Acoustical Investigations of Molecular Interactions in Polymer Solution of Pan/Clay Nano Composites and Dmso

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Table 2. Some thermo dynamical parameters for solution of PAN/Clay nano-composites in DMSO

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The almost constant behavior of r, w is as expected. Г shows a slight increase with increase of concentration in PAN (V) sample but it shows a regular decrease in its magnitude with rise in concentration in other samples. As Г points to the existence of quasi-crystalline structure in the solution so it points to more stronger association in solute-solvent molecules in solutions containing PNC1, PNC2 and PNC3 sample as compared to the solutions containing PAN(V) sample. (α/f)² reports a steady increase in its values in all samples under investigation. This trend of variation of (α/f)² is due to the addition of the higher molar weight solute (PAN) leading to the greater denseness of the solution. The greater absorption of ultrasonic wave energy by a denser solution is as expected.

Table 3. Some elastic parameters for solutions of PAN/Clay nano-composites in DMSO

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Table 4. Some non-linear parameters for solutions of PAN and PAN/Clay nano-composites in DMSO

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A perusal of Table 3 indicates that U_l, U_s, E, G, K and σ show slight but regular increase with increase in concentration from 0.1 to 0.6, for each sample solution. The increase in magnitude of these parameters is, due to the addition of PAN molecules (having higher molar weight) to the solution and also due to the enhanced molecular association among constituents of the solution, leading to the denseness of the system.

Several non-linear parameters such as C₁, , , S₀, S^*, S^*₀, F, K, K^”, K^’, f, η, α*, P_i, B/A, A^* and B^*, and δ are presented in the Table 4 to Table 6. The perusal of Table 4 indicates that C₁ value varies 7.957 to 7.990 and 7.937 to 7.967 for virgin PAN and PAN/Clay composites respectively. This is in agreement with the value of the weakly-associated liquids as reported by Tiwari et al. ^[7] and lower than polymers as reported by Singh et al. ^{[5, 6]}. This signifies the nonlinear variation of the volume expansivity of the system under investigations. The value range from 6.17 to 6.12 and 6.20 to 6.15 for virgin PAN and PAN/clay composites respectively. These values compare well with the values reported for molten alkali halides (~ 5 to 7) and polymers (~ 4 to 8). The result reported in Table 4 indicates that the value of the S₀ remains fairly constant within the acceptable range of experimental error. The estimated value of the S₀in general lies in the range 1.11 ± 0.01 for all the samples under study. These values are in good agreement with results reported by Sharma [8-9]^[8]. The calculated value of S* are 1.41 ± 0.01 for all the samples as compared 1.15 for polymers as reported by Reddy et al. ^[10]. It is interesting to note that the value of S_o* is 1.15 for these samples and higher than that of polycrystalline solids.

Table 5. Some non-linear parameters for solutions of PAN and PAN/Clay nano- composites in DMSO

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The result reported in Table 5 point out that the values of ‘F’ ranges from 2.074 to 2.079 and 2.071 to 2.076 for virgin PAN and PAN/ clay nano-composites respectively. These values are more than that observed for polymers, molten alkali halides, liquid alkali metals and ionic liquids as reported by Sharma ^[9]. The average value of ‘f’ for all the samples under study are found to be about 0.198 as compared to 0.20 for saturated hydrocarbons and about 0.15 for fluorocarbons. This points out that free volume values for theses samples, in the given concentrations range, are almost equal to the free volume values for saturated hydrocarbons but are slightly larger than that for fluorocarbons, as reported by Sharma ^[11]. The quasi constancy of ‘f’ at given temperature and concentrations range has significance in relation to the universal value of ‘f’ at the glass transition temperature Williams et. al. ^[12]. The average value of n found to be 15.37 and about 15.31 for virgin PAN and PAN/ clay composite respectively. These values of n have magnitude more than that reported by Saczkiewiez for polymers and fluorocarbons. The values of K, K’ and K” range from 3.46- 3.50; 4.0465-4.0665, and 0.571-0.581 for all the samples. The K’ and K” have recently been shown as an important factor which has a significant effect on the thermo acoustical properties of liquids fluorocarbons.

Table 6. Some non-linear parameters for solutions of PAN and PAN/Clay nano composites in DMSO

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