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Evaluation of electrospun nanofiber pore structure parameters
Akbar Khodaparast Haghi,Mohammad Ziabari,Vahid Mottaghitalab 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4
Nanofibers produced by electrospinning method are widely used for drug delivery, as tissue scaffolding materials and filtration purposes where specific pore characteristics are required. For continued growth in these areas, it is critical that the nanofibers be properly designed for these applications to prevent failure. Most of the current methods only provide an indirect way of determining pore structure parameters and contain inherent disadvantages. In this study, we developed a novel image analysis method for measuring pore characteristics of electrospun nanofiber webs. Five electrospun webs with different pore characteristics were analyzed by this method. The method is direct, very fast, and presents valuable and comprehensive information regarding pore structure parameters of the webs. Two sets of simulated images were generated to study the effects of web density, fiber diameter and its variations on pore characteristics. The results indicated that web density and fiber diameter significantly influence the pore characteristics, whereas the effect of fiber diameter variations was insignificant.
Distance transform algorithm for measuring nanofiber diameter
Akbar Khodaparast Haghi,Mohammad Ziabari,Vahid Mottaghitalab 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4
This paper describes a new distance transform method used for measuring fiber diameter in electrospun nanofiber webs. In this algorithm, the effect of intersection is eliminated, which brings more accuracy to the measurement. The method is tested by a series of simulated images with known characteristics as well as some real webs obtained from electrospinning of PVA. Our method is compared with the distance transform method. The results obtained by our method were significantly better than the distance transform, indicating that the new method could successfully be used to measure electrospun fiber diameter
Simulated image of electrospun nonwoven web of PVA and corresponding nanofiber diameter distribution
Akbar Khodaparast Haghi,Mohammad Ziabari,Vahid Mottaghitalab 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4
Fiber diameter is the most important characteristic in electrospun nonwoven webs. Understanding how it is influenced by the electrospinning parameters is essential to produce webs with desired characteristics. In this contribution, Direct Tracking method for measuring electrospun fiber diameter is described. To evaluate the accuracy of the technique, a simulation algorithm for generating webs with known characteristics was employed. To verify the applicability of the method on real samples, an electrospun polyvinyl alcohol (PVA) mat, as a representative of real webs, was used. Since the Direct Tracking method uses a binary image as its input, local thresholding was applied to segment the SEM micrograph of the electrospun web. The results indicate that the method could be used successfully for determining fiber diameter in electrospun nonwoven webs.
The electroless plating of Cu-Ni-P alloy onto cotton fabrics
Akbar Khodaparast Haghi,Arezoo Afzali,Vahid Mottaghitalab,Mahmood Saberi Motlagh 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4
The objective of this study is to apply the electroless plating of Cu-Ni-P alloy on cotton fabrics to the preparation of conductive fabrics. The alloy composed of infinit small amount of nickel and phosphorus particle originated from sodium hypophosphite and nickel sulphate respectively as reducing agent and hypophosphite oxidation accelerator. Electroless plating of Cu-Ni-P alloy on cotton fabrics and effect of plating on the physical and mechanical properties of alloy coated fabrics as well as electromagnetic interference (EMI) shielding effectiveness were reported in detail. In this research highly washing and abrasion durable conductive fabrics obtained with supreme shielding effectiveness.
A numerical study on drying of porous media
Akbar Khodaparast Haghi,Nima Amanifard 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.2
In this study, two-dimensional conjugate heat and mass transfer in porous body and drying air during the drying process were numerically investigated by finite volume (FV) method, which guarantees the conservation of mass, momentum and the energy during the numerical solution. The full NS-equations (including buoyancy terms), energy equation and concentration equation are considered for external flow and for porous field coupled energy and moisture transfer equations are used. The numerically captured curve shows the same behavior of the drying process. Drying flow velocity shows proportional effect on moisture removal rate with a factor between 1/4 and 1/5 in Reynolds range of 50 to 1,000. Also, buoyancy forces have an effect on flow streamlines, the distribution of vapor concentration, moisture profile, and considerably increase drying rate. This increment was investigated in Reynolds number range of 50 to 1,000, and its minimum value was found in a Reynolds number of 1,000, which was about 15 percent.
A new approach for optimization of electrospun nanofiber formation process
Akbar Khodaparast Haghi,Mohammad Ziabari,Vahid Mottaghitalab 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.1
Precise control of fiber diameter during electrospinning is very crucial for many applications. A systematic and quantitative study on the effects of processing variables enables us to control the properties of electrospun nanofibers. In this contribution, response surface methodology (RSM) was employed to quantitatively investigate the simultaneous effects of four of the most important parameters, namely solution concentration (C), spinning distance (d),applied voltage (V) and volume flow rate (Q), on mean fiber diameter (MFD) as well as standard deviation of fiber diameter (StdFD) in electrospinning of polyvinyl alcohol (PVA) nanofibers.
A study on the effects of laminating temperature on the polymeric nanofiber web
Akbar Khodaparast Haghi,Mohammad Kanafchian,Masoomeh Valizadeh 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2
The purpose of this study is to consider the influence of laminating temperature on nanofiber/laminate properties. Hot-press laminating was carried out at five different temperatures and nanofiber web morphology was observed under an optical microscope. Also, air permeability experiments were performed to examine the effect of laminating temperature on breathability of multilayer fabric. Optical microscope images showed that the nanofiber web began to damage when laminating temperature was selected above the melting point of adhesive layer. Air permeability decreased with increasing laminating temperature. It is also observed that the adhesive force between layers was increased by increasing laminating temperature.
Mohammad Kanafchian,Akbar Khodaparast Haghi,Masoomeh Valizadeh 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.3
Electrospun nanofiber web has many potential applications due to its large specific area, very small pore size and high porosity. However, the mechanical properties of nanofiber web are very poor for use in textile application. To remedy this defect, the laminating process could accomplish in order to protect nanofiber web versus mechanical stresses. In this paper, direct tracking method as an image analysis based technique for measuring electrospun nanofiber diameter has been presented. The usefulness of the method for electrospun nanofiber diameter measurement is discussed. Such automated measurement of nanofiber diameter can be used to obtain better laminated webs.
Fabrication of nanostructured and multicompartmental fabrics based on electrospun nanofibers
Mohammad Kanafchian,Akbar Khodaparast Haghi,Masoomeh Valizadeh 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.3
The fabrication of novel multilayer electrospun nanofiber web is demonstrated. Under optimized processing conditions, the interface between these webs can be sustained for long time, yielding layers with distinct compartments. Simultaneous control over internal fiber architecture makes these multilayer nano-webs potential candidates for applications such as clothing and industrial filters.
A study on electrospinning of polyacrylonitrile nanofibers
Vahid Mottaghitalab,Akbar Khodaparast Haghi 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1
Aligned and molecularly oriented Polyacrylonitrile (PAN) nanofibers were prepared using a non-conventional approach. Various take up velocity of rotating drum was examined for increasing of productivity, alignment and mechanical properties of nanofibers. Impressive techniques like Raman spectroscopy were utilized for characterization of nanofibers.