Resumo em Inglês:

Abstract This study explores the development of biodegradable filaments for additive manufacturing, aiming to create membranes for oil and water separation. Using a mixture of poly (lactic acid) and poly (butylene adipate co-terephthalate) (PLA/PBAT) with additives such as zinc oxide, biocide and carnauba wax. The research evaluates the potential of these materials in membrane prototyping for this application. Characterization techniques such as FTIR, XRD, DSC and tensile strength were employed. The results showed that the addition of the additives did not induce the formation of new bands in the FTIR. However, new diffraction peaks appeared in the composites indicating the presence of the zinc oxide. DSC revealed a double peak in melting and crystallization temperatures and the mechanical tests showed significant influence of additives on tensile strength. The composite filaments proved to be suitable for 3D printing, suggesting their applicability in the manufacture of filter membranes for oil and water separation.

Resumo em Inglês:

Abstract Graphene nanoparticles (GnP) were selected as an alternative reinforcing nanofillers, which enhances the mechanical properties of polypropylene (PP-homo and PP-block copolymer). It may play the role of compatibilizer in polypropylene-graft-maleic anhydride (PP-g-MA) from a double-screw extruder. The effect of GnP loading and the use of the PP-g-MA compatibilizer were studied. The influence on the mechanical properties of tensile strength, elongation at break, IZOD impact strength, and melting temperature in PP-homo and PP-block copolymer were investigated and compared. Their improvement was observed at to a certain amount of 0.3% (by mass) of GnP depending on the substrate nature: homopolymer or block copolymer. The increase from 69.3 J.m-1 to 176.0 J.m-1 corresponds to a 2.5 times rising in IZOD impact resistance for block copolymer. The PP block copolymer has a significant affinity in respect of the presence of graphene and the compatibilizer due to the elastomeric co-monomer present in the block copolymer.

Resumo em Inglês:

Abstract Nanocomposite films from cellulose jute fibers can be promising for application in electronic devices, mainly when silver nanoparticles (AgNPs) are added, which increases their conductivity. This work studied the transmittance, conductivity, and thermal stability of regenerated cellulose films (RCF) by adding AgNPs and plasticizers. Carboxymethylcellulose (CMC), sorbitol, and glycerol plasticizers were incorporated at 15 wt.% and 0.5 wt.% of AgNPs. The resulting materials were studied using Ultraviolet-visible and Fourier Transform Infrared Spectroscopy, electrical analysis using the Van der Pauw method, and thermogravimetry. As a result, an average size of 9 nm for AgNPs was verified. Incorporating AgNP in the films decreased the transmittance by a minimum of 34% compared to pure RCF and reduced thermal stability by at least 10 ºC. Nanocomposites containing plasticizers showed an improved conductivity after incorporating these components, from 10-2 to 10-1 (S/cm).

Resumo em Inglês:

Abstract Fossil-origin plastics have raised great concerns due to their non-biodegradable nature. Biodegradable polymers can be an alternative for these materials’, however they have higher cost. The use of agro-industrial waste in blends with biopolymers can provide cheaper materials’ with improved properties. This study aims to develop low-cost biodegradable materials by extrusion and thermoplastic injection using oat hulls, polybutylene succinate (PBS), and starch. Six formulations with different concentrations of oat hulls (0-56% w/w) were extruded in a single-screw extruder, and then the materials were produced by thermoplastic injection. The extrusion aligned the oat hull fibers, making the material dimensionally stable. The oat hulls enhanced stiffness and reduced material density compared to non-hull counterparts. Besides that, the oat hulls are a low-cost agro-industrial byproduct, and it was possible to produce biodegradable materials with up to 56% hulls and only 20% PBS. These biodegradable materials are environmentally friendly and non-toxic.

Resumo em Inglês:

Abstract This study presents a novel approach to obtaining nano-antimicrobial hybrid material by integrating electrospun nanofibers based on cellulosic biopolymer (BP) associated with antimicrobial agents, specifically silver nanoparticles (AgNPs) and Clavanin A (ClavA), an antimicrobial peptide obtained from the marine tunicate Styela clava. The electrospinning technique produced the blended polyvinyl alcohol:BP nanofibers. Chemical crosslinking was performed to ensure the stability of the nanofibers. The nanofibers had an average diameter of 568 nm for PVA nanofibers and 648 nm for PVA nanofibers functionalized with silver nanoparticles. The nanohybrid material demonstrates significant inhibition zones against Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa, Klebsiella pneumoniae) bacteria. P. aeruginosa exhibits a substantial inhibition zone of 15 mm. Thus, the nanohybrid material was effective against this challenging pathogen. Combining electrospun nanofibers, bacterial cellulose hydrogel, and antimicrobial agents establishes a solution that could combat microbial threats in wound care.

Resumo em Inglês:

Abstract This article details the development of hybrid composites with a PLA matrix filled with coffee husks, potassium feldspar, and Bahia Beige marble. Comprehensive analysis included FTIR, hardness, contact angle, density tests, SEM for microstructural insights, and XRF for optimizing raw material compositions. Also, variance analysis was applied in all results. The study revealed that these biodegradable composites hold promise for sustainable applications. Density variations were noted due to particle compaction, and hardness slightly decreased with coffee husks, attributed to uneven component distribution. Increased hydrophilicity was observed with filler addition. SEM confirmed strong interfacial adhesion, and color consistency was maintained. Notably, coffee husks significantly enhanced the degradation rate of PLA, achieving a 100% higher rate compared to pure PLA. The presence of calcium and potassium minerals offers additional benefits for soil health. The study suggests that thermoformed, multi-layered composite capsules can be fully biodegradable, promoting environmental sustainability in coffee capsule production.

