TY - RPRT TI - High surface area fiber and textiles made from the same AU - Pourdeyhimi, B. AU - Chappas, W. DA - 2012/3/6/ PY - 2012/3/6/ M1 - US8129019B2 M3 - Patent SN - US8129019B2 ER - TY - RPRT TI - Staple fiber durable nonwoven fabrics AU - Anantharamaiah, N. AU - Pourdeyhimi, B. DA - 2012/4/3/ PY - 2012/4/3/ M1 - US8148279B2 M3 - Patent SN - US8148279B2 ER - TY - RPRT TI - Non-woven textile microwave patch antennas and components AU - Deaett, MA AU - Weedon, WH, III AU - Pourdeyhimi, Behnam DA - 2012/5/8/ PY - 2012/5/8/ M1 - US8174449B2 M3 - Patent SN - US8174449B2 ER - TY - BOOK TI - Introduction to Nonwovens Technology AU - Batra, S.K. AU - Pourdeyhimi, B. DA - 2012/// PY - 2012/// PB - Destech Publishing SN - 9781605950372 ER - TY - CONF TI - Green Materials: Strength of Soy Protein Nanofiber Mats AU - Khansari, S. AU - Sinha-Ray, S. AU - Yarin, A. AU - Pourdeyhimi, B. T2 - National Science Foundation, Division of Civil, Mechanical and Manufacturing Innovation (NSF CMMI) Engineering Research and Innovation Conference C2 - 2012/// CY - Northeastern University, Boston, MA DA - 2012/// PY - 2012/7/9/ ER - TY - CONF TI - Use of Additives to Enhance Electrostatic Charge in Filters AU - Kilic, A. AU - Shim, E. AU - Pourdeyhimi, B. T2 - Filtrex C2 - 2012/10// CY - Cologne, Germany DA - 2012/10// PY - 2012/10// ER - TY - CONF TI - Stretch and Recovery, Stretch Nonwovens AU - Pourdeyhimi, B. T2 - TechTextil C2 - 2012/4// CY - Atlanta, Georgia DA - 2012/4// PY - 2012/4// ER - TY - CONF TI - Pulsatile Fluid Flow Increases RUNX2 Expression in Human Adipose Derived Stem Cells Cultured on Novel Three-Dimensional High Surface Area Poly(L-Lactic Acid) Scaffolds 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 - 14th Annual North Carolina Tissue Engineering and Regenerative Medicine Society Conference C2 - 2012/9// C3 - Proceedings of the 14th Annual North Carolina Tissue Engineering and Regenerative Medicine Society Conference CY - Raleigh, NC DA - 2012/9// PY - 2012/9// ER - TY - CONF TI - Biomimetic Forces and Scaffolds to Control Human Stem Cell Fate AU - Loboa, E.G. AU - Bodle, J. AU - Charoenpanich, A. AU - Mathieu, P. AU - Mohiti-Asli, M. AU - Tuin, S.A. AU - Williams, J. T2 - 11th Annual Meeting of the New Jersey Symposium on Biomaterials Science C2 - 2012/10// C3 - Proceedings of the 11th Annual Meeting of the New Jersey Symposium on Biomaterials Science CY - New Brunswick, NJ DA - 2012/10// PY - 2012/10// ER - TY - CONF TI - Novel High Surface Area Poly(L-Lactic Acid) Winged Fiber Scaffolds Increase RUNX2 Expression of Human Adipose Derive Stem Cells Exposed to Shear Stress 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 - Annual Joint Meeting of the Materials Research Society and the Materials Information Society C2 - 2012/11// C3 - Proceedings of the Annual Joint Meeting of the Materials Research Society and the Materials Information Society CY - Raleigh, NC DA - 2012/11// PY - 2012/11// ER - TY - CONF TI - Durable Nonwovens with Stretch and Recovery AU - Pourdeyhimi, B. T2 - Man Made Fiber Conference C2 - 2012/9// CY - Dornbirn, Austria DA - 2012/9// PY - 2012/9// ER - TY - CONF TI - Stretch and Recovery, Stretch Nonwovens AU - Pourdeyhimi, B. T2 - Man Made Fiber Conference C2 - 2012/9// CY - Dornbirn, Austria DA - 2012/9// PY - 2012/9// ER - TY - CONF TI - A New Generation of Micro-Nano Fiber Nonwovens AU - Pourdeyhimi, B. T2 - Nonwovens Research Academy C2 - 2012/4// CY - Gothenburg, Sweden DA - 2012/4// PY - 2012/4// ER - TY - RPRT TI - Mixed Fiber and Nonwoven Fabrics Made from the Same AU - Pourdeyhimi, Behnam DA - 2012/7/4/ PY - 2012/7/4/ M1 - 101939469 M3 - China Patent SN - 101939469 ER - TY - RPRT TI - High Strength Durable Micro and Nano-Fiber Fabrics Produced by Fibrillating Islands in the Sea Fibers AU - Pourdeyhimi, Behnam DA - 2012/10/10/ PY - 2012/10/10/ M1 - 101641469 M3 - China Patent SN - 101641469 ER - TY - RPRT TI - Mixed Fiber and Nonwoven Fabrics Made from the Same AU - Pourdeyhimi, Behnam DA - 2012/5/1/ PY - 2012/5/1/ M1 - 2179081 M3 - Germany Patent SN - 2179081 ER - TY - RPRT TI - Mixed Fiber and Nonwoven Fabrics Made from the Same AU - Pourdeyhimi, Behnam DA - 2012/12/12/ PY - 2012/12/12/ M1 - 10-1210973 M3 - Korea Patent SN - 10-1210973 ER - TY - RPRT TI - An Improved Composite Filter Media with High Surface Area Fibers AU - Pourdeyhimi, Behnam DA - 2012/12/30/ PY - 2012/12/30/ M1 - 101617072 M3 - China Patent SN - 101617072 ER - TY - JOUR TI - Effect of Chemical and Physical Cross-Linking on Tensile Characteristics of Solution-Blown Soy Protein Nanofiber Mats AU - Sinha-Ray, S. AU - Khansari, S. AU - Yarin, A. L. AU - Pourdeyhimi, B. T2 - Industrial & Engineering Chemistry Research AB - Solution-blown soy protein/nylon 6 nanofibers, 40/60 and 50/50 wt/wt %, were collected on a rotating aluminum drum in order to form a mat. The collected fiber mats were bonded both chemically (using aldehydes and ionic cross-linkers) and physically (by means of wet and thermal treatment) to increase the tensile strength to increase the range of application of such green nonwovens. Chemical cross-linkers bond different amino groups, primary amides, and sulfhydryl groups in protein structure. This is beneficial for the enhancement of tensile strength. Such mechanical properties of soy-protein-containing nanofiber mats as Young’s modulus, yield stress, and maximum stress and strain at rupture were measured for different cross-linkers at different contents. Overall, higher contents of cross-linking agents in soy protein nanofiber mats resulted in nanofibers with higher strength which was accompanied by a less plastic behavior. Treatment with ionic cross-linkers resulted in nanofiber mats with higher Young’s modulus of the mats. Covalent bonds formed by aldehyde groups had a smaller effect on the mat strength. As cross-linked nanofibers were exposed to heat, the bonds formed between amino groups in the fibers were broken and they became less aggregated. The overall increase of about 50% in tensile strength as a result of thermal bonding under compression was observed. In addition, wet conglutination of soy protein/nylon 6 nanofiber mats for 24 h under 6 kPa pressure led to partial physical cross-linking of nanofibers and, consequently, to a 65% increase in Young’s modulus. Solution-blown soy protein/nylon 6 nanofiber mats were also subjected to aging in water for 1 h at 80 °C. An enhancement in the tensile strength of soy protein nanofiber mats was revealed after the exposure to water, as well as a slight plasticizing effect. DA - 2012/11/9/ PY - 2012/11/9/ DO - 10.1021/ie302359x VL - 51 IS - 46 SP - 15109-15121 J2 - Ind. Eng. Chem. Res. LA - en OP - SN - 0888-5885 1520-5045 UR - http://dx.doi.org/10.1021/ie302359x DB - Crossref ER - TY - JOUR TI - A macroscale model for simulating pressure drop and collection efficiency of pleated filters over time AU - Fotovati, S. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - Separation and Purification Technology AB - In this work, a computationally affordable macroscale model is developed to simulate the instantaneous collection efficiency and pressure drop of pleated depth filters. The numerical scheme presented here allows for the deposition of particles inside the fibrous fabric of a pleated filter, and accordingly varies its permeability and capture efficiency to simulate aging of the filter over time. This has been accomplished by developing a series of in-house subroutines that remarkably enhance the capabilities of the commercially available computational fluid dynamics code from ANSYS. This model is used to quantify the influence of pleat count, particle diameter, and flow velocity on the instantaneous performance of pleated filters with V-shaped pleats. Our results indicate that increasing the number of pleats reduces the rate of increase of a filter’s pressure drop and capture efficiency. Predictions of our model have been compared against available experimental data, and good agreement has been observed. DA - 2012/9// PY - 2012/9// DO - 10.1016/j.seppur.2012.07.009 VL - 98 SP - 344-355 J2 - Separation and Purification Technology LA - en OP - SN - 1383-5866 UR - http://dx.doi.org/10.1016/j.seppur.2012.07.009 DB - Crossref KW - Modeling filtration KW - Pleated filters KW - Dust-load simulation ER - TY - JOUR TI - Computation of mechanical anisotropy in thermally bonded bicomponent fibre nonwovens AU - Demirci, Emrah AU - Acar, Memiş AU - Pourdeyhimi, Behnam AU - Silberschmidt, Vadim V. T2 - Computational Materials Science AB - Having a unique microstructure composed of randomly-oriented polymer-based fibres, nonwovens exhibit complex deformation characteristics. The most prominent one is the mechanical anisotropy leading to their direction-dependent deformation