Microsoft Word - 24-32 24 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 The Energy of Break or Deformation in Some Semi- Crystalline Polymers Widad H. Jassim Dept. of Physics / College of Education For Pure Science (Ibn Al-Haitham) University of Baghdad Received in :26May 2014, Accepted in :29September 2014 Abstract The aim of the current study is the investigation of tensile behavior of the semi - crystalline polymers : polypropylene (PP ) , high density polyethylene(HDPE) and low density polyethylene (LDPE) . The energy to break or deformation was determined as a function of extension rates , ( PP) was break at extension rate (5) mm/min but (HDPE) break at higher extension rates (25) mm/min while( LDPE) not break even at very high extension rates but it is deformation or failure . Keywords : energy to break , extension rates, polypropylene (PP) ,high density polyethylene(HDPE) and low density polyethylene (LDPE). 25 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 Introduction The energy at break of polymers is required firstly to select a material which enables desired performance of the plastics component under conditions of its application . Furthermore , they are also essential in design work to dimension a part from a stress analysis or to predict the performance of a part under different extension – rates involved [1] . IF a material is subjected to stress , the polymeric material behaves as a linear elastic solid .The local maximum in load- extension curve is called the yield point , beyond this point the material stretches out considerably and a neck is formed , this region is called the plastic region . In some polymers , further extension leads to an a abrupt increase in stress( load /cross sectional area) which is named strain hardening , then the material is rupture , the( load – extension) or ( stress - strain) behavior of polymeric material depends on various parameters like microstructure and extension rate ( strain rate) [ 2 ]. The very Common thermoplastic materials used for drainage pipes are high density polyethylene (HDPE) , low - density polyethylene (LDPE) and polypropylene (PP) , these polymers characterized as a semi - crystalline polymers , made up of crystalline regions and a amorphous regions [ 3,4 ]. crystalline regions are those of highly ordered, where the amorphous is a random region High–density polyethylene ( HDPE) with density( 0.941- 0.965) gm/cm3is a thermoplastic material composed of carbon and hydrogen atoms joined together forming long main chain of molecules or mers ( C2H3R ) where the root R is H , the longer the main chain , the greater the number of atoms , and consequently , the greater the molecular weight[6] .The molecular weight and the amount of branching determine many of the mechanical properties of the end product . Other common polyethylene materials is low – density polyethylene ( LDPE) with density ( 0.91- 0. 925 g /cm3) which is more branched , strength and flexibility than HDPE [7] . another thermoplastic materials used for drainage pipes is polypropylene with chemical stature C2H3R mers , where the root ( R ) is ( CH3 ) and density (0.900) g /cm3 [4, 8 ] . The physical and mechanical properties of plastics are governed by the structure and composition [9] , the mechanical properties like stress - strain relationship of some polymers are studied by Einar Dahl in 1973 [10] . The tensile deformation properties of several semi - crystalline polymers were studied by R . Hiss by developed a video - control for the stretching device in 1996 [11] .In1999 R. Hiss et. al carried out experiments of stress on polyethylene [12] and another experiments of stress –strain were carried out on polypropylene in 2003 by Y.Men and G.Strobl[13] . In 2007 P.Nagy and L.M.Va ,studied the relationship between constant strain rate and stress relaxation behavior of polypropylene [14] , Abdullah A.Hussein etal studied the mechanical behaviour of ( LDPE) in 2011 [7] . In this investigation the entire stress - strain relationship of two grades of polyethylene and polypropylene was determined . Experimental ASTM D638 ( Standard Test Method ) for tensile properties of plastics , is used to shape the drain pipes made by ( PP , HDPE and LDPE ) , the specimens are usually shaped as a flat ( dog bone ) with dimensions of ( 65 x 13x 3) mm , using the testing 26 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 machine Fig .(1 ) ,we try different extension rates , until the rupture is occured , or the specimen is failure . Result and Discussions The energies to break or deformation have been determined by calculating the area under the curves of ( load – extension ) or ( load - stroke) as in figures ( 2 – 4 ) with extension rate (5) mm/min for ( PP , HDPE , LDPE ) respectively , these curves are a basis of classification of a polymers [9] . The microstructure of ( PP ) is different than ( PE ), so ( PP ) was broken with brittle fracture at extension rate ( 5) mm / min but ( HDPE ) was broken at ( 25) mm/min as shown in the figure ( 5 ) , while ( LDPE ) was not broken even at very high extensions rates but it was deformation because its high flexibility which is in agreement with Gensler et.al. [15] , the further extension leads to an a abrupt increase in load (strain hardening )as in figure (4). For ( HDPE ) and ( LDPE ) the energies to deformation are increased with the increase of the extension rates , as shown in figure ( 6 , 7 ) respectively , which agree with Peterlin [16] and Jonnan et. al.