Assessment of polymer composite reinforced with nanomaterial against ionizing radiation

Introduction: Unwanted exposure of ionizing radiation may result in carcinogenesis, cell mutations, and organ failure. High-atomic number elements such as lead, tungsten, bismuth have been traditionally used for radiation protection. Theoretical and practical studies have shown that a variety of shielding materials e.g. polymer composites (PCs) can be used for attenuation of the undesired ionizing radiations. The goal of the present study is to review the efficacy of the PCs reinforced nanomaterials (NMs) for routine protection. Materials and Methods: The relevant papers were searched in PubMed, Ovid, and Scopus databases using "polymer composite", "radiation", and "protection" as keywords. Literature containing information of recent developments based on PCs reinforced nanotechnology was evaluated. The selected studies were examined using the following topics as guidelines: the PCs effectiveness on the shielding to obtain As Low as Reasonably Achievable (ALARA), focus on high energy/charge, and overall recommendation for clinical practice. Results: High atomic numbers materials such as lead is used for shielding against high- energy X and γ-rays. In addition to the fact that such substances may not be able to attenuate all photons of the incident radiation; production of secondary radiation is also probable in them. This requires additional shielding may increase the weight of the shield and its cost. The most serious problem with the routine radioprotective instruments, made from these materials, is that they are heavy and bulky. The radiation type and energy are the other important factors governing the radiation shielding design. Nowadays, novel shielding materials have been introduced in which some problems including weight, toxicity, cost- effectiveness, and durability have been improved. A variety of PCs have been investigated for radiation shielding; however, only the PCs reinforced with NMs have shown the effectiveness of radiation attenuation. This is because of the large surface-to-volume ratio and the concept of “self-healing or self-repair”. ”. In PCs shielding, regardless of the material being used, the absorption was independent of the atomic number of material and can be customized according to the specific application (radiation type). To obtain maximum protection, based ALARA, with PCs shielding, using few heavy atoms within the light matrix is necessary. Many studies have showed shielding using PCs reinforced with NMs absorb effectively fast neutrons and also can reduce the secondary gamma radiations and thermal neutrons. Conclusion: Polymers reinforced with micro- or nanoscale structures have great potential to be used as radiation shielding materials in medical uses, aerospace, and nuclear reactors.