The effect of nano‐ and micro‐TiO2 particles on reflective behavior of printed cotton/nylon fabrics in vis/NIR regions

To match the reflectance profile of desert colors including brown, olive green, and khaki in the Vis/near IR (NIR) bands, several pigments were used to print cotton/nylon fabrics. The reflectances of printed fabrics were measured by using spectrophotometric technique. TiO₂ microparticle and nanoparticle powders were also added to the printing pastes to evaluate their effect of reflectance, light, rubbing, washing fastnesses, and colorimetric values of each sample. Tuning the reflectance behavior of each color was successfully managed using specific pigments along with TiO₂ particles. NIR reflectance of brown, khaki, and olive green printed fabrics was enhanced by presence of TiO₂ in printing formulations, which is in complete agreement with the Kubelka–Munk theory. NIR enhancing effect of TiO₂ particles was fast against rubbing, washing, and light exposures while it could significantly change the visible appearance of the printed patterns even at concentrations as low as 0.25 g/kg. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012     

Decomposition of gas‐phase aromatic hydrocarbons by applying an annular‐type reactor coated with sulfur‐doped photocatalyst under visible‐light irradiation

BACKGROUND: Unlike many water pollution applications, visible‐light‐driven photocatalysis of gas‐phase pollutants has been reported only rarely. The present study was performed to investigate the feasibility of applying S‐doped visible‐light‐induced TiO₂ to treat gas‐phase aromatic hydrocarbons, using a continuous air‐flow annular‐type reactor. RESULTS: The prepared S‐enhanced TiO₂ powders, along with a commercially available TiO₂ powder (Degussa P‐25), were characterized using diffuse reflectance UV‐VIS‐NIR spectrophotometry, Fourier transform infrared (FTIR) spectrophotometry, X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetry (TG) analyses. A photocatalytic activity test exhibited an increasing trend in degradation reaction rates with increase in flow rate but a decreasing trend in terms of degradation efficiencies. Several experimental conditions induced reasonably high decomposition efficiencies with respect to toluene, ethyl benzene and o,m,p‐xylenes (close to or above 90%), although benzene exhibited a somewhat lower decomposition efficiency. CONCLUSIONS: The S‐doped TiO₂ and undoped P25 TiO₂ powders exhibited different catalyst characteristics. The results demonstrate that an annular‐type reactor coated with visible‐light‐activated S‐doped TiO₂ can serve as an effective tool to treat gas‐phase aromatic hydrocarbon streams. Copyright © 2009 Society of Chemical Industry     

Influence of crystallite size on color properties and NIR reflectance of TiO2@NiTiO3 inorganic pigments

Crystallite size may significantly impact optical properties of inorganic pigments. However, limited studies have so far been reported in this area. In this work, TiO₂@NiTiO₃ complex pigments were synthesized by precipitation-calcination method. Results showed that the increase in calcination temperature led to the formation of TiO₂@NiTiO₃ pigments with crystallite sizes from 29 to 82.6 nm but similar morphologies and aggregate particle sizes (around 1 μm). The yellow component (b*) significantly increased by 7 with crystallite size, but the integrated NIR reflectance decreased slightly (4.02%). Also, the characteristic absorption of NiTiO₃ pigments in NIR region declined the integrated NIR reflectance values.     

The comparative study of photocatalytic self‐cleaning properties of synthesized nanoscale titania and zirconia onto polyacrylonitrile fibers

The photocatalytic activity of TiO₂ and ZrO₂‐coated polyacrylonitrile (PAN) fibers was compared through the self‐cleaning of methylene blue and eosin yellowish. TiO₂ and ZrO₂ nanocrystals were successfully synthesized and deposited onto PAN fibers with photocatalytic self‐cleaning activity using the sol‐gel process at low temperature. The pristine and treated samples have been characterized by several techniques, such as scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The TiO₂ nanoparticles with 10–20 nm in size, and ZrO₂ with 20–40 nm have been synthesized to form dispersed particles on the fiber surface, which shows photocatalytic properties when exposed to UV–Vis light. The photocatalytic activity, tested by measuring the degradation of adsorbed methylene blue and Eosin Y. Photocatalytic activity of TiO₂‐coated fibers toward dyes degradation was higher than that of ZrO₂‐coated fibers. This preparation technique can be also applied to new fabrics to create self‐cleaning and UV irradiation protection properties in them. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Surface topography and cooling effects in poly(vinyl chloride) (PVC)/titanium dioxide (TiO<Subscript>2</Subscript>) composites exposed to UV-irradiation

