Study of intermolecular interactions in binary mixtures of methyl acrylate with benzene and methyl substituted benzenes at different temperatures:An experimental and theoretical approach

Anil Kumar Nain

Department of Chemistry,Dyal Singh College (University of Delhi),New Delhi 110 003,India

Keywords:Ultrasonic speed Viscosity Methyl acrylate Aromatic hydrocarbon Excess properties Intermolecular interactions

ABSTRACT The ultrasonic speeds, u and viscosities,η of the binary mixtures of methyl acrylate with benzene,toluene,o-xylene,m-xylene,p-xylene,and mesitylene over the whole mole fraction range were measured at six different temperatures and at atmospheric pressure.From the experimental data,the excess isentropic compressibility,,excess ultrasonic speed, uE,excess molar isentropic compressibility,excess specific impedance,ZE and deviations in viscosity,Δη have been calculated.The partial molar isentropic compressions,and,and excess partial molar isentropic compressions,andover the whole composition range,partial molar isentropic compressions,and,and excess partial molar isentropic compressions,andof the components at infinite dilution have also been calculated.The results specified the existence of weak interactions between unlike molecules,and these interactions follow the order:benzene >toluene > p-xylene > m-xylene > o-xylene >mesityle ne.The magnitude of interactions was found to be dependent on the number and position of the methyl groups in these aromatic hydrocarbons.

1.Introduction

The knowledge of physicochemical properties of binary liquid mixtures has significance in theoretical and applied areas of research and these results are frequently used to design processes(flow,mass transfer or heat transfer calculations) in many chemical and industrial applications [1,2],and the properties like ultrasonic speed,viscosity and parameters derived from these,can be used as important tools for probing interactions between component of liquid mixtures [3–6].The ultrasonic speed can be considered as a thermodynamic property,provided that a negligible amount of ultrasonic absorption of the acoustic waves of low frequency and of low amplitude is observed [7].In continuation to our ongoing research on non-aqueous liquid mixtures[8–12],here the results of ultrasonic and viscometric studies are reported for the binary mixtures of methyl acrylate (MA) with benzene and methyl substituted,viz.,benzene,toluene,o-xylene,m-xylene,pxylene and mesitylene at different temperatures.

MA is a very important industrial solvent and is extensively used commercially in the production of technically important high polymeric and latex compounds.It is relatively polar (dipole moment,μ=1.77 D at 298.15 K,1 D=3.334×10-3°C?m)[13],aprotic and unassociated liquid.The aromatic hydrocarbons possess large quadrupole moments [14],instigating an orientational order among molecules due to the partial alignment of neighbouring segments or of whole molecules[14].Acrylates are frequently used in many applications such as leather,textiles,adhesives,paints,antioxidant agents,inks,amphoteric surfactants,paper,detergents,surface coatings,etc.[12].Also,the liquid mixtures containing aromatic hydrocarbons find applications in the studies of polymer phase diagrams and preferential interaction in mixed media [15].Therefore,the mixtures of MA with aromatic hydrocarbons will be highly useful in many chemical and industrial applications.MA due to lone electron pairs possess electron-donor ability [16]towards the aromatic rings which act like electron-acceptors [17]and may involve in charge-transfer interactions which may be influenced by the presence of alkyl groups on the ring.A survey of literature shows that there exist some studies [3–6,18,19] on mixtures of alkyl acrylates with other organic liquids from the point of view of their ultrasonic and viscometric behaviour.

The present paper reports ultrasonic speeds,uand viscosities,η of MA+benzene,+toluene,+o-xylene,+m-xylene,+p-xylene,and +mesitylene binary mixtures covering the entire composition range,expressed by the mole fraction,x1of MA at 293.15,298.15,303.15,308.15,313.15,and 318.15 K and atmospheric pressure.The density,ρ data for the present work are taken from our earlier study [8].From the experimental data,the excess isentropic compressibility,,excess ultrasonic speed,uE,excess molar isentropic compressibility,,excess specific impedance,ZEand deviations in viscosity,Δη have been calculated.The partial molar isentropic compressions,and,and excess partial molar isentropic compressions,andover the whole composition range,partial molar isentropic compressions,andand excess partial molar isentropic compressions,andof the components at infinite dilution have also been calculated.The variation of these parameters with composition and temperature are deliberated in terms of intermolecular interaction in these mixtures.

