The effect of sunlight on medium density polyethylene Water pipes

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International Conference on Technologies and Materials for Renewable Energy, Environment and Sustainability, TMREES17, 21-24 April 2017, Beirut Lebanon Thesunlight 15th International Symposium on District Heating and Cooling The effect of on medium density polyethylene Water pipes

Kareem A.the Jassim , Widad of Hamdi Jassim H. Mahdi Assessing feasibility using the, and heatShatha demand-outdoor Education of science-Ibn Baghdad .. Education college college of pure pure science-Ibn AlAl- Haithem, Haithem, Baghdad university, university, Iraq temperature function for a long-term district heatIraq demand forecast a* a*

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Abstract Abstract

I. Andrića,b,c*, A. Pinaa, P. Ferrãoa, J. Fournierb., B. Lacarrièrec, O. Le Correc

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IN+ Center for Innovation,density Technology and Policy (MDPE) Research - Instituto Superior Técnico, Av. Roviscostored Pais 1, 1049-001 was Lisbon, Portugal The The suitability suitability of of medium mediumb density polyethylene polyethylene (MDPE) water water pipes pipes beyond beyond (2 (2 years) years) being being stored outdoors outdoors was studied. studied. The The Veolia Recherche &radiation Innovation, 291evaluated Avenue Dreyfous Daniel, 78520 Limay, France strength at break. MDPE resistance of MDPE pipes to ultraviolet (UV) was by measuring changes in tensile resistance of MDPE pipes to ultraviolet (UV) radiation was evaluated by measuring changes in tensile strength at break. MDPE c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France pipes pipes under under study study have have two two formulations: formulations: the the first first without without carbon carbon black black (virgin) (virgin) and and the the anther anther with with carbon carbon black, black, the the samples samples were were exposed exposed to to UV UV radiation radiation using using an an accelerated accelerated weatherometer weatherometer for for (200 (200 h) h) to to simulate simulate the the effect effect of of (2 (2 years) years) of of exposure exposure to to 2 sunlight. than virgin virgin sunlight. The The values values of of tensile tensile strength strength at at break break of of MDPE MDPE with with C.B C.B have have higher higher values values (160.7Kg/cm (160.7Kg/cm2 )) than 22) after exposure MDPE with C.B cutoff at 25% of strain with tensile strength about (161Kg/cm22) before MDPE(137Kg/cm MDPE(137Kg/cm ) after exposure MDPE with C.B cutoff at 25% of strain with tensile strength about (161Kg/cm ) before Abstract exposure to UV radiation, exposure to UV radiation, but but it it is is cut cut off off at at 50% 50% of of strain strain with with the the same same value value of of tensile tensile strength strength after after exposure. exposure. The The percentage percentage of carbon black the degree of its dispersion have been determined by employing thermogravimetry (TGA) ofDistrict carbonheating black and and the degree of its dispersion have been determined by employing thermogravimetry (TGA) technique and networks are commonly addressed in the literature as one of the most effective solutions for technique decreasingand the reflected light microscopy reflected lightgas microscopy respectively greenhouse emissionsrespectively from the building sector. These systems require high investments which are returned through the heat © 2017 The Authors. Published by Elsevier Ltd. © 2017 The Authors. Published by Elsevier Elsevier Ltd. and building renovation policies, heat demand in the future could decrease, to the changed climate conditions ©sales. 2017 Due The Authors. Published by Ltd. Peer-review under responsibility of the Euro-Mediterranean Institute for Sustainable Development (EUMISD). Peer-review responsibility the prolonging under the investment returnof Peer-review under responsibility ofperiod. the Euro-Mediterranean Euro-Mediterranean Institute Institute for for Sustainable Sustainable Development Development (EUMISD). (EUMISD). The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand Keywords: pipe; strength; degradation Keywords: MDPE pipe; tensile tensile strength; TGA TGA degradation forecast. MDPE The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were * * Corresponding Corresponding author. author. Tel.; Tel.; compared with results from a dynamic heat demand model, previously developed and validated by the authors. E-mail address: address: [email protected] [email protected] E-mail The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the 1. Introduction 1.decrease Introduction in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the Plastic are by radiation and mechanical [1, 2]. brittleness, cracking Plastic pipes are affected affected by ultraviolet ultraviolet radiation and to mechanical stress [1, parameters 2]. The The results results brittleness, cracking and and coupledpipes scenarios). The values suggested could be used modify thestress function for the scenarios considered, and fading [3]. Ultraviolet (UV) radiation is a big problem for pipes exposed to sunlight; UV radiation has fading [3]. radiation is a big problem for pipes exposed to sunlight; UV radiation has (100 (100 –– 400 400 improve theUltraviolet accuracy of (UV) heat demand estimations.

