Comparison of Electrostatic Charging at Different Locations in the Melt Blowing Process

Tsai, Ping-Huei; Qin, Guo-wei; Hassenboehler, Charles B.

doi:10.1177/1558925000os-900304

Cited by 5 publications

(4 citation statements)

References 2 publications

(2 reference statements)

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“…The formation of electrets in fibrous filter media creates the ability to significantly enhance filtration efficiency without increasing the pressure drop. The application of charge via corona treatment creates electrets within the fabric that greatly enhance the filtration efficiency. − The charge storage capacity of electret is related to charge traps that prohibit or restrain charge drift through surface and/or bulk. − In PP, the charge traps occur at crystalline boundaries; nucleating agents that increase the number of spherulites and crystalline boundaries will increase the charge storage capacity . About 0.5 wt % stearate added to PP was melt-blown and shown to improve the filtration efficiency initially, the stability over time, and at elevated temperatures (over 70 °C, up to 110 °C) .…”

Section: Introductionmentioning

confidence: 99%

Polymer, Additives, and Processing Effects on N95 Filter Performance

Larsen

Cheng

Daemen

et al. 2021

ACS Appl. Polym. Mater.

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The current severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) pandemic has highlighted the need for personal protective equipment, specifically filtering facepiece respirators like N95 masks. While it is common knowledge that polypropylene (PP) is the industry standard material for filtration media, trial and error is often required to identify suitable commercial precursors for filtration media production. This work aims to identify differences between several commercial grades of PP and demonstrate the development of N95 filtration media with the intent that the industry partners can pivot and help address N95 shortages. Three commercial grades of high melt flow index PP were melt blown at Oak Ridge National Laboratory and broadly characterized by several methods including differential scanning calorimetry (DSC), X-ray diffraction (XRD), and neutron scattering. Despite the apparent similarities (high melt flow and isotacticity) between PP feedstocks, the application of corona charging and charge enhancing additives improve each material to widely varying degrees. From the analysis performed here, the most differentiating factor appears to be related to crystallization of the polymer and the resulting electret formation. Materials with higher crystallization onset temperatures, slower crystallization rates, and larger number of crystallites form a stronger electret and are more effective at filtration.

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Section: Introductionmentioning

confidence: 99%

Polymer, Additives, and Processing Effects on N95 Filter Performance

Larsen

Cheng

Daemen

et al. 2021

ACS Appl. Polym. Mater.

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“…As the polluted particles in the air contains negative electricity, positive electricity charging method was used to treat the polypropylene melt-blown fabric in this paper. The higher charging voltage and smaller charging distance could induce a larger charging current and shorter charging time for the fabric at fixed static electricity capacity [9]. The results suggested that the charging voltage would vary for different equipment where the distance from the charge wire to the fabric might be different.…”

Section: Electret Charge Parametersmentioning

confidence: 97%

Optimization of Processing Parameters for Particle Filtration Efficiency of Polypropylene Melt-blown Fabric

Jiang

Zeng

et al. 2021

Fibers Polym

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Polypropylene melt-blown fabric as the core filter materials plays an important role in manufacturing civil and medical epidemic prevention products. The aim of this study was to optimize and control the particle filtration efficiency and apparent surface quality of the melt-blown fabric from the perspectives of electret masterbatch composition and processing parameters. Magnesium stearate and fumed silica were used as the electret to manufacture polypropylene melt-blown fabric. The layout and charge voltage of the electret device was taken as the variables to optimize and improve the particle filtration efficiency and bulkiness coefficient of the fabric. The temperature of the barrel and die was controlled to enhance the surface quality and corresponding particle filtration efficiency. The results showed that a combination of organic magnesium stearate and inorganic fumed silica could obtain a balance between particle filtration efficiency and smooth processing without being jammed. Increasing the charge voltage and rearranging the position of the charge wires could significantly enhance the particle filtration efficiency. A better particle filtration efficiency and reasonable bulkiness coefficient could be obtained by controlling the diameter of the filaments by regulating the temperature of the barrel and die as well as the suction intensity. The results obtained from this study can offer valuable references in optimization of electret master batch formulation and processing parameters for melt-blown fabric production with different resin.

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“…Over time, the surface charges can move into the bulk and be trapped at depths of several micrometers, which is dependent on the material properties. Other electrode configurations 88 were also invented to be used at different stages 89 of the meltblown process. For example, a patent by Moosmayer et al 90 applied corona discharge directly on the molten fibers before the web formation by putting two biased wire electrodes at the exit of a grounded slot die ( Figure 6B).…”

Section: Corona Dischargementioning

confidence: 99%

Air-Filtering Masks for Respiratory Protection from PM2.5 and Pandemic Pathogens

Xiao

Zhang

et al. 2020

One Earth

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Air-filtering masks, also known as respirators, protect wearers from inhaling fine particulate matter (PM 2.5) in polluted air, as well as airborne pathogens during a pandemic, such as the ongoing COVID-19 pandemic. Fibrous medium, used as the filtration layer, is the most essential component of an air-filtering mask. This article presents an overview of the development of fibrous media for air filtration. We first synthesize the literature on several key factors that affect the filtration performance of fibrous media. We then concentrate on two major techniques for fabricating fibrous media, namely, meltblown and electrospinning. In addition, we underscore the importance of electret filters by reviewing various methods for imparting electrostatic charge on fibrous media. Finally, this article concludes with a perspective on the emerging research opportunities amid the COVID-19 crisis.

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Comparison of Electrostatic Charging at Different Locations in the Melt Blowing Process

Cited by 5 publications

References 2 publications

Polymer, Additives, and Processing Effects on N95 Filter Performance

Polymer, Additives, and Processing Effects on N95 Filter Performance

Optimization of Processing Parameters for Particle Filtration Efficiency of Polypropylene Melt-blown Fabric

Air-Filtering Masks for Respiratory Protection from PM2.5 and Pandemic Pathogens

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