Assessment of New Composites Containing Polyamide-6 and Lead Monoxide as Shields against Ionizing Photonic Radiation based on Computational and Experimental Methods

Assessment of New Composites Containing Polyamide-6 and Lead Monoxide as Shields against Ionizing Photonic Radiation based on Computational and Experimental Methods | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Assessment of New Composites Containing Polyamide-6 and Lead Monoxide as Shields against Ionizing Photonic Radiation based on Computational and Experimental Methods Shahryar Malekie, Hassan Shooli, Mohammad Amin Hosseini This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1176766/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract This study aimed to introduce new composites, containing polyamide-6 (PA6) and lead monoxide (PbO), to protect against ionizing photon sources used for diagnostic and therapeutic purposes. Five composites, containing various weight percentages of PbO filler (0, 5, 10, 20, and 50%), were developed in this study. Initially, the numerical attenuation value was estimated using XMuDat program by calculating the mass attenuation coefficients at different energy levels. Next, the samples were synthesized based on the melt-mixing method in a laboratory mixing extruder, and their characteristics were determined by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Finally, experimental radiation attenuation tests were carried out. Based on the SEM results, the acceptable filler weight percentage was up to 20%; however, substantial aggregates formation was observed at the highest weight percentage. The results of XRD analysis showed a higher tendency for crystallization by decreasing the amorphous area, while increasing the filler weight percentage. Moreover, the amount of mass loss was monitored at different temperatures, revealing that the filler incorporation improved the thermal durability of the samples. According to the radiation results, a good agreement was observed between the experimental and computational data, except when aggregates formation was substantial. According to the experimental data, by increasing the lead weight percentage from 0% (crude PA6) to 50%, the half-value layer decreased from 3.13 to 0.17 cm at an energy level of 59 keV and from 7.28 to 4.97 cm at an energy level of 662 keV. Considering these promising results, the applicability of PA6/PbO composites for protection against low- and medium-energy ionizing photon sources must be investigated in future studies. Polymeric composites Polyamide 6 Lead monoxide Radiation shields. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Today, the risk of intended or unintended exposure to ionizing radiation has increased in humans due to their increasing tendency to develop and use new technologies [ 1 ]. Some of the causes of exposure to ionizing radiation include cosmic rays, fuel processing, nuclear fusion processes, industrial radiation processing (especially in the food and health sectors), and long-term use of X-rays and gamma rays for diagnostic and therapeutic purposes [ 2 – 3 ]. Despite these advantages, radiation hazards and protection remain serious health concerns [ 2 , 4 ]. The use of adsorbents for the development of protectants is a well-known strategy. Lead, as an element best known for its high atomic number, shows high efficiency in absorbing radiation. Besides, due to its high abundance and cost-effectiveness, major attention has been paid to this element. For many years, lead products have been the best available option for fabricating fixed (e.g., walls and blocks) or portable (e.g., aprons, glasses, gloves) protection equipment [ 5 ]. However, the challenges and problems of using lead products have become more prominent over time. Today, the disadvantages of using bulk lead in the construction of shields have been addressed, such as the high weight of lead products, health and environmental challenges due to high lead toxicity, and high fragility of these products [ 6 – 7 ]. In recent years, different approaches have been employed to obviate the mentioned challenges. The use of materials, such as bismuth, tungsten, and tin as alternatives to lead, is one of these well-known approaches [ 6 – 10 ]. It seems that application of a novel method involving the use of nanocomposites can resolve many of these challenges. In this method, a combination of polymers (matrix) and nanoscale heavy metals (fillers) is often used. It is assumed that with a suitable distribution of particles in the matrix, the surface -to-volume ratio increases, leading to a higher radiation absorption efficiency and an optimal reduction in the product size [ 7 , 11 ]. Therefore, in this method, the radiation protection products are expected to have higher efficiency, flexibility, chemical and thermal stability, and biocompatibility [ 5 – 7 ]. Despite the mentioned disadvantages for lead, previous studies have reported promising results by using nanosize or microscale lead (rather than bulk use) with various chemical structures (e.g., PbO, PbO2, Pb3O4, or chloride forms). Overall, these approaches provide an opportunity to optimize the use of lead in new forms [ 5 ]. So far, numerous experimental studies have been conducted on the applicability of lead polymers for radiation protection. Different concentrations of lead monoxide (PbO) have been assessed in unsaturated polyesters with a ‍cesium-137 source [ 12 ] by adding modified nanoclay [ 13 ]. Satisfactory radiation protection efficiency and structural properties have been reported, based on the comparison of bulk and nanoscale PbO features in heavy polyethylene [ 14 ] or a linear low density polyethylene in exposure to mid- and high-energy gamma radiation [ 15 ], besides other compounds, such as nano-PbO reinforced into epoxy resins [ 16 ], polyvinyl alcohol [ 17 ], and polyesters [ 18 ]. In line with experimental studies, several other studies using computational methods have confirmed the efficiency of lead-based composites [ 19 – 20 ]. Moreover, polymer-based composites and nanostructures have shown unique features in other radiation fields, including the basic design and development of ionizing radiation dosimeters [ 21 – 27 ]. Despite the reported benefits of polymeric composites in ionizing radiation and the possibility of reusing optimized lead composites as radioprotective materials, there is a need for further scientific research on these composites. Therefore, in the present study, new composites, consisting of PbO and polyamide-6 (PA6), were fabricated, and protection against X-rays and gamma rays was investigated in a broad energy range, using computational and experimental methods. To the best of our knowledge, this is one of the first reports on composites containing lead fillers in a polymeric PA6 matrix. 2. Materials And Methods 2.1. Theoretical section: Estimation of radiation attenuation properties of the compounds This study primarily aimed to assess the protective effects of novel PA6/PbO composites against X-ray and gamma radiation, using computational approximation and experimental methods. The studied composites contained PbO (ρ = 9.53 g/cm 3 ) as the filler and PA6 ([C 12 H 22 N 2 O 2 ] n , ρ = 1.13 g/cm 3 ) as the polymeric matrix [ 28 ]. In this study, five composites containing different weight percentages of PbO (0, 5, 10, 20, and 50%) were fabricated. Table 1 shows the distribution of elements in each compound. The nominal density of each compound was calculated, based on the American Society for Testing and Materials (ASTM) D792-91 standard (1991) (the last column of Table 1 ), using the following formula [ 29 ]: $$\rho =\frac{1}{\frac{{w}_{1}}{{\rho }_{1}}+\frac{{w}_{2}}{{\rho }_{2}}} \left(1\right)$$ where w 1 and ρ 1 denote the weight percentage and density of the fillers (i.e., PbO), respectively, and w 2 and ρ 2 represent the corresponding parameters for the matrix (i.e., PA6), respectively. Table 1 Characteristics of the studied composites consisting of five different combinations of PA6 and PbO. Sample wt% (PbO) H C O N Pb ρtotal (g/cm 3 ) PA6 (crude) 0 0.098 0.637 0.124 0.141 0.000 1.130 PA6/PbO-5% 5 0.093 0.605 0.118 0.138 0.046 1.182 PA6/PbO-10% 10 0.088 0.573 0.111 0.134 0.093 1.239 PA6/PbO-20% 20 0.078 0.509 0.099 0.127 0.186 1.372 PA6/PbO-50% 50 0.064 0.417 0.081 0.117 0.320 2.020 Moreover, it is possible to approximate the radiation absorption and attenuation properties of materials and compounds both before and after synthesis, based on calculations using the dedicated codes and programs. Besides, experimental analysis of attenuation and absorption properties in a wide range of beam energies, which is by itself an interesting research topic, has limitations in practice. Therefore, use of dedicated software programs, followed by validation of the results using experimental tests in exposure to several radioactive sources (i.e., comparison of the results of experimental and computational methods), has always been interesting to researchers [ 30 – 33 ]. Some important parameters for estimating the behavior of materials in exposure to X-rays and gamma rays include the linear attenuation coefficient (µL), total mass attenuation coefficient (µ/ρ), and half-value layer (HVL), which are measured with dedicated Monte Carlo codes and software programs. One of the well-known dedicated programs is XMuDat [ 34 ], which can measure parameters, such as the mass attenuation coefficient, for six different compounds simultaneously in a broad photon energy range (0.001-50 MeV). In this program, it is essential to include the content of each compound (e.g., type of elements and weight percentages). Calculations are performed according to the algorithms in the program and the data of a reference library. It is possible to use one of the two references by Hubbell et al. [ 35 ] or Boone et al. [ 36 ] as default calculations, where the mass attenuation coefficients of different elements (Z=1-92) at different energy levels are described. The total mass attenuation coefficient (µ/ρ total ) of every compound at any given energy level was calculated using the following formula: $$({\frac{\mu }{\rho })}_{total}=\sum {w}_{i}\times ({\frac{\mu }{\rho })}_{i} (2)$$ where w i is the weight fraction of each element in the compound, and \(({\frac{\mu }{\rho })}_{i}\) represents the total mass attenuation coefficient (measured by dividing the linear attenuation coefficient [µL] by the element density [ρ] at the designated energy level) [ 37 ]. It is possible to obtain these numerical values and standard graphs in the software for a maximum of six compounds. By determining the final \(({\frac{\mu }{\rho })}_{total}\) value at the specified energy level and considering the density of the composite, the HVL value was determined as follows [ 6 ]: $$HVL=\frac{ln2}{{\mu }_{L}} \left(3\right)$$ In the present study, the numerical values for the total mass attenuation of the five samples, listed in Table 1 , were calculated in XMuDat. The input information for the program included data, such as the type and weight fraction of the elements (Table 1 ). Calculations were performed based on the data library reported by Boone et al. for photon emissions in an energy range of 0.001-10 MeV. 2.2. Experimental Section 2.2.1. Materials and equipment for characterization of the samples Polyamide 6 (PA6)-Akulon® F223-D (DSM products) was purchased from the market. Nanoscale PbO powder (in form of a 25-g stock solution) was purchased from Aria Chemical Co. (Tehran, Iran) and used in experiments after its qualification was verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM) examinations. The following characterization tests were carried out on the PA6/PbO composites: SEM (TESCAN MIRA3, Czech Republic); thermogravimetric analysis (TGA) over a temperature range of 20-600°C at a rate of 10°C/min in air using a TGA analyzer (Netzsch TG 209F3 Tarsus, Frankfurt, Germany); and XRD analysis for phase detection (X'Pert PRO MPD, PANalytical, Almelo, Netherlands). All analyses were performed at room temperature. The X-ray radiation parameters were set at 40 kV and 30 mA (target=Cu Kα, λ = 1.54 Å). It should be noted that in this system, the scans were acquired over a 2θ angle range of 1° to 100° (with 0.026° intervals) in a counting time of 0.5 sec. All of the three mentioned examinations were performed at Razi Metallurgical Research Center (Alborz, Iran) as a service provider. 2.2.2. Fabrication of PA6/PbO composites The fabrication of five PA6/PbO composites, including different weight percentages of PbO filler (0, 5, 10, 20, and 50%), was initiated by the melt-mixing method. The final fabrication and preparation phases were conducted, using hot and cold pressing processes. During the synthesis process, PA6 and PbO powders were initially weighed, based on the predetermined mass ratios on a four-point digital scale (CAS model) and then placed in an oven at 90°C for several hours to ensure dehumidification. Before synthesis, granulated PA6 particles were exposed to liquid nitrogen for ten minutes to reaffirm their dryness and fragility. Next, an ultra-centrifugal mill (ZM 200, Retsch, Germany) was used at 14,000 rpm to reduce the particle size to 50 µm. Considering the melting point of polyamide, the samples were synthesized in a laboratory mixing extruder (Dynisco, USA) over a temperature range of 220-245°C at 50 rpm. The synthesis conditions were set based on the operator’s experience and a previous study [ 14 ]. Finally, the materials were formed into galvanized sheet molds with dimensions of 8×8×0.1 cm 3 . For molding, the synthesized materials were initially poured into molds and then formed by hot and cold pressing machines (Toyo Seiki Co., Japan). For this purpose, first, hot pressing was performed for each sample at an approximate temperature of 240°C, considering the melting point of polyamide, less than 25 kg/cm 2 pressure for five minutes. Next, a cold pressing machine, the plates of which were being cooled by water spray, was applied immediately at a similar pressure for three minutes. 