Lead Free Multilayered Polymer Composites for Radiation Shielding

A study on the mechanical and radiation shielding characteristics of concrete samples reinforced with brass alloy and boron carbide

In this study, the gamma radiation shielding properties of concrete samples reinforced with 10%, 20%, 30%, 40% and 50% of the cement weight of brass alloy were investigated. To test gamma shielding performance of the samples, mass and linear attenuation coefficients, half and tenth value layers, effective atomic number and radiation protection efficiency parameters were determined experimentally, theoretically and Monte Carlo simulations (GEANT4 and FLUKA). The studies were performed at 11 different gamma energies that range from 59.5 to 1332.5 keV emitted from 22Na, 60Co, 133Ba, 137Cs and 241Am radioactive sources. The obtained results showed that the gamma shielding property of the samples increases with increasing brass alloy amount, and the sample reinforced with 50% brass alloy was the most effective one to shield gamma radiation. Neutron shielding properties of the sample reinforced with 50% brass alloy were therefore investigated by adding 5%, 10%, 15% and 20% boron carbide (B4C). The neutron permeability, which is an important parameter in terms of the neutron shielding performance of B4C added concrete samples, was investigated by using GEANT4 and FLUKA simulation programs. While the total macroscopic cross section results obtained with GEANT4 for concretes coded as P0, P50, P50B5, P50B10, P50B15 and P50B20 are 2.0290, 2.0324, 2.0343, 2.0346, 2.0361 and 2.0367 cm-1, respectively, the results obtained with FLUKA are 2.0287, 2.0322, 2.0337, 2.0342, 2.0357 and 2.0362 cm-1, respectively. Therefore, the sample containing 20% B4C is the sample that best shields neutron radiation. In addition to the radiation shielding properties of the produced samples, the mechanical properties such as compressive strength, Schmidt surface hardness, ultrasound pulse velocity were also tested in terms of usability.

[Evaluation of Transmitted X-ray Spectrum, Lead Equivalent, and Uniformity of Radiation Protective Clothing Made of Lead-containing and Lead-free Materials]

PURPOSE

The purpose of this study was to evaluate the protective performance of several new radiation-protective clothing and to clarify issues of quality control.

METHODS

The composition of the shielding elements was analyzed using X-ray fluorescence analysis, and the energy spectrum of transmitted X-rays was measured. Furthermore, the lead equivalent and uniformity were measured from the transmitted X-ray doses according to Japanese industrial standards (JIS). Uniformity was evaluated by transmitting X-ray images of each radiation protective clothing in addition to the conventional method.

RESULTS

The energy spectrum showed K-absorption edges of lead, bismuth, tin, etc., which were detected in the composition analysis. The multi-layered protective material maintained higher shielding ability at high tube voltages. In addition, X-ray images of the radiation-protective clothing showed uneven density and dots, and the differences in uniformity measurement methods and points that didn't meet the required shielding capacity were seen.

CONCLUSION

The current JIS does not allow accurate evaluation of the lead equivalent and uniformity, so visual evaluation of X-ray images is important. It is necessary to establish standardized standards for quality control performed by each facility.

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.

Synthesis and characterisation of lead-magnesium-boron nanocomposite for radiation shielding application

There is a need for the replacement of toxic lead with nontoxic materials in radiation shielding applications. Instead of pure lead, lead mixed compounds/mixtures/alloys are considered to be less toxic and hence preferred for radiation shielding purposes. The compounds with magnesium are said to be having good magnetic and mechanical properties. Meanwhile, the boron element avoids secondary radiation and absorbs neutrons. The compound which is a mixture of lead, magnesium and boron is expected to be a good shielding material for radiation for X-rays/gamma rays. Hence in the present study, we have synthesised the lead-magnesium-boron (LMB) nanocomposites (NCs) using the green synthesis approach for the first time. LMB is synthesised by solution combustion method using Aloe vera as a reducing agent. The synthesised NCs are characterised using well-known characterisation techniques. Powder X-ray diffraction confirmed the formation of multi-phase LMB NCs, and average crystal size is found to be 13-15 nm. Surface morphology and chemical composition are affirmed by SEM and EDX. The optical energy gap is found to be 1.87 eV. FTIR confirmed the functional groups. X-rays/gamma rays, neutrons and bremsstrahlung radiation shielding efficiency are measured by experimental and theoretical, compared with conventional shielding materials. LMB NCs have proved to be efficient. Hence, LMB NCs proved to be potential in X-rays/gamma rays, neutrons and bremsstrahlung radiation shielding.

