# Mechanical and Dielectric Properties of Aligned Electrospun Fibers
## 3 Mechanical and Dielectric Properties of Nanofibers
### Drawing Process
#### 3.1.2 Other Electrospun Nanofibers  
In this session, [PERSON] et al. (2009) reported the mechanical property of a PAN-derived carbon nanofiber composite and the effect of molecular orientation along the fiber direction [154]. The study placed electrospun carbonized PAN nanofibers on a stacking sequence of 0, 45, \(-\)45, and 45 to create a laminate of ten plies. The tensile testing of PAN-derived carbon nanofiber composites revealed that they possess a high elastic modulus due to stabilization at a high temperature (280 \({}^{\circ}\)C), for 1 h, in an oxygen atmosphere. Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and differential scanning calorimetry (DSC) analyses confirmed that the nanofibers were crystalline and had good mechanical and thermal properties. Thinner nanofibers have larger surface-area-to-volume ratios. Therefore, thinner fibers have better mechanical integrity between the matrix and the surface of the reinforcing agent for effective load transfer in composites. [PERSON] et al. (2010) proved that as the PCL fiber diameter reduces, the tensile strength and modulus increase [103]. Figure 14a shows the tensile strength and modulus versus fiber diameter. For fiber diameters greater than 2 um, both tensile modulus and tensile strength appear not to change with diameter. The degree of crystallinity increases gradually as the PCL fiber diameter is reduced as shown in Figure 14b. As for polymers, in general, an increase in the degree of crystallinity increases the density, stiffness, strength, and toughness [155]. [PERSON] et al. (2016) showed that with the addition of conductive filler materials, the diameter of fibers reduced due to increasing composition of PVP/cellulose nanocrystal (CNC)/silver particle [156]. The addition of CNC increased the tensile strength.  
Figure 14: _Cont._  
The mechanical properties of different nanofibers are shown in Table 2. According to [PERSON] et al. (2015), the mechanical strength of various combinations of polylactic acid (PLA) and PCL mats was reported to be enhanced after thermal treatment at 60 \({}^{\circ}\)C. The melting of PCL enabled the sealing of the fibers, thus enhancing the mechanical properties of mats [157]. [PERSON] et al. (2004) reported an increase in modulus of silk/PEO fibers from as-spun to methanol-treated and to water-extracted fibers [158]. The mechanical properties of single fibers were characterized by AFM nanoindentation. [PERSON] et al. (2005) studied tensile property, using an approach that uses an atomic force microscope tip to stretch a single electrospun PEO nanofiber. The elastic modulus of PEO nanofiber was found to be 45 MPa [159]. [PERSON] et al. (2012) demonstrated characterization of mechanical properties of ultra-thin electrospun polymer fibers. Electrospun techophilic, tecoflex, nylon 6, PVP, and PEOX fibers were captured directly on the testing device, stretched at controlled rates, and deflected with forces created by different velocities of streams of air [160].