Der Pharma Chemica
Journal for Medicinal Chemistry, Pharmaceutical Chemistry, Pharmaceutical Sciences and Computational Chemistry

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Research Article - Der Pharma Chemica ( 2018) Volume 10, Issue 3

Thermo-physical Studies on Molecular Interactions in Liquid Binaries of Diethyl Malonate and Isomeric Xylenes at Various Temperatures

Venkateswararao VNSR1, Satyanarayana GR2, Beebi SK3 and Rambabu C1*

1Department of Chemistry, Acharya Nagarjuna University, Guntur-522510, Andrapradesh, India

2Department of Chemistry, Sir. C.R. Reddy PG College, Eluru-534007, Andrapradesh, India

3Department of Chemistry, Y.V.N.R. Govt. Degree College, Kaikaluru-521333, Andrapradesh, India

*Corresponding Author:
Rambabu C
Department of Chemistry
Acharya Nagarjuna University
Guntur-522510, Andrapradesh, India

Abstract

Densities and viscosities of binary liquid mixtures of diethyl malonate with isomeric xylenes were reported at (303.15, 308.15, 313.15 and 318.15 K). From the experimental data, deviation in Viscosity (Δη) and excess Gibbs free energy of activation of Viscous flow (ΔG*E) were evaluated. The deviations in viscosity and excess Gibbs free energy of activation of viscous flow were correlated with Redlich-Kister polynomial equation. Viscosity theories like Grunberg-Nissan, Katti-Chaudhri, Heric-Brewer, Hind et al. and McAllister four body models have been applied to correlate the viscosity of binary mixtures.

Keywords

Density, Viscosity, Gibbs free energy, Molecular interaction

Introduction

Density and viscosity play a vital role in analyzing the theoretical and physical properties of binary liquids. The experimental results of these properties of the binary liquids attracted the attention of large number of engineering and chemical industries [1]. The viscosity of binary liquids is a tremendous tool in many chemical applications such as molecular structure, mass, liquid stream, heat transfer and capillary electrophoresis [2]. Moreover, the investigation of excess thermodynamics and transport properties for binary mixture gives essential data concerning the deeper understanding of the molecular liquid structure and intermolecular interactions [3]. Xylenes are habitually utilized as octane enhancer in vehicles [4]. They likewise have different applications in printing, elastic, petrochemical ventures and leather industries. Diethyl Malonate (DEM) is a diethyl ester of malonic acid.

In this study, viscosities and densities are measured at four temperatures (303.15, 308.15, 313.15 and 318.15) K for binary mixtures of Diethyl Malonate (DEM) with o-Xylene (OX), m-xylene (MX) and p-Xylene (PX). Deviation in Viscosity (Δη) and excess Gibbs free energy of activation of Viscous flow (ΔG*E) have been computed from Density (ρ) and Viscosity (η) information to understand the nature of forces working between them. Semi-empirical viscosity models, for example, Grunberg and Nissan [5], Katti and Chaudhri [6], Heric and Brewer [7], Hind et al., [8] and McAllister [9] four body models are utilized to compare the investigational results with the theoretical viscosities.

Experimental Section

Materials and methods

Diethyl malonate and isomeric xylenes provided from Merck were purified as depicted in the literature [10,11]. The unadulterated chemicals were stored over activated molecular sieves to decrease water content before utilize. All the binary liquid mixtures are prepared gravimetrically utilizing an electronic balance (Shimadzu AY 120) with an uncertainty of ± 1 × 10-7 kg and stored in sealed shut containers. The uncertainty on mole fraction is evaluated to be 1 × 10-4. It is guaranteed that the mixtures are appropriately mixed and the estimation of the required parameters was done within one day of preparation. The densities (ρ) of unadulterated liquids and their mixtures are determined utilizing a 10-5 m3 double-arm Pycnometer and the values from triplicate replication at every temperature are reproducible within 2 × 10-1 kg.m-3 and the uncertainty in the estimation of density is observed to be 2 parts in 104 parts. The reproducibility in mole fractions was within ± 0.0002. Temperature control for the estimation of viscosity and density is accomplished by utilizing a microprocessor assisted circulating water bath regulated to ± 0.01 K, utilizing a corresponding temperature controller. Satisfactory precautionary measures were taken to limit evaporation losses during the genuine estimations. Exploratory estimations of density and viscosity at 303.15-318.15 K with those detailed in the literature [12-15,4] are provided in Table 1.

