Melt Blowing Research Articles

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.

Decomposition Behavior of Stereocomplex PLA Melt-Blown Fine Fiber Mats in Water and in Compost

This study introduces systematic and comparative investigations of various PLA fine fiber mats prepared by melt blowing. A series of PLLA and PDLA melt-blown fibers from various L and D enantiomers blends were produced. Their morphological, mechanical, and thermal properties were studied, and their decomposition in water and compost was investigated. It was found that the 1:1 ratio blend with stereocomplex crystals had an 80% lower average fiber diameter, 60% higher specific strength and better thermal stability than the PLLA and PDLA fiber mats. In the case of composting, the crystalline peak melting temperature, crystallinity, and thermogravimetric decomposition temperatures marginally decreased after 14 days. The high surface of the fine fiber mats played a crucial role in fast decomposition, as they entirely disintegrated in less than only 40 days. In the case of water, the homocrystalline domains were more susceptible to hydrolysis than the stereocomplex ones. All the PLA fiber mats underwent decomposition and extensive disintegration for 70 days in water. Hydrolysis reduced the amorphous and crystalline fraction of the fibers via surface and bulk erosion, while the decomposition of stereocomplex-crystalline-rich domains mainly exhibited surface erosion. Findings revealed that high porosity and the high surface area of PLA melt-blown fine fiber mats undergo fast decomposition in compost and in water.Graphical

Development and Performance Evaluation of Polytetrafluoroethylene-Membrane-Based Automotive Cabin Air Filter.

A high-efficiency, long-life cabin filter unit is required for the effective purification of the air inside a vehicle. However, conventional cabin air filters that utilize electrostatic effects are less efficient and less effective owing to environmental factors. Polytetrafluoroethylene (PTFE) membranes exhibit a high porosity and surface-to-surface dust-removal performance, and maintain a stable pressure drop, indicating their good potential as filter materials. Therefore, in this study, the use of PTFE membranes for the fabrication of automobile filters and the filtration performance of the filters were examined. To this end, first, the properties of PTFE membranes mainly used in HEPA air conditioning filters and those of membranes used as vehicle cabin filters were compared. Next, the thickness, weight, stiffness, pore size, and filtration performance characteristics of filter media fabricated by blending melt-blown (MB) nonwoven, PTFE membranes, and supporting nonwoven into a total filtration layer were compared and analyzed. Lastly, the environmental change durability performance of the automobile cabin filter based on PTFE membrane and the results of the test after the installation of the filter in a vehicle were demonstrated.

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.

The effect of process parameters on the properties of elastic melt blown nonwovens: Air pressure and DCD

AbstractAn elastic masterbatch and elastic melt blown nonwovens are prepared based successively on styrene‐ethylene/butylene‐styrene (SEBS) and polypropylene (PP) blend. The phase separation morphology, rheological properties and crystal structure of the elastic masterbatch are investigated. The results show that a compatible and stable structure is obtained in molten SEBS and PP blend with excellent mobility in the temperature range of 210–230°C. The crystallization of PP slows down resulting in a finer structure due to the restriction of the SEBS network structure with rarely change of crystalline structure. The relationship between process parameters and properties of the elastic nonwoven is also studied in detail. Air pressure and die to collector distance (DCD) have discernible effects on fiber diameter and bonding between fibers, further influencing the performances of nonwovens including porosity, tensile strength and elastic recovery. Elastic recovery is shown to be significantly more affected by DCD than by air pressure.

A bioinspired strategy to construct dual-superlyophobic PPMB membrane for switchable oil/water separation

