TY - RPRT TI - Micro and nanofiber nonwoven spunbonded fabric AU - Pourdeyhimi, B. AU - Fedorova, N.V. AU - Sharp, S.R. DA - 2013/1/8/ PY - 2013/1/8/ M1 - US8349232B2 M3 - Patent SN - US8349232B2 ER - TY - RPRT TI - High strength, durable micro and nano-fiber fabrics produced by fibrillating bicomponent islands in the sea fibers AU - Pourdeyhimi, B. AU - Fedorova, N.V. AU - Sharp, S.R. DA - 2013/4/16/ PY - 2013/4/16/ M1 - US8420556B2 M3 - Patent SN - US8420556B2 ER - TY - CONF TI - Latest Developments in Nonwovens for Filtration, Keynote address AU - Pourdeyhimi, B. T2 - American Filtration Society C2 - 2013/// CY - Minnesota DA - 2013/// PY - 2013/// ER - TY - CONF TI - Nonwovens with Stretch and Recovery AU - Pourdeyhimi, B. T2 - TechTextil C2 - 2013/6// CY - Frankfurt, Germany DA - 2013/6// PY - 2013/6// ER - TY - CONF TI - Osteochondral Tissue Engineering Using Human Adipose Derived Stem Cells AU - Williams, J. AU - Mohiti-Asli, M. AU - Tuin, S.A. AU - Morgan, D. AU - Kannan, A. AU - Hluck, B. AU - Loboa, E.G. T2 - 59th Annual Orthopaedic Research Society Conference C2 - 2013/1// C3 - Proceeding of the 59th Annual Orthopaedic Research Society Conference CY - San Antonio, Texas DA - 2013/1// PY - 2013/1// ER - TY - CONF TI - Novel High Surface Area Poly(L-lactic Acid Nonwoven Scaffolds Exposed to Pulsatile Fluid Flow Increase RUNX2 Expression in Human Adipose Derived Stem Cells AU - Tuin, S.A. AU - Miller, S.M. AU - Ganesh, V. AU - Cunningham, D.J. AU - Pfeiler, W.T. AU - Bernacki, S.H. AU - Pourdeyhimi, B. AU - Loboa, E.G. T2 - Triennial International Engineered Fabrics Conference and Expo C2 - 2013/4// C3 - Proceedings of the triennial International Engineered Fabrics Conference and Expo CY - Miami Beach, Florida DA - 2013/4// PY - 2013/4// ER - TY - CONF TI - Winged Fiber Scaffolds Enhance hASC Proliferation, Osteogenesis, and Mechanosensitivity AU - Tuin, S.A. AU - Miller, S.M. AU - Cunningham, D.J. AU - Pfeiler, W.T. AU - Bernacki, S.H. AU - Pourdeyhimi, B. AU - Loboa, E.G. T2 - Annual Biomedical Engineering Society Conference C2 - 2013/9// C3 - Proceedings of the Annual Biomedical Engineering Society Conference CY - Seattle, WA DA - 2013/9// PY - 2013/9// ER - TY - CONF TI - 3-D Computational Modeling of Fluid Flow Over Winged Fibers: Winged Fibers Enhance Shear Stress and RUNX2 Expression in hASC AU - Tuin, S.A. AU - Cunningham, D.J. AU - Pfeiler, W.T. AU - Bernacki, S.H. AU - Pourdeyhimi, B. AU - Loboa, E.G. T2 - 15th Annual North Carolina Tissue Engineering and Regenerative Medicine Society Conference C2 - 2013/10// C3 - Proceedings of the 15th Annual North Carolina Tissue Engineering and Regenerative Medicine Society Conference CY - Winston-Salem, NC DA - 2013/10// PY - 2013/10// ER - TY - CONF TI - 3-D Computational Modeling of Fluid Flow Over Winged Fibers: Winged Fibers Enhance Shear Stress and RUNX2 Expression in hASC AU - Tuin, S.A. AU - Cunningham, D.J. AU - Pfeiler, W.T. AU - Bernacki, S.H. AU - Pourdeyhimi, B. AU - Loboa, E.G. T2 - Annual Joint Meeting of the Materials Research Society and the Materials Information Society C2 - 2013/11// C3 - Proceedings of the Annual Joint Meeting of the Materials Research Society and the Materials Information Society CY - Raleigh, NC DA - 2013/11// PY - 2013/11// ER - TY - CONF TI - Micro and Macro Modeling Filtration in Nonwovens AU - Pourdeyhimi, B. AU - Tafreshi, H. AU - Maze, B. T2 - Filtrex 2013 C2 - 2013/5// CY - Seoul, Korea DA - 2013/5// PY - 2013/5// ER - TY - RPRT TI - Biodegradable non-woven fabric having plant virus encapsulated actives for drug delivery AU - Pourdeyhimi, B. AU - Lommel, S.A. AU - Honarbakhsh, S. AU - Carbonell, R. AU - Guenther, R.H. DA - 2013/9/17/ PY - 2013/9/17/ M1 - 8535727 M3 - U.S. Patent SN - 8535727 ER - TY - RPRT TI - Lightweight High-Tensile, High-Tear Strength Bicomponent Nonwoven Fabrics AU - Pourdeyhimi, Behnam DA - 2013/11/13/ PY - 2013/11/13/ M1 - 5339896 M3 - Japan Patent SN - 5339896 ER - TY - RPRT TI - Durable Fabrics Produced by Fibrillating Multilobal Fibers AU - Pourdeyhimi, Behnam AU - Sharp, Stephen R. DA - 2013/4/3/ PY - 2013/4/3/ M1 - 2,165,010 M3 - Europe Patent SN - 2,165,010 ER - TY - RPRT TI - High Strength Durable Micro and Nano-Fiber Fabrics Produced by Fibrillating Islands in the Sea Fibers AU - Pourdeyhimi, Behnam DA - 2013/7/2/ PY - 2013/7/2/ M1 - 10-1280398 M3 - Korea Patent SN - 10-1280398 ER - TY - RPRT TI - High Strength Durable Micro and Nano-Fiber Fabrics Produced by Fibrillating Islands in the Sea Fibers AU - Pourdeyhimi, Behnam DA - 2013/8/21/ PY - 2013/8/21/ M1 - 5266050 M3 - Japan Patent SN - 5266050 ER - TY - RPRT TI - High Strength Durable Micro and Nano-Fiber Fabrics Produced by Fibrillating Islands in the Sea Fibers AU - Pourdeyhimi, Behnam AU - Sharp, Stephen R. AU - Fedorova, Nataliya DA - 2013/5/2/ PY - 2013/5/2/ M1 - EP1907201 M3 - Germany Patent SN - EP1907201 ER - TY - RPRT TI - Composite Filter Media with High Surface Area Fibers AU - Pourdeyhimi, Behnam AU - Chappas, Walter DA - 2013/4/2/ PY - 2013/4/2/ M1 - 8,410,006 M3 - U.S. Patent SN - 8,410,006 ER - TY - JOUR TI - Impacts of high-speed waterjets on web structures AU - Suragani Venu, Lalith B. AU - Shim, Eunkyoung AU - Anantharamaiah, Nagendra AU - Pourdeyhimi, Behnam T2 - The Journal of The Textile Institute AB - AbstractHydroentangling, where a fabric is formed by striking of fine, closely spaced, high speed waterjets, is one of the fastest growing bonding methods in the nonwoven industry. Softness, drape, conformability, and relatively high strength are the major characteristics that make this bonding technology unique. Despite the method appeal, few understand the impact of waterjet on fabric structures. The primary function of waterjet is to produce fiber entangling, which induces web integrity. In this paper, we have analyzed the interaction of waterjets on web structures to provide a better understanding of the hydroentangling mechanism. We have successfully visualized and analyzed structures of entangled regions through 2D and 3D imaging techniques. The influence of water-jet pressure, jet diameter, and number of jets on hydroentangled web structures is reported.Keywords: nonwovenshydroentanglingthree-dimensional structuresentanglementfiber orientation AcknowledgementThe current work was supported by the Nonwovens Cooperative Research Center and its support is gratefully acknowledged. DA - 2013/9/9/ PY - 2013/9/9/ DO - 10.1080/00405000.2013.819613 VL - 105 IS - 4 SP - 430-443 J2 - The