Melt Blowing Process Research Articles

Construction of X-Co-tri@SSNF reinforced PPS composite proton exchange membranes and their performance in fuel cells

In this study, we pioneered the introduction of benzophenone (DPK) as a solid solvent into polyphenylene sulfide (PPS) melt-blown, which effectively reduced the PPS melt-blown processing temperature and significantly improved the coefficients of variation of PPS melt-blown nonwoven materials. X-Co-tri@SSNF proton exchange membranes with excellent performance were prepared by functionalized modification of PPS melt-blown fabric as a substrate. The structure and properties of X-Co-tri@SSNF proton exchange membranes were systematically characterized. The results demonstrate that the 1-Co-tri@SSNF PEM exhibited a high proton conductivity of 0.183 S cm−1 at 80 °C and high humidity, significantly higher than the commercial Nafion 117 (0.135 S cm−1). Due to the heat resistance of PPS itself and the continuous dense network structure substrate of PPS nonwoven fabrics as well as the high compatibility with the membrane casting liquid, the hybrid membrane interfaces were tightly connected, so it makes the hybrid membrane perform better in terms of mechanical stability (tensile strength of 36.7 MPa), methanol permeability (4.78 × 10−7 cm2 s−1), selectivity (16.32 × 104 S s cm−3), and thermal stability (thermal decomposition temperature of around 450 °C). In addition, the 1-Co-tri@SSNF membrane electrode module exhibited excellent single-cell performance with an open-circuit voltage of 629.91 V and a peak power density of 96.29 mW cm−2 (162.9 % higher than that of Nafion 117). Therefore, the composite PEM with PPS melt-blown fabric as the matrix has a more environmentally friendly process than the commercial Nafion 117 membrane, a theoretical guidance for advancing the large-scale production of low-cost PEM.

A facial method for constructing superhydrophobic surface by one-step surface etching combined with melt blowing process

It is a challenge to prepare fluorine-free superhydrophobic surfaces by simple methods. In this work, a simple and effective method for constructing a superhydrophobic surface was developed by combining in situ nanofibrillating melt blowing processs and one-step surface etching. Firstly, the randomly stacked meltblown microfibers as microstructure transformed the wetting performance of the surface from hydrophilic to hydrophobic. Then, by tuning the etching time, the outmost nanofibrils within the microfibers were exposed to form nanostructure thereby achieving superhydrophobic performance with a contact angle of 153°. The superhydrophobicity of the as-prepared nonwoven was maintained after various harsh treatments, such as strong acid, strong alkaline, sandpaper abrasion, and ultrasonic washing, showing stable water repellency ability. In addition, the superhydrophobic nonwoven showed promising application in self-cleaning and oil–water separation. Thus, this work not only prepares a superhydrophobic surface but also proposes a new idea for designing a micro-nano hierarchical structure on the surface.

Porous Melt Blown Poly(butylene terephthalate) Fibers with High Ductility and High-Temperature Structural Stability.

In this study, porous poly(butylene terephthalate) (PBT) fibers were produced by melt blowing cocontinuous blends of PBT and polystyrene (PS) and selectively extracting the interconnected PS domains. Small amounts of hydroxyl terminated PS additives that can undergo transesterification with the ester units in PBT were added to stabilize the cocontinuous structure during melt processing. The resulting fibers are highly ductile and display fine porous structural features, which persist at temperatures over 150 °C. Single fiber tensile testing and electron microscopy are presented to demonstrate the role of rapid quenching and drawing of the melt blowing process in defining the fiber properties. The templated highly aligned pore structure, which is not easily produced in solvent-based fiber spinning methods, leads to remarkable mechanical properties of the porous fibers and overcomes the notoriously poor tensile properties common to other cellular materials like foams.

