Search Results (12)

Nanofibers, with their high surface area-to-volume ratio and unique physical properties, hold significant promise for a wide range of applications, including medical devices, filtration systems, packaging, electronics, and advanced textiles. However, their development and commercialization are hindered by several key challenges and hazards. The main issues are production cost and yield, high voltage, clogging, and toxic materials driven by complex production techniques, which limit their adoption. Additionally, there are environmental and health concerns associated with nanofiber production and disposal, necessitating the development of safer and more sustainable processes and materials. Addressing these challenges requires continued innovation in materials science and industrial practices, as well as a concerted effort to balance production, material, and surrounding condition parameters. This study emphasizes the challenges and hazards associated with nanofiber materials and their production techniques, including electrospinning, centrifugal spinning, solution blow spinning, electro-blown spinning, wet spinning, and melt spinning. It also emphasizes biopolymers and recycling as sustainable and eco-friendly practices to avoid harming the environment and human beings. Full article

In this work, the resistance of polylactide-based non-wovens produced by solution blow spinning to environmental factors was investigated. An average contact angle of up to 136° was achieved with an average fiber diameter of 340 nm at the optimal material density and nozzle–substrate distance. When exposed to ultraviolet (UV) radiation, the polylactide non-wovens rapidly lose their hydrophobic properties due to changes in surface morphology resulting from fiber melting. It was demonstrated that the influence of surface structural features on hydrophobicity is greater than that of the material itself. The stability of the wetting properties under UV irradiation was assessed using the derivative parameters of the Owens–Wendt technique, which can serve as an additional method for estimating surface polarity. Full article

New substances and particles appearing in the environment following technological development pose new challenges for separation methods. Moreover, the growing amount of waste also forces us to look for environmentally friendly solutions. One way to create filtration structures with the desired properties is to combine known techniques, thanks to which the advantages of one technique complement the deficiencies and disadvantages of another. Combining the melt-blowing and solution-blowing processes seems to be promising. Fibres created from melt-blowing will provide mechanical strength, while solution-blowing will allow the introduction of nanofibres into the structure with unique filtration and functional properties. Both methods enable working with biodegradable polymers, so the resulting filter can also be environmentally friendly after operation. Our research aimed to check whether combining two fibre production techniques (melt-blown and solution-blowing) is possible and how the joining method will affect the final product. We created a multilayer structure by placing a layer of solution-blowing nanofibres between melt-blown layers, and a mixed structure by simultaneous melt-blowing and solution-blowing. The created multilayer structure was characterised by high filtration efficiency and high-pressure drop. In contrast, the mixed structure achieved a high-quality factor and high mass of deposited droplets per 1 J of energy used for work. Full article

In this study, textile fiber prototypes based on polyester and different Cu nanoparticles (CuNP) content were produced using melt-spinning to obtain bi-component multifilament fibers and melt-blowing to obtain non-woven fabrics. The prototypes were tested against pathogenic microorganisms such as S. aureus, E. coli, and C. albicans. It was shown that bi-component fibers offer excellent protection against pathogens, with up to 99% growth inhibition with 0.5% w/w for S. aureus and E. coli; meanwhile, non-woven fabric only shows activity against E. coli from 0.1% w/w of CuNP. Using different analytical techniques, it was possible to identify that the CuNP were confined exclusively in the outer cover of the bi-component fibers which may be associated with increased antimicrobial activity compared to the fibers in the non-woven fabric. The use of polymeric nanocomposites based on polyester/copper offers an alternative of great interest due to the versatility of the raw material and the high efficiency of copper nanoparticles as an antimicrobial additive. Full article

