Melt Blowing Research Articles

Facile fabrication of polylactic acid/polyethylene glycol micro-nano fabrics with aligned fibrous roughness for enhancing liquid anisotropic wetting performance via double-stage drafting melt blowing process

The liquid anisotropic wetting properties have garnered considerable interest due to the rapidly rising usage of functional micro-nano fabrics in sanitary product applications. However, designing and preparing such materials in a manner that is easy, safe, and vast in a large scale remains a problematic issue. In this work, a poly (lactic acid) / poly (ethylene glycol) (PLA/PEG) micro-nano fabric with aligned fibrous roughness inspired by bamboo leaves was designed and prepared via a simple double-stage drafting melt blowing process. The results indicate that aligned fibrous roughness and homogenized fiber diameters ranging from 4.4 to 2.7 µm were successfully tailed by adjusting the drafting ratios from 1.0 to 3.0. Additionally, benefiting from the aligned fibrous roughness, the PLA/PEG micro-nano fabric demonstrated excellent anisotropic wetting performance, evidenced by a clear contrast between parallel static water contact angles (θ//) and perpendicular (θ⊥) to the longitudinal direction, as well as remarkable contact angle hysteresis. Additionally, the samples had a significant aspect ratio of 3.16. As a result, this PLA/PEG micro-nano fabric may be an alternative for medical and health applications such as medical dressings and meshes.

Melt-blown fiber mat interleaving enhances the performance of single-polypropylene composites

In this study, we demonstrate that integrating melt-blown fiber mat interleaves into single-polypropylene composites enhances several mechanical properties and influences the morphology positively. Polypropylene veils were generated by melt blowing. We then created single-polypropylene composites by film-stacking in which we applied a film as a matrix, a woven fabric as primary reinforcement, and the melt-blown fiber mats as interleaves. The tensile modulus was improved in the range of 20%–46%, and the interlaminar shear strength and the perforation energy at impact were increased by 17% and 14%, respectively, due to interleaving. Master curves were constructed from dynamic mechanical analysis frequency sweep tests based on the time–temperature superposition principle. The storage modulus significantly increased while the tanδ decreased. The interleaving considerably reduced the delamination by creating a net-like structure leading to superior interfacial adhesion. The interleaving demonstrated in this study can promote single-polymer composites’ utilization in various engineering applications where high toughness and impact resistance are required.

Impact of Wearing on Filtration Performance of Electrostatic Filter Face Masks.

Certified disposable respirators afford important protection from hazardous aerosols but lose performance as they are worn. This study examines the effect of wear time on filtration efficiency. Disposable respirators were worn by CSIRO staff over a period of 4 weeks in early 2020. Participants wore the respirator masks for given times up to eight hours whilst working in laboratory/office environments. At that time COVID-19 precautions required staff to wear surgical (or other) masks and increase use of hand sanitizer from dispenser stations. Results obtained from a test group of ten individuals without health preconditions show an increasing number of masks failing with wear time, while the remainder continue to perform nearly unaffected for up to 8 h. Some masks were found to retain filtration performance better than others, possibly due to the type of challenge they were subjected to by the wearer. However, the rate and extent of decay are expected to differ between environments since there are many contributing factors and properties of the aerosol challenge cannot be controlled in a live trial. Penetration and variability increased during wear; the longer the wear time, the more deleterious to particle removal, particularly after approximately 2 h of wear. This behavior is captured in a descriptive statistical model based on results from a trial with this test group. The effectiveness of the masks in preventing the penetration of KCl particles was determined before and after wearing, with the analysis focusing on the most penetrating particles in a size range of 0.3–0.5 µm diameter where respirator masks are most vulnerable. The basic elements of the study, including the approach to filter testing and sample sanitization, are broadly applicable. Conclusions also have applicability to typical commercially available single-use respirator masks manufactured from melt blown polypropylene as they are reliant on the same physical principles for particle capture and electrostatic enhancement was comparable for the particle size range used for detection.