Journal of The Textile Institute LA - en OP - SN - 0040-5000 1754-2340 UR - http://dx.doi.org/10.1080/00405000.2013.819613 DB - Crossref ER - TY - JOUR TI - Interconnected, microporous hollow fibers for tissue engineering: Commercially relevant, industry standard scale-up manufacturing AU - Tuin, Stephen A. AU - Pourdeyhimi, Behnam AU - Loboa, Elizabeth G. T2 - Journal of Biomedical Materials Research Part A AB - Significant progress has been achieved in the field of tissue engineering to create functional tissue using biomimetic three-dimensional scaffolds that support cell growth, proliferation, and extracellular matrix production. However, many of these constructs are severely limited by poor nutrient diffusion throughout the tissue-engineered construct, resulting in cell death and tissue necrosis at the core. Nutrient transport can be improved by creation and use of scaffolds with hollow and microporous fibers, significantly improving permeability and nutrient diffusion. The purpose of this review is to highlight current technological advances in the fabrication of hollow fibers with interconnected pores throughout the fiber walls, with specific emphasis on developing hollow porous nonwoven fabrics for use as tissue engineering constructs via industry standard processing technologies: Spunbond processing and polymer melt extrusion. We outline current methodologies to create hollow and microporous scaffolds with the aim of translating that knowledge to the production of such fibers into nonwoven tissue engineering scaffolds via spunbond technology, a commercially relevant and viable melt extrusion manufacturing approach that allows for facile scale-up. DA - 2013/10/28/ PY - 2013/10/28/ DO - 10.1002/JBMA.35002 VL - 102 IS - 9 SP - 3311-3323 J2 - J. Biomed. Mater. Res. LA - en OP - SN - 1549-3296 UR - http://dx.doi.org/10.1002/jbm.a.35002 DB - Crossref ER - TY - JOUR TI - Hybrid mixed media nonwovens composed of macrofibers and microfibers. Part I: three-layer segmented pie configuration AU - Hollowell, Kendall B. AU - Anantharamaiah, Nagendra AU - Pourdeyhimi, Behnam T2 - Journal of the Textile Institute AB - Nonwoven fabrics, composed of microdenier fibers, can be easily created by using splittable bicomponents such as segmented pie. Hydroentangling has been shown as a very effective method for mechanically splitting these fibers. Such structures are known to form a densely packed nonwoven fabric with concomitant consequences in low porosity and tear strength. It is not, therefore, uncommon to insert a reinforcing scrim as a “rip-stop” mechanism in the middle of such structures to improve their properties, especially tear resistance. Instead, we propose a hybrid structure where the middle portion consists of solid homocomponent fibers, made from the same polymer as one of the components used in the bicomponent fibers, produced simultaneously during web formation, without causing noticeable changes in the fabrics’ overall texture. We report on the production and properties of fabrics composed entirely of bicomponent segmented pie fibers as well as our hybrid fabrics arranged in a three-layer configuration. DA - 2013/9// PY - 2013/9// DO - 10.1080/00405000.2013.767430 VL - 104 IS - 9 SP - 972-979 J2 - Journal of The Textile Institute LA - en OP - SN - 0040-5000 1754-2340 UR - http://dx.doi.org/10.1080/00405000.2013.767430 DB - Crossref ER - TY - JOUR TI - A simple simulation method for designing fibrous insulation materials AU - Arambakam, R. AU - Vahedi Tafreshi, H. AU - Pourdeyhimi, B. T2 - Materials & Design AB - Conductive heat in a fibrous material travels through both the air (interstitial fluid) and the fibers (solid phase). The numerical simulations reported in this paper are devised to study the effective thermal conductivity of fibrous media with different microstructural parameters. Simulations were conducted in 3-D fibrous geometries resembling the microstructure of a fibrous material. Assuming that the heat transfer through the interstitial fluid is independent of the geometrical parameters of the solid phase (for when the porosity is held constant), the energy equation was solved only for the solid structures, and the resulting values were used to predict the effective thermal conductivity of the whole media. This treatment allows us to drastically reduce the computational cost of such simulations. The results indicate that heat conduction through the solid fibrous structure increases by increasing the material’s solid volume fraction, fiber diameter, and fibers’ through-plane orientations. The in-plane orientation of the fibers, on the other hand, did not show any significant influence on the material’s conductivity. It was also shown that the microstructural parameters of fibrous insulations have negligible influence on the material’s performance if the conductivity of the solid phase is close to that of the interstitial fluid. DA - 2013/2// PY - 2013/2// DO - 10.1016/j.matdes.2012.07.058 VL - 44 SP - 99-106 J2 - Materials & Design LA - en OP - SN - 0261-3069 UR - http://dx.doi.org/10.1016/j.matdes.2012.07.058 DB - Crossref KW - Conductive heat transfer KW - Fibrous materials KW - Insulation materials KW - Numerical simulation ER - TY - JOUR TI - 3-D microscale simulation of dust-loading in thin flat-sheet filters: A comparison with 1-D macroscale simulations AU - Saleh, A.M. AU - Hosseini, S.A. AU - Vahedi Tafreshi, H. AU - Pourdeyhimi, B. T2 - Chemical Engineering Science AB - In this work, a microscale approach is undertaken to simulate the instantaneous pressure drop and collection efficiency of fibrous media exposed to particle loading, i.e., filter aging. The air flow field through 3-D disordered geometries representing the internal microstructure of a fibrous filter is obtained by numerically solving Stokes' equations. A Lagrangian approach is used to track the trajectory of particles through our virtual filter media and determine the filter's collection efficiency under different dust-load conditions. The calculations were conducted using the ANSYS CFD code enhanced with a series of in-house C++ subroutines. To better illustrate the value of such CPU-intensive 3-D microscale modeling, we compared the results of our simulations with those obtained from a 1-D macroscale model developed based on some of the pioneering studies reported in the literature. It was found that while the 1-D macroscale models can provide fast predictions for the pressure drop and collection