In this paper Ethylene Propylene Diene Monomer rubber (EPDM) foams were filled with different amounts of paraffin, a common phase change material (PCM) having a melting temperature at about 70 °C, to develop novel rubber foams with thermal energy storage (TES) capabilities. Samples were prepared by melt compounding and hot pressing, and the effects of three foaming methods were investigated. In particular, two series of samples were produced through conventional foaming techniques, involving physical (Micropearl^® F82, MP, Lehvoss Italia s.r.l. Saronno, Italia) and chemical (Hostatron^® P0168, H, Clariant GmbH, Ahrensburg, Germany) blowing agents, while the salt leaching method was adopted to produce another series of foams. Scanning electron microscopy (SEM) and density measurements showed that MP led to the formation of a closed-cell porosity, while a mixed closed-cell/open-cell morphology was detected for the H foamed samples. On the other hand, foams produced through salt leaching were mainly characterized by an open-cell porosity. The qualitative analysis of paraffin leakage revealed that at 90 °C only the foams produced through salt leaching suffered from significant PCM leakage. Consequently, the thermo-mechanical properties were investigated only in samples produced with H and MP. Differential Scanning Calorimetry (DSC) analysis revealed that EPDM/paraffin foams were endowed by good TES properties, especially at higher PCM contents (up to 145 J/g with a paraffin amount of 60 wt%). Tensile and compressive tests demonstrated the addition of the PCM increased the stiffness at 25 °C, while the opposite effect was observed above the melting temperature of paraffin. These results suggest that the EPDM foams produced with H and MP show an interesting potential for thermal management of electronic devices. Full article

In this current work, antimicrobial films based on starch, poly(butylene adipate-co-terephthalate) (PBAT), and a commercially available AgNPs@SiO₂ antibacterial composite particle product were produced by using a melt blending and blowing technique. The effects of AgNPs@SiO₂ at various loadings (0, 1, 2, 3, and 4 wt%) on the physicochemical properties and antibacterial activities of starch/PBAT composite films were investigated. AgNPs@SiO₂ particles were more compatible with starch than PBAT, resulting in preferential distribution of AgNPs@SiO₂ in the starch phase. Infusion of starch/PBAT composite films with AgNPs@SiO₂ marginally improved mechanical and water vapor barrier properties, while surface hydrophobicity increased as compared with films without AgNPs@SiO₂. The composite films displayed superior antibacterial activities against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The sample loaded with 1 wt% AgNPs@SiO₂ (SPA-1) showed nearly 90% inhibition efficiency on the tested microorganisms. Furthermore, a preliminary study on peach and nectarine at 53% RH and 24 °C revealed that SPA-1 film inhibited microbial spoilage and extended the product shelf life as compared with SPA-0 and commercial LDPE packaging materials. The high-throughput production method and strong antibacterial activities of the starch/PBAT/AgNPs@SiO₂ composite films make them promising as antimicrobial packaging materials for commercial application. Full article

In this paper, a novel optical technique for following the progress of the blister copper desulfurization process is presented. The technique is based on the changes observed in the continuous spectrum of the visible–near-infrared (VIS–NIR) radiation that the blister melt emits while the chemical reactions of the sulfur elimination process are taking place. Specifically, the proposed technique uses an optical probe composed of an optical fiber, a collimating lens, and a quartz tube, which is immersed in the melt. This optical probe provides a field of view of the blowing zone where the desulfurization reaction occurs. The experimental results show that the melt VIS–NIR total irradiance evolves inversely to the SO₂ concentration reported by a gas analyzer based on differential optical absorption spectroscopy. Furthermore, the blister copper spectral emissivity as well as the total emissivity observed throughout the process show strong correlation with the sulfur content during desulfurization reaction. Full article

In this work, a multifunctional polymer composite is made using melt-blowing technology from polypropylene (88 wt.%) and poly (ethylene terephthalate) (12 wt.%) with the addition of functional modifiers, that is, 3 g of a superabsorbent polymer and 5 g of a biocidal agent (Biohaloysite). The use of modifiers is aimed at obtaining adequate comfort when using the target respiratory protection equipment (RPE) in terms of microclimate in the breathing zone and protection against harmful aerosols including bioaerosols. The developed production method is innovative in that the two powdered modifiers are simultaneously applied in the stream of elementary polymeric fibers by two independent injection systems. Aerosols of the modifiers are supplied via a specially designed channel in the central segment of the die assembly, reducing the amount of materials used in the production process and saving energy. The results show that the proposed method of incorporating additives into the fiber structure did not adversely affect the protective and functional properties of the resulting filtration nonwovens. The produced nonwoven composites are characterized by SEM, FTIR, and differential scanning calorimetry (DSC). Given their high filtration efficiency at 5%, satisfactory airflow resistance (~200 Pa), very good antimicrobial activity, and excellent water absorption capacity, the obtained multifunctional nonwoven composites may be successfully used in filtering respiratory protective devices. Full article

