Reactivity and antimicrobial properties of nanostructured titanium dioxide

The photo-induced reactivity of three nanostructured titanium dioxides including TiO₂ nanoparticles (i.e., nano-TiO₂), titania–silica aerogel and nanotextured TiO₂ film, were investigated for gas phase photocatalytic oxidation of trichloroethylene and inactivation of Bacillus subtilis and Escherichia coli microbial cells. A correlation was observed between photoreactivity for TCE conversion and bactericidal activity within TiO₂ of similar nanostructures and composition (i.e., elemental and phase). This indicates that the photogenerated radical species from UV-irradiated TiO₂ responsible for TCE photo-oxidation also play a major role in the inactivation of microbial cells. The superb bactericidal activities of titania–silica aerogels (i.e., up to 6log reductions in viable B. subtilis) and nanotextured TiO₂ film (3.4log reduction) compared to commercial Degussa P25 TiO₂ (0.64log reduction) and optimum nano-TiO₂ (1.3log reduction) far exceeds the observed activity enhancement for TCE photo-oxidation. This implies that nanoscale chemical and structural environment also contribute towards the bactericidal activities.     

Modifications of paper and paperboard surfaces with a nanostructured polymer coating

Organic nanoparticles synthesized by imidization of styrene-maleic anhydride copolymers are deposited as a top-coating onto paper and paperboard substrates from a stable aqueous dispersion with maximum solid content of 35 wt.%. The morphology, physical characteristics and chemical surface properties of the coatings are discussed in this paper, using scanning electron microscopy, atomic force microscopy, contact angle measurements and Raman spectroscopy. Due to the high glass transition temperature of the polymer nanoparticles, a unique micro- to nanoscale structured coating is formed that favourably improves the gloss, printing properties (ink-jet printing test and off-set printing test), surface hydrophobicity (maximum water contact angle 140°) and water repellence (reduction of Cobb-values). The interaction of the nanoparticle coatings with the cellulosic paper web results in improvement of the mechanical paper strength and is attributed to hydrogen-bonding between the nanoparticles and the cellulosic fibers.     

Modifications of paper and paperboard surfaces with a nanostructured polymer coating

Organic nanoparticles synthesized by imidization of styrene-maleic anhydride copolymers are deposited as a top-coating onto paper and paperboard substrates from a stable aqueous dispersion with maximum solid content of 35 wt.%. The morphology, physical characteristics and chemical surface properties of the coatings are discussed in this paper, using scanning electron microscopy, atomic force microscopy, contact angle measurements and Raman spectroscopy. Due to the high glass transition temperature of the polymer nanoparticles, a unique micro- to nanoscale structured coating is formed that favourably improves the gloss, printing properties (ink-jet printing test and off-set printing test), surface hydrophobicity (maximum water contact angle 140°) and water repellence (reduction of Cobb-values). The interaction of the nanoparticle coatings with the cellulosic paper web results in improvement of the mechanical paper strength and is attributed to hydrogen-bonding between the nanoparticles and the cellulosic fibers.     

Interaction between titanium dioxide pigments and hindered piperidine/anti-oxidant combinations in the photostabilisation of polypropylene

The complex interaction between titanium dioxide pigments, a primary anti-oxidant and a hindered piperidine compound in the photostabilisation of polypropylene has been examined using infrared absorption spectroscopy. The hindered piperidine compound, Tinuvin 770, was found to be ineffective in protecting the polymer against the photocatalytic action of anatase. In the case of rutile good photoprotection of the polymer was observed, the effect being greater for a coated pigment. However, the presence of the anti-oxidant, Irganox 1010, antagonised the stabilising action of the hindered piperidine compounds, the effect being greater in the presence of an uncoated pigment. The results are discussed in terms of additive adsorption onto the pigment particle surface versus the photocatalytic activity of the pigment. The effects were also found to be dependent on the ultraviolet content of the light source.     

Dilute solution properties of flexible polymers in toluene: A comparison of commercially available photometers

Dilute solution properties of polystyrene and poly(α-methylstyrene) in toluene have been measured using several of the commercially available instruments for intensity light scattering. Results are compared among the instruments used and with literature values. Relative advantages and disadvantages of the instruments are discussed.     

节能防腐钛纳米聚合物涂料的应用与涂装

介绍了钛纳米聚合物涂料在炼油厂油汽冷却器管束上的应用状况.分析表明,与未经防护的碳钢水冷却器相比,使用钛纳米聚合物涂层的冷却器管束,可节约资金16.3万元/(台·年);与采用7910涂料的冷却器管束相比,可节约资金12万元/(台·年).经国家有关部门鉴定,该项技术在我国水冷器和冷凝器管束防腐防垢技术方面,达到了国内领先水平.     