[17]. Figure ( 8 ) showed the influence of microstructure of polymers on the values of energies to break or deformation. Table ( 1 ) illustrates that ( LDPE ) has higher values of energies to deformation than the values of ( HDPE ) because it was more flexible , Soft and Toughness. Conclusion 1- The tensile ( load – extension ) curve is a basis for classify the polymer in term of there brittleness , softness and toughness . 2- (LDPE) has a soft and tough behavior because its structure ( branch chain )with largely amorphous regions . 3- (HDPE) and (LDPE) have the same chemical structure but HDPE has a higher degree of crystalline , resulting in improving the strength and stiffness . 4- PP has higher strength and stiffness then it has higher values of energy to break than HDPE at (5) mm /min . 5- The energies to deformation of (HDPE )or (LDPE) are increased with extension- rates References 1-Keresztes , R ; Kalacska ,G. and Zsidai , (2011) Machinnability of engineering polymers , sustainable construction and design , 106-114. 2- Hiss, R.; Hobeika , S. and Lynn,S. ,(1999) Stress –Strain behavior of polymeric material Macromolecules ,32:4390 3-Send ,S. and Pasa ,Y. (2005) Effect of testing parameters on mechanical properties of polypropylene copolymer , polymer testing 24 :613-619 . 4- Lin,Y.; Gary , R. and Anne Hilter, (2011) The drainage pipes ,polymer, 52: 1635-1644. 5-Peterlin,A.J. ( 1971) Molecular model of drawing polyethylene and polypropylene , Material science,6 :490. 6- Zhu ,L.;Chiu ,F.and Quirk ,R. ( 1999) Polymer hand book 4th edition chapter V. 7- Abdullah ,A .; Abdulwahab ,A. and Qusay ,A. (2011) Mechanical behaviour of low density polyethylene / Shrimp shells composite , Journal of Basrah Researches Sciences.37 (3A/15) :5-10. 8- Loos, J. ; Peter mann, J. and Waldoefner, A. ( 1997) , Colloid and polymer Science ,275: 1088. 27 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 9- Shackelford ,E. and Alexander, W. ( 2001) , Materials Science and Engineering Handbook , Boca Raton : CRC press LLC. 10- Einar Dahl ( 1973) Stress-Strain tests of polymer modified concrete,Engineering laboratory report , 390.3 11- Hiss , R. ( 1996) , PhD theis , University freibug, Albert –Ludwiges . 12- Hiss ,R. ; Hobeika , S. ; Lynn ,C. and Strobl , G. . ( 1999) Experiment for (PE) and ( PP) Macromolecules : 32- 4390. 13- Men , Y. and Strol , G. (2003) The Sterss-Strain dependencies ,J.Macromolecules ,36 : 1889. 14- Nagy,P.;Vas ,L.M. (2007) Relationship between constant Strain rate and Stress relaxation of polypropylene ,express polymer letters ,1(2) :84-91. 15- Gensler ,R. ; Plummer ,C. and Kausch , H..( 2000) Influence of the loading rate on the fracture polypropylene , Polymer 41(10): 3809- 3819. 16 - Peterlin ,A. (1971) Energy of deformation of some polymers , J.Matter .Sci.6 (6) :490. 17- Jonan ,p. and Ferando Julin ( 2012) Tensile strength charactenstics of polypropylene composites reinforced with stone ground wood , Bio Resource 7( 3): 3188-3200. Table No. (1)The influence of extension rate on the energy to deformation of HDPE and LDPE Energy to deformation Kgf.mm )( Extension rate ( mm/ min ) LDPE HDPE 17545.6 5273.39 5 17936.1 5277.47 10 18723.4 5284.57 15 19066.3 2647.55 20 28 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 29 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 Figure No. (3)Load as function of stroke for HDPE with extension rate 5mm/min . Figure No. (4)Load as function of stroke for LDPE with extension rate 5mm/min Figure No.(5)Load as function of stroke for HDPE with extension rate 25mm/min 30 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 0 1000 2000 3000 4000 5000 6000 0 5 10 15 20 25 30 ) En er gy to b re ak (K gf .m m )mm(Extension rate Figure No. (6)Energy to deformation as a function of extension rate for HDPE Figure No. (7)Energy to deformation as a function of extension rate for LDPE 17400 17600 17800 18000 18200 18400 18600 18800 19000 19200 0 5 10 15 20 25 ) En eg y to b re ak ( Kg f.m m )mm(Extension rate 31 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 Figure No.(8)The influence of the kind of polymer on the energy to deformation 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 HDPE PP LDPEEn er gy to d ef or m at io n ( K gf .m m ) 32 | Physics 2015) عام 1(العدد 28المجلد مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة Ibn Al-Haitham J. for Pure & Appl. Sci. Vol. 28 (1) 2015 بلوریة –طاقة الكسر أو التلف لبعض البولیمرات شبھ وداد حمدي جاسم / جامعة بغداد )ابن الھیثم(قسم الفیزیاء / كلیة التربیة للعلوم الصرفة 2014ایلول 29 في:قبل 2014ایار 26:في استلم الخالصة بلوریة مثل -االستطالة ) للبولیمرات شبھ – ان الھدف من الدراسة الحالیة , ھو البحث في طبیعة العالقة ( القوة ) ،البولي أثیلین عالي الكثافة و البولي أثیلین واطى الكثافة.ppالبولي بروبلین( وأنجزت فحوصات الشد لقیاس طاقة الكسر أو فشل األنموذج دالة لمعدل السحب ،ینكسر البولي بروبلین بمعدل ) ، بینما ال mm/min(25) ولكن البولي أثیلین عالي الكثافة ینكسر عند معدالت عالیة جدا للسحب mm/min(5سحب ت العالیة جدا للسحب ولكنھ یتلف .ینكسر البولي أثیلین واطى الكثافة حتى عند المعدال ) HDPE) , بولي أثیلین عالي الكثافة ( PPطاقة الكسر , معدالت الشد , بولي بروبلین (الكلمات المفتاحیة : ) . LDPEوالبولي أثیلین واطى الكثافة (