2.2.3. Experimental analysis of radiation attenuation The linear attenuation coefficients (µL) of the samples were measured, using an experimental method according to a previous report [ 9 ] over a descending photon energy range with a narrow-parallel beam geometry. After the synthesis and molding of the fabricated samples, they were subjected to experimental radiation tests. First, the sheet composites, with dimensions of 8×8×0.1 cm 3 , were cut into four sections. To determine the experimental linear attenuation coefficients and HVL values of the composites, a narrow-parallel geometry was considered (Figure 1 ) in the presence of two standard low-energy ( 241 Am, Eγ = 0.059 MeV) and medium-energy ( 137 Cs, Eγ = 0.662 MeV) gamma-ray sources. The experiments were performed in a specialized laboratory for Secondary Standard Dosimetry Laboratory (SSDL) in Karaj, Iran. For the experimental radiation tests (Figure 1 ), a calibrated detector, equipped with a CsI(Tl) cylindrical probe (NT-812), was used. The instrument was connected to a power supply and an amplifier (Novin-Teyf, Iran), as shown in Figure 1 . For the initial narrowing of beams, a hole was created in parallel with the probe axis on the lid of the cylindrical chamber, where the standard radiation source was placed (Figure 1 ). To measure the radiation intensity at the desired energy level, the output spectrum of the detector was initially measured in the presence of the test material with different thicknesses (t=1-4 mm) or in its absence (t=0). Next, the areas under the curve at the specified peaks (Figure 2 ), corresponding to the measured energy intensities (I 0 , I 1 , I 2 , I 3 , and I 4 ) in different layers, were used to determine the linear attenuation coefficients, based on the Beer-Lambert formula [ 9 ]: $${\mu }_{L}=\frac{\text{ln}\left(\frac{{I}_{0}}{I}\right)}{t} \left(4\right)$$ The net value of the linear attenuation coefficient for each sample at a specific energy level was determined by analyzing the linear regression, as shown in Figure 2 ; the curve slope corresponds to the linear attenuation coefficient. After determining the experimental value of the linear attenuation coefficient, the HVL value can be calculated at each energy level using Equation 3 . 4. Results & Discussion 4.1. Morphological analysis of the samples by SEM The pre-synthesis SEM micrographs of PbO powder, samples containing 5, 10, 20 and 50 wt% of PbO, and lead-free sample (crude PA6) are shown in Figure 3 . To better understand the distribution of particles, images were acquired at two different magnifications. Figure 3 A ( A1, A2 ) shows PbO powder before synthesis, with different particle sizes (reaching even <100 nm). Figure 3 B (B1, B2 ) presents the crude PA6 (filler matrix), allowing for a better assessment of the filler distribution; it seems that the polyamide matrices are arranged as sheets next to each other, similar to microfibers. Moreover, the filler distribution at weight percentages of 5% and 10% in PA6 after hot and cold pressing processes is presented in Figure 3 C (C1, C2) , Figure 3 D (D1, D2) respectively. The nano-PbO particles showed a relatively consistent distribution on the polymer surface. However, a slight increase was observed in the filler size, using 10 wt% filler due to the accumulation of particles. Likewise, by increasing the filler weight percentage to 20% and 50%, the asymmetrical increase in the filler size became more noticeable on the surface ( E1, E2 & F1, F2 ); this increase was even more noticeable than that observed in fillers with lower weight percentages. Despite the accumulation of filler particles in both 20% and 50% PbO composites, 20% PbO seemed to have a more symmetrical distribution on the polymer surface. However, in the 50% PbO sample, an increase in the filler percentage and high adhesion between the filler particles resulted in the accumulation of particles with asymmetrical sizes. In other words, as shown in Figure 3 F (F1, F2) , the agglomerations of the fillers were more significant at this concentration, reflecting the formation of stronger van der Waals forces among filler particles, with an increase in the weight percentage of heavy metal fillers (e.g., lead and bismuth) dominating the filler-polymer bonds [ 9 , 14 , 38 ]. This finding is consistent with the previous studies in composites, containing lead at a weight percentage of 20% or higher [ 14 , 15 ]. To assess the quality of elements on the surface of the composites, an energy-dispersive X-ray (EDX) analysis was performed on the sample containing 10% lead (Figure 4 ). As can be seen, the absorption edges of lead (Mα and Mβ) and other elements, such as carbon and oxygen (Kα), emerged as fingerprints within the selected energy range, confirming the presence of lead (as filler) in the synthesized samples. It should be noted that the absence of hydrogen, as a light element, is related to the inherent limitations of this analytical test [ 39 ]. 4.2. Results of XRD analysis of PbO-containing composites Figure 5 presents the results of XRD analysis of the studied composites containing different filler weight percentages (5, 10, 20, 30, and 50 wt%) in the PA matrix at different intensities over different 2𝜃 angles. The observed XRD pattern indicated the following results: 1) The peaks observed in the first region, especially at 20.26° and 23.5° angles, were detected in all samples; according to previous studies, these peaks belonged to PA6 [ 40 , 41 ]. Gupta et al., besides mentioning the possible formation of two alpha and gamma crystalline phases in PA6, conducted phase detection by XRD analysis at different temperatures and observed similar peaks at 240°C (similar to our results), which were attributed to the dominance of the alpha phase over the gamma phase in PA6. They also observed the superiority of the alpha phase over the gamma phase in terms of thermodynamic stability [ 40 ], which is a favorable feature of the composites investigated in the present study. On the other hand, following phase extraction, the samples showed a red color in the graphs. After analysis and matching with the Joint Committee on Powder Diffraction Standards (JCPDS) cards, the Massicot cards (card No. 4747-338 and 05-0570) were also identified. According to previous studies, PbO is present in two crystalline phases of α-PbO and β-PbO [ 42 ]. While the alpha phase is tetragonal, the beta phase (i.e., Massicot) has an Orthorhombic shape with unequal sides. Also, in the graphs, the geometric dimensions of each sample are well characterized (a=5.4, b=4.7, c=5.8 & α = β = γ = 90°). 2) In addition to the abovementioned peaks, flattening of the primary regions (2𝜃 angle<10°) was also noticeable in the XRD graphs; this region is clearly visible in Figure 3 A (crude PA6 sample). With an increase in the filler weight percentage, this area became smaller, and it was hardly visible at the highest filler weight percentage (Figure 3 D). Meanwhile, enhanced peak intensities at other angles (2𝜃 angle≈20.26°, 23.5°, and 29.1°) could indicate more crystallization of the composites by increasing the weight percentage of lead (in exchange for a decrease in the amorphous region). Nevertheless, increasing the filler weight percentage did not introduce tangible changes in the dominant shape or other parameters of the lattice. 4.3. Thermal analysis of composites The thermal stability analysis of the three selected compounds, including crude PA6 and composites containing 10 and 20 wt.% PbO, was conducted, using a thermogravimetric analysis (TGA) and a differential thermal analysis (DTA); the results are presented in Figure 6 . The analyses were performed under N 2 atmosphere in a temperature range of 20-600°C (at a heating rate of 10°C/min), according to the ASTM E1131-08 standard (2014). The TGA curves revealed multi-phase trends in the mass changes of all composites, but at different intensities. For example, in the crude PA6 sample, the mass reduction was less than 10% before reaching a temperature of 400°C, corresponding to a continuous glass transition in the DTA diagram; this trend is completely compatible with previous reports [ 43 ]. It should be noted that the mass change in this region was attributed to a reduction in moisture and dehumidification of the sample [ 44 ]. On the other hand, the mass change trends of samples containing 10 and 20 wt% lead were observed in the same area at a lower temperature, indicating a shift toward a lower glass transition temperature by increasing the filler weight percentage. The rates of mass reduction by increasing the lead concentration were 15.5% and 22.7%, respectively. In line with our observations, another study attributed this trend to the increased aggregate formation by the filler in the composite [ 9 ]. Considering the trend of changes in the curves by increasing the temperature, the next round of decomposition occurred over a temperature range of 440-442°C, where a sharp weight loss was clearly observed in all DTA graphs. The weight loss percentages compared to the initial peak were 90.5%, 66%, and 54% for the crude PA6, 10% lead-containing composite, and 20% lead-containing composite, respectively. Sharp changes in this area (known as the melting zone) can be attributed to chemical decomposition due to the loss of CO 2 by the samples in this thermal range [ 44 ]. As can be seen in all three graphs, at the final temperature point (600°C), the residual masses were 1%, 8%, and 13.5% for the crude PA6, 10% lead-containing composite, and 20% lead-containing composite, respectively. Based on these observations, increasing the percentage of lead filler led to a reduction in weight loss and a boost in the thermal stability of the studied PA6/PbO composites. 4.4. Results of gamma-rays attenuation on the samples The mass attenuation coefficients (µ/ρ) of the five studied composites were calculated in XMuDat. For a better understanding of this phenomenon, the trends were assessed in a photon energy range of 1-10,000 keV, as shown in Figure 7 . As shown in Figure 7 , by increasing the energy level, the crude PA6 showed a slight gradual reduction in the attenuation coefficient. However, the stepwise addition of PbO up to 50% of the composite weight resulted in an increase in the attenuation coefficient, which is especially evident in the low- and medium-energy ranges (1-500 keV). Besides, the curve analysis of lead-containing composites showed a sudden noticeable drop in the mass attenuation coefficient in low-energy regions (<100 keV) compared to higher-energy zones. The sharp peaks observed in this area might indicate the dominance of photoelectric effects at some energy levels (e.g., 88 keV and 15 keV for K- and L-absorption edges of lead, respectively) [ 5 ]. Based on these results, an increase in the weight percentage of lead offers a more optimal attenuation in the mentioned energy range. Table 2 presents the linear attenuation coefficients calculated by XMuDat program and the experimental method at two energy levels of 59 and 662 keV. By increasing the lead oxide filler weight percentage, the attenuation trend improved, as evidenced by an increase in the mass attenuation coefficients. Despite differences in the values obtained by these two approaches, an acceptable agreement was observed between the experimental and computational data; also, these differences depended on the concentration of lead. The difference observed between the computational and experimental data may be partly explained by differences in the distribution of elements in the samples. In other words, in computational programs, such as XMuDat, elements are considered to be uniformly distributed in the samples (i.e., a uniform filler distribution in the matrix). However, in reality, as shown in SEM images (Figure 3 ), this distribution is not necessarily uniform and may be accompanied by the formation of agglomerations, which is more evident at a weight percentage of 50%. The importance of this factor in the agreement of computational and experimental data has been highlighted in a similar study [ 45 ]. Moreover, to better understand the experimental results, a comparison with the findings of three experimental studies on similar PbO concentrations is presented in Table 2 (columns 4 to 6). As can be seen, the experimental data of the present and previous studies were consistent for PbO weight percentages up to 20%; however, differences were still evident at the highest weight concentration (50%), associated with numerous aggregates. Despite the abovementioned findings, some errors in the experimental method cannot be overlooked, such as errors in the geometrical arrangements, causing scattered beams to reach the detector, besides deviation from an ideal geometry. This issue is particularly important at lower energies (i.e., 59 keV in the present study). Besides, other errors are possible, such as detector errors (e.g., dead time). Despite similar filler concentrations in the studies described in Table 2 , different polymeric matrices were used in these studies. Harish et al. [ 12 ] used unsaturated polyester (1.2 g/cm 3 ); Bagheri et al. [ 13 ] used unsaturated polyester plus 5% nanoclay filler; and Mahmoud et al. [ 14 ] used a high-density polyethylene (0.953 g/cm 3 ). These differences caused slight variations in the amount and type of elements in the products and consequently led to variable degrees of attenuation. As the final density of the product seems to affect the radiation attenuation [ 13 ], accurate measurement of the final density of materials can somehow explain the observed differences. Table 2 The linear attenuation coefficients measured in the present study using the computational and experimental methods compared to the results of similar previous studies PbO wt% Calculated by XMuDat (this study) Experiments (this study) Harish et al. 2008 [ 12 ] Bagheri et al. 2018 [ 13 ] Mahmoud et al. 2018 [ 14 ] E=662 (keV) 5 0.102 0.101 0.0997 0.089 - 10 0.109 0.091 0.114 0.102 0.105 20 0.123 0.130 0.1264 0.119 - 50 0.196 0.140 0.206 - 0.189 E=59 (keV) 5 0.496 0.400 - - - 10 0.800 0.605 - - 0.599 20 1.555 1.050 - - - 50 5.130 4.050 - - 4.488 Finally, the gamma radiation attenuation improved by increasing the weight percentage of the lead oxide, as evidenced by the measured HVL values (Figure 8 ). By increasing the weight percentage of the lead oxide from 0% (crude polyamide) to 50%, the HVL value decreased from 3.13 to 0.17 cm at energy intensity of 59 keV and from 7.28 to 4.97 cm at an energy intensity of 662 keV. In other words, by increasing the energy and penetrating depth of gamma rays, the thickness required to block half of irradiated gamma rays also increased. 