Rutile titanium dioxide (TiO₂), at different amounts (0, 1, 3, 5, 8 and 10 phr), was used to prepare PVC/TiO₂ composites as cool materials. Exposure to the ultraviolet (UV)-irradiation at 65 °C (black-panel thermometers) with a xenon arc as the light source (0.51 W/(m² nm), 340 nm) for 200, 400 and 600 h resulted in the formation of polyene structure in PVC and causing discoloration. Besides, atomic force microscopy and roughness measurements were used to examine the changes in surface topography and roughness before and after UV-irradiation. Ethylenic index was used to characterize the aging degree of composites. The contact angle value of composites became smaller and their polarity increased after exposing to UV-irradiation, but the presence of TiO₂ effectively prevented this process. In addition, exposure to UV-irradiation had little effect on the reflectance of PVC/TiO₂ composites over the whole solar wavelength range (200–2500 nm), especially in near infrared (NIR) region (700–2500 nm). This allowed the TiO₂-loaded samples to display an excellent cooling property whether indoors or outdoors. The addition of higher quantities of TiO₂ led to higher efficiency of the cooling effect. In general, this study provides strong support for the property of long-term outdoor use of PVC/TiO₂ composites with high solar reflectance and excellent cooling performance.     

Diffuse reflectance behavior of the printed cotton/nylon blend fabrics treated with zirconium and cerium dioxide and citric acid in near- and short-wave IR radiation spectral ranges

Near- and short-wave IR emission spectra of printed cotton/nylon blend fabrics coated with inorganic compounds in order to tune their diffuse reflectance behavior to the ones with woodland and desert backgrounds are investigated. In this regard, cotton/nylon blend fabrics printed with a four-color digital pattern were used as the substrate, and different concentrations of zirconium and cerium dioxide (ZrO₂ and CeO₂) with and without citric acid as a cross-linker were loaded on these fabrics using the pad-dry-cure method. The diffuse reflectance of the coated fabrics with various concentrations of nanoparticles and a cross-linker was first measured by near-infrared (NIR) diffuse reflectance spectroscopy (DRS). Then, fabrics with an optimum concentration of nanoparticles and appropriate reflectivity profiles similar to woodland and desert were investigated by field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), washing, and rubbing fastness properties. In general, NIR and short-wave infrared (SWIR) reflectance of fabrics coated with ZrO₂ and CeO₂ nanoparticles in range of 1% to 1.5% (w/v [%]) was suitable for matching with different environments. According to the findings obtained from the durability test, it was concluded that the washing fastness of the treated fabrics with CeO₂ nanoparticles was excellent in both environments. FE-SEM images of the treated fabrics containing ZrO₂ and CeO₂ indicated that the presence of nanoparticles on the surface of fabrics in woodland patterns was greater than the desert ones. However, the coated fabrics with CeO₂ and citric acid in the woodland pattern have shown better dispersion with a mean particle size of 30 to 60 nm.     

Synthesis and characterization of novel nontoxic BiFe1−xAlxO3/mica-titania pigments with high NIR reflectance

A series of novel nontoxic near-infrared (NIR) reflective pigments based on Al-doped BiFeO₃ coated mica-titania were synthesized by precipitation combined with sol-gel method. The pigments of the formula BiFe_1−xAl_xO₃/mica-titania (x = 0, 0.1, 0.2, 0.3, 0.4) were characterized by XRD, FE-SEM, TG-DTA, UV–vis–NIR spectrophotometer and CIE L^* a^* b^* color scales. The results illustrate that the BiFeO₃ nanoparticles are coated on the surface of mica-titania uniformly, and the doped BiFe_1−xAl_xO₃/mica-titania is similar to BiFeO₃/mica-titania composite in morphology. Furthermore, the absorption edge of composite pigments shift to shorter wavelength (533–495 nm) can be attributed to O_2p-Fe_3d charge transfer transitions and change the color of the pigments from brown to orange. Additionally, the NIR solar reflectance of the powdered pigments and pigmented coatings were measured. The results reveal that with the increase of progressive doping of Al³⁺ for Fe³⁺, the NIR solar reflectance of the pigments increase gradually and exhibit higher NIR solar reflectance (R* ≥ 47.8%) than the conventional pigment of similar color. Moreover, we also evaluated the thermal and chemical stability of the pigments. In conclusion, the pigments have the potential to be applied as “cool pigments”.     

