物（PFASs）。样品采用2%盐酸酸化甲醇溶液提取,用NaOH溶液将提取液的pH值调至中性后,加入PSA和GCB粉末吸附剂分散固相萃取富集净化,用50 mmol/L三乙胺-甲醇溶液洗脱,HPLC-MS/MS负离子多反应监测模式测定,同位素内标法定量。结果表明：在0.2~20 μg/L浓度范围内,16种全氟烷基类化合物具有良好的线性关系,线性相关系数（r）大于0.996,方法的检出限均小于0.15 μg/L,定量限均小于0.43 μg/L;在0.5、1.0、2.0和5.0 μg/L添加水平下,化合物的平均回收率在80.8%~119%之间,相对标准偏差均小于10.5%。应用该方法对市场上随机采购的24种口服液样品进行检测,检出了14种PFASs化合物,其中以PFBA、PFOA、PFHxA、PFHpA、PFNA、PFDA最为普遍,最高浓度达5.05 μg/kg。该方法快速、简便、灵敏度高、重现性好,适用于口服液中PFASs的检测。     

类金刚石膜在水环境下的摩擦学行为

测试了 CoCrMo合金表面沉积类金刚石薄膜与CoCrMo在水溶液润滑下的摩擦磨损行为。结果表明：摩擦副在不同浓度牛血清白蛋白溶液润滑下的平均摩擦因数均在0.10左右,CoCrMo合金销磨损量最小值为1.69×10-5 mm3;相同条件下,生理盐水溶液润滑的磨损量为1.38×10-5 mm3,且销表面有转移膜生成;牛血清白蛋白溶液润滑时,界面蛋白吸附层屏蔽了转移膜的形成。根据结果可知,转移膜的形成经历了磨屑附着、连续转移、局部脱落的过程。     

Atomic Force Microscopy and Thermo-Rheological Characterisation of Lubricating Greases

In this work, non-perturbed microstructures of several commercial and model lubricating greases, differing in nature and concentration of the thickener agent, were examined using the atomic force microscopy (AFM) technique. Grease microstructure mainly depends on the nature of the thickener employed and, also, on thickener concentration and viscosity of the base oil. Thermal-induced changes in the viscoelastic response of lubricating greases have been investigated by using different rheological techniques in a temperature range of 0–175 °C. Small-amplitude oscillatory shear (SAOS) measurements were carried out to determine the mechanical spectra of the different samples studied. Lubricating grease rheological thermal susceptibility was analysed by following the evolution of the plateau modulus with temperature. SAOS functions dramatically decrease, in most cases, above a characteristic temperature, which depends on nature and/or concentration of the thickener used and therefore on grease microstructure. The thermo-mechanical reversibility of grease microstructure has been studied by carrying out triple-step-shear stress tests (shear stresses inside and outside of the linear viscoelasticity range), at different temperatures. The degree of lubricating grease non-reversible structural breakdown, which increases with temperature, depends on the shear stress applied above the linear viscoelasticity limits.     

Grease lubrication of rolling element bearings — role of the grease thickener

The contribution of grease thickener to lubricant film formation was examined in this paper. Lubricant film thickness and friction were measured for different grease thickener types in a bearing simulation device. The results showed that the greases formed thick (20–80nm), low friction surface layers at low speeds, which were much greater than the corresponding base oil film. These films appeared to be formed by the physical deposition of thickener in the track during overrolling of the grease. This was confirmed by infrared reflection analysis, which showed the deposited films to have increased thickener content. The ability of grease to form renewable physically deposited solid films has significant implications for optimising lubricant formulation for certain applications, e.g. bearings operating at high temperatures and low speeds where a conventional elastohydrodynamic lubricating film would be inadequate. Copyright © 2007 John Wiley & Sons, Ltd.     

Rheological and Tribological Characterization of a New Acylated Chitosan–Based Biodegradable Lubricating Grease: A Comparative Study with Traditional Lithium and Calcium Greases

This work compares the thermal, rheological, and tribological properties of a new gel-like biodegradable formulation, prepared using an acylated chitosan thickener and castor oil, with properties exhibited by two conventional greases thickened with lithium and calcium soaps, respectively, taken as benchmarks. Thermogravimetric (TGA), rheological (small-amplitude oscillatory shear [SAOS], rheodestruction, and viscous flow) and tribological (friction and wear analysis) tests, as well as roll-stability measurements were carried out to characterize the three grease samples. In addition, infrared spectroscopy and differential scanning calorimetry (DSC) were used to chemically characterize the acylated chitosan thickener agent. From a thermogravimetric point of view, the new formulation displayed better thermal resistance than the calcium and lithium lubricating greases. The evolution of the linear viscoelasticity functions with frequency and viscosity values in the shear rate and temperature ranges studied were similar to those obtained with the commercial lubricating greases. However, the linear viscoelasticity functions of the biodegradable formulation were slightly more affected by temperature. The mechanical stability behavior and recovery of the rheological functions found in the biodegradable formulation were also better than that exhibited by the calcium-based grease. However, the friction coefficient measured at low rotational speed is slightly higher than that obtained with the benchmarks, with similar or lower values obtained at a high rotational speed. Resulting wear marks obtained after the frictional tests using the acylated chitosan–based grease were larger than those obtained with the commercial greases.     

