The Ultraviolet-Visible absorption spectra of PEO/PVDF blend and the blend loaded with 0.05 and 0.1 Wt% of SWCNTs in the range of 200 - 2000 nm at room temperature are shown in Figure 1. All UV-Vis curves are characterized by exponentially decay tail at lower energy due to localized states in the optical energy band gap and also indicating presence of amorphousregion of the samples. The origin of this band tailing is still a matter of conjecture but according to Dow and Redfield [13] .

It is observed in these spectra that each spectrum exhibit prominent peak at »254 nm due to n → π* (R- band) ‎electronic transitions. Moreover, there are no absorption bands on the ‎visible region for all samples since the films are transparent [14] .

The absorption coefficient (α) near the edge can be directly determined from the absorbance results using the following formula [15] :

where d is the thickness of the sample and A is the absorbance; where I_o and I are the in-

tensity of photon striking and emerging from the sample, respectively.

The plot of absorption coefficient (α) as a function for the samples is shown in Figure 2. The plot exhibit different slopes indicating the probability of the presence of different transitions in nanocomposite samples. The falling in the edges at lower photon energy region indicating the lack of long range order andirregular fluctuations of internal fields associated with disorder of the structure in the prepared samples. The absorptionedge for all samples is increases with increase SWCNTs content.

The extinction coefficient (k) is estimated from the equation [16] :

where is the wavelength of incident photon. The plot of the extinction coefficient (k) as a function of is shown in Figure 3. All spectrum show an increases of k with increase in attributed to the probability of electron transfer across the mobility rises with photon energy.

According to Tauc et al. [17] , three distinct regions are observed in the absorption spectrum. The first is the

absorption tail related to defects and impurities. Other one is exponential edge region is originates from the disorder in the structure of the material. The last is high absorption region which determines the optical band energy gap. In second region, absorption coefficient lies in the range between 10² and 10⁴ cm⁻¹. This follows Urbach equation [18] :

where is constant and is the width of the tail of localized states in the band gap. The inset of Figure 2 shows the relation between lnα versus hυ. The straight line suggest that the absorption follows the quadratic relation for inter band transition and hence satisfies the Urbach rule. The values of band tail which estimated from the slopes of these lines are 5.18, 4.48 and 4.06 eV for the blend, 0.05 and 0.1 Wt% of SWCNTs, respectively. The values of is decreases with increase of SWCNTs suggesting the decrease in the disorder in the prepared samples.

The optical band gap (E_g) has been determined from absorption coefficient data as a function of (hυ) by using the relation [19] :

where c is constant and E_g is the optical band gap of the sample. The variation of (αhν)² with photon energy (hυ) is shown in Figure 4. The values of indirect band gap (E_g) have been calculated by taking the intercept on the x-axis. It is evident from the figure that the values of optical band gap (E_g) decreases with increases SWCNTs concentration from 5.18 to 4.87 eV with increasing of SWCNTs content. The decrease in optical band gap E_g indicates an increase in the density of defect states. The decrease in optical band gap could also be discussed on the basis of density of state model proposed by Mott and Davis [20] [21] . The films contain a high concentration of unsaturated bonds or defects are responsible for the presence of localized states in amorphous band gap.‎ This indicates that there are charge transfer complexes arose between the polymer blend ‎and SWCNTs.

Figure 5 shows Raman spectra for pristine PEO, PVDF and SWCNTs in the range from 400 to 3200 nm at room temperature. The main characteristic bands of raw SWCNTs are observed at 1590 cm⁻¹ (G-band) and 1430 cm⁻¹ (D-band). The G-band is an intrinsic feature of carbon nanotubes that is related to vibrations in all sp carbon materials. The most important aspect of the G-band is the characteristic Raman line shape. The first band attributed to graphite is present in Raman shift for SWCNTs bundles as the band at 1580 cm⁻¹ assigned to G band in-plane vibration of the C-C bond. The G band is a tangential shear mode of carbon atoms that corresponds to the stretching mode in the graphite plane. The other band of SWCNTs bundle at 1341 cm⁻¹ assigned to D band activated by the presence of disorder in carbon systems. The Raman spectrum also exhibits a band at 2682 cm⁻¹ called the G″ band and attributed to the overtone of the D band. Some Raman bands are present located at 2888 and 2980 cm⁻¹ called G′-band. The frequency of these bands is close to twice that of the D band [22] -[24] .

For PEO, the band is observed at 1486 cm⁻¹ can be attributed to the in-phase bending for CH₂ group. This mode is active in Raman spectrum and not active in infrared spectrum. The bands observed at 1255 and 1239 cm⁻¹ are assigned to the out-of-phase twisting for CH group, the band at cm⁻¹ is corresponding to stretching mode of C-O group and the band at 1255 cm⁻¹ may be arises from disordered or amorphous portions of the polymer chain. The band at 840 cm⁻¹ is due to hydroxyl (OH) groups in PEO [25] .