Investigation The Bacterial Filtration Efficiency Of Medical Masks From Polyethylene Terephthalate (PET) Fabric

The Covid-19 pandemic period caused attention to the importance of medical masks. Various studies show that mask fabrics should not be ordinary. Uncontrollably produced masks with poor quality have become an important problem in the market. Based on the idea that viruses spread by binding themselves to environmental bacteria and water droplets, it is assumed that the basic filtering efficiency of masks is of primary importance and requires the use of masks with a certain filtering ability. The purpose of the present study was to produce fabric masks from Polyethylene Terephthalate (PET), and to investigate the filtration efficiency. Masks were produced from the developed PET fabric and widely used Meltblown (MB) fabric, which is known to have a high filtration rate and their filtration efficiencies were compared. EN 14683 BFE methods was used in laboratory setting to measure the filtration efficiency of the masks. It was found that the MB/3-layer mask had 99.7% (SD±0.2) capacity of filtering microorganisms and the 3-layer ART/Mask in the developed PET structure was capable of filtering microorganisms at a rate of 96.8% (SD±2.7). When the filtration efficiency of the masks detected for each microorganism was compared separately, no statistically significant differences were detected (p>0.05). The tested mask was found to have a similar high microbial filtration rate to the mask made of meltblown fabric. This suggests that it will reduce the spread of viruses by attaching themselves to bacteria from sick individuals. It is also it can has protective effect for nosocomial infections.

Overview of the Fiber Dynamics during Melt Blowing

Melt blowing (MB) is an industrial process used in producing microfibrous nonwoven materials. Over the past decades, a considerable amount of theoretical and experimental research has been conducted on the mechanisms of fiber dynamics during MB. Although some studies have been summarized by recently published review articles, the evolution of the theoretical equations and improvements in the experiments are rarely mentioned. Therefore, this work presents a comprehensive overview of the research on fiber dynamics, especially on the evolution of its theories. For the theoretical aspect, the evolution of the fiber formation and the fibrous web formation models were analyzed. In addition, online and offline experiments were used to demonstrate fiber formation and fibrous web mechanisms. The fundamental studies reviewed in this paper contributed noteworthy findings in controlling the fiber and web quality, thereby improving the product behavior during MB.

Advances in Melt Blowing Process Simulations

Advances in Melt Blowing Process Simulations

Improvement of Polytetrafluoroethylene Membrane High-Efficiency Particulate Air Filter Performance with Melt-Blown Media.

Polytetrafluoroethylene (PTFE) membrane filters are widely used in low-load application areas, such as industrial cleanrooms, due to their low initial pressure drop. In this study, melt-blown (MB) nonwoven was introduced as a pre-filtration layer at the front end of a high-efficiency particulate air (HEPA) filter to improve the filter performance of the PTFE membrane. Pre-filtration reduces the average particle size, which reaches the PTFE membrane and reduces the dust load on the HEPA filters. A comparative analysis of the HEPA filters by composite MB and PTFE was conducted. Regarding the MB composite on the PTFE, low-weight and high-weight MB composites were effective in increasing dust filtration efficiency, and the dust loading capacity of the PTFE composite with high-weight MB increased by approximately three times that of the PTFE membrane. In addition, the filter was installed on an external air conditioner in an actual use environment and showed a high efficiency of 99.984% without a change in differential pressure after 120 days.

Airflow, Fiber Dynamic Whipping, and Final Fiber Diameter in Flush Sharp-Die Melt Blowing with Different Air-Slot Widths

Melt streams were attenuated into microfibers by high-speed airflow during melt blowing. The present work explored the effect of air-slot width on the fiber diameter and diameter evenness in flush sharp-die melt blowing. The airflow in different die melt blowing was first numerically simulated by the CFD approach. Then, the fiber dynamic whipping was captured by high-speed photography. Finally, a spinning experiment was implemented and the fiber diameters were measured. The result reveals that the sharp die with a larger air-slot width produces fibers with a larger diameter, but the uniformity is obviously better. This study reveals that the air flow, fiber whipping, and final fiber diameter are closely related to each other. The quality control of melt-blown fiber can be carried out by controlling the fiber whipping motion.

