International Journal of Modern Applied Physics, 2012, 1(2): 83-96 International Journal of Modern Applied Physics ISSN: 2168-1139 Florida, USA Journal homepage:www.ModernScientificPress.com/Journals/ijmep.aspx Article

The Accessibility of Change of the Structural, Morphological and Thermal Properties by Intermolecular Hydrogen Bonding in PEO/PVA Blend Containing MnCl2 E. M. Abdelrazek1, I. S. Elashmawi2,3,*, A. Hezma2, A. Rajeh1 1

Physics department, Faculty of science, Mansoura University, Mansoura Egypt.

2

Spectroscopy department, Physics division, National Research Center, Giza, Egypt.

3

Physic department, Faculty of Science, Taibah University, Al-Ula, Saudia Arabia.

* Author to whom correspondence should be addressed; Email: [email protected], Tel., +2 01003715770 Article history: Received 25 August 2012, Received in revised form 7 October 2012, Accepted 8 October 2012, Published 9 October 2012.

Abstract: Polyethylene oxide/polyvinyl alcohol (PEO/PVA) doped with different concentrations of MnCl2 were prepared by casting method and studied by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Ultraviolet-visible optical absorption (UV-Vis.), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). IR absorption spectra indicated there was a chemical reaction between PEO/PVA and MnCl2. X-ray spectra for MnCl2 indicated the complete dissolution of the filler in amorphous regions of the blend resulting in a decrease of crystallinity with rich amorphous phase in the polymer. Uv-Vis. spectra suggested the presence of an optical band gap which depends on the filler concentration and arises due to the variation in the crystallinity in the polymeric matrices. DSC and TGA data shown that the addition of MnCl2 to PEO/PVA films decreased their thermal stability with weakening bond strength. The SEM of the surface of the films presented a rougher surface with some small aggregates compared to the pure blend which has a good distribution in the entire surface region with smooth ganglia- ‎like hills. This is ‎attributed ‎to a strong increase of lamellar twisting period and to a decreased amorphous region within the polymeric matrixes. Keywords: Polymer blend; FT-IR; X-ray; SEM; Thermal stability.

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1. Introduction Polymer blends play an important role because of their relatively simple preparation methods and diverse resulting properties [1]. Interest in studying polymer blends has considerably increased due to their significant industrial applications [2]. Blends with improved characteristics are produced by blending two or more polymers in order to combine their properties for certain purposes. Polyvinyl alcohol (PVA) is the most widely produced water soluble synthetic polymer over a wide range of temperatures depending on its degree of hydrolysis, molecular weight and tendency to hydrogen bond in aqueous solutions [3]. Moreover, PVA is also nontoxic, potential material having high dielectric strength, good charge storage capacity and dopant dependent electrical and optical properties [4]. PVA has been found to have a wide range of applications in the industrial sector and it has been attractive in different areas of science and technology [5, 6]. Poly(ethylene oxide) (PEO) based amphiphilic block copolymers exhibit interesting selfassembling properties both in solution as well as in bulk [7]. The hydrophobic sequences in these polymers are generally based on styrene [8] dienes [9] or hydrogenated aliphatic polyolefin blocks [10]. Filler additives were added to polymer or polymer blend to improve and modify its properties. Transition metals have influence on the structural, optical, morphological and thermal properties of polymer blend. Most of the early works on metal/polymer composites are patented, and little systematic investigation has been carried out in this field, especially on the particulate composite systems. In the present work, PEO/PVA blend doped with different concentrations of MnCl2 have been prepared by casting method. The structural, optical, thermal and morphological characteristics of the prepared composites were studied with various techniques to verify the influence of Mn-ions on their physical properties.

