Copolymer of Decyl acrylate and Styrene: Synthesis, Characterization and Viscometric Studies in Different Base stocks

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1 Avilble online t Advnces in Applied Science Reserch, 2011, 2 (2): ISSN: CODEN (USA): AASRFC Copolymer of Decyl crylte nd Styrene: Synthesis, Chrcteriztion nd Viscometric Studies in Different Bse stocks Prnb Ghosh * nd Tpn Ds Nturl Product nd Polymer Chemistry Lbortory, Deprtment of Chemistry, University of North Bengl, Drjeeling, Indi ABSTRACT In continution of our studies towrds the development of polymeric dditives for lubricting oil we report herein the synthesis, chrcteriztion nd viscometric studies of homo polymer of decyl crylte nd its copolymer with styrene in different bse stocks t 40 0 C. In order to get more informtion bout the structure nd morphology of the polymer when dissolved in bse stocks (i.e. in field ppliction), viscometric mesurements of the synthesized homo polymer s well s tht of the co polymer were performed in the bse oils t 40 0 C. Different equtions were used to clculte intrinsic viscosity nd viscometric constnts vlues nd moleculr weight of the synthesized polymers. Keywords: Homopolymer, copolymer, viscometric mesurements, pour point depressnt, lubricting oil. INTRODUCTION Bse oil lso known s lubricnt bse oil, is the bsic building block of lubricnt. They re complex mixture of prffinic, romtic nd npthenic hydrocrbons with moleculr weights rnging from medium to high vlues, very low voltility nd with high viscosity index. The proportions of different hydrocrbon components determine the chrcteristics of the bse oils. The performnce of lubricnt bse oils is often governed by their rheologicl properties such s low temperture fluidity, viscosity nd viscosity temperture reltionship. For exmple, to provide n effective performnce t low tempertures s well s t high tempertures, n engine lubricnt should hve good low temperture fluidity nd miniml vritions of its viscosity with temperture. 272

2 Properties of such bse oils cn be improved by the incorportion of suitble performnce polymer, generlly clled dditives. They dded to bse oils to imprt specific property to the oil. Some of them imprt new nd useful properties to the lubricnt, nd others enhnce properties lredy present. These dditives re more ctive thn the bse oils. However, some of their properties re very often controlled by the chemicl compositions of the bse oils wheres some properties re controlled by the structure of the chemicl dditives designed for tht purpose. Acrylte bsed polymers nd copolymers used in lubricnt compositions for improving the viscometric nd rheologicl properties of the lubricnt [1,2]. They lso looked upon to provide dditionl performnce chrcteristics such s improved low temperture fluidity nd disprsncy. However, owing to less therml stbility, they redily undergo depolymeriztion with constnt decrese of the oil viscosity compounded with these polymers. Therefore, the recent reserch on crylte bsed dditives hs been concerned on copolymeriztion of it with stbilizing monomers. Since it is well known tht inclusion of styrene in the composition of n dditive increses the therml stbility of the copolymer, copolymeriztion of decyl crylte with two different mss concentrtion of styrene hs been crried out which my be very useful performnce dditive such s pour point depressnt or viscosity modifier for petroleum nd synthetic oil. Recent reserch [3] towrds the understnding of dditives performnce in bse oils indicted tht the performnce of dditives when used in lubricting oil nd pplied in field conditions re very much dependent on the structure nd morphology of the polymer dissolved in it. Therefore, viscometric studies (tht cn be crried out in ny lbortory owing to the simplicity of equipment required), with these dditives in bse oils my give vluble informtion s fr s the bse stock employed nd morphologicl feture of the polymer in dilute solution in the bse oils is concerned[4]. Therefore, the study my be very useful for predicting the performnce of the dditive in bse oils of different compositions. The commonly used equtions employed to determine the viscometric prmeters of the polymer re [4-7] Mrk Houwink Sukurd: [η] = KM (1) Where [η] is the intrinsic viscosity, M is the moleculr weight, the vlues of prmeter K nd depends on the type of polymer, solvent, nd temperture. Huggins η sp / C = [η] h + k h [η] 2 h C (2) Kremer ln η r /C = [η] k - k k [η] 2 k C (3) Mrtin ln (η sp /C) = ln[η] m + k m [η] m C (4) Schulz-Blschke η sp /C=[η] sb +k sb [η] sb η sp (5) Where, η r = t/t 0, ( t 0 is the time flow of pure solvent nd t is time flow of polymer solution) reltive viscosity or viscosity rtio ; η sp = η r -1 specific viscosity 273