2.Experimental

Methyl acrylate and the aromatic hydrocarbons (benzene,toluene,o-xylene,m-xylene,p-xylene,and mesitylene,mass fraction purities >0.99) were products from Spectrochem Pvt.Ltd.,India and were purified by using standard methods [13,20].The mass fraction purities of the purified chemicals have been estimated by gas chromatography.The final purities and other specifications of the chemicals used are given in Table 1.The purified chemicals were stored over 0.4 nm molecular sieves for 72 h to remove water,if any,and were degassed at low pressure prior to use.The mixtures were prepared by mass and weighings were done by using an electronic balance(model:GR-202R,AND,Japan)with a precision of±0.01 mg.The uncertainty in the mole fraction was estimated to be within ± 0.0001.

The ultrasonic speeds in pure liquids and in their binary mixtures were measured using a single-crystal variable-path multifrequency ultrasonic interferometer(Mittal Enterprises,India,Model:M81S) operating at 3 MHz.The uncertainty in ultrasonic speed measurements was within ± 0.5 m?s-1.The viscosities of the test samples were measured by using Ubbelohde type suspended level viscometer.The viscometer was calibrated with triply distilled water.The viscometer containing the test liquid was allowed to stand for about 30 min in a thermostatic water bath to minimize the thermal fluctuations inside the viscometer.The time of flow was taken in triplicate with a digital stopwatch having an accuracy of ± 0.01 s.The uncertainty in viscosity measurements was estimated to be within ± 1%.

The temperature of the test liquids throughout the measurements was controlled to an uncertainty of ± 0.1 K in an electronically controlled thermostatic water bath (JULABO,Model:ME-31A,Germany).The consistency of measureduand η data was ascertained by comparing the data of pure liquids with the corresponding literature data (the comparison is presented in Table S1 along with literature references,given as Supplementary Material )and the agreement between the values obtained here with the literature is found good,except few deviations.

3.Results and Discussion

The experimental values of ultrasonic speeds,uand viscosities,η of binary mixtures of MA with benzene,toluene,o-xylene,mxylene,p-xylene,and mesitylene over whole composition range at the investigated temperatures are listed in Tables 2 and 3,respectively.

Table 1 Specification of chemical samples

Table 2 Ultrasonic speeds, u (m?s-1) as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures T=(293.15 318.15) K and pressure, p=101 kPa

Table 2 (continued)

Table 3 Viscosities,η(10-3?N?s?m-2)as function of mole fraction,x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures,T=(293.15–318.15)K and pressure,p=101 kPa

Table 3 (continued)

Table 4 Excess isentropic compressibilities,1010/m2?N-1 as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures, T=(293.15–318.15) K

Table 4 Excess isentropic compressibilities,1010/m2?N-1 as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures, T=(293.15–318.15) K

Table 4 (continued)

Table 5 Excess ultrasonic speeds,10-2uE/m?s-1 as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures, T=(293.15–318.15) K

Table 5 (continued)

3.1.Excess parameters

whereVmis the molar volume;φ is the volume fraction;is the molar volume of the ideal mixture;αpis the isobaric expansivity,is the isobaric expansivity of the ideal mixture;Cpis the molar isobaric heat capacity;andis the molar isobaric heat capacity of the ideal mixture.The values of φi,Vm,andare calculated using the relations

whereMis the molar mass.The values of αpare calculated using the temperature dependence of the density data[8]of pure liquids utilizing the relation,(–1/ρ)(?ρ/?T)p)andCpvalues for the pure liquids(at studied temperatures) were calculated by means of group contribution method[24].The values ofCpfor the pure liquids at studied temperatures are given in Table S2 given as Supplementary Material .

wherenis the number of data points andjis the number ofAicoefficients(j+1 in the present study).The coefficients,Aiand standard deviations,σ of fit for these mixtures are recorded in Table 9.The variations of,ZEand Δη withx1,along with smoothed values from Eq.(16) are presented graphically in Figs.1–5 at 298.15 K and in Figs.S1 -S5 (given as Supplementary Material )at each investigated temperature,respectively.