Polymer-Based Electrophoretic Deposition of Nonwovens for Medical Applications: The Effect of Carrier Structure, Solution, and Process Parameters.

Hyaluronate and alginate are non-toxic and biocompatible polymers, which can be used for surface modification and functionalization of many kinds of materials. Electrophoretic deposition (EPD) has several advantages, including its versatility, simplicity, and ability to coat substrates with complex shapes, and is used for the creation of antimicrobial or hydrophobic coatings on metallic biomaterials, among other applications. However, its utilization for applying biopolymer layers on textiles is very limited due to the more complex structure and spatial characteristics of fibrous materials. The aim of this research was to analyze the effects of selected EPD process parameters and the structural characteristics of fibrous carriers on the kinetics of the process and the microscopic characteristics of the deposited layers. The influence of solution characteristics, process parameters, and carrier structures obtained using two different techniques (melt blown and spun-bonded) were analyzed. The morphology and structure of the created deposits were analyzed using scanning electron microscopy and computed tomography, and molecular structure analysis was performed with Fourier Transform Infrared spectroscopy. The surface mass and thickness of fibrous poly (lactic acid)-based carriers were analyzed in accordance with the respective standards. This study serves as a basis for discussion and further development of this method with regard to fibrous materials for medical applications.

Porous Fibers Templated by Melt Blowing Cocontinuous Immiscible Polymer Blends.

We report a scalable melt blowing method for producing porous nonwoven fibers from model cocontinuous polystyrene/high-density polyethylene polymer blends. While conventional melt compounding of cocontinuous blends typically produces domain sizes ∼1-10 μm, melt blowing these blends into fibers reduces those dimensions up to 35-fold and generates an interpenetrating domain structure. Inclusion of ≤1 wt % of a block copolymer compatibilizer in these blends crucially enables access to smaller domain sizes in the fibers by minimizing thermodynamically-driven blend coarsening inherent to cocontinuous blends. Selective solvent extraction of the sacrificial polymer phase yielded a network of porous channels within the fibers. Fiber surfaces also exhibited pores that percolate into the fiber interior, signifying the continuous and interconnected nature of the final structure. Pore sizes as small as ∼100 nm were obtained, suggesting potential applications of these porous nonwovens that rely on their high surface areas, including various filtration modules.

Effect of Introducing Long Chain Branching on Fiber Diameter and Fiber Diameter Distribution in Melt Blowing Process of Polypropylene

Abstract In the melt blowing process, the molten polymers extruded from nozzles are elongated by high-velocity and high-temperature air flow. In this study, with the aim of stabilizing the melt blowing process for producing nonwoven webs with fine diameter fibers, the effect of the control of polymer rheology by the introduction of either low melt flow rate (MFR) polypropylene (PP) or long chain branched PP (LCB-PP) to regular high MFR PP was investigated. Introduction of low MFR PP into regular PP increased shear viscosity and fibers of larger diameter were produced in the melt blowing process, while introduction of low MFR LCB-PP suppressed the elongational viscosity reduction with the increase of strain rate, and eventually spinning was stabilized. It was found that the blending of an optimum amount of LCB-PP to regular PP caused the stabilization of the melt blowing process. As a result, the formation of nonwoven webs consisting of fine fibers of rather uniform diameter distribution could be achieved.

Solution Blow Spinning (SBS): A Promising Spinning System for Submicron/Nanofibre Production

Submicron/nanofibres possess great potential for application in different areas because of their amazingly high surface area-to-weight ratio. The demand for fabrication of such fibres on a huge scale is increasing with the fast improvement of nanotechnology. Traditionally, nanofibre fabrication methods have intrinsic faults, limiting their application in industry. Solution blow spinning (SBS) is a viable option for producing adaptable and conformable submicron/nanofibre mats on a variety of surfaces. The technique can be employed to produce submicron/ nanofibres with only a simple commercial airbrush, a concentrated polymer solution, and a compressed gas source. It depends on the high velocity of decompressed air that allows the rapid stretching and evaporation of the solvent from a polymeric solution jet at the outlet of the concentric nozzles system. Along with recent advancements, the importance and drawbacks of the solution blow spinning system in comparison to other methods, such as electrospinning and melt blowing, are briefly discussed. Furthermore, the mechanisms of co-axial SBS spinning and micro SBS spinning system for submicron/nanofibre fabrication are also described. Drawbacks and research challenges of SBS are also addressed in this paper.