3 [η] h = intrinsic viscosity, respective to Huggins eqution. [η] k = intrinsic viscosity, respective to Kremer eqution ; [η] m = intrinsic viscosity, respective to Mrtin eqution, [η] sb = intrinsic viscosity or limiting number, respective to Schulz Blschke eqution; k h, k k, k m nd k sb Huggins, Kremer, Mrtin nd Schulz- Blschke coefficients, respectively, C is the concentrtion in g/cc. Aprt from the bove, some reltions hve lso been proposed for determining the intrinsic viscosity in dilute polymer solution from single point determintion. These methods hve the dvntge of being considerbly fster nd cn be dequte when lrge number of smples must be nlysed in short period of time, prticulrly in industril lbortories. Most useful of them [4-8] re Solomon- Ciute (SC, Eq. 6) nd Deb Chtterjee (DC, Eq. 7) reltions [η] = [2(η sp - lnη r )] 1/2 /C (6) [η] = (3lnη r + 3/2η sp 2 3η sp ) 1/3 / C (7) The use of these equtions hs been derived under the supposition of the vlidity of the reltionship [4] k h + k k = 0.5 Scheme I Esterifiction: H 2 C CH COOH + C 10 H 21 OH Conc. H 2 SO 4 Toluene, HQ inhibitor Den Strk Apprtus H 2 C CH COOC 10 H 21 + H 2 O Scheme-II Homopolymeristion: COOC 10 H 21 n H 2 C CH COOC 10 H 21 Scheme-III Copolymeristion: Toluene, BZP 80 o C, 6hr. CH 2 CH n x H 2 C CH COOC 10 H 21 COOC 10 H 21 + CH CH 2 Toluene, BZP 80 o C, 6hr. H C CH 2 x CH 2 CH y y 274

4 MATERIALS AND METHODS Esterifiction of decylcrylte (DA) from crylic cid nd decyl lcohol. Decyl crylte ws prepred by recting crylic cid with decyl lcohol (1.1:1 molr rtio). The rection ws crried out in resin kettle in the presence of concentrted sulphuric cid s ctlyst, 0.25% hydroquinone s polymeriztion inhibitor for crylic cid, nd toluene s solvent under slow strem of deoxygented nitrogen. The rectnts, which were mixed with toluene, were heted grdully from room temperture to C using well-controlled thermostt. The extent of rection ws followed by monitoring the mount of liberted wter to give the ester, decyl crylte. Purifiction of prepred ester The prepred ester ws purified ccording to the following procedure: suitble mount of chrcol ws dded to the ester, llowed to reflux for 3 h, nd then filtered off. The filtrte ws wshed with 0.5N sodium hydroxide in seprting funnel nd then shken well. The entire process ws repeted severl times to ensure complete removl of unrected cid. The purified ester ws then wshed severl times with distil wter to remove ny trces of sodium hydroxide; the ester ws then left over night on clcium chloride nd ws then removed by distilltion under reduced pressure nd ws used in the polymeriztion process. Preprtion of homo polymer of DA nd its copolymer with styrene nd their purifiction The polymeriztion ws crried out in four necked round bottom flsk equipped with stirrer, condenser, thermometer, n inlet for the introduction of nitrogen nd dropping funnel through which to dd styrene drop wise. In the flsk ws plced desired mss of DA nd inititor (BZP) followed by the desired mss of styrene ws dded drop wise for 2 h in the presence of toluene s solvent. The rection temperture ws mintined t 353 K for 6 h. At the end of the rection time, the rection mixture ws poured into methnol with stirring to terminte the polymeriztion nd precipitte the polymer. The polymer ws further purified by repeted precipittion of its hexne solution by methnol followed by drying under vcuum t 313K. A homo polymer of DA ws similrly prepred nd purified under the sme conditions for use in reference experiments. Preprtion of Polymer bse oil blend Bse oils of two different viscosity grdes, BO1 nd BO2 (Tble 1) were collected from two different refineries, A nd B. In ll the cses blending of the dditives with the oils were crried out by tking required mount of polymer in the clculted mount of oil (w/w) nd then heting the mixture t 60 0 C for 30 min with constnt stirring. MEASUREMENTS Spectroscopic mesurements IR spectr were recorded on Shimudzu FT-IR 8300 spectrometer using 0.1mm KBr cells nd the spectr were recorded t room temperture within the wve number rnge (400 to 4000) cm -1. NMR spectr were recorded in Brucker Avnce 300MHz FT-NMR spectrometer using 5 mm BBO probe. CDCl 3 ws used s solvent nd TMS s reference mteril. 275

