Modified zinc silicate — an active rubber filler

Physico-chemical properties have been characterized for zinc silicates obtained in various conditions in reaction of sodium metasilicate solution with water soluble zinc salt (zinc sulphate or chloride). Attempts have been made to apply the precipitated zinc silicates in rubber mixtures based on butadiene-styrene rubber. Appropriate tests have been conducted. Also, a possibility has been tested of eliminating zinc oxide (an activator in the vulcanization process) from the rubber mixture. Studies have been presented on the modification of zinc silicate surface with silane and titanate coupling agents. The extent of surface modification has been estimated measuring heats of surface immersion and determining chemisorbed carbon on the surface which has originated from coupling agents. The effect of modifying zinc silicate surface has been evaluated by strength tests performed on vulcanizates filled with the modified silicates.     

表面疏水纳米碳酸钙制备及表征

采用3-氨丙基三乙氧基硅烷（APTES）、3-巯丙基三乙氧基硅烷（MPTES）、3-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）3种硅烷偶联剂,对纳米碳酸钙进行表面改性,制备了具有表面疏水性能的纳米碳酸钙。采用红外光谱仪器与接触角测定仪对玫性前后的纳米碳酸钙进行了表征与比较,结果表明：硅烷偶联剂能成功连接到纳米碳酸钙表面;3种硅烷改性剂中,KH570改性后的接触角最大,改性效果最好;表面疏水改性有助于提高纳米碳酸钙在亲油相和在有机相中的分散性能。     

The effect of surface modification on physicochemical properties of precipitated silica

The main goal of this study was to obtain hydrophobic silica whose properties would allow their application as plasto- and elastomer fillers. Thus, hydrated silica was modified by silane and titanate coupling agents. The modification procedure and appropriate modification apparatus were developed. The degree of silica surface modification was evaluated by different methods. As grounds for this evaluation, changes in the physicochemical properties, brought about by the condensation reaction of surface silanol groups with alkoxyl or hydroxyl groups of the molecules of coupling agents, were used. The degree of hydrophobicity of the silica surface was determined on the basis of the heat of immersion of this surface, and silanol groups were identified by the infrared spectroscopy. Moreover, changes in the tendency to form agglomerates and aggregates of molecules were studied by microscopy. It was found that modification with silane and titanate coupling agents leads to an increase in silica activity. Application of these agents results in the change of the hydrophilic character to the hydrophobic one. This revised version was published online in November 2006 with corrections to the Cover Date.     

阻燃剂水镁石的表面改性研究

使用铝酸酯、钛酸酯、硬脂酸3种偶联剂对水镁石进行表面改性。阐述了改性剂用量、时间和温度等因素对水镁石改性的影响。硬脂酸用量5%,改性温度80℃,改性时间80min条件下,产物性能最优良,活化指数达到96.2%。钛酸酯用量1%,改性温度60℃,改性时间50min条件下,产物性能最优良,活化指数达到98.2%。铝酸酯用量1%,改性温度70℃,改性时间50min条件下,产物性能最最优良,活化指数达到98.8%。使用XRD、FTIR和TG-DSC对改性前后的水镁石进行表征。分析结果表明改性剂对水镁石的改性机理是:改性剂分子与水镁石表面的羟基形成氢键而吸附在水镁石的表面,从而改善了水镁石与聚合物的相容性能。     