2. Experiments 2.1. Materials Both polyethylene oxide supplied from ACROS, New Jersey, USA with MW  900 and polyvinyl alcohol from Merck, Germany) with MW  14.000 were used as a basic polymeric materials. Manganese chloride (MnCl2) were purchased from Sigma-Aldrich Co., All chemicals were used as received. 2.2. Preparation Method Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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Equal weight of PEO and PVA (50/50 wt/wt %) were dissolved in double distilled water separately and then the polymer blend solution was stirred continuously about 6 h at 70 C until a homogenous viscous liquid was formed . MnCl2 was dissolved in double distilled water also in the same condition. The resulting solution of MnCl2 particles was added to the polymer blend solution with mass fraction 0.5, 1.0, 2.5, 5.0, 10 and 15 wt.%. The resulting solution was then cast to Petri dishes and at 70 ˚C for about 72 h. After drying, the films were peeled from Petri dishes. Films of thickness ranging from 0.15 to 0.20 mm were obtained and kept in vacuum desiccators until use. 2.3. Measurement Techniques FT-IR absorption spectra were carried out for different films using the single beam Fourier transform-infrared spectrometer (Nicolet iS10, USA) at room temperature in the spectral range of 4000-400 cm-1. X-ray diffraction scans were obtained using PANalytical XPert PRO XRD system using CuK radiation (where,  = 1.540 Å, the tube operated at 30 kV, the Bragg’s angle (2) in the range of (10-50). UV-Vis absorption spectra were measured in the wavelength region of (190-900) nm using spectrophotometer (UNiCAM UV/Vis Spectrometer, England) to study the change in structures of the samples due to the addition of the fillers and their optical properties. The morphology of the films was characterized by scanning electron microscope using (Quanta FEG 250), operating at 200V-30 kV accelerating voltage magnification 14x up to 1000x. Surfaces of the samples were coated with a thin layer of gold (3.5 nm) by the vacuum evaporation technique to minimize sample charging effects due to the electron beam. The differential scanning calorimetry of the prepared films was carried out by using (SETARAM labsys TG-DSC 16) from room temperature to 450 C with a heating rate of 10 C min-1. Shimadzu TGA-50H was used for the Thermogravimetric ‎analysis of the samples. A small amount of the sample was taken for ‎the analysis and the samples were heated from room temperature to ‎550 °C at a rate of 10 °C min-1 in nitrogen atmosphere on platinum ‎cell.‎

3. Results and Discussion 3.1. Fourier Transform -Infrared Analysis In the present work, IR spectra were used to establish the interaction ‎between PEO and PVA doped with MnCl2 as filler, which causes some ‎changes in the vibrational modes and bands position. Figure 1 depicts the ‎IR spectra of pure PEO and pure PVA. For pure PEO, main characteristic bands of PEO can be observed. A ‎sharp band at 2888 cm-1 is attributed to CH2 stretching of methylene group. ‎The bands at around 1464 cm-1 and 1339 cm-1 Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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represent CH2 scissoring and ‎CH2 asymmetric bending, respectively. The relatively small band at around ‎1240 cm-1 is assigned to CH2 symmetric twisting, C-O-C stretching mode ‎has sharp band at 1108 cm-1 out-of-plane rings C-H bending mode at 962 ‎cm-1 .‎ For pure PVA, the characteristic absorption bands at about 3349 and ‎1427cm-1 are assigned to

‎

OH stretching and bending vibration of hydroxyl ‎group. The band corresponding to methylene group (CH2) asymmetric ‎stretching vibration occurs at about 2940 cm-1. The vibrational band at ‎about 1736 cm-1 corresponds to C=O stretching of PVA. The band at ‎ about 840 is assigned to stretching mode of CH2. The band at about 1093 cm-1 corresponds to C-O stretching of acetyl ‎group present on the PVA backbone. The absorption band at 954 cm-1 ‎is assigned to CH2 stretching [11-13]. Figure 2 shows the spectra of pure blend ‎and the blend with 0.5, 1.0, 2.5, 5, 10, and 15 wt. % of MnCl2.‎ From the figure, the relative ‎intensities of some characteristic vibrational bands for those MnCl2 ‎blends are decreased. This indicates that the amorphous regions of the ‎prepared samples are augmented with increasing the filler. The shifts of CH2 stretching vibration from 2893 cm-1 to 2883 cm-1, CH2 asymmetric bending from 1343 cm-1 to 1335 cm-1 and out-of-plane rings C-H bending mode from 966 cm-1 to 962 cm-1 were observed. These indicate the ‎chemical interactions of MnCl2 with the

1108

5.0 2.5

0.5

966

blend

1343

1.0

3319

PEO

2893

PVA

962 842

10

Absorbance (a. u.)

Absorbance (a. u.)