behaviour. This paper focuses on mechanical anisotropy of thermally bonded bicomponent fibre nonwovens with polymer-based bicomponent core/sheath fibres. A relation between mechanical anisotropy of these nonwovens and random orientation of their fibres is developed in this study. Random orientation of individual fibres is quantified in terms of the orientation distribution function (ODF) in order to determine the material’s anisotropy. The ODF is obtained by analysing the data acquired with scanning electron microscopy or X-ray micro-computed tomography using digital image processing techniques based on the Hough transform. A numerical tool is developed to perform this analysis and determine the anisotropic parameters in order to define direction-dependency of the structure’s mechanical properties. Finally, anisotropic parameters of various nonwovens computed with the introduced numerical approach are compared with those obtained from tensile tests applied in machine and cross directions of nonwovens. DA - 2012/2// PY - 2012/2// DO - 10.1016/j.commatsci.2011.01.033 VL - 52 IS - 1 SP - 157-163 J2 - Computational Materials Science LA - en OP - SN - 0927-0256 UR - http://dx.doi.org/10.1016/j.commatsci.2011.01.033 DB - Crossref KW - Thermally bonded nonwoven KW - Bicomponent fibre KW - Orientation distribution function KW - Mechanical anisotropy KW - Digital image processing KW - Hough transform ER - TY - JOUR TI - Three-Dimensional Structural Characterization of Nonwoven Fabrics AU - Venu, Lalith B. Suragani AU - Shim, Eunkyoung AU - Anantharamaiah, Nagendra AU - Pourdeyhimi, Behnam T2 - MICROSCOPY AND MICROANALYSIS AB - Nonwoven materials are found in a gamut of critical applications. This is partly due to the fact that these structures can be produced at high speed and engineered to deliver unique functionality at low cost. The behavior of these materials is highly dependent on alignment of fibers within the structure. The ability to characterize and also to control the structure is important, but very challenging due to the complex nature of the structures. Thus, to date, focus has been placed mainly on two-dimensional analysis techniques for describing the behavior of nonwovens. This article demonstrates the utility of three-dimensional (3D) digital volumetric imaging technique for visualizing and characterizing a complex 3D class of nonwoven structures produced by hydroentanglement. DA - 2012/12// PY - 2012/12// DO - 10.1017/s143192761201375x VL - 18 IS - 6 SP - 1368-1379 SN - 1435-8115 KW - fibrous structures KW - three-dimensional (3D) visualization KW - nonwovens KW - hydroentangling KW - fiber orientation KW - solid volume fraction ER - TY - JOUR TI - Temperature and Exposure Dependence of Hybrid Organic-Inorganic Layer Formation by Sequential Vapor Infiltration into Polymer Fibers AU - Akyildiz, Halil I. AU - Padbury, Richard P. AU - Parsons, Gregory N. AU - Jur, Jesse S. T2 - LANGMUIR AB - The characteristic processing behavior for growth of a conformal nanoscale hybrid organic–inorganic modification to polyamide 6 (PA6) by sequential vapor infiltration (SVI) is demonstrated. The SVI process is a materials growth technique by which exposure of organometallic vapors to a polymeric material promotes the formation of a hybrid organic–inorganic modification at the near surface region of the polymer. This work investigates the SVI exposure temperature and cycling times of sequential exposures of trimethylaluminum (TMA) on PA6 fiber mats. The result of TMA exposure is the preferential subsurface organic–inorganic growth by diffusion into the polymer and reaction with the carbonyl in PA6. Mass gain, infrared spectroscopy, and transmission electron microscopy analysis indicate enhanced materials growth and uniformity at lower processing temperatures. The inverse relationship between mass gain and exposure temperature is explained by the formation of a hybrid layer that prevents the diffusion of TMA into the polymer to react with the PA6 upon subsequent exposure cycles. As few as 10 SVI exposure cycles are observed to saturate the growth, yielding a modified thickness of ∼75 nm and mass increase of ∼14 wt %. Removal of the inherent PA6 moisture content reduces the mass gain by ∼4 wt % at low temperature exposures. The ability to understand the characteristic growth process is critical for the development of the hybrid