Comparison of melt-blown and glass-fiber HEPA asbestos filters based on ISO filter classes, filtration efficiency, power consumption, and face velocity

ABSTRACT The purpose of this study was to determine the most efficient airborne asbestos filter for use in an HEPA negative air machines through filter performance testing. The filter classes applied conformed with ISO and European standard (EN 1822) regarding fractional efficiency by dust loading amount for filters, fractional efficiency for negative air machines, and consumption of electrical power at filter size 0.3 μm. Class H13 had the highest fractional efficiency among the three experimental filter classes by particle size, at face velocity of (1, 2, and 3) m/s. Melt-blown (MB) filters exhibited higher fractional performance than did glass-fiber filters at all particle sizes tested (0.3, 0.5, and 1.0 µm). The power consumption of glass-fiber filters was higher (at 10 m3/min) than that of melt-blown filters. Therefore, melt blown filters would be more cost-effective than glass fiber filters for use in HEPA negative air machines, for protection against airborne asbestos. Implications: Air cleaner and related systems were developed to control a variety of airborne pollutants in general indoor environments, but there was no certified system for focusing on asbestos fractional efficiency using filter tests. Class H13 had the highest fractional efficiency among the three experimental filter classes by particle size, at face velocity of (1, 2, and 3) m/s. Melt-blown filters exhibited higher fractional performance than did glass-fiber filters at all particle sizes tested (0.3, 0.5, and 1.0 µm). The power consumption of glass-fiber filters was higher (at 10 m3/min) than that of melt-blown filters.

Сорбция и удерживающая способность модифицированных волокнисто-пористых материалов по отношению к нефти и нефтепродуктам

Purpose. Investigation of the effect of electric polarization of polymeric fibrous materials on the sorption of oil and petroleum products. Methods. Melt blowing of Borealis brand polypropylene. Polarization of samples in a corona discharge field of positive and negative polarity with a strength of 25 kV/cm. Sample processing in low-temperature oxygen plasma of a glow discharge with a frequency of 35 kHz. Weighting method for determining sorption characteristics. Scanning electron microscopy method. Electret thermal analysis method. Findings. The dependence of sorption parameters of materials on the type of physical modification – corona discharge of different polarity and low-temperature plasma of a glow discharge – has been established. It is shown that the modification of fibrous-porous materials in a corona discharge field to impart electret properties to them somewhat reduces the sorption characteristics of these materials in relation to oil. In the manufacture of sorption materials for the collection of crude oil, the original unmodified fibrous-porous material should be used. It has been experimentally established that in the manufacture of sorption materials for the collection of light oil fractions, the preferred method is the modification of fibers in a corona discharge field of negative polarity. Electrization has a significant effect on the processes of sorption by fibers of its lipophilic components. A physical model of the sorption of petroleum products by electret samples of polymeric fibrous-porous materials is proposed. Application field of research. Fibrous-porous polymeric materials subjected to physical modification with the formation of an electret state can be used for: sorption of some oil fractions, filtration of liquids from contaminants of a dielectric nature, purification of air from ionized dust containing radioactive particles, targeted separation of biological fluids containing dielectric and (or) electret components.