装饰层压纸用钛白粉技术现状的研究

本文针对装饰层压纸用钛白粉技术要求,综述了国内外装饰纸用钛白粉的技术现状,着重指出了提高装饰层压纸用钛白粉耐光性能的包膜方法。     

Activity, stability and inhibition of a bioactive paper prepared by large-scale coating of laccase microcapsules

Enzyme immobilization on paper by large-scale processes may play a valuable role in the development of economical and widely distributed biosensors. In this study, we report on the coating of laccase from Trametes versicolor on papers using a laboratory coater (Cylindrical Laboratory Coater) that simulates realistic conditions similar to those obtained with industrial coaters. In order to achieve an efficient retention of laccase in the coating, the enzymes were incorporated in poly(ethyleneimine) microcapsules. The microcapsules were suspended in a starch-based coating suspension, applied on paper by blade coating at a rate of 500 and 800 m/min thereupon dried by evaporation using an IR lamp at 36 kW. A technique based on the colorimetric reaction between the laccase and its substrate, p-phenylenediamine (PPD), was developed to evaluate the activity of the immobilized enzyme. Our results show that the use of microencapsulation allows for better activity retention in papers over time at room temperature (50% loss after 28 days) compared to papers modified with free laccase (50% loss after 4 days). Microcapsules also decrease the inhibition of laccase by azide.     

以钛精矿和钛渣为原料制备硫酸法钛白粉的对比分析

通过研究钛精矿与钛渣在性质上的不同,结合国内外学者的研究状况,综合论述了钛渣、钛精矿分别在后续制备硫酸法钛白粉中存在的成本、物料平衡、酸解工艺、水解工艺的优劣,钛渣相比钛精矿在综合成本上优势更明显,为进一步促进钛渣利用的发展,可以从生产工艺和环保两方面双管齐下。结合酸解与水解工艺表明,采取钛渣与钛精矿混合酸解,合理控制其总钛液n（铁）/n（钛）,同时优化工艺参数,可以得到高品质的钛白粉。     

Theoretical study of the scattering efficiency of rutile titanium dioxide pigments as a function of their spatial dispersion

We propose an original theoretical framework to model the scattering efficiency of white paint films as a function of the volume fraction and spatial state of dispersion of rutile titanium dioxide pigments, taking into account electromagnetic couplings. Numerical calculations are performed using a multiple T matrix formalism on an “elemental” volume extracted from the bulk of the paint and which we model as pigments and fillers in a polymer matrix. Qualitative studies show that, due to the dependent scattering phenomenon, the size of fillers can modulate the magnitude of loss in scattering efficiency by modifying the spatial state of dispersion of the pigments in the polymer matrix. In particular, fillers whose size is comparable to the dimension of the pigments improve the scattering efficiency by impeding crowding. It is also shown that the optical properties of the bulk material at arbitrary concentration can be approximated by extrapolating the optical properties calculated on a limited number of scatterers.     

Structure and properties of composite films prepared from cellulose and nanocrystalline titanium dioxide particles

Composite films were successfully prepared from cellulose and two kinds of nanocrystalline TiO₂ particles in a NaOH/urea aqueous solution (7.5 : 11 in wt %) by coagulation with H₂SO₄ solution. The structure, morphology, and properties of the films were characterized by transmission electron microscopy, scanning electron microscopy, X‐ray diffraction, TGA, tensile testing, UV–vis spectroscopy, and antibacterial test. The results indicated that TiO₂ particles in a cellulose matrix maintained the original nanocrystalline structure and properties. TiO₂(I) (anatase) and TiO₂(II) (the mixture of anatase and rutile) particles exhibited a certain miscibility with cellulose. The tensile strength of two kinds of composite films was higher than 70 and 75 MPa, when the content of TiO₂(I) and TiO₂(II) was 4 and 11 wt %, respectively. The cellulose composite films containing nanocrystalline TiO₂ particles displayed distinct antibacterial abilities and excellent UV absorption. This work provides a potential way for preparing functional composite materials from cellulose and inorganic nanoparticles in a NaOH/urea aqueous solution, without a destruction of the structure and properties of the particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3600–3608, 2006     

The interaction between zinc oxide and titanium dioxide in water

A mechanism is proposed for the reaction between zinc oxide and titanium dioxide in water. Between certain limits of weight ratios of zinc oxide and titanium dioxide definite increases in viscosity, pH, and sedimentation volumes with time have been observed which support the belief that tridimensional structures are formed from the individual particles. The same mechanism may be responsible for some of the thickening in emulsion paints containing these mixed pigments. A laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S.D.A.     

Reaction between titanium dioxide and carbon in flowing helium stream

Abstract

The reaction between titanium dioxide and carbon in a flowing helium stream was studied by scanning electron microscopy and X-ray diffraction. Experimental results indicate that the order of phase transformations during the reaction was TiO₂(rutile) → Ti₄O₇ → Ti₃O₅ → Ti₂O₃ → TiO → TiC. A mechanism is proposed to explain the overall reaction. The reaction rate was found to increase with increasing sample thickness, reaction temperature, and initial bulk density and with decreasing helium flowrate, molar ratio of TiO₂/C, and grain size of titanium dioxide.     

