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Summary Composite materials that contain thermally and chemically stable boron compounds are attractive candidates for applications that require high neutron absorption due to the large neutron absorption cross‐section of boron. Electrospun polymer nanofibers have a unique volume‐to‐surface area, incorporating carbon and hydrogen atoms in their molecular structure that could moderate and thermalize incident neutrons. Nonwoven nanofibers could in turn reduce neutron scattering and increase neutron absorption by providing large surfaces and better atom economy in the shield materials. The expected high absorption will result from improved neutron interaction with high neutron absorbance hydrogen, carbon, and boron atoms in the nanofibers through increased specific surface area and atom economy. In this work, elemental boron‐doped PVA polymeric nanofibers are produced for the first time to date for the application of neutron shielding. With the increasing demand for nuclear power generation and radiation therapies in medicine, the need for producing lightweight and flexible materials that could replace the traditional heavy metal/metal carbide‐based shields is vital. Similarly, the need for flexible materials that could shield neutrons is also becoming critical for aerospace applications. The effect of boron content on the quality of fibers and neutron shielding capacity is evaluated by using an Am‐Be neutron source. Characterization studies of produced nanofibers were carried out by SEM, TGA, FT‐IR, and XPS analyses. Results have shown that PVA‐based nanofibers doped with wt% 0.1 to 0.5 boron, having fiber diameter distribution between 60 and 330 nm range, could absorb up to 6% of neutron flux.

In this manuscript, a borate ester solution, as a precursor, is prepared by combining polyvinyl alcohol (PVA) and boric acid (BA). The precursor is then electrospun to form nanofibers. However, the addition of BA has a negative effect on the spinning behavior by changing the conductivity. The solution's quality is enhanced through use of additives such as glycerol, sodium chloride, and acetic acid. The effect of additives on the viscosity and conductivity of solutions, and their spinning behavior, is investigated. By adjusting electrospinning process variables and solution properties, nanofibers are produced. Fourier transform infrared (FT‐IR) analysis is performed to identify the formation of borate ester as a result of the reaction between PVA and BA. Thermal analysis is used to characterize the thermal stability of the fibers. Scanning electron microscopy (SEM) is used to examine the fiber morphology and diameter distribution. The findings are used to determine the best viscosity–conductivity windows for the production of electrospun borate ester nanofibers. Finally, the ability of optimized nanofibers to capture neutrons is evaluated using an Am‐Be neutron source and a BF3 detector set up. The results of the measurements indicate that the incorporation of BA into PVA nanofibers can enhance their neutron shielding capabilities up to 7.3%.

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In this study, 1 wt% boron carbide (B4C) reinforced PVA nanofibers were fabricated by the electrospinning technique as a new generation of ultra‐thin, lightweight, and flexible neutron shielding nanocomposites. The influence of B4C particles' size and morphology on the fiber formation and radiation shielding performance of fiber mats was investigated. The results indicate that the particle characteristics have a dramatic influence on the formation and properties of nanocomposites. The thicknesses of individual fibers reinforced with sol–gel synthesized nano‐sized boron carbide particles were in the range of 50–250 nm, while those containing commercial B4C powder were produced in the thickness range of 1–2 μm. In contrast to the commercial particles, the sol–gel synthesized nano B4C particles enhanced the fiber mat's density and the roundness of individual fibers. Both theoretical and experimental radiation shielding studies showed that B4C reinforcement successfully improved the neutron and gamma attenuation of the neat PVA matrix. Furthermore, it was found that a 6.5 mm thick PVA nanofiber mat, reinforced with only 1 wt% B4C nanoparticles shielded up to about 7.4% of the initial neutron flux. Compared to the neat PVA fiber mat, reinforcement of PVA fibers with 1 wt% sol–gel synthesized nano‐sized boron carbide particles enhanced the neutron shielding by 50.31%. Moreover, even though B4C is not an effective gamma shielding reinforcement, the amplified density of nanocomposite fiber mats also enhanced gamma attenuation.

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