materials fabrication and modification techniques. DA - 2012/11/6/ PY - 2012/11/6/ DO - 10.1021/la302991c VL - 28 IS - 44 SP - 15697-15704 SN - 0743-7463 ER - TY - JOUR TI - Surface modifications of polypropylene with nonylphenol ethoxylates melt additives AU - Datla, V. AU - Shim, E. AU - Pourdeyhimi, B. T2 - POLYMER ENGINEERING AND SCIENCE AB - Abstract Nonylphenol ethoxylated (NPE) additives were melt blended in polypropylene (PP) films and characteristics of the modified films were investigated. It was found that melt blending of NPE additives improved hydrophilicity of PP films through additive surface segregation. Surface specific techniques, such as X‐ray photoelectron spectroscopy (XPS) and Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) were used to study surface compositions of samples modified with NPE additives at different aging time after extrusion. We found that surface enrichment of additives lead to hydrophilic surfaces. Hydrophilic chain length in NPE affected surface composition and hydrophilicity of NPE containing PP polymer. The effect of water immersion and aging were also reported. POLYM. ENG. SCI., 52:1920–1927, 2012. © 2012 Society of Plastics Engineers DA - 2012/9// PY - 2012/9// DO - 10.1002/pen.23153 VL - 52 IS - 9 SP - 1920-1927 SN - 1548-2634 ER - TY - JOUR TI - Release Profiles of Tricalcium Phosphate Nanoparticles from Poly(L-lactic acid) Electrospun Scaffolds with Single Component, Core-Sheath, or Porous Fiber Morphologies: Effects on hASC Viability and Osteogenic Differentiation AU - Asli, Mahsa Mohiti AU - Pourdeyhimi, Behnam AU - Loboa, Elizabeth G. T2 - MACROMOLECULAR BIOSCIENCE AB - Abstract Functional PLA scaffolds are created with single component, core–sheath, or porous fiber morphology and doped with TCP nanoparticles to study the release profiles for use in bone tissue engineering applications. Pharmacokinetic analyses are performed for the three different nanofibrous structures after doping with TCP. Results indicate that single component and porous fiber scaffolds exhibit an initial‐burst release profile whereas core–sheath fibers show a steady release. All scaffolds are then seeded with human adipose‐derived stem cells (hASC), which remain viable and continue proliferation on all nanofibrous morphologies for up to 21 d. Osteogenic differentiation of hASC and cell‐mediated calcium accretion are largest on porous fibers. magnified image DA - 2012/7// PY - 2012/7// DO - 10.1002/mabi.201100470 VL - 12 IS - 7 SP - 893-900 SN - 1616-5195 KW - biomaterials KW - controlled release scaffolds KW - human adipose derived stem cells KW - nanoparticles KW - osteogenesis ER - TY - JOUR TI - Dependence of the liquid absorption behavior of nonwovens on their material and structural characteristics: Modeling and experiments AU - Das, Dipayan AU - Pradhan, Arun Kumar AU - Pourdeyhimi, Behnam T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - Abstract Nonwovens are widely used as liquid absorbent products. Baby diapers, sanitary napkins, adult incontinence pads, oil sorbents, wet wipes, and wound dressings, to name a few, are excellent examples of the use of nonwovens as absorbent media. The performance of nonwoven absorbent media is determined by its liquid absorption behavior, which is characterized by the capacity of absorption and the rate of absorption. In this article, we report on the effects of the physical characteristics of the constituent fibers and the internal structure of the nonwovens on their liquid absorption behavior. A theoretical model of liquid absorption behavior of nonwovens was developed, and this model was verified with a set of experimental results obtained on real nonwoven materials. The nonwoven materials were prepared with polyester fibers with different cross‐sectional sizes and their liquid absorption properties were measured with the gravimetric absorbency testing system. We observed that the size of fiber cross sections and the porosity of the nonwovens played very important roles in determining their absorbent capacity and rate of absorption. The results of the experiments were discussed in light of the theoretical model. The theoretical results were found to be in good agreement with the experimental results. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 DA - 2012/11/5/ PY - 2012/11/5/ DO - 10.1002/app.36635 VL - 126 IS - 3 SP - 1053-1060 SN - 1097-4628 KW - absorption KW - fibers KW - modeling KW - nonwoven KW - structure ER - TY - JOUR TI - Templating Quantum Dot to Phase-Transformed Electrospun TiO2 Nanofibers for Enhanced Photo-Excited Electron Injection AU - Aykut, Yakup AU - Saquing, Carl D. AU - Pourdeyhimi, Behnam AU - Parsons, Gregory N. AU - Khan, Saad A. T2 - ACS APPLIED MATERIALS & INTERFACES AB - We report on the microstructural crystal phase transformation of electrospun TiO2 nanofibers generated via sol–gel electrospinning technique, and the incorporation of as-synthesized CdSe quantum dots (QDs) to different phases of TiO2 nanofibers (NFs) via bifunctional surface modification. The effect of different phases of TiO2 on photo-excited electron injection from CdSe QDs to TiO2 NFs, as measured by photoluminescence spectroscopy (PL) is also discussed. Nanofiber diameter and crystal structures are dramatically affected by different calcination temperatures due to removal of polymer carrier, conversion of ceramic precursor into ceramic nanofibers, and formation of different TiO2 phases in the fibers. At a low calcination temperature of 400 oC only anatase TiO2 nanofiber are obtained; with increasing calcination temperature (up to 500 oC) these anatase crystals became larger. Crystal transformation from the anatase to the rutile phase is observed above 500oC, with most of the crystals transforming into the rutile phase at 800oC. Bi-functional surface modification of calcined TiO2 nanofibers with 3-mercaptopropionic acid (3-MPA) is used to incorporate as-synthesized CdSe QD nanoparticles on to TiO2 nanofibers. Evidence of formation of CdSe/TiO2 composite nanofibers is obtained from elemental analysis using Energy Dispersive X-ray spectroscopy (EDS) and TEM microscopy that reveal templated quantum dots on TiO2 nanofibers. Photoluminescence emission intensities increase considerably with the addition of QDs to all TiO2 nanofiber samples, with fibers containing small amount of rutile crystals with anatase crystals showing the most enhanced effect. DA - 2012/8// PY - 2012/8// DO - 10.1021/am300524a VL - 4 IS - 8 SP - 3837-3845 SN - 1944-8252 KW - quantum dot KW - sol-gel electrospinning KW - nanofibers KW - photoluminescence ER - TY - JOUR TI - Numerical modelling of damage initiation in low-density 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 - Due to random orientation of fibres and presence of voids in their microstructure, low-density thermally bonded polymer-based nonwovens demonstrate complex processes of deformation and damage initiation and evolution. This paper aims to introduce a micro-scale discontinuous finite element model to simulate an onset of damage in low-density nonwovens. In the model, structural randomness of a nonwoven fabric was introduced in terms of orientation distribution function (ODF) obtained by an algorithm based on the Hough Transform. Fibres were represented in the model with truss elements with orientations defined according to the computed ODF. Another structural element of nonwovens – bond points – were modelled with shell elements having isotropic mechanical properties. The numerical scheme employed direct modelling of fibres at micro level, naturally introducing the presence of voids into the model and thus making it suitable for simulations of low-density nonwovens. The obtained results of FE simulations were compared with our data of tensile tests performed in principal directions until the onset of damage in the specimens. DA - 2012/11// PY - 2012/11// DO - 10.1016/j.commatsci.2012.05.038 VL - 64 SP - 112-115 SN - 1879-0801 KW - Nonwoven KW - Anisotropy KW - Finite element KW - Damage ER - TY - JOUR TI - Directed inorganic modification of bi-component polymer fibers by selective vapor reaction and atomic layer deposition AU - Gong, Bo AU - Spagnola, Joseph C. AU - Arvidson, Sara A. AU - Khan, Saad A. AU - Parsons, Gregory N. T2 - POLYMER AB - Abstract Nanocomposite organic/inorganic materials with spatially-controlled composition can be formed using vapor-phase atomic layer deposition (ALD) on bi-component polymer fibers. The ALD process promotes selective precursor infusion into the inner core of a core/shell polymer fiber, yielding nanoparticles encapsulated within the core. Likewise, choosing alternate precursors or reaction conditions yield particles or films on the outer polymer shell. In-situ infrared