Table 6 Excess molar isentropic compressions,/m5?N-1?mol-1 as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures, T=(293.15–318.15)K

Table 6 Excess molar isentropic compressions,/m5?N-1?mol-1 as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures, T=(293.15–318.15)K

Table 6 (continued)

Table 7 Excess specific acoustic impedances,105ZE/kg?m-2?s-1 as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures, T=(293.15–318.15) K

Table 7 (continued)

Table 8 Deviations in viscosity,104Δη/N?s?m-2 as function of mole fraction, x1 of MA for MA+aromatic hydrocarbon mixtures at the temperatures, T=(293.15–318.15) K

Table 8 (continued)

Table 9 Coefficients, Ai from Eq.(16) for the excess properties and standard deviations,σ for methyl acrylate+aromatic hydrocarbon mixtures at temperatures, T=(293.15-318.15) K

Table 9 (continued)

Table 9 (continued)

The results presented in Figs.1 and S1 indicate thatvalues are negative for MA+benzene/toluene/o-xylene/m-xylene/pxylene and positive for MA+mesitylene mixtures over entire mole fraction range at all investigated temperatures.The magnitude of deviations in(Fig.1) follows the order:benzene toluene >p-xylene >m-xylene >o-xyl ene>mesitylene.Similar type of donor–acceptor interactions have also reported by Maet al.[27],between oxygen atom of sulpholane and π-electrons of the aromatic hydrocarbons and by Aliet al.[28],between oxygen atom of dimethyl sulfoxide and π-electrons on the ring of the aromatic hydrocarbons.

The steric hindrance due to substituted-CH3groups in the ring can be another reason that may lead to an increase invalues.With increase in the number of methyl group substituted at the ring from benzene to mesitylene,the closer approach of MA molecule to the aromatic ring becomes gradually difficult as shown in Fig.6,resulting in reduced interaction between MA and aromatic hydrocarbon molecules.The schematic representation of interaction in Fig.6 clearly indicates that the approach of MA molecules to benzene ring is hindered by presence and number of -CH3groups at various positions.Also,among the xylenes the magnitude of negativevalues follow the order:o-xylene

It is observed that the values ofincrease with increase in the temperature of the mixture(Fig.S1) for all the six binary systems.The increase inis ascribed to the disruption of donor–acceptor interactions between unlike molecules with rise in temperature,leading to an expansion in volume,and hence,causing an increase invalues.

A perusal of Figs.2 and S2 indicate that theuEvalues are positive for MA+mesitylene and negative for MA+benzene/toluene/oxylene/m-xylene/p-xylene mixtures over entire mole fraction range and investigated temperature range.In general,the positiveuEvalues are observed due to presence of significant interactions,while negativeuEvalues due to weak interactions between the unlike molecules in the mixture [30,31].The observed positiveuEvalues for MA+benzene/toluene/o-xylene/m-xylene/p-xylene mixtures indicate specific interactions,while the negativeuEvalues for MA+mesitylene mixtures indicate weak interactions between unlike molecules.The magnitude ofuEvalues for these mixtures follow the order:benzene >toluene >p-xylene >mxylene >o-xylene >mesitylene,which also replicates the order of MA-aromatic hydrocarbon interactions.It is observed that theuEvalues decrease with increase in temperature of the mixture(Fig.S2) for all these systems.The decrease inuEis ascribed to the breaking of donor–acceptor interactions between unlike molecules with rise in temperature,leading to decrease in compactness of the system,hence,resulting in a decrease inuEvalues.