Separation membranes with under-liquid dual-superlyophobicity have attractive features owing to their switchable separation of oil/water emulsions and mixtures. However, due to the thermodynamic contradiction, there are great challenges in the preparation of underwater superoleophobic and underoil superhydrophobic membranes. Herein, we report a bioinspired accurate-deposition strategy to fabricate the under-liquid dual-superlyphobic polypropylene melt blown (PPMB) membrane integrated with photocatalysis self-cleaning property. For the first time, we found that UV oxidized gallic acid (UGA) can react with polyethyleneimine (PEI) rapidly to form unique coral-like three-dimensional micro-/nanoscale structures, which have a vital effect on the membrane under-liquid dual-superlyophobicity. Meanwhile, using UGA/PEI coating as an intermediate adhesive layer, a novel, green and fast coating method for tightly anchoring titanate nanotubes (TNTs) on the PPMB membranes was developed. Only driven by gravity, the membrane showed extraordinary ability for switchable oil/water mixtures separation with high fluxes above 12,000 L m−2 h−1, and high separation efficiencies all greater than 99.9%. For switchable separation of emulsions, the as-prepared membrane still performed a high permeating flux above 2500 L m−2 h−1 under gravity. Moreover, when the membrane was fouled by continuous surfactant-stabilized emulsions, the photocatalysis self-cleaning property made the regeneration of the membrane green and environmentally friendly.

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.

Preliminary Study of the Effect of Secondary Airflow on Fiber Attenuation During Melt Blowing

In order to enhance the fiber attenuation during the melt-blown process, a pair of air nozzle, which could erupt airflow as secondary airflow, below the spinning die was arranged and used. Firstly, the effect of applying secondary airflow on the whole airflow was explored by Computational Fluid Dynamics (CFD) simulation. The simulation results demonstrate the interactive relationship between the primary airflow from the spinning die and the secondary airflow. Then, the air velocity of the whole airflow at conditions of with and without secondary airflow was experimental verified. Finally, the effect of secondary airflow on the fiber diameter and the fiber evenness was investigated by a spinning experiment. The spinning results reveals that the application of secondary airflow does not certainly enhance the fiber attenuation. The fiber diameter decreases only when the inlet velocity of secondary airflow is higher than a critical value. In addition, the spinning experiment indicates that the application of secondary airflow improves the evenness of fiber.

Behavior of melt electrospinning/blowing for polypropylene fiber fabrication

AbstractThe fabrication process of polymer fibers has been analyzed in various ways, and several studies have been conducted to develop new processes and optimize existing ones. Several studies have been conducted on the electrospinning process, which can easily fabricate nanofibers, and the development of materials manufactured through electrospinning has also been investigated. However, research on the nanofiber fabrication and processing of thermoplastic polymers, such as polypropylene (PP), polyethylene and polyethylene terephthalate, is relatively lacking. Therefore, research on nanofiber fabrication is essential. In this study, PP fibers were successfully manufactured through a melt electrospinning/blowing process, which combined melt blowing and electrospinning. To analyze the melt electrospinning/blowing process, the dynamic behavior of the spinning process was observed using a charge‐coupled device camera in real time, and the effects of the different spinning conditions were compared and analyzed. As the hot air or high voltage was increased, the spinning jet area tended to increase. In addition, the average diameter of the fabricated fibers tended to decrease as a high voltage was applied at a hot air pressure of 0.01 MPa; conversely, the average diameter tended to increase at a hot air pressure of 0.03 MPa. A similar trend was observed for the tensile stresses in the PP web fabrics. The polymer fibers produced by this melt electrospinning/blowing process can be applied as a production process for nanomembranes, filters and battery separators. © 2022 Society of Industrial Chemistry.

Development of (TiO2-ZnO)/LDPE based active nanocomposite films and detection of migration to minced beef during storage using response surface methodology

In the current research, titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles using ethylene ethyl acrylate as compatibilizer are incorporated into low-density polyethylene (LDPE) to generate active nanocomposite films (ANFs) using melt blowing technique. The film properties such as colour, thickness, mechanical and thermal properties, surface morphology, and molecular composition were analyzed. Subsequently, minced beef samples were packed with ANFs, and migration was determined in 7-days storage period at 1 °C, 7 °C, and −18 0C. The migration characteristics were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) at these 3 different temperature applications. The SEM results indicated that metal oxides had a substantially homogenous distribution in the polymer matrix, but agglomerates were formed in some regions. The Ti and Zn nanoparticles migrated to minced beef were significantly affected by the independent variables. The amounts of Ti and Zn migrated into minced beef samples ranged from 21.37 to 48.15 ppm and 11.01 and 52.74 ppm, respectively. In general, migration from Ti nanoparticles was greater compared to Zn nanoparticles. As a result, it has been demonstrated that TiO2 and ZnO nanoparticles are good alternatives to functionalizing food packaging film.

