TEMPERATURE DEPENDENCE OF VISCOSITY IN THE SYSTEM OF BITUMEN - LOW MOLECULAR WEIGHT POLYETHYLENE

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1 Journal of Mehanial and Prodution Engineering (JMPE) ISSN (P): ISSN (E): Vol. 6, Issue 2, De 2016, 1-6 TJPRC Pvt. Ltd. TEMPERATURE DEPENDENCE OF VISCOSITY IN THE SYSTEM OF BITUMEN - LOW MOLECULAR WEIGHT POLYETHYLENE ABSTRACT SAYDAKHMEDOV ELYORBEK EGAMBERDI UGLI Head of Oil Proessing, Petrohemistry and Alternative Fuels Department JSC«O ZLITINEFTGAZ», Tashkent, Uzbekistan It is presented the results of studies on temperature effet on the rheologial properties of bitumen and bitumen-polymer mixture. The data show that the temperature has a signifiant effet on the hange in the rheologial properties of bitumen samples studied. KEYWORDS: Rheologial Properties, Petroleumbitumen-Polymer Mixture, Ativation Energy of Visous Flow Reeived: Ot 16, 2016; Aepted: Nov 15, 2016; Published: Nov 19, 2016; Paper Id.: JMPEDEC20161 INTRODUCTION The studies have been onduted on temperature effet on the rheologial properties of bitumen and bitumen-polymer mixture. The dependenes of low moleular weight polyethylene additives influene on transformation of rheologial properties of bitumen grade BND 40/60 and bitumen-polymer mixture were defined. Aording to the experimental data obtained with the appliation of rheologial model, there were hosen ratios and defined an analytial expression whih establishes temperature dependene of a shear stress and apparent visosity. It has been established that with the inrease in low moleular weight polymer in the bitumen, the temperature of its transition from the state of non-newtonian liquids into Newtonian inreases. Original Artile It has been defined, that the additive into bitumen 40/60 BND of low moleular weight polyethylene in a onentration of up to 5% leads to inrease in its apparent visosity more than 10 times and redues the energy of flow ativation. When arrying out the series of proessing steps, petroleum bitumen reahes the state of low visosity whih an signifiantly affet the effiieny of suh proesses. In this regard, the study of speifiity of bitumen s rheologial behavior and the temperature effet on hanging its rheologial properties is of undoubted interest. Researhes in the rheologial harateristis of bitumen are also needed for better understanding and preditinga mehanial behavior of bitumen in different thermal and mehanial impats. In [1, 2] In the studies there are generalizations of information on physiohemial, rheologial and other properties of bitumen. The authors [3] have formulated perspetive diretions of bitumen modifiation with pyro bitumen and oligomer additives, as well as there have been refleted peuliarities of bitumen s omposition and struture and given reasoning for rationale seletion of rheologial model of bitumen using plastiity parameter. In [4] the researh the visoelasti properties of bitumen whih was modified with rubber ompared to initial bitumen was studied. A strong additive effet of rumb rubber on the modulus of elastiity (inreases) whereas the

2 2 Saydakhmedov Elyorbek Egamberdi Ugli effet on phase angle (dereases). There is an available data on the relationship between rheologial properties of bitumen binder used for road oating and raks formation in the oating, in [5] there are given testing methods for rheologial properties of bitumen as well as numerous researh data on geophysial as phalts and polymer modified additives. An effet of polymer additives on the rheologial and other harateristis of bitumen is onsidered in [6], where given the values of ativation energy for visous flow of bitumen modifiations and several different onentrations of polymer modifiers. There has been observed a positive effet of some additives on the rheologial behavior of asphalt at low temperatures. Methods and Instruments Thus, bitumen is a highly visous material having the properties to hangerheologial feature sunder various fators, besides that, the visosity of bitumen onsiderably depends on its origin and its hemial omposition and struture. This paper presents the results of studies on the rheologial harateristis of bitumen of grade BND 40/60 GOST Fergana refinery, obtained from domesti oil. Basi physial and mehanial properties of the investigated sample of bitumen meet the requirements of GOST Basi physial and mehanial properties of road bitumen BND 40/60 in omparison with the requirements of GOST The rheologial properties of studied bitumen sample and its modified omposition with a low moleular weight polyethylene are studied on the instrument «Reostress» RS 600 ompany «Haake» (Germany). The blok diagram of the automated measuring omplex is shown in Figure 1. Figure 1: Blok Diagram of Automated Measuring Complex: 1-Head-Turning Rheometer 2-Cylinder, whih Interats with Bitumen, 3-Thermostate Jaket, where Water Cirulates with Constant Temperature, 4-Thermostate with a Digital Control System, 5-Head of Rheometer with Pneumati Rotation System, 6- Compressor, 7- Table with Pneumatimehanism of Vertial Motion for Adjustment, 8-Computer with Software to Control RHEOWIN Measurement And for Data Proessing The dependene of a shear stress on the rate at 150 C and the temperature at a shear rate of 120 s -1 for investigated sample of bitumen is shown in Figure 2 (urves (a) and (b) respetively). From the urves in Figure 2 it an be onluded that for studied sample of bitumen at melting temperature of 150 C the power rheologial modelis proved. K( T, ) n( T ) (1)

