Pianpanit Theerasarn, Saenboonruang Kiadtisak
Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
Specialized Center of Rubber and Polymer Materials in Agriculture and Industry (RPM), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
Gels. 2022 Mar 22;8(4):197. doi: 10.3390/gels8040197.
This work numerically determined high-energy photon shielding properties of self-healing poly(vinyl alcohol) (PVA) hydrogels containing lead-free, heavy-metal compounds, namely, bismuth oxide (BiO), tungsten oxide (WO), and barium sulfate (BaSO), through XCOM software packages. In order to understand the dependencies of the shielding properties of the hydrogels on filler contents and photon energies, the filler contents added to the hydrogels were varied from 0-40 wt.% and the photon energies were varied from 0.001-5 MeV. The results, which were verified for their reliability and correctness with those obtained from PHITS (Particle and Heavy Ion Transport code System), indicated that overall shielding performances, which included the mass attenuation coefficients (µ), the linear attenuation coefficient (µ), the half-value layer (HVL), and the lead equivalence (Pb), of the hydrogels improved with increasing filler contents but generally decreased with increasing photon energies. Among the three compounds investigated in this work, BiO/PVA hydrogels exhibited the highest photon attenuation capabilities, determined at the same filler content and photon energy, mainly due to its highest atomic number of Bi and the highest density of BiO in comparison with other elements and compounds. Furthermore, due to possible reduction in self-healing and mechanical properties of the hydrogels with excessive filler contents, the least content of fillers providing a 10-mm sample with the required Pb value of 0.5 mmPb was investigated. The determination revealed that only the hydrogel containing at least 36 wt.% of BiO exhibited the Pb values greater than 0.5 mmPb for all photon energies of 0.05, 0.08, and 0.1 MeV (common X-ray energies in general nuclear facilities). The overall outcomes of the work promisingly implied the potential of PVA hydrogels to be used as novel and potent X-ray and gamma shielding materials with the additional self-healing and nonlead properties.
这项工作通过XCOM软件包，以数值方式确定了含有无铅重金属化合物（即氧化铋（BiO）、氧化钨（WO）和硫酸钡（BaSO））的自愈合聚乙烯醇（PVA）水凝胶的高能光子屏蔽性能。为了了解水凝胶屏蔽性能对填料含量和光子能量的依赖性，添加到水凝胶中的填料含量在0-40 wt.%之间变化，光子能量在0.001-5 MeV之间变化。通过与PHITS（粒子和重离子传输代码系统）获得的结果进行可靠性和正确性验证，结果表明，水凝胶的整体屏蔽性能，包括质量衰减系数（µ）、线性衰减系数（µ）、半值层（HVL）和铅当量（Pb），随着填料含量的增加而提高，但通常随着光子能量的增加而降低。在这项工作中研究的三种化合物中，BiO/PVA水凝胶在相同的填料含量和光子能量下表现出最高的光子衰减能力，这主要是由于其Bi的原子序数最高，且与其他元素和化合物相比，BiO的密度最高。此外，由于过量填料含量可能会降低水凝胶的自愈合和机械性能，因此研究了为10毫米样品提供所需Pb值0.5 mmPb的最少填料含量。测定结果表明，只有含有至少36 wt.% BiO的水凝胶在0.05、0.08和0.1 MeV（一般核设施中常见的X射线能量）的所有光子能量下，其Pb值均大于0.5 mmPb。这项工作的总体成果有望表明PVA水凝胶具有作为新型高效X射线和γ射线屏蔽材料的潜力，同时还具有额外的自愈合和无铅特性。