efficiency of a given filter, they require a series of empirical correction factors or case-specific assumptions that limit their usage for design and development of new filter media. The 3-D microscale simulation methods, in contrast, are self-sufficient as they are developed based on first principles. With the current rate of progress in developing high-speed computers, it is expected that 3-D microscale simulations will be the preferred method of filter design in the near future. DA - 2013/8// PY - 2013/8// DO - 10.1016/J.CES.2013.06.007 VL - 99 SP - 284-291 J2 - Chemical Engineering Science LA - en OP - SN - 0009-2509 UR - http://dx.doi.org/10.1016/J.CES.2013.06.007 DB - Crossref KW - Aerosol KW - CFD KW - Filtration KW - Separations KW - Porous media KW - Fibrous media ER - TY - JOUR TI - Polymeric Systems Incorporating Plant Viral Nanoparticles for Tailored Release of Therapeutics AU - Honarbakhsh, Sara AU - Guenther, Richard H. AU - Willoughby, Julie A. AU - Lommel, Steven A. AU - Pourdeyhimi, Behnam T2 - ADVANCED HEALTHCARE MATERIALS AB - Therapeutic polylactide (PLA) nanofibrous matrices are fabricated by incorporating plant viral nanoparticles (PVNs) infused with fluorescent agents ethidium bromide (EtBr) and rhodamine (Rho), and cancer therapeutic doxorubicin (Dox). The native virus, Red clover necrotic mosaic virus (RCNMV), reversibly opens and closes upon exposure to the appropriate environmental stimuli. Infusing RCNMV with small molecules allows the incorporation of PVN(Active) into fibrous matrices via two methods: direct processing by in situ electrospinning of a polymer and PVNs solution or immersion of the matrix into a viral nanoparticle solution. Five organic solvents commonly in-use for electrospinning are evaluated for potential negative impact on RCNMV stability. In addition, leakage of rhodamine from the corresponding PVN(Rho) upon solvent exposure is determined. Incorporation of the PVN into the matrices are evaluated via transmission electron, scanning electron and fluorescent microscopies. Finally, the percent cumulative release of doxorubicin from both PLA nanofibers and PLA and polyethylene oxide (PEO) hybrid nanofibers demonstrate tailored release due to the incorporation of PVN(Dox) as compared to the control nanofibers with free Dox. Preliminary kinetic analysis results suggest a two-phase release profile with the first phase following a hindered Fickian transport mechanism for the release of Dox for the polymer-embedded PVNs. In contrast, the nanofiber matrices that incorporate PVNs through the immersion processing method followed a pseudo-first order kinetic transport mechanism. DA - 2013/7// PY - 2013/7// DO - 10.1002/adhm.201200434 VL - 2 IS - 7 SP - 1001-1007 SN - 2192-2659 KW - controlled release KW - drug delivery KW - nanofibers KW - plant viral nanoparticles KW - virus ER - TY - JOUR TI - Improving Poly(ethylene terephthalate) Through Self-nucleation AU - Joijode, Abhay S. AU - Hawkins, KaDesia AU - Tonelli, Alan E. T2 - MACROMOLECULAR MATERIALS AND ENGINEERING AB - Abstract As‐received poly(ethylene terephthalate) (asr‐PET) may be reorganized by precipitation from trifluoroacetic acid upon gradual addition to a large excess of rapidly stirred acetone (p‐PET). Unlike asr‐PET, p‐PET repeatedly crystallizes rapidly from the melt, and can be used in small quantities (a few %) as an effective self‐nucleating agent to control and improve the bulk semi‐crystalline morphology and properties of asr‐PET. Nuc‐PET film has significantly increased hardness and Young's modulus and is much less permeable to CO 2 , while its un‐drawn fibers exhibit higher tenacities and moduli. Because nuc‐PET contains no incompatible additives, it may be readily recycled. magnified image DA - 2013/11// PY - 2013/11// DO - 10.1002/mame.201200398 VL - 298 IS - 11 SP - 1190-1200 SN - 1439-2054 KW - crystallization KW - density and mechanical properties KW - nucleation KW - PET ER - TY - JOUR TI - Two-Stage Desorption-Controlled Release of Fluorescent Dye and Vitamin from Solution-Blown and Electrospun Nanofiber Mats Containing Porogens AU - Khansari, S. AU - Duzyer, S. AU - Sinha-Ray, S. AU - Hockenberger, A. S. AU - Yarin, A. L. AU - Pourdeyhimi, B. T2 - MOLECULAR PHARMACEUTICS AB - In the present work, a systematic study of the release kinetics of two embedded model drugs (one completely water soluble and one partially water soluble) from hydrophilic and hydrophobic nanofiber mats was conducted. Fluorescent dye Rhodamine B was used as a model hydrophilic drug in controlled release experiments after it was encapsulated in solution-blown soy-protein-containing hydrophilic nanofibers as well as in electrospun hydrophobic poly(ethylene terephthalate) (PET)-containing nanofibers. Vitamin B2 (riboflavin), a partially water-soluble model drug, was also encapsulated in hydrophobic PET-containing nanofiber mats, and its release kinetics was studied. The nanofiber mats were submerged in water, and the amount of drug released was tracked by fluorescence intensity. It was found that the release process saturates well below 100% release of the embedded compound. This is attributed to the fact that desorption is the limiting process in the release from biopolymer-containing nanofibers similar to the previously reported release from petroleum-derived polymer nanofibers. Release from monolithic as well as core-shell nanofibers was studied in the present work. Moreover, to facilitate the release and ultimately to approach 100% release, we also incorporated porogens, for example, poly(ethylene glycol), PEG. It was also found that the release rate can be controlled by the porogen choice in nanofibers. The effect of nanocracks created by leaching porogens on drug release was studied experimentally and evaluated theoretically, and the physical parameters characterizing the release process were established. The objective of the present work is a detailed experimental and theoretical investigation of controlled drug release from nanofibers facilitated by the presence of porogens. The novelty of this work is in forming nanofibers containing biodegradable and biocompatible soy proteins to facilitate controlled drug release as well as in measuring detailed quantitative characteristics of the desorption processes responsible for release of the model substance (fluorescent dye) and the vitamin (riboflavin) in the presence of porogens. DA - 2013/12// PY - 2013/12// DO - 10.1021/mp4003442 VL - 10 IS - 12 SP - 