Trap-induced hydro-charging polylactic acid nonwovens with high charge storage capability for stable and efficient air filtration

Under the background of carbon neutrality, eco-friendly biodegradable polylactic acid (PLA) melt-blown nonwovens have been developed in air filtration. Nevertheless, the filtration performance of existing PLA melt-blown nonwovens is in an embarrassing situation and fails to meet the requirement of high efficiency air filters. Here, with controllable doping of N, N′-ethylene bis-stearamide (EBS), and barium titanate (BaTiO3) into PLA, through the melt-blown process, the charge-storage capacity of PLA nonwovens enhanced significantly. By utilizing the hydro-charging technology thereafter, we have prepared hydro-charged PLA/EBS/BaTiO3 nonwovens (HCP-EB) with excellent filtration performances. The doped EBS and BaTiO3 could improve the crystallization and charge storage capacity of PLA during the melt-blown process, thus constructing a large number of interfacial traps between crystalline and amorphous regions, leading to more electric charges captured during the hydro-charging process. The HCP-EB exhibited a high filtration efficiency (99.69 %) for PM0.3, a low pressure drop (27.44 Pa), and superior charge storage stability. Furthermore, the HCP-EB, remained at 99.18 % filtration efficiency after 48 h of treatment at 90 % relative humidity. After 3 months of storage, it still possessed an excellent filtration efficiency (99.02 %). Our work will contribute to the practical application of PLA melt-blown nonwovens in air filters and masks, and inspire the research of next-generation biodegradable electret air filtration materials.

Styrene-ethylene-butylene-styrene (SEBS) melt-blown fibers for oil spill remediation and oil barrier geotextiles

The distinctive oil gelation characteristics of styrene-ethylene-butylene-styrene (SEBS) thermoplastic elastomers were utilized for successful oil spill remediation with a range of different oils. Porous non-woven SEBS mat was fabricated via melt blown processing using a twin-screw extruder with customized blow die. After conducting rotational and capillary rheology investigations, a heightened melt-blowing temperature (300 °C) was applied to achieve an elevated melt flow index of SEBS for the melt-blowing process. Under optimized blowing parameters, a non-woven fabric was obtained consisting of fine fibers featuring an average fiber diameter of 20 μm. The material and oil absorption properties of the engineered SEBS fabric were compared to polypropylene (PP) nonwovens, a widely used material for oil spill mitigation that relies solely on adsorption and capillary forces to separate and immobilize spilled oil. SEBS nonwovens exhibited outstanding absorption and gelation properties for both crude petroleum and mineral transformer oil. Notably, SEBS demonstrated the ability to immobilize oil even under head pressure and at saturation, surpassing the capabilities of PP nonwovens (average fiber diameter 12 μm). This showcases a more efficient and cleaner method for remediating oil spills by effectively separating oil from water through absorption.

Experimental Study of the Airflow Field and Fiber Motion in the Melt-Blowing Process.

The melt-blowing process involves high velocity airflow and fiber motion, which have a significant effect on fiber attenuation. In this paper, the three-dimensional airflow field for a melt-blowing slot die was measured using the hot-wire anemometry in an experiment. The fiber motion was captured online using a high-speed camera. The characteristics of the airflow distribution and fiber motion were analyzed. The results show that the melt-blowing airflow field is asymmetrically distributed. The centerline air velocity is higher than that around it and decays quickly. The maximum airflow velocity exists near the die face, in the range of 130-160 m/s. In the region of -0.3 cm < y < 0.3 cm and 0 < z < 2 cm, the airflow has a high velocity (>100 m/s). As the distance of z reaches 5 cm and 7 cm, the maximum airflow velocity reduces to 70 m/s. The amplitude of fibers is calculated, and it increases with the increase in air dispersion area which has a significant influence on fiber attenuation. At z = 1.5 cm, 2.5 cm, 4 cm, and 5.5 cm, the average fiber amplitudes are 1.05 mm, 1.71 mm, 2.83 mm, and 3.97 mm, respectively. In the vicinity of the die, the fibers move vertically downward as straight segments. With the increase in distance from the spinneret, the fiber appears to bend significantly and forms a fiber loop. The fiber loop morphology affects the velocity of the fiber movement, causing crossover, folding, and bonding of the moving fiber. The study investigated the interaction between the fiber and airflow fields. It indicates that the airflow velocity, velocity difference, and dispersion area can affect the motion of fiber which plays an important role in fiber attenuation during the melt-blowing process.