15

1736

PEO / PVA + MnCl2 ( wt%)

1466 1335

2888

3340

polymer blend.

blend 4000

3500

3000

2500

2000

1500

1000

-1

Wavenumber( cm )

Fig. 1: FT-IR spectra of pure blend, pure PEO and pure PVA

500

4000

3500

3000

2500

2000 -1

Wavenumber( cm )

1500

1000

500

Fig. 2: FT-IR spectra of ‎blend and ‎the blend with different concentrations of MnCl2.

3.2. X-ray Diffraction (XRD)‎ XRD analysis is very useful to investigate the structure of the polymeric materials and it enables us to find out whether a material is crystalline or amorphous.‎ Figure 3 presents the X-ray spectra of pure PEO and PVA and their blend. Figure 4 depicts the X-ray diffraction of PEO/PVA pure blend and the blend with ‎different concentrations of MnCl2 in the range 2θ =10-50. It is ‎known that pure PEO has two well defined reflection peaks at 2θ values 19 and 23.2 ‎[14] while pure PVA exhibits only a broad and shallow diffraction feature around the 2θ ‎value of 19.5 [15]. Pure blend Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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sample shows well-defined broad peaks at around 19 ‎and 23, which indicates a semicrystalline nature. After adding MnCl2, it was observed that the reflection ‎of pure blend peaks at ‎2θ‎= 26 and 27.1 disappeared above 1.0 wt% which revealed that there is distortion in ‎crystal structure of the blend. The tendency of apparently diminution of crystallinity with ‎the increase of MnCl2 content in blend sample implies a decrease of the number of ‎hydrogen bonds that are formed between PEO and PVA if present. Also, this might be a ‎result of dilution effect of Mn2+ when mixed with polymer, which suppress recrystallization of broken blend polymer chains and inhibit crystal ‎growth. The two peaks at 2θ= 19.1 ‎and 23.3 , have been found to be increased in broadness ‎and decreased in intensity for‎ wt‎ ≥‎ 2.5%.‎‫ ‏‬This results reveal the increase in amorphous nature ‎the films. Moreover, there are no new peaks appeared for MnCl2. This indicates the complete dissolution of the filler in amorphous regions of the polymers [16]. From all previously mentioned results, the interaction between the filler and polymer blend results in decreasing crystallinity with rich amorphous phase. This amorphous nature confirms the complexation between the filler and the polymer blend.

Intensity (a. u.)

MnCl2

10

20

30

40

50

2 (degree)

PVA

PEO/ PVA + MnCl2 (wt%) 15

5.0 2.5

PEO Intensity (a. u.)

Intensity (a. u.)

10

1.0

0.5

blend blend

10

20

30

40

50

10

2 (degree)

Fig. 3: X-ray diffraction scans of pure blend, pure PEO and pure PVA.‎

‎Fig.

‎

20

30

2 (degree)

40

50

4: X-ray diffraction scans of pure blend and blend filled with different concentrations of MnCl2.

3.3. Ultraviolet-visible Spectroscopy (UV-Vis.) Figure 5 displays the UV-Vis absorption spectra in the range of (190 – 800) nm of ‎PEO/PVA films filled with various concentration of MnCl2 content exhibit very small absorbance in the ultraviolet range (200-380 nm) while in visible region show very high absorbance. Consequently it may be Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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used as optically ‎transparent UV absorbing film materials that are easily manufactured by processes that ‎do not utilize volatile organic compounds, and whose polymer components are not ‎environmentally hazardous. The spectrum of pure blend sample exhibited ‎three absorption bands, an intense band at 192 nm ascribed to the ‎presence of some residual acetate groups of PVA and/or chromophoric groups of ‎PEO, were assigned to the existence of carbonyl ‎groups ‎associated with ethylene unsaturation [17]‎ and a hump or shoulder at 215 nm and very small band at 375 nm may be due to π→π* (K-band) and n→π* (R- band) ‎electronic transitions respectively [18]. In addition, there are no absorption bands on the ‎visible region for all samples since the films are transparent. ‎The

absorption intensity of the MnCl2 band at 215 nm and 375 nm become faint

at ‎concentrations higher than 5 wt%. However, only the peak position of the band at 210 nm ‎shifted toward MnCl2(wt%)

higher wavelengths by about 10 nm with increasing MnCl2 concentrations. These shifts in the bands indicate mainly between Mn

2+

Absorbance (a. u.)

the formation of inter/intra molecular hydrogen bonding ions with the adjacent OH groups

that are in consistence with IR results. As the MnCl2

15

10

concentration increases, inter/intra hydrogen bonding

5.0 2.5 1.0

increases and hence absorption. This is in accordance

0.5

with the Beer’s law, i.e. the absorption is proportional to

blend 200

the number of absorbing molecules. The absorption edge in the blend reflects the variation in the energy band gap.