5. Discussion In recent years, due to the increasing demand of ionizing radiation in various industries and medicine, the importance of protection against radiation has increased. In this regard, polymeric composites, as novel alternatives to traditional materials, have been proposed for designing protective shields and addressing the challenges of conventional methods [ 5 , 7 , 11 ]. Previously, polymeric composites offered satisfactory results for the fabrication and design of radiation dosimeters [ 21 – 27 ]. The disadvantages of using bulk amounts of lead for constructing radiation protectants include high toxicity, environmental pollution, undesirable mechanical stability, and high weight of lead products (due to high lead density). However, due to its high atomic number, wide availability, and most importantly, its capacity to transform into micro- and nano-dimensions (in various chemical forms) promise the optimized reuse of lead, which has shown satisfactory results in the previous studies [ 5 – 7 ]. In the present study, new PbO/PA6-based composites, consisting of different weight percentages of PbO (0, 5, 10, 20, and 50%), were fabricated and then characterized using both computational (XMuDat program) and experimental (characterization and experimental tests) methods. According to the computational analyses (Figure 1 ), before the synthesis of composites, lead-containing samples were predicted to show better attenuation compared to lead-free samples (crude PA6). By increasing the weight percentage of PbO, the attenuation trend improved, as evidenced by an elevation in the mass attenuation coefficients. This finding was more evident (as peaks) at energy intensities of 15 and 88 KeV, which represent the K- and L-absorption edges of lead and indicate the predominance of the photoelectric effect in these composites [ 5 ]. It seems that in diagnostic procedures, such as radiology and nuclear medicine, these composites can be effective in protection against radiation. In the experimental section of this study, the composites were initially fabricated and then characterized. For this purpose, the melt-mixing method, which is a cost-effective and relatively convenient method, was used to synthesize the samples in an extruder. The required adjustments in the device, such as temperature (based on the melting point of PA6), rotation speed and duration, were set based on the operator’s experience and the results reported in a study by Mahmoud and colleagues [ 14 ]. The experiments were conducted in a specialized laboratory for fabricating plastics and polymers. The characterization of the samples based on SEM showed that up to a filler weight percentage of 20 wt%, there was a relatively symmetrical distribution of PbO particles in the polyamide; however, by increasing the weight percentage, the filler started to form aggregations that were seen as large lumps at the highest weight percentage (50%). In the EDX analysis of a selected sample, the fingerprints of lead and a number of other elements in the composites were observed (Figure 4 ). To explain the increasing accumulation of filler particles, Mehrara et al. referred to the formation of strong van der Waals forces among filler particles, dominating the filler-polymer bonds [ 9 ]. This observation is consistent with previous reports on other lead-containing composites with similar weight percentages [ 14 ]. It should be noted that in this study, for the first time, a SEM image of a sample containing 50% lead oxide was acquired. The phase detection and evaluation of the crystal network of the composites via XRD showed that PA6 was in the form of alpha crystals in the samples. Previous studies have reported that this type of polyamide is sensitive to temperature and may form different phases upon thermal changes [ 40 , 43 ]. In this study, the emergence of peaks at 20.26° and 23.5° angles indicated the predominance of the alpha phase, which might be attributed to the sample synthesis and pressing processes at temperatures approximating 240°C. Besides, by increasing the filler weight percentage, the flattening of initial zones (2𝜃 angle<10°; amorphous zone) started to decrease, whereas greater sharpness and more crystallization were observed at angles corresponding to PbO. This finding was also confirmed after matching with the JCPDS standard cards and detection of the Massicot phase (lead mineral form) (codes 4747-1387 and 05-0570, respectively) (Figure 5 ). These observations are in agreement with previous studies [ 14 ]. In the current study, thermal stability was assessed using the TGA and DTGA analyses in three samples (crude PA6 and composites containing 10% and 20% lead oxide, respectively). In the crude PA6 sample (Figure 6 A), before reaching a temperature of 400°C, there was a relatively smooth and continuous glass transition, which could be attributed to the dehumidification of the sample [ 44 ]; it should be noted that for samples containing a lead oxide filler (Figure 6 B & 6 C), the glass transition temperatures were lower (359°C and 347°C for 10% and 20% filler weight percentages, respectively). A similar trend was also observed in a previous study [ 9 ], which could be attributed to the presence of lumps and deformation in the mentioned temperature range. By increasing the temperature and reaching the melting zone, the superiority of lead-containing samples was supported by their less significant weight loss. This superiority remained noticeable until the end-point temperature (600°C) and was verified by the quantitative assessment of the residual mass. Therefore, it can be concluded that increasing the lead filler ratio in the composites caused them to lose less weight and acquire higher thermal stability. In the second section of the experimental analyses, the radiation attenuation trends for photon sources were assessed at 59 keV (low energy) and 660 keV (medium energy) in the lead-containing samples in a specialized laboratory. Notably, the results of this section were consistent with the theoretical results for lower filler weight percentages. To explain this finding, it should be noted that in the computational method, it is assumed that the samples have a homogeneous distribution of elements; therefore, in practice, samples with less formation of lumps showed a better agreement with the computational data. On the other hand, significant differences were observed in samples with a higher filler percentage (e.g., 50%) due to the formation of numerous lumps. A comparison between our experimental results and those of previous studies (Table 2 ), indicating a slight difference in the reported experimental data, can also confirm this finding. In this regard, Mahmoud et al. (2020), by examining lead filler weight percentages up to 10%, reported a good agreement between the experimental and computational data due to the uniform distribution of the filler [ 45 ]. According to our experimental results, by increasing the weight percentage of lead from 0% (crude PA6) to 50%, the HVL values decreased from 2.13 to 0.17 cm at an energy level of 59 kV and from 7.21 to 4.97 cm at an energy level of 662 keV. This study had some limitations, based on which we have made some suggestions for future studies. Considering the acceptable efficiency of the composites containing lead up to a weight percentage of 20%, composites with other lead weight percentages (20–50%) can be assessed in future experiments. In this study, thermal stability was investigated in only three samples; it is advisable to extend this analysis to other samples, as well. Finally, further experimental analysis of the radiation attenuation and absorption capacity of PbO/PA6 composites can be performed at other energy levels to verify the protective efficiency of these composites. To the best of our knowledge, this study on PA6/PbO composites is among the first reports on these novel radioprotectants; therefore, further investigation is strongly recommended. 6. Conclusion We studied the applicability of novel PA6/PbO-based composites, containing different weight percentages of PbO (0, 5, 10, 20, and 50%) as protectants against X-ray and gamma rays, using both computational and experimental methods. The composites were synthesized in a laboratory mixing extruder and characterized by various tests, including SEM, XRD, TGA, and experimental radiation tests. The SEM images showed the acceptable symmetrical distribution of PbO particles (weight percentages up to 20%) in PA6. Moreover, an increase in the formation of crystalline networks, along with decreased amorphous zones in the composites, was observed by increasing the filler weight percentage, as evidenced by the XRD analysis. Besides, a thermal analysis was conducted for the selected samples, containing 0%, 10%, and 20% PbO from room temperature up to 600°C. As shown in the TGA and DTGA analyses, the total weight loss reduced, and thermal stability improved in the lead-containing composites. However, a descending trend in the glass transition temperature was seen in the samples containing fillers, which was probably related to aggregates deformation. Overall, the studied composites showed an acceptable radioprotective efficiency against low- and medium-energy radiations, and a good agreement was observed between the experimental and computational data for lead-containing composites up to weight percentages of 20%. However, the formation of lumps and heterogeneity in the filler distribution of the composite could markedly affect the radiation protection efficiency. It was found that a higher heterogeneity would result in the greater deviation of the measured attenuation coefficient from the calculated value. Here, at the highest filler weight percentage (50%), this heterogeneity reduced the consistency between the experimental and computational data and reduced the radiation attenuation efficiency. Since PA6/PbO-based radioprotectant composites are novel materials, it is strongly recommended to further investigate their characteristics in future experiments while considering the limitations of this study. Declarations Conflict of Interest The authors declare no conflict of interest. Acknowledgements This study was extracted as part of a Master's thesis by Mr. H. Shooli, MSc student at Islamic Azad university of Arsanjan. We appreciate those who supported us in conducting this study, especially the personnel and management support and cooperation of the staff at the Nuclear Science and Technology Research Institute of Iran which resulted in the success of this research project. Furthermore, we would like to offer special thanks for the sincere spiritual support and encouragement provided by the Vice-Chancellor of Research at the Shiraz University of Medical Sciences (SUMS). References [1] Classic K, Le-Guen B, Kase K , Vetter R. Safety and radiation protection culture. In Radiological Safety and Quality. 2014; pp. 263-277. Springer, Dordrecht. [2] Holmberg O, Czarwinski R, Mettler F. The importance and unique aspects of radiation protection in medicine. European journal of radiology. 2010; 76(1): 6-10. [3] Zakariya N, Kahn, MTE. Benefits and biological effects of ionizing radiation. Sch. Acad. J. Biosci. 2014; 2(9): 583-591. [4] Ryan JL. Ionizing radiation: the good, the bad, and the ugly. Journal of Investigative Dermatology. 2012; 132(3):985-993. [5] Low IM, Azman NZN. Polymer Composites and Nanocomposites for X-Rays Shielding. Springer. 