重质碳酸钙/硅灰石复合填料表面改性研究

研究了表面改性剂配方、用量、改性时间等对重质碳酸钙／ 硅灰石复合填料表面改性效果的影响，以及表面改性与复合填料表面的作用机理     

不同偶联剂改性PTW对PP/GF复合材料性能的影响

目的研究六钛酸钾晶须表面改性对聚丙烯复合材料的力学性能影响,以探索最佳表面改性手段。方法分别采用硅烷偶联剂KH550、KH570、正十二烷基三甲氧基硅烷,钛酸酯偶联剂NDE311、改性六钛酸钾晶须(PTW),然后将改性过的六钛酸钾晶须、玻璃纤维、聚丙烯通过熔融共混制得聚PP/GF/PTW复合材料。结果比较六钛酸钾晶须经不同偶联剂改性前后对聚丙烯/玻璃纤维复合材料性能的影响,发现改性过的六钛酸钾晶须可改善复合材料的力学性能。比较不同偶联剂改性六钛酸钾晶须对聚丙烯/玻璃纤维复合材料性能的影响,发现经KH550偶联剂处理后,与未改性相比,复合材料的弯曲性能提高了58.63%,拉伸性能提高了16.07%,冲击性能提高了63.1%。结论六钛酸钾晶须经KH550偶联剂处理后,复合材料的综合性能最好。     

偶联剂处理滑石粉填充聚乙烯薄膜的研究

目的确定最佳偶联剂及其用量,以改进聚乙烯薄膜的综合性能。方法采用铝酸酯、钛酸酯、硬脂酸等偶联剂对滑石粉进行表面改性,通过测定改性后滑石粉的接触角、活化率以及红外光谱等方法对改性效果进行评价。并将改性后的滑石粉与聚乙烯共混后进行吹塑薄膜,测定薄膜的力学性能。结果采用偶联剂改性滑石粉后,表面从亲水性变为疏水性,其中钛酸酯表面改性效果较好。表面改性提高了滑石粉填充聚乙烯薄膜的力学性能。结论使用质量分数为2%钛酸酯改性的滑石粉作为填充粉体时,聚乙烯薄膜的综合性能较好。     

Immobilisation of fully sulfonated polyaniline on nanostructured calcium silicate

Up to 7.4% (w/w) of the sulfonated polyaniline, poly(2-methoxyaniline-5-sulfonic acid) (PMAS) can be absorbed onto nanostructured calcium silicates. Spectroscopic and leaching studies on the novel PMAS-silicate nanocomposites obtained indicate that attachment of the PMAS occurs via electrostatic binding of PMAS sulfonate groups to Ca2+ sites on the silicates. The surface area and pore volume of the nanocomposites are comparable to those of pure silicate and increase the surface area of the PMAS polymer by several orders of magnitude. The PMAS emeraldine salt in the nanocomposites retains its chemical reactivity, being readily oxidised and reduced to its pernigraniline and leucoemeraldine forms, respectively. The conductivity of the composite is comparable to that of the pure PMAS, several orders of magnitude higher than that of dried nanostructured calcium silicate.     

Formation of Janus TiO2 nanoparticles by a pickering emulsion approach applying phosphonate coupling agents

Anisotropic surface modification of TiO2 nanoparticles was achieved applying a Pickering emulsion approach. TiO2 nanoparticles were prepared by sol-gel routes which allowed an excellent control over their size and morphology. The obtained colloids were further used as stabilizers in the formation of oil-in-water Pickering emulsion. For reasons of comparison, also commercially available titanium dioxide nanoparticles (Evonik AEROXIDE TiO2 P25) were used in the functionalization experiments. An organophosphorus coupling agent present in the oil phase coordinated to the surface of the anatase nanoparticles. In such a way an anisotropic surface modification of the particles was achieved which increased the stability of the Pickering emulsion. Spectroscopic studies revealed the presence of organophosphorus coupling agents which exhibited a covalent bonding to the surface of the particles. Thermogravimetric analyses confirmed a lower surface coverage of the particles modified in emulsion compared to those modified in suspension. Reactions of organophosphorus coupling agents containing an additional methacrylate group applying an organic monomer (methyl methacrylate) as the oil phase of the Pickering emulsion resulted in hybrid TiO2@polymer spheres. Spectroscopic characterization of the resulting particles revealed that the phosphonates were coordinated to the TiO2 surface and at the same time copolymerized with the MMA within the oil droplet. Morphological investigations of the isolated final product showed that the material was composed of polymer spheres with the stabilizing TiO2 nanoparticles on their surface.     

