Resumen en Inglés:

Abstract This study demonstrates the sustainable production and physicochemical characterization of nanofibers from bacterial cellulose (BC) waste generated during the commercial production of wound dressing films, using TEMPO-mediated oxidation. The produced BC nanofibers (TO-BCNF) were evaluated in terms of yield (82.68%) and water content (98.84%), and characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). TEM revealed nanofibers with an average diameter of 116.07 ± 21.35 nm, while XRD confirmed the preservation of the semi-crystalline structure of BC, with a crystallinity index of 88.15%. TGA indicated thermal stability with degradation onset at 186 °C. The process also preserved the nanofibrillar morphology and the three-dimensional network of BC. This sustainable approach supports the circular bioeconomy by converting industrial waste into functional nanomaterials, offering potential for applications in wound dressings, films, hydrogels, and controlled release systems.

Resumen en Inglés:

Abstract Hot melt adhesives based on blends of poly (ethylene-co-vinyl acetate), (EVA), and thermoplastic starch modified with citric acid (TPS), compatibilized with polyolefin grafted with maleic anhydride (PO-g-MA) were prepared. The materials were characterized by scanning electron microscopy (SEM) of fragile fractured surface, rotational viscosimeter (Brookfield) and FTIR. SEM showed interfacial failure in non-compatibilized blends and a decrease in the size of TPS dispersed phase as compatibilizer is added. When adding 5 and 7% of the compatibilizer, results from the viscosimeter indicated increase of 85% and 109% in viscosity, respectively. FTIR showed a dislocation in the absorption of hydrogen bands and ester linkages. These results indicated the effectiveness of the polyolefin functionalized. In performance analysis, compatibilized blends with 25% TPS, exhibited greater adhesion compared to standard hot melt adhesive at low application temperature (140°C), which demonstrates great potential for natural materials in adhesive’s industry.

Resumen en Inglés:

Abstract The accumulation of plastic waste, especially polyethylene terephthalate (PET), is a major environmental concern. This research focuses on the use of recycled polyethylene terephthalate (r-PET) as a building material in concrete, and studies the improvement of its properties by reinforcing it with natural and synthetic fibers. The effect of adding hemp fibers on the mechanical and physical properties of PET composites was investigated. Results after curing each sample for 7, 14, and 28 days showed that reinforcing r-PET with fibers significantly increased compressive strength, flexural strength, and density, making it a suitable option as a complement or partial replacement for conventional concrete. Furthermore, the use of hemp fibers, as a renewable and biodegradable resource, enhances the sustainability of the resulting materials. It contributes to the production of high-performance, environmentally friendly building materials, reduces plastic waste, supports the economy, and can be applied in semi-structural concrete to promote sustainable construction techniques.

Resumen en Inglés:

Abstract Organic pollutants can be broken down by photocatalysis with the help of carbon dots. Also, it is widely used as a material to stop microorganisms from growing. This study synthesized N-doped carbon dots from cocoa fruit skin as a potential antibacterial. TEM images on N-CDs show the material is dispersed well without forming aggregation. The spacing of the lattice fringe formed is around 0.23 nm, corresponding to graphite's diffraction. FTIR spectra show adsorption peak difference between CDs and N-CDs is 1118 cm-1, indicating C-N stretching. UV-Vis absorption spectrum shows the formation of a peak at 294 nm, which shows the π-π* transition of sp2, PL QY of N–CDs in a water solution was about 18.25%. It has been seen that N-CDs work very quickly and kill many bacteria compared to CDs. In both CDs, the highest value for the zone of inhibition is 100 µg mL-1.

Resumen en Inglés:

Abstract In this work, kombucha residue (bacterial cellulose) was obtained after fermentation of six herbal infusions. Culture medium was prepared with 5g/L of plants infusion and sweetened with 50g/L of sucrose. Higher film production was 32,33 g.L-1 after 21 days from culture medium formed by 50% of green tea and 50% of Pereskia aculeate. All pellicles showed antimicrobial activity against S.aureus and SEM of pellicles showed a heterogeneous and dense surface. XDR analysis evidenced cellulose type I properties in pellicles and degree of crystallinity decreased in the pellicles obtained from culture medium with 100% herbal infusions. Thermal properties revealed better thermal stability than kombucha pellicle standard. This research is innovative because it used plants from northeast of Brazil for production of an alternative, low cost and biodegradable material to replace traditional plastics using residues and active agents in addition to reducing pollution.

Resumen en Inglés:

Abstract Polyester (polyethylene terephthalate, PET) and high-modulus polyethylene (HMPE) fibers are currently among the most commonly used materials in the manufacturing of ropes for offshore operations. Several studies have been conducted in analytical, experimental, and numerical domains, addressing various factors such as tensile tests, fatigue, creep, and environmental exposure conditions that influence their mechanical behavior. This work presents data from an experimental study on rupture resistance in semi-finished products (rope yarns) of PET and HMPE fibers subjected to different ultraviolet (UV) radiation exposure durations. The experimental procedure involved UV exposure for up to 84 days, followed by tensile rupture tests based on ISO 2062. The results showed that UV degradation occurs in a monotonic manner for PET, whereas HMPE exhibits relative stability for rope yarns.

