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This study investigated the application of supercritical carbon dioxide (CO2) for the extraction of essential oils from plant materials with anxiolytic potential, focusing on the leaves of burrito (Aloysia polystachya) and the seeds of sucupira-preta (Bowdichia virgilioides). The supercritical extraction technique was chosen for its ability to produce high-purity extracts without residual solvents and to reduce the environmental impact. This study evaluated the influence of temperature (40 °C, 50 °C, and 60 °C) and pressure (22 MPa, 25 MPa, and 28 MPa) on extraction efficiency using a 22 factorial design with triplicates at the central point. The maximum yields were 1.2% for burrito leaves and 4.2% for sucupira-preta seeds. Despite their relatively low yields, the extracts contained a diverse range of chemical compounds, including fatty acids (oleic, linoleic, and palmitic acids), squalene, β-carotene, vitamin E, and other bioactive molecules with antioxidant, anti-inflammatory, and immunomodulatory properties. Statistical analysis demonstrated that pressure was the most influential factor affecting yield, whereas temperature played a secondary role. The Sovová kinetic model provided a good fit for the extraction curves, with determination coefficients (R2) above 0.95, thus validating the efficiency of the method. These results highlight the pharmaceutical potential of these extracts, particularly for therapeutic and anxiolytic purposes. [ABSTRACT FROM AUTHOR]

Given the growing interest of the rubber industry in seeking alternatives that contribute to environmental sustainability, this work aims to present a study of the mechanical, thermal, and structural properties of natural rubber composites using tannin extracted from Acacia mearnsii as an antioxidant agent. Tannin is a natural and biodegradable product, rich in polyphenols and known for its antioxidant properties. The analyses assessed the effectiveness of incorporating tannins (0, 1, 1.5, and 2 parts per hundred rubber) into sulfur-crosslinked natural rubber composites using a binary accelerator system across three distinct vulcanization schemes: conventional, semi-efficient, and efficient. Initially, tannin characterization tests were conducted, revealing characteristic polyphenol bands of proanthocyanidin catechins, a high total phenolic content, and a substantial reduction in antioxidant activity. These findings highlight the significant antioxidant potential of tannins, particularly for industrial and biological applications. The analyses of the characteristics of natural rubber composites with tannin incorporation indicated that the type of vulcanization process directly affects the antioxidant action of the plant tannin, with the tannins being most effective in the efficient system due to the formation of monosulfidic and disulfidic bonds. Furthermore, the incorporation of tannin did not compromise the physical and chemical properties of the materials, highlighting it as a viable additive for the rubber industry. [ABSTRACT FROM AUTHOR]

The growing demand for more sustainable routes and processes in the mixture separation and purification industry has generated a need to search for innovations, with new solvent alternatives being a possible solution. In this context, a new class of green solvents, known as deep eutectic solvents (DESs), has been gaining prominence in recent years in both academic and industrial spheres. These solvents, when compared to ionic liquids (ILs), are more environmentally friendly, less toxic, low-cost, and easier to synthesize. In addition, they have significantly lower melting points than their precursors, offering a promising option for various applications in this industrial sector. Understanding and studying the thermodynamic behavior of systems composed of these substances in purification and separation processes, such as liquid–liquid extraction and azeotropic distillation, is extremely important. This work aimed to study the phase behavior of liquid–liquid equilibrium (LLE) and vapor–liquid equilibrium (VLE) of water + 1-butanol + DES (choline chloride + glycerol) systems with a molar ratio of 1:2. Experimental LLE data, obtained at 298.15 K and 101.3 kPa, and VLE data, obtained at 101.3 kPa and in the temperature range of 364.05 K–373.85 K, were submitted to the thermodynamic quality/consistency test, proposed by Marcilla et al. and Wisniak, and subsequently modeled using the gamma–gamma approach for the LLE and gamma–phi for the VLE. The non-random two-liquid (NRTL) model was used to calculate the activity coefficient. The results are presented for the VLE in a temperature–composition phase diagram (triangular prism) and triangular phase diagrams showing the binodal curve and tie lines (LLE). The separation and distribution coefficients of LLE were determined to evaluate the extractive potential of the DES. For the VLE, the values of the relative volatility of the system were calculated, considering the entrainer free-basis, to evaluate the presence or absence of azeotropes in the range of collected points. From these data, it was possible to compare DES with ILs as extracting agents, using data from previous studies carried out by the research group. Therefore, the results indicate that the NRTL model is efficient at correlating the fluid behavior of both equilibria. Thus, this study serves as a basis for future studies related to the understanding and design of separation processes. [ABSTRACT FROM AUTHOR]