Development of Lead-Free Radiation Shielding Material Utilizing Barium Sulfate and Magnesium Oxide as Fillers in Addition Cure Liquid Silicone Rubber

The radiological protection has the purpose of safeguarding the physical well-being of the user, preventing exposure to detrimental levels of ionizing radiation. This study introduces a novel, cost-effective category of lead-free elastomeric material designed for radiation shielding. The filler compounds utilized are notably lighter than conventional lead-based materials, enhancing user ergonomics during application. They comprise of a blend of barium sulfate combined or not with magnesium oxide with addition-cure liquid silicone rubber. To ensure the effectiveness of the radiation shielding, X-ray transmission measurements were performed for the different thicknesses of the materials and the results compared with Monte Carlo simulations. Additionally, the physical properties of the new materials, such as density, homogeneity, tensile strength, viscosity, and wettability, were also evaluated. The findings indicate that both materials fulfill the requirement for application in radiation protection garments.

Modification of 3D Printable Polymer Filaments for Radiation Shielding Applications

There is a growing need to develop lead-free shielding materials that are safe, low weight, durable, environmentally friendly, chemically and mechanically stable and customizable for specific applications. Fused deposition modeling (FDM), an additive manufacturing technique based on the extrusion of a thermoplastic filament into a 3D printed object one layer at a time, could be employed well in applications involving ionizing radiation due to its relatively low cost, design flexibility and high manufacturing precision. This study aimed at developing 3D printing composites that contain Titanium dioxide as a filler agent for shielding in a medical radiation environment. First, the effect of low-dose ionizing radiation (up to 15 Gy) on the mechanical properties of common 3D printing polymers, ABS, ULTRAT, PLA, NYLON, ASA and PETG, was investigated. Since ABS experienced the lowest variation in its ultimate tensile strength (±5%) and Young’s modulus (−5%/+11%), it was chosen as a matrix for a new extruded 3D filament containing TiO2 at 1 wt.%, 3 wt.%, and 5 wt.%. With the incorporation of TiO2 at different filler contents, the UTS of the ABS composites varied between 24.1 MPa and 28.4 MPa, with the highest value recorded for 3 wt.% TiO2. Young’s modulus values were dependent on both the TiO2 concentration and on the irradiation dose. In addition, the ABS/TiO2 composites with a higher filler content (3 wt.% and 5 wt.%) maintained their attenuation ability even after exposure to a radiation dose of 100 Gy as opposed to pure ABS, which exhibited a ~2.5% reduction in its mass attenuation coefficient after exposure to the same dose of radiation. The pilot investigation performed demonstrated that the newly developed ABS/TiO2 composite containing 5 wt.% of filler can be successfully employed to shield electronic devices operating in a radiotherapy room.

Investigation of the Effect of PbO Doping on Telluride Glass Ceramics as a Potential Material for Gamma Radiation Shielding

The purpose of this paper is to study the effect of PbO doping of multicomponent composite glass-like ceramics based on TeO₂, WO₃, Bi₂O₃, MoO₃, and SiO₂, which are one of the promising materials for gamma radiation shielding. According to X-ray diffraction data, it was found that the PbO dopant concentration increase from 0.10 to 0.20-0.25 mol results in the initialization of the phase transformation and structural ordering processes, which are expressed in the formation of SiO₂ and PbWO₄ phases, and the crystallinity degree growth. An analysis of the optical properties showed that a change in the ratio of the contributions of the amorphous and ordered fractions leads to the optical density increase and the band gap alteration, as well as a variation in the optical characteristics. During the study of the strength and mechanical properties of the synthesized ceramics, depending on the dopant concentration, it was found that when inclusions in the form of PbWO₄ are formed in the structure, the strength characteristics increase by 70-80% compared to the initial data, which indicates the doping efficiency and a rise in the mechanical strength of ceramics to external influences. During evaluation of the shielding protective characteristics of the synthesized ceramics, it was revealed that the formation of PbWO₄ in the structure results in a rise in the high-energy gamma ray absorption efficiency.

