Radiation shielding properties of silicon polymers

Fabrication, Structural Characterization, and Photon Attenuation Efficiency Investigation of Polymer-Based Composites

Experiments have assessed various polymer composites for radiation shielding in diverse applications. These composites are lighter and non-toxic when compared to lead (Pb), making them particularly effective in diagnostic imaging for shielding against low-energy photons. This study demonstrates the fabrication of four composites by combining a base material, specifically a high-density polyethylene (HDPE) polymer, with 10% and 20% silicon (Si) and silicon carbide (SiC), respectively. Additionally, 5% molybdenum (Mo) was incorporated into the composites as a heavy metal element. The composites obtained were fabricated into 20 disks with a uniform thickness of 2 mm each. Discs were exposed to radiation from a low-energy X-ray source (32.5-64.5 keV). The chemical and physical properties of composites were assessed. The shielding ability of samples was evaluated by determining the linear and mass attenuation coefficients (μ and μm), radiation protection efficiency (RPE), half-value layer (HVL), and mean free path (MFP). According to our findings, supplementing HDPE with additives improved the attenuation of beams. The μm values showed that composite X-ray shielding characteristics were enhanced with filler concentration for both Si and SiC. Polymer composites with micro-molecule fillers shelter X-rays better than polymers, especially at low energy. The HVL and MFB values of the filler are lower than those of the pure HDPE sample, indicating that less thickness is needed to shield at the appropriate energy. HC-20 blocked 92% of the incident beam at 32.5 keV. This study found that increasing the composite sample thickness or polymer filler percentage could shield against low-energy radiation.

X-ray/gamma radiation shielding properties of zinc ferrite nanoparticles synthesised via solution combustion method

Zinc ferrite (ZnFe2O4) nanoparticles were synthesised via solution combustion method using urea as a fuel. The synthesised samples were characterised with various techniques. The cubic structure with Fd-3 m space group is confirmed by Powder X-ray Diffraction and Bragg's reflection. The crystallite size estimated from Scherrer's method was found to be 40 nm. The agglomerated irregular shape and sized surface morphology was confirmed by Scanning Electron Microscopy image. The direct energy band gap determined from Wood and Tauc's relation was found to be 5.25 eV. Using a NaI (Tl) detector and multi-channel analyser, the described sample was examined for X-ray and gamma ray shielding characteristics in the energy range of 0.081-1.332 MeV. The measured shielding values are in good agreement with the theory, however below 356 keV, there is a little variation of up to 10%. The current work offers up new possibilities for using this simple, affordable, effective and low temperature approach to create nanomaterials for X-ray and gamma ray shielding.

Developing of Lead/Polyurethane Micro/Nano Composite for Nuclear Shielding Novel Supplies: γ-Spectroscopy and FLUKA Simulation Techniques

In this work, the effect of adding Pb nano/microparticles in polyurethane foams to improve thermo-physical and mechanical properties were investigated. Moreover, an attempt has been made to modify the micron-sized lead metal powder into nanostructured Pb powder using a high-energy ball mill. Two types of fillers were used, the first is Pb in micro scale and the second is Pb in nano scale. A lead/polyurethane nanocomposite is made using the in-situ polymerization process. The different characterization techniques describe the state of the dispersion of fillers in foam. The effects of these additions in the foam were evaluated, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) have all been used to analyze the morphology and dispersion of lead in polyurethane. The findings demonstrate that lead is uniformly distributed throughout the polyurethane matrix. The compression test demonstrates that the inclusion of lead weakens the compression strength of the nanocomposites in comparison to that of pure polyurethane. The TGA study shows that the enhanced thermal stability is a result of the inclusion of fillers, especially nanofillers. The shielding efficiency has been studied, MAC, LAC, HVL, MFP and Zeff were determined either experimentally or by Monte Carlo calculations. The nuclear radiation shielding properties were simulated by the FLUKA code for the photon energy range of 0.0001-100 MeV.

Nano tin oxide/dimethyl polysiloxane reinforced composite as a flexible radiation protecting material

Reinforced polymer composites are a recent type of advanced shielding material that has been studied experimentally and theoretically. This work described the protection properties of silicon rubber filled with nano and micro tin oxide (II). These shielding materials are evaluated by parameters such as mass attenuation coefficient, linear attenuation coefficient, mean free path, effective atomic number, and buildup factor. The morphology and mechanical properties of silicon rubber, which is reinforced with tin oxide (II) particles in terms of weight fraction and size, have been studied. The results explain that the mass attenuation coefficient increases as tin oxide (II) concentration increases at a particular photon energy. It was found that the shielding properties of nano tin oxide (II) composites are more effective than micro tin oxide (II) composites against gamma rays. The effective atomic number values increase by increasing tin oxide (II) and so on equivalent atomic number. On the other hand, increasing tin oxide (II) weight fraction led to an increase in buildup factor maximum, which proved that tin oxide (II) concentration has significant effectiveness in radiation protection.