5 Viscometric mesurements Viscometric properties were determined t 313 K in different bse stocks, using n Ubbelohde OB viscometer. Experimentl determintion ws crried out by counting time flow t lest five different concentrtion of the smple solutions. The time flow of the solution ws mnully determined by using chronometer. In single mesurement the lowest vlue of solution concentrtion ws chosen for the clcultion. The viscometer ws clibrted frequently with distilled wter. The viscosity results were checked ginst viscosity of known solutions nd uncertinty ws found to be nerly 0.17 %. Precutions regrding prevention of evportion of solvent were tken in ll the cses. For the viscosity verge moleculr weight determintion, the constnts K = dl/ g nd = [3,9] were employed in Mrk Houwink Sukurd reltion Thermo grvimetric nlysis (TGA) The thermogrms in ir were obtined on mettler TA 3000 system, t heting rte of 10 K min -1. RESULTS AND DISCUSSION Spectroscopic nlysis FT-IR spectrum of the homo polymer (Figure 1) exhibited bsorption t 1732 cm -1 due to ester crbonyl stretching vibrtion. Pek t 1260 nd t 1175cm -1 cn be explined owing to the C-O (ester bond) stretching vibrtion nd the bsorption bnds t 975,750 nd 711 cm -1 were due to the bending of C-H bond. The brod pek rnging from cm -1 ws due to the presence of stretching vibrtion. The existence of the copolymer ws confirmed by FT-IR nd NMR nlysis. The copolymer in its IR spectrum (Figure 2) showed brod pek rnging from 1732 to 1720 cm -1. This ws ttributed to the stretching vibrtion of the ester crbonyl group nd to C-H bond of the phenyl group of styrene. In the 1 H NMR (Figure 3) spectr of one of the respective copolymers, brod multiplte centered t 8.07 ppm indicted the presence of phenyl group. A brod singlet centered t 4.06 ppm ws due to the proton of the OCH 2 group. The bsence of singlets between 5 nd 6 ppm indicted the bsence of vinylic protons in the copolymer. The proton decoupled 13 C NMR spectrum (Figure 4) of the bove smple of copolymer ws in complete greement with the originl structure-i COOC 10 H 21 H C CH 2 CH 2 x CH y Structure-I 276