Use of coupling agents as a route to improvement of the compressibility of fine zirconia and alumina powders

In order to improve the compressibility of fine zirconia and alumina powders, powders were surface-treated with aluminate, silane and titanate coupling agents. The surface modification reduced both powder/powder friction and powder/die-wall friction, which increased the density of the compacts. At 2% additions, the effectiveness of the coupling agents on density increase was in the order, silane > titanate > aluminate. In zirconia systems with different titanate concentrations it was found the optimum amount of coupling agent could be approximated by the amount required for monolayer coverage on the powder surface.     

纳米碳酸钙表面处理对PVC／CaCO3性能的影响

采用硬脂酸与硅烷偶联剂表面处理、PMMA水解接枝处理等方法对CaCO3进行表面改性,考察改性纳米钙对PVC／CaCO3复合材料力学性能的影响。     

超细氧化铝粉体的表面改性研究

利用两种硅烷偶联剂、三种钛酸酯偶联剂对Al2O3粉体颗粒表面有机改性,比较了不同偶联剂对颗粒表面的改性效果,结果表明硅烷偶联剂未能对粉体表面进行有效的有机改性.红外光谱分析证实了偶联剂NTC401在Al2O3粉体表面进行了化学吸附,而偶联剂JSC和CT136在Al2O3粉体表面主要发生物理吸附.电镜照片说明,经NTC401改性的Al2O3粉体粒子之间的团聚得到了有效改善,而经JSC和CT136改性的Al2O3粉体粒子之间的团聚未得到改善.机理分析认为中心钛原子六配位的结构能够有效阻止颗粒团聚.     

超细二氧化硅的改性及其在润滑油中的应用

超细二氧化硅由于其优良的摩擦学性能,在润滑油添加剂领域倍受关注。本文介绍了超细二氧化硅的表面结构特征、表面改性机理及常用的改性方法,着重介绍了醇酯法、硅烷偶联剂法及表面聚合物接枝改性法,并对其改性趋势作了进一步探究。最后概述了超细二氧化硅在润滑油中的应用,并展望了其在润滑油中的应用发展趋势。     

新型碳酸钙湿法改质剂XH-CS01的研制及应用研究

以复合材料界面作用的机理为指导,研制了一种适合于碳酸钙湿法改性用的改质剂XH-CS01,并研究了该改质剂在碳酸钙湿法改性及在聚乙烯增韧改性中的应用效果。研究结果表明,该改质剂可以以一种乳液的状态方便地分散在水中,并能够跟水相中的碳酸钙颗粒表面发生化学反应,通过该法制备的活性碳酸钙的流动性好。相对对比试验表明,改性碳酸钙填充的聚乙烯树脂的力学性能明显高于干法及其他偶联剂的改性效果,尤其是冲击强度方面,通过XH-CS01湿法改性获得的碳酸钙,可以使填充量为30%左右的聚乙烯体系冲击强度达到基体树脂的3倍以上,从而在一定的添加范围内实现了“增强增韧”的双重效果,避免了昂贵的弹性增韧所带来的模量和强度下降的缺点。     

Surface modification and characterization for dispersion stability of inorganic nanometer-scaled particles in liquid media

Abstract

Inorganic nanoparticles are indispensable for science and technology as materials, pigments and cosmetics products. Improving the dispersion stability of nanoparticles in various liquids is essential for those applications. In this review, we discuss why it is difficult to control the stability of nanoparticles in liquids. We also overview the role of surface interaction between nanoparticles in their dispersion and characterization, e.g. by colloid probe atomic force microscopy (CP-AFM). Two types of surface modification concepts, post-synthesis and in situ modification, were investigated in many previous studies. Here, we focus on post-synthesis modification using adsorption of various kinds of polymer dispersants and surfactants on the particle surface, as well as surface chemical reactions of silane coupling agents. We discuss CP-AFM as a technique to analyze the surface interaction between nanoparticles and the effect of surface modification on the nanoparticle dispersion in liquids.     