303.15 K 308.15 K 313.15 K 318.15 K
ρ (10-3 kg m-3) η (m Pa s) ρ (10-3 kg m-3) η (m Pa s) ρ (10-3 kg m-3) η (m Pa s) ρ (10-3 kg m-3) η (m Pa s)
Expt. Lit. Expt. Lit. Expt. Lit. Expt. Lit. Expt. Lit. Expt. Lit. Expt. Lit. Expt. Lit.
1.0443 1.0443a 1.73 1.732b 1.0385 1.0387a 1.602 1.602b 1.0335 1.0336a 1.456 1.458b 1.0313 1.4244 1.425b
0.8704 0.8707c 0.7061 0.7051c 0.8695 0.8694c 0.665 0.6652c 0.8678 0.8677c 0.6226 0.6211c 0.8658 0.8659c 0.569 0.5691c
0.8555 0.8557c 0.555 0.5530d 0.8485 0.8487c 0.5224 0.523d 0.8455 0.8458c 0.493 0.493d 0.8403 0.8405c 0.4686 0.468d
0.8529 0.8529e 0.577 0.5782c 0.8468 0.8460c 0.551 0.5501c 0.8428 0.8430c 0.505 0.5065c 0.837 0.8369c 0.492 0.4912c

Table 1: Comparison of density (ρ) and Viscosity (η) of the pure liquids with literature data

Theoretical considerations

The viscosity deviations (Δη) were calculated utilizing:

image(1)

Where, η12 is the viscosity of the binary mixture, x1, x2 and η1, η1 are the mole fraction and the viscosities of unadulterated segments 1 and 2, respectively. The dynamic viscosities of the liquid mixtures have been computed utilizing observational relations given by Grunberg-Nissan, Katti-Chaudari, Heric-Brewer, Hind et al. and McAllister four body models. Grunberg and Nissan [5] proposed the following equation for the estimation of viscosity of liquid mixtures:

image(2)

Where, G12 is an interaction parameter, which is an element of viscosity of segment liquids 1 and 2 and temperature. Katti and Chaudhri [6] equation for the dynamic viscosity of the liquid mixture is:

image(3)

Where, Wvis is an interaction term, Heric and Brewer [7] determined the following equation to calculate the viscosity of the binary liquid mixtures:

image(4)

Where, Δ12 is the association term and other symbols have their typical importance. The expression to determine the viscosity of the binary liquid mixtures proposed by Hind et al. [8] is given by:

image(5)

Where, H12 is an association term, McAllister [9] four body interaction model was generally used to correlate kinematic viscosity (v) information. The 2 parameter McAllister equation based on Eyring’s theory of absolute reaction rates, considered collaborations of both like and unlike molecules by a two dimensional four body model. The four body model was characterized by the connection:

image(6)

Where, Z1112, Z1122 and Z2221 are model parameters and Mi and Vi are the molecular mass and kinematic viscosity of pure component i. To perform a numerical comparison of the correlating capability of above equations, we have calculated the standard percentage deviation (σ %) utilizing the connection:

image(7)

Where, k speaks to the quantity of numerical coefficients in the respective equation. These parameters assessed by a non-linear regression analysis based on a least-squares strategy and given their standard percentage deviation (σ %) in Table 2