2020 DOI: 10.1007/978-981-13-9810-0. [6] Kazemi F, Malekie S, Hosseini MA. A Monte Carlo study on the shielding properties of a novel polyvinyl alcohol (PVA)/WO3 composite, against gamma rays, using the MCNPX code. Journal of Biomedical Physics & Engineering . 2019; 9 (4):465. [7] Nambiar S, Yeow JT. Polymer-composite materials for radiation protection. ACS applied materials & interfaces. 2012; 4(11):5717-5726. [8] Malekie S. Hajiloo N. Comparative study of micro and nano size WO3/E44 epoxy composite as gamma radiation shielding using MCNP and experiment. Chinese Physics Letters. 2017; 34(10): p.108102. [9] Mehrara R, Malekie S, Kotahi SMS, Kashian S. Introducing a novel low energy gamma ray shield utilizing Polycarbonate Bismuth Oxide composite. Scientific Reports. 2021; 11(1): 1-13. [10] Zarei M, Sina S, Hashemi SA. Superior X-ray Radiation Shielding of Biocompatible Platform Based on Reinforced Polyaniline by Decorated Graphene Oxide with Interconnected Tungsten-Bismuth-Tin complex. Radiation Physics and Chemistry.2021:p.109588. DOI: 10.1016/j.radphyschem.2021.109588. [11] Mansouri E, Mesbahi A, Malekzadeh R, Mansouri A. Shielding characteristics of nanocomposites for protection against X-and gamma rays in medical applications: effect of particle size, photon energy and nano-particle concentration. Radiation and Environmental Biophysics. 2020;59: 583–600. [12] Harish V, Nagaiah N, Prabhu TN, Varughese K. 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Journal of Radioanalytical and Nuclear Chemistry. 2015;306(1):107-17. [16] Azman NZ, Siddiqui SA, Hart R, Low IM. Microstructural design of lead oxide–epoxy composites for radiation shielding purposes. Journal of applied polymer science. 2013;128(5):3213-9. [17] Shafka ZM, Hannora AE, Sherif MM. Preparation of lead-polymer nano composite for nuclear shielding applications. Int. J. Research Appl. Sci. & Engin. Technol. 2015;3. [18] Yulianti I, Susanti T, Setiawan R. Lead-polyester resin composite as an alternative material for radiation protection in radiography. InJournal of Physics: Conference Series. 2020; 1567(3): p. 032069). IOP Publishing. DOI:10.1088/1742-6596/1567/3/032069. [19] Sayyed MI, Akman F, Kaçal MR, Kumar A. Radiation protective qualities of some selected lead and bismuth salts in the wide gamma energy region. Nuclear Engineering and Technology. 2019;51(3):860-6. [20] Özkalaycı F, Kaçal MR, Agar O, Polat H, Sharma A, Akman F. Lead (II) chloride effects on nuclear shielding capabilities of polymer composites. Journal of Physics and Chemistry of Solids. 2020 Oct 1;145:109543. [21] Feizi S, Mehdizadeh A, Hosseini MA, Jafari SA, Ashtari P. Reduced graphene oxide/polymethyl methacrylate (rGO/PMMA) nanocomposite for real time gamma radiation detection. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2019;940:72-7. [22] Hosseini MA, Feizi S, Mehdizadeh A, Ashtari P, Mojtahedzadeh M, Mosleh-Shirazi MA, Alipour A. Dosimetric investigation of a new quantum dots/nanocomposite (CdTe QDs/PVK) sensor for real-time gamma radiation detection. Applied Physics A. 2019;125(12):1-8. [23] Rahimi A, Ziaie F, Sheikh N, Malekie S. Calorimetry System Based on Polystyrene/MWCNT Nanocomposite for Electron Beam Dosimetry: A New Approach. Nanotechnologies in Russia. 2020;15(2):175-81. [24] Mosayebi A, Malekie S, Rahimi A, Ziaie F. Experimental study on polystyrene-MWCNT nanocomposite as a radiation dosimeter. Radiation Physics and Chemistry. 2019; 164:108362. [25] Mosayebi A, Malekie S, Ziaie F. A feasibility study of polystyrene/CNT nano-composite as a dosimeter for diagnostic and therapeutic purposes. Journal of Instrumentation. 2017;12(05):P05012. [26] Hosseini MA, Malekie S, Ebrahimi N. The analysis of linear dose-responses in gamma-irradiated graphene oxide: Can FTIR analysis be considered a novel approach to examining the linear dose-responses in carbon nanostructures?. Radiation Physics and Chemistry. 2020;1 76:109067. [27] Ebrahimi N, Hosseini MA, Malekie S. Preliminary study of linearity response of γ-irradiated graphene oxide as a novel dosimeter using the Raman spectroscopy. Bulletin of Materials Science. 2020;43(1):1-5. [28] Jaiganesh V, Manivannan S, Manivannan S. Optimization of process parameters on friction stir welding of Nylon 6 polymer plate. InInternational Conference on Advances in Design and Manufacturing 2014. [29] ASTM Committee D-20 on Plastics. Section D20. 70.01. Standard test methods for density and specific gravity (relative density) of plastics by displacement. American Society for Testing and Materials. [30] Pavlenko VI, Cherkashina NI, Yastrebinsky RN. Synthesis and radiation shielding properties of polyimide/Bi2O3 composites. Heliyon. 2019; 5(5):e01703 [31] Saudi HA, Issa SA, Elazaka AI, Zakaly HM, Kilic G, Tekin HO. Exploration of material characteristics of tantalum borosilicate glasses by experimental, simulation, and theoretical methods. Journal of Physics and Chemistry of Solids. 2021; 159:110282. [32] Suwanmaneechot P, Bongkarn T, Joyklad P, Julphunthong P. Experimental and numerical evaluation of gamma-ray attenuation characteristics of concrete containing high-density materials. Construction and Building Materials. 2021; 294:123614. [33] Alzahrani JS, Kavas T, Kurtulus R, Olarinoye IO, Al-Buriahi MS. Physical, structural, mechanical, and radiation shielding properties of the PbO–B2O3–Bi2O3–ZnO glass system. Journal of Materials Science: Materials in Electronics. 2021;32(14):18994-9009. [34] Nowotny R. XMuDat: photon attenuation data on PC. IAEA Report IAEA-NDS 195. [35] Hubbell JH, Seltzer SM. Tables of X-ray mass attenuation coefficients and mass energy-absorption coefficients 1 keV to 20 MeV for elements Z= 1 to 92 and 48 additional substances of dosimetric interest. National Inst. of Standards and Technology-PL, Gaithersburg, MD (United States). Ionizing Radiation Div.; 1995. [36] Boone JM, Chavez AE. Comparison of x‐ray cross sections for diagnostic and therapeutic medical physics. Medical Physics. 1996;23(12):1997-2005. [37] Bagheri R, Adeli R. Gamma-ray shielding properties of phosphate glasses containing Bi2O3, PbO, and BaO in different rates. Radiation Physics and Chemistry. 2020; 174:108918.. [38] Ang HY, Toong D, Chow WS, Seisilya W, Wu W, Wong P, Venkatraman SS, Foin N, Huang Y. Radiopaque fully degradable nanocomposites for coronary stents. Scientific reports. 2018 Nov 27;8(1):1-4. [39] Scimeca M, Bischetti S, Lamsira HK, Bonfiglio R, Bonanno E. Energy Dispersive X-ray (EDX) microanalysis: A powerful tool in biomedical research and diagnosis. European journal of histochemistry: EJH. 2018;62(1). [40] Gupta B, Lacrampe MF, Krawczak P. Polyamide-6/clay nanocomposites: a critical review. Polymers and Polymer Composites. 2006 Jan;14(1):13-38. [41] Li X, Han P, Song G, Peng Z, Yu Y, Feng S, Zhou C, Li M. Assembly of polyamide 6 nanotube arrays with ordered patterns and the crystallization behavior. Materials Letters. 2015; 141:157-60. [42] Qamar A, LeBlanc K, Semeniuk O, Reznik A, Lin J, Pan Y, Moewes A. X-ray spectroscopic study of amorphous and polycrystalline PbO films, α-PbO, and β-PbO for direct conversion imaging. Scientific reports. 2017;7(1):1-0. [43] Zhao M, Yi D, Camino G, Frache A, Yang R. Interdigitated crystalline MMT–MCA in polyamide 6. RSC advances. 2017;7(2):861-9. [44] Elmer P. Thermogravimetric analysis (TGA) a beginner 0 s guide. United States of America: Perkin Elmer. 2010. [45] Mahmoud ME, El-Khatib AM, Badawi MS, Rashad AR, El-Sharkawy RM, Thabet AA. Fabrication, characterization and gamma rays shielding properties of nano and micro lead oxide-dispersed-high density polyethylene composites. Radiation Physics and Chemistry. 2018; 145:160-73. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major revision 18 Apr, 2022 Reviews received at journal 10 Apr, 2022 Reviews received at journal 15 Mar, 2022 Reviewers agreed at journal 10 Mar, 2022 Reviewers invited by journal 09 Mar, 2022 Editor assigned by journal 09 Mar, 2022 Editor invited by journal 22 Dec, 2021 Submission checks completed at journal 22 Dec, 2021 First submitted to journal 16 Dec, 2021 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-1176766","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":71879116,"identity":"aa4d4127-aa0b-4e05-819a-a04e39302a99","order_by":0,"name":"Shahryar Malekie","email":"","orcid":"","institution":"Nuclear Science and Technology Research Institute","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shahryar","middleName":"","lastName":"Malekie","suffix":""},{"id":71879119,"identity":"60e75916-d1d4-43da-bab0-7b2b45ad0567","order_by":1,"name":"Hassan Shooli","email":"","orcid":"","institution":"Islamic Azad University Arsanjan Branch","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hassan","middleName":"","lastName":"Shooli","suffix":""},{"id":71879121,"identity":"aeb0c739-25ad-4916-9674-9bcfc664bf36","order_by":2,"name":"Mohammad Amin Hosseini","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5UlEQVRIiWNgGAWjYBACAyjJA6Y/oIkT1sI4g3gtUMDMQ4zDzNnbH3/4UHBHhoH/dOJnmz+Ho+UbmB9+YCi4h1OLZc8ZM8kZBs94GCRyN0vnth3O3XCAzViCwaAYt8Nu5LAx8xgcBmrh3SCd2wDUwsBgBhRPwKMl/fHnPyAt/Gc3/7b4czh3fgP7NwJaEgykGUBaGHK3STOwHc5tOMBDwJYzQL/0gB2Wu82yty09d8NhnmKJBHxajgND7Mefw/Ygh9348cc6d357+8YPH/7g1gIH9gdgLGYgJkLDKBgFo2AUjAI8AACzmlEEWJtjEwAAAABJRU5ErkJggg==","orcid":"","institution":"Shiraz University of Medical Sciences","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Mohammad","middleName":"Amin","lastName":"Hosseini","suffix":""}],"badges":[],"createdAt":"2021-12-16 08:59:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1176766/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1176766/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":16804029,"identity":"0588124d-515e-45ce-ab9c-0bd7fce0369f","added_by":"auto","created_at":"2021-12-28 17:42:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":446617,"visible":true,"origin":"","legend":"\u003cp\u003eThe geometric arrangement used to experimentally evaluate attenuation in the samples. The lead cylinder for narrowing the beams, the detector probe, the power supply, and the spectrum measured by the software are shown in this figure.\u003c/p\u003e","description":"","filename":"fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/1e6f57650e85c6b03be99a87.png"},{"id":16804025,"identity":"ac4a92e6-fde9-4b4b-9c3f-c0150f7a10c0","added_by":"auto","created_at":"2021-12-28 17:42:06","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":151416,"visible":true,"origin":"","legend":"\u003cp\u003eThe output curves of the detector system in the presence of an Americium (Am-241) source. The first peak represents the Compton scattering, and the second peak (located between channels 100 and 200) is the main curve for measuring the radiation intensity. The diagram shows how linear regression was used to calculate the linear attenuation coefficients.\u003c/p\u003e","description":"","filename":"fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/cb2510d6a1b51f8ed2bf74a5.png"},{"id":16804027,"identity":"b22a36e8-bb2c-4bfc-ad94-e3037cc8b1ad","added_by":"auto","created_at":"2021-12-28 17:42:06","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1003248,"visible":true,"origin":"","legend":"\u003cp\u003eThe SEM images of the samples at different magnifications: (\u003cstrong\u003eA1, A2\u003c/strong\u003e) PbO, (\u003cstrong\u003eB1, B2\u003c/strong\u003e) PA6, (\u003cstrong\u003eC1, C2\u003c/strong\u003e) PA6/PbO-5%, \u003cstrong\u003e(D1, D2\u003c/strong\u003e) PA6/PbO-10%, (\u003cstrong\u003eE1, E2\u003c/strong\u003e) PA6/PbO-20%, and (\u003cstrong\u003eF1, F2\u003c/strong\u003e) PA6/PbO-50%.\u003c/p\u003e","description":"","filename":"fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/c6b8533944eb9890e36f9448.png"},{"id":16804026,"identity":"5f8eeee6-0300-4832-93db-4822cf1adaaa","added_by":"auto","created_at":"2021-12-28 17:42:06","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":41056,"visible":true,"origin":"","legend":"\u003cp\u003eThe EDX spectrum of PA6/PbO-10% composite.\u003c/p\u003e","description":"","filename":"fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/d7b7cfb72379eb91e142e17d.png"},{"id":16804208,"identity":"c220e61e-268e-4536-ada7-c5fd932df3bc","added_by":"auto","created_at":"2021-12-28 17:45:06","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":414377,"visible":true,"origin":"","legend":"\u003cp\u003eThe XRD graphs of the PA6/PbO composites at various concentrations of the fillers, (A) 0 wt% (pure PA6), (B) 5 wt%, (C) 10 wt%, (D) 20 wt%, and (E) 50 wt%.\u003c/p\u003e","description":"","filename":"fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/81e8921f91f02c214c4f0fc5.png"},{"id":16804032,"identity":"c05a08b2-6735-4d1a-b2fb-6470b2d159ba","added_by":"auto","created_at":"2021-12-28 17:42:06","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":561153,"visible":true,"origin":"","legend":"\u003cp\u003eAnalytical TGA and DTG graphs for (A) crude PA6, (B) PA6/PbO-10%, and (C) PA6/PbO-20%.\u003c/p\u003e","description":"","filename":"fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/4075d94c606896bf698028f5.png"},{"id":16804031,"identity":"b64feea8-0efc-433b-b24b-d89fae51e747","added_by":"auto","created_at":"2021-12-28 17:42:06","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":171750,"visible":true,"origin":"","legend":"\u003cp\u003eThe trend of changes in the mass attenuation coefficients in a broad energy range for the five studied composites.