Non-woven pitch-based carbon fiber electrodes for low-cost redox flow battery

The low-cost and sustainable non-woven carbon fibers produced from petroleum pitch using a melt-blowing process are shown to be an ideal alternative to expensive polyacrylonitrile-based carbon felt electrode material for redox flow batteries.

Effects of Melt-Blown Processing Conditions on Nonwoven Polylactic Acid and Polybutylene Succinate.

This research aimed to prepare nonwovens from polylactic acid and polybutylene succinate using the melt-blown process while varying the melt-blown process parameters, including air pressure (0.2 and 0.4 MPa) and die-to-collector distance (15, 30, and 45 cm). Increasing the air pressure and die-to-collector distance resulted in the production of smaller fibers. Simultaneously, the tensile strength was dependent on the polymer, air pressure, and die-to-collector distance used, and the percentage elongation at the break tended to increase with an increasing die-to-collector distance. Regarding thermal properties, the PBS nonwovens exhibited an increased level of crystallinity when the die-to-collector distance was raised, consistent with the degree of crystallinity obtained from X-ray diffraction analysis. Polylactic acid could be successfully processed into nonwovens under all six investigated conditions, whereas nonwoven polybutylene succinate could not be formed at a die-to-collector distance of 15 cm. However, both polymers demonstrated the feasibility of being processed into nonwovens using the melt-blown technique, showing potential for applications in the textile industry.

Effect of Polybutylene Succinate Additive in Polylactic Acid Blend Fibers via a Melt-Blown Process.

This work aimed to study the influence of the polybutylene succinate (PBS) content on the physical, thermal, mechanical, and chemical properties of the obtained polylactic acid (PLA)/PBS composite fibers. PLA/PBS blend fibers were prepared by a simple melt-blown process capable of yielding nanofibers. Morphological analysis revealed that the fiber size was irregular and discontinuous in length. Including PBS affected the fiber size distribution, and the fibers had a smoother surface with increased amounts of added PBS. Differential scanning calorimetry analysis (DSC) revealed that the crystallization temperature of the PLA sheet (105.8 °C) was decreased with increasing PBS addition levels down to 91.7 °C at 10 wt.% PBS. This suggests that the addition of PBS may affect PLA crystallization, which is consistent with the X-ray diffraction analysis that revealed that the crystallinity of PLA (19.2%) was increased with increasing PBS addition up to 28.1% at 10 wt% PBS. Moreover, adding PBS increased the tensile properties while the % elongation at break was significantly decreased.

Influence of Rheological and Morphological Characteristics of Polyhydroxybutyrate on Its Meltblown Process Behavior.

Polyhydroxybutyrate (PHB) is a promising biopolymer. However, processing PHB in pure form in thermoplastic processes is limited due to its rapid degradation, very low initial crystallization rate, strong post-crystallization, and its low final stretchability. In this article, we screened commercial PHBs for morphological characteristics, rheological properties, and "performance" in the meltblown process in order to reveal process-relevant properties and overcome the shortcoming of PHB in thermoplastic processes for fiber formation. An evaluation of degradation (extruded (meltblown) material vs. granules) was performed via rheological and SEC analysis. The study revealed large differences in the minimum melt temperature (175 up to 200 °C) and the grade-dependent limitation of accessible throughput on a 500 mm plant. The average fiber diameter could be lowered from around 10 μm to 2.4 μm in median, which are the finest reported values in the literature so far. It was found that the determination of the necessary process temperature can be predicted well from the complex shear viscosity. Different to expectations, it became apparent that a broader initial molar mass distribution (>8) is suitable to overcome the state-of-the art limitations of PHAs in order to stabilize fiber formation, increase the productivity, and obtain better resistance towards thermal degradation in process. Accordingly, longer polymer chain fractions could be more affected by degradation than medium and short polymer chains in the distribution. Further, a low initial narrow distributed molar mass resulted in too brittle fabrics.