300

400

500

600

Wavelength (nm)

700

800

900

Fig. 5: UV–vis spectra of PEO/PVA blend and the blend filled with different concentrations of MnCl2.

3.3.1. Determination of optical energy gap (Eg) The study of optical absorption gives information about the band structure of organic compound. Semiconductors are generally classified into two types: a) direct band gap and b) indirect band gap. In direct band gap, the top of the valence band and the bottom of the conduction band both laid at the same zero crystal momentum (wave vector). If the bottom of the conduction band does not correspond to zero crystal momentum, then it is called indirect band gap [19]. In indirect band gap, transition from valence to conduction band should always be associated with a phonon of the right magnitude of crystal momentum [20]. Davis and Shalliday [21] reported that near the fundamental band edge, both direct and indirect transitions occur and can be observed by plotting (h)2 and (h)1/2, respectively, as a function of energy (h), where h is Planck's constant. The analysis of Thutpalli and Tomlin is based on the following relations [22]: Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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(nh ) 2  C1 (h  E gd )

(1)

1

(nh ) 2  C 2 (h  E gi )

(2)

where, h is the photon energy, Egd, the direct band gap, Egi , the indirect band gap, n, integer, C2, C2, constants and  is the absorption coefficient. The absorption coefficient () can be determined as a function of frequency using the formula [23]:     2.303 

A d

(3)

where, A is the absorbance and d is thickness of the sample under investigation. By plotting (h)1/2 versus photon energy (h) as shown in Figure ), each linear portion indicates a band energy gap (Eg). It is will be noticed that the curves are characterized by the presence of an exponentially decay tail at low energy [24]. For indirect electron transitions that require phonon assistance, the ‎absorption coefficient depends on the incident photon energy. Hence the ‎indirect band gap values were obtained from the plots of (αh)1/2 versus h at ‎the intercepts of the energy axis on extrapolating the linear portion of the ‎curves to zero absorption value in figure 6.

(a) (b) (c) (d) (e) (f) (g)

18000

15000

blend 0.5% 1.0% 2.5% 5.0% 10% 15%

(f) (g) (e) (a)

(h)

1/2

12000

(d)

9000

(c)

(b)

6000

3000

0 2

3

4

5

6

7

h(ev)

Fig. 6: Optical energy band gap of PEO/PVA blend and the blend with different concentration of MnCl2.

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For ‎blend the indirect band gap lies at 5.75 eV while for 0.5, 1.0, 2.5, 5.0, 10 and ‎15 wt% MnCl2 doped PEO/PVA, it lies at 5.7, 5.67, 5.6, 5.38, 5.2 and 5.34 ‎eV. ‎ It is clear that, the values of these energies are decreased with increasing Mn-ions content. ‎This indicates that there are charge transfer complexes arose between the polymer blend ‎and Mn-ions. 3.4. Differential Scanning Calorimetry (DSC)‎ Thermal techniques are the convenient tool to determine the physical and chemical changes such as phase transitions, glass transition temperatures (Tg) and melting parameters (melting point Tm, thermal decomposition temperature Td, enthalpy of fusion Hf). A temperature range of 30–500 oC at a heating rate of 10 oC min-1 was utilized under nitrogen atmosphere. The thermal properties were examined by DSC to estimate how the thermal transitions of the prepared films were affected by the different concentrations of MnCl2 as shown in figure 7. Melting temperature and decomposition temperature are reported in Table 1.‎

MnCl2 (Wt%) 15 10 5.0

Exo.

1.0

Endo.

2.5

0.5

pure

0

100

200

300

o

Temperature (C )

Fig. 7: DSC thermograms of PEO/PVA blend and blend with ‎different concentrations of MnCl2.