Multiphase CFD Modeling and Experimental Validation of Polymer and Attenuating Air Jet Interactions in Nonwoven Annular Melt Blowing.

In annular melt blowing, fiber formation is achieved by accelerating a molten polymer via drag forces imparted by high velocity air that attenuates the polymer jet diameter. The interactions at the polymer-air interface, which govern the motion of the jets and impact the resulting fiber characteristics, are important but not well understood yet. This work details the development and validation of a multiphase computational fluid dynamics (CFD) model to investigate these interactions and the effects of three key melt blowing process parameters (polymer viscosity and throughput, and air velocity) on two critical fiber attributes - whipping instability and fiber diameter. Simulation results highlighted that whipping instability was driven by the polymer-air velocity differential, and the fiber diameter was primarily modulated by polymer throughput and air velocity. The CFD model was validated by modulating the polymer and air throughputs and analyzing the fiber diameter experimentally. Empirical results showed good agreement between fabricated and model-estimated fiber diameters, especially at lower air velocities. An additional CFD simulation performed using a melt blowing nozzle geometry and process parameters described in literature also confirmed good correlation between model estimates and literature empirical data.

Experimental and Simulation Investigation on the Effect of Slot Angle on the Flush Sharp Die Performance during Melt Blowing

Experimental and Simulation Investigation on the Effect of Slot Angle on the Flush Sharp Die Performance during Melt Blowing

Development and characterization of triclosan coated heat and moisture exchange filter for ventilation therapy

An indigenous heat and moisture exchange filter has been developed using an open cell reticulated hygroscopic impregnated polyurethane foam and polypropylene nonwoven to maintain heat and moisture exchange and bacterial filtration efficiency respectively. Also, the spun bond polypropylene nonwoven is treated with an optimized concentration of biocide (triclosan-5gpl) mainly on the 1 st contact layer of ventilator gas using padding mangle in 2 dips/2 nips method for better antibacterial efficiency. Three different polypropylene made nonwoven materials [spunbond (SB), meltblown (MB) and needle-punched (NP)] are stacked in different layer arrangement and evaluated for their efficiency in filtering bacteria. The five- layered composite filter (SB-MB-NP-MB-SB biocide treated) with double layers of meltblown and spunbond treated with biocide, in addition to the needle-punched middle layer, shows a bacterial filtration of 99.9% along with excellent antimicrobial properties and acceptable pressure drop. The developed biocide-coated multilayer composite filter provides comfortable and ideal humidification to the users besides delivering excellent antimicrobial activity. This developed filter will be an alternative to existing commercial filters, without any compromise, and having all the inherent properties.

Single-Side Superhydrophobicity in Si3N4-Doped and SiO2-Treated Polypropylene Nonwoven Webs with Antibacterial Activity

Meltblown (MB) nonwovens as air filter materials have played an important role in protecting people from microbe infection in the COVID-19 pandemic. As the pandemic enters the third year in this current global event, it becomes more and more beneficial to develop more functional MB nonwovens with special surface selectivity as well as antibacterial activities. In this article, an antibacterial polypropylene MB nonwoven doped with nano silicon nitride (Si3N4), one of ceramic materials, was developed. With the introduction of Si3N4, both the average diameter of the fibers and the pore diameter and porosity of the nonwovens can be tailored. Moreover, the nonwovens having a single-side moisture transportation, which would be more comfortable in use for respirators or masks, was designed by imparting a hydrophobicity gradient through the single-side superhydrophobic finishing of reactive organic/inorganic silicon coprecipitation in situ. After a nano/micro structural SiO2 precipitation on one side of the fabric surfaces, the contact angles were up to 161.7° from 141.0° originally. The nonwovens were evaluated on antibacterial activity, the result of which indicated that they had a high antibacterial activity when the dosage of Si3N4 was 0.6 wt%. The bacteriostatic rate against E. coli and S. aureus was up to over 96%. Due to the nontoxicity and excellent antibacterial activity of Si3N4, this MB nonwovens are promising as a high-efficiency air filter material, particularly during the pandemic.