nm). nm). The The ozone ozone layer layer absorption absorption the the extreme extreme UV UV (100 (100 –– 200 200 nm) nm) and and far far UV UV (200 (200 –– 280 280 nm), nm), only only UV UV ray ray with with length close (400 the © 2017wave The Authors. Elsevierto length wave close to to Published (400 nm) nm)byreaches reaches toLtd. the ground ground [4]. [4]. UV UV sunlight sunlight causes causes the the photo photo degradation degradation of of polymer polymer due due to chain chemical and results morphology and the mechanical properties underor responsibility of the Scientific The 15thin Symposium Heating and toPeer-review chain scission scission or chemical crosslinking crosslinking andCommittee results in inofchanges changes inInternational morphology and then then on theDistrict mechanical properties of polymer, ofCooling. polymer, the the tensile tensile strength strength used used to to monitor monitor degradation degradation process process [5]. [5]. Outdoor Outdoor testing testing takes takes years years of of exposure exposure to to

Keywords: Heat demand; Forecast; Climate change 1876-6102 © 1876-6102 © 2017 2017 The The Authors. Authors. Published Published by by Elsevier Elsevier Ltd. Ltd. Peer-review Peer-review under under responsibility responsibility of of the the Euro-Mediterranean Euro-Mediterranean Institute Institute for for Sustainable Sustainable Development Development (EUMISD). (EUMISD). 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Euro-Mediterranean Institute for Sustainable Development (EUMISD). 10.1016/j.egypro.2017.07.091

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the sun, so accelerated testing in Xenon– arc must be used to take much less time. Many studies have investigated of photo degradation of polymers. (Thomas et al., 2004) found that the flexural modulus for high density polyethylene (HDPE) increased 70% during the first (2000 h) of UV radiation and the craze began to appear [6]. (N. A. Saad et al., 2012) found that modulus of elasticity of polyvinyl chloride was decreased during the first (168 h) of UV exposure, which makes a change in its morphology [7]. Carbon black (C.B) acts as UV radiation screen for protection the PE form damaging against UV radiation. The resistance to UV by using C.B depends on its concentration and a degree of dispersion in polyethylene water pipes. Thermogravimetric analysis (TGA) is a technique for studying the kinetics of thermal degradation by reducing in weight with time [8, 9] and provides information on the determination of the mount of C.B [10, 11]. The objective of this work was to determine the tensile strength at break and use this parameter as an indicator of how the UV radiation affects the performance of virgin MDPE and MDPE with C.B water pipes for two years of exposure to sunlight in Iraq and to understand the role of C.B on production to UV radiation, the thermal degradation of water pipe was performed by (TGA) technique and Carbon black concentration in pipe was determined. Finally the relationship between the change in tensile strength at break of pipes and its morphology has been interpreted. 2. Materials and methods Virgin (MDPE) and MDPE with C.B were used in this study. The specimens for tensile test were cut from Iraqi water pipes in accordance with the standard method (ASTM–D638). The test was carried out on specimens with a crossed speed (5 mm/min) prior and post UV exposure for (200h) .The samples for tensile test are exposed to UV radiation using Xenon– arc at (2.3 W/m2) and wavelength of (300–350 nm) . Thermogravimetry analysis (TGA) was used to study the thermal degradation of MDPE pipes. The samples of about (50 mg) were set in the constipated and heated with heating rate (10 oC /min) to estimate the percentage of (C.B) at higher degree of heating. The crazes formation in pulling samples and the C.B distribution can determine using optical microscope with magnification (200 X). 3. Results and discussion Figure.1represents the effect of UV radiation in virgin MDPE, the tensile strength at yield is about (205Kg/cm2) at strain (5%) for the virgin MDPE before and after exposure to UV radiation, that means UV radiation does not effect on stress value of virgin MDPE at lower values of strain (1.25,5and10%)but when the strain values are increase (15, 20, 25 and 30%) the virgin MDPE will not bear higher values of stress after exposure to UV radiation, because of the damage effect by UV radiation on virgin MDPE as shown in figure(2) after that the cross linking took place at higher values of stain (50%) where the strength at break is about (137Kg/cm2) for virgin MDPE after exposure to UV radiation and about (125 Kg/cm2) for virgin MDPE before exposure, this results are good agreement with [6] . The change in tensile strength is explained using the morphology of MDPE under stress prior and post UV exposure. The stress causes the crazes on virgin MDPE before exposure as in figure (2–a). The UV exposure causes defects, as shown in figure (2–b), where there was a light and dark area was found, that means the sample has roughness which effect on tensile strength.

