RESUMO
Antifouling coatings containing biocidal agents can be used to prevent the accumulation of biotic deposits on submerged surfaces; however, several commercial biocides can negatively affect the ecosystem. In this study, various formulations of a potential biocide product comprising copper nanoparticles and capsaicin supported on zeolite ZSM-5 were analyzed to determine the influence of the concentration of each component. The incorporation of copper was evidenced by scanning electron microscopy and energy dispersive spectroscopy. Similarly, Fourier-transform infrared spectroscopy confirmed that capsaicin was supported on the zeolite surface. The presence of capsaicin on the external zeolite surface significantly reduced the surface area of the zeolite. Finally, bacterial growth inhibition analysis showed that copper nanoparticles inhibited the growth of strains Idiomarina loihiensis UCO25, Pseudoalteromonas sp. UCO92, and Halomonas boliviensis UCO24 while the organic component acted as a reinforcing biocide.
RESUMO
The global demand for products manufactured with carbon fibers (CFs) has increased in recent years; however, the waste generated at the end of the product lifetime has also increased. In this research, the impact of the addition of carbon nanotubes (CNTs) on the interlaminated resistance of recycled carbon fibers (RCFs) was studied. In this work, a recycling process of the composite material was applied via thermolysis to obtain the CFs, followed by the growth of CNTs on their surface using the Poptube technique. The recycling temperature were 500 °C and 700 °C; and ferrocene and polypyrrole were used to grow CNTs on CFs surface. CNTs were verified by Raman spectroscopy and scanning electron microscopy (SEM). Finally, to determine the interlaminar resistance, a double cantilever beam (DCB) test was performed. The results indicate that with Poptube technique, CNTs can be grown on RCFs using both impregnations. Thermolysis recycling process at 500 °C allowed CFs without resin residues and without visible damage. The DCB tests showed a decrease in the fracture resistance in mode I loading of 34.9% for the polypyrrole samples and 29.3% for the ferrocene samples compared with the virgin carbon fibers (VCFs) samples with a resistance of 1052.5 J/m2.
RESUMO
Nanocomposites and a composite based on poly(butylene adipate-co-terephthalate) (PBAT) were synthesized using commercial copper nanoparticles (Cu-NPs), copper/cuprous oxide nanoparticles (Cu|Cu2O-NPs), and copper sulfate (CuSO4), respectively. The Cu|Cu2O-NPs were synthesized using chemical reduction and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The synthesis of Cu|Cu2O-NPs yielded a mixture of Cu and Cu2O, with metal Cu having a spherical morphology of approximately 40 nm in diameter and Cu2O with a diameter of 150 nm. To prepare the nanocomposites (NCs) and the composite material (MC), the NPs and the CuSO4 salt were incorporated into the PBAT matrix in concentrations of 1, 3, and 5% p/p via an ex situ method. Fourier transform infrared spectroscopy (FTIR), a tensile test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and agar diffusion assays were used for structural, thermomechanical, and antimicrobial characterization. Results showed that the reinforcements did not modify the chemical structure of the PBAT and only slightly increased the percentage of crystallization. The mechanical and thermal properties of the PBAT did not change much with the addition of fillers, except for a slight increase in tensile strength and thermal stability, respectively. The agar diffusion antimicrobial assays showed that the NCs and MCs had good inhibitory responses against the nonresistant strains Enterococcus faecalis, Streptococcus mutans, and Staphylococcus aureus. The MCs based on CuSO4 had the highest biocidal effect, even against the resistant bacteria Acinetobacter baumannii.