Determination of thermodynamic properties of poly(cyclohexyl methacrylate)by inverse gas chromatogra

2014年7月语Vol 32 No. 7July 2014Chinese journal of Chromatography746~752ArticleDOI:10.3724/SPJ.1123.2014.04028Determination of thermodynamic properties of poly( cyclohexylmethacrylate)by inverse gas chromatographyIsmet KAYA, Cigdem Yigit PaLa(I. Canakkale Onsekiz Mart University, Faculty of Sciences and Arts, Department of Chemistry, PolymerSynthesis and Analysis Laboratory, Canakkale 17020, Turkey: 2. Kaleseramik AR-GE ResearchKaleseramikr&d Center, Kaleseramik Canakkale Kalebodur ceramicIndustries Inc, Canakkale 17020, TurkeyAbstract: In this work, some thermodynamic properties of poly( cyclohexyl methacrylate were studied bynverse gas chromatography( IGC ) For this purpose, the polymeric substance was coated on Chromosorb Wand which was filled into a glass column. The retention times(t,) of the probes were determined from theinteractions of poly( cyclohexyl methacrylate with n-pentane, n-hexane, n-heptane, n-octane, n-decanemethanol, ethanol, 2-propanol, butanol, acetone, ethyl methyl ketone, benzene, toluene and o-xylene by IGCtechnique. Then, the specific volume( Vp)was determined for each probe molecule. By using( I/T; InVg)graphics, the glass transition temperature of poly( cyclohexyl methacrylate )was found to be 373 K. The adsorp-tion heat under the glass transition temperature(AH ) and partial molar heat of sorption above the glass tran-sition( AHS), partial molar free energy of sorption( AG,)and partial molar entropy of sorption( AS,) belonging to sorption for every probe were calculated. The partial molar heat of mixing at infinite dilution( AH.partial molar free energy of mixing at infinite dilution(AG, ) Flory-Huggins interaction parameter(X%)andweight fraction activity coefficient(a,/w, ) values of polymer-solute systems were calculated at different column temperatures. The solubility parameters(8) of the polymer were obtained by IGC techniqueKey words: inverse gas chromatography( IGC ) poly( cyclohexyl methacrylate ) thermodynamic propertiesCLC number:0658 Document code: A Article IC: 1000-8713( 2014)07-0746-0The methacrylate polymers are widely used in ture 2 ] This method is of convenience and eco-the manufacture of prostheses, contact lenses, nomics of operation. The basic tools for IGC areadhesives, coatings, etc.[ 1 The thermodynam- inexpensive, rugged, widely available, and suitic properties and solubility of polymers are param able for routine laboratory applications. IGc dataeters that must be known for application of poly- might be collected quite rapidly over extendedmer synthesis, economic production of polymeric temperature ranges[ 3]. As the molecular weightsmaterials and the process that used for this pur- of the polymeric substances are very high and thepose. These parameters can be investigated with polymeric substances are non-volatile, IGC meththe inverse gas chromatography( IGC )technique. od has been used to investigate the properties ofIn this technique, the polymer is coated onto supthese substances instead of normal gas chromaported material and then filled into chromato- tography. IGC was developed by Smidsrod andgraphic columns The solvents with known prop- guillet[ 4 and applied to many polymeric sys-erties pass through the column by carrier gas and tems. The information in the processing steps ofleave the column at different times according to polymers are important parameters for higher polthe interest of the polymer. IGc technique has ym中国煤化工- namic of polymer sysbeen used for the determination of some propertecessing steps can bties of the polymers such as the solubility paramecanCNMHGknowledge of thermo-ters, melting point and glass transition temperadynamic data of polymer solutions is a necessity*CorrespondingauthorFax:+902862180533,E-mail:kayaismet@@hotmail.comReceived date: 2014-04-18第7期Ismet KAYA, et al: Determination of thermodynamic properties ofpoly( cyclohexyl methacrylate )by inverse gas chromatographyfor the inement