Large-scale preparation of polylactic acid/polyethylene glycol micro/nanofiber fabrics with aligned fibers via a post-drafting melt blown process

Polylactic acid (PLA) micro/nanofiber fabrics with good biodegradability and biocompatibility have wide applications in the medical protective field. However, the poor flexibility, high brittleness, and insufficient mechanical properties of PLA micro/nanofiber fabrics remain challenging. Herein, a polylactic acid/polyethylene glycol (PLA/PEG) micro/nanofiber fabric with aligned fibers was successfully prepared by an inexpensive and straightforward post-drafting melt blown process. The experimental results showed that PEG can reduce the Tg of PLA, improve the mobility of PLA molecular chains, reduce the complex viscosity of PLA/PEG blends, and play a role in plasticization. The PLA/PEG micro/nanofiber fabrics had an aligned micro/nanofibrous structure, and the average fiber diameter was easily adjusted from 10.7 to 4.9 μm by tailoring the melt blown process parameters, i.e., die temperature and hot air temperature. Moreover, the breaking tensile strength increased from 45.06 to 78.73 N in the machine direction (MD), while it increased from 11.87 to 21.89 N in the cross direction (CD), which means that the breaking tensile strength was enhanced significantly by adjusting the die temperature and hot air temperature. Furthermore, the prepared samples showed a high softness score of 82.7, a large synthetic blood contact angle of 125.7°, and an excellent bursting strength of 58.5 N. These PLA/PEG micro/nanofiber fabrics with aligned fibers are ideal candidates for medical protective applications such as surgical gowns, protection suits, masks, and medical bandages.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10965-022-03184-2.

Development of single‐polypropylene composites interleaved with MWCNT‐doped melt‐blown fine fiber mats

AbstractIn this article, we demonstrate fabricating polypropylene (PP)/multiwalled carbon nanotube (MWCNT) nanocomposite fiber veils and use them as interleaves in single‐polymer composites (SPCs) to enhance their thermal and mechanical properties. With this regard, we produced a hierarchical composite structure made of a film, a woven fabric and a fine fiber mat made of the same polymer. The nanocomposite fiber mats were generated by melt‐blowing. Results implied that incorporating MWCNT increased the viscosity of the melt blowing grade PP resin. Increasing MWCNT content increased the average fiber diameter and pore size by 2.1‐fold and 2.5‐fold, respectively. Incorporating MWCNT enhanced the melt‐blown (MB) fiber mat's specific strength by 78% and improved the thermal stability. We generated multiscale SPCs by film‐stacking, for which we applied a PP film as a matrix, a PP‐woven fabric as the primary reinforcement, and the MB fiber mats as interleaves. The SPC's tensile modulus was improved by 37% by the interleaving. Our findings implied that the MWCNT‐doped PP fiber mat interleaving provides a robust interfacial adhesion and higher damage tolerance under tensile load. Master curves were constructed from dynamic mechanical analysis frequency sweep tests based on the time–temperature superposition principle. The storage modulus increased by 33%, while the tanδ decreased around 10% with PP/MWCNT fiber mat interleaving. The developed multiscale SPC with MWCNT fiber mat interleaving veils may be easily integrated into engineering composite applications due to its cost‐efficiency, fair recycling, straightforward processing, enhanced stiffness, and interfacial adhesion.

Polylactic acid/UV-crosslinked in-situ ethylene-propylene-diene terpolymer nanofibril composites with outstanding mechanical and foaming performance