spectroscopy and transmission electron microscopy show that infusion yields selective dispersion of aluminum oxide in different polymer regions, forming fine nanoparticle dispersions or films. Selective inclusion of metal oxide materials during atomic layer deposition on polymers can create unique organic/inorganic composite structures for many advanced uses. DA - 2012/9/28/ PY - 2012/9/28/ DO - 10.1016/j.polymer.2012.08.018 VL - 53 IS - 21 SP - 4631-4636 SN - 1873-2291 KW - Atomic layer deposition KW - Bi-component fibers KW - Vapor infiltration ER - TY - JOUR TI - Generation of Functional Coatings on Hydrophobic Surfaces through Deposition of Denatured Proteins Followed by Grafting from Polymerization AU - Goli, Kiran K. AU - Rojas, Orlando J. AU - Oezcam, A. Evren AU - Genzer, Jan T2 - BIOMACROMOLECULES AB - Hydrophilic coatings were produced on flat hydrophobic substrates featuring n-octadecyltrichlorosilane (ODTS) and synthetic polypropylene (PP) nonwoven surfaces through the adsorption of denatured proteins. Specifically, physisorption from aqueous solutions of α-lactalbumin, lysozyme, fibrinogen, and two soy globulin proteins (glycinin and β-conglycinin) after chemical (urea) and thermal denaturation endowed the hydrophobic surfaces with amino and hydroxyl functionalities, yielding enhanced wettability. Proteins adsorbed strongly onto ODTS and PP through nonspecific interactions. The thickness of adsorbed heat-denatured proteins was adjusted by varying the pH, protein concentration in solution, and adsorption time. In addition, the stability of the immobilized protein layer was improved significantly after interfacial cross-linking with glutaraldehyde in the presence of sodium borohydride. The amino and hydroxyl groups present on the protein-modified surfaces served as reactive sites for the attachment of polymerization initiators from which polymer brushes were grown by surface-initiated atom-transfer radical polymerization of 2-hydroxyethyl methacrylate. Protein denaturation and adsorption as well as the grafting of polymeric brushes were characterized by circular dichroism, ellipsometry, contact angle, and Fourier transform infrared spectroscopy in the attenuated total reflection mode. DA - 2012/5// PY - 2012/5// DO - 10.1021/bm300075u VL - 13 IS - 5 SP - 1371-1382 SN - 1525-7797 ER - TY - JOUR TI - Drop impacts on electrospun nanofiber membranes AU - Sahu, R. P. AU - Sinha-Ray, S. AU - Yarin, A. L. AU - Pourdeyhimi, B. T2 - SOFT MATTER AB - This work reports a systematic study of drop impacts of polar and non-polar liquids onto different electrospun nanofiber membranes (of 8–10 μm thickness and pore sizes of 3–6 μm) with an increasing degree of hydrophobicity. The liquids studied were water, FC 7500 (Fluorinert fluid) and hexane. The nanofibers used were electrospun from polyacrylonitrile (PAN), nylon 6/6, polycaprolactone (PCL) and Teflon. It was found that for any liquid/fiber pair there exists a threshold impact velocity (∼1.5 to 3 m s−1) above which water penetrates membranes irrespective of their hydrophobicity. The other liquids (FC 7500 and hexane) penetrate the membranes even more easily. The low surface tension liquid, FC 7500, left the rear side of sufficiently thin membranes as a millipede-like system of tiny jets protruding through a number of pores. For such a high surface tension liquid as water, jets immediately merged into a single bigger jet, which formed secondary spherical drops due to capillary instability. No mechanical damage to the nanofiber mats after liquid perforation was observed. A theoretical estimate of the critical membrane thickness sufficient for complete viscous dissipation of the kinetic energy of penetrating liquid is given and corroborated by the experimental data. DA - 2012/// PY - 2012/// DO - 10.1039/c2sm06744g VL - 8 IS - 14 SP - 3957-3970 SN - 1744-683X ER - TY - JOUR TI - Polymers coalesced from their cyclodextrin inclusion complexes: What can they tell us about the morphology of melt-crystallized polymers? AU - Gurarslan, Alper AU - Joijode, Abhay S. AU - Tonelli, Alan E. T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Abstract Cyclodextrins (CDs) are cyclic polysaccharides with nano‐size, largely hydrophobic cavities, and exteriors covered with hydrophilic hydroxyl groups, making them water soluble. Threading and filling their cavities with polymer chains