4509-4526 SN - 1543-8384 KW - controlled release KW - nanofibers KW - soy protein KW - porogens KW - desorption ER - TY - JOUR TI - Preservation of Cell Viability and Protein Conformation on Immobilization within Nanofibers via Electrospinning Functionalized Yeast AU - Canbolat, M. Fatih AU - Gera, Nimish AU - Tang, Christina AU - Monian, Brinda AU - Rao, Balaji M. AU - Pourdeyhimi, Behnam AU - Khan, Saad A. T2 - ACS APPLIED MATERIALS & INTERFACES AB - We investigate the immobilization of a model system of functionalized yeast that surface-display enhanced green fluorescent protein (eGFP) within chemically crosslinked polyvinyl alcohol (PVA) nanofibers. Yeast is incorporated into water insoluble nanofibrous materials by direct electrospinning with PVA followed by vapor phase chemical crosslinking of the polymer. Incorporation of yeast into the fibers is confirmed by elemental analysis and the viability is indicated by live/dead staining. Following electrospinning and crosslinking, we confirm that the yeast maintains its viability as well as the ability to express eGFP in the correct conformation. This method of processing functionalized yeast may thus be a powerful tool in the direct immobilization of properly folded, active enzymes within electrospun nanofibers with potential applications in biocatalysis. DA - 2013/10/9/ PY - 2013/10/9/ DO - 10.1021/am4022768 VL - 5 IS - 19 SP - 9349-9354 SN - 1944-8252 KW - electrospinning KW - nanofiber KW - protein KW - biocatalyst immobilization KW - yeast surface display ER - TY - JOUR TI - Biopolymer-Based Nanofiber Mats and Their Mechanical Characterization AU - Khansari, Shahrzad AU - Sinha-Ray, Suman AU - Yarin, Alexander L. AU - Pourdeyhimi, Behnam T2 - INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH AB - Nanofibers produced from plant- and animal-derived proteins using the solution-blowing method were collected and their mechanical properties were characterized and compared with those of synthetic polymer samples that were produced and collected similarly. Soy protein, zein, lignin, and cellulose acetate were the plant-derived proteins and silk protein (sericin) and bovine serum albumin were the animal-derived proteins used in the present work to form nanofibers by solution blowing. The aim of this work is to demonstrate that solution blowing can be successfully used to form nanotextured nonwovens from a number of biopolymers, which is of significant interest for a wide range of applications such as filtration, packaging, bioplastics and biomedical materials. Tensile tests were used to elucidate mechanical properties of such nanofiber mats. It was also shown that hot and cold drawing can be applied as a post-treatment to further enhance their mechanical performance. DA - 2013/10/30/ PY - 2013/10/30/ DO - 10.1021/ie402246x VL - 52 IS - 43 SP - 15104-15113 SN - 0888-5885 ER - TY - JOUR TI - Influence of Subsurface Hybrid Material Growth on the Mechanical Properties of Atomic Layer Deposited Thin Films on Polymers AU - Sun, Yujie AU - Padbury, Richard P. AU - Akyildiz, Halil I. AU - Goertz, Matthew P. AU - Palmer, Jeremy A. AU - Jur, Jesse S. T2 - CHEMICAL VAPOR DEPOSITION AB - Abstract The mechanical properties of atomic layer deposition (ALD) coatings play a key role in their long‐term use as encapsulation barriers for organic‐based, flexible, electronic devices. Nano‐indentation characteristics and flexure testing of nanometer‐scale alumina on polyamide 6 (PA6) films are investigated to determine the influence of a sub‐surface hybrid layer formed during the ALD process. This hybrid layer is observed to affect the mechanical performance of the thin films, in particular at lower processing temperatures. This work has important consequences on how ALD materials need to be applied and evaluated on polymers for application as encapsulation barrier layers. DA - 2013/6// PY - 2013/6// DO - 10.1002/cvde.201207042 VL - 19 IS - 4-6 SP - 134-141 SN - 1521-3862 KW - ALD nucleation KW - Flexibility KW - Hybrid layer KW - Mechanical properties KW - PA6 ER - TY - JOUR TI - Induced wetting of polytetrafluoroethylene by atomic layer deposition for application of aqueous-based nanoparticle inks AU - Halbur, Jonathan C. AU - Padbury, Richard P. AU - Jur, Jesse S. T2 - MATERIALS LETTERS AB - Atomic layer deposition of aluminum oxide is shown to control the surface energy and wetting properties of polytetrafluoroethylene (PTFE) films and membranes. Independent of deposition temperature, gradual and abrupt wetting transitions were observed for PTFE films and membranes, respectively. To assess the enhanced compatibility of treated PTFE substrates with nanoparticle inks, drop casting and inkjet printing of silver nanoparticle solutions are performed and analyzed by optical microscopy and time of flight secondary ion mass spectroscopy. Untreated PTFE substrates showed poor compatibility with the nanoparticle inks, drying in a coffee ring pattern, whereas aluminum oxide treated PTFE substrates exhibited uniform silver nanoparticle distribution after drying. DA - 2013/6/15/ PY - 2013/6/15/ DO - 10.1016/j.matlet.2013.03.063 VL - 101 SP - 25-28 SN - 1873-4979 KW - PTFE KW - Atomic layer deposition KW - Nanoparticle compatibility KW - Surface energy KW - Wetting KW - Al2O3 ER - TY - JOUR TI - Generation and Properties of Antibacterial Coatings Based on Electrostatic Attachment of Silver Nanoparticles to Protein-Coated Polypropylene Fibers AU - Goli, Kiran K. AU - Gera, Nimish AU - Liu, Xiaomeng AU - Rao, Balaji M. AU - Rojas, Orlando J. AU - Genzer, Jan T2 - ACS APPLIED MATERIALS & INTERFACES AB - We present a simple method for attaching silver nanoparticles to polypropylene (PP) fibers in a two-step process to impart antibacterial properties. Specifically, PP fibers are pretreated by the adsorption from an aqueous solution of heat-denatured lysozyme (LYS) followed by LYS cross-linking using glutaraldehyde and sodium borohydride. At neutral pH, the surface of the adsorbed LYS layer is enriched with numerous positive charges. Silver nanoparticles (AgNPs) capped with trisodium citrate are subsequently deposited onto the protein-coated PP. Nanoparticle binding is mediated by electrostatic interactions between the positively charged LYS layer and the negatively charged AgNPs. The density of AgNPs deposited on PP depends on the amount of protein adsorbed on the surface. UV-vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy are employed to follow all preparation steps