6 The extent of incorportion of styrene in the polymer chin ws determined through comprison of re of OCH 2 group t 4.06 ppm in the re of signl due to phenyl protons t 8.07 ppm bsed on erlier reports [10] s well s on the bsis of our erlier pper [11]. It ws further verified through n nlysis of FT-IR spectrl dt [6]. The intensity of C=O bsorption in FT-IR spectr of present copolymers, s compred to the crbonyl bsorption in stndrd, were nlyzed for quntittive determintion of the content of crylte component in the copolymer. The comprtive results obtined on comprisons re presented in Tble-2. Physicl properties of bse oils re tbulted in Tble 1. Viscometric dt were obtined using the six eqution mentioned. A liner reltion for the plot of logη sp vs log c[η] obtined for ll smples [Figure 5 & 5b] indicted tht mesurements were performed in Newtonin flow[12,13]. Huggins (H), Kremer (K), Mrtin (M) nd Schulz Blscke (SB) equtions were pplied in grphic extrpoltion, providing the respective vlues of intrinsic viscosities nd constnts. In single point determintions, Schulz Blschke (SB), Solomon Ciut (SC) nd Deb Chnterjee (DC) equtions were employed. SC nd DC re independent of ny constnt vlue. In spite of being dependent on constnt, the Schulz Blschke (SB) eqution is commonly pplied in single point determintions becuse it ws found tht k sb = 0.28 for mny polymer-solvent systems [4-7,14]. In this work, this vlue ws used. Thermogrvimetric nlysis (TGA) in Tble 3 showed tht introduction of styrene rises the therml stbility of the copolymer in comprison to the homopolymer. Tble 4-5 presents intrinsic viscosity [η] vlues of polymer solution in bse oils BO1 nd BO2 relted to ll equtions for the smples nlysed. Considering the oils (BO1 nd BO2) nd compring the vlues of [η] for homo nd copolymers, it is noticed tht the higher vlues were obtined in BO2 oil compred to BO1 oil. Thus considering ll the polymers (homo nd copolymers), oil BO2 ppered to be more comptible to the polymer nd thus pointing towrds providing more extended conformtions of the polymers. This fct is further supported by the respective k h +k k vlues, which is well within 0.5 (Tble 7). Lower vlues in BO1 oil in comprison to the BO2 oil, indicting contrcted structures with str like conformtion for the dditive in this oil. Vrition of [η] obtined by grphic extrpoltion method (eqution 2-5) ws found to be less compred to those obtined by single point determintion method (eqution 6-7) without ny restriction to lubricting oil. It is lso observed tht [η] vlues decrese with the incorportion of styrene, but increses with increses in styrene concentrtion in cse of oil BO2 nd decreses in oil BO1. [η] vlues obtined by using DC eqution re lwys higher irrespective of the nture of the bse stock. It is lso observed tht there is drop in intrinsic viscosity vlues in cse of copolymer when dded to bse oils, prticulrly in BO1 oil, in comprison to the homopolymer. However, it does not chnge much with increse in styrene concentrtion in BO2 oil. Although the chnge is similr in BO1 oil, but the drop in intrinsic viscosity vlues of the copolymer is more thn wht ws observed in oil BO2 nd the reduction in intrinsic viscosity vlues grdully increses with the increse in styrene concentrtion. 277

7 Tble 6 & 7 presents vlues of viscometric constnts clculted for homo nd co polymers in BO1 nd BO2 oil respectively, k h nd k k fitted in the rnge of good solvents, wheres smple P-3 in BO1 oil indicting more incomptibility. Although k sb vlues found different from 0.28 in cse of BO1 oil, but it hs close tendency to cquire this vlue (except P-3) in cse of oil BO2. It is lso importnt to observe tht the reltion k h +k k =0.5 ws not found for the gret mjority of smples nlyzed. However, intrinsic viscosities obtined by using single point determintion methods were similr to vlues obtined by using grphic extrpoltion method with smll percentge differences. So vlues different from 0.5 did not put ny restriction for the ppliction of SC nd DC eqution. Tble 1. Bse oil properties Bse oil Density (g.cm - 1 )t 40 0 C Viscosity t 40 0 C Viscosity t C Cloud point Pour point BO BO Tble 2. Composition of the monomers in the co polymers in terms of mss frction determined by PMR nd FT-IR spectro photometric method. P-1 is homopolymer of decyl crylte (DA); P-2 to P-3 is the copolymer of DA+ different mss frctions of styrene Smple No % of weight in the feed % of weight in copolymer DA Styrene By PMR method By FT-IR P P P Tble 3. Therml Grvimetric Anlysis Dt of ll prepred smples Smple Decomp.Tempr PWL P-1 250/340 23/86 P-2 300/400 45/84 P-3 320/430 60/85 Tble 4. Intrinsic viscosity vlues of ll prepred smples in BO1 oil clculted by using different eqution (eq 2 to eq 7). - extrpoltion of grph, b- single point determintion method. Smple [η] h [η] k [η] m [η] SB [η] b SB [η] b SC [η] b DC P P P Tble 5. Intrinsic viscosity vlues of ll prepred smples in BO1 oil clculted by using different eqution (eq 2 to eq 7). - extrpoltion of grph, b- single point determintion method. Smple [η] h [η] k [η] m [η] SB [η] b SB [η] b SC [η] b DC P P P

