1,721,284 research outputs found
Multifunctional green composites based on plasma-activated and GO-coated dwarf palm fibers
Full text linkIn this work, we propose a green method for decorating natural fibers derived from dwarf palm waste with graphene oxide (GO) sheets. In detail, plasma-treatment was used to activate fiber surface for the subsequent GO-coating, which was performed in water. Poly(butylene adipate-co-terephthalate) (PBAT)-based composites incorporating 50 % of either raw, plasma-modified or hybrid fibers were prepared by compression moulding and thoroughly analysed to investigate the processing-structure-properties relationships of these systems. The outcomes reveal that combining plasma treatment and GO coating enables fabricating green composites with significantly improved mechanical performance (stiffness and tensile strength increments of up to 500 % and 300 %, respectively) and electrical conductivity on the order of 10(-6) S/m
3D wet-electrospun “branch leaf” graphene oxide polycaprolactone fibers structure for enhancing oil-water separation treatment performance in a multi-scale design
No full textSuper-wetting materials have garnered significant attention for the potential to treat oily wastewater due to their selective adsorption and recyclability. In this work, we developed a hierarchical structure of polycaprolactone decorated with branch leaf-like graphene oxide (PCLGO) by wet-electrospinning process. This structure combines a hydrophilic/oleophobic GO anchored into an oleophilic/hydrophobic PCL 3D fiber network. The unique configuration ensures exceptional water diffusion due to the hydrophilic nature of GO, while the hydrophobic PCL fibers enhance the interaction with oil droplets. This synergy promotes oil spreading on the surface and enables superior phase separation of pollutants. The resulting PCLGO structures perform remarkably in separating both water-floating oil and oil-in-water emulsions, achieving an oil adsorption capacity (Qmax) of 28 g/g and an impressive separation efficiency of 99.8 %, with excellent recycling capacity up to 20 cycles. This study provides valuable insights into developing advanced multifunctional materials for water treatment applications and offers a potentially innovative strategy for addressing water treatment challenges
Stable and reusable electrospun bio-composite fibrous membranes based on PLA and natural fillers for air filtration applications
Full text linkToday, air pollution due to fine dust is one of the most critical environmental challenges. To mitigate the potential further environmental impact of air filtration devices, it is essential to explore the use of biodegradable polymers combined with natural fillers, preferably sourced from waste materials, to develop stable, reusable and UV-resistant air filters suitable for outdoor applications. In this work, composite fibrous membranes based on polylactic acid (PLA) and natural fillers were prepared via electrospinning and tested for air filtration applications. Air filtration performances were evaluated at different flow rates, temperature and humidity condition, aiming to simulate outdoor conditions. The addition of 10 wt% of Opuntia Ficus Indica (OFI), Posidonia Oceanica Leaves (POL) or lignin (LIG) particles to PLA solution led to a decrease in fibers diameter increasing membranes filtration performances. PLA/OFI, PLA/POL and PLA/LIG composite membranes exhibited filtration efficiencies of 97.2 %, 99.4 %, 99.6 % for PM3 at a flow rate of 32 L/min, and pressure drops of 114, 103, 105 Pa, respectively. The membranes demonstrated stability maintaining good filtration efficiency across different environmental conditions and after multiple reuse cycles. The addition of OFI and LIG powders also provided effective UV resistance, crucial for ensuring the longevity and performance of air filters exposed to outdoor conditions. These findings underscore the potential of these biodegradable composite membranes for sustainable indoor and outdoor air filtration solutions
Properties-morphology relationships in electrospun mats based on polylactic acid and graphene nanoplatelets
No full textAligned and randomly oriented polylactic acid (PLA) biocomposite nanofiber mats filled with Graphene nanoplatelets (GnP) were prepared by electrospinning. The morphological analysis revealed the successful alignment of the fibers achieved by collecting the mats on a high-speed rotary drum. Furthermore, GnP addition on the polymeric solution leads to an increase of the viscosity with a consequent increment of the fiber diameter. Tensile tests demonstrated that the reinforcing effect of GnP when added to the PLA matrix was more than three times higher in the aligned systems if compared with the respective randomly oriented mats. DSC analysis showed that GnPs were able to slightly increase the crystallinity of the composites acting as nucleating agent. TGA measurements highlighted that the incorporation of GnP in PLA electrospun mats leads to an improved thermal stability of the composites. Both thermal analysis indicate that there is no significant effect of the orientation of the fibers
Electrospun polymeric nanohybrids with outstanding pollutants adsorption and electroactivity for water treatment and sensing devices