Thermoplastic elastomer melt-blown fiber mats for oil spill remediation: Fabrication, oil uptake, and gel formation studies

Melt-blown fibers, featuring porous structures with designed wetting characteristics can provide superior oil/water separation performance. The core objective of this work was to design a material that provides excellent oil/water selectivity for oil spill remediation. For this, the selective oil gelation properties of styrene-ethylene-butylene-styrene (SEBS) and the enhanced surface area provided by melt-blown mats was leveraged to achieve exceptional oil/water selectivity. Nonwoven mats based on SEBS were fabricated with a twin-screw extruder equipped with a custom-engineered melt-blowing die. To address the inherent low melt flow index (MFI) of SEBS, which presents challenges in the melt-blowing process due to decreased stretchability, high MFI polypropylene (PP) was incorporated as a blending additive. Next, the impact of blending polypropylene with SEBS on melt-blowing processability and fiber quality was studied. The inclusion of 10 wt% PP in SEBS considerably enhanced fiber melt-blowing processability, resulting in a more extensive and evenly spread fiber stream. Further analysis of this fiber composition in terms of oil and water interaction revealed superior oil uptake capacity. Moreover, the increased surface area of SEBS-based fibers enhanced their interaction with oil, resulting in the effective formation of a semi-solid gel. Notably, the generated gel established a barrier that successfully limited further oil dispersion even when the material reached its saturation point. This demonstrated a markedly superior oil immobilizing performance in comparison to polypropylene melt-blown fibers.

Development of Nano-Sized Copper-Deposited Antimicrobial Air Filters Using a Mixed Melt-Blown Process.

Air purification devices, such as air purifiers, provide fresh air by filtering out airborne pollutants, dust, and other harmful substances using various filter systems. While air filters are generally effective in filtering pollutants such as dust, they encounter a challenge when filtering harmful microorganisms such as mites, bacteria, mold, and viruses. These microorganisms, which are present in public transport and public indoor spaces, tend to proliferate on the surface of the filter media, eventually reintroducing themselves into the air or causing unpleasant odors. To address this issue, herein, copper particles were prepared as one masterbatch and deposited on polypropylene (PP) pellets through plasma vacuum deposition to effectively filter dust and microorganisms and prevent their growth on the surface of the filter media. After adding 3-10 wt.% of the masterbatch to conventional PP pellets to fabricate a filter media, the distribution of copper on the surface of the filter media was observed through a scanning electron microscope. To verify the safety and effectiveness of the antimicrobial material, the filter media containing antimicrobial particles was tested using Escherichia coli (E. coli) and Staphylococcus aureus through a filter emission test.

Soft, strong, and breathable polylactic acid/polyethylene glycol microfibrous membranes with a fluffy alignment structure for skin contactor

Polylactic acid (PLA) microfibrous membranes, having high comfort and wearability features, have attracted considerable research interest for applications involving skin contactors. However, the poor softness and low strength of these membranes are the major challenges that prevent their large-scale fabrication and application. Herein, an advanced strategy for preparing a soft, strong, and breathable polylactic acid/polyethylene glycol (PLA/PEG) microfibrous membrane using an in situ drafting-assisted melt-blowing process has been developed. The introduction of PEG significantly improved the crystallization and plasticization of the PLA chain molecules, thus promoting the perfect crystallinity of the PLA phase. Benefiting from the synergy of the PEG and the drafting process, the prepared PLA/PEG microfibrous membranes exhibited a fluffy structure wherein the air permeability increased to 142.5 mm/s with the increase in DCD to 37 cm. Meanwhile, the PLA/PEG microfibrous membranes exhibit optimized anisotropic softness performance: a smaller maximum resistance of 0.13 N in the machine direction and a larger maximum resistance of 1.8 N in the cross direction were obtained in comparison with conventional membranes. This suggests the tremendous potential for using the fabricated membranes in flexible, breathable, and wearable skin contactors.

A novel investigations on medical and non-medical mask performance with influence of marine waste microplastics (polypropylene)