In order to explore the forming mechanism of the fiber whipping motion in slot-die melt blowing, the turbulent airflow in slot-die melt blowing was measured online with the approach of the Particle Image Velocimetry (PIV) technique. The PIV results visualized the structure of the turbulent airflow and provided the distributions of air velocity components (v_x, v_y, and v_z). Moreover, the PIV results also demonstrated the evolutive process of turbulent airflow at successive time instants. By comparing the characteristics of the turbulent airflow with the fiber whipping path, the PIV results provide a preliminary explanation for the specific fiber whipping motion in slot-die melt blowing. Full article

The intercalation degree of nanoclays in polymeric foamed nanocomposites containing clays is a key parameter determining the final properties of the material, but how intercalation occurs is not fully understood. In this work, energy dispersive X-ray diffraction (ED-XRD) of synchrotron radiation was used as an in-situ technique to deepen into the intercalation process of polymer/nanoclay nanocomposites during foaming. Foamable nanocomposites were prepared by the melt blending route using low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS) with surface treated nanoclays and azodicarbonamide (ADC) as the blowing agent. Foaming was induced by heating at atmospheric pressure. The time and temperature evolution of the interlamellar distance of the clay platelets in the expanding nanocomposites was followed. Upon foaming, interlamellar distances of the nanocomposites based on LDPE and PP increase by 18% and 16% compared to the bulk foamable nanocomposite. Therefore, the foaming process enhances the nanoclay intercalation degree in these systems. This effect is not strongly affected by the type of nanoclay used in LDPE, but by the type of polymer used. Besides, the addition of nanoclays to PP and PS has a catalytic effect on the decomposition of ADC, i.e., the decomposition temperature is reduced, and the amount of gas released increases. This effect was previously proved for LDPE. Full article

The aim of our research was to produce poly(lactic acid) (PLA) fibres with diameters in the micrometer size range, serving as the reinforcing phase in self-reinforced (SR) PLA composites. Nonwoven PLA mats were manufactured by solvent-free melt-blowing technology. Three types of PLA differing in d-lactide content were processed with a productivity as high as 36 g/h. The crystallinity of the PLA microfibres was enhanced by thermal annealing. A 2–3-fold increase in the degree of crystallinity was obtained, as measured by differential scanning calorimetry (DSC). Fibre diameters between 2–14 µm were revealed by scanning electron microscopy (SEM). Static tensile tests were performed on the nonwoven mats, showing the reduced moduli of the annealed fibres due the amorphous relaxation. The PLA mats were processed via the hot compaction technique and formed into SR–PLA composites. The morphological and mechanical properties of the obtained microstructural composites were comprehensively studied. Composites prepared from annealed, thermally more stable PLA nonwoven mats showed superior mechanical properties; the tensile strength improved by 47% due to the higher residual fibre content. Full article

The presented paper concerns scientific research on processing a poly(lactide-co-glycolide-co-trimethylene carbonate) copolymer (PLLAGLTMC) with thermally induced shape memory and a transition temperature around human body temperature. The material in the literature called terpolymer was used to produce smart, nonwoven fabric with the melt blowing technique. Bioresorbable and biocompatible terpolymers with shape memory have been investigated for its medical applications, such as cardiovascular stents. There are several research studies on shape memory in polymers, but this phenomenon has not been widely studied in textile products made from shape memory polymers (SMPs). The current research aims to explore the characteristics of the PLLAGLTMC nonwoven fabric in detail and the mechanism of its shape memory behavior. In this study, the nonwoven fabric was subjected to thermo-mechanical, morphological, and shape memory analysis. The thermo-mechanical and structural properties were investigated by means of differential scanning calorimetry, dynamic mechanical analysis, scanning electron microscopic examination, and mercury porosimetry measurements. Eventually, the gathered results confirmed that the nonwoven fabric possessed characteristics that classified it as a smart material with potential applications in medicine. Full article