## 6 Melt Electrospun Nanocomposites
Nanoclays are also widely employed to improve the properties of the matrix polymer. Fibrous nanocomposites based on nylon 6 (PA6) and montmorillonite (MMT) have been prepared by melt electrospinningning [156]. The phyllosilicate MMT, when added in the range of 1-10 wt.% into PA6, leads to an increase in the Young's modulus of a single melt electrospun fiber by a factor of 2 relative to the fibers of the same diameter prepared from the pure polyamide. A good dispersion of MMT into the polymer media is mandatory, hence melt processing is used to prepare the nanocomposite with desired dispersion state prior to melt electrospinningning. It was reported by [PERSON] et al. [156] that an increase in the MMT concentration leads to an increase in the number of charge carriers, which mobility increases with temperature. Both factors lead to an increase in the electrical conductivity of the melt to 10\({}^{-6}\) S cm\({}^{-1}\) for a MMT content of 3 wt.%, which represents a factor of 4 compared to the initial polymer. Nevertheless, viscosity also increased and therefore thicker fibers were usually obtained (e.g., diameters of 8.1 \(\upmu\)m and 12 \(\upmu\)m were determined when the MMT increased from 0 to 3 wt.%, respectively). Control of viscosity by increasing the processing temperature was not feasible due to polymer degradation evidences. Fibers showed also an increased roughness surface when the MMT was increased. Hyperthermia is an effective method for cancer treatment that can be applied by direct injection of magnetic particles into tumour tissues. Nevertheless, it is also necessary to use a biopolymer as a support since the direct injection of particles presents some disadvantages like leakage from the tumour site into the body. Composite nanofiber membranes could be prepared and then be attached to the surface of tumour tissues [157; 158]. In this regard, direct in situ electrospinningning onto the surface of the tumour tissue may be a suitable method to prevent the shedding of the composite fiber membrane and increase also the fitting of the composite fiber to the tumour [159]. By using a homemade self-powered portable melt electrospinningning apparatus (see Figure 9 for the detailed process), a PCL/Fe\({}_{3}\)O\({}_{4}\) membrane constituted by fibers with uniform diameter around 4-17 \(\upmu\)m could be fabricated [160]. Fe\({}_{3}\)O\({}_{4}\) magnetic nanoparticles affected the viscosity and conductivity of the melt, which in turn affected the electrospinningning process. A small number of nanoparticles provided a stable spinning process with smooth and well-distributed fibers, being possible to achieve and control a 5 \(\upmu\)m fiber diameter at a spinning distance of only 5 cm. High nanoparticle content caused an increase in this fiber diameter up to 15 \(\upmu\)m and a gradual roughing of the fiber surface. In vitro hyperthermia tests demonstrated that these magnetic fiber membrane composites produced by means of hand-held melt electrospinninging devices had a high potential for magnetic hyperthermia treatments. In addition, this portable melt electrospinninging device may also be easily extended to wound dressing and haemostasis using nanocomposites with excellent heating efficiency and thermal cycling characteristics. In bone tissue engineering applications, ideal pore sizes have been reported to range between 100 and 400 \(\upmu\)m [161], values that cannot be obtained by a simple solution electrospinningning [162]. A novel PCL/nHAp nanocomposite fibrous scaffold has been developed by [PERSON] et al. [163] by means of direct melt-electrospinning writing. Figure 10 shows a scheme of this process, which is able rendering continuous orderly stacked fibers according to a 0-90\({}^{\circ}\) pattern. and rough fibers after the incorporation of nHAp. This addition increased significantly the roughness of the PCL fibers and also their diameters (e.g., from 10.79 \(\upmu\)m to 16.84 and 20.46 \(\upmu\)m for 3 and 7 wt.% of nHAp, respectively).