Figs.3 and S3 indicates thatvalues are negative for MA +benzene/toluene/o-xylene/m-xylene/p-xylene and positive for MA+mesitylene mixtures over entire mole fraction range and investigated temperature range.The magnitude of deviations in(Fig.3) follow the order:benzene

A perusal of Figs.4 and S4 indicates that theZEvalues are positive for MA+benzene/toluene/o-xylene/m-xylene/p-xylene and negative for MA+mesitylene mixtures over entire mole fraction range and investigated temperature range.In general,the positiveZEvalues indicate the existence of significant interactions,while negative values ofZEindicate weak interactions between unlike molecules in the mixtures [32].The observed positiveZEvalues for MA+benzene/toluene/o-xylene/m-xylene/p-xylene mixtures indicate specific interactions,while negativeZEvalues for MA+mesitylene mixtures indicate weak interactions between unlike molecules in these mixtures.The magnitude ofZEvalues for these mixtures follow the sequence:benzene >toluene >p-xylene >mxylene >o-xylene >mesitylene,which also replicates the order of MA-aromatic hydrocarbon interactions.The values ofZEdecrease with increase in the temperature of the mixture (Fig.S4) for all the six binary systems.The decrease inZEis attributed to the disruption of donor–acceptor interactions with rise in temperature,leading to an expansion in the free volume,and hence resulting in a decrease inZEvalues.Thus,the observed trends ofZEstrongly support the behaviours offor these mixtures.

Figs.5 and S5 indicate that Δη values are positive for MA+benzene and negative for MA+toluene/o-xylene/m-xylene/p-xylene/mesitylene mixtures over entire mole fraction range and studied temperature range.The observed positive Δη values for MA+benzene mixtures indicate specific interactions between the component molecules and negative values of Δη for MA+toluene/oxylene/m-xylene/p-xylene/mesitylene mixtures indicate the presence of weak interactions between the component molecules[33].Also,the magnitudes of Δη values (Fig.5) at equimolar composition of these mixtures follow the order:benzene>toluene>pxylene >m-xylene >o-xylene >mesitylene,which also replicates the order of MA-aromatic hydrocarbon interactions in the same manner.Fig.S5 indicates that Δη values decrease with rise in the temperature for all these systems.The decrease in Δη is attributed to the breaking of donor–acceptor interactions with rise in temperature,resulting in a decrease in Δη values.Thus,these observed trends of Δη further strengthens the conclusions drawn from the trends ofZEand[8]regarding interactions prevalent in these mixtures.

3.2.Partial molar isentropic compressions

Fig.1.Excess isentropic compressibility, vs. volume fraction,φ1 of MA for the binary mixtures at T=298.15 K.◆,MA+benzene;■,MA+toluene;▲,MA + oxylene;●,MA + m-xylene;□,MA + p-xylene;Δ,MA+mesitylene;—,calculated from Eq.(16).

Fig.2.Excess ultrasonic speeds, uE vs. mole fraction, x1 of MA for the binary mixtures at T=298.15 K.□,MA+benzene;■,MA+toluene;▲,MA+o-xylene;●,MA+m-xylene;□,MA+p-xylene;Δ,MA+mesitylene;—,calculated from Eq.(16).

Fig.3.Excess molar isentropic compressibility, vs. mole fraction, x1 of MA for the binary mixtures at T=298.15 K.◆,MA+benzene;■,MA+toluene;▲,MA+oxylene;●,MA + m-xylene;□,MA + p-xylene;Δ,MA+mesitylene;—,calculated from Eq.(16).

Fig.4.Excess specific acoustic impedance, ZE vs. mole fraction, x1 of MA for the binary mixtures at T=298.15 K.◆,MA+benzene;■,MA+toluene;▲,MA + oxylene;●,MA + m-xylene;□,MA + p-xylene;Δ,MA+mesitylene;—,calculated from Eq.(16).

Fig.5.Deviations in viscosity,Δη vs.mole fraction,x1 of MA for the binary mixtures at T=298.15 K.◆,MA+benzene;■,MA+toluene;▲,MA+o-xylene;●,MA+mxylene;□,MA + p-xylene;Δ,MA+mesitylene;—,calculated from Eq.(16).

