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  1. 1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 2, February (2014), pp. 01-07, © IAEME AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 5, Issue 2, February (2014), pp. 01-07 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com IJMET ©IAEME EFFECT OF NANO SiO2 ON SOME MECHANICAL PROPERTIES OF BIODEGRADABLE POLYLACTIC ACID Nadia Abbas Ali1, 1 Ikram Atta AL-Ajaj1, Farah Tariq Mohammed Noori1 Baghdad University, college science, physics Department ABSTRACT Effect of nano SiO2(13.69nm)with different weight percentage (1, 3, 5wt %)on some mechanical properties of polylactic acid (PLA) is investigated .PLA film with thickness 100µm was prepared by solution casting method .Chemical and crystal structure of PLA and its composites with 5% nano SiO2 are characterized by FTIR and X-ray diffraction techniques . Mechanical properties (tensile strength and young modulus) of PLA and its composites are reported .Enhancement in above mechanical properties are observed (35%for tensile strength and 25%for young modulus). The main goal of this work is to study the influence of addition of different silica nanoparticles on the mechanical properties of neat PLA in order to enhance its for brittleness to ductile stage. Key Word: Biodegradable, Polylactic Acid, nano SiO2, Mechanical Properties. 1-INTRODUCTION Natural polymers that are biodegradable and biocompatible has become increasingly important. This is due to their amazing characteristics: natural abundance, low costs and wide range of applications [1]. These polymers are being widely used in the biomedical area, including wound dressing, drug delivery system and tissue engineering scaffolds . Polylactic acid (PLA) is prominent among the polymers that are biodegradable and biocompatible due to versatility of its applications and relatively low cost of production at industrial scale. PLA, is a linear aliphatic thermoplastic polyester, produced from renewable resources, has several attractive properties such as biocompatibility, high strength, and thermo plasticity. It has been used in medical applications, such as surgical sutures, implants, tissue culture, and controlled drug delivery. Though PLA is biodegradable and has been useful in various biomedical applications, the high stiffness and brittleness at ambient temperatures associated with PLA must be improved to allow for more applications [2,3] 1
  2. 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 5, Issue 2, February (2014), pp. 016359(Online), -07, © IAEME The applications of nanomaterial are broad; some of them were used as nano-sensor in smart nano food packaging technology. It also could provide an antimicrobial mechanism by introducing nanonano bulletin active packaging. The most popular purpose of this nano material is widely used as nano reinforcement in composite polymer in fact, many studies on nano reinforcement were reported. mposite Nano-reinforcement that's been studied is such as clay and silicates [4]. reinforcement 2- EXPERIMENTAL WORK 1. Materials Polylactic acid (PLA) (ESUN™ A A-1001) [density = 1.25 g/cm3 was supplied by Bright China Industrial Company. Ltd (Shenzhen, China .NanoSiO2 supplied by Sima-aldrch Company with . aldrch particle size (13.69 nm)is shown in Fig(1)measured by (SPM) of nano SiO2 . s Fig(1) particles Fig(1) Granuality normal distribution chart for nano SiO2 particl 2. Preparation of PLA film and PLA nano SiO2 composites film. PLA/ Neat PLA film is prepared by weight 2gm of PLA in 20 ml of chloroform PLA films chloroform, composites with different weight percentage of nanosilica (1,3,5wt %) were prepared by solution casting method in chloroform. Silica was added in chloroform and stirring in ultrasonic bath for 10 stirr min. Nanoparticles were dispersed in the solvent using ultrasonic bath. Then PLA was added to solvent/silica mixture and stirred with magnetic bar for 4 h hours at 40°C. After dissolving in ed chloroform, PLA/silica nanocomposites were poured into glass Petri dishes (10 cm diameter) and vacuum dried for 2h and, additionally, 24 hours for total evaporation of solvent at room temperature. The films were peeled off with thickness around 100µm. 3. (FT-IR) TEST FT-IR was performed using a Perkin Elmer 1600 Infrared spectrometer. FT-IR spectra of the IR FT IR samples were recorded by using Nicolet’s AVATAR 360 at 32 scans with a resolution of 4 cm and cm-1 within the wave number range of 4000 to 400 cm-1. 4. X-ray Diffraction TEST X-ray Diffraction patterns were measured in a Brüker Advance instrument, at 40 KV, 40 mA using target Cu Kα ( λ= 1.54A° ) with secondary monochromator (Karlsruhe, Germany). Germany) 2