Resumo em Inglês:

Abstract A novel conjugated rod–coil diblock copolymer poly(3-hexylthiophene)-block-poly(furfuryl methacrylate) (P3HT-b-PFMA) has been successfully synthesized for the first time using photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP). This process utilized an organic photoredox catalyst of N-aryl phenoxazine, namely 10-(Perylene-3-yl-10H-Phenoxazine, under 365 nm UV irradiation. The diblock copolymer P3HT-b-PFMA was produced efficiently in a controlled manner, resulting in designed average molecular weights and a narrow polydispersity index. Notably, the furfurylmethacrylate (FMA) monomer derived from biomass-based furfuryl compounds was applied for this controlled polymerization, leading to the formation of conjugated diblock copolymers. The synthesized P3HT-b-PFMA was characterized through 1H-NMR, FT-IR, and GPC methods. Furthermore, the optical and hydrophilic-hydrophobic properties of P3HT-b-PFMA were also evaluated through UV-Vis spectroscopy and contact angle measurements.

Resumo em Inglês:

Abstract In this work, magnetic polymeric microspheres were prepared through the copolymerization of styrene and divinylbenzene in the presence of magnetite synthesized in our laboratory. The effects of magnetite modification with oleic acid, stirring speed, initiator concentration and stabilizer concentration on the particles’ properties were studied. The magnetic microspheres were characterized according to morphology, thermal stability, particle size and distribution, and magnetic properties. The microspheres had spherical shape, micrometric size and superparamagnetic properties. Particle size was mainly affected by stirring speed, while particle size dispersion was strongly affected by initiator and stabilizer concentrations. The saturation magnetization of the microspheres was similar to the values reported in the literature for microspheres with the same content of magnetic material. The modification with oleic acid promoted the incorporation of magnetic material.

Resumo em Inglês:

Abstract Portable electrospinning devices have some advantages over conventional benchtop equipment, such as lower cost, better transportability, ease of operation and flexibility in size, shape and deposition surface, especially for in situ applications, such as wound dressings, drug release and cosmetics. In this work, poly(vinyl alcohol) membranes were produced from aqueous solutions, with different viscosities and at different electric field values, using a portable electrospinning device prototype. Field-emission scanning electron microscopy was used to characterize the morphology of the membranes. The results showed that the prototype allowed the electrospinning of membranes, presenting fiber diameter of 147±11 nm and deposition width of 4,6±0.3 cm, similar to the values obtained with the benchtop device.

Resumo em Inglês:

Abstract The UV-resistance performance of waterborne epoxy coatings with different aminic-curable substances was evaluated to solve the widely known problem of poor weathering resistance of coatings. Samples were evaluated by color and gloss changes, FTIR, thermal properties, and macroscopic morphology. Results indicated that higher aminic values in curing agents degraded faster than lower aminic values (increases of ~3% in delta b and delta E between 5 and 20%). All samples showed a gloss variation varying between 40 and 70 G.U. FTIR and Tg indicated the resin degradation when using curing agents of unmodified aliphatic amine because of its rapid chemical degradation under a UV environment, as confirmed by microscopy images. The curing agents with aminic values between 200 and 300 KOH/g and the equivalent weight of amine hydrogen higher than 120 g/eq showed the best performance in epoxy coatings and good stability against accelerated aging, being promising options for future applications.

Resumo em Inglês:

Abstract Chitosan-based adsorbents have high efficiency in removing heavy metals from water. In this study, the adsorption of Hg2+, Ni2+ and Cu2+ onto chitosan/glutaraldehyde hydrogels were analyzed using the semi-empirical method PM3. Based on thermodynamic analysis of these systems, the adsorption processes were spontaneous, exothermic and highly stable, because all the values ​​of the Gibbs free energy, the enthalpy of formation and the binding energy were negative, on the other hand, each of the systems were analyzed using electrostatic potential maps, where it was observed that the functional groups amino (NH2) and hydroxyl (OH) are the main active sites of the adsorbent. Through an FTIR analysis, the correct cross-linking between chitosan and glutaraldehyde was confirmed, as well as the union of the different cations on the surface of the adsorbent.

Resumo em Inglês:

Abstract Banknotes often have a short lifespan and are frequently removed from circulation due to wear and tear, leading to a significant disposal challenge given the millions of banknotes discarded annually. This study evaluated the utilization of these waste banknotes, primarily composed of cotton fibers, in producing polymer composites. The mechanical and thermal properties, hydrophilicity, and degradation through accelerated aging of composites made from recycled polypropylene (PPR) and banknote residues were evaluated. The results indicated that including banknote waste increased the hydrophilicity of the composites relative to pure PPR and improved mechanical properties against weathering. Notably, composites with 10 wt% banknote content enhanced Young’s modulus and tensile strength, both in weathered and non-weathered conditions. This approach not only offers a potential solution for the disposal of waste banknotes but also aligns with the broader goal of reducing ecological impact and promoting the development of sustainable composite materials.