Surface properties of superfine alumina trihydrate after surface modification with stearic acid

The surface properties of superfine alumina trihydrate （ATH） after surface modification were studied by measuring the contact angle, active ratio, oil adsorption, total organic carbon, adsorption ratio, and Fourier transform infrared （FTIR） spectrum. The contact angle increased initially and then slowly decreased with an increase of the amount of stearic acid. However, the surface flee energy decreased ini- tially and then increased. Surface modification with stearic acid or sodium stearate can benefit from elevating temperature. The base surface tension component and the free energy of Lewis acid-base both declined sharply following the surface modification. Excess stearic acid was physically adsorbed in the form of multilayer adsorption, and an interaction between oxygen on the ATH surface and hydroxyl in stearic acid was subsequently determined. Our results further indicated that the contact angle and adsorption ratio can be used as control indicators for surface modification compared with active ratio, oil adsorption and total organic carbon.

Influence of stearic acid surface modification on flowability and agglomeration of battery grade Li_(2)CO_(3)powder

This work investigates the flow and agglomeration behaviors of battery grade Li_(2)CO_(3)powder and the influence of stearic acid surface modification.The degree of agglomeration is directly related to the uniformity of Li_(2)CO_(3)and its powder mixtures.According to the Chinese National Nonferrous Metal Industry Standard,battery grade Li_(2)CO_(3)powder has D50 equal to 3–8μm which belongs to a micron-sized superfine powder.Therefore,with the extension of storage time,the serious agglomeration phenomenon occurs due to the large specific surface area and rough and irregular powder particles.The Hausner ratio(HR)of the unmodified sample increases from 1.14 to 1.41,and the corresponding flowability is classified as good to poor.Instead,among samples with doping stearic acid,the optimum amount of it is 0.10 wt%which exhibits an extremely stable HR value from 1.14 to 1.16.Meanwhile,after 156 days,the repose angle(AR)obtained for samples without surface modification and using 0.10 wt%stearic acid are calculated to be 49°and 28°,respectively.Based on the values of HR and AR,the flowability of the unmodified sample is poor while the sample modified with 0.10 wt%of stearic acid still maintain excellent powder flow property.Moreover,The LiMn_(2)O_(4)cathode material synthesized from modified Li_(2)CO_(3)powder with a stearic acid content of 0.10 wt%exhibits good crystallinity and comparable electrochemical performance to that prepared by commercial Li_(2)CO_(3).These results indicate that stearic acid has the potential to be an ideal modifier for battery grade Li_(2)CO_(3)powder that needs to be kept for a long time.

Surface Modification of Natural Fibrous Brucite with Stearic Acid

Fibrous brucite,a kind of brucite with unique structure and physical properties,was modified with stearic acid as a surface modifier.In order to investigate the mechanism of surface modification,the fixation of stearic acid on fibrous brucite and the induced changes in surface properties were studied by using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,infrared spectroscopy（IR）,Raman spectroscopy and thermo-gravimetric analysis（TGA）.XRD analysis indicates that the modification of fibrous brucite with stearic acid does not cause any changes in the structure of fibrous brucite mineral.Spectroscopy and thermal analysis show that the surfactant molecules are not only directly adsorbed on the surface of the mineral,but also chemisorbed on mineral surface by forming chemical bonds between the modifier and magnesium hydroxide.

The Studies on the Surface Organic Modification of Tourmaline Powder with Stearic Acid and Its Composite

Stearic acid modified tourmaline powder had been investigated to improve the compatibility and dispersed stability between tourmaline and polymer matrix. The experimental results indicated that the activation index was 100% and contact angle reached 120° when the ratio of the ore slurry is 5:50, the dosage of stearic acid and p-toluenesulfonic acid is 10% and 0.5% (of tourmaline powder’s quantity) respectively with reaction at 80°C for 6.0 h, and the modified tourmaline exhibited an excellent hydrophobic property. The introduction of stearic groups reduced the reunion of tourmaline particles clearly and improved the dispersivity in polymers, and the amount of negative ions released of modified tourmaline increased obviously for both modified tourmaline powders and its composite with polyamide-66 compared to the unmodified tourmaline. Moreover, the structure of modified tourmaline was also characterized by means of Fourier Transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, scanning electron microscope.