of industrial proce6ln(V)6(1/T)=-△H/R(5)n this paper, we have examined the interacThe weight fraction activity coefficient, (a,/tions of poly( cyclohexyl methacrylate )with alco- w, ), the partial molar free energy( AG )andhols( polar )and alkanes( nonpolar ) acetone, the average partial molar heat of mixing( AHIethyl methyl ketone, benzene, toluene and o-xyite dilution were calculated according tolene solute probes by using IGc in the tempera- the following equations. Heats of vaporizationture range of 353-453 K. Flory-Huggins interac- (AH.) for the probes were obtained from thetion parameter(X12) and weight fraction activity heats of solution and heats of mixing by using thecoefficient(a/w,)of poly( cyclohexyl methac- following relation [9rylate )-solute systems selected were determined(a1/v1)=ln273.2R(PVM1)]by igc technique. Also, we have determined thP(B-V/RT)solubility parameter(8,) of the poly( cyclohexyl where b, is the second viral coefficient of themethacrylate )by IGC technique. The glass transi- ganic solute in the gaseous state; Po is the vaportion temperature(T,) of poly( cyclohexyl methpressure of the probes at the column temperatureacrylate )was found to be 373 and 371 K from IGC (T, K); M, is the molecular weight of the probeand differential scanning calorimetryVi is the molar volume of the solute. The values ofmeasurements, respectivelyP and B, have been calculated in literatures[101 Theoretical△G"=RT(a1/1)(7)The probe specific retention volume(V),cor△H=R8ln(a1/1)/8(1/T)](8)rected to o c was calculated from the standard△H、=△Hchromatographic relationThe molar volume of the solute( V,) was calVg=(AtXFX273 2)/(wxT r ).3/2(P/Po)2-1 culated using the following equation[ 11][(P1P0)3-1]V1=V。/qwhere At(=tp -tg) is the difference between the where V is the critical molar volume and q, is theretention times of the probe(t,) and the methane reduced density of the solute given by the follow(ts): F is the flow rate of the carrier gas meas- ing equationured at room temperature(T); w is the mass of Q.=1.20(5.565-11032.(1-TT)0. 8ie+o 3ithe polymeric stationary phase; Pi and Po are the(11)inlet and outlet pressures, respectively.where 2 is the critical compressibility factor andThe partial molar heat of sorption(AHi) and T is critical tethe partial molar free energy of sorption( AGS)ofThe Flory-Huggins parameter(Xu)characteri-the probe adsorbed by the polymer, is given by zing the interactions of a vapor-phase probe witEquation(2)and(3 )[5-8]a polymer is determined by Equation( 12△H=-R8lnV)/6(/T)]X2=ln273.2R2/(PVv1)]△G3=-RmnM1v(273.2R)](3)P(B1-V1)/(RT)](12)d(3 )we cal- where R is the gas constant; v, is the specific volculated the entropy of sorption of solutes as folume of the polymer.OwS中国煤化工e probe is calculated△S;=(△B-△G5)T(4)什HCNMHGThe adsorption heat of probes adsorbed by the61=[(△H-RT)V1(13)poly( cyclohexyl methacrylate )is given by the fowhere 8, is solubility parameter of probes: AH, islowing equation where AH is the adsorption en- the molar enthalpy of vaporization for the probe atthalpy and r is the ideal gas constant[9]temperature T(K)748第32卷The solubility parameter of the polymer(8,) ter at the end of the column. A flow rate of aboutcan be calculated by using the following equatio15 cm/min was used throughout our experiment6/(RT)-12/V1=[262/(RT)161-82/(RT)The glass tube( 2. 1 mx3. 2 mm i.d.)was washed(14) with acetone and was annealed prior to use. AIf the left hand side of this equation is plotted column packing material was prepared by coatingagainst 8, a straight line with a slope of 28,/RT 45-60 mesh size Chromosorb w treated with poly-and an intercept of (-82/RT) is obtained. The mer. An amount of 0. 