Sliding Wear of the Hybrid Kevlar/PTFE Fabric Reinforced Phenolic Composite Filled with Nano-titania

The Kevlar/polytetrafluroethylene（Kevlar/PTFE） fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the polymer-based composite.Unfortunately,up to now,published work on the effect of nano-particles on the tribological performance of the fabric composite which can be used as a self-lubricating liner is quite scarce.Therefore,for the purpose of exploring a way to significantly improve the tribological performance of the fabric composite,the tribological performance of the Kevlar/PTFE fabric composite filled with nano-titania is evaluated by using the block-on-ring wear tester.The scanning electron microscopy is utilized to observe the morphologies of worn surfaces of the fabric composites and the counterparts.The tensile properties of the composites are evaluated on the universal material testing machine.The test results show that the addition of nano-titania at a proper mass fraction of the matrix resin improves the wear resistance and the tensile strength,decreases the friction coefficient,and makes the wear volume of the composite reach a relative steady state more quickly;plastic deformation and microcutting are important for the wear of the fabric composite;a lubricating layer is formed on the worn surface of the composite during sliding,and the lubricating layer is critical for the tribological performance of the composite;the formation and properties of the lubricating layer are influenced by the nano-titania particles.The proposed study on the effect of nano-titania on the tribological performance of the Kevlar/PTFE fabric composite,especially on the evolution of the worn surface of the composite,provides the basis for further understanding of the influence mechanism of the nano-particles on the tribological performance of the composite and explores a method of improving the tribological performance of the composite.

Experimental Study on Indoor Air Cleaning Technique of Nano-Titania Catalysis Under Plasma Discharge

In this study, a new technique of air cleaning by plasma combined with catalyst was proposed, which consisted of electrostatic precipitation, volatile organic compounds （VOCs） decomposition and sterilization. A novel indoor air purifier based on this technique was adopted. The experimental results showed that formaldehyde decomposition by the plasma-catalyst hybrid system was more efficient than that by plasma only, Positive discharge was better than negative discharge in formaldehyde removal. Meanwhile, the outlet concentration of ozone byproduct was effectively reduced by the nano-titania catalyst.

A ONE-STEP SURFACE MODIFICATION PROCEDURE TO PEG-GRAFTED NANO-TITANIA

PEG （Polyethylene Glycol）-grafted nano-titania has been obtained in a one-step procedure using hexamethylene diisocyanate as the coupling agent and dibutyltin dilaurate as the catalyst in toluene at 80℃ and characterized qualitatively by FTIR and quantitatively by elemental analysis and thermogravimetric analysis. A comparison of nano-titania with two other commonly used inorganic nanoparticles, nano-silica and nano-alumina, is made, revealing that reactivity order is nano- silica 〉 nano-alumina 〉 nano-titania in view of PEG grafting. Possible mechanism of PEG grafting is also discussed.

Structure transition of nano-titania during calcination

In order to study the structure transition during calcination, nano-titania powders prepared by hydrolyzing precipitation approach and calcined at 300, 400, 500, 600 and 700 ℃ were characterized by XRD, TEM and electron diffraction(ED), respectively. The results show that titania powders calcined below 500 ℃ are almost composed of anatase, rutile appears below 500 ℃ and its ratio increases gradually with increase of calcin temperature; nano-titania particles are smaller than 40 nm mostly and the dispersion is related to calcining temperature; the inter-planar distances of nano-anatase single crystalline change gradually when calcing temperature increases to 500 ℃; so do that of nano-rutile single crystalline when calcining temperature charges from 600 to 700 ℃. The conclusions can be drawn that the temperature of transformation from anatase to rutile is below 500 ℃ and the process carries on gradually. Both inter-planar distances and the structure of nano-titania transform gradually with increasing calcing temperature.

