Thomaz Jacintho Lopes

This study investigates the ballistic performance and energy dissipation mechanisms of epoxy composites reinforced with raffia fabric at fiber volume fractions of 10%, 20%, and 30% under 9 mm full metal jacket projectile impact. Ballistics tests were conducted to determine impact and residual velocities, absorbed energy, absorption efficiency, equivalent ballistic limit, and momentum reduction. All tests were performed at similar impact velocities (≈433 m/s), corresponding to an incident energy of approximately 750 J. The results revealed a clear inverse relationship between raffia content and energy absorption capability. The ER10 composite exhibited the highest performance, with an absorbed energy of 176.7 ± 9.7 J, absorption efficiency of 23.5 ± 0.9%, and momentum reduction of 0.1253 ± 0.0053. Increasing the fiber fraction to 20% (ER20) and 30% (ER30) led to progressive reductions in absorbed energy to 119.7 ± 2.7 J and 77.7 ± 9.0 J, with efficiencies of 15.95 ± 0.26% and 10.30 ± 1.12%, respectively. The residual velocity increased from 379.3 ± 2.5 m/s (ER10) to 397.0 ± 2.1 m/s (ER20) and 411.1 ± 1.6 m/s (ER30). One-way ANOVA detected statistically significant differences in absorbed energy and absorption efficiency among the different fiber volume fractions (p < 0.001). The results demonstrate a trade-off between stiffness and toughness and indicate that raffia-reinforced composites can play complementary roles in sustainable multilayered armor systems.

Conductive composites are a flexible class of engineered materials that combine conductive fillers with an insulating matrix—usually made of ceramic, polymeric, or a hybrid material—to customize a system’s electrical performance. By providing tunable electrical properties in addition to benefits like low density, mechanical flexibility, and processability, these materials are intended to fill the gap between conventional insulators and conductors. The increasing need for advanced technologies, such as energy storage devices, sensors, flexible electronics, and biomedical interfaces, has significantly accelerated their development. The electrical characteristics of composite materials, including metallic, ceramic, polymeric, and nanostructured systems, are thoroughly examined in this review. The impact of various reinforcement phases—such as ceramic fillers, carbon-based nanomaterials, and metallic nanoparticles—on the electrical conductivity and dielectric behavior of composites is highlighted. In addition to conduction models like correlated barrier hopping and Debye relaxation, the study investigates mechanisms like percolation thresholds, interfacial polarization, and electron/hole mobility. Because of the creation of conductive pathways and improved charge transport, developments in nanocomposite engineering, especially with regard to graphene derivatives and silver nanoparticles, have shown notable improvements in electrical performance. This work covers the theoretical underpinnings and physical principles of conductivity and permittivity in composites, as well as experimental approaches, characterization methods (such as SEM, AFM, and impedance spectroscopy), and real-world applications in fields like biomedical devices, sensors, energy storage, and electronics. This review provides important insights for researchers who want to create and modify multifunctional composite materials with improved electrical properties by bridging basic theory with technological applications.

This article explores the foundational principles of ionizing radiation and provides a comprehensive overview of its impact on thermoplastic polymers. Ionizing radiation, encompassing gamma rays, X-rays, and electron beams, has been extensively studied due to its capacity to alter the molecular structure of polymers. These changes enable advancements in various applications by promoting molecular crosslinking, controlled degradation, molecular grafting, and crystallinity adjustments. The article delves into the fundamental mechanisms of radiation thermoplastic polymer interactions, including ionization, electronic excitation, and free radical formation. It highlights how these processes lead to structural transformations that enhance the physical, thermal, and mechanical properties of thermoplastic polymers. Factors such as radiation type, absorbed doses, temperature, and environmental conditions are discussed in the context of their role in controlling these modifications. Key practical applications are identified across fields such as medicine, food packaging, aerospace, and industry. Examples include the production of sterilizable medical devices, enhanced food packaging for longer shelf life, and radiation-resistant materials for the aerospace and nuclear sectors. Despite its many advantages, the article also emphasizes challenges such as process variability, polymer sensitivity to radiation, and standardization difficulties. The review underscores emerging research directions, including optimizing irradiation parameters and integrating advanced characterization techniques like Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray diffraction (XRD). The development of new polymer blends and composites, designed for irradiation-induced property enhancement, represents a promising area of innovation.

This review addresses the application of silicon-germanium (SiGe) semiconductors as electronic components, highlighting their enhanced electronic and physical properties compared to pure silicon semiconductors. SiGe Semiconductors are widely used in high-performance devices, such as heterojunction bipolar transistors (HBTs) and radio-frequency integrated circuits (RFICs), due to their ability to improve speed, efficiency, and overall device performance. Incoporating Ge into Si increases electron mobility, enabling devices to operate at higher speeds and with lower power consumption, which is crucial for portable and low-power applications. Additionally, SiGe semiconductors are compatible with existing Si semiconductor manufacturing processes, facilitating their integration into complementary metal-oxide semiconductor (CMOS) technologies. Another significant benefit is their improved high-frequency performance, making them suitable for applications such as wireless communications and radar technologies. By varying the Ge composition in SiGe, it is possible to adjust the bandgap and lattice strain, providing flexibility in the design of electronic and optoelectronic devices. These attributes make SiGe semiconductors an ideal choice for a wide range of advanced applications where performance and energy efficiency are essential.

The research examined the transmission factor for thermal neutrons utilizing the Watt spectrum for uranium-235 fission with MCNP5 simulations. Throughout the analysis, it was found that borated polyethylene performed worse than regular polyethylene. This disparity implies that, while borated polyethylene possesses advantageous moderating properties, it might introduce features that decrease its efficiency in thermal neutron transmission. These findings underscore the importance of evaluating not only the moderating capabilities of materials but also other attributes that can affect the behavior of thermal neutrons.

In this study, the importance of simulations conducted in MCNP5 and the modifications implemented in 316 steel to optimize energy efficiency in nuclear power production are explored. Graphene are investigated as promising additives due to their low absorption cross-section for thermal neutrons, which facilitates a more significant participation of neutrons in fission and heat generation. Through the use of the MCNP5 code, simulations were conducted to analyze a hypothetical UO2 fuel element with different enrichment zones to evaluate its performance. The results highlight that the inclusion of graphene in the fuel cladding alloy has a significant impact on neutron production, suggesting that this addition may compromise energy generation efficiency. In summary, this study emphasizes the potential of graphene s as additives to enhance nuclear fuel performance, promoting safer, more efficient, and sustainable nuclear energy.

In this study, the importance of simulations conducted in MCNP5 and the modifications implemented in 316 steel to optimize energy efficiency in nuclear power production are explored. Molybdenum (Mo) is investigated as a promising additive due to its low absorption cross-section for thermal neutrons, which facilitates a more significant participation of neutrons in fission and heat generation. Through the use of the MCNP5 code, simulations were conducted to analyze a hypothetical UO2 fuel element with different enrichment zones to assess its performance. The results highlight that the inclusion of molybdenum in the fuel cladding alloy has a significant impact on neutron production, suggesting that this addition may compromise energy generation efficiency. In summary, this study emphasizes the potential of molybdenum as an additive to enhance nuclear fuel performance, promoting safer, more efficient, and sustainable nuclear energy.