Structures and properties of the polyester nonwovens coated with titanium dioxide by reactive sputtering

Nanoscale titanium dioxide (TiO₂) films were deposited on the surface of polyester nonwovens by using direct current (DC) reactive magnetron sputtering. The effect of coating thickness on the surface structures and properties of TiO₂ coated fabrics was investigated by atomic force microscope (AFM), X-ray diffraction (XRD), energy dispersive X-ray analysis system (EDX), scanning electron microscope (SEM), and antistatic test in this article. The results indicated that the grain sizes of the sputtered clusters increased and the coating layer became more compact as film thickness was increased, but the crystal structure did not have any significant change. At the same time, the film mechanical properties and antistatic performance in general depended strongly on the film thickness which could lead to the optimum thickness for a particular application.     

Multifunctional properties of polyester fabrics modified by corona discharge/air RF plasma and colloidal TiO2 nanoparticles

In this study the possibility of tailoring the textile nanocomposite materials based on the polyester fabric and TiO₂ nanoparticles that can simultaneously provide desirable level of antibacterial activity, UV protection, and self‐cleaning effects with long‐term durability was investigated. To enhance the binding efficiency of colloidal TiO₂ nanoparticles, the surface of polyester fabrics was activated by low‐pressure RF air plasma, and corona discharge at atmospheric pressure. Obtained functionalized textile materials provided maximum antibacterial efficiency against gram‐negative bacterium E. coli. High values of UV protection factor (UPF) indicate the maximum UV blocking efficiency (50+) of these fabrics. The results of self‐cleaning test with blueberry juice stains and photodegradation of methylene blue in aqueous solution confirmed excellent photocatalytic activity of TiO₂ nanoparticles deposited on the fiber surface. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Photoactive behavior of polyacrylonitrile fibers based on silver and zirconium co‐doped titania nanocomposites: Synthesis,characterization, and comparative study of solid‐phase photocatalytic self‐cleaning

Silver and zirconium co‐doped and mono‐doped titania nanocomposites were synthesized and deposited onto polyacrylonitrile fibers via sol–gel dip‐coating method. The resulted coated‐fibers were characterized by X‐ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, thermogravimetric analysis, and BET surface area measurement. Photocatalytic activity of the TiO₂‐coated and TiO₂‐doped coated fibers were determined by photomineralization of methylene blue and Eosin Y under UV–vis light. The progress of photodegradation of dyes was monitored by diffuse reflectance spectroscopy. The XRD results of samples indicate that the TiO₂, Ag‐TiO₂, Zr‐TiO₂, and Ag‐Zr‐TiO₂ consist of anatase phase. All samples demonstrated photo‐assisted self‐cleaning properties when exposed to UV–vis irradiation. Evaluated by decomposing dyes, photocatalytic activity of Ag–Zr co‐doped TiO₂ coated fiber was obviously higher than that of pure TiO₂ and mono‐doped TiO₂. Our results showed that the synergistic action between the silver and zirconium species in the Ag‐Zr TiO₂ nanocomposite is due to both the structural and electronic properties of the photoactive anatase phase. These results clearly indicate that modification of semiconductor photocatalyst by co‐doping process is an effective method for increasing the photocatalytic activity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Solar spectral properties of PVC plastisol‐based films filled with various fillers

Plastisol is mostly a suspension of PVC particles in a liquid plasticizer that flows as a liquid and can be poured into a heated mold. For PVC plastisol applications, in addition to liquid dispersion performance and post‐dispersion flocculation resistance, outdoor durability is an important end use requirement. Spectral properties of PVC plastisol‐based films with or without additional near infrared (NIR) rays barrier fillers have been investigated. Both spherical and lamellar fillers have been incorporated in PVC plastisol at a weight content of 2% to 10% and results show a high impact on the reflectance in the NIR region and on the transmittance in the visible (Vis) region. Experimental results showed that the incorporation of nacre lamellar‐based filler in PVC plastisol did not permit favorably change its spectral properties while TiO₂‐based particles ensured a decrease of the transmittance in the Vis and an increase of the reflectance in the NIR. J. VINYL ADDIT. TECHNOL., 25:E188–E194, 2019. © 2018 Society of Plastics Engineers     

Surface modification of TiO2/SiO2 composite hydrosol stabilized with polycarboxylic acid on Kroy-process wool fabric

Self-cleaning of wool fabric has been of increasing interest due to availability and practicability. In this paper, two kinds of wool fabrics, including raw wool and Kroy-process wool fabric, were successfully modified by TiO₂/SiO₂ gel stabilized by 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid (CA), respectively. The optimum concentration of carboxylic acids and TiO₂/SiO₂ gel was decided by the crease recovery angles and total color difference (ΔE) values, respectively. The results revealed that wool fabrics treated with BTCA and TiO₂/SiO₂ had better wrinkle resistance in comparison with CA and TiO₂/SiO₂ treated samples. The decomposition of stains was studied using UV irradiation and the presence of TiO₂/SiO₂ gel demonstrated obvious self-cleaning property, in which the color of wool fabric was unchangeable. The hydrophilicity of Kroy-process wool fabric increased relative to raw ones. In addition, Scanning Electron Microscope images demonstrated the layer of TiO₂/SiO₂ nanoparticles coated on treated samples. In general, the adhesion properties coated to the fabric surface showed a slight loss even at harsh processing conditions, however, the anti-UV properties obviously increased due to the decrease in the fabric porosity. And the linkages between carboxylic acid and wool fibers were illustrated using FTIR pattern.     

