超细氧化铝水悬浮液分散稳定性研究

阴离子聚电解质分散剂(PAA)使α-Al2O3粉体的等电点降低;超声分散作用改善了分散剂在粒子表面的分布状态,因而使浆料的流变性有明显的改善;离子强度低于0.08mol/L时,浆料的粘度随离子强度提高而增加,稳定性降低.但在0.08～0.12mol/L的范围内,离子强度对浆料粘度的影响不明显;温度对浆料的粘度有显著的影响.分散剂添加量低于饱和吸附添加量时,温度升高,浆料粘度增加,稳定性下降.而在分散剂添加量高于饱和吸附添加量时,温度升高,粘度则降低.     

复配分散剂对ZrO2悬浮液稳定性的影响

本实验选用由乳化剂OP(壬基酚聚氧乙烯醚)与CPB(溴代十六烷基吡啶)所组成的复配分散剂对纳米ZrO2 进行分散,制备ZrO2 悬浮液,并讨论了复配分散剂两组分用量比、pH值、悬浮液中的离子强度等对悬浮液稳定性的影响.结果表明:加入复配分散剂得到的ZrO2 悬浮液,具有更好的分散稳定性;当OP与CPB用量比为1∶ 1,复配分散剂用量为ZrO2 含量的6%时,能使ZrO2 粉末具有良好的分散,在pH=1.8时,悬浮液颗粒粒径最小,中位粒径达到178 nm.实验中还发现,添加复配分散剂后悬浮液等电点由原来的pH= 6右移到pH=13附近,另外,增加悬浮液中的离子强度,使Zeta电位值降低,粒径增大,但离子强度大小并不会影响ZrO2 的等电点,其等电点仍保持在13左右.     

PVP对CA-H2O-Al2O3悬浮液稳定性的影响

利用柠檬酸(CA)与聚乙烯吡咯烷酮(PVP)复配为二元分散剂,研究其对水基氧化铝悬浮液稳定性的影响。结果表明,pH为9.0时,仅添加0.2 wt%的CA/PVP即可稳定分散固含量为45 v%的氧化铝悬浮液,且浆料为牛顿流体,流变性很好。固含量越高,悬浮液的粘度越大,对pH值越敏感,悬浮液能分散稳定的pH值范围越窄,对于不同的体系,获得最佳流变性时的pH值也不同。     

水介质中高浓度电解质离子对纳米氧化锆悬浮稳定性的影响

研究了高浓度电解质离子对纳米ZrO2悬浮液稳定性的影响.对悬浮液及清液进行Zeta电位和吸光度测定,通过TEM分析,结果表明:加入大量的电解质后,纳米ZrO2的表面双电层受到压缩,ζ-电位几乎为零,只调pH值不能使纳米ZrO2悬浮起来;组成简单、分子量小的分散剂受电解质离子的影响,容易从颗粒表面脱落下来,起不到空间位阻的作用;结构复杂、分子量大的分散剂在高浓度的电解质溶液中起到很好的空间位阻作用.     

凹凸棒石粘土-NH4PAA-水悬浮液流变性研究

研究了聚丙烯酸铵(NH4PAA)用量、离子强度等对凹凸棒石粘土的流变性影响。研究表明，在凹凸棒石粘土悬浮液中添加NH4PAA分散剂可使粘土流变性获得很大的改善。pH为8．5时，添加量为4．5％NH4PAA分散剂，可以制备分散良好的凹凸棒石粘土悬浮液，而且pH提高，分散剂最佳添加量减少。电解质NaCl使凹凸棒石粘土的流变性下降。但NaCl浓度从0．5mol／L变化到1．0mol／L时悬浮液的流变性基本不变。     

