Journal of Applied Polymer Science: Production and characterization of hybrid BEH-PPV/PEO conjugated polymer nanofibers by forcespinning®
The fabrication of hybrid poly(2,5-bis(2′-ethyl-hexyl)-1,4-phenylenevinylene) (BEH-PPV) and polyethylene oxide (PEO) nanofibers is reported. Nanofibers were created using a novel production method that uses centrifugal rather than electrostatic force to produce nanofibers. The nanofiber production method exhibits high yield production of nanofibers enabling mass-production capabilities. Thermo-physical characterization and X-ray diffraction of bulk PEO and BEH-PPV was conducted, and the results are compared with the produced hybrid nanofibers.
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Functional Materials Letters: Large-scale Synthesis of Tin-doped Indium Oxide Nanofibers Using Water as Solvent
Here we report the successful fabrication of tin-doped indium oxide (ITO) nanofibers using a scalable Forcespinning® method. In this environmentally-friendly process, water was used as the only solvent for both Polyvinylpyrrolidone (PVP, the sacrificial polymer) and the metal chloride precursor salts. The obtained precursor nanofiber mats were calcinated at temperatures ranging from 500–800°C to produce ITO nanofibers with diameters as small as 400 nm. The developed ITO nanofibers were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction analysis.
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Polymer Engineering and Science: Preparation and characterization of polyvinylidene fluoride nanofibrous membranes by forcespinning®
Nanofibers of polyvinylidene fluoride (PVDF) were prepared using solutions of PVDF with acetone and dimethylacetamide. The solutions were prepared at different concentrations (18, 21.5, and 25% wt) of PVDF. The nanofiber membranes were produced by using the Forcespinning™ method. Parameters such as the orifice size and spinneret angular velocity were varied. The produced membranes were characterized using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction to determine the effect of varying parameters in the Forcespinning™ process on fiber diameter, bead formation, thermal stability, polymorphism, and morphology of the fibers and overall structure of the membrane. It was observed that polymer concentration played a key role in fiber and bead formation; at higher concentrations (such as 25 wt%), the fiber diameter increased but the bead formation decreased. The prepared composite membranes have potential applications on separators for Li-ion batteries, ultra filtration membranes, and proton conductivity membranes for fuel cells applications.
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ACS Macro Letters: Solventless High Throughput Manufacturing of Poly(butylene terephthalate) Nanofibers
Nanofibers possess high surface area to volume ratios and are particularly attractive for a variety of applications including tissue regeneration, drug delivery, fiber-reinforced composites, filtration, and protective clothing. Though the production of nanofibers from common thermoplastic polymers is relatively well-demonstrated, processing constraints have limited high throughput manufacturing of nanofibers from high performance polymers. This has in turn limited broad technological exploitation of polymer nanofibers in areas such as hot chemical filtration or high-performance lightweight composites for aerospace and defense applications. We report here that nanofibers can be produced in a solventless high throughput process from polymers such as poly(butylene terephthalate) (PBT) using a newly developed technology termed “Forcespinning” that employs centrifugal force to attenuate fibers. Our investigations also show that these nanofibers have a high crystallinity and enhanced molecular orientation which is important for realizing desirable physical and chemical properties of many high-performance polymer fibers.
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TAPPI: “Forcespinning™: An important advancement in Nanofibers Production”
The processing of polymers into nanofibers offers a broad range of applications in areas such as filtration, catalysis, tissue engineering, photonics and sensors. The centrifugal nanofiber processing called ForcespinningTM allows for fabrication of nanofibers both from polymer solutions and melts [1-4]. Polymers such as Polypropylene are melt processed without using solvents. The polymers are melted by applying radiant heat onto the spinneret cup with orifices that holds the polymer until it is spun into nanofibers using centrifugal force. The fine control over morphology and fiber diameter in melt forcespinning is achieved by controlling the operating parameters such as: rotational speed of the spinneret, orifice size, temperature of the spinneret, and collection system. Solution spinning adds the operating parameters of solution concentration and solvents. This paper discusses forcespinning system focusing on development and characterization of nanofibers through solution spun Nylon 6, Polyvinylidene Fluoride (PVDF) and melt spun Polypropylene (PP). These polymers were selected for this study given their favorable properties for filtration applications.
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Journal of Applied Polymer Science: Production and characterization of polycaprolactone nanofibers via forcespinning™ technology
Among the myriad of methods for polymer nanofiber production, there are only a few methods that can produce submicron range fibers in bulk from melt or solution samples. The Forcespinning™ method allows a substantial increase in sample yield while simultaneously maintaining the integrity of uniform fibers in the nanometer range. The high production yield of such a method greatly reduces the time needed to produce bulk quantities of fibers which may be critical in many fields of research and industry, in particularly in fields relating to biopolymers. The aim of this study was to use this method to form nonwoven mats of polycaprolactone (PCL) nanofibers and to quantitatively analyze the production and characterization of the produced fibers. The bulk PCL was dissolved in dichloromethane and the solutions were forcespun at varying speeds ranging from 3000 to 9000 rpm. It was observed that fiber diameter decreased with increasing rotational speed. The average fiber diameter at 9000 rpm was 220 nm with a standard deviation of ±98 nm. The morphology and degree of crystallinity were characterized by scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction.
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Materials Today – Electrospinning to Forcespinning
Electrospinning to Forcespinning™
04 November 2010
Kamal Sarkar, Carlos Gomez, Steve Zambrano, Michael Ramirez, Eugenio de Hoyos, Horacio Vasquez and Karen Lozano
In 1902, Morton and Cooley discovered the electrospinning process, the way it is known now and filed US patents. Formhals then investigated the problem for about a decade and obtained nine US patents on different aspects of electrospinning. These patents identified a number of key issues and their potential solutions to optimize their goal of manufacturing “fine fibers”. Unfortunately, due to technology limitations, they did not realize the making of nanofibers nor their significant application potentials.
In 1995, Doshi and Reneker re-introduced the electrospinning process, by then scanning electron microscope (SEM) was commonly available and they rightly place the significance of nanofibers in perspective. They clearly identified a myriad of applications for the electrospun nanofibers in as diverse fields as structures, textile, membrane, and biomedical engineering. When Doshi and Reneker re-introduced the century old process “electrical spinning”, they also coined the more convenient term “electrospinning”.
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