Query: Meltblown quality

title: Computational Fluid Dynamics Simulations and Experiments of Meltblown Fibrous Media: New Die Designs to Enhance Fiber Attenuation and Filtration Quality
abstract: The meltblowing process employs high speed hot air jets to attenuate polymer streams injected from a die head. In this study, we examine design strategies to control the air flow field below the polymer injection point to achieve higher fiber attenuation and meltblown webs with smaller fiber diameters. Computational fluid dynamics (CFD) simulations for new die configurations show that vertical or inclined air constrictors around the primary air jets keep the centerline air velocity and temperature at their maximum values for 10 15 mm longer below the die face than the reference die. Polymer streams are kept near their melting temperatures at higher air velocities for a longer period, resulting in higher fiber attenuation. The underlying mechanisms leading to such behavior are discussed. Experimental results show reduction in fiber diameter and pore size, validating the simulation. Improved filtration properties are also obtained from the nonwovens webs.

title: Meltblown nanofiber media for enhanced quality factor
abstract: Nanofibers definitely hold great advantage and promise in filtration as they have very high specific surface area, which ensures greater probability of capturing the particles and hence, the filtration efficiency of the nanofiber filter media is high. Electrospun nanofibers are prohibitively expensive due to extremely low production rate. With recent advances in melt blowing technology, nanofibers could be produced at production rate few orders of magnitude higher than that of conventional single syringe electrospinning and hence, quite cost effective. Influence of air pressure and die to collector distance (DCD) were studied on the number average fiber diameter for the nanofibers as well as the performance properties of the nonwoven webs, each factor at three discrete levels. The nanofibers were as fine as 260 nm. A very encouraging observation of the study is very high values of quality factor observed for nanofiber nonwoven filter media. In order to compare the filtration efficiency of different nanofiber nonwoven media samples with different basis weight, a novel term of specific filtration efficiency is proposed and was found that the specific filtration efficiency with the increase in DCD or air pressure.

title: Quality variables of meltblown submicron filter materials
abstract: Meltblown submicron fibre filter media has been produced at a production rate of a few orders of magnitude higher than that of conventional single syringe electrospinning. Fibres are produced while varying the air pressure and die to collector distance (DCD) The submicron fibres are about 240 nm in diameter. The average fibre diameter of the submicron fibre nonwoven filters media decreases with increasing DCD and air pressure. The average fibre diameter of each sample is indirectly related to the hydrohead and filtration efficiency, but is directly related to the pore size. The quality factors improve slightly for samples produced at a greater DCD, whereas the quality factors for the media decrease slightly for samples produced at a higher air pressure. The average fibre diameter is related to the hydrohead, filtration efficiency, and pore size. The sample MSFM6 is found to have the smallest average fibre diameter and the highest filtration efficiency. The filtration efficiency of different submicron fibre nonwoven media samples improve with increasing DCD or air pressure. The use of nanofibrous media has proved to be a good way to filter out submicron sized particles.

title: Coalescence efficiency of surface modified PBT meltblown nonwovens in the separation of water from diesel fuel containing surfactants
abstract: Removal of water from diesel fuel is essential to ensure efficient operation of High Pressure Common Rail (HPCR) fuel injection systems used in modern diesel engines. The presence of surfactants in modern fuels (including biofuels) can create conditions in which the interfacial tension between water and fuel is reduced, leading to coalescing media being "disarmed" and less effective in separation. To elucidate this phenomenon in industrially available depth coalescing media, the coalescence efficiency of surface modified poly (butylene terephthalate) (PBT) meltblown nonwoven fabrics possessing a wide range of wetting behaviours was studied. Tuning of the wettability was accomplished by alkaline hydrolysis of the medium. Using reference grade diesel fuel with and without added surfactants, the coalescence efficiency and quality factor were studied by means of a purpose built coalescence test rig. The coalescence efficiency was found to depend on both the fuel composition and the wettability of the treated PBT and the optimum efficiency for each test fuel required a difference in wettability of the PBT. For reference grade diesel, increasing the wettability to 'intermediate' level improved coalescence efficiency, but the quality factor can be negatively affected by water droplet retention within the medium. The reduced quality factor associated with hydrophilic media was even more pronounced in fuels containing surfactants due to increased pressure drop and re emulsification of the fuel in water. These findings highlight the practical challenges that exist in engineering a "universal" coalescing medium suitable for removing water from diesel fuels containing surfactants, based solely on the modulation of fibre wettability and hydrophilicity.