An assessment of beeswax as a thickener for environmentally friendly lubricating grease production

Environmentally friendly lubricants are preferred in many applications where groundwater or soil pollution is possible. The main purpose of the current study was to evaluate the possibility of beeswax use as a thickener for lubricating greases. European beeswax was used as a thickening material for the preparation of lubricating greases. Rapeseed oil and two mineral oils were used as base oils. The consistency, dropping point temperature, and tribological properties of the prepared lubricating greases were investigated and compared with conventional soap‐thickened greases. The prepared greases exhibited good tribological properties, especially the rapeseed‐oil‐based grease. However, tribological properties of conventional lubricating grease were superior to prepared ones. The weakness of the prepared lubricating greases is their narrow working temperature range. However, the beeswax together with rapeseed oil has great potential in the production of environmentally friendly, completely renewable lubricating greases. Copyright © 2014 John Wiley & Sons, Ltd.     

蓖麻油基含氧化石墨烯润滑脂的制备及其性能研究

以蓖麻油为基础油,以一水氢氧化锂、12-羟基硬脂酸和癸二酸为稠化剂原料,氧化石墨烯(GO)为添加剂,制备3种含GO不同质量分数的混合锂基脂,分别利用锥入度试验器、钢网分油测试仪、滴点试验器、流变仪、热重分析仪、摩擦试验机和三维形貌仪考察其理化性能和润滑性能,探讨GO对蓖麻油基润滑脂的作用机制。结果表明:含GO混合锂基脂的黏度随剪切率和温度的增加均呈非线性减小的变化趋势,但随着剪切速率和温度的升高,GO对蓖麻油基润滑脂的黏度与剪切速率关系和黏温特性影响越来越小;微量的GO能够提高混合脂的热稳定性能;混合锂基脂的平均摩擦因数随GO质量分数的增加呈先减小后增大的变化趋势,适量的GO有助于提高蓖麻油基润滑脂的减摩抗磨性能,这是因为摩擦过程中GO以片层形式进入摩擦副的接触区,能够有效地降低摩擦副表面的直接接触概率,且GO具有自润滑性能,在摩擦副界面上发挥较为有效的润滑作用。     

Conductive Lubricating Grease Synthesized Using the Ionic Liquid

Two kinds of new conductive lubricating greases were synthesized using 1-octyl-3-methylimidazolium hexafluorophosphate and 1-octyl-3-methylimidazolium tetrafluoroborate as base oil and the polytetrafluoroethylene as thickener. The conductivities of the new conductive lubricating greases are higher than the traditional conductive lubricating greases which contains conductive stuffing. In addition, the physical and tribological properties of the new lubricating greases were investigated in detail. The results show that the new lubricating grease show better friction reducing and anti-wear properties than the lubricating grease based on PAO10 at room temperature and 150 °C. The worn surfaces were observed and analyzed by scanning electron microscope and X-ray photoelectron spectroscope. Also, the possible friction mechanisms for the new lubricating greases are proposed.     

Influence of grease rheology on thrust ball bearings friction torque

The friction torque and the operating temperatures in a thrust ball bearing were measured for seven different types of greases, including three biodegradable greases having low toxicity. These friction torque tests were performed using a modified Four-Ball machine.Rheological evaluations of the lubricating greases were made using a rheometer. Bleed oils were extracted from the greases and the dynamic viscosities were measured.In order to compare the performance of the lubricant greases in terms of friction, the grease characteristics were related to experimental results, showing that the interaction between thickener and base oil have strong influences in the bearing friction torque.     

液压往复密封的摩擦特性分析

基于往复式密封的弹性流体动力润滑的数学模型,对影响密封性能的因素进行了综合分析。综合考虑了形变理论、接触力学理论以及流体-固体耦合理论,采用MATLAB数值分析法,通过数学迭代计算完成最终求解。深入研究了润滑油黏度、界面摩擦系数以及密封圈的表面粗糙度对密封性能的综合影响。结果表明:随着耦合界面摩擦系数的增加,接触摩擦力都呈现出增大的趋势;总摩擦力随着粗糙度的增加呈现出抛物线式变化趋势;润滑油的黏度存在一个临界值,当润滑油黏度小于此临界值时,随着润滑油黏度的增加,总摩擦力先增加后降低;当润滑油黏度超过此临界值时,接触摩擦力呈现出单调增加的趋势;润滑油黏度和界面粗糙度的增加会导致流体泄漏的增大。     

润滑脂流变特性与小模数齿轮运转性能相关性研究

采用HAAKE RS6000高级旋转流变仪测试7种润滑脂的屈服应力、弹性模量、黏弹性、触变性和剪切时变性,分析润滑脂流变性对小模数齿轮运转性能的影响。结果表明:润滑脂在齿轮间运转过程中,运转电流和降噪性能与润滑脂流变性具有相关性,受流变特性的影响;稠度接近条件下,基础油黏度最高的润滑脂有最高的电流和最低的噪声;稠化剂含量低的润滑脂对齿轮降噪有利,但是并非稠化剂含量越低越好,稠化剂很少时,其黏附性减弱,齿轮运转过程中,润滑脂不易粘附于齿轮而起到降噪减摩效果。