INFLUENCE OF SURFACE-MODIFICATION FOR CALCIUM CARBONATE ON THE INTERACTION BETWEEN THE FILLERS AND POLYDIMETHYLSILOXANE

The surface of calcium carbonate(CaCO_3)particles was modified with stearic acid(SA)and the chemical structures of the product were characterized by FT-IR analysis.The interaction between polydimethylsiloxane(PDMS)and CaCO_3 fillers with different surface character was investigated by means of dynamic rheological and bound rubber tests for uncured compounds and mechanical properties measurements for the corresponding vulcanites.The results of dynamic tests indicate that with the increase of SA mass fraction...

钻井液用新型可酸溶加重剂的制备与应用

以羟基磷灰石为原料,六偏磷酸钠为改性剂,制备了一种可酸溶加重剂。采用FTIR对其化学结构进行表征,对改性后加重剂的酸溶性、Zeta电位以及润湿性进行了评价,并对其配制的钻井液的流变性、滤失性以及储层保护效果进行了评价。实验结果表明,10%盐酸作用下改性加重剂的溶解率可达88.27%;采用该改性加重剂的钻井液具有良好的流变性和降滤失性;采用该改性加重剂的钻井液污染的岩心经10%盐酸浸泡2h后,渗透率恢复值>90%,表明改性加重剂参与形成的泥饼可被酸性工作液有效溶解和清除,从而保护储层。

氢氧化镁表面改性及在EVA中的应用

以轻烧粉蒸氨-沉镁制得的氢氧化镁(MH)粉末为研究对象,采用油酸和硬脂酸作为MH表面改性剂,通过对比MH改性前后的吸油值和活化指数发现油酸和硬脂酸的最佳改性工艺条件分别为:油酸用量4%(相对MH粉末质量),改性时间为50 min,改性温度为70℃;硬脂酸用量4%(相对MH粉末质量),改性时间为40 min,改性温度为50℃。通过利用改性前后MH的傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)和热重分析(TG-DTG)、扫描电子显微镜(SEM)、水接触角等表征手段及改性MH在乙烯-醋酸乙烯酯共聚物(EVA)中的添加效果分析对比,结果发现用油酸和硬脂酸对MH改性后添加到EVA中,复合材料的氧指数分别提高了0.7%和1.5%,拉伸强度分别提高了2.3 MPa和1.9 MPa,断裂伸长率分别提高了37.8%和31.1%。由此可以说明改性MH可以有效提高EVA的阻燃性能和力学性能。

环氧大豆油酸-寡聚乳酸修饰纳米羟基磷灰石的制备及其聚乳酸复合材料性能研究

本文采用原位共沉淀法,用环氧化大豆油酸(ESBO)改性纳米羟基磷灰石(n-HA),得到ESBO-HA,将寡聚乳酸(OPLA)接枝在ESBO-HA表面,得到ESBO-OPLA-HA填料,并对其进行系统表征。表征结果表明,ESBO和OPLA成功接枝到n-HA表面。与n-HA相比,ESBO-OPLAHA在有机溶剂中具有更好的疏水性和分散性。通过将Wistar间充质干细胞(MSCs)与系列填料共培养,在较高质量浓度(1.0mg/mL)的填料存在下,培养72h后,ESBO-OPLA-HA对细胞的抑制率低于23.0%。将ESBO-OPLA-HA与PLLA复合,制备得到ESBO-OPLA-HA/PLLA复合材料,表征结果具有参考价值。

双(羟基)金属复合氧化物的表面改性

Mg/Al layered double hydroxide(LDH) was treated with stearic acid by a wet method. The modified double hydroxide showed good dispersion and floatation property with their layer structure being remained almost unchanged.