5 g poly( cyclohexyl methacsolubility parameter of polymer(8,) can be deter- rylate )was dissolved in 100 mL of tetrahydrofumined from both the slope and intercept of the ran( THF ) An amount of 5 golid sup-straight line[ 15]. The studies indicated that the porting material was added to this solution andinverse gas chromatography method gives good kept stirring afterwards. The solvent was removedinformation on polymeric systems after careful by continuous stirring and slow evaporation underanalysis [ 9-12, 14, 16-18]. The Flory- Huggins in- partial vacuum in a rotary evaporator. The pre-teraction parameter(X%)and solubility parameter pared material was packed into the glass tubeof naphthenic and paraffinic base oils had 14, 16 J. The column was conditioned with fastbeen determined from Emam M.N. et al. by IGc carrier gas(N,,) flow rate for 48 h prior to usetechnique[ 19The probes were injected into the column with anauto sampler. Three consecutive injections were2 Experimentalmade for each probe at each set of measurement2.1 Materialsand three values of retention time with inverse gasFourteen polar and non-polar probes were used chromatography method were averaged. An injecin this study. They were selected to provide differ- tion volume was selected as 0. 1 uL. Methane wasent chemical natures and polarities. n-Pentane, n- synthesized in the laboratory by the reaction ofsodium acetate with sodium hydroxide[ 10].DScnol, ethanol, 2-propanol, butanol, acetone, ethyl analyses were carried out between 20-250C(inmethyl ketone, benzene, toluene and o-xylene, N2, 10 C/min ) using Perkin Elmer Pyris Sapwere from Aldrich Chemical Co. Poly( cyclohex,phire dscmethacrylate )was supplied by Across Organics in3 Results and discussionpowder form of Registry No. 1849402. Poly( cyclohexyl methacrylate was in white powderThe specific retention volumes (vo)of 14form.Refractive index( n20/D ) and density of po- probes were obtained by loading poly( cyclohexylly( cyclohexyl methacrylate ) were 1 506 5 and 1. 1 methacrylate)at a series of temperatures. ProbesmL at 25C, respectively Chromosorb W(45of different chemical natures and polarities( n-al-60 mesh ) was supplied from Sigma Chemical Co. kanes, alcohols, ketones, aromatics) were se2.2 Instrumentation and procedure of ther- lected for this study. The vg values of thesemodynamic studiesprobes were calculated according to Equation(1A Shimadzu GC-2010 model gas chromatograph and are given in Table 1 and Fig. 1, respectivelyequipped with a dual flame ionization detector The averages of three values of retention timewas used. Dried nitrogen gas( research grade) measured with inverse gas chromatography meth-was used as carrier gas. Methane was used as a O中国煤化工 of v. of each probe aton-interacting marker to correct the dead volume diffCNMH Glues changed with thein the column. Pressures at inlet of the column molecular weight of each group of solvents. Alsoread from gc were used to compute corrected re-poly(tention volumes by the usual procedure. Flow late )were decreased with increased temperaturerates were measured with a soap bubble flow me- According to IGc and DSc analyses, Tg of poly第7期Ismet KAYA, et al: Determination of thermodynamic properties ofpoly( cyclohexyl methacrylate )by inverse gas chromatography749Table 1 Variation of vw of selected organic solvent systems at different column temperaturesusing poly cyclohexyl methacrylate )as stationary phaseProbe353K63K373K83K393K403K423K433K443KK9.217.42n-Hexane10.329448.338.6610.408.407.637.72l3.83l1.2010.72n-Decane32.7923.824.1113.8912.62Methanol13.2ll.5610.248.987.4523.592-Prop14.4710.4372.1928.0218.1410.72EMK31.4915.009.2644.4910.Toluene52.6144.4732.4925.6120.1014.6412.9910.33O-Xylene106,7994.1266,453,4219.7216,32EMK: ethyl methyl ketonecyclohexyl methacrylate )was found as 100 and98℃, respectivelyfN-Pentane -v AcetoneThe (a/w,)and X values obtained usingHsplane-- BenzeneF7-Oe1a-lolusncEquation(6)and( 12 respectively are shown丹 Decane-- MethanolTable 2. The values of X 12 greater than 0. 5 represent unfavorable polymer-solvent interactionswhile values lower than 0. 