Given the increasing need for sustainable solutions and the large amount of improperly discarded end‐of‐life tires, recovered carbon black (rCB) from tire pyrolysis was investigated as a filler for rubber composites. This study considered rCB as an alternative to commercial carbon black due to its sustainability and CO2 emissions reduction. Composites with varying rCB contents (0 to 50 per 100 rubber) were produced and assessed for mechanical properties, such as hardness, abrasion resistance, and rheometric tests. The findings were used to train artificial neural networks (ANNs) with MATLAB software to predict rCB contents. Input parameters included optimal curing time, minimum and maximum torque, and results of mechanical tests like Shore A hardness and abrasion loss. The model was trained on data from 90 samples, with 10 reserved for validation. The predicted outcomes closely matched the experimental data, with a maximum prediction error of less than 3%. This indicates that ANNs are effective tools for intelligently modeling the curing process of natural rubber mixtures, minimizing material waste, optimizing production time, and determining suitable carbon black contents for desired mechanical properties. [ABSTRACT FROM AUTHOR]

Ethylene propylene diene monomer (EPDM) is a synthetic rubber widely used in industry and commerce due to its high thermal and chemical resistance. Nanotechnology has enabled the incorporation of nanomaterials into polymeric matrixes that maintain their flexibility and conformation, allowing them to achieve properties previously unattainable, such as improved tensile and chemical resistance. In this work, we summarize the influence of different nanostructures on the mechanical, thermal, and electrical properties of EPDM-based materials to keep up with current research and support future research into synthetic rubber nanocomposites. [ABSTRACT FROM AUTHOR]

The refrigeration industry produces millions of tons of waste polyurethane (PU) every year, which can cause environmental damage and human health problems. This article analyzes the use of waste PU as filler in composites made of styrene butadiene rubber (SBR) and natural rubber (NR) to produce shoe soles. The interfacial interaction of said filler was evaluated by the Flory–Rehner method (swelling) using the equation developed by Lorenz–Park. The results of this evaluation were later compared with those obtained by the Mooney–Rivlin method using the data from stress–strain tests. According to the results of the tensile strength tests, the composites filled with waste PU present stress–strain curves that are like those of metallic materials that have low elastic strength but high plastic strength. Using the Lorenz–Park equation, the filled composites examined in this study exhibited values above 0.7, which means a strong filler–rubber interaction. Scanning Electron Microscopy and Fourier‐Transform Infrared Spectroscopy were used to investigate the morphology of the composites in detail. [ABSTRACT FROM AUTHOR]

This study provides experimental insights into the liquid–liquid equilibrium (LLE) of a system consisting of fatty acid ethyl ester (FAEE) derived from licuri oil, glycerol, and ethanol, evaluated at various temperatures and standard atmospheric pressures. FAEE was synthesized through transesterification of licuri oil using NaOH as a catalyst. The liquid phase compositions were assessed via titration, and the results were consistent with the solubility curves and overall compositions. Data reliability was confirmed using Hand and Othmer-Tobias correlations, with a determination coefficient (R2) of 1, validating the dependability of the results. The NRTL model was employed to correlate the LLE data, yielding a root-mean-square deviation (RMSD) of approximately 1.20%, signifying a strong correlation with experimental uncertainties. The selectivity (S) and distribution (D) parameters indicated the efficacy of glycerol in the system, with S values exceeding 1 under all conditions tested. This investigation is crucial for biodiesel production, highlighting the potential of licuri oil as a renewable feedstock and the importance of phase equilibrium studies in the separation processes of biodiesel production products. [ABSTRACT FROM AUTHOR]

In this work investigated the possibility of applying a superficial treatment to ultra-fine calcium carbonate aiming to improve its interaction with the polymer chains of natural rubber so it does not act just as a filler. Commercial processes commonly use 40 phr of Silica as reinforcement filler. Here, we have evaluated the partial replacement of Silica by two types of calcium carbonate into hybrid natural rubber composites, untreated ultra-fine calcium carbonate and with ultra-fine calcium carbonate treated with 2% Chartwell C-515.71HR®. We added calcium carbonate fillers to the composite mixtures (as replacements for commercial silica treated with silane) and studied their influence on the vulcanization process. According to our findings, between 25% and 75% of the silica can be replaced with treated calcium carbonate, and up to 30 parts of CaCO3 can be combined with 100 parts of NR without compromising the properties of the polymer matrix (NR), which generates economic advantages for this industry. Treated calcium carbonate was able to link the inorganic and organic parts of the composite due to its bifunctionality; hence, it can be used as a filler to partially replace silica in hybrid NR composites. [ABSTRACT FROM AUTHOR]

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