高岭土微粉与纳米TiO2表面复合改性研究

采用sol0-gel法对清细处理过的高岭土微粉与纳米TiO2进行了表面复合改性进行研究,结果表明,改性高岭土结构没有改变,其白度显著提高,改性后的高岭土对红外光的遮挡能力明显增强,对紫外光的吸收能力亦大大提高。     

高岭土的机械化学改性及其对聚乙烯的补强性能

采用机械研磨和表面改性的方法,制备了硅烷接枝高岭土粉体。利用粒度分析仪、红外光谱分析和沉降性能测试等进行表征。研究结果表明:机械研磨提高了硅烷与高岭土的反应活性,使其在液体石蜡中具有良好的分散稳定性,与直接改性高岭土相比,沉降体积由3.2mL提高到7.6mL。将高岭土原矿、直接改性高岭土和磨剥改性高岭土分别与聚乙烯熔融共混制备复合材料。研磨改性高岭土对聚乙烯具有良好的补强性能,并且在填充量为10份时达到最佳,材料的拉伸强度较纯聚乙烯提高了3.7MPa。     

乳液聚合法制备有机改性高岭土/聚苯胺复合材料及其性能研究

以十六烷基三甲基溴化铵为有机化改性试剂,对高岭土进行改性,再以苯胺为单体,十二烷基苯磺酸为掺杂剂与乳化剂,过硫酸铵为引发剂,采用乳液聚合法制备有机改性高岭土/聚苯胺复合材料。结果表明,利用四探针技术测试发现,随着有机改性高岭土掺量的增加,复合材料电导率逐渐下降;FT-IR分析证明采用乳液聚合法可实现高岭土有机化改性及其与聚苯胺原位复合;TGA分析结果表明,复合材料耐热性能随改性高岭土引入量的增加而逐渐增强,当掺量为50%(质量分数)时,聚苯胺的分解起始温度和失重最快温度分别提高了13℃和36℃;采用SEM分析证明二者复合成功;XRD分析说明改性高岭土与聚苯胺的复合仅通过物理吸附作用而未发生插层。     

纳米高岭土的热稳定性能研究

以纳米高岭土的热失重曲线为基础,研究了粒径、改性剂种类对热失重温度的影响,并进行了热分解动力学研究.研究结果表明:与高岭土原矿相比,纳米高岭土的热分解起始温度提高,活化能略有下降,热稳定性变化不大;经过改性处理后,高岭土达到纳米级的分散,粒子表面具有较高的表面原子与体相原子比和众多的表面缺陷,易造成晶格松驰,因此起始分解温度下降,活化能也降低,热稳定性下降;三种改性方法中,复配改性对高岭土的稳定性影响最大,硅烷偶联剂改性影响最小.     

高岭土表面改性及技术加工现状

高岭土储量丰富,价格便宜,是一种重要的化工原材料,我国是高岭土资源大国。高岭土作为聚合物的功能性填料时,不仅能降低聚合物产品的成本,还能提高其力学性能、耐热性、阻燃性。但是高岭土与聚合物两者相容性差,容易在聚合物基体中发生团聚,需要对其表面改性才能分散均匀于聚合物基体中。本文介绍了高岭土改性的方法以及改性高岭土填料的应用,提出了高岭土改性存在的问题及发展建议。     

聚丙烯/改性煤系高岭土复合材料的制备与性能

煤系高岭土经过硅烷偶联剂表面改性后,与聚丙烯(PP)树脂熔融共混制备出聚丙烯/改性煤系高岭土复合材料。通过X射线衍射、红外光谱、力学性能和扫描电镜分析,研究了改性煤系高岭土的填充量对复合材料力学性能的影响。结果表明,利用硅烷偶联剂可以实现煤系高岭土的表面改性。改性煤系高岭土填充量为3%时,复合材料具有最佳的冲击韧性。填充量为5%时,复合材料的断裂伸长率达到最大值。随着改性煤系高岭土填充量的增加,复合材料的弯曲强度和弯曲模量逐渐增大,填充量为10%时,二者比纯PP分别提高14.5%和27.5%。     