Full text linkGraphene oxide (GO) and carbon nanotubes (CNTs) were loaded at different mutual ratios into poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) matrix and electrospun to construct mats that were assessed as smart sorbents for decontaminating water from methylene blue (MB) pollutant, while ensuring the additional possibility of detecting the dye amounts. The results revealed that sorption capacity enhances upon increasing GO content, which is beneficial to wettability and active area. Equilibrium adsorption of these materials is precisely predicted by the Langmuir isotherm model and the maximum capacities herein achieved, ranging from 120 to 555 mg/g depending on the formulation, are higher than those reported for similar systems. The evolution of the structure and properties of such materials as a function of dye adsorption was studied. The results reveal that MB molecules prompted the increase of electrical conductivity of the samples in a dose-dependent manner. Mats containing solely CNTs, while displaying the worst sorption performance, showed the highest electrical performances, displaying interesting changes in their electrical response as a function of the dye amount adsorbed, with a linear response and high sensitivity (309.4 mu S cm-1 mg-1) in the range 0-235 mu g of dye adsorbed. Beyond the possibility to monitor the presence of small amounts of MB in contaminated water and the saturation state of sorbents, this feature could even be exploited to transform waste sorbents into high-added value products, including flexible sensors for detecting low values of pressure, human motion, and so on
Innovative heat assisted solution blow spinning: PVA mats with enhanced thermal stabilization and antimicrobial efficacy
Full text linkSolution Blow Spinning (SBS) has garnered significant attention for its rapid production of fibers from polymeric solutions. However, its efficacy is hindered by the low evaporation rates of aqueous solvents. In a groundbreaking development, we introduce the Heat Assisted Solution Blow Spinning (HA-SBS) system, which, for the first time, enables the one-step production of crosslinked Polyvinyl alcohol (PVA) fibers from an aqueous solution. By incorporating chlorhexidine (CHX) and/or graphene nanoplatelets (GNP) into the starting solution, we formulated four distinct variations. Our results reveal that all HA-SBS-produced systems maintain robust structural integrity and fibrous architecture after water immersion. The inclusion of GNP nanofillers not only enhances the crosslinking level but also significantly boosts mechanical performance. Release tests indicate that HA-SBS membranes effectively decelerate CHX release, providing controlled and sustained antimicrobial efficacy. Notably, CHX-containing membranes exhibit potent antimicrobial activity against both Gram-positive and Gram-negative bacteria. This innovative approach holds great promise for advancing the production of functional fibrous membranes, with broad implications for various applications
Physical properties of green composites based on poly-lactic acid or Mater-Bi® filled with Posidonia Oceanica leaves
No full textThis work focuses on the evaluation of Posidonia Oceanica leaves as effective reinforcing agent for ecofriendly, fully biodegradable polymer composites. Posidonia leaves were washed, ground and sieved in order to achieve two different size distributions and aspect ratios. They were then added to either a stiff or a ductile biodegradable polymer matrix, respectively poly-lactic acid (PLA) and MaterBi® (MB), at two different filler contents (10 wt% and 20 wt%). The materials were fully characterized from a spectroscopic, morphological, rheological, and mechanical point of view. In particular, the outcomes of tensile tests were statistically analyzed by using a Full Factorial Design in order to examine the main effect of type of polymer, filler size and filler content (as well as their mutual interactions) on two properties of great concern, such as elastic modulus and toughness
Processing, structure, property relationships and release kinetics of electrospun PLA/Carvacrol membranes
No full textIn this work, polylactic acid (PLA) membranes at two different carvacrol (CRV) nominal concentration (i.e. 14 wt% and 28 wt%) were prepared via electrospinning technology. The membranes were characterized by scanning electron microscopy, ATR-FTIR and calorimetric measurements as well as tensile tests. Moreover, the release kinetics of CRV in phosphate buffered solution at 37 °C was monitored through UV–Vis measurements and the data were fitted with a power law model. Results indicated that the successful incorporation of CRV in the polymer matrix damaged the fibers morphology but increased all the mechanical parameters investigated (i.e. elastic modulus, tensile strength and elongation). The power law model highlighted that the mechanism of CRV release changed with time from an anomalous release in the first 6 h to a Fickian diffusion mechanism for both the PLA/CRV systems
Nanolimes-based ternary formulations for paper reduction, deacidification and consolidation
No full textSynchronizing the release rates of salicylate and indomethacin from degradable chitosan hydrogel and its optimization by definitive screening design
No full textThree types of ionically crosslinked (with citric acid) chitosan discs were loaded with the highly water- soluble drug, sodium salicylate (SS) and the poorly water-soluble drug, indomethacin (Ind). In separate experiments the hydrated discs were immersed in a de-crosslinking solution comprising of different concentrations of calcium chloride, which induced a controlled erosion of the discs, a process which was optimized to synchronize the release rates of the two drugs over a predetermined period of time. The optimization was accomplished by manipulating six factors: chitosan MW, its amount in the formulation, the concentration of the crosslinker agent, the concentration of the de-crosslinking agent in the dissolution medium, its pH and its temperature. A computerized multifactorial definitive screening design analysis assisted in minimizing the number of experiments. The quotient of the SS to Ind release rates, the difference factor f1, the similarity factor f2 and the combination of f1 and f2 were determined as the experimental responses. The computerized prediction profilers that were used to simulate the contribution of the experimental factors and their effect on the experimental responses led to a successful erodible formulation with a concomitant release of the two drugs over 150 min
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