硬脂酸改性Mg(OH)_2的机理及对EVA性能的影响

采用FTIR表征硬脂酸对氢氧化镁Mg(OH)2的改性效果,发现不存在一个所谓的“最佳量”,分析认为硬脂酸对Mg(OH)2表面改性既包括着硬脂酸—COOH与Mg(OH)2的—OH之间的弱酯化反应,也包含着酸与弱碱Mg(OH)2之间的酸碱反应,所以硬脂酸对Mg(OH)2的表面改性随硬脂酸用量增加而持续进行。此外,改性剂用量也对Mg(OH)2填充乙烯-醛酸乙烯酯共聚物(EVA)体系性能存在显著的影响。与填充未处理Mg(OH)2体系相比较,表面改性剂用量的增加会导致复合材料的拉伸强度的不断下降,断裂伸长率的增加和阻燃性能的急剧恶化。但是,复合材料的表观黏度下降,加工性能得到改善。

利用粉煤灰制取白炭黑及其表面改性研究

以粉煤灰为原料,与碳酸钠碱熔活化生成硅铝酸钠。硅铝酸钠与盐酸反应后,滤液经溶胶-凝胶转变得到产物白炭黑。随即利用γ-MPS硅烷偶联剂和硬脂酸分别对白炭黑分别进行表面改性。借助XRD、TG-DTA、FT-IR光谱、氮吸附等温线等手段对白炭黑改性前后进行表征。结果表明,白炭黑BET比表面积为364.80m2/g,平均孔径为6.02nm。TG-DTA和FT-IR光谱分析显示,两种改性剂成功接枝在了白炭黑表面。对比研究两种改性剂的改性效果发现,γ-MPS的改性效果较好。

硬脂酸改性氧化铈的效果表征与机理研究

采用硬脂酸对氧化铈粉末进行湿法表面改性,通过改性前后粉体的粒度、沉降速度、TEM、FT-IR和DTA分析CeO2的改性效果。结果表明,超细氧化铈经硬脂酸表面改性后,氧化铈粒度较改性之前有所减小,氧化铈颗粒团聚现象较改性前明显降低;提高了在液体石蜡中的分散性,硬脂酸分子在氧化铈表面发生吸附键合,有一部分硬脂酸与超细氧化铈表面发生了化学作用,形成硬脂酸盐,热分析显示改性后的氧化铈表面形成的硬脂酸盐在500℃发生炭化。

硬脂酸对CeO_2纳米粒子的表面修饰研究

利用表面修饰法合成了硬脂酸修饰的 CeO2 纳米粒子,采用透射电子显微镜(TEM)观察了经表面修饰的CeO2 纳米粒子的形貌及分散性,并采用红外光谱(IR)、紫外可见分光光度计等对修饰的CeO2 纳米粒子进行了表征。结果表明:表面修饰剂硬脂酸与 CeO2 纳米粒子表面之间发生了化学键合作用;修饰后的CeO2 纳米粒子表面存在疏水有机基团,阻隔了 CeO2 纳米粒子的团聚,起到了分散作用;同时,修饰后的CeO2 纳米粒子在苯乙烯中的稳定性得到了提高。并且获得了硬脂酸的修饰量与CeO2 纳米粒子的最佳配比。

纳米氧化锌的气流粉碎改性及应用研究

利用气流粉碎改性工艺,以硬脂酸为改性剂,对纳米氧化锌进行解团聚和表面改性,并借助SEM、XRD、FT-IR和激光粒度分析等对改性产品进行了表征,探讨了改性纳米氧化锌在天然橡胶中的应用。结果表明,与改性前相比,改性纳米氧化锌的解团聚效果明显;颗粒表面亲油疏水,在有机溶剂中有较好的分散性;并且能较好地提高天然橡胶的硫化性能和力学性能。证明该工艺对纳米氧化锌进行表面改性是可行的。

硬脂酸纳米粒混悬液表面性质的测定与体外细胞摄取

目的 研究不同表面活性剂制备的硬脂酸纳米粒混悬液的表面性质与体外细胞摄取之间的关系。方法 以不同的表面活性剂采用乳化蒸发 低温固化法制备硬脂酸纳米粒混悬液并测定其表面接触角和表面张力 ,以小鼠腹腔巨噬细胞为细胞模型作体外细胞吞噬实验。结果 用苄泽类Brij 78[聚氧乙烯 (2 0 )硬脂酸醚 ],Myrj 5 3[聚氧乙烯 (5 0 )硬脂酸酯 ],Myrj 5 9[聚氧乙烯 (10 0 )硬脂酸酯 ]和PluronicF6 8[聚氧乙烯和聚氧丙烯嵌段聚合物 ,普郎尼克 188]为表面活性剂制备了粒径分别为 (16 2 .0± 6 7.4) ,(5 0 .2± 2 8.9) ,(32 6 .8± 195 .2 )和 (2 0 4.5± 91.3)nm的硬脂酸纳米粒。体外细胞摄取实验证明 ,各种纳米粒相对于硬脂酸溶液均可增加巨噬细胞对硬脂酸的摄取 ,其中以Myrj 5 9组摄取量最少 ;硬脂酸纳米粒表面的亲水性与巨噬细胞对纳米粒的摄取之间存在着明显的相关关系。

