Photonic crystals in biology - NanoTR-VI

PPPoster Session, Thursday, June 17Theme F686 - N1123The Effect of Nanometer Size Mica Fillers on Mechanical Properties of Polyurethane112UAysel Ersoy YilmazUP P*, Ayten KuntmanP Pand Bulent AydemirP1PDepartment of Electrical-Electronics Eng, Istanbul University, Istanbul 34380, Turkey2PTubitak UME, National Metrology Institute, Gebze, Kocaeli 41470, TurkeyAbstract-In this study mechanical properties of nanometer size mica added polyurethanes were investigated experimentally. At first micaparticles at 1 nanometer size were prepared, and then polyurethane samples with different nanometer size mica concentrations were prepared.Except 10 % mica filler concentrations the resulting nano composites compressive strength is increased.Today in many engineering applications, more than oneclass of materials is used together. At this point additives andfillers gain extra importance due to their significant impact onelectrical, thermal, mechanical and environmental propertiesof the resulting composite. Polyurethanes have a wide rage ofapplications including coatings, adhesives, fibers, thermalinsulator, electrical insulators, etc. However they have somedisadvantages such as low mechanical strength, low thermalstability, low electrical properties, etc. During the last decadeseveral studies has been done to improve these propertiesusing nano size particles [1-5].In this study polyurethane nano composite with various micaconcentrations is studied. To investigate the change inmechanical properties compressive strength tests were doneaccording to the ASTM D1621-04a standard.In this study micas were modified with aminolauric acid andthe preparation procedure was briefly given. Biotite(KMg2.5Fe2+0.5AlSi3O10(OH)1.75F0.25 ) which has adensity of 2,9 g/cm3 is used as mica filler. To a suspension ofaminolauric acid (8.61 g, 40 mmol) in 1,000 ml distilledwater, concentrated HCl (4.17 g, 40 mmol) was added. Themixture was stirred at 80 C until getting a clear solutionindicating the formation of ammonium salt. To this solution, asuspension of 20 g of mica in 1,000 ml of distilled water wasadded with mechanical stirring at 80 C. The stirring wascontinued over night. The resulted white precipitate wascollected by suction filtration. The precipitate was suspendedin hot distilled water with mechanical stirring for 1 h toremove the adsorbed salts. This process was repeated severaltimes until no chloride ions were detected in the filtrate whenadding 0.1 M AgNO3. The precipitate was dried in a ventedoven at 60 oC for 3 days and then at 80 oC under 0.01 atm.vacuum for 24 h.All the polyurethane nano composite samples were preparedunder the same laboratory conditions. The desired weights ofpolyurethane, mica and %0.01 Di butyltin dilaurate catalystwas mixed for 5 minutes. Then the mixture was heated to 100oC and 25% polymeric (methylenediphenylene diisocyanate)MDI was added. The new blend was poured into the mouldand pressed for 10 minutes with the help of clamps. Mouldwas placed in a degasser under high vacuum to remove any airand potentially water vapor from the system. 24 h later themould was opened and the samples were cut in the dimensionsof 1mm by 50mm by 50mm. The highest content of mica inpolyurethane samples was limited to 10 % by weight for nanofillers due to dispersion and processing problems.The mechanical tests to determine compressive strength werecarried out on samples prepared according to the ASTMD1621-04a standard. The experiments were carried out with aZwick tensile test machine at National Metrology Institute inTUBITAK. For the compressive strength tests, the sampleswere shaped into 12.3 mm diameter, 25.4 mm long cylinders.The test parameters can be adjusted with TestXpert software.Tests were performed at a speed of 1.00 mm/min. All testswere performed at 23 C (room temperature).Table 1. Compressive strength test results for 1 nm particle sizeMaterial Type Compressive Strength (GPa)Pure PU 9,056PU+%1 11,426PU+%3 11,600PU+%5 9,541PU+%10 7,816The preparation of PU nanocomposite foams were describedin this study. Clay dispersion is affect by chemical process.With the inclusion of 3% micas, nanocomposite show asmaller cell size than pure polyurethane samples. Dependingon the chemical structure of polyurethane, as high as 28%increase in compressive strength were observed in PU-micananocomposite. However increasing the filler content to 10%mica concentration opposite effect was observed in PUnanocomposite 13.6% decrease in compressive strength wereobserved. Preparation of polyurethane nanocomposite is acomplicated process where many factors could effect bubblenucleation and bubble growth and in turn the compressivestrength. For applications in electrical insulators, compressivestrength is a very important property to calculate the mass ofcover material upon the bare cable conductor. According tothe results from this study cell size in polyurethane nanocomposite is decreased and compressive strength isremarkably increased at 3% mica addition. However detailedmechanism on how nano size mica particles affect mechanicalproperties of polyurethanes needs further investigation.*Corresponding author: aersoy@istanbul.edu.tr[1] R. A. C. Altafim, C. R. Murakami, S. C. Neto, L. C. R. Araújo,G. O. Chierice, “The Effects of Fillers on Polyurethane Resin-basedElectrical Insulators”, Materials Research, Vol 6, No 2, pp. 187-191,2003.[2] X. Cao, L. J. Lee, T. Widya, C. Macosko, “Polyurethane/claynanocomposites foams: processing, structure and properties”,Polymer , Vol. 46, pp.775-783, 2005.[3] J.H. Chang, Y. U. An, “Nanocomposites of Polyurethane withVarious Organoclays: Thermomechanical Properties, Morphology,and Gas Permeability”, Journal of Polymer Science: Part B: PolymerPhysics, Vol. 40, pp. 670–677, 2002 .[4] F. Saint-Michel, L. Chazeau, J.-Y. Cavaille, “Mechanicalproperties of high density polyurethane foams: II Effect of the fillersize”, Composites Science and Technology Vol. 66, pp. 2709–2718,2006. .[5] K.J. Yao, M. Song, D.J. Hourston, D.Z. Luo, “Polymer/layeredclay nanocomposites: 2 polyurethane nanocomposites”, PolymerCommunication, Vol. 43, pp.1017-1020, 2002.6th Nanoscience and Nanotechnology Conference, zmir, 2010 729