There has been a considerable amount of work in the literature on the use of polymer nanofibers (NFs) and NF composites in various applications such as, electronics, automobile, energy storage, military, aerospace, membrane science, filtration, drug delivery systems, tissue engineering, and biosensors to mention some [1-10]. Several processing methods exist for the production of NFs such as electrospinning, hydrothermal synthesis, template synthesis, phase separation, self-assembly, shear spinning, and other spinning methods (wet, dry, and melt spinning) . Electrospinning could be considered a simple and low cost process given that only a syringe and a high voltage source are needed for lab scale production, though the process itself presents many limitations such as the need of high electric fields and typically the need of a dielectric solution besides the intrinsic suitable vapor pressure, viscosity, and surface tension to promote optimum fiber formation. These limitations render electrospinning as a complex and costly method for industrial potential. In general, electrospinning has been a widely used method to produce NFs at a lab scale. In the case of melt-blown process, which is a traditional melt spinning process, micro-fibers can be easily produced but in order to produce NFs, higher speeds of heated air are necessary which makes this process impracticable especially for industrial production. Forcespinning® (FS) technology (developed by Lozano et al.), as well as similar centrifugal spinning methods have the opportunity to offer a high production rate of NFs with low cost and a broader choice of materials given the absence of electric fields [11-21]. Several systems have been recently produced either from solution or melt, such as polyamide, polyethylene oxide, polylactic acid, polycaprolactone , polypropylene , ultra-high molecular weight polyethylene, (2,5-bis(2′-ethyl-hexyl)−1,4-phenylenevinylene) , poly(3-hexylthiophene (P3HT), Teflon®AF , cellulose, poly(vinylidene fluoride) , and indium-tin oxide  to mention some. All of the above have produced average fiber diameters in the nano or submicron range.
In this work, we use the FS method to prepare poly(vinyl) butyral (PVB) NFs and carbon nanotube (CNT)/PVB NF composites for potential applications such as electronic technology that require the use of polymer/ceramic nanocomposites with enhanced thermal conductivity, low coefficient of thermal expansion, and improved dielectric breakdown . PVB is a semi-crystalline polyester with low cost, good recyclability, clarity, toughness, flexibility, and excellent adhesion properties [23-25]. In addition, PVB is a good solute in alcohols and aromatic solvents which makes PVB solutions nontoxic and desirable for use in industry. It is mainly used as adhesive (binder) and matrix in ceramic based composites due to its compatibility and processability [26-28]. The high adhesion properties of PVB make it a good candidate for use in nanocomposites where the adhesion between the matrix and filler is crucial in determining the properties and performance of the nanocomposites [26-29]. For example, PVB was used as a matrix for boron nitride nanotubes (BNNT) to fabricate composites for electronic applications. The results showed a significant improvement in the thermal conductivity and dielectric properties of the composites. The dielectrical breakdown of the PVB/BNNT was also improved . Although an extensive work has been reported on the processing and characterization of PVB, a limited number of studies are available on the production of PVB NFs [23, 24]. PVB has been used as a polymer matrix for CNT to fabricate nanocomposites with enhanced electrical and thermal properties [30-32]. CNT reinforced polymer composites had lately been a source of intense research given their attractive properties such as high aspect ratio of CNT, good electrical conductivity, good mechanical strength, and high thermal stability [33-38]. CNT reinforced PVB composites have also been produced to enhance hardness, coefficient of friction, and scratch resistance of PVB .
A recent study utilized a surface-draw method to produce CNT reinforced PVB fiber composites, where the CNT content was varied from 0 to 80 wt%. The diameter of the developed fibers varied from 10 to 100 µm. Compared to pure PVB fibers, it was found that the CNT/PVB composites with 7.4 wt% of CNT concentration showed 127% increase in the tensile strength when compared to pure PVB fibers . However, the diameter of the composite fibers is higher than 10 µm. In this work, PVB and CNT/PVB NF composites are fabricated by using the FS method and the process variable effects on the mechanical and electrical properties of PVB NF matrix were systematically investigated. The main thrust of the article is the large-scale approach for the production of high tensile strength CNT reinforced PVB NFs.