Papers by Keyword: Transparency

Abstract: The dust accumulation and dirt particles always degrade the transparency of glass, later hampers its various applications such as photovoltaic panels, building glass, and car-windshield. In this study, the hydrophilic self-cleaning coatings have been developed by using the nanocalcium Carbonate particles (nanoCaCO₃) and hydrophilic micro-titanium dioxide particles (µ-TiO₂). The presence of oxide groups, CO^-3 and TiO^2- forms a strong attraction of glass to polar water molecules. At the weight ratio of 1: 1 in the CaCO₃ to TiO₂ mixture, it forms a great hydrophilic property in which the water contact angle (WCA) of coated glass has been recorded as low as 11.46 ±0.85°. The coated glass also showed high transparency in UV and Visible regions. The optical transmission of coated glass was above 89% at the wavelength of 300-400nm and above 97% at the wavelength of 400-800nm. Due to its hydrophilic property, the coated glass is capable of removing the dust particles away via the water stream. The hydrophilic coating spontaneously forms the water-thin film after contact with coated glass without the presence of UV light.

Abstract: To meet the requirement for high transparency of agar gel used in tissue culture, bacteriological applications, and high-quality cosmetics and food, this study on improving the transparency of agar products was carried out by using activated carbon for decolorization and perlite for aiding filtration. The results showed that the pre-coating filtration method was better than that of the mixed slurry filtration, so an orthogonal experiment optimization was conducted using the pre-coating filtration method based on the single factor experimental results. The experimental results showed that the optimal process conditions based on the transparency index were: concentration of agar of 1.30%, activated carbon dosage of 0.80%, processing temperature of 95 °C, and treatment time of 20 min. Agar products with gel transparency of 58.93% and blue-ray whiteness value of 93.82 could be obtained under these experimental conditions. The order of the factors influencing the decolorization ratio of agar was as follows: activated carbon dosage > concentration of agar > processing temperature > treatment time. The experimental results provided effective procession methods for the production enterprises based on transparency and increased economic benefits, and it was of practical significance.

Abstract: The usage of biopolymers in developing biodegradable food packaging films that are sustainable and safe towards environment has been restricted because of the poor mechanical and barrier properties of the biopolymers. This study aims to enhance the limited properties of biopolymers particularly polylactic acid (PLA) for food packaging applications by investigating the effects of incorporating different types (montmorillonite (MMT) and halloysite) and concentrations (0–9 wt.%) of nanoclays on the mechanical, oxygen barrier, and transparency properties of the films. PLA with 3 wt.% concentration of nanoclays resulted in the optimum mechanical and oxygen barrier properties due to the strong interaction between nanoclays and torturous path length created by nanoclays respectively. Nevertheless, these properties reduced as more nanoclays (≥5 wt.%) was added into the films due to agglomeration of nanoclays. PLA incorporated with MMT nanoclay exhibited better properties compared to halloysite nanoclay due to the nanoclay structure in nature. Addition of 3 wt.% nanoclays into virtually transparent PLA film have only small effects on the transparency of the film whereby the reduction in light transmittance was only around 10%. This study is crucial to improve the feasibility of biopolymers usage for food packaging applications.

Abstract: Studying an influence of several parameters on Chemical Vapor Deposition (CVD) used for graphene synthesis is crucial to optimizing the graphene quality to be Compatible with advanced devices. The effect of different hydrogen (H₂) flow-rates (0, 50, 100, 150, 200, 250, and 300 sccm) during the pre-annealing process on CVD grown graphene have been reported. This study revealed that hydrogen flow rates during annealing changed the surface roughness/smoothness of the copper substrates. For high hydrogen flow rates, the smoothing effect was increased. Furthermore, the annealed graphene samples emerged a deferent number of layers because of morphological surface changes. According to Raman D- to G-band intensity ratios (I_D/I_G), the graphene quality was influenced by the annealing hydrogen flowrate. The visible light transmittance values of the grown graphene samples confirmed a few number of layers (mono to seven-layer). Mostly, the samples which annealed under moderate hydrogen flow rates showed less defects intensities and higher crystallite sizes.

Abstract: SrO-Al₂O₃ ceramics has prospective applications due to its photo-luminescence and persistent afterglow properties. Sr₃Al₂O₆-SrAl₂O₄ eutectic glass was prepared by using the aerodynamic levitator equipped with a CO₂ laser device. The prepared Sr₃Al₂O₆-SrAl₂O₄ eutectic glass beads were further heat-treated at temperature from 880°C to 980°C. The phase evolution, crystallization behavior, optical transmittance and mechanical properties of the annealed eutectic glass ceramics were investigated. The as-prepared glass is colorless and transparent over a wide range from ultraviolet to near-infrared region, and the average in-line transmittance is over 80% in the range of 260-3200nm. There were two crystal phases Sr₃Al₂O₆ and SrAl₂O₄ crystallized from the glass beads. With increasing heat-treatment temperature, the transparency of the samples decreased, and the hardness increased. The prepared Sr₃Al₂O₆-SrAl₂O₄ eutectic glass and glass ceramics may be a promising candidate for the development of photo-luminescence and persistent afterglow materials.