and to characterize the resulting functional surfaces. The antibacterial activity of the modified surfaces is tested against gram negative bacteria Escherichia coli (E. coli). Overall, our results show that PP surfaces coated with AgNPs exhibit excellent antibacterial activity with 100% removal efficiency. DA - 2013/6/12/ PY - 2013/6/12/ DO - 10.1021/am4011644 VL - 5 IS - 11 SP - 5298-5306 SN - 1944-8252 KW - antibacterial KW - polypropylene KW - protein adsorption KW - nanoparticle KW - functional coating ER - TY - JOUR TI - Blowing drops off a filament AU - Sahu, R. P. AU - Sinha-Ray, S. AU - Yarin, A. L. AU - Pourdeyhimi, B. T2 - Soft Matter AB - The first part of this work is devoted to the experimental study of oil drop motion along a filament due to the parallel air jet blowing. The drop displacement and velocity along the filament are measured. A number of accompanying phenomena are observed. These include drop stick–slip motion and shape oscillations, shedding of a tail along the filament, the tail capillary instability and drop recoil motion. The experimental observations are rationalized in the framework of several simplified models, and the origin of several observed phenomena is elucidated. In the second part of this work, experiments with cross-flow of the surrounding gas relative to the filament with an oil drop on it are conducted, with the gas velocity being in the 7.23 to 22.7 m s−1 range. The Weber number varied from 2 to 40 and the Ohnesorge number was in the 0.07 to 0.8 range. The lower and upper critical Weber numbers were introduced to distinguish between the beginning of the drop blowing off the filament and the onset of the bag-stamen drop breakup. The range of the Weber number between these two critical values is filled with three types of vibrational breakup: V1 (a balloon-like drop being blown off), V2 (a drop on a single stamen being blown off), and V3 (a drop on a double stamen being blown off). At still higher values of the Weber number, the bag-stamen breakup can be replaced by the bag type of breakup depending on a slight difference in the blowing speed, or the former and the latter can become intermittent depending on the drop asymmetry relative to the filament. The Weber number/Ohnesorge number plane was delineated into domains corresponding to different breakup regimes, the statistics of the residual liquid portion left on a filament was established and drop hopping across neighboring filaments was studied. DA - 2013/// PY - 2013/// DO - 10.1039/c3sm50618e VL - 9 IS - 26 SP - 6053 J2 - Soft Matter LA - en OP - SN - 1744-683X 1744-6848 UR - http://dx.doi.org/10.1039/c3sm50618e DB - Crossref ER - TY - JOUR TI - Glass-transition temperatures of nanostructured amorphous bulk polymers and their blends AU - Joijode, Abhay S. AU - Antony, Gerry J. AU - Tonelli, Alan E. T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - ABSTRACT Nanostructured amorphous bulk polymer samples were produced by processing them with small molecule hosts. Urea (U) and gamma‐cyclodextrin (γ‐CD) were utilized to form crystalline inclusion compounds (ICs) with low and high molecular weight as‐received (asr‐) poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA), and their blends as included guests. Upon careful removal of the host crystalline U and γ‐CD lattices, nanostructured coalesced (c‐) bulk PVAc, PMMA, and PVAc/PMMA blend samples were obtained, and their glass‐transition temperatures, T g s, measured. In addition, non‐stoichiometric (n‐s)‐IC samples of each were formed with γ‐CD as the host. The T g s of the un‐threaded, un‐included portions of their chains were observed as a function of their degree of inclusion. In all the cases, these nanostructured PVAc and PMMA samples exhibited T g s elevated above those of their as‐received and solution‐cast samples. Based on their comparison, several conclusions were reached concerning how their molecular weights, the organization of chains in their coalesced samples, and the degree of constraint experienced by un‐included portions of their chains in (n‐s)‐γ‐CD‐IC samples with different stoichiometries affect their chain mobilities and resultant T g s. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1041–1050 DA - 2013/7/1/ PY - 2013/7/1/ DO - 10.1002/polb.23306 VL - 51 IS - 13 SP - 1041-1050 SN - 1099-0488 KW - amorphous KW - blending KW - blends KW - glass transition KW - nano-structured KW - polymer glass-transitions ER - TY - JOUR TI - Effects of surfactants on the microstructures of electrospun polyacrylonitrile nanofibers and their carbonized analogs AU - Aykut, Yakup AU - Pourdeyhimi, Behnam AU - Khan, Saad A. T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - ABSTRACT In this study, the influence of surfactants on the processability of electrospun polyacrylonitrile (PAN) nanofibers and their carbonized analogs was investigated. The surfactants employed in this effort are Triton X‐100 (nonionic surfactant, SF‐N), sodium dodecyl sulfate (SDS) (anionic surfactant, SF‐A), and hexadecyltrimethylammonium bromide (HDTMAB) (cationic surfactant, SF‐C). Interactions between electrospun PAN and the surfactants, reflected in effects on as‐spun and carbonized nanofiber morphologies and microstructures, were explored. The results show that uniform nanofibers are obtained when cationic and anionic surfactants (surfactant free and nonionic surfactants) are utilized in the preparation of electrospun PAN. In contrast, a bead‐on‐a‐string morphology results when the aniconic and cationic surfactants are present, and defect structure is enhanced with cationic surfactant addition. Moreover, fiber breakage is observed when the nonionic surfactant Triton X‐100 is employed for electrospinning. After carbonizaition, the PAN polymers were observed to have less ordered structures with addition of any type of surfactant used for electrospinning and the disorder becomes more pronounced when the anionic surfactant is utilized. Owing to the fact that microstructure defects create midband gap states that enable more electrons to be emitted from the fiber, an enhancement of electron emission is observed for PAN electrospun in the presence of the anionic surfactant. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3726–3735, 2013 DA - 2013/12/5/ PY - 2013/12/5/ DO - 10.1002/app.39637 VL - 130 IS - 5 SP - 3726-3735 SN - 1097-4628 KW - electrospinning KW - nanostructured polymers KW - morphology ER - TY - JOUR TI - Effect of DMDBS (3: 2, 4-bis(3,4-dimethyldibenzylidene) sorbitol) and NA11 (sodium 2,2-methylene-bis(4,6-di-tertbutylphenyl)-phosphate) on electret properties of polypropylene filaments AU - Kilic, Ali AU - Shim, Eunkyoung AU - Yeom, Bong Yeol AU - Pourdeyhimi, Behnam T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - ABSTRACT Polypropylene (PP) composite filaments containing two different nucleating agents—DMDBS (3 : 2, 4‐bis(3,4‐dimethyldibenzylidene) sorbitol) and NA11 (sodium 2,2′‐methylene‐bis(4,6‐di‐tertbutylphenyl)‐phosphate) were melt spun to modify polymer electrostatic charging characteristics. Sample filaments were charged with a corona instrument and their surface potentials were measured. Initial surface potential as well as potential stability was monitored through an accelerated decay procedure. NA11 was found to be more efficient as an electret additive leading to a 50% increase in charge stability. Filaments with DMDBS exhibited a faster decay. Charging at elevated temperatures resulted in enhanced charge density and stability for both additives. The fiber microstructure was examined by Wide Angle X‐ray Diffraction and Differential Scanning Calorimetry. Rather than reducing the crystal sizes, X‐Ray diffractograms suggest that the crystal size increases with the addition of nucleating agents, while the degree of crystallinity appears to remain unaltered. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2068–2075, 2013 DA - 2013/11/5/ PY - 2013/11/5/ DO - 10.1002/app.39392 VL - 130 IS - 3 SP - 2068-2075 SN - 1097-4628 KW - polyolefins KW - fibers KW - separation techniques KW - blends ER - TY - JOUR TI - Synthesis and characterization of silver/lithium cobalt oxide (Ag/LiCoO2) nanofibers via sol-gel electrospinning AU - Aykut, Yakup AU - Pourdeyhimi, Behnam AU - Khan, Saad A. T2 - JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS AB - We report on the preparation and characterization of Ag/LiCoO2 nanofibers (NFs) via the sol–gel electrospinning (ES) technique. Ag nanoparticles (NPs) were produced in an aqueous polyvinyl pyrrolidone (PVP) solution by using AgNO3 precursor. A viscous lithium acetate/cobalt acetate/polyvinylalcohol/water (LiAc/(CoAc)2/PVA/water) solution was prepared separately. A Ag NPs/PVP/water solution was prepared and added to this viscous solution and magnetically stirred to obtain the final homogeneous electrospinning solution. After establishing the proper electrospinning conditions, as-spun precursor Ag/LiAc/Co(Ac)2/PVA/PVP NFs were formed and calcined in air at a temperature of 600 °C for 3 h to form well-crystallized porous Ag/LiCoO2 NFs. Various analytical characterization techniques such as UV–vis, SEM, TEM, TGA, XRD, and XPS were performed to analyze Ag NPs, as-spun and calcined NFs. It was established that Ag NPs in the precursor Ag/LiAc/Co(Ac)2/PVA/PVP NFs are highly self-aligned as a result of the behavior of Ag in the electric field of the electrospinning setup and the interaction of Ag ions with Li and Co ions in the NF. Ag/LiCoO2 NFs exhibit a nanoporous structure compared with un-doped LiCoO2 NFs because the atomic radius of Ag is larger than the radius of Co and Li ion; thus, no substitution between Ag and Li or Ag and Co atoms occurs, and Ag NPs are located at the interlayer of LiCoO2 while some are left in the fiber. DA - 2013/11// PY - 2013/11// DO - 10.1016/j.jpcs.2013.05.021 VL - 74 IS - 11 SP - 1538-1545 SN - 1879-2553 KW - Nanostructures KW - Sol-gel growth KW - Crystal structure KW - Microstructure ER - TY - JOUR TI - Catalytic graphitization and formation of macroporous-activated carbon nanofibers from salt-induced and H2S-treated polyacrylonitrile AU - Aykut, Yakup AU - Pourdeyhimi, Behnam AU - Khan, Saad A. T2 - JOURNAL OF MATERIALS SCIENCE DA - 2013/11// PY - 2013/11// DO - 10.1007/s10853-013-7463-x VL - 48 IS - 22 SP - 7783-7790 SN - 1573-4803 ER - TY - JOUR TI - Modelling and experimental studies of air permeability of nonuniform nonwoven fibrous porous media AU - Das, Dipayan AU - Ishtiaque, S. M. AU - Rao, S. V. Ajab AU - Pourdeyhimi, Behnam T2 - FIBERS AND POLYMERS DA - 2013/3// PY - 2013/3// DO - 10.1007/s12221-013-0494-8 VL - 14 IS - 3 SP - 494-499 SN - 1875-0052 KW - Nonwoven KW - Air permeability KW - Packing density KW - Nonuniformity KW - Model KW - Experiment ER - TY - JOUR TI - Improving electret properties of PP filaments with barium titanate AU - Kilic, Ali AU - Shim, Eunkyoung AU - Yeom, Bong Yeol AU - Pourdeyhimi, Behnam T2 - JOURNAL OF ELECTROSTATICS AB - Barium titanate (BaTiO3) containing polypropylene (PP) composite filaments were melt spun to modify polymer electrostatic charging characteristics. Sample filaments were charged with a corona instrument and their surface potentials were measured. Initial surface potential as well as potential stability was monitored through an accelerated decay procedure. It was found that both BaTiO3 concentration and charging temperature influence the charging characteristics of the fibers. When BaTiO3/PP composite filaments were charged at 130 °C, significant enhancements were observed when compared to samples charged at room temperature. The distribution of BaTiO3 particles within the filaments and changes in the crystal structure were also examined. DA - 2013/2// PY - 2013/2// DO - 10.1016/j.elstat.2012.11.005 VL - 71 IS - 1 SP - 41-47 SN - 0304-3886 KW - Polypropylene KW - Barium titanate KW - Electret filters ER - TY - JOUR TI - Acoustical absorptive properties of spunbonded nonwovens made from islands-in-the-sea bicomponent filaments AU - Suvari, Fatih AU - Ulcay, Yusuf AU - Maze, Benoit AU - Pourdeyhimi, Behnam T2 - JOURNAL OF THE TEXTILE INSTITUTE AB - Abstract In this paper, we report on the acoustical absorptive behavior of spunbonded nonwovens that contain bicomponent islands-in-the-sea filaments. Nylon 6 (PA6) and polyethylene were used as the islands and the sea polymers, respectively. Spunbonded webs made with islands-in-the-sea bicomponent filaments with island counts of 1, 7, 19, 37, and 108 were produced at the Nonwovens Institute’s pilot facilities at NC State University. The filaments were fibrillated by hydroentangling, where high-speed water jets were used to fibrillate the fiber and ‘free’ the islands. The influence of the number of islands on acoustical absorptive behavior of the spunbonded nonwovens was investigated. A comparison of acoustical absorptive properties of multi-layer islands-in-the-sea nonwoven and high loft nonwoven was also performed to evaluate the