Influence of Parameters and Performance Evaluation of 3D-Printed Tungsten Mixed Filament Shields

Currently, protective clothing used in clinical field is the most representative example of efforts to reduce radiation exposure to radiation workers. However, lead is classified as a substance harmful to the human body that can cause lead poisoning. Therefore, research on the development of lead-free radiation shielding bodies is being conducted. In this study, the shielding body was manufactured by changing the size, layer, and height of the nozzle, using a 90.7% pure tungsten filament, a 3D printer material, and we compared its performance with existing protection tools. Our findings revealed that the shielding rate of the mixed tungsten filament was higher than that of the existing protective tools, confirming its potency to replace lead as the most protective material in clinical field.

Investigation of the Efficiency of Shielding Gamma and Electron Radiation Using Glasses Based on TeO2-WO3-Bi2O3-MoO3-SiO to Protect Electronic Circuits from the Negative Effects of Ionizing Radiation

This article considers the effect of MoO₃ and SiO additives in telluride glasses on the shielding characteristics and protection of electronic microcircuits operating under conditions of increased radiation background or cosmic radiation. MoO₃ and SiO dopants were chosen because their properties, including their insulating characteristics, make it possible to avoid breakdown processes caused by radiation damage. The relevance of the study consists in the proposed method of using protective glasses to protect the most important components of electronic circuits from the negative effects of ionizing radiation, which can cause failures or lead to destabilization of the electronics. Evaluation of the shielding efficiency of gamma and electron radiation was carried out using a standard method for determining the change in the threshold voltage (∆U) value of microcircuits placed behind the shield and subjected to irradiation with various doses. It was established that an increase in the content of MoO₃ and SiO in the glass structure led to an increase of up to 90% in the gamma radiation shielding efficiency, while maintaining the stability of microcircuit performance under prolonged exposure to ionizing radiation. The results obtained allow us to conclude that the use of protective glasses based on TeO₂-WO₃-Bi₂O₃-MoO₃-SiO is highly promising for creating local protection for the main components of microcircuits and semiconductor devices operating under conditions of increased background radiation or cosmic radiation.

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.

Preparation and Performance Evaluation of X-ray-Shielding Barium Sulfate Film for Medical Diagnosis Using PET Recycling and Multi-Carrier Principles

The use of disposable containers and packaging materials has increased due to the recent COVID-19 pandemic. Thus, the generation of plastic waste is also increasing, and research on recycling such waste is being actively conducted. In this study, an X-ray-shielding film for medical diagnosis was manufactured by mixing a radiation-shielding material and a plastic waste-based polymer material and its effectiveness was evaluated. The film, which is intended as a fabric for a shielding garment, consists of barium sulfate (BaSO4) shielding nanoparticles embedded in a matrix of polyethylene terephthalate (PET), a commonly available waste plastic material. A particle-dispersing technology, which can improve the ratio between the shielding and matrix materials while maintaining the tensile strength of the film, was studied. Therefore, to increase the content of the barium sulfate (BaSO4) nanoparticles used as the shielding material, this multi-carrier method—under which the particles are dispersed in units of time—was developed to improve the shielding performance. Compared with the effectiveness of lead (Pb) shielding film, the 3 mm barium sulfate film developed in this study satisfies the lead equivalent of 0.150 mmPb when stacked in two layers. Therefore, a shielding film was successfully manufactured by using plastic waste as a polymer resin and barium sulfate, an eco-friendly radiation-shielding material, instead of lead.