Abstract: Composites of a long-lasting phosphor, SrAl₂O₄:Eu,Dy, and glass were prepared by sintering the phosphor and glass powder. To enhance the afterglow luminescence, a borosilicate glass composition was chosen so that the refractive index of the glass matched that of the phosphor. Additional components with a high refractive index, such as La₂O₃ and Nb₂O₅, were added to the glass to increase the overall refractive index. As they tend to induce crystallization during sintering, small amounts of at least three types of such components were added to the glass to prevent crystallization. The surface of the composite was observed by a digital microscope with dark-field lighting. The phosphor particles became almost transparent because of the refractive-index matching, although bubbles were observed inside the phosphor particles. The afterglow luminance was, however, almost the same and the transmittance of the composite was not high because of many voids when compared to as that of the sample using the glass with a lower refractive index. The sample prepared under vacuum showed coloration and similar afterglow luminance even though the number of voids inside the composite decreased. To suppress the coloration, the amount of tin in the glass was increased, after which higher transparency and afterglow luminance were obtained. A 4-mm-thick sample showed a luminance of 118 mcd∙m^-2 60 min after irradiation by a D65 lamp with 200 lx for 20 min.

Abstract: Since the period of application curtain wall on skeleton buildings, small single–storey buildings are the great topic for architects. By various means architects have effort to create an impression of floating roof structure, or an illusion of levitating roof over the country. The effect of transparent space, overlapping interior and exterior, is possible to achieve by use of various structural schemes and materials of support structure. Nowadays single-storey transparent buildings are regarded as a phenomenon, which presents progress in architecture from the point of dematerialization of support structures and details of secondary transparent structures. Glass is in contemporary transparent curtain walls used not only as a material of the building skin, but also as the material of the support structure in various structural elements within hierarchy of the load bearing structure. Flat glass sheets forming the building skin could be within the suitable chosen shape of enclosed envelope also load bearing structure.

Abstract: Transparent bioceramics have great potential for applications in the biomedical field as they facilitate direct observation of the interactions at biomaterial – cell / tissue interfaces. Thus far, sintering of transparent hydroxyapatite (HA) usually involves application of extraordinarily high pressure and / or long duration. This study attempts to fabricate transparent HA by a direct and fast Spark Plasma Sintering (SPS) process using three different types of raw powder: micro-spheres (MS), nanorods (NR) and nanospheres (NS). The optical and mechanical properties of the sintered pellets were examined and compared. The highest total forward transmittance (TFT) showed by sintered MS pellet (~2 mm thick) was 85% in the visible spectrum, whereas sintered NR and NS pellets were either translucent or opaque. Although lowest degree of transparency was observed for NS pellets, they demonstrated highest Young’s modulus (E), hardness (H) and fracture toughness (K_IC). The eminent K_IC of NS pellets benefited mainly from its self-toughened microstructure.

Abstract: Colloidal processing was applied to a commercial 5 vol% 3Y-ZrO₂ nanosuspension with a particle size of 10-15 nm. The nanosuspension was concentrated by evaporation or by the newly developed method of osmotic dehydration. The viscosity and stability of concentrated suspensions were investigated. The concentrated nanosuspension prepared by osmotic dehydration was consolidated by centrifugation in non-porous moulds. The dried deposit had a relative density of 46% and pores ranged from 4 to 8 nm. This deposit was densified by pressureless presintering to closed porosity, followed by hot isostatic pressing in order to obtain transparent ceramics. After sintering, the tetragonal zirconia retained the nanocrystalline structure with an average grain size of 65 nm and an in-line transmission of 25 % (at 633 nm wavelength and 0.5 mm plate thickness).

Abstract: Transparency of glazed roofs does not depend on glass as material, which enables an admission of daylight to the interior, but it depends on the share of the glazed part of the canopy and their structural part. Spaces of glazed atria and courtyards of historical buildings are covered with very difficult shape of glazed canopies, which are supported by various types of load-bearing structures. In contemporary architecture glazed atria are used for the reason of saving energy and lighting up the inner spaces. New types of structures and using glass in load-bearing function in glass canopies are important thanks to their structural subtlety, where the structure covers slight part of glazed canopy. The result of clever ideas and modern technology are lightweight structures of bold forms and spans. In this context transparency became a new expression element of architecture.