SiO2 coated platy TiO2 designed for noble UV/IR-shielding materials

SiO₂ coated platy TiO₂ (S-pTi) was prepared as a noble UV/IR(Ultraviolet/Infrared)-shielding material by a modified Stöber method. S-pTi consists of a dense and uniform SiO₂ shell onto platy TiO₂ (pTi) core, and the thickness of SiO₂ shell layer was coated about 8–20 nm by tuning SiO₂ coating amount. The zeta-potential of S-pTi was decreased from −12 to −32 mV with increasing amounts of coated SiO₂, indicating the improvement of dispersibility between the particles. The UV-shielding ability of S-pTi was improved by enhancing UV absorption of the SiO₂ coating layer onto pTi and thus the photocatalytic activity was suppressed effectively. Compared to nanosized TiO₂(nTi), S-pTi showed higher UV absorption at the shorter wavelength and exhibited higher IR reflectance because of high reflective index and the crystal shape and size of pTi to reflect the IR effectively under its wide shielding area. These results can contribute to the prevention of harmful UV and the maintenance of a cool environment from IR heat source as noble UV/IR-shielding materials on the skin.     

Preparation and characterization of cerium‐doped titanium dioxide/ultrahigh‐molecular‐weight polyethylene porous composites with excellent photocatalytic activity

Porous ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐based composites filled with surface‐modified Ce‐doped TiO₂ nanoparticles (Ce–TiO₂/UHMWPE) were prepared by template dissolution. The composites were characterized by Fourier transform infrared spectroscopy, ultraviolet (UV)–visible spectroscopy, diffuse reflectance spectra, and scanning electron microscopy); the photocatalytic activity was also evaluated by the decomposition of methyl orange under UV exposure. The results demonstrate that the severe aggregation of Ce–TiO₂ nanoparticles could be reduced by surface modification via a silane coupling agent (KH570). The Ce–TiO₂/UHMWPE porous composites exhibited a uniform pore size. Doping with Ce⁴⁺ effectively extended the spectral response from the UV to the visible region and enhanced the surface hydroxyl groups of the TiO₂ attached to the matrix. With a degradation rate of 85.3%, the 1.5 vol % Ce–TiO₂/UHMWPE sample showed the best photocatalytic activity. The excellent permeability of the porous composites is encouraging for their possible use in wastewater treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Ultrasound assisted sol-gel TiO2 powders and thin films for photocatalytic removal of toxic pollutants

The paper presents a study on the structural, surface and photocatalytic properties of the ultrasound assisted sol-gel titanium dioxide particles, as part of stable photocatalytic ink formulations deposited on fabrics. The photocatalytic activity was validated using methylene blue as reference pollutant, under UV, VIS and combined UV+VIS radiation and allowed selecting the optimum TiO₂ samples for inks preparation. To minimize the particles agglomeration stabilizing agents were added and the stability was quantitatively evaluated considering the relative increase in the VIS transmittance for a pre-set period of 30 min. Further on, the ink(s) were deposited by cold spraying on cotton woven fabrics and a removal efficiency higher than 95% was observed in the degradation of the highly toxic mustard gas, after 30 min of UV irradiation.     

Imparting conductivity and chromic behavior on polyester fibers by means of poly(3‐methylthiophene) nanocoating

Poly(3‐methylthiophene) (P3MT)‐coated polyester fabric is a conductive textile with specific electrical and optical properties; for instance, color change under external stimulus (chromic behavior) was successfully prepared by chemical polymerization with continuous, speed stirring technique. To investigate the striking effect of some variable conditions of polymerization process, the effect of reaction time, temperature, and oxidant concentration on conductivity of the P3MT‐coated fabric was studied. Scanning electron microscopy confirmed that the surface of fabric has entirely been coated with P3MT particles. The further characterizations were investigated using Fourier transform infrared spectroscopy to provide evidence of forming particles onto the fabric, UV–vis absorption spectroscopy, electrical surface resistivity, and pressure dependence visible reflectance spectrophotometer measurements and X‐ray diffraction analysis. The blue shift in wavelength of maximum absorption of about 95 nm to a longer wavelength from that observed in the reflectance spectra of coated polyester fabric; under high‐pressure P3MT‐coated polyester fabric demonstrated piezochromism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Core‐shell ZrO2/PMMA composites via dispersion polymerization in supercritical fluid: Synthesis,characterization and mechanism