球磨法疏水改性高岭土及其性能研究

以聚(甲基氢硅氧烷)(PMHS)作为疏水改性剂,采用球磨法对高岭土进行疏水改性,制备具有高疏水性能的改性高岭土。通过激光粒度和Zeta电位分析仪、接触角测量仪、FT-IR、SEM、TEM、XRD、DSC对改性后的高岭土进行了表征。结果表明,在球磨机械力作用下,高岭土的粒径和Zeta电位分别由1237nm和-28.12mV降至439nm和-10.53mV,晶型结构遭到破坏。高岭土的接触角由0°迅速增长为130~144°,表现出较强的疏水性能。PMHS以物理吸附或化学吸附的方式覆积于高岭土的表面,以提高热稳定性能。     

复合改性对聚磷酸铵填充EVA材料抗渗性能的影响

利用高岭土与聚磷酸铵(APP)进行复配,使用二甲基硅油对复配后阻燃填料进行表面改性处理,并利用接触角及红外分析对阻燃剂抗渗性能提高的机理进行分析。结果表明:优化复配比例及改性条件为:高岭土以质量分数30%的复合比例与APP复合、有机改性剂二甲基硅油使用量质量分数最优条件为2.0%,改性温度95℃。改性后阻燃剂抗渗析性得到显著提高,渗析率由1.81%减小至0.61%。     

高岭土的湿法球磨改性及其填充橡胶复合材料的力学性能

以湿法球磨改性高岭土、炭黑、白炭黑作为原材料,对天然橡胶、丁苯橡胶进行填充,制备了橡胶复合材料,主要考察了浆液浓度、改性剂类型、改性剂用量对高岭土粒度的影响,以及填料用量、填料类型、填料配合对橡胶复合材料力学性能的影响.结果表明:高岭土浆液浓度为20％,KH-Si69用量为2.8％时获得最小粒径的改性高岭土;高岭土填充橡胶与纯橡胶相比,其拉伸强度和撕裂强度有较大提高;高岭土的补强作用明显,跟白炭黑相当,与炭黑仍有一定差距;填料配合填充丁苯橡胶时,高岭土可部分替代炭黑、完全替代白炭黑,有效降低制品的生产成本.     

煅烧高岭土/硅藻土复合填料表面改性研究

研究了表面改性剂配方、用量、改性时间等对煅烧高岭土 /硅藻土复合填料表面改性效果的影响以及表面改性剂与煅烧高岭土 /硅藻土复合填料表面的作用机理。     

TiOSO4热水解法制备超细TiO2粉末光催化剂

采用TiOSO4热水解法制备超细TiO2粉末光催化剂,探讨了不同制备条件对光催化性能的影响,采用XRD、TEM、BET、TG－DTG－DTA对催化剂进行表征,初步说明TiO2光催化活性与其晶型、粒径大小、比表面等微结构的关系。实验结果表明,在160℃热处理下制备的TiO2粉末是球形和多孔型结构,比表面积约为170m^2/g,只有锐钛型单一晶相和无定型组成,颗粒平均粒径为20nm,其光催化活性与商业化Degussa P25 TiO2超细粉末相近。     

Sol-Gel法制备纳米TiO2过程中水解pH值的影响及其性能表征

采用钛酸四异丙酯[Ti(i-OC3H7)4]水解法制备纳米TiO2粉体，水解过程中有很多参数对纳米TiO2的特征产生影响，通过控制制备过程中的水解pH值，可以得到不同粒径和不同晶型的纳米TiO2粉体，本文主要探讨了纳米TiO2晶型转变的条件和晶粒度Dhkl随pH值变化的趋势，并利用XRD，TEM对粉体颗粒的形貌，大小，物相组成进行分析，XRD分析研究表明，纳米的A→R相变和水解pH值密切相关。     