Melanin protects Cryptococcus neoformans from spaceflight effects

As human activity in space continues to increase, understanding how biological assets respond to spaceflight conditions is becoming more important. Spaceflight conditions include exposure to ionizing radiation, microgravity, spacecraft vibrations and hypervelocity; all of which can affect the viability of biological organisms. Previous studies have shown that melanin-producing fungi are capable of surviving the vacuum of space and Mars-simulated conditions in Low Earth Orbit. This survival has been associated in part with the protective effects of melanin, but a comparison of fungal viability in the presence or absence of melanin following spaceflight has never been tested. In this study, we evaluated the protective effects of melanin by comparing the viability of melanized and non-melanized clones of Cryptococcus neoformans yeasts following a roundtrip to the International Space Station. Yeast colonies were placed inside two MixStix silicone tubes; one stayed on Earth and the other was transported inside for 29 days before returning to Earth. Post-flight analysis based on colony-forming unit numbers shows that melanized yeast viability was 50% higher than non-melanized yeasts, while no difference was observed between the Earth-bound control samples. The results suggest that fungal melanin could increase the lifespan of biological assets in space.

A Study on the Gamma Radiation Protection Effectiveness of Nano/Micro-MgO-Reinforced Novel Silicon Rubber for Medical Applications

In this work, we examined novel polymer composites for use in radiation protection applications. These prepared polymers are non-toxic compared with lead and show potential to be used as protective gear in different medical applications where low-energy photons are utilized. We prepared silicon rubber (SR) with different concentrations of micro- and nano-sized MgO. We used a HPGe detector to measure radiation attenuation factors at different photon energies, ranging from 59.6 to 1333 keV. We reported the effect of particle size on the attenuation parameters and found that the linear attenuation factors for SR with nano-MgO were higher than for SR with micro-MgO. The mean free path (MFP) for pure SR and SR with micro- and nano-sized MgO were determined, and we found that silicon rubber with MgO (both micro- and nano-sized) has a lower MFP than pure SR. The linear attenuation coefficient results show the importance of using SR with high MgO content for low-energy radiation protection applications. Moreover, the half-value layer (HVL) results demonstrate that we need a certain thickness of SR with nano-MgO to effectively reduce the intensity of the low-energy photons.

Silicone rubber composite reinforced by bismuth tungsten oxide as an effective gamma ray protective materials

The workers’ continual exposure to nuclear radiation makes it indispensable to invent and form lightweight materials as flexible radiation shields. So, in this article, silicone rubber SR inlaid with varying filler ratios of bismuth tungsten oxide Bi2(WO4)3 was produced. Mechanical properties, hardness, tensile strength, tensile modulus, and elongation at break, of the SR/Bi2(WO4)3 composites were studied as a function of filler concentration and irradiation dose. The Bi2(WO4)3 filler enhanced these properties. On the other hand, with augmentation of irradiation dose, hardness of the SR/Bi2(WO4)3 composites increased and the other mechanical properties decreased. Under accurate geometry conditions, the gamma ray attenuation coefficients of the SR/Bi2(WO4)3 composites were studied at the energies 661.66, 1173.24, and 1332.5 keV. The attenuation parameters, linear attenuation coefficients $$\mu$$ μ , experimental mass attenuation coefficients $${\sigma }_{exp.}$$ σ e x p . , and half value layer HVL results revealed that the attenuation ability of the composite was enhanced with the increase of Bi2(WO4)3 concentration. The results of $${\sigma }_{exp.}$$ σ e x p . were confirmed through their congruence with the theoretical calculations of mass attenuation coefficients $${\sigma }_{theo.}$$ σ t h e o . Considering the merits of lightweight, high mechanical properties, superior attenuation ability, and appropriate irradiation resistance, the produced SR/Bi2(WO4)3 composite is suitable as durable and flexible gamma ray shields such as anti-radiation coats, gloves, shoes.

Are Metal Halide Perovskite Solar Cells Ready for Space Applications?

The appeal of metal halide perovskite solar cells (PSCs) has been widely demonstrated in the field of photovoltaic technology. On account of the excellent optical and electrical properties, as well as compatibility with flexible substrates, the PSCs also hold the highest record of specific power for lightweight solar cell devices, suggesting excellent promise in space applications. Hence, there is increasing interest in the performance of PSCs in space environments where radiation beams and thermal cycling can cause extreme stress on the devices. In this Perspective, we provide a brief summary of the research on PSCs for space applications. The radiation tolerance and thermal stability of PSCs and the fundamental mechanisms are discussed and analyzed. Key challenges facing PSC technology toward future space applications are demonstrated. This Perspective features the prospect of PSCs as the next frontier in space PV technology.

