RESUMO
The design of shielding materials against ionizing radiation while simultaneously displaying enhanced multifunctional characteristics remains challenging. Here, for the first time, we present moldable paraffin-based iron nano- and microcomposites attenuating γ- and X-radiation. The moldability was gained by the warmth-of-hands-driven plasticity, which allowed for obtaining a specific shape of the composites at room temperature. The manufactured composites contained iron particles of various sizes, ranging from 22 nm to 63 µm. The target materials were widely characterized using XRD, NMR, Raman, TGA, SEM, and EDX. In the case of microcomposites, the shielding properties were developed at two concentrations: 10 and 50 wt %. The statistically significant results indicate that the iron particle size has a negligible effect on the shielding properties of the nano- and microcomposites. On the other hand, the higher iron particle contents significantly affected the attenuating ability, which emerged even as superior to the elemental aluminum in the X-ray range: at a 70 kV anode voltage, the half value layer was 6.689, 1.882, and 0.462 cm for aluminum, paraffin + 10 wt % Fe 3.5-6.5 µm, and paraffin + 50 wt % Fe 3.5-6.5 µm microcomposites, respectively. Importantly, the elaborated methodology-in situ cross-verified in the hospital studies recording real-life sampling-opens the pathway to high-performance, eco-friendly, lightweight, and recyclable shields manufactured via fully reproducible and scalable protocols.
RESUMO
Two types of graphite/diamond (GD) particles with different ash content was applied to prepare new electroconductive polylactide (PLA)-based nanocomposites. Four samples of nanocomposites for each type of GD particles with mass fraction 0.01, 0.05, 0.10, and 0.15 were prepared via an easily scalable method-melt blending. The samples were subjected to the studies of electrical properties via broadband dielectric spectroscopy. The results indicated up to eight orders of magnitude improvement in the electrical conductivity and electrical permittivity of the most loaded nanocomposites, in reference to the neat PLA. Additionally, the influence of ash content on the electrical conductivity of the nanocomposites revealed that technologically less-demanding fillers, i.e., of higher ash content, were the most beneficial in the light of nanofiller dispersibility and the final properties.
RESUMO
This paper presents a study on the electrical properties of new polylactide-basednanocomposites with the addition of silicon-dioxide-lignin nanoparticles and glycerine as a plasticizer.Four samples were prepared with nanoparticle mass fractions ranging between 0.01 to 0.15(0.01, 0.05, 0.10, and 0.15), and three samples were prepared without nanoparticle filler-unfilledand unprocessed polylactide, unfilled and processed polylactide, and polylactide with Fusabondand glycerine. All samples were manufactured using the melt mixing extrusion techniqueand injection molding. Only the unfilled and unprocessed PLA sample was directly preparedby injection molding. Dielectric properties were studied with broadband spectroscopy in a frequencyrange from 0.1 Hz to 1 MHz in 55 steps designed on a logarithmic scale and a temperature rangefrom 293.15 to 333.15 K with a 5 K step. Optical properties of nanocomposites were measuredwith UV-VIS spectroscopy at wavelengths from 190 to 1100 nm. The experimental data show thatthe addition of silicon-dioxide-lignin and glycerine significantly affected the electrical propertiesof the studied nanocomposites based on polylactide. Permittivity and electrical conductivity showa significant increase with an increasing concentration of nanoparticle filler. The optical properties arealso affected by nanofiller and cause an increase in absorbance as the number of silicon-dioxide-ligninnanoparticles increase.