  3. 3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 5, Issue 2, February (2014), pp. 016359(Online), -07, © IAEME 5. Tensile Properties Mechanical test was performed using the Instron 4400 Universal Tester to measure the tensile strength at the point of breakage for each sample. Tensile specimens cut were used were carried out at room temperature, according to the ASTM D-882 as shown in Fig 2a pure PLA , b, c, and d its D a composites(1,3,5wt% ) respectively . A fixed crosshead rate of 10 mm/min was utilized in all cases and the results were taken as an average of five tests. Two metallic grips were attached for griping tests both ends of the test specimen of the film. Tensile strength (σs), Young’s modulus (E) was determined according to the following equation: equation σs =F /(A)……… 1 E =F L0/A L…………2 Where: F: force exerted on an object under tension, L0: original length, A: cross section area, : L: length of the object changes a b c d Fig(2) : samples of PLA and its composites (1,3,5%) nano SiO2 a 3. RESULTS AND DISCUSSION 1. (FT-IR) characterization FT-IR is a well-known and widely used method to investigate the intermolecular interaction known and phase behavior between the polymers. In this study, the interaction between PLA/SiO2 was PLA investigated by FT-IR spectroscopy and is shown in Figure( 3) . FTIR spectrum of neat PLA shown IR Figure in (Fig 3(a)) clearly show the characteristic absorption bands in the region of 3500- 3600 cm-1, absorpt 3500 2946- 2999 cm-1 and 1757cm-1due to O H bending and stretching vibration, C 1due O-H C-H asymmetric stretching vibration and C=O stretching vibration respectively, which agree well with the prepared FTIR of PLA film reported by Cardoso, J. J. F.et. al., [5]. Fig3b is appear of PLA/5%SiO2 which F. bonds of PLA and SiO2 appear that mean good distribution of nano SiO2 in composites film because that bond appear and no different in pure PLA . 3
  4. 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 2, February (2014), pp. 01-07, © IAEME a b Fig(3):FTIR of a :PLA pure, b : PLA /5%SiO2 2.X-ray Diffraction X-ray diffrction pattern of polylactic acid shows two peaks located at 2θ= 16°.5 and 19° with sharp peak for first peak indicating high crystalline structure which agree well with results reported by Batteazzone et.al [6] as reported of PLA finds that pattern of PLA is characterized by a broad band with maximum at 2θ = 16.6º, 19.1° . The XRD pattern of composites (PLA/5%SiO2 ) exhibits broad diffraction peak at 2θ = 22ºdue to addition nano SiO2 for silica which agree well with results reported by A.N. Mohammed et al and find this peak centered at a 2θ = 23◦[7]. 4
  5. 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 5, Issue 2, February (2014), pp. 016359(Online), -07, © IAEME 2θ a 2θ b Fig(4):X-RAY diffraction patterns of a :PLA pure, b :PLA /5%SiO2 SiO 3-Mechanical peoperties Tensile test provides an indication of the tensile strength calculated in eq.1 and young modulus in eq.2 of the films and find both tensile strength and young modulus increased when add nano SiO2 which appear in Fig (5) . .PLA is a biodegradable polymer that has been useful in various biomedical applications. High brittleness that are characteristic of PLA must be improved to allow for more applications [8]. Table 1 shows the values of tensile strength of pure PLA film prepared and its composites films using nanosilica enhanced about 35% and young modulus enhanced about 25% . Mechanical properties of prepared nanocomposites were improved by addition of 5 wt.