Microemulsion-mediated hydrothermal synthesis of photocatalytic TiO2 powders

A reverse microemulsion-mediated hydrothermal route has been employed to synthesize photocatalytic titanium dioxide (TiO2) powders. Nano-crystalline monophasic anatase TiO2 powders were successfully prepared when the microemulsion-derived precursors were hydrothermally treated. The advantage of using this microemulsion mediated hydrothermal route is the significant reduction in reaction time and temperatures as compared with the conventional hydrothermal process. The oil/water emulsion ratio significantly affected the particle sizes of the obtained TiO2 powders. The specific surface area of TiO2 powders was increased with the oil/water ratio, thereby leading to enhanced photocatalytic activity of TiO2 powders. As the hydrothermal temperature was elevated, the morphology of the TiO2 particles changed from a rod-like shape into a polyhedral shape. The variation in microstructures decreased the specific surface area of the TiO2 powders and lowered the photocatalytic activity.     

Fabrication of dye-sensitized solar cell (DSSC) using different particle sizes of TiO2 deposited via nano-particle deposition system (NPDS)

TiO2 layers were fabricated using a nano-particle deposition system (NPDS) on transparent conductive oxide (TCO) glass for dye sensitized solar cells (DSSCs). Conventionally, TiO2 paste for working electrodes has been fabricated using paste type methods. The fabricated paste composed of a mixture of nano-sized TiO2 powders, binders and solutions is then painted on TCO glass. After drying, the TiO2 layer on TCO glass is sintered to make a path for electron transfer. TiO2 layers formed by this paste type method require numerous steps, which can be time consuming. In this study, TiO2 powders were sprayed directly on TCO glass using NPDS in order to simplify the fabrication steps. To improve porosity and produce scattering layers, commercial nanocrystalline TiO, powders with different sizes were alternately deposited. Moreover, powders with different sizes were mixed and deposited on the TCO glass. The results indicate that the DSSCs with a TiO2 layer composed of different particle sizes had better cell performance than the cells assembled with single-sized TiO2 particles. Therefore, this study shows that a dry TiO2 coating process is possible for DSSC fabrication to improve its cell efficiencies, and this method can easily be applied on flexible substrates since NPDS is a room-temperature deposition process.     

Preparation and characterization of photoactive composite kaolinite/TiO(2)

Preparation of nanocomposite kaolinite/TiO(2), using hydrolysis of titanyl sulfate in the presence of kaolin was addressed. A variable (kaolin)/(titanyl sulfate) ratio has been used in order to achieve the desired TiO(2) content in prepared nanocomposites. Calcination of the composites at 600 °C led to the transformation of the kaolinite to metakaolinite and to origination of metakaolinite/TiO(2) composites. The prepared samples were investigated using X-ray fluorescence spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry and diffuse reflectance spectroscopy in the UV-VIS region. Structural ordering of TiO(2) on the kaolinite particle surface was modeled using empirical force field atomistic simulations in the Material Studio modeling environment. Photodegradation activity of the composites prepared was evaluated by the discoloration of Acid Orange 7 aqueous solution.     

TiO_2-聚吡咯复合材料的制备及光催化性能

采用原位氧化聚合法制备TiO2-聚吡咯复合材料,研究吡咯与TiO2配比对TiO2-聚吡咯复合材料在紫外光和太阳光下光催化降解甲基橙的影响,利用傅里叶红外光谱仪、X射线衍射仪、紫外-可见光谱仪对样品进行表征。结果表明,TiO2-聚吡咯复合材料与纯聚吡咯相比,聚吡咯本征态特征峰和C─N伸缩振动峰峰值都向高波数偏移,TiO2和聚吡咯的复合并不是单纯的物理复合,而是产生了化学作用力;通过改变吡咯的添加量,可以控制聚吡咯在TiO2粉体表面的包覆量,聚吡咯的包覆对TiO2的晶型没有影响;聚吡咯对TiO2的包覆可降低TiO2的禁带宽度至2.90 eV,使TiO2-聚吡咯复合材料可吸收的波长范围拓宽到可见光区,提高复合材料在可见光下的光催化能力;适量的聚吡咯包覆可以提高TiO2-聚吡咯复合材料的光催化活性,以紫外灯作为光源催化降解甲基橙,当吡咯包覆质量分数为0.06时,复合材料的电子-空穴对分离效果最好;以太阳光作为光源催化降解甲基橙,当吡咯包覆质量分数为0.04时,复合材料的光谱拓展效果最好。     

