IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.24 (1) 2011 An FTIR Study o f Characterization of Neat and UV Stabilized Nylo n 6,6 Polymer Films H. A. Mahdi Departme nt of Physics , College of Education I bn Al-Haitham, Unive rsity of Baghdad Recei ved in August 22 2010 Accepted in Nev. 9 2010 Abstract The work is concerned with the characterization of as cast films of neat and U V-st abilized ny lon 6,6 by emp loy ing FT IR measurements. Band assign ment is made for neat and UV- st abilized ny lon 6,6 using FT IR sp ectra confirm their molecular st ructure. UV-stabilizer added to ny lon 6,6 has caused reduction in the absorbance of the vibrational b ands and thus st abilizes the behavior of the poly mer in the end and uses sp ecially in harsh environment. Keywords: Ny lon 6,6, UV-st abilizer, FTIR sp ectra. Introduction Poly mer characterization is an essential st ep in working with p oly mers. The main characterization techniques involve the use of Fourier transform infrared and x-r ay diffraction methods. As a rule, such efforts are directed toward a sp ecific p urp ose. The st ructure and molecu lar conformation of the macromolecules ultimately determine the mechanical, p hysical and chemical p rop erties of p oly mers [1]. T hus p recise characterization of molecu lar ord er is a p rimary p rerequist to understandand macroscopic p rop erties of p oly meric materials [2,3]. Ny lon is a generic designation for a family of sy nthetic p olymers known as p olyamides (PA), and ny lon 6,6 is one of the most imp ortant engineering thermop last ics often used in adverse environ ment. The nature of the chemical repeat unit (p resented in figur e 1) p ose the p oly mer in many industrial app lications such as ny lon fibers for carp eting, clothing, tire cord and solid ny lon for bearings and gears due to its good abrasion resistance and self-lubricating p rop erties and ny lon ribbons for ty ing cables due to its good creep modulus [4]. The p oly mer is sy nthesized by condensation p olymerization of hexamethy lenediamine and adip ic acid. It is semi- cryst alline and the cryst als melt at high temp erature. In sp ite of its sup erior p rop erties, ny lon 6,6 is very sensitive to moist ure absorp tion and moist ure content must be controlled durin g melt p rocessing of ny lon 6,6 [5]. The aim of the present work is directed in the key p oints of characterization of p oly mers emp loying FT IR technique. Experime ntal Ribbons of ny lon 6,6 were obt ained from local market. T he ribbons were dissolved in a mixture of 1:1 weight ratio of formic acid and p henol at ambient temp erature. The mixture was cast into a glass mold and left to dry at ambient temp erature. The cast ny lon films were p eeled from the mold and the FT IR sp ectra have been record ed in the r ange 400-4000 cm -1 using shimadzu 8400 series at Ibn-Sina chemical indust rial center. The st andard samples were IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.24 (1) 2011 made by mixing finely chopped polymer with KBr and comp ressing the mixture in a p ellet- making p ress. T he KBr discs with p olymer were placed in the FT IR cell and the sp ectra were recorded. The FT IR sp ectrum is a useful tool to identify the chemical nature of the p olymer and to determine its comp osition. Results and Discussion FT IR sp ectroscopy has been applied in the identification of the basic st ructural units of ny lon 6,6 and UV stabilized ny lon 6,6. The FT IR sp ectra of the two t yp es of p oly mers are p resented in figures 2 and 3. Band p ositions in the sp ectra are utilized in confirming the molecu lar st ructure of the poly mer [6,7]. Absorbance was calculated as: Abs = log T = log (I/Io) where T is the transmittance and I/Io is the relative intensities of sample and st andard resp ectively. The vibrational frequencies of all the fundamental bands alon g with their relative intensities and p robable assignments are given in tables 1 and 2 for both the neat and UV st abilized nylon 6,6. Comparison of t he frequency bands of ny lon 6,6 with t he referen ce ny lon 6,6 [8] confirm that the cast neat films are those for ny lon 6,6 with band