T/K G12 σ Wvis/RT σ Δ12 σ H12 σ Z1112 Z1122 Z2221 σ
Diethyl malonate + o-xylene
303.15 1.5107 0.0638 1.4823 0.064 1.5957 0.065 1.8831 0.0178 1.7387 1.7718 1.4772 0.0045
308.15 1.4092 0.0522 1.3756 0.0523 1.4943 0.0533 1.7068 0.0175 1.5858 1.6464 1.327 0.0062
313.15 1.3491 0.0437 1.312 0.0439 1.4343 0.0447 1.5497 0.0163 1.433 1.5215 1.1926 0.0058
318.15 1.2889 0.0371 1.2477 0.0372 1.3741 0.0381 1.4214 0.0189 1.3447 1.4864 1.0561 0.0034
Diethyl malonate + m-xylene
303.15 1.8886 0.0921 1.8215 0.0916 1.9731 0.0932 1.8147 0.0172 1.7369 1.6312 1.4696 0.005
308.15 1.7753 0.0761 1.7041 0.0754 1.86 0.0771 1.6418 0.0165 1.5816 1.5156 1.3125 0.0057
313.15 1.6888 0.0627 1.614 0.0621 1.7735 0.0636 1.4897 0.0158 1.4256 1.4121 1.1678 0.0057
318.15 1.5748 0.0509 1.4945 0.0504 1.6597 0.0519 1.3796 0.0188 1.3406 1.4054 1.036 0.003
Diethyl malonate + p-xylene
303.15 1.8996 0.0932 1.8235 0.0925 1.9841 0.0943 1.8712 0.0173 1.763 1.6646 1.519 0.0048
308.15 1.7834 0.0773 1.7059 0.0766 1.868 0.0784 1.7081 0.0169 1.6089 1.5587 1.3698 0.0056
313.15 1.6945 0.0629 1.616 0.0623 1.7793 0.0639 1.518 0.0158 1.4389 1.43 1.1904 0.0056
318.15 1.5821 0.0517 1.4988 0.0512 1.667 0.0527 1.4291 0.0187 1.3614 1.4385 1.0769 0.003

Table 2: Interaction Parameters and the corresponding standard deviations (σ) for the binary mixtures of diethyl malonate and studied isomeric xylenes at various temperatures

On the premise of the theories of absolute reaction rates [16], the excess Gibbs free energy of activation of viscous flow was computed by utilizing the connection:

image(8)

Where, η and Vm are the dynamic viscosity and molar volume of the mixture. η1, η2 and V1, V2 are viscosity and molar volume of pure components 1 and 2 individually. R is the real gas constant and T is the absolute temperature. The composition dependence of Δη and ΔG*E(YEcal) for each mixture are fitted to Redlich-Kister polynomial equation [17]:

image(9)

The coefficients of Ai-1 in the above equation alongside the standard deviation σ (YE) have been ascertained. These coefficients are the adjustable parameters to get best - fit values of YEcal. The standard deviations σ of YEcal were computed by utilizing the connection:

image(10)

Where, m is the quantity of experimental data points and n is the number of coefficients considered and YEexpt, YEcal are the values of experimental and calculated property (Δη and ΔG*E) separately.

Diethyl malonate is an aprotic solvent which has a solid inclination to pull electron in carbon – oxygen bond towards itself. It has a dynamic methylene gathering and shows dipole-dipole interactions in the unadulterated state. The investigational values of viscosity and computed estimations of deviation in viscosity and excess Gibbs free energy of activation of viscous flow for three binary mixtures (DEM+OX/MX/PX) at various temperatures (303.15, 308.15, 313.15 and 318.15) K are displayed in Table 3. Excess/deviation quantities are correlated by Redlich- Kister polynomial as an element of temperature. The fitting coefficients Ai-1 for all the three binary mixtures are recorded in Table 4 along with their standard deviation σ (root mean square deviation).