potential use of spunbonded nonwovens made from islands-in-the-sea bicomponent filaments in place of bulky fibrous sound absorbers. Results have shown that multi-layer 108 nonwoven islands were better acoustic absorbers at nearly half of the frequency range. Spunbonded nonwovens made from islands-in-the-sea bicomponent filaments can be a good alternative in applications where there is desire to replace bulky fibrous sound absorbers. Keywords: spunbondingsound absorptionbicomponent filamentsislands-in-the-sea Acknowledgements This work was supported by a grant from the Nonwovens Institute. Their support is gratefully acknowledged. The first author would like to thank TUBITAK for individual support. DA - 2013/4/1/ PY - 2013/4/1/ DO - 10.1080/00405000.2012.740330 VL - 104 IS - 4 SP - 438-445 SN - 1754-2340 KW - spunbonding KW - sound absorption KW - bicomponent filaments KW - islands-in-the-sea ER - TY - JOUR TI - Synthesis of Mixed Ceramic MgxZn1-xO Nanofibers via Mg2+ Doping Using Sol-Gel Electrospinning AU - Aykut, Yakup AU - Parsons, Gregory N. AU - Pourdeyhimi, Behnam AU - Khan, Saad A. T2 - LANGMUIR AB - We report on the synthesis of tuned energy band gap MgxZn1–xO nanofibers (NFs) with different Mg2+ content via the sol–gel electrospinning (ES) technique wherein the addition of the doping material affects not only the morphologies of as-spun ZnAc/PVA and MgAc/ZnAc/PVA nanofibers but also the crystal microstructure and optical properties of calcined ZnO and MgxZn1–xO nanofibers. Following an appropriate aqueous solution preparation of magnesium acetate (MgAc) and zinc acetate (ZnAc) with poly(vinyl alcohol) (PVA), electrospinning is performed and then as-spun nanofibers are calcined in an air atmosphere at 600 °C for 3 h. As-spun and calcined nanofiber diameters and morphologies are evaluated with scanning (SEM) and transmission (TEM) electron microscopies, whereas crystalline microstructural interpretations of ZnO and MgxZn1–xO are conducted with wide-angle X-ray diffraction spectra (XRD). Surface chemical composition and elemental evaluation of calcined nanofibers are examined with X-ray photoelectron spectroscopy (XPS), and optical properties and crystal defect analyses of the calcined nanofibers are conducted with photoluminescence spectra (PL). We observe a sharp reduction in fiber diameter upon calcination as a result of the removal of organic species from the fibers and conversion of ceramic precursors into ceramic nanofibers, and the appearance of a range of fiber morphologies from “bead in a string” to “sesame seed” coverage depending on fiber composition. Because Zn2+ and Mg2+ have similar ionicity and atomic radii, some Zn2+ atoms are replaced by Mg2+ atoms in the crystals, leading to a change in the properties of crystal lattices. The band gap energy of the calcined fibers increases significantly with addition of Mg2+ along with an increase in the ultraviolet (UV) photoluminescence emission of the fibers. DA - 2013/3/26/ PY - 2013/3/26/ DO - 10.1021/la400281c VL - 29 IS - 12 SP - 4159-4166 SN - 0743-7463 ER - TY - JOUR TI - Prediction of angular and mass distribution in meltblown polymer lay-down AU - Sinha-Ray, S. AU - Yarin, A. L. AU - Pourdeyhimi, B. T2 - POLYMER AB - Predictions of the properties of meltblown polymer nonwovens require knowledge of the angular fiber distribution in lay-down, as well as the deposited mass distribution. In the present work these two important characteristics are predicted using our previously developed model describing multiple three-dimensional viscoelastic polymer jets in meltblowing and their deposition onto a moving screen normal to the blowing direction. The results are important for predictions of strength of meltblown nonwovens. DA - 2013/1/24/ PY - 2013/1/24/ DO - 10.1016/j.polymer.2012.11.061 VL - 54 IS - 2 SP - 860-872 SN - 0032-3861 KW - Angular and mass distribution KW - Forming microfibers KW - Polymer lay-down ER - TY - JOUR TI - Ultrastretchable Fibers with Metallic Conductivity Using a Liquid Metal Alloy Core AU - Zhu, Shu AU - So, Ju-Hee AU - Mays, Robin AU - Desai, Sharvil AU - Barnes, William R. AU - Pourdeyhimi, Behnam AU - Dickey, Michael D. T2 - ADVANCED FUNCTIONAL MATERIALS AB - Abstract The fabrication and characterization of fibers that are ultrastretchable and have metallic electrical conductivity are described. The fibers consist of a liquid metal alloy, eutectic gallium indium (EGaIn), injected into the core of stretchable hollow fibers composed of a triblock copolymer, poly[styrene‐ b ‐(ethylene‐ co ‐butylene)‐ b ‐styrene] (SEBS) resin. The hollow fibers are easy to mass‐produce with controlled size using commercially available melt processing methods. The fibers are similar to conventional metallic wires, but can be stretched orders of magnitude further while retaining electrical conductivity. Mechanical measurements with and without the liquid metal inside the fibers show the liquid core has a negligible impact on the mechanical properties of the fibers, which is in contrast to most conductive composite fibers. The fibers also maintain the same tactile properties with and without the metal. Electrical measurements show that the fibers increase resistance as the fiber elongates and the cross sectional area narrows. Fibers with larger diameters change from a triangular to a more circular cross‐section during stretching, which has the appeal of lowering the resistance below that predicted by theory. To demonstrate their utility, the ultrastretchable fibers are used as stretchable wires for earphones and for a battery charger and perform as well as their conventional parts. DA - 2013/5/13/ PY - 2013/5/13/ DO - 10.1002/adfm.201202405 VL - 23 IS - 18 SP - 2308-2314 SN - 1616-3028 KW - stretchable electronics KW - eutectic gallium indium KW - conductive fibers ER - TY - JOUR TI - Characterisation and numerical modelling of complex deformation behaviour in thermally bonded nonwovens AU - Farukh, Farukh AU - Demirci, Emrah AU - Sabuncuoglu, Baris AU - Acar, Memis AU - Pourdeyhimi, Behnam AU - Silberschmidt, Vadim V. T2 - COMPUTATIONAL MATERIALS SCIENCE AB - A complex time-dependent deformation and damage behaviour in polymer-based nonwovens are analysed under conditions of multi-stage uniaxial loading. Elastic–plastic and viscous properties of a polypropylene-based fabric are obtained by series of tensile, creep and relaxation tests performed on single fibres extracted from the studied fabric. These properties are implemented