The entire human race is struggling with the spread of COVID-19. Worldwide, the wearing of face masks is indispensable to prevent such spread. Despite numerous studies reporting on the fabrication of face masks and surgical masks to reduce spread and thus human deaths, this novel work is considered the marine waste of microplastics, namely Polypropylene (PP) polymer, used to fabricate non-woven fabric masks through the melt-blown process. This experimental work aims to maximize the mask's quality and minimize its fabrication cost by optimizing the melt-blown process parameters and using microplastics. The melt-blown process was used to make masks. Parameters such as extruder temperature, hot air temperature, melt flow rate, and die-to-collector distance (DCD) were investigated as independent variables. The quality of the mask was investigated in terms of bacterial filtration efficiency (BFE), particle filtration efficiency (PFE), and differential pressure. The Taguchi L16 orthogonal array and Taguchi analysis were employed for experimental design and statistical optimization, respectively. The results reveal that the higher BFE and PFE are recorded at 96.7 % and 98.6 %, respectively. The surface morphological investigation on different layers ensured the fine and uniform porosity of the layers and exhibited minimum breath resistance (a low differential pressure of 0.00152 kPa/cm2). Hence the chemically treated marine waste microplastics improved the masks' performance.

Nanoval Technology—An Intermediate Process between Meltblown and Spunbond

The idea of "Nanoval technology" origins in the metal injection molding for gas atomization of metal powders and the knowledge of spunbond technologies for the creation of thermoplastic nonwovens using the benefits of both techniques. In this study, we evaluated processing limits experimentally for the spinning of different types of polypropylene, further standard polymers, and polyphenylene sulfide, marked by defect-free fiber creation. A numerical simulation study of the turbulent air flow as well as filament motion in the process visualized that the turnover from uniaxial flow (initial stretching caused by the high air velocity directed at the spinning die) to turbulent viscoelastic behavior occurs significantly earlier than in the melt-blown process. Modeling of the whole process showed that additional guide plates below the spinneret reduce the turbulent air flow significantly by regulating the inflow of secondary process air. The corresponding melt flow index of processible polymer grades varied between 35 g·10min-1 up to 1200 g·10min-1 and thus covering the range of extrusion-type, spunbond-type, yarn-type, and meltblown-type polymers. Hence, mean fiber diameters were adjustable for PP between 0.8 and 39.3 μm without changing components of the process setup. This implies that the Nanoval process enables the flexibility to produce fiber diameters in the typical range achievable by the standard meltblown process (~1-7 μm) as well as in the coarseness of spunbond nonwovens (15-30 μm) and, moreover, operates in the gap between them.

Research into the Aerodynamic Attenuation of Hot-Melt Adhesive Fibers Produced by Multihole Melt-Blowing Nozzles

Air consumption in the melt-blowing process represents one of the major costs involved in the production of thin fibers. In the present work an experimental study is conducted on two multihole melt-blowing nozzles for manufacturing styrene–butadiene–styrene based hot-melt adhesive fibers in order to assess their fiber attenuation capability. With this purpose in mind, fiber diameter, fiber temperature, fiber bending, and air velocity were measured experimentally, and the steady-state quasi-one-dimensional longitudinal momentum equation of the slender fiber was integrated numerically in the nozzle postextrusion region and solved for aerodynamic force prefactor K, as it appears in Matsui’s drag coefficient correlation. A measure of fiber attenuation efficiency is proposed in terms of prefactor K and other nozzle geometrical and process operating parameters, which indicates the capacity of the nozzle to produce thin fibers with low air consumption. The results indicate that increasing nozzle air tilt angle, prefactor K, and air–polymer kinematic viscosity ratio in turn increases fiber attenuation efficiency. Working conditions are provided for each nozzle design that allow thin hot-melt-adhesive melt-blown fibers to be produced in a cost-effective manner. Furthermore, a formula is provided for estimating the melt-blown fiber attenuation rate in terms of multihole nozzle geometrical and process operating parameters. The results obtained in this work will help to reduce unnecessary energy consumption of melt-blowing equipment.

Analysis of crystallization during polypropylene melt-blown fiber formation

Melt-blown nonwovens with randomly distributed micron fibers are widely used because of their excellent properties such as high porosity and high filtration efficiency. It is necessary to study the crystallization behavior of the polymer during the melt-blowing process because crystallization affects the formation and properties of the melt-blown fibers. In this study, the nonisothermal crystallization under high-speed cooling conditions and the isothermal crystallization on the collector in the melt-blowing process were investigated. The thermal history of polypropylene during the melt-blowing process was restored by flash differential scanning calorimetry tests. The results showed that the polymer hardly crystallized during the high-speed cooling process from the spinneret to the collector in the case of considering the temperature. The air pressure promoted the crystallinity of melt-blown fibers. The shear effect of the airflow field was considered the main factor affecting the crystallization of melt-blown fibers. The results were beneficial to the establishment of the melt-blowing micro-theoretical model and the control of the final performance of the melt-blown fibers.