shifts not exceeding ± 5 cm -1 . This is characterized by the major band: the amide bands at 1639 and 1539 cm -1 and N-H, CH2 (a sy mmetric st retching) and CH2 (sy mmetric st retching) at 3306, 2932 and 2862 cm -1 resp ectively. These bands are indicative of their high absorbance (see table 1). For t he UV st abilized cast ny lon 6,6 films however, the amid e bands have shifted fro m those of the neat ny lon 6,6 sample by about 20 cm -1 due to the effect of UV st abilizer. It is also noted from the absorbance results in table 2 that the UV st abilized materials tend to reduce the absorbance of all the bands assign ed a consequence that characterization is useful in identify ing the chemical nature of the polymer. Conclusion The characterization st udy on neat and UV-stabilized ny lon 6,6 has been carr ied out using imp ortant exp erimental technique. Their molecular st ructures were confirmed by FTIR sp ectra from assignment of absorbance bands. Once the molecu lar st ructure is understood, it becomes easy for a p oly mer scientist to relate the p olymer structure to its p erformance p rop erties in end use. Re ferences 1.Sandler, S; Karo, W; Bonesteel, J and Pearce, E.M . (1998) ,Poly mer sy nthesis and characterization: A labor atory manual, Academic p ress, Finland. 2. Carraher, C. (2003), polymer chemist ry 6th ed. Dekker, New York. 3.Bicerano, J. (2002) ,Prediction of polymer p rop erties”, Dekker, New York. 4. M odern Plastic Ency clop edia Handbook, (1994) M cGraw hill, New York. 5. M elvin, I. Kohan, (1973) ,Ny lon plastics” John Wily and Sons, USA. IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.24 (1) 2011 6.Nakamoto, K. (1997) ,Infra red and Rawan sp ectra of inorganic and coordination comp ound, 5th ed., John Wiley and Sons, New York. 7. Charles, J.; Ramkumar, G.R.; Az hagiri, S. and Gunase Karan (2009) ,FTIR and thermal st udies on ny lon 6,6 and 30% glass fiber reinforced ny lon 6,6, E-Journal of chemist ry , 6(1): 23-33. 8.Dongwood ,Jung (2004) ,New methods for p roducing ny lon 6,6 fibers with enhanced mechan ical prop erties, Ph.D thesis, North Carolina st ate University , USA. Table (1): Assignment of FTIR spectrum of ne at nyl on 6,6 Wa ve number (cm -1 ) Absor bance Assignment 3410 3306 3082 2932 2862 1639 1539 1469 1269 1200 934 691 579 0.34 0.38 0.18 0.28 0.25 0.53 0.46 0.31 0.34 0.29 0.17 0.20 0.18 N-H stretching I N-H stretching II C-H stretching (asy m) CH2 st retching (asy m) CH2 st retching (sy m) Amide I st retching Amide II st retching/ CH2 (asy )(mdef) N-H deformation/ CH2 scissoring Amide III st retching CCH bending (sy m)/ CH2 twist ing C-C st retching C-C bendin g C-C deformation Table (2) :Assignment of FTIR spectrum of UV sta bilized nyl on 6,6 Wa ve number (cm -1 ) Absor bance Assignment 3414 3240 2928 2855 1686 1612 1516 1431 1304 1261 1173 1122 1018 922 667 575 0.28 0.14 0.09 0.08 0.19 0.22 0.14 0.15 0.17 0.19 0.16 0.15 0.15 0.05 0.08 0.06 N-H stretching I N-H stretching II CH2 st retching (asy m) CH2 st retching (sy m) Amide I st retching CH2 deformation (asy m) Amide II st retching N-H deformation CH2 wagging Amide III st retching CH2 twisting C-C st retching (sy m) C-C st retching C-C st retching C-C bendin g C-C deformation IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL.24 (1) 2011 Fig.( 1): Chemical structure of nyl on 6,6 Fig.( 2): FTIR s pectrum of neat nylon 6,6 Fig. (3): FTIR s pectrum of UV-stabil ize d nylon 6,6 2011) 1( 24المجلد مجلة ابن الهیثم للعلوم الصرفة والتطبیقیة النظیفة والمستقرة لالشعة فوق 6,6لتشخیص افالم بولیمر نایلون FTIRدراسة البنفسجیة مهدي هند عبدالمجید ابن الهیثم ، جامعة بغداد- قسم الفیزیاء ، كلیة التربیة 2010 اب 22 في استلم البحث 2010 تشرین الثاني 9 في قبل البحث الخالصة ت 6,6 للنایلون یعني العمل بتشخیص افالم مصبوبة النظیفة والمستقرة لالشعة فوق البنفسجیة باستخدام قیاسا النظیف والمستقر لالشعة فوق 6,6تم عمل تعین الحزم لكال من النایلون . FTIRر لالشعة تحت الحمراء فوریتحویل تبین ان اضافة المواد المستقرة لالشعة فوق . التي ثبتت التركیب الجزیئي للبولیمر FTIRالبنفسجیة باستعمال اطیاف د 6,6البنفسجیة إلى النایلون یؤدي إلى نقصان في امتصاصیة حزم االهتزاز وبذلك تؤدي إلى استقرار سلوك البولیمر عن .في البیئات القاسیة یماالساالستخدام