3.3.Correlating models for viscosity

Several semi-empirical models [39–47] were used to estimate the viscosities of the mixtures theoretically from data of pure components.The semi-empirical models applied to the systems under study are as follows

Grunberg-Nissan [39] model

Hind,McLaughlin and Ubbelohde [40] model

Katti and Chaudhri [41] model

Heric and Brewer [42,43] 2-parameter model

McAllister [45] (3-body interactions) model

Heric and Brewer [42,43] 3-parameter model

McAllister [45,46] (4-body interactions) model

Fig.6.Schematic presentation of interactions in the methyl acrylate (MA)+aromatic hydrocarbon mixtures,(a) MA+benzene,(b) MA+toluene,(c) MA + o-xylene,(d)MA + m-xylene,(e) MA + p-xylene and (f) MA+mesitylene.

Fig.7.Variation of excess partial molar isentropic compressions, and of(a) MA and (b) aromatic hydrocarbons,respectively,of against mole fraction, x1 of MA for the binary mixtures at T=298.15 K,◆,MA+benzene;■,MA+toluene;▲,MA + o-xylene;●,MA + m-xylene;□,MA + p-xylene;Δ,MA+mesitylene.

Auslander [47] model

The terms and notation used in the relations (24)–(32) are the same as given in the literature [39–47].The values of the parameters of the Eqs.(24)–(32),evaluated by using least-squares method,and those of their standard deviations,σ and average percentage deviations (APDs) obtained by using experimental viscosity data,as described by Heric and Brewer [43],are given in Table 11.

The analysis of the results for one-parameter relations reveals that APD values (Table 11) are in the range 0.0131% to 0.0389%for MA+benzene,0.0406% to 0.0659% for MA+toluene,0.0772%to 0.0961% for MA +o-xylene,0.0383% to 0.0858% for MA +mxylene,0.012% to 0.0399% for MA +p-xylene,and 0.0468% to 0.2025% for MA+mesitylene binary mixtures.The analysis of the results of Eqs.(24)–(26)indicates that all the one-parameter models predict the viscosity data well,with Hindet al.model showing minimum APD values,followed by the other two models for the binary system.

For 2-parameter relations,the APD values (Table 11) are in the range 0.0133%to 0.033%for MA+benzene,0.0379%to 0.0392%for MA+toluene,0.0705% to 0.0783% for MA +o-xylene,0.0401% to 0.0408% for MA +m-xylene,0.0124% to 0.0141% for MA +pxylene,and 0.0118% to 0.0519% for MA+mesitylene binary mixtures.The analysis of the results of Eqs.(27)–(29) indicates that all the 2-parameter models predict the viscosity data well,with Heric-Brewer and McAllister models exhibiting low APD values,followed Lobe relation showing slightly larger values of APD for these systems.

For 3-parameter relations,the APD values (Table 11) are in the range 0.0042% to 0.0126% for MA+benzene,0.0057% to 0.0504%for MA+toluene,0.0079% to 0.077% for MA +o-xylene,0.0056%to 0.0212% for MA +m-xylene,0.0058% to 0.0320% for MA +pxylene,and 0.0088% to 0.1922% for MA+mesitylene binary mixtures.The analysis of the results from Eqs.(30)–(32)indicates that all the 3-parameter models predict the viscosity data very well,with McAllsiter (4-body interaction) and Heric-Brewer (3-parameter) models predicting the viscosity data better than Auslander model for these binary mixtures.

The values of APDs for all the binary systems under study(Table 11) indicate that for each system 3-parameter models predict the data best trailed by 2-parameter models,and then by one-parameter models.