One-pot, solvent-free and efficient synthesis of 2,4,6-triarylpyridines catalyzed by nano-titania-supported sulfonic acid as a novel heterogeneous nanocatalyst

Nano titania-supported sulfonic acid（n-TSA） has found to be a highly efficient, eco-friendly and recyclable heterogeneous nanocatalyst for the solvent-free synthesis of 2,4,6-triarylpyridines through one-pot three-component reaction of acetophenones, aryl aldehydes and ammonium acetate. This reported method illustrates several advantages such as environmental friendliness reaction conditions,simplicity, short reaction time, easy work up, reusability of catalyst and high yields of the products. One new compound is reported too. Furthermore, the catalyst could be recycled after a simple work-up, and reused at least six times without substantial reduction in its catalytic activity.

浅析纳米二氧化钛光催化降解效率的影响因素

本文以罗丹明B(RhB)为目标降解物,研究了锐钛矿型纳米二氧化钛(TiO_(2))的光催化降解效率的影响规律。通过比较不同分散剂对纳米TiO_(2)分散液的分散作用的差别,研究了分散剂对纳米TiO_(2)的光催化降解效率的影响;同时,也探讨了固含量和溶液pH值等因素对纳米TiO_(2)光降解效率的作用规律。结果表明:二氧化钛(TiO_(2))固含量为5 wt%、六偏磷酸钠为0.8%、pH值为5时,目标降解物罗丹明B(初始浓度2.5ppm)在3h后降解效率达到80.25%。将制备的光催化分散液喷涂在大理石瓷砖表面,48 h内降解甲醛效率达到86.9%。

锐钛矿型纳米TiO_2介孔粉体表面织构的研究

以硫酸钛和尿素为原料 ,聚乙二醇 -1 0 0 0为空间构造剂 ,1 0 4℃下经尿素水解均匀沉淀法研制颗粒分散均匀、粒径可控的高热稳定性锐钛矿型纳米 Ti O2 介孔粉体 ,并对其晶相、颗粒大小、比表面积、形貌和孔道结构进行了表征 .结果表明 ,未经任何热处理的 Ti O2 粉体即为锐钛型晶相 ,颗粒为均匀分散的类球型颗粒 ,且颗粒间形成直通型的介孔孔道 ,其孔径在 1 0～ 30 nm之间 .控制焙烧温度可以达到控制颗粒大小及形貌的目的 ,经 85 0℃焙烧 5 h的样品仍保持锐钛矿型晶相 ,未出现向金红石型晶相转变的迹象 .

微波法制备SO_4^(2-)_/TiO_2催化剂及其光催化氧化性能

采用微波法、混合加热法和常规加热法制备 SO_4^(2-)/TiO_2催化剂 ,运用 XRD、 BET、 DRS及 LRS光谱测定等技术对催化剂的结构进行了表征 ,并以光催化降解 C2H4为模型反应考察了不同制备方法对催化剂的光催化氧化反应性能的影响 .研究结果表明 ,微波法制备的 SO_4^(2-)/TiO_2催化剂的光催化氧化性能得到明显改善 ,对乙烯转化率为 80％ ,而混合加热法和常规加热法制备的样品乙烯转化率分别为 58％和 41％ .微波辐射制备的催化剂锐钛矿相含量高、比表面积大 ,光吸收阈值增大；并且拉曼散射光谱向低波数方向移动 ,有助于增加光致电子的跃迁几率 ,提高多相光催化过程的本征量子效率 .

中和水解法制备纳米TiO_2的研究

以Ti(SO4 ) 2 为前驱体 ,氨水为中和剂在常温通过中和水解法合成纳米TiO2 粉体 ,研究了 pH值、物料浓度等因素对产物粒径、晶型和比表面积的影响 ,并采用TEM、XRD、TG/DTA和BET对产物进行了表征 ,结果表明这一方法可以制备颗粒均匀、分散良好的纳米TiO2

纳米TiO_2粉体制备过程中结晶度的控制

采用醇盐水解法，控制醇盐和水的摩尔比和水解的速度等条件，可以制备出５～２０ｕｍ左右的纳米氧化钛粉体．用乙醇洗涤以后，沉淀物转变为无定形；而在乙醇洗涤以前用醋酸处理过的粉体为晶体结构（锐钛矿结构）．不同的处理方法对二氧化钛粉体团聚的影响不同，ＸＲＤ、ＢＥＴ、ＤＴＡ－ＴＧ和ＴＥＭ的研究结果表明，在一定的条件下，经醋酸处理过的粉体表现出优良的性能，晶粒尺寸小，团聚度低，而且失重小，在较低的温度下就进行由锐钛矿向金红石的转变．粉体的这些性能直接影响到材料的烧结特性．