Polylactic acid (PLA) is a promising biomass and biodegradable polymer but suffers from its brittle feature and poor foaming ability. Thus, many ductile polymers have been used to modify PLA through compounding. Although some of them can improve the toughness, the strength and rigidness of PLA are seriously scarified due to the large dosage, poor dispersion, and see-island structures. Herein, UV-crosslinking-assisted in-situ fibrillation was developed to fabricate ethylene-propylene-diene terpolymer (EPDM) nanofibril-reinforced PLA composites. Twin-screw compounding followed by melt blowing was used to stretch EPDM phase into nanofibrils, while UV-crosslinking was proposed to stabilize the EPDM nanofibrils in the final PLA/EPDM composites. Thanks to UV-crosslinking, EPDM nanofibrils with an average diameter of 94.3 nm were achieved in PLA. Due to the heterogeneous nucleating effect of UV-crosslinked EPDM nanofibrils, the crystallization rate of PLA was significantly enhanced, and refined crystal morphology with fibrous structures was obtained. Surprisingly, merely 3 wt% of UV-crosslinked EPDM nanofibrils remarkably enhanced the mechanical properties of PLA. The tensile toughness and impact strength were increased by 620% and 440%, respectively, without sacrificing strength and rigidness. Moreover, the UV-crosslinked EPDM nanofibrils also significantly improved the foaming ability of PLA. The PLA/UV-crosslinked EPDM foam with an expansion ratio of up to 28-fold was achieved for the first time by mold-opening microcellular injection molding. With the presence of UV-crosslinked EPDM nanofibrils, the expansion ratio and cell population density of the foams can be increased by 470% and 5 orders of magnitude, respectively. Owing to the super-high expansion ratio and unique micro/nanoscale structures on cell walls, the 28-fold expanded PLA/EPDM foam exhibited outstanding thermally insulating performance with a thermal conductivity of as low as 26.3 mW/m∙K.

Analysis of polymer jet motion in the non-isothermal melt-blown process

The motion characteristic of the polymer jet in a non-isothermal airflow field during melt blowing plays a crucial role in the process of fiber formation and has always been difficult to measure in situ. Many numerical models have been established to simulate the motion of the polymer jet during melt blowing. However, the complex interplay between the airflow field and the polymer jet in these models was usually missed. Here, a coupled air–polymer two-phase flow model in the non-isothermal airflow field was developed by the level-set method, and the temperature dependence of viscosity and density for the polymer jet were also taken into account in our model. Based on the model, the motion of the polymer jet in the melt-blowing process was simulated considering the coupled effect between the air and the polymer jet. The velocities of the polymer jet along x-direction ([Formula: see text]) and y-direction ([Formula: see text]), the whipping amplitude of the polymer jet motion, and the final diameter were discussed and verified. In addition, the effects of critical parameters, such as the inlet airflow velocity, inlet polymer flow velocity, inlet air temperature, and polymer viscosity, on the motion characteristics and temperature of the polymer jet were analyzed numerically.

Formation Mechanism of Fibrous Web in the Solution Blowing Process.

Solution blowing (SB) is a widely reported technology that can be used to fabricate fibers at the micro- and nanoscale. To reveal the fibrous web formation mechanism in SB, we improved our previous melt blowing (MB) model to predict fibrous web structures. Then, we fabricated two samples and simulated the same number of virtual samples in the computer to verify the model. Thereafter, we measured the structural parameters including the fiber diameter, fiber orientation, basis weight, and pore size. Our model provides a good prediction of the fiber orientation and basis weight. However, the predicted fiber diameter was slightly smaller than the measured diameter. The experimental pore size distribution was also different from that in the simulated results. The model provides a virtual fabrication process to reveal a fibrous web formation mechanism and finds a similar distribution of these structural parameters between SB and MB.

Enhancement of fiber attenuation and filtration quality via electrostatic-induction-assisted melt blowing

Melt-blown nonwovens with smaller fiber diameters and fewer roping defects are good candidates for air filtration. However, there have been few publications of experimental work reducing the fiber diameter and improving the roping defects of melt-blown nonwovens at the same time. Here, we reported an electrostatic-induction-assisted melt-blowing (EIMB) process by introducing an induced electrostatic field to the conventional MB process. The EIMB process is based on a commercial process without interfering or charging the polymer jet before spinning. Therefore, the production efficiency of the EIMB process is the same as the conventional MB process. The numerical simulation method was employed to investigate the effects of the electrode width on the melt-blown airflow field since the electrode width is a critical parameter that affects the stability of the MB airflow field. Benefiting from the introduction of the electrostatic field, melt-blown nonwovens with smaller fiber diameters and fewer roping defects were obtained using the EIMB technology. Compared to the conventional MB process, the EIMB process dramatically improved the filtration performance and reduced the energy consumption.