Single Polymer Composites Made of Melt-blown PP Mats and the Modelling of the Uniaxial Tensile Behaviour by the Fibre Bundle Cells Method

In this study, we generated polypropylene fibre mats via melt blowing (average diameter: 1.03 µm), and then produced self-reinforced composites using hot compaction and investigated the effect of the processing temperature. Scanning electron microscopy (SEM) revealed that our composites had good consolidation, low void content and besides, the fibres and the matrix were clearly distinguishable. The differential scanning calorimetry (DSC) tests showed that the composites are easy to recycle by re-melting. The tensile tests of the melt-blown nonwovens and the produced composites revealed that increasing the temperature of hot compaction results in embrittlement (from ductile to brittle) of the samples, which means higher specific tensile forces and smaller deformations. Using the Fibre Bundle Cells modelling method, we developed a phenomenological, analytical model to describe the total tensile curve (both the deformation and the failure behaviour) and analyse the tensile properties of these hot compacted composites. The determination coefficients (R2) between the modelled and measured force were larger than 0.99 and the relative mean squared error (RMSE) values (related to the measured maximum force value) were smaller than 3 % in every examined case, which indicated good modelling. Hence, the FBC model not only described the tensile behaviour of the nonwovens well, but it was also applicable for the composites.

A review of processing strategies to generate melt-blown nano/microfiber mats for high-efficiency filtration applications

Protective masks – worn properly - have become the key to wither away the COVID-19 pandemic. Nowadays, the vast majority of these masks are made of nonwoven fabrics. High-quality products have mainly melt-blown filtering layers of nano/microfiber. Melt blowing produces very fine synthetic nonwovens from a wide range of polymers and allows a fair control of the fiber structure and morphology that makes it ideal for filtration purposes. Melt blowing has a high throughput, and the low price of the filter makes these products widely available for civil use. Although melt-blown fiber applications were rapidly growing in the last three decades, we still have limited knowledge on the processing parameters. In this regard, we detailed the melt blowing parameters to obtain a filter media with high particle capturing efficiency and a low-pressure drop. We summarized the melt-blown fiber mat characteristics with specific attention to the pore size, the porosity, the fiber diameter, the fiber packing density and the air permeability desired for highly efficient filtration. Even though we cannot estimate the future social effects and the trauma caused by the current pandemic, and protective masks might remain a part of everyday life for a long while. That also implies that near-future investments in wider manufacturing capacities seem inevitable. This paper also aims to facilitate masks' production with improved filtration efficiency by reviewing the recent developments in melt blowing, the related applications, the effects of processing parameters on the structure and performance of the nonwoven products focusing on the filtration efficiency via knowledge.

Daylight-driven rechargeable, antibacterial, filtrating micro/nanofibrous composite membranes with bead-on-string structure for medical protection

• The bead-on-string micro/nanofibrous hierarchical membrane is constructed. • The composite membrane has a fast recharge rate, a strong recharge capacity and storage stability. • The composite membrane has high-efficient filtration against PM 2.5. • The composite membrane possesses a good comfort and higher antibacterial properties under light. • The membrane can be used as daylight-driven rechargeable, bacterial and reusable medical protective materials. Drug-resistant pathogens render tremendous pressure and challenges on the development of biomedical materials with highly efficient barrier and long-lasting antibacterial efficacy. Herein, this study combined metal–organic framework (zeolite imidazolate framework 8 [ZIF-8]) and melt blowing–electrospinning method to construct the bead-on-string structure of PPCL@PDA/TAEG/PCL/ZIF8 hierarchical micro/nanofibrous composite membranes with rechargeable, antibacterial, and high-efficiency filtration properties. The incorporation of bead-on-string structure provides the PPCL@PDA/TAEG/PCL/ZIF8–9 composite membranes with above 99.9% filtration efficiency against ultrafine particles larger than 500 nm in diameter. Moreover, the composite membrane quickly releases reactive oxygen species under daylight conditions. The release amount after charging for 1 h is 13009.41 μg/g for •OH and 405.72 μg/g for H 2 O 2 . The composite membranes retain 89.9% and 65.1% of the original charging capacities of •OH and H 2 O 2 , respectively, after seven cycles. These membranes also show greater antibacterial activity, and the sterilizing rates against S. aureus and E. coli reach 99% and 95%, respectively, in daytime and nighttime. These daylight-driven rechargeable micro/nanofibrous membranes can be used in the development of reusable medical protective materials with highly efficient filtration and daylight-driven rechargeable antibacterial efficacy.