Table 10 The values of for the components for methyl acrylate+aromatic hydrocarbon mixtures at temperatures, T=(293.15–318.15) K

Table 10 The values of for the components for methyl acrylate+aromatic hydrocarbon mixtures at temperatures, T=(293.15–318.15) K

3.4.Scaled particle theory

Scaled particle theory(SPT)is a statistical model[48,49],which considers liquid molecules as hard spheres.SPT does not necessitate the calculation of the entire radial distribution function to define of the equation of state for fluids[49].It relates microscopic parameters such as radius,surface area and hard-core volume of a molecule with the thermodynamics parameters such as volume,ultrasonic speed,compressibility,etc.[49],and considers the shapes of constituent molecules of a binary mixture in calculating their ultrasonic speed theoretically [50].In SPT [50] different shapes,such as spherical,cube,tetrahedral,disc A,disc B,disc C and disc D of the participating component molecules are considered and when the participating constituents have the suitable shapes their ultrasonic speed is calculated theoretically with minimum deviations.The SPT had been used by various researchers[50,51] for the binary mixtures of by considering different shapes.The equation of state of fluid in SPT is given as

where ρNis number densityNA/Vo,hereVois the ideal volume of the mixture,pis the pressure,η=VHρN,VHbeing hard core volume of the molecule,η is the hard core volume of molecules per unit volume andkBis the Boltzmann constant.The equation of state for mixture of hard convex molecules is as follows [48,49]

whereandSiare the mean radius of curvature and surface area,respectively,of a molecule of speciesi.The values ofR,SandVHfor various shapes are listed in Table 12.

The pressure derivative is related to ultrasonic speed as

where ρ is molecular density,and γ is the ratio of specific heats.Combining Eqs.(34) and (36),we get

Eq.(37) is used to evaluate the ultrasonic speed in the binary mixtures theoretically.In case of pure liquids,Eq.(37) is modified by including the dimensionless shape parameters,X=R-S/VHand η=VHρNas

Its solution is obtained as [50]

whereK=1+L（X-1）/2 andL=The mean radius and the surface area of a molecule can be written asandWhere the parametersYandZare related to the shape of the molecule.The values ofX,YandZhave been calculated for different shapes and are listed in Table 13.The calculated η values are given in Table 14.The theoretical ultrasonic speeds of these systems using SPT were computed for 49 combinations achieved by assuming different shapes,viz.,sphere,cube,tetrahedron,disc A,disc B,disc C and disc D,for the participating molecules.

Table 11 Values of parameters calculated from Eqs.(24)–(32) of viscosity models,along with the standard deviation,σ and average percentage deviations,APD between theoretical and experimental η values for MA+aromatic hydrocarbon binary mixtures at T=298.15 K

The best-fitting combination of shapes of participating molecules,which gives minimum deviations between experimental and theoretical values ofu,was obtained by calculating the average relative percentage deviations,σ(%)for all mole fractions,for each system at the temperatures,298.15,308.15 and 318.15 K are calculated by using the equation

whereuCalcis the theoretical ultrasonic speed,uExptis the experimental speed andnis the number of data points.The experimental and theoretically calculated ultrasonic speeds for these mixtures,having best-fitting combination of shapes of component molecules,at 298.15,308.15 and 318.15 K are given in Table 15.

Table 15 reveals that the shape of MA molecule is affected by both the presence/shape of other component in mixture and the temperature.The deviations between experimental and theoretically calculatedufor MA+benzene mixtures reveals that MA acquires disc A shape and benzene acquires tetrahedron shape at298.15 K;and MA acquires sphere shape and benzene acquires disc C shape at 308.15 K and MA acquires cube shape and benzene acquires tetrahedron shape at 318.15 K.For MA+benzene mixtures,the shape of MA and benzene molecules is affected by the temperature.The shape of MA molecule changes from disc A →sphere →cube while the shape of benzene molecule changes from tetrahedron →disc C →tetrahedron,when temperature is varied from 298.15 K →308.15 K →318.15 K.

Table 12 Molecular parameters for different shapes

Table 13 Shape parameters

For MA+toluene mixtures (Table 15),MA acquires cube shape and toluene acquires disc B shape at 298.15 K;and MA retains cube shape and toluene acquires tetrahedron shape at 308.15 and MA acquires sphere shape and toluene acquires cube shape at 318.15 K.For MA+toluene mixtures,the shape of MA and toluene molecules is affected by the temperature.The shape of MA molecule changes from cube to sphere to cube when temperature is varied from 298.15/308.15 K to 318.15 K,while the shape of toluene molecule changes from disc B →tetrahedron →cube,when temperature is varied from 298.15 K →308.15 K →318.15 K.