title: One Step Bark Like Imitated Polypropylene (PP)/Polycarbonate (PC) Nanofibrous Meltblown Membrane for Efficient Particulate Matter Removal
abstract: A bark like imitated polypr opylene (PP)/polycarbonate (PC) nanofibrous membrane was constructed by one step meltblown technique for efficient particulate matter (PM) removal. The effects of PC content (0% 1% 3% 5% and 7% on membrane thermal stability, microscopic characteristics, filtration performance, hydrophilicity, and water vapor transmission were investigated. The results demonstrated that using facile design of incompatibility and viscosity difference between PC and PP polymers decreases average fiber diameter, creating a bark like groove appearance and increasing surface potential, making a new PP/PC membrane with high filtration performance. The resultant PP/PC membrane had finer average fiber diameter of 0.63 mm, which was nearly 89.41% lower than PP membranes (5.95 mm) and its quality factor (0.036 Pa 1) was nearly 2.12 times than that of PP membranes (0.017 Pa 1) with the die hole diameter of 0.5 mm. This fabrication technique of a special meltblown filter membrane saves the cost of die retrofitting and post processing, which provides an innovative method for particulate efficient removal of high efficient filters.

title: Zeolitic Imidazolate Framework 8/Polypropylene Polycarbonate Bark Like Meltblown Fibrous Membranes by Facile In Situ Growth Method for Efficient PM2.5 Capture.
abstract: Environmental pollution problems, especially air pollution, seriously endanger public health globally. Facing the severe air pollution, air filters still have many challenges, especially in terms of filtration performance and filtration stability. Herein, a zeolitic imidazolate framework 8/polypropylene polycarbonate bark like meltblown fibrous membrane (PPC/ZIF 8) was designed through meltblown and in situ growth method, achieved efficient PM2.5 capture and great filtration stability under harsh environment. After in situ growth, the PPC/ZIF 8 membrane can dramatically enhance the PM2.5 filtration efficiency without increasing the pressure drop, the PM2.5 filtration efficiency and quality factor up to 32.83 and 116.86 higher than pure PPC membrane, respectively. Moreover, through five filtration wash dry cycles, the PM2.5 filtration performance is still at a high level. This PPC/ZIF 8 membrane provides a new strategy for the preparation of air filter with excellent comprehensive filtration performance.

title: Fabrication and Characterization of Meltblown Poly(vinylidenedifluoride) Membranes
abstract: The meltblowing process may be employed to produce high volume of nonwoven poly(vinylidene difluoride) (PVDF) mats with fine fibers that lead to small pores. Although significant research has been reported on electrospinning of PVDF, there are no studies reported on the formation and characterization of PVDF meltblown mats because of the technological barriers associated with meltblowing the polymer. We investigated the fundamental properties and characteristics of experimental grade melt blowable PVDF (Kynar resin RC 10,287, Arkema, Inc. with the objective of elucidating the structure property process relationships of the meltblown mats. We have produced high quality meltblown PVDF mats with a low solid volume fraction (as low as 22% and an average fiber diameter varying from 2 to 6 mm. The electrochemical resistance and absorbance capacity (electrolyte uptake up to 200% of meltblown PVDF make it suitable for battery separator applications. We show that interactions of the meltblown PVDF with the electrolyte lead to a morphology change in the fibers and a 3% decrease in crystallinity. Using cutting edge meltblowing technologies, meltblown PVDF could become the separator in next generation Li ion batteries.

title: Fabrication of nanofiber meltblown membranes and their filtration properties
abstract: Meltblowing is a unique one step process for producing self bonded fibrous nonwoven membranes directly from polymer resins, with average fiber diameter ranging between 1 and 2 mm. Determining routes for making nano or submicron fibers using this process are desirable since there are many manufacturing assets that are already in place. It is envisaged that these nonwoven membranes will find applications in critical areas such as medical, hygiene, filtration, bioseparation, and others. In this study, we investigate the influence of different die configurations and operating conditions on fiber and web characteristics. We also report on strategies for reducing the fiber size below one micron to achieve higher filtration quality at lower basis weight relative to the conventional meltblown webs. Their performance is compared to a control meltblown sample produced by using a typical die design. We find that production of nano meltblown membranes with an average fiber size in the range of 300 500 nm using this new die design is possible and report on process operating conditions that result in such structures. These samples achieve equal filtration efficiencies to that of our control sample at 88% reduced basis weight but at a lower polymer throughput. The lower basis weight also resulted in a lower pressure drop and overall, the new samples exhibited a higher quality factor, twice that of the control. These results show significant promise for the use of nano meltblown fibers in filtration applications.

title: Overview and Analysis of the Meltblown Process and Parameters
abstract: This paper is a comprehensive review of the meltblown process and parameters. The meltblown process is complex because of the many parameters and interrelationships between those parameters. Due to the competitiveness of the industry, process settings and polymers used are secretive, but there are several key researchers that have published studies on the interactions of meltblown variables. A majority of the research conducted has been on the relationship of process parameters and mean fiber diameter in order to understand how to produce smaller and higher quality fibers. This paper offers suggestions for future research on specific meltblown parameters.

title: Current Status of Meltblown Technology and its Innovation in the Process of Research Development
abstract: This article briefly states the gap of meltblown technology of China with abroad in terms of products quality,technology innovation,manufacturing cost structure and RD.In addition,the approach of sustainable development of spunbond and meltblown technology in China is discussed based on the above statement.