303.15 K 308.15 K 313.15 K 318.15 K
x1 η Δη ΔG*E η Δη ΔG*E η Δη ΔG*E η Δη ΔG*E
Diethyl malonate + o-xylene
0.0000 0.706 0 0 0.665 0 0 0.623 0 0 0.569 0 0
0.0812 0.875 0.086 352.37 0.808 0.067 309.93 0.752 0.061 303.83 0.684 0.046 282.21
0.1658 1.051 0.175 618.62 0.971 0.151 584.6 0.889 0.128 546.14 0.812 0.101 523.5
0.2542 1.236 0.27 824.02 1.14 0.237 792.16 1.046 0.211 768.99 0.953 0.167 726.62
0.3465 1.387 0.326 901.74 1.275 0.285 866.4 1.164 0.252 838.05 1.076 0.211 817.98
0.443 1.509 0.349 894.81 1.384 0.304 857.61 1.266 0.274 841.71 1.186 0.238 839.49
0.544 1.615 0.352 838.28 1.479 0.304 800.66 1.35 0.274 786.3 1.274 0.24 784.32
0.6498 1.696 0.325 724.34 1.555 0.281 692.46 1.414 0.25 675.16 1.345 0.22 673.44
0.7608 1.722 0.237 515.06 1.586 0.208 496.9 1.441 0.184 483.34 1.377 0.157 471.21
0.8774 1.724 0.12 260.02 1.591 0.104 248.83 1.447 0.093 243.98 1.395 0.076 231.03
1.0000 1.73 0 0 1.602 0 0 1.456 0 0 1.424 0 0
Diethyl malonate + m-xylene
0.0000 0.555 0 0 0.522 0 0 0.493 0 0 0.469 0 0
0.0825 0.74 0.088 472.99 0.68 0.069 423.02 0.635 0.063 407.75 0.596 0.048 371.23
0.1683 0.93 0.177 793.77 0.858 0.154 762.6 0.785 0.13 707.73 0.733 0.103 655
0.2575 1.13 0.272 1021.78 1.039 0.239 989.05 0.954 0.213 956.34 0.884 0.169 879.72
0.3504 1.295 0.328 1093.74 1.187 0.287 1057.89 1.084 0.254 1021.68 1.017 0.213 971.64
0.4473 1.433 0.352 1068.98 1.311 0.306 1031.7 1.199 0.276 1008.74 1.137 0.241 979.29
0.5483 1.555 0.356 986.74 1.422 0.308 950.82 1.297 0.276 927.99 1.238 0.245 907.81
0.6537 1.651 0.328 839.19 1.511 0.283 807.27 1.375 0.252 786.17 1.317 0.224 766
0.764 1.692 0.239 590.45 1.557 0.21 573.44 1.415 0.186 557.6 1.358 0.159 531.52
0.8793 1.71 0.122 297.23 1.578 0.106 287.36 1.435 0.095 280.83 1.387 0.078 261.8
1.0000 1.73 0 0 1.602 0 0 1.456 0 0 1.424 0 0
Diethyl malonate + p-xylene
0.0000 0.577 0 0 0.551 0 0 0.505 0 0 0.492 0 0
0.0827 0.768 0.096 473.89 0.716 0.078 425.56 0.65 0.066 409.14 0.624 0.055 374.79
0.1687 0.964 0.193 797.81 0.899 0.171 763.36 0.802 0.137 708.82 0.764 0.115 656.99
0.2581 1.166 0.291 1022.1 1.084 0.262 990.36 0.973 0.223 957.19 0.918 0.185 882.3
0.3511 1.332 0.35 1094.5 1.232 0.312 1057.98 1.103 0.264 1021.82 1.051 0.232 972.78
0.448 1.469 0.375 1070.01 1.354 0.332 1032.1 1.218 0.287 1010.11 1.17 0.26 981.11
0.549 1.588 0.378 988.2 1.461 0.333 951.95 1.314 0.287 929.02 1.268 0.264 909.89
0.6544 1.678 0.346 839.45 1.543 0.304 808.05 1.389 0.262 787.44 1.341 0.239 766.61
0.7645 1.712 0.254 591.76 1.58 0.226 574.2 1.425 0.193 557.96 1.375 0.17 531.68
0.8796 1.721 0.13 298.1 1.59 0.115 287.39 1.441 0.1 282.18 1.397 0.085 263.46
1.0000 1.73 0 0 1.602 0 0 1.456 0 0 1.424 0 0