% of silica comparison to neat PLA matrix, this result agree with ref.[8] is probably due to achievement of good ue dispersion,the mechanical properties of PLA-silica by melt blending found that the tensile strength the PLA silica and modulus of the composites were enhanced by incorporation of nanoparticles. The silica nanoparticles were uniformly distributed in the PLA matrix for filler contents below 5 %·w/w, contents whereas some aggregates were detected with further increasing filler concentration .The mechanical properties of the nano-composites improved because of their degree of dispersion and polymer filler composites interaction. 5
  6. 6. Stress MPa International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 2, February (2014), pp. 01-07, © IAEME 45.0 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 PLA/nano5%SiO2 PLA/nano3%SiO2 PLA/nano1%SiO2 PLA 0.0 2.0 4.0 6.0 8.0 Strain % 10.0 Fig(5):Stress-Strain of PLA and its composites PLA/5%SiO2 Table (1) Mechanical properties of PLA and its composites films Sample Tensile strength(MPa) Young modulus (GPa) PLA 29 2.3 PLA/1%SiO2 32 2.5 PLA/3%SiO2 36 2.9 PLA/5%SiO2 43 3.1 CONCLUSIONS 1- PLAfilm was successfully prepared by casting method. 2- Maximum enhancement in 35%of tensile strength and 25% in young modulus of PLA as observed by adding 5%nano SiO2, due to their good dispersion in PLA matrix. Obtained results could be further used for future research in the field of PLA/silica nanocomposites, as important materials due to their good and satisfying mechanical properties for food packaging application. REFERENCE 123- 4- P. Qu, Y. Goa, G. F. Wu, and L. P. Zhang, (2010) “Nanocomposite of poly(lactid acid) reinforced with cellulose nanofibrils”, J .BioResources , vol. 5(3), 1811-1823. B.K. Chen, T.Y. Wu, Y.M. Chang , A. F. Chen ,(2013)” Ductile polylactic acid prepared with ionic liquids” ,J.Chemical Engineering ,vol. 5 , 215–216. B.H. Li, M.C. Yang,(2006)” Improvement of thermal and mechanical properties of poly(L-lactic acid) with 4,4-methylene diphenyl diisocyanate”, J. Polym. Adv. Technol. Vol.17, 439-443. H.S. Mohd , S. Eraricar , I.M. Ida , N.H. Siti ,(2012) “ Cellouse nanofiber isolation and its fabracication into bio-polymer review “ International Conference on Agricultural and Food Engineering for Life (Cafei2012) 26-28. 6
  7. 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 2, February (2014), pp. 01-07, © IAEME 5- J.J.F. Cardoso, Y..C. Queirós, K.J.A. Machado, J.M. Costa, F.E. ucas, (2013)” SYNTHESIS, CHARACTERIZATION, AND IN VITRO DEGRADATION OF POLY(LACTIC ACID) UNDER PETROLEUM PRODUCTION CONDITIONS” BRAZILIAN JOURNAL OF PETROLEUM AND GAS v. 7 n. 2 , 057-069 6- D. Battegazzore, S. Bocchini, A. Frache,(2011)” Crystallization kinetics of poly(lactic acid)-talc composites” eXPRESS Polymer Letters Vol.5(10),849-85 8. 7- A.N. MOHAMMAD, S. MOHSEN, (2013) “Multi-component reaction on free nano-SiO2 catalyst: Excellent reactivity combined with facile catalyst recovery and recyclability” J. Chem. Sci. Vol. 125(3) , 537-544. 8- R.M. Izan , A.S. Robert , K. Ing ,(2011) ” Melting Behaviour and Dynamic Mechanical Properties of Poly(lactic acid)-Hemp-Nanosilica Composites”, Asian Transactions on Basic and Applied Sciences) ,Vol.3 Issue 2 ,556-561. 9- G .Sanches, R.A.Lopez , J. M. Lagaron ,(2010) “Natural micro and nanobiocomposites with enchaced and novel functionalities for food biopackaging applications”, J.Trends in Food Science & Technology,vol. 21, 528-536 . 10- S.Shankar, Dr.H.K.Shivanand and Santhosh Kumar.S, “Experimental Evaluation of Flexural Properties of Polymer Matrix Composites”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 3, 2012, pp. 504 - 510, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 11- Siddhant Datta, B.M. Nagabhushana and R. Harikrishna, “A New Nano-Ceria Reinforced Epoxy Polymer Composite with Improved Mechanical Properties”, International Journal of Advanced Research in Engineering & Technology (IJARET), Volume 3, Issue 2, 2012, pp. 248 - 256, ISSN Print: 0976-6480, ISSN Online: 0976-6499. 7