Preparation and enhanced daylight-induced photocatalytic activity of C,N,S-tridoped titanium dioxide powders

A simple method for preparing highly daylight-induced photoactive nanocrystalline C,N,S-tridoped TiO2 powders was developed by a solid-phase reaction. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra, N2 adsorption-desorption measurements and transmission electron microscopy (TEM). The photocatalytic activity was evaluated by the photocatalytic oxidation of formaldehyde under daylight irradiation in air. The results show that daylight-induced photocatalytic activities of the as-prepared TiO2 powders were improved by C,N,S-tridoping. The C,N,S-tridoped TiO2 powders exhibited stronger absorption in the near UV and visible-light region with red shift in the band-gap transition. When the molar ratio of CS(NH2)2 to xerogel TiO2 powders (prepared by hydrolysis of Ti(OC4H9)4 in distilled water) (R) was kept in 3, the daylight-induced photocatalytic activities of the as-prepared C,N,S-tridoped TiO2 powders were about more than six times greater than that of Degussa P25 and un-doped TiO2 powders. The high activities of the C,N,S-tridoped TiO2 can be attributed to the results of the synergetic effects of strong absorption in the near UV and visible-light region, red shift in adsorption edge and two phase structures of un-doped TiO2 and C,N,S-tridoped TiO2.     

煅烧高岭土-TiO_2复合材料的制备及表征

以煅烧高岭土和TiO2为原料,采用机械力化学法制备煅烧高岭土-TiO2复合材料。以遮盖力和吸油量为指标,优化煅烧高岭土-TiO2复合材料的制备工艺,并表征其颜料性能。结果表明:复合过程中共混研磨时间、球料质量比和搅拌磨转速对复合材料的颜料性能影响显著。制备的煅烧高岭土-TiO2复合材料遮盖力为纯钛白粉的88.4%,白度也与其接近,且吸油量适中。该材料用于内墙涂料显示出较好的颜料性能,能以一定比例替代钛白粉使用。     

四氯化钛水解法制备二氧化钛纳米晶的影响因素

研究了四氯化钛水解法制备的二氧化钛纳米晶工艺中水解８温度和硫酸根离子对粉体性能的影响室温下的水解产物为无定形结构,这种粉体有着很大的比表面积,其孔为介孔尺度;添加少量的硫酸根离子使粉体的孔径在２～５ｎｍ,最可几孔径为３．８ｎｍ,提高水解温度能得到金红石与锐钛矿相的混晶,同样的水解温度下,添加少量的硫酸根离子则为纯锐钛矿相,用到金红石与锐钛矿相的混晶,同样的水解温度下,添加少量的硫酸根离子则为纯锐钛     

TiO_2纳米粉体的溶胶-凝胶工艺制备和光催化活性表征

通过溶胶 -凝胶工艺制备了锐钛矿型TiO2 纳米粉体 ,TiO2 粉体由 40～ 80nm的球形颗粒组成。XPS研究表明 :TiO2 纳米粉体中主要含有Ti和O元素 ,未发现其它杂质元素 ,O/Ti的原子比为 2 .14,其中含有一定量的羟基 (-OH)。甲基橙水溶液的光催化降解实验表明 :溶胶 -凝胶工艺制备的锐钛矿型TiO2 纳米粉体的光催化活性明显高于普通TiO2 粉体。