Table 3: Viscosity, η (m Pa s), deviation in viscosity, Δη (m Pa s) and excess Gibbs free energy of activation of viscous flow, ΔG*E (Jmol-1) for the binary mixtures of diethyl malonate and isomeric xylenes at various temperatures

Property Temp (K) A0 A1 A2 A3 A4 σ
Diethyl malonate + o-xylene
Δη (m Pa s) 303.15 1.4137 -0.0236 0.2506 0.2247 -1.1151 0.0077
308.15 1.225 0.0259 0.3229 0.0528 -1.2314 0.0057
313.15 1.1038 0.0407 0.1659 0.0183 -0.9088 0.0069
318.15 0.9739 -0.0597 -0.2052 0.1073 -0.46 0.0042
ΔG*E (Jmol-1) 303.15 3465.29 1253.547 1370.517 471.6292 -2093.47 13.6779
308.15 3307.13 1293.438 1648.547 46.7655 -2884.83 12.0507
313.15 3249.124 1273.93 1323.686 0.4554 -2381.6 17.9204
318.15 3270.533 1110.997 395.3116 61.7989 -1486.61 10.1959
Diethyl malonate + m-xylene
Δη (m Pa s) 303.15 1.4268 -0.0539 0.2302 0.2311 -1.0576 0.0078
308.15 1.2339 0.0043 0.3129 0.0502 -1.179 0.0054
313.15 1.1127 0.0198 0.1582 0.0199 -0.8612 0.0069
318.15 0.9873 -0.0972 -0.2063 0.1445 -0.4366 0.0045
ΔG*E (Jmol-1) 303.15 4120.746 1740.811 1707.524 758.8105 -1968.94 15.2292
308.15 3960.967 1800.282 2018.676 212.267 -2892.19 12.0754
313.15 3876.974 1750.618 1695.694 129.119 -2486.33 19.1586
318.15 3799.511 1470.171 587.1788 233.1599 -1372.62 11.5816
Diethyl malonate + p-xylene
Δη (m Pa s) 303.15 1.517 -0.028 0.2076 0.2096 -1.0199 0.0068
308.15 1.3352 0.0363 0.3368 0.0291 -1.2142 0.0055
313.15 1.1558 0.0257 0.2 0.0019 -0.9231 0.0074
318.15 1.0615 -0.0761 -0.2174 0.1295 -0.4061 0.0046
ΔG*E (Jmol-1) 303.15 4127.674 1735.429 1671.676 742.463 -1909.63 13.834
308.15 3965.943 1787.299 2015.433 238.7783 -2868.52 12.3211
313.15 3885.783 1739.739 1669.768 124.6681 -2434.53 19.3599
318.15 3808.254 1469.713 567.8503 234.8453 -1293.3 12.192

Table 4: Redlich-Kister coefficients Ai-1 and corresponding standard deviations (σ) computed for excess/deviation properties of the binary mixtures of diethyl Malonate + isomeric xylenes (o-xylene, m-xylene, p-xylene) at various temperatures