produces noncovalently bonded crystalline inclusion compounds (ICs). In this study, we formed fully covered, stoichiometric ICs between guest poly( L ‐lactic acid), poly(ε‐caprolactone), and nylon‐6 chains and host α‐CD. Coalesced samples of all three polymers were obtained after appropriately removing the stacked α‐CD host channels from their ICs. Distinct differential scanning calorimetriy (DSC) thermograms were observed for as‐received and coalesced samples, with the coalesced samples crystallizing faster at higher temperatures from their melts, and this distinction was maintained even after extensive, long‐time melt‐annealing (hours, days, and weeks). We believe this is due to the largely unentangled chains with extended conformations that are more densely packed in the initially coalesced samples. When small amounts (∼2 wt %) of the coalesced polymers are used as self‐nucleating agents for their as‐received samples, the resulting self‐nucleated samples show DSC thermograms similar to those of the neat coalesced polymers, including their long‐time stability to melt‐annealing. Coalesced polymers, whether neat or in samples they self‐nucleate, may conserve their organization in the melt (largely extended and unentangled chains) for long periods, because the process of entangling the many chains influenced by a single initially extended unentangled coalesced chain, after it randomly coils, is extremely sluggish. By contrast, in melt‐crystallized or solution‐cast samples, polymer chains generally become fully randomly coiled, interpenetrate, and entangle after being heated and held in their melts for comparatively much shorter times. For example, we have recently observed (DSC) that ultra high molecular weight, gel‐spun spectra polyethylene (PE) fibers ® did not conserve or retain any memory of their as‐spun and highly drawn semicrystalline morphology even after spending as little as 2 min in the melt. As a consequence of the comparison to the behavior of coalesced polymer melts, we believe that polyethylene chains in Spectra fibers ® must be at least intimately dispersed within their crystalline regions, and likely partially coiled and entangled in their noncrystalline regions, thereby facilitating their rapid transformation into a full entanglement network of randomly coiling chains in the melt. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 DA - 2012/6/15/ PY - 2012/6/15/ DO - 10.1002/polb.23074 VL - 50 IS - 12 SP - 813-823 SN - 0887-6266 KW - cyclodextrin KW - inclusion chemistry KW - morphology KW - solid-state structure KW - thermal stability ER - TY - JOUR TI - Stress-strain dependence for soy-protein nanofiber mats AU - Khansari, S. AU - Sinha-Ray, S. AU - Yarin, A. L. AU - Pourdeyhimi, B. T2 - JOURNAL OF APPLIED PHYSICS AB - Soy protein/nylon 6 monolithic and core-shell nanofibers were solution-blown and collected on a rotating drum as fiber mats. Tensile tests of rectangular strips of these mats revealed their stress-strain dependences. These dependences were linear at low strains which correspond to their elastic behavior. Then, a plastic-like nonlinearity sets in, which is followed by catastrophic rupture. Parameters such as Young’s modulus, yield stress, and specific strain energy were measured. The results were rationalized in the framework of the phenomenological elastic-plastic model, as well as a novel micromechanical model (the latter attributes plasticity to bond rapture between the individual overstressed fibers in the mat). Besides, the effects of stretching history, rate of stretching, and winding velocity of the collector drum on the strength-related parameters are studied. The results for soy protein/nylon 6 nanofiber mats are also compared to those for solution blown pure nylon 6 mats, which were produced and tested in the same way. DA - 2012/2/15/ PY - 2012/2/15/ DO - 10.1063/1.3682757 VL - 111 IS - 4 SP - SN - 0021-8979 ER - TY - JOUR TI - Influence of polymer type, composition, and interface on the structural and mechanical properties of core/sheath type bicomponent nonwoven fibers AU - Dasdemir, Mehmet AU - Maze, Benoit AU - Anantharamaiah, Nagendra AU - Pourdeyhimi, Behnam T2 - JOURNAL OF MATERIALS SCIENCE DA - 2012/8// PY - 2012/8// DO - 10.1007/s10853-012-6499-7 VL - 47 IS - 16 SP - 5955-5969 SN - 0022-2461 ER - TY - JOUR TI - Modification of Melt-Spun Isotactic Polypropylene and Poly(lactic