5 indicate favorable inractions in dilute polymer solutions[ 17]. Thefollowing rules have been formulated by guillet eta2,)"<10: moderate solvents;( a/w, )">10: bacsolventsThe(a,/w,) data in Table 2 indicate that nT:(103K)pentane, acetone and benzene are good solvents:Fig.1 v# of selected probes at different temperaturesn-hexane, n-heptane, methanol, ethanol, 2Table 2 Polyd cyclohexyl methacrylate )-solute interaction coefficient(x 12)andactivity coefficients(a, /w, )of selected organic solvents at various temperatures433KK453K23K443KKPentane3.870.6180.743-0.872n-Hexane5,08n-Heptanen-Octane0.97013.44l1.62000.490L.434L.215Ethanol5.88TH0.2300.082中国煤化工CNMHG4.295,230,320.001benzene4.39Toluene6,145,290,4180.232o-Xylene8.677.717.180.8100.6780.6260.577750第32卷propanol, butanol, ethyl methyl ketone, toluene of the solutes showed dependence on the numberand o-xylene are moderate solvents; n-octane, n- of carbons in the series( except for alcoholsdecane are bad solvents for poly( cyclohexyl These values increased with increasing number ofmethacrylate ) Similar results were obtained ac- carbons in the series But in all series, the valuesording to the interaction parameters X 2 and AG of X2,(a/w,) and ag decreased with in-were found to be related to the number of carbons crease in the column temperature AG and AGin the series and temperaturecalculated from Equation(7 )and( 3 )respective-Xm, AGI,(a/,)and AH; at infinite dilution ly, are shown in Table 3Table 3( AG )i and AGi of sorption by using poly( cyclohexyl methacrylate )as thetationary phase and selected organie solvents as mobile phaseProbe423K433K383K403K1069.131036.9110142777.022820.912953.20n-Hexane1398.712579.292645.532755.23n-Heptane1861.301731,351690.511615,342396,442540.902180.322088.282026.21957.452179.002402.612363,442287,202207,471428.771500643.311654.611558.981495.33340Ethanol1524,451369,422761.862949,782-Propanol1395.491203.322663.95Butanol1701,281649,081573021857,782136.03Acetone384.581282.211240.59637.352798.472970.261484.612161.51297.41561.341502.81499,051802.891815.61757.21751.68879.591073.391344.82AHi values of probes at infinite dilution were values of probes were found according to equa-calculated using Eqation(8). In( a,/w,) were tion(9). Table 4 shows the experimentally ob-plotted against T"/K"( Fig. 2). AH, and AHS of tained sorption heats( AHS), molar heats of mix-poly( cyclohexyl methacrylate )-probe systems ing( AH )and adsorption heats( AH) in tem-were calculated by plotting In v. against T/K perature ranges of 353-373 K, 423-453 K and 353using Equation (5) and(2), respectively. AH373 K, respectively.-Pentane '.1-octancMethanoltoluene▲日- Decane22F·『 ethanol22F·mMK“a- Xylenei. Benzene2◆出anol2.07(10K)了;(10"K")r氵(10KFig 2 Variation of a,/w,)"with T-/K for( a )n-pentane, n-hexane, n-heptane, n-octane, n-decane;( b)methanolethanol, 2-propanol, butanol;( c)acetone, ethyl methyl kete中国煤化工yeneCNMHGThe number of carbon atoms of each probe isas or protH becomes more exothermic withdifferent from each other. AH becomes more ex- more CH, groups in each group probe. The attrac-thermic with increasing ch, groups in each tion forces between poly( cyclohexyl methacrygroup of probes due to the increasing surface are- late )and ketones are actually a combination of第7期Ismet KAYA, et al: Determination of thermodynamic properties ofpoly( cyclohexyl methacrylate )by inverse gas chromatography751two types: dispersive forces between the CH, reason, interactions between polymer and probesgroups of the ketones and the methyl group of are weakpoly( cyclohexyl methacrylate )and the interac-AHi values of n hydrocarbons changed fromtion of the c=o groups of the ketones with the 3.84 to 6.27 kcal/mol as seen from Table 4. AHc=o groups of poly( cyclohexyl methacrylate )via values of alcohols changed from 3. 88 to 5.39dipole-dipole interactions. Also, alcohols have kcal/mol, while the values of ketones changedhigher exothermic AH values than hydrocarbons, from 3. 40 to 3. 