Study on the structure and filtration properties of intercalated melt blown nonwoven materials

Based on the traditional melt blown process, PET high crimp elastic staple fibers were added to construct an intercalated melt blown two-component filter material. The changes in structure and filter performance of the material before and after intercalation, and whether the intercalation rate had any effect on these changes were analyzed in this paper. The results showed that the intercalation operation was carried out to solve the problems of poor compression resilience of single melt blown nonwoven material and high filtration resistance of existing filtration materials. A multivariate nonlinear model was developed in this paper to investigate the variation of the product structure under different technological parameters, and a mathematical expression between them was given. A random forest model was used to investigate the variation of product performance under different product structures. Using a combination of multivariate nonlinear model and random forest model, the values of the technological parameters, when the filtration performance was maximum were explored. It can be used as a guide for melt blown nonwoven material production.

Study on the microfiber attenuation in melt-blowing airflow field

Melt blowing (MB) is a process for producing microfiber or nanofiber using high-velocity air to attenuate the polymer jet. Compared to research on the melt-blowing airflow field analysis, the melt blown die optimization, and new materials development, little work has been done on fiber attenuation and whipping in the melt-blowing process. In this study, the airflow field distribution and turbulence fluctuation of the melt-blowing die are investigated using numerical simulation. The fiber motion process is simulated with the bead-viscoelastic element model and obtained using the high-speed camera. The underlying mechanisms leading to melt-blowing fiber attenuation have been discussed. The results show that the airflow field can be separated into three regions. The turbulent fluctuations in Regions I are related to the fiber whipping in the melt-blowing process. The fiber motion in Regions II and III are unsteady, resulting in higher fiber attenuation. Region II is the main zone of fiber attenuation where the fiber whipping increases and the drawing ratio is the largest. The fluctuation of air velocity causes fiber whipping which plays an important role in fiber attenuation. Experimental results of fiber diameter reduction and fiber motion are consistent with the simulation results.

Analysis of the oscillations induced by a supersonic jet applied to produce nanofibers

High-performance fibers are key components for enhancing the mechanical properties of composite materials. The development of high strength nanofibers augurs the production of new nano-composites with outstanding features. However, the robust production of continuous glass nanofibers that can be feasible processed for efficiently manufacturing nanocomposites is still challenging. Recently, Cofiblas (Continuous Fiberizing by Laser melting and Supersonic dragging) was demonstrated as a technique capable of producing continuous glass nanofibers with unlimited length. Cofiblas process has some similarities with the widely known melt blowing technique for the production of polymeric fibers. In both techniques, the design of the gas nozzle is key to ensure the feasibility of the process since the turbulences of the gas jet may induce strong whipping of the filament.This paper gives novel experimental evidences on the correlation of the supersonic gas jet instabilities with the oscillation of the filament in the melt-blowing and Cofiblas processes, relating these oscillations with the presence of shock waves and unsteadiness in the flow, and gives valuable insight into the use of supersonic jets in the melt blowing process as an effective approach for the formation of nanofibers. A thin 3D-axisymmetric model in OpenFOAM® was put to test by comparing the performance of different solvers which were validated by flow visualization of the exit jet using digital holography (DH). In order to perform a realistic and thorough validation, we simulated the optical measurements of the flow from the CFD simulations of the mass density by Abel transform and numerical differentiation. The application of digital holography as the flow visualization technique makes possible both a precise validation of the density maps obtained from the Abel transformation of the 2D-alike results, and the analysis of the shockwave pattern in the air jet. Conversely, the numerical reconstruction of time-averaged holograms is employed to detect unsteadiness in the flow and to analyze the fiber oscillation, which is essential to assess the stability of the process. Lastly, the analysis and comparison of the vibration of the filament using the basic design and the optimized nozzle demonstrates a clear influence of the shock waves and flow unsteadiness in the stability of the filament.