8 Tble 6. Viscometric constnt vlues in BO1 oil Smple k h k k k m k sb k h +k k = 0.5 P x P P Tble 7. Viscometric constnt vlues in BO2 oil Smple k h k k k m k sb k h +k k = 0.5 P P x P Tble 8-9 presents the percentul differences of intrinsic viscosity vlues where Huggins vlue tken s references. In both the oils it is observed tht tht differences is smller in grphic extrpoltion method compred to single point determintion method. It is lso observed tht the differences is smller in oil BO2 compred to oil.bo1 Tble presents viscometric moleculr weight of ll the polymers (homo nd copolymer). Homopolymer showed higher moleculr weight thn the copolymer. As expected the moleculr weights re greter in oil BO2 compred to oil BO1. Agin in oil BO1, grdul decrese in viscometric moleculr weight of the copolymer ws observed with increse in styrene concentrtion lthough such vrition ws not observed in oil BO2. Tble 8. Percentul differences ( % = 100x [η]/[η] h 100) of intrinsic viscosity vlues (In BO1 oil), Where Huggins vlue tken s reference Smple K M SB SB b SC b DC b P P P Tble 9. Percentul differences ( % = 100x [η]/[η] h 100) of intrinsic viscosity vlues (In BO2 oil),where Huggins vlue tken s reference Smple K M SB SB b SC b DC b P P P Tble 10. Viscometric moleculr weight of ll prepred smple in BO1 oil by using Mrk Houwink eqution [η] = KM,Where K= nd = Smple Μ h M k M m Μ sb b Μ sb b Μ SC b Μ DC P P P

9 Tble 11. Viscometric moleculr weight of ll prepred smple in BO2 oil by using Mrk Houwink eqution [η] = KM,Where K= nd = Smple Μ h M k M m Μ sb b Μ sb b Μ SC b Μ DC P P P Figure 1. FT-IR spectrum of poly decylcrylte Figure 2. FT-IR spectrum of copolymer of decyl crylte with styrene 280

10 Figure 3. 1 H NMR spectrum of copolymer of decyl crylte with styrene Figure 4. 13C NMR spectrum of copolymer of decyl crylte with styrene 281

11 Figure 5. Plot of logη sp vs logc[η] for BO1. CONCLUSION Viscometric nlysis of the polymer my be crried out in lubricting oil to get more informtion bout their morphologicl structure when dded to the oil s performnce dditive. Oil comptibility of the dditive cn be predicted esily through Viscometric nlysis. Study lso indicted tht styrene incorportion enhnces the therml stbility of this crylte copolymer used s performnce dditive in lubricnt formultion. This work is probbly the first report of viscometric studies of polymeric dditives in bse oils. REFERENCES [1] R. M. Mortier, nd S.T. Qrszulik, Chemistry nd Technology of Lubricnts, second ed., Blckie Acdemic nd Profession: London [2] A. K. Chtterjee, P. S. N. Murthy, G. C. Joshi, Mcromolecules Current Trends. 1995, 1(3). [3] Ivn I. Mello, M. C. Delpech, F. M. B. Coutinho, F. F. M. Albino, J. Brz. Chem. Soc., 2006, 17 (1), [4] M. C. Delpech, F. M. B. Coutinho, M. E. S. Hbibe, Polym. Test. 2002, 21, 411. [5] C. K. Schoff, Concentrtion dependence of the viscosity of dilute polymer solutions: Huggins nd Schulz-Blschke constnts, Polymer Hndbook. John Wiley: New York [6] A. A. A., Abdel-Azim, A. M. M.S. Att, W. Y. Frht, Polymer, 1998, 39, 26. [7] H. U. Khn, V. K. Gupt, G. S. Bhrgv, Polym. Commun. 1983, 24, 191. [8] J. W. Qin, G. H. Zhou, W.Y. Yng, Euro. Polym. J. 2001, 37, [9] D. Srivstv, Irnin Polym. J (6),

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