聚环氧琥珀酸/聚乙烯吡咯烷酮对Al_2O_3/SiC悬浮液流变性能的影响

利用阴离子型分散剂聚环氧琥珀酸(polyepoxysuccinic acid,PESA)/非离子型分散剂聚乙烯吡咯烷酮(polyvinylpyrrolidone,PVP)复配为二元分散剂,对Al2O3/SiC悬浮液的流变性能进行了研究。结果表明:在碱性条件下,添加复合分散剂PESA/PVP的Al2O3/SiC悬浮液比加入单一分散剂的体系有更好的分散性。当复合分散剂总添加量为0.4%(质量分数)、PESA与PVP质量比为3∶1时,Al2O3/SiC悬浮液的黏度最低。添加二元分散剂的Al2O3/SiC悬浮液能在25%(体积分数)~45%的固含量范围内保持稳定。添加PESA/PVP作为分散剂的Al2O3/SiC悬浮液的抗电解质性能优于单一PESA作为分散剂的悬浮液。PESA与PVP通过静电斥力与空间位阻的协同效应,极大提高了Al2O3/SiC悬浮液的稳定性。     

分散剂对钴蓝颜料悬浮液分散性的影响

通过改变体系pH值和分散剂的添加量,对钴蓝颜料水悬浮体系的zeta电位、稳定性、分散性以及流变特性进行研究.结果表明:pH值和分散剂对钻蓝水分散体系的稳定性和分散性有显著影响.对于体积分数为2.0％的钴蓝悬浮液,分散剂用量超过钴蓝质量分数的1.0％时,体系具有较好的分散性.悬浮液的粘度和分散剂的最佳用量随钴蓝固含量的增加而增加.     

分散剂对有机蒙脱土悬浮液分散稳定性的影响

研究通过重力沉降法、Zeta电位分析法以及粘度分析,研究了二癸基二甲基氯化铵(DDAC)以及不同复配分散剂对有机蒙脱土在水溶液中的分散行为,以及pH值对有机蒙脱土分散稳定性的影响。结果表明:有机蒙脱土悬浮液的分散稳定性随着DDAC浓度的增加呈现先增后减的趋势;不同高分子分散剂与DDAC复配后,降低了悬浮液的Zeta电位,但却提高了体系的空间位阻效应,当悬浮液体系的pH值为8～11范围内时,体系的稳定性提高。     

十二烷基三甲基氯化铵/纳米凹土悬浮体系流变学行为研究

将十二烷基三甲基氯化铵添加到纳米凹土水悬浮液体系,研究其对流变性的影响,考察因素为固含量、分散剂量和离子强度。当体系中未添加十二烷基三甲基氯化铵时,流变曲线为牛顿型流体,随着分散剂的添加,流变学行为符合塑性流体特征。剪切速率一定时,悬浮液的黏度随着分散剂的增加而变大。当离子强度达到0.20mol/L,悬浮液的流变曲线为牛顿型流体,体系黏度不随剪切速率的增加而变化。     

组合电解质对氧化铁-水悬浮液流变特性的影响

应用LVDV-Ⅲ＋型可编程流变仪测定了组合电解质对氧化铁—水悬浮液的流变特性的影响。实验结果表明,一价、二价组合电解质在改善悬浮液流变性的同时会使悬浮体系粘度有较大降低;三价组合电解质在改善悬浮液流变性的同时不会使悬浮体系粘度有较大增加。凝聚氧化铁—水悬浮液在测定范围内表现出伪塑性流体的特征。     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

典型煤碳燃烧特性研究和数值模拟

本文以三种典型煤的碳燃烧为研究对象，分别采用简单一维沉降燃烧方式和等温加热燃烧方式，实验研究了煤在快速加热条件下，其碳的初期和中，后期燃烧过程。以实验为基础，建立了煤的碳燃烧模型，变工况数值模拟了煤的碳燃烧过程，揭示了煤不同条件下的单颗粒碳燃烧特性。     

用两个形状指数表征粉煤灰颗粒形貌的研究

引用两个形状指数表征颗粒形状的概念,即先将颗粒形状近似为椭圆,再将椭圆图像分离:以圆为基准的颗粒宏观形状指数δ;以光滑椭圆为基准的颗粒轮廓凹凸度,即微观形状指数ζ。分析和发展了近似椭圆模型。并运用图像分析仪对粉煤灰、水泥样品进行实验。结果表明,粉煤灰颗粒的两个形状指数δ和ζ都大于水泥颗粒。证明粉煤灰颗粒的球形度、表面光滑度优于水泥,而且,随着粒径增大,δ和ζ呈下降趋势,表明磨制颗粒越粗。(?)粒形状越不规则。文中还运用近似椭圆模型再现了颗粒的模拟图像。