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Fig. 1: Stress–strain curves of virgin PE pipes prior and post UV exposure

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Fig. 2: Optical microscope images of virgin MDPE a- prior UV exposure b- post UV exposure (Magnification 200 X)

Figure.3 shows that C.B play a very good role on the product of MDPE against UV radiation, were the MDPE with C.B pipes bears higher values of loading without cut off at strain (30, 40 and 50%) , the strength at yield at strain (1.25%) is about (214Kg/cm2) for MDPE with C.B after exposure to UV and (206 Kg/cm2) before exposure, while the strength at break about (161 Kg/cm2) at strain (50%) for MDPE with C.B after exposure to UV and have the same value for MDPE with C.B before exposure to UV but at a half value of strain (25%), that because C.B act as screen against UV.

Fig.3: Stress – strain of MDPE with C.B prior and post UV exposure

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Fig. 4: Optical microscope images of MDPE with C.B

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a - prior UV exposure b- Post UV exposure (magnification 200 X)

Carbon black has a good distribution and little amount of crazes produced by tensile test as shown in figure 4–a. C.B plays a good role in protecting against UV light exposure by reducing the damages, as shown in figure 4-b. Carbon black enhanced the tensile stress at break of MDPE before exposure to UV, as shown in Figure (5) where at strain (1.25%) MDPE with C.B have higher values of strength at yield (206.75Kg/cm2) than that of the virgin MDPE pipes (142.8Kg/cm2) at strain (25%) the MDPE with C.B have tensile strength at break (161.64 Kg/cm2) which is higher than that of virgin MDPE(125 Kg/cm2) at strain (50%)that because C.B work as reinforcement centre on MDPE but the virgin MDPE have higher ductility, so it bear high values load without cut off at strain(30,40and50%) .

Fig. 5: The effect of C. B on tensile strength at break before UV exposure

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Fig.6: The effect of C .B on tensile strength at break after UV exposure

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From figure.6 we can show that at strain (1.25%) the tensile strength at yield of MDPE with C.B about (214Kg/cm2) and about (156 Kg/cm2) for virgin MDPE and also the tensile strength at break of MDPE with C.B have higher value (160.7 Kg/cm2) than that of virgin MDPE (137 Kg/cm2) that means C.B particles enhanced the tensile strength at yield and break. Figure.7 shows the TGA curve of PE pipe from room temperature to 630 oC with heating rate (10 oC/min). The decomposition starts at 300 oC and, the weight loss to 40% at 470oC. The concentration of carbon black is found to be ranging from (2-3 %) at temperatures range (618–630o C). The degradation occurs due to exposure of PE pipe to oxygen and heat; these two factors will cause the free radical (RH) to constitute a hydroperoxide groups (ROOH). Under the effect of UV or heat the (ROOH) will form the alkoxy radical (RO.) and hydroxyl radical (OH), the (RO.) will decompose to some carbon compounds [5]

Fig.7. TGA curve of MDPE with 2% C.B at heating rate (10 ͦ C/min)

Conclusions Tensile strength at break is a good indicator of the response of plastic pipes when exposure to sunlight. For virgin MDPE pipes the exposure to UV radiation will enhance its tensile strength at break, and cause the defect in its morphology. C.B product the MDPE pipes against UV radiation and the pipes will not cut off until (50%) of strain. C.B acts also as mechanical reinforcement centres and enhanced the strength at break of MDPE before exposure to UV radiation. Finally TGA is a very good technique to estimate the Carbon black concentration in MDPE pipes and also determination the thermal stability of these pipes Acknowledgments The authors would like to thank the University of Technology, Baghdad, Iraq for providing support for their technical support to conduct this research. References [1] S.Bal, D.Mahesh,T.K.Sen etal., Journal of minerals and Materials characterization and Engineering.2007., 6. [2] A. Ollick and A.M.AL-Amri, Alexndria Engineering Journal. 2000.. 39. [3] T. Corrales, F. Catalina, etal. : Journal of photochemistry and photobiology A: Chemistry.2000. 147, 213- 224. [4] Pieter, J. Aucamp etal ., Photochem .Photobiol .Sci, ( 2004 ), 3, 1-5 . [5] Maryudi, Anwaruddin Hisyam etal. International Journal of Engineering research and applications.2013. 3, 1156–1165 [6] Thomas Lundin , Steven M. Cramer etal ., Journal Of Materials In Civil Engineering .2004 . 547 – 551 . [7] N.A.Saad, M.H.Maamory etal., Materials Sciences and applications. 2012. 3,784-792 . [8] Subramanian Ravichandran, International Journal of Chem Tech Research .2016. 9, (1) 308. [9] W.V.Vicki , Tunku Atiqah , International Research Journal of Engineering and Techology. 2016 .3 .

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[10] B .W-Lodi, EJGE. 2012,, 17, 3339 -3349. [11] Kai Yi, Dongbing Geng etal. 10 th International Conference on Composite Science and Technology. 2015.

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