硬脂酸对纳米TiO_2有机表面修饰方法的研究

报道了一种利用硬脂酸对纳米TiO2进行有机表面修饰的新方法,主要包括纳米TiO2水分散液的制备和把纳米TiO2粒子由水分散液中转移到溶有硬脂酸的甲苯溶液中两个过程。采用红外光谱(FT-IR)、X射线光电子能谱(XPS)、热分析(TG-DTA)、透射电镜(TEM)、粒度分布、紫外-可见光谱和分散性实验等对所得的样品进行了表征。红外光谱和X射线光电子能谱说明硬脂酸以双齿配位的方式化学键合在纳米TiO2表面。表面元素分析和热分析数据表明,在纳米TiO2表面的硬脂酸化学修饰层的均匀性和致密性通过本方法得以改善。透射电镜、粒度分布、紫外-可见透过率光谱和分散性实验结果说明,本方法克服了传统方法的缺点,有机表面修饰后的纳米TiO2具有分散性好、团聚粒径小、粒度分布窄、可见光透过率高和紫外线屏蔽能力强的优点。

硫酸钙晶须表面湿法改性研究

采用几种表面改性剂对硫酸钙晶须表面进行了湿法改性试验,选出了改性效果较好的硬脂酸对硫酸钙晶须进行了单因素条件改性试验,分别考察了改性剂用量、初始料浆浓度、改性温度、改性时间、搅拌速率、烘干温度、烘干时间等因素对硫酸钙晶须表面改性的影响;改性硫酸钙晶须产品采用活化指数、接触角、扫描电子显微镜、X射线衍射和红外光谱分析进行表征。试验结果表明:硬脂酸对硫酸钙晶须的改性效果较好,在最佳工艺条件下,改性产品的活化指数为1.00,接触角为123.6°。建立了硬脂酸与硫酸钙晶须的作用模型。

纳米氧化锌的合成及表面改性

以硫酸锌、尿素为原料,采用均相沉淀法合成了纳米氧化锌.研究了硬脂酸对所制的纳米氧化锌粉体表面改性的机理及其对粉体亲油性的影响.实验结果表明,硬脂酸中的羧基与纳米氧化锌粉体颗粒表面的羟基发生了酯化反应,并在表面形成单分子膜.经过表面改性的纳米氧化锌由亲水性转化为亲油性.同时,就纳米氧化锌粉体硬脂酸表面改性反应,探讨了反应摩尔分数、反应温度和反应时间对产物的影响,从而筛选出粉体亲油性最大的反应条件为:硬脂酸质量分数为7%;反应温度为50℃;反应时间为1h.

造纸污泥的表面改性及其作用机理的初步研究

采用9种改性试剂对造纸污泥进行表面改性，通过分析改性产物的活化指数，得出改性效果最佳的试剂是硬脂酸。通过正交实验和单因素实验探讨了硬脂酸改性造纸污泥的适宜工艺条件，利用傅里叶红外光谱仪（FT-IR）对硬脂酸改性造纸污泥的作用机理进行了初步分析。结果表明，当硬脂酸用量（对污泥绝干质量）为4．0％、污泥悬浮液质量分数为8．O％、反应温度为60～70℃和反应时间为20min时，改性污泥的活化指数可达99％以上；硬脂酸与造纸污泥颗粒发生了化学结合，在污泥颗粒表面产生了新的基团。

硬脂酸对纳米ZnO的有机表面修饰研究

利用硬脂酸对纳米ZnO进行有机表面修饰;采用红外光谱(IR)、热分析(TG-DTA)、透射电镜(TEM)、润湿性实验、分散性实验等手段对表面改性前后的纳米ZnO进行表征。红外光谱和TEM表明,在纳米ZnO表面包覆有硬脂酸的有机层;热分析显示,包覆量约为18.98%;润湿性实验及分散性实验表明,经硬脂酸改性的纳米ZnO的表面由亲水性变为亲油性。