Viscosity deviation

The value and magnitude of Δη depend on molecular size and shape of the components in addition to intermolecular forces. It is observed (Table 3) that deviation in viscosity is positive for all the systems (DEM+OX/MX/PX) and at all the temperatures. The absolute value of viscosity deviation of (DEM+OX/MX/PX) systems builds directly and scopes to a greatest incentive at x1 ~ 0.5440 for (DEM+OX), x1 ~ 0.5483 for (DEM+MX), x1 ~ 0.5490 for (DEM+PX), after which step by step diminishes until pure condition of diethyl malonate is arrived. By and large, negative estimations of Δη demonstrate the presence of dispersion forces or mutual loss of specific interactions in molecules working in the systems and positive estimations of deviation in viscosity show solid particular collaborations [18-21]. As indicated by Kauzmann and Eyring [22], the viscosity of a mixture unequivocally relies upon the entropy of mixture, which is connected with the structure of the liquid. Vogel and Weiss [23] clarified that mixtures with solid communications between various molecules and negative deviations from Raoult’s law display positive viscosity deviations while for mixtures with positive deviations of Raoult’s law and without particular connections, the viscosity deviations are negative.

The less positive Δη esteems for diethyl malonate + o-xylene system show that associations are weaker over diethyl malonate + m-xylene and diethyl malonate + p-xylene systems [24], which recommends that the position of –CH3 groups on the aromatic ring assumes a generous part in choosing the extent Δη and, thus, the order of collaboration between the component molecules of the mixtures. The stereo normality of methyl groups in o-xylene is such that the steric repulsion is more. So that the Δη esteems for o-xylene are observed to be lower than the m-xylene and p-xylene. On account of p-xylene, the two methyl groups disperse similarly the π-electron cloud on the benzene ring, in this manner the charge transfer complex development between diethyl malonate and p-xylene brings about higher positive Δη esteems. The diethylmalonate + p-xylene mixtures are described by more positive Δη esteems than the mixtures of diethylmalonate + m-xylene and diethylmalonate + o-xylene, regardless of the way that p-xylene very nearly a zero dipole moment and thus dipole-induced dipole associations are not anticipated. One conceivable explanation behind this could be that p-xylene molecule is planar and flat type and can shape closer and parallel n-π complexes with slightest steric hindrance. The Δη esteems diminish with increment of temperature for all the three systems. This might be clarified as takes after: viscosity is principally the force exhibited by one layer of molecules on the neighboring layer of molecules. With the temperature rise, the cluster breakage causes weak associations and hence less force is exhibited on the adjacent layers which bring about the bringing down of deviation in viscosities. In this manner, the molecular communication follows the order:

DEM+OX<DEM+MX<DEM+PX

Excess Gibbs free energy of activation of viscous flow

The excess Gibbs free energy of activation of viscous flow like viscosity deviation can be utilized to detect molecular communications [25]. The excess Gibbs free energy of activation of viscous flow is positive for (DEM+OX/MX/PX) systems over the whole composition range and at all the temperatures. This shows the nearness of appealing strengths between the constituent molecules in the binary mixtures under examination. ΔG*E values diminishes with temperature ascend for all the three systems. This shows the debilitating of intermolecular communications at hoisted temperatures [26] and this is might be credited to detachment of related molecules through breakage of clusters both in the mixtures and immaculate solvents.

Analysing viscosity of fluid mixtures by semi observational models

In this article, we utilize the conditions of Grunberg-Nissan, Katti-Chaudhri, Heric-Brewer, Hind et al. furthermore, McAllister four body models to connect the viscosities of binary mixtures of (DEM+OX/MX/PX). Experimental and computed estimations of viscosity (η) for the binary mixtures of (DEM+OX/MX/PX) at 303.15 K are displayed in Table 5. Interaction (adjustable) Parameters computed from equations 2-6 and the relating standard deviations (σ) for all the binary mixtures are appeared in Table 2. An examination of information in Table 5 demonstrates that all the observational relations gave a sensible fit, but the viscosity values computed utilizing McAllister 4 body models are in great concurrence with the experimental values. Examination of information in Table 2 demonstrates that the estimations of interaction parameters (d) computed from various viscosity theories are positive for the systems: (DEM+OX/MX/PX) at the four distinct temperatures.