A study of the corrosion resistance of a waterborne acrylic coating modified with nano-sized titanium dioxide

The incorporation of nano-sized inorganic pigment particles into organic coatings may offer the potential for improving many of their properties, including corrosion resistance, at relatively low loadings. In the present research, titanium dioxide with a crystallite size of 5-10 nm was added to a waterborne organic primer formulation at loadings from 0.1 to 5% (w/w) and applied to hot-dip galvanized steel (HDG) panels. The corrosion resistance of the modified coatings was measured by neutral salt spray corrosion testing and electrochemical impedance spectroscopy (EIS), with an unpigmented film tested for comparison. 3% (w/w) TiO₂ appeared to produce an optimum improvement in the corrosion resistance.     

箱式压滤机在钛白粉生产中的应用

介绍了钛白粉生产中酸解渣的产生和利用情况，目前对钛白生产过程中产生的酸解废渣进行固液分离主要采用传统的稀释法，该工艺存在钛液回收率偏低和产生大量洗水的缺点。叙述了应用过滤设备的新工艺情况，利用箱式压滤机分离钛白生产酸解过程中产生的酸性残渣，结果为：钛液的回收率达91．8％，较该装置上马前提高3．6％，结果表明该装置能较完全提取残渣中钛液，提高钛白收率，同时沉降底部残渣中的钛液经分离后不会被稀释，降低残渣的含水量，便于残渣综合利用。     

二氧化钛光触媒在金属镀膜与金属防护技术中的应用第一部分光触媒分散技术

介绍了二氧化钛的晶体类型和基本性质、典型的锐钛型二氧化钛的XRD图谱。对纳米粒子的团聚现象进行了解释。对纳米粒子的分散原理——高分子分散剂／界面活性剂分散和电解质分散进行了说明。分别介绍了水溶液中二氧化钛以及改性后的锐钛型纳米二氧化钛的Zeta电位与pH的关系。研究了锐钛型纳米二氧化钛在聚丙烯酸盐分散介质中的粒径分布。结果表明,在此分散介质中,纳米颗粒的分布比较集中,粒径小于50．7 nm的粒子占60％,其平均粒径远低于传统的涂料级和颜料级分散的粒子;该溶液呈现明显的丁达尔现象,光触媒活性高,在实验室存放24个月后质量稳定;将此溶胶涂至玻璃表面,所得涂膜透明度高。     

Theoretical analysis of light scattering properties of encapsulated rutile titanium dioxide pigments in dependent light scattering regime

Using numerical simulation, we study and compare the optical properties of model systems representing three types of scatterer: (a) standard TiO₂ pigments, (b) standard TiO₂ pigments encapsulated by a hard polymer shell and (c) standard TiO₂ pigments encapsulated by a layer of air and a polymer shell. Calculations are performed taking into account multiple and dependent light scattering regimes. Assuming an equivalent amount of TiO₂ in each system, results show that a standard TiO₂ pigment particle encapsulated by air could be a better opacifier than a standard un-encapsulated TiO₂ pigment because the presence of air could provide: (a) additional volume to the existing particle to scatter light; (b) better redistribution of the scattered field in the backward hemisphere; (c) a scattering cross-section less affected by crowding and (d) spacing effects due to the presence of the thin hard polymer shell which is required to encapsulate the air layer. Nonetheless, results also suggest that such benefits could probably not be exploited in real paint systems as encapsulated TiO₂ would only be more efficient than standard TiO₂ in a range of pigment volume filling fractions (PVC) that would not generate enough scattering efficiency to yield complete hiding as required by international standards.     

Influence of titanium dioxide pigments on the optical properties of polycarbonate and polypropylene for diode laser wavelengths

In laser transmission welding of polymers, additives and colorants could influence the welding result. In this work, polypropylene and polycarbonate probes colored with titanium dioxide (TiO₂) pigments of various concentrations are investigated. The probes are produced using an extrusion process to obtain a homogeneous distribution of colorants. The TiO₂ pigments change the optical properties of the polymers considerably. The measured reflectance increases with increasing pigment load while the transmittance decreases. From the measured data of transmittance, reflectance, and collimated transmittance, the scattering, the absorption coefficient, and the anisotropy factors are calculated. It is shown that the scattering coefficient at 1530 nm (laser) wavelength is smaller than for 968 nm, while the absorption coefficient is negligible for both wavelengths. Scattering coefficient and anisotropy factor are used to simulate the propagation of the laser radiation in the polymers. The influence of the scattering process on the beam propagation is represented by the change of the power density distribution. It is shown that the maximum intensity of the distribution is reduced more than the transmittance with increasing pigment concentration. The effect is higher for 968 than for 1530 nm wavelength making the larger wavelength more favorable for transmission welding. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40073.