The International Istanbul Textile Congress 2013 May 30th to June 1th 2013, Istanbul, Turkey 1 INVESTIGATION OF POLYACRYLONITRILE/CNT COMPOSITE NANOFIBERS PROPERTIES AS A FUNCTION OF CNT INDIVIDUAL DISPERSION CONDITIONS A. HAJI 1 , K. NASOURI 2 , A.M. SHOUSHTARI 2 , A. KAFLOU 3 1 Department of Textile Engineering, Birjand Branch, Islamic Azad University, Birjand, Iran. 2 Department of Textile Engineering, AmirKabir University of Technology, Tehran, Iran. 3 Department of Advanced Materials and Renewable Energy, Institute for Iranian Research Organization for Science and Technology, Tehran, Iran. Corresponding author: ahaji@iaubir.ac.ir Abstract: The dispersion stability behavior of single walled carbon nanotubes (SWCNTs) has important effects on various properties of SWCNT/polymer composite nanofibers. The relationship of the dispersion conditions with morphological and mechanical characteristics of SWCNT / polyacrylonitrile (PAN) / polyvinylpyrrolidone (PVP) composite nanofibers have been examined. The uniform, stable dispersion and well oriented SWCNT within the PAN matrix were achieved through using PVP as dispersing agent. The SEM and TEM analyses of the nanofibers revealed that the deformation in the nanofiber structures increases with increasing SWCNT concentration. Our data indicate that with increasing the amount of SWCNT (from 0 to 2 wt %), the average nanofiber diameter was increased from 163±19 nm to 307±34 nm. Tensile results showed that only 2 wt % SWCNT loading to the electrospun composite nanofibers gave rise to 10-fold and 3- fold increase in the tensile modulus and tenacity of nanofiber layers, respectively. Essentially, high mechanical properties and uniform morphology of the composite nanofibers were found at SWCNT concentration of ~2 wt % due to their stable and individual dispersion. Keywords: Carbon nanotube, Electrospinning, Composite nanofibers, Morphology, Mechanical Properties 1. Introduction Composites with nanoparticle are considered as materials that have the propensity to show amazing mechanical, electrical and thermal properties due to the interaction between the matrix and nanoparticle. These composites were reported to have the high strength and also good electrical conductivity at comparatively low carbon nanotubes (CNTs) loading. CNTs are classified in two general types, namely single-walled nanotubes (SWCNTs) and multi-walled nanotubes (MWCNTs). SWCNTs extraordinary mechanical properties due to carbon-carbon sp 2 bonds and cylinder structure present comparing to many other different nanoparticles and other forms of carbon [1-3]. Polymeric nanocomposites reinforced with SWCNTs are believed to have many potential engineering applications ranging from ultra-strong materials, lithium-ion batteries, electromagnetic interference shielding devices, gas sensors, and biosensors [4]. The various applications of SWCNT/polymer composite materials considerably depend on the individual dispersion and alignment of SWCNTs in the matrix, which is considered a very difficult job to be done. The difficulty in preparing well dispersed SWCNT composite solutions has been related to their higher specific surface area and consequently, possessing very stronger van der Waals interactions comparing to MWCNT solutions [5]. Therefore, the important challenges in electrospinning process of SWCNT/polymer nanofibers lie in preparing the uniform dispersion and oriented SWCNT within the polymer matrix structures. Non-chemical and chemical methods have been presented for preparing well dispersed SWCNT in the polymer solutions. The chemical methods presented by researchers mainly based on SWCNT oxidation [6], and situ polymerization [7]. The effective non-chemical dispersions have been described by using surfactants or amphiphilic polymers, which can be adsorbed onto the hydrophobic SWCNT surfaces, such as sodium dodecyl sulfate (SDS) [8], polyvinylpyrrolidone (PVP) and polystyrene sulfonate (PSS) [9], and natural polysaccharide Gum Arabic [10]. However, the non-chemical methods have been preferred because, chemical approaches mainly give rise to structure deterioration, non friendly environmental process, and consuming higher amounts of chemicals. The fabrication of SWCNT reinforced nanofibers is a promising technique to advance composite materials. Among the various methods of producing SWCNT/polymer composite nanofibers, electrospinning is a novel and efficient tool for their fabrication [11-13]. In this work, SWCNTs were dispersed by a non-chemical method and then embedded and aligned in polyacrylonitrile (PAN) / PVP nanofibers by electrospinning process. Finally, the effects of SWCNTs dispersion behavior on the morphological and mechanical properties of the electrospun PAN/PVP composite nanofibers were investigated.