\u003c/p\u003e","description":"","filename":"fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/32199ddb3fa85697e7364cc2.png"},{"id":16804207,"identity":"d4bca310-7844-4ad9-a5ec-fb1e06387888","added_by":"auto","created_at":"2021-12-28 17:45:06","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":151636,"visible":true,"origin":"","legend":"\u003cp\u003eThe measured HVL values for the five composites studied at energy intensities of 59 and 662 keV.\u003c/p\u003e","description":"","filename":"fig8.png","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/a7cdbf39d259e98dfb37e7ae.png"},{"id":16804209,"identity":"e9fe8a49-8915-48f4-8b70-04a67202b144","added_by":"auto","created_at":"2021-12-28 17:45:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":972903,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1176766/v1/66914dbc-b997-47a2-886e-e978626e6ee9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assessment of New Composites Containing Polyamide-6 and Lead Monoxide as Shields against Ionizing Photonic Radiation based on Computational and Experimental Methods","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eToday, the risk of intended or unintended exposure to ionizing radiation has increased in humans due to their increasing tendency to develop and use new technologies [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Some of the causes of exposure to ionizing radiation include cosmic rays, fuel processing, nuclear fusion processes, industrial radiation processing (especially in the food and health sectors), and long-term use of X-rays and gamma rays for diagnostic and therapeutic purposes [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Despite these advantages, radiation hazards and protection remain serious health concerns [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe use of adsorbents for the development of protectants is a well-known strategy. Lead, as an element best known for its high atomic number, shows high efficiency in absorbing radiation. Besides, due to its high abundance and cost-effectiveness, major attention has been paid to this element. For many years, lead products have been the best available option for fabricating fixed (e.g., walls and blocks) or portable (e.g., aprons, glasses, gloves) protection equipment [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. However, the challenges and problems of using lead products have become more prominent over time. Today, the disadvantages of using bulk lead in the construction of shields have been addressed, such as the high weight of lead products, health and environmental challenges due to high lead toxicity, and high fragility of these products [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn recent years, different approaches have been employed to obviate the mentioned challenges. The use of materials, such as bismuth, tungsten, and tin as alternatives to lead, is one of these well-known approaches [\u003cspan additionalcitationids=\"CR7 CR8 CR9\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. It seems that application of a novel method involving the use of nanocomposites can resolve many of these challenges. In this method, a combination of polymers (matrix) and nanoscale heavy metals (fillers) is often used. It is assumed that with a suitable distribution of particles in the matrix, the surface -to-volume ratio increases, leading to a higher radiation absorption efficiency and an optimal reduction in the product size [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Therefore, in this method, the radiation protection products are expected to have higher efficiency, flexibility, chemical and thermal stability, and biocompatibility [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the mentioned disadvantages for lead, previous studies have reported promising results by using nanosize or microscale lead (rather than bulk use) with various chemical structures (e.g., PbO, PbO2, Pb3O4, or chloride forms). Overall, these approaches provide an opportunity to optimize the use of lead in new forms [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. So far, numerous experimental studies have been conducted on the applicability of lead polymers for radiation protection. Different concentrations of lead monoxide (PbO) have been assessed in unsaturated polyesters with a \u0026zwj;cesium-137 source [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] by adding modified nanoclay [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSatisfactory radiation protection efficiency and structural properties have been reported, based on the comparison of bulk and nanoscale PbO features in heavy polyethylene [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] or a linear low density polyethylene in exposure to mid- and high-energy gamma radiation [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], besides other compounds, such as nano-PbO reinforced into epoxy resins [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], polyvinyl alcohol [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and polyesters [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In line with experimental studies, several other studies using computational methods have confirmed the efficiency of lead-based composites [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Moreover, polymer-based composites and nanostructures have shown unique features in other radiation fields, including the basic design and development of ionizing radiation dosimeters [\u003cspan additionalcitationids=\"CR22 CR23 CR24 CR25 CR26\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the reported benefits of polymeric composites in ionizing radiation and the possibility of reusing optimized lead composites as radioprotective materials, there is a need for further scientific research on these composites. Therefore, in the present study, new composites, consisting of PbO and polyamide-6 (PA6), were fabricated, and protection against X-rays and gamma rays was investigated in a broad energy range, using computational and experimental methods. To the best of our knowledge, this is one of the first reports on composites containing lead fillers in a polymeric PA6 matrix.\u003c/p\u003e"},{"header":"2. Materials And Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Theoretical section: Estimation of radiation attenuation properties of the compounds\u003c/h2\u003e \u003cp\u003eThis study primarily aimed to assess the protective effects of novel PA6/PbO composites against X-ray and gamma radiation, using computational approximation and experimental methods. The studied composites contained PbO (ρ\u0026thinsp;=\u0026thinsp;9.53 g/cm\u003csup\u003e3\u003c/sup\u003e) as the filler and PA6 ([C\u003csub\u003e12\u003c/sub\u003eH\u003csub\u003e22\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e, ρ\u0026thinsp;=\u0026thinsp;1.13 g/cm\u003csup\u003e3\u003c/sup\u003e) as the polymeric matrix [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. In this study, five composites containing different weight percentages of PbO (0, 5, 10, 20, and 50%) were fabricated. Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the distribution of elements in each compound. The nominal density of each compound was calculated, based on the American Society for Testing and Materials (ASTM) D792-91 standard (1991) (the last column of Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), using the following formula [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\rho =\\frac{1}{\\frac{{w}_{1}}{{\\rho }_{1}}+\\frac{{w}_{2}}{{\\rho }_{2}}} \\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003ew\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eρ\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e denote the weight percentage and density of the fillers (i.e., PbO), respectively, and \u003cem\u003ew\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eρ\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e represent the corresponding parameters for the matrix (i.e., PA6), respectively.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCharacteristics of the studied composites consisting of five different combinations of PA6 and PbO.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ewt% (PbO)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eρtotal (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePA6 (crude)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.098\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.637\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.124\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.141\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.130\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePA6/PbO-5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.093\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.605\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.118\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.138\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.182\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePA6/PbO-10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.088\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.573\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.134\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.093\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.239\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePA6/PbO-20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.078\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.509\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.099\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.127\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.186\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.372\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePA6/PbO-50%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.064\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.417\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.081\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.117\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.320\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e2.020\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eMoreover, it is possible to approximate the radiation absorption and attenuation properties of materials and compounds both before and after synthesis, based on calculations using the dedicated codes and programs. Besides, experimental analysis of attenuation and absorption properties in a wide range of beam energies, which is by itself an interesting research topic, has limitations in practice. Therefore, use of dedicated software programs, followed by validation of the results using experimental tests in exposure to several radioactive sources (i.e., comparison of the results of experimental and computational methods), has always been interesting to researchers [\u003cspan additionalcitationids=\"CR31 CR32\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Some important parameters for estimating the behavior of materials in exposure to X-rays and gamma rays include the linear attenuation coefficient (\u0026micro;L), total mass attenuation coefficient (\u0026micro;/ρ), and half-value layer (HVL), which are measured with dedicated Monte Carlo codes and software programs. One of the well-known dedicated programs is XMuDat [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e], which can measure parameters, such as the mass attenuation coefficient, for six different compounds simultaneously in a broad photon energy range (0.001-50 MeV). In this program, it is essential to include the content of each compound (e.g., type of elements and weight percentages). Calculations are performed according to the algorithms in the program and the data of a reference library. It is possible to use one of the two references by Hubbell et al. [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] or Boone et al. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] as default calculations,\u003c/p\u003e \u003cp\u003ewhere the mass attenuation coefficients of different elements (Z=1-92) at different energy levels are described. The total mass attenuation coefficient (\u0026micro;/ρ\u003csub\u003etotal\u003c/sub\u003e) of every compound at any given energy level was calculated using the following formula:\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$({\\frac{\\mu }{\\rho })}_{total}=\\sum {w}_{i}\\times ({\\frac{\\mu }{\\rho })}_{i} (2)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003ew\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e is the weight fraction of each element in the compound, and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(({\\frac{\\mu }{\\rho })}_{i}\\)\u003c/span\u003e\u003c/span\u003e represents the total mass attenuation coefficient (measured by dividing the linear attenuation coefficient [\u0026micro;L] by the element density [ρ] at the designated energy level) [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. It is possible to obtain these numerical values and standard graphs in the software for a maximum of six compounds. By determining the final \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(({\\frac{\\mu }{\\rho })}_{total}\\)\u003c/span\u003e\u003c/span\u003e value at the specified energy level and considering the density of the composite, the HVL value was determined as follows [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]:\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$HVL=\\frac{ln2}{{\\mu }_{L}} \\left(3\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the present study, the numerical values for the total mass attenuation of the five samples, listed in Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, were calculated in XMuDat. The input information for the program included data, such as the type and weight fraction of the elements (Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Calculations were performed based on the data library reported by Boone et al. for photon emissions in an energy range of 0.001-10 MeV.