in a finite-element (FE) model of nonwoven with direct introduction of fibres according to their actual orientation distribution in order to simulate the rate-dependent deformation up to the onset of damage in thermally bonded nonwovens. The predictions of FE simulations are compared with the experimental data of multi-stage deformation tensile tests and a good agreement is obtained including the mechanisms of deformation. Due to direct modelling of fibres based on their actual orientation distribution and implementation of viscous properties, the model could be extended to other types of polymer-based random fibrous networks. DA - 2013/4// PY - 2013/4// DO - 10.1016/j.commatsci.2013.01.007 VL - 71 SP - 165-171 SN - 1879-0801 KW - Nonwoven KW - Polypropylene KW - Viscous KW - Finite element KW - Damage ER - TY - JOUR TI - Antibacterial activity of photocatalytic electrospun titania nanofiber mats and solution-blown soy protein nanofiber mats decorated with silver nanoparticles AU - Zhang, Yiyun AU - Lee, Min Wook AU - An, Seongpil AU - Sinha-Ray, Suman AU - Khansari, Shahrzad AU - Joshi, Bhavana AU - Hong, Seungkwan AU - Hong, Joo-Hyun AU - Kim, Jae-Jin AU - Pourdeyhimi, B. AU - Yoon, Sam S. AU - Yarin, Alexander L. T2 - CATALYSIS COMMUNICATIONS AB - Highly porous photocatalytic titania nanoparticle decorated nanofibers were fabricated by electrospinning nylon 6 nanofibers onto flexible substrates and electrospraying TiO2 nanoparticles onto them. Film morphology and crystalline phase were measured by SEM and XRD. The titania films showed excellent photokilling capabilities against E. coli colonies and photodegradation of methylene blue under moderately weak UV exposure (≤ 0.6 mW/cm2 on a 15-cm illumination distance). In addition, solution blowing was used to form soy protein-containing nanofibers which were decorated with silver nanoparticles. These nanofibers demonstrated significant antibacterial activity against E. coli colonies without exposure to UV light. The nano-textured materials developed in this work can find economically viable applications in water purification technology and in biotechnology. The two methods of nanofiber production employed in this work differ in their rate with electrospinning being much slower than the solution blowing. The electrospun nanofiber mats are denser than the solution-blown ones due to a smaller inter-fiber pore size. The antibacterial activity of the two materials produced (electrospun titania nanoparticle decorated nanofibers and silver-nanoparticle-decorated solution-blown nanofibers) are complimentary, as the materials can be effective with and without UV light, respectively. DA - 2013/4/5/ PY - 2013/4/5/ DO - 10.1016/j.catcom.2013.01.002 VL - 34 SP - 35-40 SN - 1873-3905 KW - Antibacterial KW - Electrospinning KW - Titania KW - Soy protein KW - Solution blowing KW - Silver nanoparticles ER - TY - JOUR TI - Supersonic nanoblowing: a new ultra-stiff phase of nylon 6 in 20-50 nm confinement AU - Sinha-Ray, Suman AU - Lee, Min Wook AU - Sinha-Ray, Sumit AU - An, Seongpil AU - Pourdeyhimi, Behnam AU - Yoon, Sam S. AU - Yarin, Alexander L. T2 - JOURNAL OF MATERIALS CHEMISTRY C AB - The 20–50 nm nanofibers hold great promise as functional fabrics, biomedical materials, filters, fuel cell membranes, ultra-speed fiber optics, electronics and sensorics. In our novel process of supersonic solution blowing of nylon-6, 20–50 nm nanofibers are obtained. Here we found a new phase of nylon-6, which differs from the known α-, β-, γ-, δ- and λ-phases, presenting itself as a novel χ-phase. It is characterized by the decrease of CH2 stretching, a shift of –NH stretching, a different type of hydrogen bond and a ten-fold increase in Young's modulus compared to those of post-processed macroscopic nylon fibers. DA - 2013/// PY - 2013/// DO - 10.1039/c3tc30248b VL - 1 IS - 21 SP - 3491-3498 SN - 2050-7534 ER - TY - JOUR TI - Meso-scale deformation and damage in thermally bonded nonwovens AU - Farukh, Farukh AU - Demirci, Emrah AU - Acar, Memis AU - Pourdeyhimi, Behnam AU - Silberschmidt, Vadim V. T2 - JOURNAL OF MATERIALS SCIENCE AB - Thermal bonding is the fastest and the cheapest technique for manufacturing nonwovens. Understanding mechanical behaviour of these materials, especially related to damage, can aid in design of products containing nonwoven parts. A finite element (FE) model incorporating mechanical properties related to damage such as maximum stress and strain at failure of fabric’s fibres would be a powerful design and optimisation tool. In this study, polypropylene-based thermally bonded nonwovens manufactured at optimal processing conditions were used as a model system. A damage behaviour of the nonwoven fabric is governed by its single-fibre properties, which are obtained by conducting tensile tests over a wide range of strain rates. The fibres for the tests were extracted from the nonwoven fabric in a way that a single bond point was attached at both ends of each fibre. Additionally, similar tests were performed on unprocessed fibres, which form the nonwoven. Those experiments not only provided insight into damage mechanisms of fibres in thermally bonded nonwovens but also demonstrated a significant drop in magnitudes of failure stress and respective strain in fibres due to the bonding process. A novel technique was introduced in this study to develop damage criteria based on the deformation and fracture behaviour of a single fibre in a thermally bonded nonwoven fabric. The damage behaviour of a fibrous network within the thermally bonded fabric was simulated with a FE model consisting of a number of fibres attached to two neighbouring bond points. Additionally, various arrangements of fibres’ orientation and material properties were implemented in the model to analyse the respective effects. DA - 2013/3// PY - 2013/3// DO - 10.1007/s10853-012-7013-y VL - 48 IS - 6 SP - 2334-2345 SN - 1573-4803 ER - TY - JOUR TI - Fabrication of nanofiber meltblown membranes and their filtration properties AU - Hassan, Mohammad Abouelreesh AU - Yeom, Bong Yeol AU - Wilkie, Arnold AU - Pourdeyhimi, Behnam AU - Khan, Saad. A. T2 - JOURNAL OF MEMBRANE SCIENCE AB - 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 μm. 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. DA - 2013/1// PY - 2013/1// DO - 10.1016/j.memsci.2012.09.050 VL - 427 SP - 336-344 SN - 1873-3123 KW - Nanofibers KW - Meltbowing KW - Filtration KW - Nonwoven membranes KW - HEPA filters ER -