The Influence of Bi2O3 Nanoparticle Content on the γ-ray Interaction Parameters of Silicon Rubber

In this study, synthetic silicone rubber (SR) and Bi₂O₃ micro- and nanoparticles were purchased. The percentages for both sizes of Bi₂O₃ were 10, 20 and 30 wt% as fillers. The morphological, mechanical and shielding properties were determined for all the prepared samples. The Linear Attenuation Coefficient (LAC) values of the silicon rubber (SR) without Bi₂O₃ and with 5, 10, 30 and 30% Bi₂O₃ (in micro and nano sizes) were experimentally measured using different radioactive point sources in the energy range varying from 0.06 to 1.333 MeV. Additionally, we theoretically calculated the LAC for SR with micro-Bi₂O₃ using XCOM software. A good agreement was noticed between the two methods. The NaI (Tl) scintillation detector and four radioactive point sources (Am-241, Ba-133, Cs-137 and Co-60) were used in the measurements. Other shielding parameters were calculated for the prepared samples, such as the Half Value Layer (HVL), Mean Free Path (MFP) and Radiation Protection Efficiency (RPE), all of which proved that adding nano-Bi₂O₃ ratios of SR produces higher shielding efficiency than its micro counterpart.

Optical and radiation shielding characteristics of tellurite glass doped with different rare-earth oxides

Shielding glass materials doped with heavy metal oxides show an improvement in the effectiveness of the materials used in radiation shielding. In this work, the photon shielding parameters of six tellurite glass systems doped with several metal oxides namely, 70TeO2-10P2O5- 10ZnO- 5.0PbF2- 0.0024Er2O3- 5.0X (where X represents different doped metail oxides namely, Nb2O5, TiO2, WO3, PbO, Bi2O3, and CdO) in a broad energy spectrum, ranging from 0.015 MeV to 15 MeV, were evaluated. The shielding parameters were calculated using the online software Phy-X/PSD. The highest linear and mass attenuation coefficients recorded were obtaibed from the samples containing bismuth oxide (Bi2O3), and the lowest half-value layer and mean free path were recorded among the other samples. Furthermore, the shielding effectiveness of tellurite glass systems was compared with commercial shielding materials (RS-369, RS-253 G18, chromite, ferrite, magnetite, and barite). The optical parameters viz, dispersion energy, single-oscillator energy, molar refraction, electronic polarizability, non-linear refractive indices, n2, and third-order susceptibility were measured and reported at a different wavelength. Bi2O3 has a strong effect on enhancing the optical and shielding properties. The outcome of this study suggests the potential of using the proposed glass samples as radiation-shielding materials for a broad range of imaging and therapeutic applications.

Determination of radioprotective and genotoxic properties of sulfamide derivatives

Some potential drug active substances with the ability to reduce the effects of radiation on human tissues and cells were investigated. For this purpose, eight different types of sulfamide derivatives were synthesized and nuclear radiation protection parameters were determined. Neutron radiation reduction parameters such as the half-value layer effective removal cross-sections, mean free path, and the number of particles passing through the sample were determined with GEANT4 code. Additionally, the gamma radiation attenuation parameters of the materials examined were determined using Phy-X/PSD software in the energy area of 0.015–15 MeV. These parameters are the half-value layer, mass attenuation coefficient, mean free path, exposure buildup factor and effective atomic number. Neutron radiation absorption experiments were applied using an 241Am-Be fast neutron source. All results obtained for neutron radiation were compared with paraffin and water. It has been found that the ability of sulfamide derivatives to absorb these radiations is superior to reference materials. To determine whether these derivatives could have adverse effects on human health, their genotoxic potential was determined using the Ames/Salmonella bacterial reversion test. The results showed that these derivatives can be considered genotoxically safe in tests at concentrations up to 5 mM. Thus, it is suggested that the derivative materials examined in this study can be used as active substances for a drug to be made for protection against both neutron and gamma radiation.

A Brief Review on the High-Energy Electromagnetic Radiation-Shielding Materials Based on Polymer Nanocomposites

This paper revises the use of polymer nanocomposites to attenuate high-energy electromagnetic radiation (HE-EMR), such as gamma radiation. As known, high-energy radiation produces drastic damage not only in facilities or electronic devices but also to life and the environment. Among the different approaches to attenuate the HE-EMR, we consider the use of compounds with a high atomic number (Z), such as lead, but as known, lead is toxic. Therefore, different works have considered low-toxicity post-transitional metal-based compounds, such as bismuth. Additionally, nanosized particles have shown higher performance to attenuate HE-EMR than those that are micro-sized. On the other hand, materials with π-conjugated systems can also play a role in spreading the energy of electrons ejected as a consequence of the interaction of HE-EMR with matter, preventing the ionization and bond scission of polymers. The different effects produced by the interactions of the matter with HE-EMR are revised. The increase of the shielding properties of lightweight, flexible, and versatile materials such as polymer-based materials can be a contribution for developing technologies to obtain more efficient materials for preventing the damage produced for the HE-EMR in different industries where it is found.