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Experimental Section\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1. Materials and equipment for characterization of the samples\u003c/h2\u003e \u003cp\u003ePolyamide 6 (PA6)-Akulon\u0026reg; F223-D (DSM products) was purchased from the market. Nanoscale PbO powder (in form of a 25-g stock solution) was purchased from Aria Chemical Co. (Tehran, Iran) and used in experiments after its qualification was verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM) examinations. The following characterization tests were carried out on the PA6/PbO composites: SEM (TESCAN MIRA3, Czech Republic); thermogravimetric analysis (TGA) over a temperature range of 20-600\u0026deg;C at a rate of 10\u0026deg;C/min in air using a TGA analyzer (Netzsch TG 209F3 Tarsus, Frankfurt, Germany); and XRD analysis for phase detection (X'Pert PRO MPD, PANalytical, Almelo, Netherlands). All analyses were performed at room temperature. The X-ray radiation parameters were set at 40 kV and 30 mA (target=Cu Kα, λ\u0026thinsp;=\u0026thinsp;1.54 \u0026Aring;). It should be noted that in this system, the scans were acquired over a 2θ angle range of 1\u0026deg; to 100\u0026deg; (with 0.026\u0026deg; intervals) in a counting time of 0.5 sec. All of the three mentioned examinations were performed at Razi Metallurgical Research Center (Alborz, Iran) as a service provider.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2. Fabrication of PA6/PbO composites\u003c/h2\u003e \u003cp\u003eThe fabrication of five PA6/PbO composites, including different weight percentages of PbO filler (0, 5, 10, 20, and 50%), was initiated by the melt-mixing method. The final fabrication and preparation phases were conducted, using hot and cold pressing processes. During the synthesis process, PA6 and PbO powders were initially weighed, based on the predetermined mass ratios on a four-point digital scale (CAS model) and then placed in an oven at 90\u0026deg;C for several hours to ensure dehumidification. Before synthesis, granulated PA6 particles were exposed to liquid nitrogen for ten minutes to reaffirm their dryness and fragility. Next, an ultra-centrifugal mill (ZM 200, Retsch, Germany) was used at 14,000 rpm to reduce the particle size to 50 \u0026micro;m.\u003c/p\u003e \u003cp\u003eConsidering the melting point of polyamide, the samples were synthesized in a laboratory mixing extruder (Dynisco, USA) over a temperature range of 220-245\u0026deg;C at 50 rpm. The synthesis conditions were set based on the operator\u0026rsquo;s experience and a previous study [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Finally, the materials were formed into galvanized sheet molds with dimensions of 8\u0026times;8\u0026times;0.1 cm\u003csup\u003e3\u003c/sup\u003e. For molding, the synthesized materials were initially poured into molds and then formed by hot and cold pressing machines (Toyo Seiki Co., Japan). For this purpose, first, hot pressing was performed for each sample at an approximate temperature of 240\u0026deg;C, considering the melting point of polyamide, less than 25 kg/cm\u003csup\u003e2\u003c/sup\u003e pressure for five minutes. Next, a cold pressing machine, the plates of which were being cooled by water spray, was applied immediately at a similar pressure for three minutes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3. Experimental analysis of radiation attenuation\u003c/h2\u003e \u003cp\u003eThe linear attenuation coefficients (\u0026micro;L) of the samples were measured, using an experimental method according to a previous report [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] over a descending photon energy range with a narrow-parallel beam geometry. After the synthesis and molding of the fabricated samples, they were subjected to experimental radiation tests. First, the sheet composites, with dimensions of 8\u0026times;8\u0026times;0.1 cm\u003csup\u003e3\u003c/sup\u003e, were cut into four sections. To determine the experimental linear attenuation coefficients and HVL values of the composites, a narrow-parallel geometry was considered (Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) in the presence of two standard low-energy (\u003csup\u003e241\u003c/sup\u003eAm, Eγ\u0026thinsp;=\u0026thinsp;0.059 MeV) and medium-energy (\u003csup\u003e137\u003c/sup\u003eCs, Eγ\u0026thinsp;=\u0026thinsp;0.662 MeV) gamma-ray sources.\u003c/p\u003e \u003cp\u003eThe experiments were performed in a specialized laboratory for Secondary Standard Dosimetry Laboratory (SSDL) in Karaj, Iran. For the experimental radiation tests (Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), a calibrated detector, equipped with a CsI(Tl) cylindrical probe (NT-812), was used. The instrument was connected to a power supply and an amplifier (Novin-Teyf, Iran), as shown in Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. For the initial narrowing of beams, a hole was created in parallel with the probe axis on the lid of the cylindrical chamber, where the standard radiation source was placed (Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo measure the radiation intensity at the desired energy level, the output spectrum of the detector was initially measured in the presence of the test material with different thicknesses (t=1-4 mm) or in its absence (t=0). Next, the areas under the curve at the specified peaks (Figure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), corresponding to the measured energy intensities (I\u003csub\u003e0\u003c/sub\u003e, I\u003csub\u003e1\u003c/sub\u003e, I\u003csub\u003e2\u003c/sub\u003e, I\u003csub\u003e3\u003c/sub\u003e, and I\u003csub\u003e4\u003c/sub\u003e) in different layers, were used to determine the linear attenuation coefficients, based on the Beer-Lambert formula [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]:\u003cdiv id=\"Equd\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equd\" name=\"EquationSource\"\u003e\n$${\\mu }_{L}=\\frac{\\text{ln}\\left(\\frac{{I}_{0}}{I}\\right)}{t} \\left(4\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe net value of the linear attenuation coefficient for each sample at a specific energy level was determined by analyzing the linear regression, as shown in Figure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; the curve slope corresponds to the linear attenuation coefficient. After determining the experimental value of the linear attenuation coefficient, the HVL value can be calculated at each energy level using \u003cb\u003eEquation 3\u003c/b\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4. Results \u0026 Discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e4.1. Morphological analysis of the samples by SEM\u003c/h2\u003e \u003cp\u003eThe pre-synthesis SEM micrographs of PbO powder, samples containing 5, 10, 20 and 50 wt% of PbO, and lead-free sample (crude PA6) are shown in Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. To better understand the distribution of particles, images were acquired at two different magnifications. Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA (\u003cb\u003eA1, A2\u003c/b\u003e) shows PbO powder before synthesis, with different particle sizes (reaching even \u0026lt;100 nm). Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB \u003cb\u003e(B1, B2\u003c/b\u003e) presents the crude PA6 (filler matrix), allowing for a better assessment of the filler distribution; it seems that the polyamide matrices are arranged as sheets next to each other, similar to microfibers.\u003c/p\u003e \u003cp\u003eMoreover, the filler distribution at weight percentages of 5% and 10% in PA6 after hot and cold pressing processes is presented in Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC \u003cb\u003e(C1, C2)\u003c/b\u003e, Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD \u003cb\u003e(D1, D2)\u003c/b\u003e respectively. The nano-PbO particles showed a relatively consistent distribution on the polymer surface. However, a slight increase was observed in the filler size, using 10 wt% filler due to the accumulation of particles. Likewise, by increasing the filler weight percentage to 20% and 50%, the asymmetrical increase in the filler size became more noticeable on the surface (\u003cb\u003eE1, E2 \u0026amp; F1, F2\u003c/b\u003e); this increase was even more noticeable than that observed in fillers with lower weight percentages.\u003c/p\u003e \u003cp\u003eDespite the accumulation of filler particles in both 20% and 50% PbO composites, 20% PbO seemed to have a more symmetrical distribution on the polymer surface. However, in the 50% PbO sample, an increase in the filler percentage and high adhesion between the filler particles resulted in the accumulation of particles with asymmetrical sizes. In other words, as shown in Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eF \u003cb\u003e(F1, F2)\u003c/b\u003e, the agglomerations of the fillers were more significant at this concentration, reflecting the formation of stronger van der Waals forces among filler particles, with an increase in the weight percentage of heavy metal fillers (e.g., lead and bismuth) dominating the filler-polymer bonds [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. This finding is consistent with the previous studies in composites, containing lead at a weight percentage of 20% or higher [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo assess the quality of elements on the surface of the composites, an energy-dispersive X-ray (EDX) analysis was performed on the sample containing 10% lead (Figure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). As can be seen, the absorption edges of lead (Mα and Mβ) and other elements, such as carbon and oxygen (Kα), emerged as fingerprints within the selected energy range, confirming the presence of lead (as filler) in the synthesized samples. It should be noted that the absence of hydrogen, as a light element, is related to the inherent limitations of this analytical test [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e4.2. Results of XRD analysis of PbO-containing composites\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e presents the results of XRD analysis of the studied composites containing different filler weight percentages (5, 10, 20, 30, and 50 wt%) in the PA matrix at different intensities over different 2\u0026#120579; angles. The observed XRD pattern indicated the following results:\u003c/p\u003e \u003cp\u003e1) The peaks observed in the first region, especially at 20.26\u0026deg; and 23.5\u0026deg; angles, were detected in all samples; according to previous studies, these peaks belonged to PA6 [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Gupta et al., besides mentioning the possible formation of two alpha and gamma crystalline phases in PA6, conducted phase detection by XRD analysis at different temperatures and observed similar peaks at 240\u0026deg;C (similar to our results), which were attributed to the dominance of the alpha phase over the gamma phase in PA6. They also observed the superiority of the alpha phase over the gamma phase in terms of thermodynamic stability [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e], which is a favorable feature of the composites investigated in the present study.\u003c/p\u003e \u003cp\u003eOn the other hand, following phase extraction, the samples showed a red color in the graphs. After analysis and matching with the Joint Committee on Powder Diffraction Standards (JCPDS) cards, the Massicot cards (card No. 4747-338 and 05-0570) were also identified. According to previous studies, PbO is present in two crystalline phases of α-PbO and β-PbO [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. While the alpha phase is tetragonal, the beta phase (i.e., Massicot) has an Orthorhombic shape with unequal sides. Also, in the graphs, the geometric dimensions of each sample are well characterized (a=5.4, b=4.7, c=5.8 \u0026amp; α\u0026thinsp;=\u0026thinsp;β\u0026thinsp;=\u0026thinsp;γ\u0026thinsp;=\u0026thinsp;90\u0026deg;).\u003c/p\u003e \u003cp\u003e2) In addition to the abovementioned peaks, flattening of the primary regions (2\u0026#120579; angle\u0026lt;10\u0026deg;) was also noticeable in the XRD graphs; this region is clearly visible in Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA (crude PA6 sample). With an increase in the filler weight percentage, this area became smaller, and it was hardly visible at the highest filler weight percentage (Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD). Meanwhile, enhanced peak intensities at other angles (2\u0026#120579; angle\u0026asymp;20.26\u0026deg;, 23.5\u0026deg;, and 29.1\u0026deg;) could indicate more crystallization of the composites by increasing the weight percentage of lead (in exchange for a decrease in the amorphous region). Nevertheless, increasing the filler weight percentage did not introduce tangible changes in the dominant shape or other parameters of the lattice.