The DSC thermograms of all samples showed endothermic and exothermic peaks. The first endothermic peak at ‎69.6˚C was attributed to the overlapping of Tm1 of PEO and Tg2 of PVA. The other exothermic peak at 165.03 oC was assigned to Tm2 of PVA. The third endothermic peak Td ‎was observed in the range between (262 up to 293) oC [25]. Therefore, the glass transition peak of Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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PVA ‎might overlap with the melting peak of PEO in DSC thermogram and it could be difficult ‎to observe the glass transition temperature separately. It is clear from table 1 that the ‎position of Tm1and Tm2 peaks remains unaltered nearly with increasing MnCl2 content in blend ‎sample. While the position of Td peak shifted to lower temperatures. This is an indication of the decrease of thermal stability and weakening the ‎bond strength. It is generally accepted that the presence of two separate Tg,s in polymer ‎blends provides a strong signature of immiscibility. Immiscible blends may be further ‎described as compatible or incompatible. In the present case, the pure blend of ‎PEO/PVA and doped with Mncl2 are immiscible . ‎ The area under crystalline melting endothermic peaks is correlated to the degree of crystallinity (c). If it is assumed that all blend PEO/PVA crystal from present has the same heat of fusion ∆H(100)=163 J/g [26] for completely crystalline blend PEO/PVA sample, then ∆Hf (measured directly from DSC themograms) can be related to the crystallinity of the sample by the following equation [27]: crystallinity (  c ) 

H f H f (100)

100

(4)

The calculate values of the degree of crystallinity and the values of melting temperature of the blends from DSC thermogram are listed in Table 1. It is clear from the table that there is a decrease in the degree of crystallinity after the addition of different ‎concentration of MnCl2 for all samples. This behavior reflects that the addition of MnCl2 to ‎the PEO/PVA sample decreases the intermolecular interaction and/or cross linking PEO ‎and PVA components. This result is consistent with that obtained from XRD data.‎ Table 1: DSC results and the activation energy of blend and blend with different concentration of Mncl2. MnCl2 E Tm1 (C) Tm2 (C) Td (C) c Kg/mole (Wt%)

0.0

69.60

165.03

293

40.00

96.14

0.5

69.01

166.92

292

36.81

105.13

1.0

69.32

167.72

274

32.80

126.27

2.5

69.52

169.06

271

31.62

155.43

5.0

69.01

165.92

269

26.43

176.18

10

69.63

167.53

264

26.01

196.03

15

69.04

168.69

262

25.62

217.36

3.5. Thermogravimetric Analysis (TGA)‎ Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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Thermogravimetric analysis is a process in which substance is decomposed in the ‎presence of heat which causes bonds within the molecules to be broken. The sample ‎weight decreases slowly as the reaction begins, then decreases rapidly over a ‎comparatively narrow temperature range and finally levels off as the reactants become ‎spent. The shape of TGA curve depends primarily upon the kinetics parameters. The ‎values of these parameters are important in estimation of thermal stability of the samples [28]‎. Figure 8 shows TGA thermograms of weight loss as a function of temperature for pure PEO/PVA blend and their composites with a heating rate of 10 C.min-1 in the temperature range from room temperature to 550 C. The initial weight loss for the other samples occurs at 59–235 C due to the presence of MnCl2 in the samples. In general, the major weight losses are observed in the range of 235 – 450 C for all the prepared samples. This may be correspondent to the structural decomposition of the polymer blends and their complexes. From this figure, the prepared samples are stable over 463 C. From the figure, we noticed that, the thermal

120

MnCl2(wt%)

decomposition of all samples shifts slightly towards 100

indicating the decrease of polymer thermal stability. By comparing the values of the final weight losses, it was found that, the value of the pure PEO/PVA blend

Weight (Wt%)

low temperature ranges than in pure PEO/PVA blend

80

60

10

40

film was high than that of the filled samples. This may be due to the chemical reaction between blend and the filler; then the addition of MnCl2 to

100

200

300

400

500

0

Temperature ( c)

PEO/PVA blend films decrease their thermal stability. 3.5.1. Determination of the activation energy

15 0.5 2.5 blend 5 1

20

Fig. 8: TGA thermograms of weight loss as a function of temperature.