Simulation of polymer jet motion during melt blowing with phase field method

In the past two decades, a number of models have been built to simulate the motion of polymer jet during melt blowing. Unfortunately, the complex interaction between polymer jet and air flow field has been rarely reported. In this work, a phase-field method was applied to simulate the coupling effects between polymer and air flow during melt blowing and the computed results were compared with the results of the model built through level-set method and experimental results. Velocity in the x direction, velocity in the y direction, whipping amplitude and diameter of polymer jet were discussed, respectively. It was found that the velocity predicted by the present model was higher than that predicted by the level-set method. However, both of them are close to the experimental value. The calculated final fiber diameter based on the phase-field method is much closer with the experimental value than that based on the level set method. Based on the model, the effect of polymer surface tension and slot angle on the polymer jet velocity were discussed.

Pyrolysis kinetic behaviour and TG-FTIR-GC–MS analysis of Coronavirus Face Masks

In the times of Covid-19, face masks are considered to be the main source of protection against the virus that reduces its spread. These masks are classified as single-use medical products with a very short service life, estimated at few days, hence millions of contaminated masks are generated daily in the form of hazardous materials, what requires to develop a safe method to dispose of them, especially since some of them are loaded with viruses. 3-ply face masks (3PFM) represent the major fraction of this waste and are composed mainly from polypropylene and melt blown filter with high content of volatile substances (96.6 wt.%), what makes pyrolysis treatment an emerging technology that could be used to dispose of face masks and convert them into energy products. In this context, this work aims to study pyrolysis kinetic behaviour and TG-FTIR-GC–MS analysis of 3PFM. The research started with analysis of 3PFM using elemental analysis, proximate analysis, and compositional analyses. Afterwards, TG-FTIR system was used to study the thermal and chemical decomposition of 3PFM analyzed at different heating rates: 5, 10, 15, 20, 25, and 30 °C/min. The GC/MS system was used to observe the synthesized volatile products at the maximum decomposition temperatures. After that, isoconversional methods, the advanced nonlinear integral isoconversional method, and the iterative linear integral isoconversional method were used to determine the activation energies of mask pyrolysis, while the distributed activation energy model and the independent parallel reactions kinetic model were used to fit TGA and DTG curves with deviations below <1. The TGA-DTG results showed that 3PFM can decompose in three different periods with a total weight loss of 95 % and maximum decomposition in the range 405−510 °C, while the FTIR spectra and GC–MS analysis exhibited that – CH (aromatic and aliphatic) and 2,4-Dimethyl-1-heptene (28–43 % based on heating rate) represented the major compounds in the released volatile components. Finally, Vyazovkin and the iterative linear integral isoconversional methods gave activation energies almost similar to that obtained by the KAS isoconversional method.

Swirling Diffused Air Flow and Its Effect on Helical Fiber Motion in Swirl-Die Melt Blowing

In melt blowing, high-velocity air impinges upon a polymer stream and attenuates it into micro-fibrous materials. The structure of the melt-blown die controls the airflow field and determines the process of fiber formation. This work focused on exploring the air swirling diffusion in a particular swirl-die melt blowing. The air swirling diffusion was analyzed by measuring the lateral velocity (vr), and the lateral twisting velocity (vs) by using single- and dual-wire probe hot-wire anemometer. Results showed that the vr had a diffusion boundary, while the distribution of the vs located out of the diffusion boundary of vr. The fiber paths in the swirl-die melt blowing, which was captured by high-speed camera, showed that the cone angle of the fiber path was consistent with the cone angle of vr-diffusion boundary. However, most of the twisting velocity (vs) located out of the region of fiber path, resulting in that the fiber helical motion was initiated just at a critical z-position, rather than in the region further away from the die. This work shows that energy-wasting of vs exists during swirl-die melt blowing, and a more optimized structure of this kind of die should be found.