3 Temperature Dependene of Visosity in the System of Bitumen-Low Moleular Weight Polyethylene 3 Whereτ- shear stress, Pa s; T - temperature, C; γ - shear rate s -1, the temperature dependene of the shear stress (and apparent visosity) of the sample is desribed by the Arrhenius model: Aexp( E a / RT ) (2) where, Θ = 1 / (273 + T), A - onstant, E a - ativation energy, kj/mol, R - gas onstant, T- temperature C. The ativation energy of visous flow in the bitumen as in other non-ideal liquids is equal to moving the strutural units and onneted with energy of intermoleular interation. The values of the ativation energy of visous flow and natural logarithm of pre-exponential fator in equation (2) were determined graphially from semi-logarithmi form ln (τ) - 1/T of the equation (2). (a) Figure 2: Dependene of the shear Stress on Frequeny (a) and Temperature (b) for Bitumen Sample 40/60 Bitumen BND at a Shear Rate of The dependenies of visosity logarithm on reiproal value of absolute temperature are presented by the lines whih are very lose to straight ones. On the tangent ofinlination angle there was determined an average value of molar ativation energy of visous flow. In our work, the data proessing was performed by the method of least squares. Proessing our data whih were measured at 6 different temperatures there was obtained the value of ativation energy E a = 91kJ/ mol for bitumen. That is, the minimum energy neessary for the implementation of a visous flow proess. The quantitative parameters of power rheologial model and the maximum relative deviations in alulated and measured apparent visosities are respetively equal to: K = 0.37 Pa s -n, n = 0,98 and maximum error of 1.5%. Figure 3 shows the measured values of an apparent visosity of bitumen, depending on shear rate at various temperatures. These data demonstrate aonsiderable dependene of rheologial properties of studied sample on the temperature. (b)

4 4 Saydakhmedov Elyorbek Egamberdi Ugli Figure 3: The Dependene of the Apparent Visosity of BND 40/60 Bitumen on Shear Rate Attemperatures: - 90 C; C; C; C Figure 4 shows the results of an experimental study inrheologial properties of bitumen after modifiation with3% additive of low moleular weight polyethylene from the wastes of Shurtan Gas Chemial Complex. The solid lines in Figures 1 (a) and 3 show the alulated values of shear stress depending on shear rate and temperature aording to the model (1), K( T ) K exp( E( Θ Θ ) / R), n( T) m0 (1 m1 ( T T )) 1 (3) where flow ativation energye, and the parameter m1 depend on what temperature range is given to temperature T: EL, E EH, при T приt T T m 1 m1 L, m1 H, при T T приt T (4) Figure 4: Flow Curves After Bitumen s Modifiation with Additive of Low Moleular Weight Polyethylene at Different Temperatures. - at 100 C, C, Δ- 120 C, C, C In equations (3) and (4) - T is a ertain harateristi temperature, near whih a sharp hange of E andm 1 ours. This model an in many ases approximate rheologial experimental data in a wide range of temperatures with satisfatory preision. The proessing of obtained data showed that signifiant agreement between the alulated and experimental data is observed at temperatures above 100 C.

5 Temperature Dependene of Visosity in the System of Bitumen-Low Moleular Weight Polyethylene 5 The data show that the temperature has a signifiant effet on the hange in the rheologial properties of bitumen samples studied. An additive in the road bitumen BND 40/60 NMPE polymer in onentrations up to 5% inreases its apparent visosity more than 3 times. The energy of flow ativation is dereasing by 9.7%. The flow ativation energy dereases with the inrease in the flexibility of maromoleules, but the temperature dependene of visosity is treated less harshly. CONCLUSIONS The high values of ativation energy in the flow mode with progressive destrution proess of strutural links (transition area) due to the fat that in addition to the energy required for kineti energy transition to a new loation it is neessary to spend more energy on destrution of links between strutural elements of the system. Flow urves of bitumen samples in the temperature range of C are well desribed by a power-law rheology model. The exponent of the model inreases with inreasing temperature and at temperatures over 150 C the bitumen presents a Newtonian fluid. With inreasing ontent of a polymer in bitumen the temperature of its transition from the state of non-newtonian into a Newtonian fluid inreases, whih is of pratial interest. The investigated samples of bitumen at temperature of 70 C or higher do not show visous-plasti properties. Considered in the study approximation model suffiiently desribes the temperature dependene of apparent visosity of BND 40/60 bitumen modified by low moleular weight polyethylene in the onentration of up to 5% in a wide range of temperatures and shear rates. REFERENCES 1. Rudenskaya I. M., Rudensky A. V. Rheologial properties of bitumens. - M.: Vyssh. shool P Hoyberg A. D. Bituminous materials.asfalta, pithes, pithes P Rudensky A. V., Rudensky I. M. Struktura of bitumen, their rheologial properties and ways of modifiation. Rosdorniya's Works, Vol.6 4. Mahrez A., Karim M.R. Rheologial evaluation of again properties of rubber rumb modified bitumen, J. of the Eastern Asia Soiety for Transportation Studies Vol.5. P Isasson U., Lu X. Properties of bitumen s modified with elastomers and plastomers. Pro. 2 nd Eurasphalt & Eurobitume Congress Barelona Book II. P Hussein I.A., Iqbal M.H., Al-Abdul Whhab H.I. Influene of Mw of LDPE and Vinyl Aetate Content of EVA on the Rheology of Polymer Modified Asphalt. RheologiaAta Vol.45. P

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