“…It found its application in textiles, belts, coated fabrics, insulations, cables, bands, tires and many more [ 66 , 67 , 68 , 69 , 70 ]. To improve the technical and exploitation properties of NR-based vulcanizates such as tensile strength, barrier properties or thermal conductivities, natural or synthetic fillers and additives are often used [ 55 , 71 , 72 , 73 ]. Following the general trend to reduce the usage of synthetic components in polymer technology by replacing them with renewable raw materials, the authors of the manuscript aimed to investigate the influence of antioxidant freeze-dried natural extracts on the elastomer mixture’s resistance to simulated aging processes.…”
The research article aimed to examine the antioxidant nature of freeze–dried extracts from Urtica dioica L. and Mentha piperita L. and to present a deep characterization of their influence on the properties of natural rubber–based vulcanizates before and after simulated aging processes. Natural extracts were prepared in three solvent systems at selected volume ratios: water (100), methanol–water (50/50), ethanol–water (50/50), which were further lyophilized and used as additive to natural rubber mixtures. Freeze–dried materials were investigated by UV–VIS diffuse reflectance spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), thermal stability by thermogravimetric analysis (TGA). Antioxidant activity and total phenolic content (TPC) were also examined. Prepared samples were subjected to accelerated simulated degradation processes by using ultraviolet and thermo-oxidative aging. Vulcanizates resistance to degradation effects was determined by the study of cross-linking density (equilibrium swelling method), mechanical properties (tensile strength, elongation at break) and color change in comparison with the results of the reference samples. The research showed that analyzed extracts are characterized by a high content of polyphenols and antioxidant activity, thus have a protective influence on elastomer vulcanizates against damaging effects of aging processes, which consequently extends the lifetime of materials.
“…It found its application in textiles, belts, coated fabrics, insulations, cables, bands, tires and many more [ 66 , 67 , 68 , 69 , 70 ]. To improve the technical and exploitation properties of NR-based vulcanizates such as tensile strength, barrier properties or thermal conductivities, natural or synthetic fillers and additives are often used [ 55 , 71 , 72 , 73 ]. Following the general trend to reduce the usage of synthetic components in polymer technology by replacing them with renewable raw materials, the authors of the manuscript aimed to investigate the influence of antioxidant freeze-dried natural extracts on the elastomer mixture’s resistance to simulated aging processes.…”
The research article aimed to examine the antioxidant nature of freeze–dried extracts from Urtica dioica L. and Mentha piperita L. and to present a deep characterization of their influence on the properties of natural rubber–based vulcanizates before and after simulated aging processes. Natural extracts were prepared in three solvent systems at selected volume ratios: water (100), methanol–water (50/50), ethanol–water (50/50), which were further lyophilized and used as additive to natural rubber mixtures. Freeze–dried materials were investigated by UV–VIS diffuse reflectance spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), thermal stability by thermogravimetric analysis (TGA). Antioxidant activity and total phenolic content (TPC) were also examined. Prepared samples were subjected to accelerated simulated degradation processes by using ultraviolet and thermo-oxidative aging. Vulcanizates resistance to degradation effects was determined by the study of cross-linking density (equilibrium swelling method), mechanical properties (tensile strength, elongation at break) and color change in comparison with the results of the reference samples. The research showed that analyzed extracts are characterized by a high content of polyphenols and antioxidant activity, thus have a protective influence on elastomer vulcanizates against damaging effects of aging processes, which consequently extends the lifetime of materials.
“…Palm oil facilitates the nanocellulose dispersion in the elastomeric compound, generating a balance between hydrophobic and hydrophilic functional groups which leads to a stronger interfacial interaction. 30-32 Figure 5.Chemical reaction between SBR, (a) palm oil and (b) nanocellulose.…”
Silica and carbon black (CB) are the most used reinforcement fillers in elastomeric compositions; however, their obtention and usage might result in environmental and human health damages. The same happens to the plasticizers used in elastomeric compounds, which contain a high content of polycyclic aromatics. To use reinforcement and plasticizer loads from natural sources, the performance of an elastomeric compound by partially replacing CB with nanofibrillated cellulose (CEL) provided with Eucalyptus spp. shavings was evaluated in this work, as well as, the use of palm oil to replace aromatic oils. Nanofibrilated cellulose was obtained by grinding in a micronizing mill. As a characterization of the raw material, the thermal, chemical and morphological properties, as well as particle size analysis of the cellulose suspension were evaluated by the particle size analyzer. From the vulcanized material, the physical, mechanical, dynamic-mechanical properties, cross-link density, and swelling index in solvents were evaluated. As the main results obtained, the presence of CEL clusters seen by scanning electron microscopy with nanofibers with diameters of 100–85 nm was observed. The dynamic light scattering particle size analyzers (DLS) showed nanoparticles from 1 to 100 nm. The rheometric properties showed lower values for the parameters of safety time, optimal vulcanization time, and maximum and minimum torques when compared to samples with CEL as CB. For tear resistance properties, samples with the presence of nanofibrilated cellulose showed 48% more resistance than samples with CB, in the modulus of elasticity, cross-link density, and swelling index, a better performance was also achieved for the samples with CEL, along with presenting a similar behavior in the hardness property between samples with the presence of nanofibrillates and those with CB. Palm oil, a substitute for aromatic oil, was found to be similar in the evaluated properties results, with interaction with CEL, by chemical affinity, which can replace aromatic oil.
“…This characteristic is needed in photocatalysis because the OH group can react with holes and prevent the recombination of electronhole pairs. The 2,015.9 absorption band in the FTIR spectrum of the CTAB samples can be attributed to the CH bond vibrations of the methyl and methylene groups, respectively, of the surfactant residues [20]- [22].…”
TiO2 preparation has been carried out with the addition of cetyl trimethyl ammonium bromide (CTAB) surfactant. The sol-gel method is used in the preparation of TiO2, where TiCl4 is used as a precursor. The resulting TiO2 was characterized using XRD, FTIR, XRF and SEM. XRD results show the crystal size of TiO2 17.75 nm with the rutile phase. The FTIR results show a broad absorption band between 800 and 400 cm−1 by Ti–O vibrations in the crystal lattice. The XRF results showed that the TiO2 content was 80.80%. Morphological results showed an irregular ball-like structure that was less aggregated. The characterization results show that TiO2 can be used as a coating on fabrics with antibacterial properties.
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