In this study, the polyester (PET) fabric was hydrolyzed with alkali to increase the surface activity and enhance the nano titanium dioxide (nano-TiO₂) adsorption to produce higher functionality. The PET fabric was first treated with sodium hydroxide along with cetyl trimethyl ammonium bromide as a cationic surfactant and then dipped into an ultrasound bath containing nano-TiO₂ followed by curing at high temperature. The weight loss, vertical wicking, and water droplet adsorption time were evaluated and are reported. The photocatalytic activity of TiO₂ nanoparticles deposited on the PET fabric was examined by the degradation of methylene blue as a model stain under daylight irradiation. The residual TiO₂ on the fabric surface after 1 and 10 successive washings was determined to indicate the washing durability of the finished fabric. Also, the UV protection was assessed by UV reflectance spectroscopy. The scanning electron microscopy pictures and energy-dispersive X-ray spectra of some fabrics are also reported. The surface hydrolysis of the PET fabric with sodium hydroxide created some voids and hydrophilic groups on the fabric surface; this led to the higher adsorption of nano-TiO₂ particles and enhanced the wettability, vertical wicking, and higher durability against repeated washings of the nano-TiO₂ treated fabric. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of TiO2‐Layer Thickness of Spray‐Coated Glass Beads on Their Photocatalytic Performance

TiO₂ is a suitable catalyst for potential photocatalytic processes, e.g., in wastewater treatment. For a technical realization of such processes, the application of immobilized TiO₂ in a continuous process would be desirable. However, since UV radiation has a limited penetration depth into a packed bed of pure TiO₂, supporting it on UV‐transparent glass beads offers the possibility to implement continuous photocatalytic processes in a fixed‐bed reactor. Considering this fact, glass beads were coated with TiO₂ powder in a fluidized‐bed reactor. The coated glass beads with varying TiO₂ layer thickness were tested in the photocatalytic degradation of methylene blue, and the influence of an addition of methyl cellulose during the coating process on the photocatalytic performance was investigated.     

Preparation of TiO2‐Coated Mo Powders for High Photocatalytic Property

An approach is introduced for fabricating the TiO₂‐coated molybdenum (Mo) powders via hydrothermal method, in which the Mo nanopowders were prepared by the electric explosion of wire method. The microstructure and photocatalytic properties of the samples were characterized by X‐ray diffraction, scanning electron microscopy, high‐resolution transmission electron microscopy, Raman spectroscopy (Raman), low temperature sorption of nitrogen (BET), and diffuse reflectance accessory of UV–Vis spectrophotometer. It was revealed that compared with pure TiO₂, the TiO₂‐coated Mo powders exhibited an improved photocatalytic activity, and the highest photocatalytic activity was achieved at the 1 wt% optimal mass percentage of the Mo nanopowders. The preparation of TiO₂‐coated Mo powders involved a relatively simple, economical, scalable, and also environment‐friendly approach.     

Durable UV-protective cotton fabric by deposition of multilayer TiO<Subscript>2</Subscript> nanoparticles films on the surface

Durable ultraviolet (UV)-protective cotton fabric has great application potential in outdoor cotton clothing. In this study, oppositely charged TiO₂ nanoparticles were deposited onto cotton fabric through the layer-by-layer self-assembly technique, resulting in multilayer films with UV-protective properties. The mechanism of the technology has been investigated through characterization of the structure and properties using different techniques including FTIR, UV–Vis spectroscopy, and a scanning electron microscope with an energy-dispersive X-ray spectrum. The results showed that TiO₂ nanoparticles distributed uniformly on the surface of cotton fibers. The TGA results indicated that the TiO₂ nanoparticles deposit on cotton fabrics had little effect on the thermal stability of cotton fabrics. The tensile strength and air permeability of the cotton samples were tested by a universal material testing machine and automatic ventilation instrument. The UV protection property of cotton fabric after assembled multilayer films was measured by an ultraviolet transmittance analyzer, and the laundering experiments were carried out to determine the durability of TiO₂ nanoparticles on cotton fabric. The results showed that the UV protection property of cotton fabrics after assembled TiO₂ nanoparticles was still maintained at a high level after five launderings.