Gamma Ray Shielding Properties of Yb3+-Doped Calcium Borotellurite Glasses

This research work aims to investigate the radiation shielding ability of a Yb3+-doped calcium borotellurite glass system. The system has the basic composition of CaF2–CaO–B2O3–TeO2–Yb2O3 but is denoted as TeBYbn for simplicity. The effect of increasing the TeO2 content in the glasses from 10 to 54 mol% was investigated, with five different chosen compositions and densities. The Phy-X/PSD program was used to investigate the mass attenuation coefficient (µ/ρ) of the samples. The mass attenuation coefficients were theoretically determined by using an online software for the calculation of shielding parameters. Other parameters were then calculated and analyzed, such as the linear attenuation coefficient (µ), transmission factor (TF), radiation protection efficiency (RPE), effective atomic number (Zeff), and mean free path (MFP). TeBYb5, the glass with the greatest TeO2 content, was shown to have the greatest µ/ρ; however, at greater energies, the differences between the values are practically negligible. µ was shown to increase with density, such as from 0.386 cm−1 to 0.687 cm−1 for TeBYb1 and TeBYb5 at 0.284 MeV, respectively. The least TF was found for samples with a thickness of 1.5 cm, proving an inverse correlation between the thickness of the sample and the TF. The HVL and TVL of the glasses decreased as the density of the samples increased, which means that TeBYb1 is the least effective out of the investigated glasses. The five samples proved to have a lower MFP than some other shielding glasses, demonstrating their capabilities as radiation shields. Based on the calculated parameters, TeBYb5 indicated the greatest photon attenuation ability.

Detailed Inspection of γ-ray, Fast and Thermal Neutrons Shielding Competence of Calcium Oxide or Strontium Oxide Comprising Bismuth Borate Glasses

For both the B₂O₃-Bi₂O₃-CaO and B₂O₃-Bi₂O₃-SrO glass systems, γ-ray and neutron attenuation qualities were evaluated. Utilizing the Phy-X/PSD program, within the 0.015–15 MeV energy range, linear attenuation coefficients (µ) and mass attenuation coefficients (μ/ρ) were calculated, and the attained μ/ρ quantities match well with respective simulation results computed by MCNPX, Geant4, and Penelope codes. Instead of B₂O₃/CaO or B₂O₃/SrO, the Bi₂O₃ addition causes improved γ-ray shielding competence, i.e., rise in effective atomic number (Z_eff) and a fall in half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). Exposure buildup factors (EBFs) and energy absorption buildup factors (EABFs) were derived using a geometric progression (G–P) fitting approach at 1–40 mfp penetration depths (PDs), within the 0.015–15 MeV range. Computed radiation protection efficiency (RPE) values confirm their excellent capacity for lower energy photons shielding. Comparably greater density (7.59 g/cm³), larger μ, μ/ρ, Z_eff, equivalent atomic number (Z_eq), and RPE, with the lowest HVL, TVL, MFP, EBFs, and EABFs derived for 30B₂O₃-60Bi₂O₃-10SrO (mol%) glass suggest it as an excellent γ-ray attenuator. Additionally, 30B₂O₃-60Bi₂O₃-10SrO (mol%) glass holds a commensurably bigger macroscopic removal cross-section for fast neutrons (Σ_R) (=0.1199 cm⁻¹), obtained by applying Phy-X/PSD for fast neutrons shielding, owing to the presence of larger wt% of ‘Bi’ (80.6813 wt%) and moderate ‘B’ (2.0869 wt%) elements in it. 70B₂O₃-5Bi₂O₃-25CaO (mol%) sample (B: 17.5887 wt%, Bi: 24.2855 wt%, Ca: 11.6436 wt%, and O: 46.4821 wt%) shows high potentiality for thermal or slow neutrons and intermediate energy neutrons capture or absorption due to comprised high wt% of ‘B’ element in it.

Polymeric composite materials for radiation shielding: a review

The rising use of radioactive elements is increasing radioactive pollution and calling for advanced materials to protect individuals. For instance, polymers are promising due to their mechanical, electrical, thermal, and multifunctional properties. Moreover, composites made of polymers and high atomic number fillers should allow to obtain material with low-weight, good flexibility, and good processability. Here we review the synthesis of polymer materials for radiation protection, with focus on the role of the nanofillers. We discuss the effectivness of polymeric materials for the absorption of fast neutrons. We also present the recycling of polymers into composites.