Solution Electrospinning of Nylon/Ferrite Nanofibers
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Solution Electrospinning of Nylon/Ferrite Nanofibers Autumn Dhanote, Samuel C. Ugbolue, Steven B. Warner, Prabir K. Patra, Phaneshwar Katangur, Shamal K. Mhetre. Department of Textile Science, University of Massachusetts Dartmouth, 285-Old Westport road, North Dartmouth, MA 02747, USA. ABSTRACT With an average diameter of 80-200 nm, nylon fibers embedded with ferrite nanoparticles were electrospun using a point to plate geometry. The nickel-ferrite particles with a diameter range of 20-30 nm were used to prepare the composite electrospun nanofibers. The ferrite nanoparticles were dispersed in the polymer solution using a surfactant dodecyl benzene sulfonic acid (DBSA). Ultrasonication was used to dissolve nylon-6 into the formic acid/particle dispersion. Electrospinning of virgin polymer solution and particle filled polymer system was carried out with polymer concentration of 15% w/v. The particle loading was 3%w/w. SEM of the particle filled fibers show some bead formations and a diameter distribution of about 80-200 nm. The DSC analyses of the neat nylon polymer fibers and ferrite filled nanofibers show an increase in glass transition temperature from 55°C to 72°C. The melting temperature showed a decrease from 226°C to 201°C. The TEM images show the presence and some alignment of particles in the polymer. The electron diffraction pattern of ferrite nanoparticles confirms its crystalline nature. INTRODUCTION Electrospinning has been recognized as an efficient technique for the fabrication of polymer nanofibers. Various polymers have been successfully eletrospun into ultrafine fibers [1]. The driving forces in the electrospinning are electrical forces on the free charges due to surface or inside polymeric liquid. According to Reneker and Chun [2], the free charges in the liquid polymer, move in response to the electric field and transfer a force to the polymer liquid. The principle is to use an electric field to draw a positively charged polymer solution from an orifice to collector. In this process a polymer solution or melt is typically held by the surface tension at the end of the capillary tube and subjected to a large electric field, i.e. on the order of 1 kV/cm. Charge is induced in the liquid by electric field. In the process of electrospinning, the phenomenon of bending instability results in elongation of electrospinning jet up to 100,000 times in a short distance and in less than one second [3]. This extremely large effective draw ratio will likely align anisotropic nanofillers, such as dispersed layered clay silicates or carbon nanotubes, as well as extend polymer chain conformations and influence the formation and structure of polymer crystallites [4]. The superiority of the properties of the fiber reinforced composites results from the fiber continuity and alignment [5]. If the particulate fillers can be aligned to form strings or columns they also could result in better property enhancements. Ilhan Aksay [6] has reported the alignment of particles in the presence of electric field. Although i
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