Toyen Donruedee, Wimolmala Ekachai, Saenboonruang Kiadtisak
Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
Special Research Unit of Radiation Technology for Advanced Materials (RTAM), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
Polymers (Basel). 2023 Jun 17;15(12):2717. doi: 10.3390/polym15122717.
Due to rapid increases in the utilization of radiation and nuclear technologies, effective and suitable radiation-shielding materials have become one of the most sought-after options to protect users and the public from excessive exposure to the radiation. However, most radiation-shielding materials have greatly reduced mechanical properties after the addition of fillers, resulting in their limited useability and shortened lifetime. Therefore, this work aimed to alleviate such drawbacks/limitations by exploring a possible method to simultaneously enhance both the X-ray shielding and mechanical properties of bismuth oxide (BiO)/natural rubber (NR) composites through multi-layered structures, with varying (1-5) layers and a total combined thickness of 10 mm. To correctly determine the effects of the multi-layered structures on the properties of NR composites, the formulation and layer configuration for all multi-layered samples were tailored such that their theoretical X-ray shielding properties were equal to those of a single-layered sample that contained 200 phr BiO. The results indicated that the multi-layered BiO/NR composites with neat NR sheets on both outer layers (sample-D, sample-F, sample-H, and sample-I) had noticeably higher tensile strength and elongation at break than those of the other designs. Furthermore, all multi-layered samples (sample-B to sample-I), regardless of the layer structure, had enhanced X-ray shielding properties compared to those with a single layer (sample-A), as shown by their higher values of the linear attenuation coefficient (µ) and lead equivalence (Pb) and the lower value of the half-value layer (HVL) in the former. This work also determined the effects of thermal aging on relevant properties for all samples, with the results revealing that all the thermal-aged composites had higher values for the tensile modulus but lower values for the swelling percentage, tensile strength, and elongation at break, compared with the non-aged composites. Hence, based on the overall outcomes from this work, it could be concluded that the worrisome decreases in mechanical properties of the common single-layered NR composites after the addition of BiO could be prevented/reduced by introducing appropriate multi-layered structures, which would not only widen potential applications but also prolong the lifetime of the composites.
由于辐射和核技术的使用迅速增加，有效且合适的辐射屏蔽材料已成为保护使用者和公众免受过度辐射暴露的最热门选择之一。然而，大多数辐射屏蔽材料在添加填料后机械性能大幅下降，导致其使用性受限且寿命缩短。因此，本研究旨在通过探索一种可能的方法来缓解这些缺点/限制，即通过多层结构同时提高氧化铋（BiO）/天然橡胶（NR）复合材料的X射线屏蔽性能和机械性能，层数为1 - 5层，总组合厚度为10毫米。为了正确确定多层结构对NR复合材料性能的影响，对所有多层样品的配方和层配置进行了调整，使其理论X射线屏蔽性能与含有200份BiO的单层样品相同。结果表明，外层均为纯NR片材的多层BiO/NR复合材料（样品D、样品F、样品H和样品I）的拉伸强度和断裂伸长率明显高于其他设计。此外，所有多层样品（样品B至样品I），无论层结构如何，与单层样品（样品A）相比，其X射线屏蔽性能均有所增强，表现为前者的线性衰减系数（µ）和铅当量（Pb）值更高，半值层（HVL）值更低。本研究还确定了热老化对所有样品相关性能的影响，结果表明，与未老化的复合材料相比，所有热老化复合材料的拉伸模量值更高，但溶胀率、拉伸强度和断裂伸长率值更低。因此，基于本研究的总体结果，可以得出结论，通过引入合适的多层结构，可以防止/减少添加BiO后常见单层NR复合材料令人担忧的机械性能下降，这不仅会拓宽潜在应用范围，还会延长复合材料的使用寿命。