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.3. Thermal analysis of composites\u003c/h2\u003e \u003cp\u003eThe thermal stability analysis of the three selected compounds, including crude PA6 and composites containing 10 and 20 wt.% PbO, was conducted, using a thermogravimetric analysis (TGA) and a differential thermal analysis (DTA); the results are presented in Figure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The analyses were performed under N\u003csub\u003e2\u003c/sub\u003e atmosphere in a temperature range of 20-600\u0026deg;C (at a heating rate of 10\u0026deg;C/min), according to the ASTM E1131-08 standard (2014).\u003c/p\u003e \u003cp\u003eThe TGA curves revealed multi-phase trends in the mass changes of all composites, but at different intensities. For example, in the crude PA6 sample, the mass reduction was less than 10% before reaching a temperature of 400\u0026deg;C, corresponding to a continuous glass transition in the DTA diagram; this trend is completely compatible with previous reports [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. It should be noted that the mass change in this region was attributed to a reduction in moisture and dehumidification of the sample [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. On the other hand, the mass change trends of samples containing 10 and 20 wt% lead were observed in the same area at a lower temperature, indicating a shift toward a lower glass transition temperature by increasing the filler weight percentage. The rates of mass reduction by increasing the lead concentration were 15.5% and 22.7%, respectively. In line with our observations, another study attributed this trend to the increased aggregate formation by the filler in the composite [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eConsidering the trend of changes in the curves by increasing the temperature, the next round of decomposition occurred over a temperature range of 440-442\u0026deg;C, where a sharp weight loss was clearly observed in all DTA graphs. The weight loss percentages compared to the initial peak were 90.5%, 66%, and 54% for the crude PA6, 10% lead-containing composite, and 20% lead-containing composite, respectively. Sharp changes in this area (known as the melting zone) can be attributed to chemical decomposition due to the loss of CO\u003csub\u003e2\u003c/sub\u003e by the samples in this thermal range [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. As can be seen in all three graphs, at the final temperature point (600\u0026deg;C), the residual masses were 1%, 8%, and 13.5% for the crude PA6, 10% lead-containing composite, and 20% lead-containing composite, respectively. Based on these observations, increasing the percentage of lead filler led to a reduction in weight loss and a boost in the thermal stability of the studied PA6/PbO composites.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e4.4. Results of gamma-rays attenuation on the samples\u003c/h2\u003e \u003cp\u003eThe mass attenuation coefficients (\u0026micro;/ρ) of the five studied composites were calculated in XMuDat. For a better understanding of this phenomenon, the trends were assessed in a photon energy range of 1-10,000 keV, as shown in Figure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Figure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, by increasing the energy level, the crude PA6 showed a slight gradual reduction in the attenuation coefficient. However, the stepwise addition of PbO up to 50% of the composite weight resulted in an increase in the attenuation coefficient, which is especially evident in the low- and medium-energy ranges (1-500 keV). Besides, the curve analysis of lead-containing composites showed a sudden noticeable drop in the mass attenuation coefficient in low-energy regions (\u0026lt;100 keV) compared to higher-energy zones. The sharp peaks observed in this area might indicate the dominance of photoelectric effects at some energy levels (e.g., 88 keV and 15 keV for K- and L-absorption edges of lead, respectively) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Based on these results, an increase in the weight percentage of lead offers a more optimal attenuation in the mentioned energy range.\u003c/p\u003e \u003cp\u003eTable \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e presents the linear attenuation coefficients calculated by XMuDat program and the experimental method at two energy levels of 59 and 662 keV. By increasing the lead oxide filler weight percentage, the attenuation trend improved, as evidenced by an increase in the mass attenuation coefficients. Despite differences in the values obtained by these two approaches, an acceptable agreement was observed between the experimental and computational data; also, these differences depended on the concentration of lead. The difference observed between the computational and experimental data may be partly explained by differences in the distribution of elements in the samples. In other words, in computational programs, such as XMuDat, elements are considered to be uniformly distributed in the samples (i.e., a uniform filler distribution in the matrix). However, in reality, as shown in SEM images (Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), this distribution is not necessarily uniform and may be accompanied by the formation of agglomerations, which is more evident at a weight percentage of 50%. The importance of this factor in the agreement of computational and experimental data has been highlighted in a similar study [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMoreover, to better understand the experimental results, a comparison with the findings of three experimental studies on similar PbO concentrations is presented in Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (columns 4 to 6). As can be seen, the experimental data of the present and previous studies were consistent for PbO weight percentages up to 20%; however, differences were still evident at the highest weight concentration (50%), associated with numerous aggregates.\u003c/p\u003e \u003cp\u003eDespite the abovementioned findings, some errors in the experimental method cannot be overlooked, such as errors in the geometrical arrangements, causing scattered beams to reach the detector, besides deviation from an ideal geometry. This issue is particularly important at lower energies (i.e., 59 keV in the present study). Besides, other errors are possible, such as detector errors (e.g., dead time). Despite similar filler concentrations in the studies described in Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, different polymeric matrices were used in these studies. Harish et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] used unsaturated polyester (1.2 g/cm\u003csup\u003e3\u003c/sup\u003e); Bagheri et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] used unsaturated polyester plus 5% nanoclay filler; and Mahmoud et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] used a high-density polyethylene (0.953 g/cm\u003csup\u003e3\u003c/sup\u003e). These differences caused slight variations in the amount and type of elements in the products and consequently led to variable degrees of attenuation. As the final density of the product seems to affect the radiation attenuation [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], accurate measurement of the final density of materials can somehow explain the observed differences.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe linear attenuation coefficients measured in the present study using the computational and experimental methods compared to the results of similar previous studies\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePbO wt%\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCalculated by XMuDat\u003c/p\u003e \u003cp\u003e(this study)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExperiments\u003c/p\u003e \u003cp\u003e(this study)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHarish et al. 2008\u003c/p\u003e \u003cp\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBagheri et al. 2018\u003c/p\u003e \u003cp\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMahmoud et al. 2018\u003c/p\u003e \u003cp\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eE=662 (keV)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0997\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.089\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.091\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.105\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.123\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.130\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1264\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.119\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.196\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.140\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.206\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.189\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eE=59 (keV)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.496\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.605\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.599\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.555\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.050\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.130\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.050\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.488\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFinally, the gamma radiation attenuation improved by increasing the weight percentage of the lead oxide, as evidenced by the measured HVL values (Figure \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). By increasing the weight percentage of the lead oxide from 0% (crude polyamide) to 50%, the HVL value decreased from 3.13 to 0.17 cm at energy intensity of 59 keV and from 7.28 to 4.97 cm at an energy intensity of 662 keV. In other words, by increasing the energy and penetrating depth of gamma rays, the thickness required to block half of irradiated gamma rays also increased.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"5. Discussion","content":"\u003cp\u003eIn recent years, due to the increasing demand of ionizing radiation in various industries and medicine, the importance of protection against radiation has increased. In this regard, polymeric composites, as novel alternatives to traditional materials, have been proposed for designing protective shields and addressing the challenges of conventional methods [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Previously, polymeric composites offered satisfactory results for the fabrication and design of radiation dosimeters [\u003cspan additionalcitationids=\"CR22 CR23 CR24 CR25 CR26\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe disadvantages of using bulk amounts of lead for constructing radiation protectants include high toxicity, environmental pollution, undesirable mechanical stability, and high weight of lead products (due to high lead density). However, due to its high atomic number, wide availability, and most importantly, its capacity to transform into micro- and nano-dimensions (in various chemical forms) promise the optimized reuse of lead, which has shown satisfactory results in the previous studies [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the present study, new PbO/PA6-based composites, consisting of different weight percentages of PbO (0, 5, 10, 20, and 50%), were fabricated and then characterized using both computational (XMuDat program) and experimental (characterization and experimental tests) methods. According to the computational analyses (Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), before the synthesis of composites, lead-containing samples were predicted to show better attenuation compared to lead-free samples (crude PA6). By increasing the weight percentage of PbO, the attenuation trend improved, as evidenced by an elevation in the mass attenuation coefficients. This finding was more evident (as peaks) at energy intensities of 15 and 88 KeV, which represent the K- and L-absorption edges of lead and indicate the predominance of the photoelectric effect in these composites [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. It seems that in diagnostic procedures, such as radiology and nuclear medicine, these composites can be effective in protection against radiation.\u003c/p\u003e \u003cp\u003eIn the experimental section of this study, the composites were initially fabricated and then characterized. For this purpose, the melt-mixing method, which is a cost-effective and relatively convenient method, was used to synthesize the samples in an extruder. The required adjustments in the device, such as temperature (based on the melting point of PA6), rotation speed and duration, were set based on the operator\u0026rsquo;s experience and the results reported in a study by Mahmoud and colleagues [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The experiments were conducted in a specialized laboratory for fabricating plastics and polymers.