短切炭纤维表面改性及其增强聚四氟乙烯复合材料性能的研究

采用偶联剂对短切炭纤维表面改性,然后和聚四氟乙烯（ＰＴＦＥ）粉料混合,冷压成型,烧结固化等手续制备了短切炭纤维增强ＰＴＦＥ复合材料。研究了不同类型偶联剂,其最佳用量和表面改性的工艺条件。结果表明,复合材料的力学性能和耐化学腐蚀性能均优于同类材料。     

Physicochemical studies on precipitated magnesium silicates

In this study, an attempt was made to obtain highly dispersed magnesium silicates which could be employed as polymer fillers or active adsorbents. Due to numerous applications of magnesium silicates and silicates of other metals, three procedures were suggested for production of their synthetic equivalents. The precipitation processes were optimized in respect to temperature, reagent dosing rate, rate of mixing them, substrate concentration, etc. In the process of magnesium silicate precipitation 5% solutions of sodium metasilicate (water glass) and magnesium sulphate(VI) were used. In order to broaden application range of synthetic magnesium silicates they were subjected to surface hydrophobization (for the purpose non-ionic surfactants were used) and surface modification (using silane pro-adhesive compounds). All the unmodified and modified samples were subjected to a broad physicochemical analysis. Chemical composition of unmodified magnesium silicates was determined using atomic adsorption spectrometry. In addition particle diameters were estimated in all the samples. Effective particle diameter, polydispersity were defined, particle size distributions were estimated using dynamic light scattering (DLS technique). Principal adsorptive properties were established to check up whether the obtained in laboratory synthetic magnesium silicates can be applied as adsorbents. This was executed by determination of nitrogen adsorption/desorption isotherms on the surface of magnesium silicates. Moreover, taking advantage of the isotherms, specific surface area, diameter and volume of pores were estimated.     

Calcium silicate cements obtained from rice hull ash: A comparative study

This work describes the utilization of rice hull as raw-material for the preparation of two calcium silicates namely, β-Ca_1.91Ba_0.04SiO₄ and β-Ca_1.96Ba_0.04SiO₄. The synthesis was completed at 800°C. Hydration rate and compressive strength of mortars prepared with the two calcium silicates were studied and compared to mortars prepared with commercial Portland cement. Hydration rates for both silicates, studied by thermogravimetric and FTIR analysis are very similar; after 60 days the hydration rates are around 42–43% and reaches 75% after 270 days. Compressive strength experiments were performed using test specimen prepared with commercial Portland cement as reference, and blends of Portland cement and the two calcium silicates, at replacement levels of 10 and 20%. Results have shown that after a 90 days curing period, the compressive strength of the reference and the blends containing 10% of each of the calcium silicates show the same behavior. Using a replacement level of 20% there is a small decrease in compressive strength. This behavior is attributed to the lower hydration rate of these calcium silicates.     

铝酸酯偶联剂的合成及其对PVC／L－CaCO_3和HP／L－CaCO_3的改性作用

通过异丙醇铝与相应的有机酸反应，合成了４种单核型铝酸酯偶联剂。粘度法测定结果表明，它们对碳酸钙粒子均有很好的表面改性作用。初步试验表明，有３种铝酸酯可明显提高软质ＰＶＣ／Ｌ－ＣａＣＯ_３共混物的力学性能，但４种铝酸酯对ＰＰ／Ｌ－ＣａＣＯ_３共混物的力学性能均无改善，说明铝酸酯的偶联作用不但与它们的分子结构有关，而且和偶联的对象有关。     

沉积型煅烧高岭土表面改性与应用试验研究

沉积型高岭土是中国特有的高岭土资源。应用试验证明,沉积型高岭土经超细粉碎、煅烧、超细磨矿和硅烷偶联剂表面处理后,作为高性能电缆胶料的填料,填充性能得到明显的改善。