The Raman shiftsof pure PVDF depicts that the crystal phase is α-phase or form II characterized by chain conformation. The PVDF vibration bands at 480 and 611 cm⁻¹. These modes are mainly due to CF₂ vibrations. The bands at 513 cm⁻¹ attributed to CF₂ bending vibration and higher intensity band at 840 cm⁻¹ due to out of phase combination of CH₂ rocking and CF₂ stretching mode [26] [27] . These bands are is mainly β-phase or form I of PVDF

The shift of Raman spectra of pureblend and the blend with 0.05 and 0.1 wt% are shown in Figure 6. The spectra present from 1580 cm⁻¹ to 1589 cm⁻¹ for G band, from 1341 cm⁻¹ to 1346 cm⁻¹ for D band and from 2682 cm⁻¹ to 2689 cm⁻¹ for G″ band. This shift may be indicates the possibility of SWCNTS-COOH to be attached with OH group in the side chain of polymer molecules.

Figure 7 depicts X-ray diffraction spectra of PVDF/PEO blend and the blend incorporated with 0.05 and 0.1 wt% of SWCNTs in the range 2θ = 10˚ - 80˚. The main peaks at 2θ ≈ 23.92˚, 42.21˚ and 46.62˚, referent to the diffractions in planes, (1 1 1), (0 4 2) and (1 1 4), respectively attributed to α-crystalline phase of PVDF. The peaks which due to β-phase of PVDF at 2θ = 20.10˚ (1 1 0) and 36.96˚ (2 0 0) which disappear with adding the filler. For PVDF phases, the peaks at 2q = 19.09˚ (020) and 39.71˚ (002) for α-phase, at 2q = 20.01˚ (110 or 200) and 35.48˚ (001) for β-phase and at 2q = 26.17˚ (022) for γ-phase are founded [28] [29] . There are two peaks are observed at 2q » 18.33˚ and 23.25˚ corresponding to (120) and (112) attributed to crystallite forms of PEO [30] .

On the other hand, all peaks of SWCNTs nanopowder are disappeared in doping samples. This indicates the complete dissolution of the filler in amorphous regions of the polymers revealed the distortion in crystal structure within polymeric matrices or as indicating to dissolution completely of SWCNTs in amorphous domains. A broad of the peaks is increased in broadness with decreased in their intensities suggesting that the amorphousregions.

It was observed that the reflection ‎of pure blend peaks at ‎2θ ‎= 26˚ and 27.1˚ disappeared which revealed that there is distortion in ‎crystal structure of the blend. The tendency of apparently diminution of crystallinity with ‎the increase of SWCNTs content in blend sample implies a decrease of the number of ‎hydrogen bonds that are formed between PEO and PVDF if present.

From all previously mentioned results, the interaction between SWCNTs and polymer blend results in decreasing crystallinity with rich amorphous phase. This amorphous nature is responsible for higher conductivity and confirms the complexation between SWCNTs and the polymer blend.

Surface morphology of the prepared films has been studied by scanning electron microscope (SEM). Micrograph in Figure 8 depicts the smooth and free surface of pure PEO/PVDF blend as in previous in literature. After loading SWCNTs, the film surface becomes rough with some small aggregates, but the single rode are well distributed in the entire surface region in polymeric matrices as shown in Figure 9(a) and Figure 9(b). Clear single rods of SWCNTs are observed in the images. The length of the individual rods is short with closed ends. An individual tubes or bundles of small tubes assemble to give thicker bundles. The Images show a twisted bundle consisting of SWCNTs. Furthermore, the nanotubes appear defect free with traces of amorphous carbon (black spots) deposits on the surface of the images.

Figure 10 shows TEM micrograph of pristine SWCNTs at 0.5 µm and 200 nm magnifications. It can be seen that the surface of purified SWCNTs is very clean and most of the impurity phases, such as amorphous carbon and graphitic nanoparticles are removed during purification of SWCNTs. The diameter of the SWCNTs is 8 - 14 nm. There are some black spots attributed to amorphous nature carbon. Figure 11 shows the micrograph of SWCNTs dispersion in polymer solution. SWCNTs disperse in polymeric solution results in uniformly dispersing. SWCNTs are implanted uniformly in the polymer solution and have intimate contact with these polymeric matrices. The broken ends of SWCNTs are observed revealing that the nanotubes broke apart rather than being pulled out from the fracture surface indicating the existence of strong interfacial bonding between the CNTs and the polymeric matrices. Moreover, the polymer blend could form a dense layer covering on the images of the nanocomposites showing that some defects like ragged and/or worm eaten on the tube walls. Also, the SWCNTs is arranged in different diameters and wrapped with PEO/PVDF.