Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications.
The present investigation aims at developing a reinforced polymer composite to be used in electronic applications (for/as high-speed data transforming insulator material). Poultry feather reinforced composite is prepared varying the reinforcement of chicken feather fibrils (i.e., with 10%, 20%, and 30% weight fraction) using epoxy resin as matrix material. The dielectric properties of the composites are evaluated at different temperature and frequency ranges. It is found that the dielectric properties are dependent on operating frequency and temperature conditions. Such composites have potential use as a low dielectric material for typical applications. Flexural strength, microhardness, and density of this chicken feather composite are also evaluated. Microscopic observation of the feather is made with scanning electron microscope.
Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution.
An efficient way through borohydride synthesis route using NaBH 4 was performed to prepare pure zirconia nanopowders via three different conditions such as gelation, precipitation, and constant pH. Zirconia powders prepared through constant pH route show highest activation energy of crystallization (E a = 260 kJ/mol) or higher exothermic peak temperature (717°C), when compared with gelation or precipitation route due to its controlled growth of smaller crystallites. The released huge amount of H 2 gas bubbles during borohydride synthesis via constant pH route play a major role for formation of loose smaller crystallites and thus enhances the activation energy of crystallization of pure zirconia. So, the as-prepared zirconia powders prepared through constant pH route remain amorphous up to 600°C and pure t-ZrO 2 (~20 nm) was stable up to 800°C.
The improved performance of polymers and their composites in industrial and structural applications by the addition of particulate fillers has shown a great promise and so has lately been the subject of considerable interest. In the present study, titanium oxide (TiO 2 ) particles of average size 75 μm are reinforced in unsaturated polyester resin to prepare particulate filled composites of three different compositions (with 0, 10, and 20 wt% of TiO 2 ). Dry sliding wear trials are conducted following design of experiments (DOE) using a standard pin-on-disc test set-up. Significant control factors predominantly influencing the wear rate are identified. Effect of TiO 2 content on the wear rate of polyester composites under different test conditions is studied. An Artificial Neural Networks (ANN) approach taking into account training and test procedure to predict the dependence of wear behavior on various control factors is implemented. This technique helps in saving time and resources for large number of experimental trials and predicts the wear response of TiO 2 -polyester composites beyond the experimental domain.
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