For MA +o-xylene mixtures (Table 15),MA acquires disc A shape ando-xylene acquires disc C shape at 298.15 K;and MA acquires disc B shape ando-xylene acquires tetrahedron shape at 308.15 and MA acquires disc A shape ando-xylene acquires cube shape at 318.15 K.For MA +o-xylene mixtures,the shape of MA ando-xylene molecules is affected by the temperature.The shape of MA molecule changes from disc A →disc B →disc A,while the shape ofo-xylene molecule changes from disc C →tetrahedron→cube,when temperature is varied from 298.15 K →308.15 K →318.15 K.

For MA +m-xylene mixtures (Table 15),MA acquires sphere shape andm-xylene acquires cube shape at 298.15 K;and MA acquires disc B shape andm-xylene acquires tetrahedron shape at 308.15/318.15 K For MA +m-xylene mixtures,the shape of MA andm-xylene molecules is affected by the temperature.The shape of MA molecule changes from sphere →disc B,while the shape ofm-xylene molecule changes from cube →tetrahedron,when temperature is varied from 298.15 K →308.15/318.15 K.

For MA+p-xylene mixtures(Table 15),MA acquires cube shape at 298.15/308 K andp-xylene acquires disc B shape at 298.15 K;pxylene acquires tetrahedron shape at 308.15 K;and MA acquiressphere shape andp-xylene acquires cube shape at 318.15 K.For MA +p-xylene mixtures,the shape of MA andp-xylene molecules is affected by the temperature.The shape of MA molecule changes from cube →sphere,when temperature is increased from 298.15/308.15 K →318.15 K,while disc B →tetrahedron →cube,when temperature is varied from 298.15 K →308.15 K →318.15 K.

Table 14 Values of η for all the various shapes for AN and acrylates at 298.15,308.15 and 318.15 K calculated from Eq.(39)

Table 15 Values of ultrasonic speeds,u(m?s-1)calculated using SPT for different behavioral shapes along with minimum average percentage deviation,σ(%)and experimentally measured values and for MA+aromatic hydrocarbon mixtures at temperature, T=(298.15,308.15 and 318.15) K

Table 15 (continued)

For MA+mesitylene mixtures(Table 15),both MA and mesitylene acquire tetrehedron shape at all the three investigated temperatures,i.e.,the shape of MA and mesitylene molecules is not affected by the change in temperature.The scaled particle theory(SPT)predicted the ultrasonic speed for all these mixtures satisfactorily and reasonably well,except for MA+mesitylene system for which large deviations are observed.The reason for large deviations in case of MA+mesitylene mixtures may be that the 7 shapes assigned to mesitylene molecule are not compatible with its structure.

4.Conclusions

The experimentaluand η values for methyl acrylate+benzene,+toluene,+o-xylene,+m-xylene,+p-xylene,and+mesitylene of binary mixtures have been measured at six different temperatures.The values ofandhave been calculated.The variation of these parameters with composition showed the existence of weak electron donor–acceptor type interactions between electronegative oxygen atoms of MA (acting as donor) and the π-electrons of ring of aromatic hydrocarbon molecules (acting as acceptor)in these mixtures and this interaction decreases with rise in temperature.The strength of interactions in these mixtures follows the order:benzene >toluene >p-xylene >m-xylene >o-xyl ene >mesitylene,which suggested that the interactions depend upon the number and position of methyl groups in these aromatic hydrocarbon molecules.It has been observed that all the investigated viscosity models correlate the viscosity data well for all the systems.The scaled particle theory predicted the ultrasonic speed for all these mixtures satisfactorily and reasonably well,except for MA+mesitylene system for which large deviations are observed.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary Material

Supplementary data to this article can be found online at https://doi.org/10.1016/j.cjche.2021.05.024.