303.15 K
x1 η Expt η GN η KC η HB η H η Mc
Diethyl malonate + o-xylene
0.0000 0.706 0.706 0.706 0.706 0.706 0.706
0.0812 0.875 0.85 0.85 0.849 0.888 0.873
0.1658 1.051 1.009 1.009 1.008 1.06 1.036
0.2542 1.236 1.181 1.181 1.18 1.218 1.188
0.3465 1.387 1.356 1.357 1.355 1.362 1.324
0.443 1.509 1.525 1.525 1.524 1.488 1.441
0.544 1.615 1.672 1.673 1.673 1.593 1.54
0.6498 1.696 1.783 1.783 1.784 1.674 1.624
0.7608 1.722 1.838 1.838 1.84 1.727 1.69
0.8774 1.724 1.823 1.824 1.825 1.748 1.731
1.0000 1.73 1.73 1.73 1.73 1.73 1.73
Diethyl malonate + m-xylene
0.0000 0.555 0.555 0.555 0.555 0.555 0.555
0.0825 0.74 0.703 0.704 0.703 0.754 0.738
0.1683 0.93 0.875 0.876 0.874 0.941 0.933
0.2575 1.13 1.067 1.067 1.066 1.115 1.123
0.3504 1.295 1.271 1.27 1.27 1.273 1.297
0.4473 1.433 1.472 1.471 1.472 1.413 1.443
0.5483 1.555 1.653 1.651 1.653 1.532 1.556
0.6537 1.651 1.79 1.787 1.791 1.627 1.638
0.764 1.692 1.86 1.859 1.862 1.695 1.691
0.8793 1.71 1.843 1.844 1.845 1.731 1.72
1.0000 1.73 1.73 1.73 1.73 1.73 1.73
Diethyl malonate + p-xylene
0.0000 0.577 0.577 0.577 0.577 0.577 0.577
0.0827 0.768 0.73 0.731 0.729 0.781 0.767
0.1687 0.964 0.906 0.907 0.905 0.973 0.966
0.2581 1.166 1.102 1.102 1.101 1.149 1.16
0.3511 1.332 1.308 1.307 1.307 1.309 1.334
0.448 1.469 1.51 1.508 1.509 1.449 1.479
0.549 1.588 1.688 1.685 1.688 1.565 1.589
0.6544 1.678 1.819 1.817 1.821 1.656 1.665
0.7645 1.712 1.881 1.88 1.883 1.717 1.711
0.8796 1.721 1.854 1.855 1.855 1.743 1.731
1.0000 1.73 1.73 1.73 1.73 1.73 1.73

Table 5: Experimental and computed estimations of viscosity, η (m Pa s) for the binary mixtures of diethyl malonate + o-xylene, diethyl malonate + m-xylene, diethyl malonate + p-xylene at 303.15 K

As indicated by Fort and Moore [27], G12 is dealt with as a precise estimation to discover the quality of association between the components. On the off chance that G12 is positive, at that point the system shows property of solid connection, on the off chance that it is negative; it is having the property of feeble communication. So also, Nigam and Mahl [28] inferred that: (i) If Δη > 0, G12 > 0 and the magnitudes of the above are large then solid particular cooperation’s would happen; (ii) If Δη < 0, G12 > 0 then feeble associations would exist; (iii) If Δη < 0, G12 < 0 and the extents of both are huge then the dispersion force would be predominant. In the present binary systems (DEM+OX/MX/PX), G12 esteems in the Table 5 are positive and viscosity deviation is positive (Δη > 0) consequently one could state that solid particular cooperation’s would display in the present binary mixtures.

Conclusion

From the estimations of viscosity and density, deviation in viscosity and excess Gibbs free energy of activation of viscous flow are computed. The exploratory estimations of viscosity were associated with the semi exact relations of viscosity like Grunberg-Nissan, Katti-Chaudhri, Heric-Brewer, Hind et al., and McAllister four body models. Among the entire relations McAllister four body model gave great concurrence with the experimental values. From the watched positive estimations of Δη, ΔG*E and G12 interaction parameter, it is presumed that strong molecular interactions are available among the concentrated binary mixtures.

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