\u003c/p\u003e \u003cp\u003eThe characterization of the samples based on SEM showed that up to a filler weight percentage of 20 wt%, there was a relatively symmetrical distribution of PbO particles in the polyamide; however, by increasing the weight percentage, the filler started to form aggregations that were seen as large lumps at the highest weight percentage (50%). In the EDX analysis of a selected sample, the fingerprints of lead and a number of other elements in the composites were observed (Figure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). To explain the increasing accumulation of filler particles, Mehrara et al. referred to the formation of strong van der Waals forces among filler particles, dominating the filler-polymer bonds [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. This observation is consistent with previous reports on other lead-containing composites with similar weight percentages [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. It should be noted that in this study, for the first time, a SEM image of a sample containing 50% lead oxide was acquired.\u003c/p\u003e \u003cp\u003eThe phase detection and evaluation of the crystal network of the composites via XRD showed that PA6 was in the form of alpha crystals in the samples. Previous studies have reported that this type of polyamide is sensitive to temperature and may form different phases upon thermal changes [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. In this study, the emergence of peaks at 20.26\u0026deg; and 23.5\u0026deg; angles indicated the predominance of the alpha phase, which might be attributed to the sample synthesis and pressing processes at temperatures approximating 240\u0026deg;C. Besides, by increasing the filler weight percentage, the flattening of initial zones (2\u0026#120579; angle\u0026lt;10\u0026deg;; amorphous zone) started to decrease, whereas greater sharpness and more crystallization were observed at angles corresponding to PbO. This finding was also confirmed after matching with the JCPDS standard cards and detection of the Massicot phase (lead mineral form) (codes 4747-1387 and 05-0570, respectively) (Figure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). These observations are in agreement with previous studies [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the current study, thermal stability was assessed using the TGA and DTGA analyses in three samples (crude PA6 and composites containing 10% and 20% lead oxide, respectively). In the crude PA6 sample (Figure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA), before reaching a temperature of 400\u0026deg;C, there was a relatively smooth and continuous glass transition, which could be attributed to the dehumidification of the sample [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]; it should be noted that for samples containing a lead oxide filler (Figure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB \u0026amp; \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eC), the glass transition temperatures were lower (359\u0026deg;C and 347\u0026deg;C for 10% and 20% filler weight percentages, respectively). A similar trend was also observed in a previous study [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], which could be attributed to the presence of lumps and deformation in the mentioned temperature range. By increasing the temperature and reaching the melting zone, the superiority of lead-containing samples was supported by their less significant weight loss. This superiority remained noticeable until the end-point temperature (600\u0026deg;C) and was verified by the quantitative assessment of the residual mass. Therefore, it can be concluded that increasing the lead filler ratio in the composites caused them to lose less weight and acquire higher thermal stability.\u003c/p\u003e \u003cp\u003eIn the second section of the experimental analyses, the radiation attenuation trends for photon sources were assessed at 59 keV (low energy) and 660 keV (medium energy) in the lead-containing samples in a specialized laboratory. Notably, the results of this section were consistent with the theoretical results for lower filler weight percentages. To explain this finding, it should be noted that in the computational method, it is assumed that the samples have a homogeneous distribution of elements; therefore, in practice, samples with less formation of lumps showed a better agreement with the computational data. On the other hand, significant differences were observed in samples with a higher filler percentage (e.g., 50%) due to the formation of numerous lumps. A comparison between our experimental results and those of previous studies (Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), indicating a slight difference in the reported experimental data, can also confirm this finding.\u003c/p\u003e \u003cp\u003eIn this regard, Mahmoud et al. (2020), by examining lead filler weight percentages up to 10%, reported a good agreement between the experimental and computational data due to the uniform distribution of the filler [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. According to our experimental results, by increasing the weight percentage of lead from 0% (crude PA6) to 50%, the HVL values decreased from 2.13 to 0.17 cm at an energy level of 59 kV and from 7.21 to 4.97 cm at an energy level of 662 keV.\u003c/p\u003e \u003cp\u003eThis study had some limitations, based on which we have made some suggestions for future studies. Considering the acceptable efficiency of the composites containing lead up to a weight percentage of 20%, composites with other lead weight percentages (20\u0026ndash;50%) can be assessed in future experiments. In this study, thermal stability was investigated in only three samples; it is advisable to extend this analysis to other samples, as well. Finally, further experimental analysis of the radiation attenuation and absorption capacity of PbO/PA6 composites can be performed at other energy levels to verify the protective efficiency of these composites. To the best of our knowledge, this study on PA6/PbO composites is among the first reports on these novel radioprotectants; therefore, further investigation is strongly recommended.\u003c/p\u003e"},{"header":"6. Conclusion","content":"\u003cp\u003eWe studied the applicability of novel PA6/PbO-based composites, containing different weight percentages of PbO (0, 5, 10, 20, and 50%) as protectants against X-ray and gamma rays, using both computational and experimental methods. The composites were synthesized in a laboratory mixing extruder and characterized by various tests, including SEM, XRD, TGA, and experimental radiation tests. The SEM images showed the acceptable symmetrical distribution of PbO particles (weight percentages up to 20%) in PA6. Moreover, an increase in the formation of crystalline networks, along with decreased amorphous zones in the composites, was observed by increasing the filler weight percentage, as evidenced by the XRD analysis. Besides, a thermal analysis was conducted for the selected samples, containing 0%, 10%, and 20% PbO from room temperature up to 600\u0026deg;C. As shown in the TGA and DTGA analyses, the total weight loss reduced, and thermal stability improved in the lead-containing composites. However, a descending trend in the glass transition temperature was seen in the samples containing fillers, which was probably related to aggregates deformation.\u003c/p\u003e \u003cp\u003eOverall, the studied composites showed an acceptable radioprotective efficiency against low- and medium-energy radiations, and a good agreement was observed between the experimental and computational data for lead-containing composites up to weight percentages of 20%. However, the formation of lumps and heterogeneity in the filler distribution of the composite could markedly affect the radiation protection efficiency. It was found that a higher heterogeneity would result in the greater deviation of the measured attenuation coefficient from the calculated value. Here, at the highest filler weight percentage (50%), this heterogeneity reduced the consistency between the experimental and computational data and reduced the radiation attenuation efficiency. Since PA6/PbO-based radioprotectant composites are novel materials, it is strongly recommended to further investigate their characteristics in future experiments while considering the limitations of this study.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflict of Interest\u003ch2\u003e \u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThis study was extracted as part of a Master's thesis by Mr. H. Shooli, MSc student at Islamic Azad university of Arsanjan. We appreciate those who supported us in conducting this study, especially the personnel and management support and cooperation of the staff at the Nuclear Science and Technology Research Institute of Iran which resulted in the success of this research project. Furthermore, we would like to offer special thanks for the sincere spiritual support and encouragement provided by the Vice-Chancellor of Research at the Shiraz University of Medical Sciences (SUMS).\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003e\u0026nbsp;[1] Classic K, Le-Guen B, Kase K , Vetter R. Safety and radiation protection culture. In\u0026nbsp;Radiological Safety and Quality. 2014; pp. 263-277. Springer, Dordrecht.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;[2] Holmberg O, Czarwinski R, Mettler F. The importance and unique aspects of radiation protection in medicine.\u0026nbsp;European journal of radiology. 2010;\u0026nbsp;76(1): 6-10.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;[3] Zakariya N, Kahn, MTE. 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Radiation Physics and Chemistry. 2018; 145:160-73.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Polymeric composites, Polyamide 6, Lead monoxide, Radiation shields.","lastPublishedDoi":"10.21203/rs.3.rs-1176766/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1176766/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study aimed to introduce new composites, containing polyamide-6 (PA6) and lead monoxide (PbO), to protect against ionizing photon sources used for diagnostic and therapeutic purposes. Five composites, containing various weight percentages of PbO filler (0, 5, 10, 20, and 50%), were developed in this study. Initially, the numerical attenuation value was estimated using XMuDat program by calculating the mass attenuation coefficients at different energy levels. Next, the samples were synthesized based on the melt-mixing method in a laboratory mixing extruder, and their characteristics were determined by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Finally, experimental radiation attenuation tests were carried out. Based on the SEM results, the acceptable filler weight percentage was up to 20%; however, substantial aggregates formation was observed at the highest weight percentage. The results of XRD analysis showed a higher tendency for crystallization by decreasing the amorphous area, while increasing the filler weight percentage. Moreover, the amount of mass loss was monitored at different temperatures, revealing that the filler incorporation improved the thermal durability of the samples. According to the radiation results, a good agreement was observed between the experimental and computational data, except when aggregates formation was substantial. According to the experimental data, by increasing the lead weight percentage from 0% (crude PA6) to 50%, the half-value layer decreased from 3.13 to 0.17 cm at an energy level of 59 keV and from 7.28 to 4.97 cm at an energy level of 662 keV. Considering these promising results, the applicability of PA6/PbO composites for protection against low- and medium-energy ionizing photon sources must be investigated in future studies.\u003c/p\u003e","manuscriptTitle":"Assessment of New Composites Containing Polyamide-6 and Lead Monoxide as Shields against Ionizing Photonic Radiation based on Computational and Experimental Methods","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2021-12-28 17:42:04","doi":"10.21203/rs.3.rs-1176766/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision","date":"2022-04-18T04:37:20+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2022-04-11T03:00:49+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2022-03-15T14:47:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"63e931d2-79de-4aab-83fc-7a39c727f6b9","date":"2022-03-10T12:18:27+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2022-03-09T13:28:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2022-03-09T13:21:49+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2021-12-22T13:56:59+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2021-12-22T09:17:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2021-12-16T08:46:49+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"190a9300-23b5-46ec-960d-6b630d336b1a","owner":[],"postedDate":"December 28th, 2021","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2022-05-18T03:14:11+00:00","versionOfRecord":[],"versionCreatedAt":"2021-12-28 17:42:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1176766","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1176766","identity":"rs-1176766","version":["v1"]},"buildId":"FbvkV6FR0MCFSLy54lSbu","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}