acid) Bicomponent Filaments with a Premade Block Copolymer AU - Arvidson, Sara A. AU - Roskov, Kristen E. AU - Pate, Jaimin J. AU - Spontak, Richard J. AU - Khan, Saad A. AU - Gorga, Russell E. T2 - MACROMOLECULES AB - While numerous studies have investigated the effect of adding a block copolymer as a macromolecular surfactant to immiscible polymer blends, no such efforts have sought to alter the properties of melt-spun bicomponent core–sheath filaments with a nonreactive compatibilizing agent. In this study, we examine the effect of adding poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) triblock copolymer to core–sheath filaments consisting of isotactic polypropylene (iPP) and poly(lactic acid) (PLA). Incorporation of the copolymer into blends of iPP/PLA is observed to reduce the size scale of phase separation. Interfacial slip between molten iPP and PLA layers is evaluated by rheology under steady-shear conditions. Addition of SEBS to the PLA sheath during filament formation reduces the tendency of PLA sheaths to crack prior to iPP core failure during tensile testing. In reversed filament configurations, the copolymer does not hinder the development of molecular orientation, related to fiber strength, during fiber spinning. Electron microscopy reveals that the copolymer molecules form unique, highly nonequilibrium morphologies under the spinning conditions employed here. DA - 2012/1/24/ PY - 2012/1/24/ DO - 10.1021/ma202246h VL - 45 IS - 2 SP - 913-925 SN - 1520-5835 ER - TY - JOUR TI - Selective Permeation of Cross-Linked Polyelectrolyte and Polyelectrolyte-Filled Nonwoven Membranes AU - Jung, Kyung-Hye AU - Pourdeyhimi, Behnam AU - Zhang, Xiangwu T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - Abstract Selective permeation, driven by ionic attraction, is one of the most important properties of polyelectrolyte membranes. In this study, selective permeation behaviors of different polyelectrolytes, poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (PAMPS), poly(styrene sulfonic acid) (PSS), and poly(methacrylic acid) (PMA), were studied via solution‐diffusion mechanism. Among these three polyelectrolytes, PSS membranes showed the highest permeabilities for both water and dimethyl methylphophonate vapors due to their high diffusion coefficients caused by the high flexibility of PSS chains. It was also found that the cross‐linking of polymer chains increased membrane permeabilities by weakening the physical network formed by ionic attraction. However, the type and cross‐linking of polyelectrolytes did not have significant effect on the membrane selectivities. Nonwoven fabric was employed to control the selective permeation of polyelectrolyte membranes. It was found that filling the nonwoven fabric with polyelectrolytes led to composite membranes with reduced permeabilities and increased selectivities. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011. DA - 2012/1/5/ PY - 2012/1/5/ DO - 10.1002/app.34453 VL - 123 IS - 1 SP - 227-233 SN - 0021-8995 KW - membranes KW - crosslinking KW - diffusion ER - TY - JOUR TI - Structure, molecular orientation, and resultant mechanical properties in core/sheath poly(lactic acid)/polypropylene composites AU - Arvidson, Sara A. AU - Wong, Ka C. AU - Gorga, Russell E. AU - Khan, Saad A. T2 - POLYMER AB - We study the coaxial spinning of poly(lactic acid) (PLA) with polypropylene (PP) in a core/sheath configuration. PPcore/PLAsheath and PLAcore/PPsheath fibers maintain the high breaking strength that PP and PLA exhibit individually, showing marked improvement in strength over previous reports of PP/PLA blend fibers. Crystalline morphologies are greatly affected by the location within the fiber (i.e., core, sheath, or spun individually), and hence, co-spinning provides a route to tailor the morphology and fiber diameter beyond that available with single component fibers. A new approach to estimate molecular orientation of core sheath fibers based on the tensile response of the fiber is developed, and indicates that co-spinning PP with PLA results in a synergistic effect with increases in the molecular orientation above that which is possible with spinning either PP or PLA individually. DA - 2012/2// PY - 2012/2// DO - 10.1016/j.polymer.2011.12.042 VL - 53 IS - 3 SP - 791-800 SN - 0032-3861 KW - Polypropylene KW - Poly(lactic acid) KW - Core/sheath fiber ER -