The activation energy for the thermal decomposition for TGA measurements of the present samples, which depends on the residual mass, can be calculated using integral equation of Coats and Redfern [29]:

log[

1  (1   )1n R 2 RT 1 E ]  log [1  ] 2 E E 2.303 RT T

(5)

where T is the absolute temperature, E is the activation energy in J/mol, R is the universal gas constant (8.3136 J/mol K), n is the order of reaction and  is the fractional weight loss at that particular temperature calculated as:

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Int. J. Modern App. Physics. 2012, 1(2): 83-96 wi  wt wi  w f



93

(6)

where wi is the initial weight, wt is the weight at given temperature and wf is the final weight of the sample. For n1, Eq. (5) reduces to:

log[

By ploting  log[

 log(1   ) R 2 RT 1 E ]  log [1  ] 2 E E 2.303 RT T

(7)

 log(1   ) ] against 1000/T for each sample, we obtain straight line (not here). The T2

value of activation energy (E) was calculated from the slope of the plot as:

E  2.303R  slope

(8)

The calculated activation energies of the samples are shown in Table (1), where it is clear that the values of the activation energy are increased from 96.14 to 217.36 KJ/mole with increasing the MnCl2 content which indicates that the MnCl2 is intensively affects the polymer blend. 3.6. Scanning Electron Microscopy (SEM)‎ The SEM is used to investigate fully the effect of MnCl2 content and to ‎examine the dispersion of MnCl2 particles in the polymeric matrix, ‎Figure 9 shows the microstructures of blend without and with different ‎concentrations of MnCl2 content. SEM suggests the doping dependence of ‎the morphological structure. Image (a) shows polymer blend which is transparent and is ‎shown to be in a uniform morphology revealing a rather smooth surface. As the content of ‎MnCl2 increases up to 5% the films surface becomes roughness with some small ‎particles (white spot) aggregates (see images from 0.5-5%). This indicates segregation of MnCl2 in ‎the polymeric matrixes and this may be confirmed the interaction and complexation ‎between them. Also, this fact shows that a good adhesion between the surface of MnCl2 and polymer matrix has been established by the organic surface ‎modification [30]. The white spots white on the backscattered ‎images seem to be agglomerates of MnCl2 particles, which increase with increasing the ‎concentration of MnCl2. ‎

The ‎image of 10% shows smooth ganglia- ‎like hills with some wrinkles (spherical longitudinal

shapes) [31]. This could be ‎attributed ‎to a strong increase of lamellar twisting period and to a decreased radial ‎growth rate in amorphous regions within the polymeric matrixes. ‎ Image of 15% Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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gives rise to crystalline domains with coarse spherulitic ‎structure. This is ‎due to MnCl2 segregated into interlamellar or ‎intercrystalline regions of the blend.‎

Fig. 9: SEM images of: PEO/PVA blend and PEO/PVA doped with: 0.5, 2.5, 5.0, 10, and 15 wt% MnCl2.

4. Conclusion FT-IR data revealed that the intensities of some vibrational bands for the prepared films are decreased indicates that the amorphous regions are augmented with increasing MnCl2. XRD showed that there are no new peaks appeared for MnCl2 indicating the complete dissolution of the filler in amorphous regions with a decreasing in the crystallinity. UV-Vis. data revealed that the absorption intensity of MnCl2 bands became faint at ‎concentrations ˃ 5 wt% and the shift of the band at 210 nm ‎ toward higher wavelengths with increasing MnCl2 concentrations indicated the formation of inter/intra molecular hydrogen bonding between Mn2+ ions and OH group. The values energies gap were decreased with increasing Mn-ions content due to charge transfer complexes arose between the polymer blend ‎and Mn-ions.‎ DSC and TGA data provided that thermal stability decrease as a result of addition of MnCl2 to the blend and there is a decrease in the degree of crystallinity for all samples. This behavior reflects that the addition decreases the intermolecular interaction and/or cross linking PEO ‎and PVA components. SEM ‎images showed smooth ganglia ‎like hills with some wrinkles ‎attributed ‎to a strong increase of lamellar twisting period. ‎ References [1] G. O. Shonaike and G. P. Simon, "Polymer Blends and Alloys", 1st Ed., Marcel Dekker, New York, 1999. Copyright © 2012 by Modern Scientific Press Company, Florida, USA

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