PP/TiO_2纳米复合材料的研制及其抗老化机理分析

制备了聚丙烯 (PP) /TiO2 纳米复合材料 ,用氙灯耐气候试验机对该复合材料进行人工加速老化试验。采用紫外 -可见光光谱法分析了纳米TiO2 等粉体材料的紫外吸收性能 ;分析了PP/TiO2 纳米复合材料的红外光谱并探讨了抗老化机理 ;对比研究了纯PP和PP/TiO2 纳米复合材料老化期间力学性能的变化规律。结果表明 ,纳米TiO2 能赋予PP优异的耐候性能 ,延长制品的户外使用寿命。

纳米TiO_2在涂料中的抗菌性能研究

将实验室自制的抗菌纳米TiO2 添加于苯 丙乳液中 ,制成抗菌涂料。透射电镜测试结果表明 ,表面处理后的抗菌纳米TiO2 在乳液中能够均匀分散 ,可充分发挥纳米TiO2 的杀菌作用。杀菌测试结果表明 ,该抗菌涂料对金黄色葡萄球菌、大肠杆菌、枯草芽孢的杀菌率均达到 99%以上 ,并且它不受光源条件限制 ,抗菌作用彻底、持久。

微波-光催化耦合效应及其机理研究

采用溶胶-凝胶法制备了TiO2和SO42-/TiO2催化剂,运用XRD、BET比表面积测定及微波吸收谱等技术对催化剂的结构进行了表征,并以C2H4为模型反应物考察了微波对催化剂的光催化氧化反应性能的影响.研究结果表明,在微波场中TiO2和SO42-/TiO2催化剂的光催化氧化性能得到明显改善.时间分辨紫外-可见吸收谱证实微波场的存在有效地提高了催化剂对紫外光的吸收率.因此,微波场与紫外光的耦合使光催化活性提高的可能原因是微波场对多缺陷催化剂的极化作用,提高了光致电子的跃迁几率,并在半导体表面形成陷阱中心,降低了电子-空穴对的复合率.

新型的高杀菌纳米二氧化钛/聚丙烯复合材料的结构和物理特性研究

基于一种新型的纳米二氧化钛(TiO2)粉体,利用熔体共混方式制备了纳米TiO2/聚丙烯(PP)复合材料,研究了复合材料的相分散结构、结晶特性、力学性能、杀菌性能和流动性能。结果发现:新型纳米TiO2在聚丙烯中有较好的分散度,绝大多数纳米TiO2在聚丙烯中的聚集体尺寸接近于100纳米;新型纳米TiO2对聚丙烯有一定的结晶成核作用,但并不能提高结晶度;复合材料的力学性能随纳米TiO2含量的增加呈现出拉伸强度下降,伸长率降低,模量和冲击强度上升的趋势。2%纳米TiO2含量的聚丙烯复合材料的综合物理机械性能较好。新型纳米TiO2填充到PP中可以起到良好的抗菌杀菌作用,但也在一定程度上使聚丙烯发生氧化降解,进而导致纳米TiO2/聚丙烯复合材料的流动性略优于纯聚丙烯。

壳聚糖/纳米TiO_2复合涂膜对鲜切荸荠保鲜作用研究

采用壳聚糖/纳米TiO_2作为复合涂膜剂,低温(0～4℃)条件下对鲜切荸荠进行涂膜处理,测定鲜切荸荠贮藏过程中失重率、V_C含量、褐变度(BD)、过氧化物酶(POD)活性等的变化。结果表明:壳聚糖/纳米TiO_2复合涂膜可有效降低果实的水分、V_C等成分的损失,延缓荸荠褐变的发生,从而延长鲜切荸荠的货价保藏期。

制备具有光催化活性的金红石相纳米氧化钛粉体

以TiCl4 为原料,通过控制盐浓度和水解温度可以在温和条件下制备出晶粒尺寸为 6nm的金红石相氧化钛粉体,比表面积为 175m2 /g.测定了粉体的X衍射、红外和拉曼光谱.TEM照片显示粉体呈放射状颗粒,其粒径尺寸在 2 0 0～ 40 0nm.苯酚的光催化降解实验表明它比具有相同比表面积的锐钛矿粉体有更高的光催化活性.