Resumen en Inglés:

Abstract Electrospun polycaprolactone (PCL) nanofibers are widely studied for biomedical applications due to their biodegradability and processability, but their limited mechanical strength and bioactivity restrict advanced use. This study addresses these challenges by incorporating four types of functionalized graphene—carboxyl (CFG), hydroxyl (HFG), amine (AFG), and sulfonic (SFG)—into PCL at varying concentrations. Nanocomposite fibers were fabricated via electrospinning and characterized using SEM, FTIR, Raman, DSC, TGA, tensile testing, and MTT assay. Among all, PCL reinforced with 1 wt% SFG showed superior properties, including a tensile strength of 5.8 MPa, 34% thermal residue at 600°C, and 93% cell viability at 72 hours, outperforming pure PCL by over 60% in strength and 9% in biocompatibility. The enhancement is attributed to improved dispersion and strong interfacial bonding from polar functional groups. These results highlight the potential of functionalized graphene to engineer high-performance nanofibers for tissue engineering and regenerative medicine applications.

Resumen en Inglés:

Abstract Limonene, a renewable material derived from citrus fruit peels, can be used as monomer in thiol-ene polymerization with dithiols and tetrathiols to form linear or crosslinked polymers, respectively. The effect of using a thermal- or photoinitiator on polymer properties was evaluated, with the photoinitiator significantly increasing the conversion of the internal unsaturation of limonene with 1,4-butanedithiol (>90%), resulting in higher molecular weights (9,000 g/mol). With pentaerythritiol tetrakis(3-mercaptopropionate), the gel content remained below 15% in thermally initiated reactions (28,000 g/mol) but increased to above 90% in photoinitiated ones. Finally, combining both thiols resulted in an intermediate molecular weight (~13,000 g/mol) for thermal initiation, and a gel content of about 85% for the photoinitiated ones. Thus, thiol-ene reactions stand out as an effective approach for the synthesis of polymers from limonene, with molecular weight and gel content being fine-tuned by the type/ amount of initiator, and by the combination of di- and tetrathiol.

Resumen en Inglés:

Abstract Several numerical simulation strategies for polymer melt flow have been used to optimize simulation time and reduce numerical errors. It is known that in this type of flow, the emergence of numerical diffusion in the cavity walls is common due to the high stresses caused by highly viscous fluids. In order to avoid uniformly refining the entire mesh and increasing simulation time, a common strategy is to use a localized refinement on the cavity walls. In this context, this study presents a standardization in the smoothing of the mesh on the cavity walls for simulations of transient non-isothermal flow of polymer melts. The main results showed that this type of application is highly efficient and contributes to reducing the time and computational effort of simulations of complex cavities with good accuracy.

Resumen en Inglés:

Abstract Boric acid (BA) and nano silica (NS) were used to improve the properties of composite materials based on epoxy resin. The structural and thermal characteristics of materials were evaluated by using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TG), Derivative Thermogravimetry (dTG), and Differential Calorimetry (DSC). The mechanical properties of polymer films were evaluated through the parameters of impact strength, flexibility, adhesion, and hardness. The results showed that the content of 4.0 wt% BA increased the impact strength of the epoxy polymer film (increased by 38%) and increased the thermal properties of epoxy composite materials (increased by 14%). Combining 4.0 wt% BA and 1.0 wt% NS, the thermal properties of the epoxy composite polymer material increased by 18.5%. The epoxy coating was reinforced with 4.0 wt% BA and 1.0 wt% NS achived high thermal stability with the strongest decomposition temperature at 494 °C.

Resumen en Inglés:

Abstract This study developed PBAT (poly[butylene adipate-co-terephthalate]) biocomposites with 10 wt% and 20 wt% Brazil nut urchin particles by extrusion and injection. TGA showed thermal stability up to 275°C (10 wt%) and 250°C (20 wt%), with degradation peaks near 400°C. XRD indicated maintained crystallinity, with the 10 wt% composite having the highest peak intensity (5254 a.u.). FTIR confirmed molecular interactions through characteristic OH (3442 cm−1) and C=O (1710-1720 cm−1) peaks. SEM revealed better surface integrity at 10 wt%, while 20 wt% showed porosity and poor adhesion. Tensile strength decreased from 9.36 MPa (PBAT) to 7.08 MPa (10 wt%) and 6.7 MPa (20 wt%). Elongation reduced, whereas Young’s modulus increased to 210 MPa (10 wt%) and 316 MPa (20 wt%). Shore D hardness improved by over 40%, but impact resistance dropped by up to 88%. These biocomposites show potential for applications requiring higher stiffness and hardness, contributing to sustainable plastic alternatives.

Resumen en Inglés:

Abstract This article presents a concise review of nanofiber production techniques, materials obtained by innovative technologies to produce nanofibers. The use of nanofibers has evolved significantly due to their unique properties, allowing maximization at the nanometric scale. The large-scale production capacity, simplicity in manufacturing and versatility have increased interest in several areas, especially in pharmaceuticals, for controlled drug release. Different nanofiber manufacturing techniques were explored and how each one can improve medical-pharmaceutical devices, biomaterials, nanotechnology, textile industries, air and water filters, human tissue engineering, among others. It was observed that interest in nanofibers has grown worldwide in research. Despite the advances, challenges remain to optimize production and expand knowledge in the pharmaceutical sector. Future research should focus on more economical and sustainable manufacturing processes, in addition to exploring biodegradable and biocompatible polymers to solve problems in pharmaceutical formulations.