This study aims to investigate changes in the structural properties of alkali/acid‐ultrasound modified Agave fibers and their performance immersed on a polyvinyl alcohol (PVA) matrix with plasticizer during melt mixing processing. Structural analysis revealed that ultrasound enhances the effectiveness of the conventional alkaline/acid treatments to modify fibers since the simultaneous treatment increased the partial removal of lignocellulosic components, water molecules, and amorphous regions which improved their processability on a PVA matrix. Specific energy consumption values indicated that during melt mixing the modified fibers required more energy to expose the chains of cellulose fraction to function as an interaction site for PVA chains. Once the mixture was homogenized, the fiber‐matrix interactions promoted high viscosity, friction, and mechanical stress in the chamber. Therefore, the modified fibers restricted the interaction between plasticizer and PVA in the obtained films, resulting in a highly structured, and reinforced network, increasing the storage modulus as dynamic mechanical analysis indicated. These findings highlight a feasible way to valorize Agave fibers and allow the understanding of the matrix‐fiber interactions during melt mixing processing, useful to predict the structural and mechanical properties of the films.

Green synthesis may be a useful approach to achieve selective cytotoxicity of silver nanoparticles on cancer cells and healthy cells. In this study, the concomitant biosynthesis of silver (Ag)/silver chloride (AgCl) nanoparticles from pineapple peel extracts and their behavior on the breast cancer cell line MCF-7 is shown. Bioreactions were monitored at different temperatures. Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques were used to characterize nanoparticle development. The breast cancer cell line MCF-7 was used as a test model to study the cytotoxic behavior of Ag/AgCl nanoparticles and, as a counterpart, the nanoparticles were also tested on mononuclear cells. Ag/AgCl nanoparticles with spherical and triangular morphology were obtained. The size of the nanoparticles (10–70 nm) and the size distribution depended on the reaction temperature. A dose close to 20 µg/mL of Ag/AgCl nanoparticles considerably decreased the cell viability of the MCF-7 line. The best cytotoxicity effects on cancer cells were obtained with nanoparticles at 60 and 80 °C where cell viability was reduced up to 80% at a concentration of 50 µg/mL. A significant preference was observed in the cytotoxic effect of Ag/AgCl nanoparticles against cancer cells in comparison to monocytes.

This study aims to investigate the effect of ground tire rubber (GTR) treated by acetone on mechanical and morphological properties of ethylene-vinyl acetate (EVA) matrix. Polymeric EVA/GTR (0, 10, 20, 30, and 40 phr) compounds were achieved through extrusion and batch foaming process. TGA and NMR analysis revealed that oils and additives were removed from the GTR after the acetone treatment. Morphological characterization showed cell sizes below 100 μm in the compounds with treated GTR, which improved the mechanical performance of EVA/GTR compounds. The results indicated that the acetonetreated GTR are a suitable raw material to obtain foam compounds useful in vibrations absorber and isolation applications.

The combination of keratin fibers (KF), obtained from poultry feathers, with chitosan (Ch) are employed in polypropylene (PP) composites to enhance the flame-retardant (FR) properties. The combined effect of each additive and the use of functionalized PP with ammonium polyphosphate (PP-gAPP) as a compatibilizer, compared with PP-gMA, on composite FR properties was analyzed. This compatibilizer was prepared by melt reaction of maleic anhydride grafted PP (PP-gMA) with ammonium polyphosphate (APP). The grafting of APP was characterized by FTIR, XRD, and NMR. PP/KF/Ch composites using PP-gAPP as compatibilizer were characterized by TGA, mechanical properties, and fire-retardant tests such as UL-94 (HB), limiting oxygen index (LOI), and cone calorimeter evaluations. These tests demonstrated the enhancement in fire-retardant characteristics obtained by using PP-gAPP as a compatibilizer agent compared with PP-gMA. The combination of the additives (KF and Ch) with PP-gAPP as compatibilizer in PP, increases the modulus and tensile strength and significantly improves the LOI and reduces the peak heat release rate during cone calorimetry tests with better thermal stability and a noticeable reduction in horizontal burning rate. Most important, the results indicated that the combination of these additives produce similar flame retardancy than a reference sample with high magnesium hydroxide loading. These composites are a promising way to meet the growing demand for high-performance materials with FR characteristics using bio-fire retardant additives such as KF and Ch, in sustainable and environmentally friendly composites.

No abstract