纳米TiO_2/玉米淀粉复合涂膜对圣女果保鲜效果的研究

通过高效分散剂和超声波分散技术,将纳米TiO2均匀分散在玉米淀粉涂膜液中,对圣女果进行涂膜处理,探讨其对贮藏过程中果实失重率、可溶性固形物含量、硬度、腐烂率、VC含量及总酸含量变化的影响,以研究纳米TiO2/玉米淀粉复合涂膜液对圣女果涂膜保鲜的效果。结果表明:随着复合涂膜液中纳米TiO2用量的增加,圣女果的失重率、可溶性固形物含量和腐烂率是先减小后增大,而硬度、VC含量和总酸含量则呈现先增大后减小的变化规律。纳米TiO2用量为0.025%(m/m,以玉米淀粉的质量为基准)时的保鲜效果最好,涂膜后的圣女果在室温(25℃)贮藏11d,其失重率、可溶性固形物含量、腐烂率分别比对照组降低了28.6%、12.7%、78.8%,硬度、VC含量、总酸含量分别是对照组的1.33、1.12、1.34倍。说明纳米TiO2在水果涂膜保鲜方面具有一定的应用前景。

高性能纳米二氧化钛制备技术研究进展

纳米二氧化钛以其优异的性能成为半导体光催化剂的杰出代表,探寻优良的二氧化钛制备工艺有着重要的现实意义。本文主要介绍了近年来国内外纳米二氧化钛制备工艺的研究状况,根据反应体系的物理形态将制备工艺分成气相、液相、固相三大类进行阐述,在此基础上分析比较了不同制备工艺的优缺点,最后展望了今后的发展方向。

硫掺杂纳米TiO_2可见光催化剂的制备及光催化活性

用钛酸丙酯和硫脲为原料在煅烧条件下制备了硫掺杂纳米TiO2光催化剂，用XRD、XPS、TEM和UV—vis吸收光谱对催化剂进行了表征；分别以紫外光与太阳光为光源，甲基橙为目标降解物，评价了催化剂的光催化活性。结果表明，500℃煅烧的硫掺杂TiO2在紫外光区和可见光区的吸光度比纯TiO2提高了约0．23～0．46；经40～50min降解，其在紫外光和太阳光下对甲基橙的降解率比纯TiO2分别提高了32％和69％。TEM结果表明，500℃煅烧的硫掺杂TiO2的粒径约为15～16nm；XRD分析结果表明，硫掺杂能够促进TiO2从锐钛矿相向金红石相的转变，减小催化剂的晶粒粒径；XPS分析结果指出，硫原子的氧化态为＋6，S^6＋部分取代了TiO2晶格中的Ti^4＋，形成了硫掺杂的TiO2光催化剂。

TiO2/硅藻土基多孔陶瓷复合材料的制备及降解甲醛性能

采用固相烧结法和低温煅烧工艺,制备了硅藻土基多孔陶瓷支承体。以四氯化钛为前驱体,采用水解沉淀法在支承体上负载纳米TiO2复合膜。用X射线衍射仪和扫描电子显微镜等对TiO2复合膜/多孔陶瓷支承体的复合结构进行了表征;并以甲醛为降解对象,考察了TiO2复合膜的光催化性能。结果表明:纳米TiO2/硅藻土基多孔陶瓷复合膜在550℃煅烧后TiO2为锐钛矿型,平均晶粒粒径为10.9nm。在紫外光照射240min后,甲醛气体初始浓度由0.463mg/m3降至0.015mg/m3,复合材料对甲醛的去除率达到96.8%。