88 kcal/ mol and the values of aroketones and aromatics since there are hydrogen matics changed from 1.36 to 1.98 kcal/molbond interactions between poly( cyclohexyl meth- Based upon these results the probes with lowacrylate )and alcohols. AGI of these probes on AH values were accepted as solvent-polymer sys-poly( cyclohexyl methacrylate )are of positive val- tems and the others were taken as non-solventues. According to thermodynamic rules, AG is of polymer systemsnegative value for spontaneous events. For thisTable4△H`(383-403K),△H(423-453K),MH(353-373K),and△、 of selected organicsolvents on poly( cyclohexyl methacrylate△H△H,(keal/mol)kcal/molkcal/molkcal/molCalculated according to Equation(9)From Ref[13 1n-Pentanen-Hexane3.360.858.487.036.2Methanol9.972-Propanol5,016.6810.249,529.21AcetoneBenzene-6,67DiPaola-Baranyi et al[ 7] determined that AH 4.60, 4.18, 3. 74( cal/cm). and 5.17,4.38alues for aromatic solvents changed from -0.01 3.87, 3. 22( cal/cm2')> at 423, 433, 443 and 453kcal/ mol to 0. 3 kcal/ mol in polystyrene( PS ), K, respectively( Table 5)and from 0. 3 kcal/mol to 1. 1 kcal/mol in polymTable 5 Variation of 8, with poly( eyclohexlyethyl acrylate( PMA These values for the samemethacrylate )temperaturepolymers changed from 0. 6 kcal/ mol to 2.5kcal/mol and from 2.5 kcal/mol to 4.1 kcal/molSlope Intercept Calculated Calculatedfrom sloin n-hydrocarbons, according to these results theprobes with small Ah values were suitable forsolvent-polymer systems and those with larg0.00950.01704,180.00830.01153.743.22AHi values were suitable for nonsolvent-polymernis were in compliance with the valThe solubility parameter(8,) of a polymer can ues中国煤化工The solubility parame-be determined by Equation( 14)[ 18].8, was de-tersCNMHG and intercepts of thetermined from either slope or intercept ofplots were in good agreement with each other.straight line obtained by plotting the left-hand- Comparing the 8, values of poly( cyclohexyl methside of Equation( 14)versus 8, Fig 3 ).8, of poly acrylate )at different temperatures, it showedcyclohexyl methacrylate) was found as 5.17, that the solubility parameters decreased with第32卷0.080.080.0123x0.0318,c-0.90.04y-00107x0.0223,7-0.9574rdlc0.t0.08e04y-0.095x0172-0.95400.01003015,209462Fig3 Variation of the term[ 8/(RT )-xm/V, with 8, at the column temperatures of( a )423 K( b)433 K, (c)443 K and( d )453 K for poly( cyclohexyl methacrylateincreasing temperaturenique University, 2005[3 Shyamala M, Pragati Ranjan S, Sharma J V CInternationaConclusionsJournal of pharma Sciences, 20134] Guillet J E, Purnel J H. New Developments in Gas Chroma-Inverse gas chromatography technique was suctography: 322 Progress in Gas Chromatography. New YorkUSA: Wiley-Interscience, 1973: 323, 187[5 Smidsrod O, Guillet J E Macromolecules, 1969, 2(3 ):272temperature of poly( cyclohexyl methacrylate[6] Braun J M, Guillet J E Macromolecules,1977,10(1):101Some thermodynamic properties were obtained[7] DiPaola-Baranyi G, Guillet J E. Macromolecules,1978,11for poly( cyclohexyl methacrylate )-solute systems [8 Galin M. Maslinco L. Macromolecules. 1985. 18( 11):2192molar heat of [9] Kaya I, Ozdemir E Polymer, 1999, 40(9):2405sorption, partial molar free energy of sorption[10 Kaya I[ PhD Dissertation]. Elazig, Turkey: Firat Universi-ty,199partial molar heat of mixing at infinite dilution[11 Kaya I, Demirelli K. Polymer, 2000, 41(8):2855partial molar free energy of mixing at infinite dilu- 12] Papadopoulou S K, Panayiotou C J Chromatogr A,2012tion, Flory-Huggins interaction parameter and1229:23013] Reid C R, Prausnitz J M, Sherwood T K. The Properties ofweight fraction activity coefficient values. TheGases and liquids. 2nd ed. New York, USA: Mc Graw-Hisolubility parameter of the polymer was deter-mined with inverse gas chromatography tech-[14 Kaya I, Ozdemir E, Coskun M. J Macromol Sci A,1996le. The results obtained are in good agreement 15 Guillet JE, Purmel J H. Advances in Analytical Chemistrywith those of polymer-solvents and polymer-nonand Instrumentation Gas Chromatography. New Yorksolvents systems. The techniqurelatively un-USA: John Wiley Sons, 1973tion].Canakkale, Turkeycomplicated and the data reduction is carried out中国煤化工siy,201by a computerCNMHOmol Chem Phys, 1980, 181References[18 Kaya I, Ilter Z, Senol D. Polymer, 2002, 4.3(24):6455[19 Emam M N, Ahmed E E. 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