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POLY(L-lactide)(PLLA)/SWNT NANOCOMPOSITE FILMS: THERMAL AND MECHANICAL CHARACTERIZATION. I.Armentano, M.S. Dottori , D. Puglia, J.M. Kenny Materials Engineering Centre, UdR INSTM, NIPLAB, University of Perugia, Terni, Italy. VI CONVEGNO NAZIONALE INSTM SULLA SCIENZA E TECNOLOGIA DEI MATERIALI.
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POLY(L-lactide)(PLLA)/SWNT NANOCOMPOSITE FILMS:THERMAL AND MECHANICAL CHARACTERIZATION I.Armentano, M.S. Dottori, D. Puglia, J.M. KennyMaterials Engineering Centre, UdR INSTM, NIPLAB, University of Perugia, Terni, Italy VI CONVEGNO NAZIONALE INSTM SULLA SCIENZA E TECNOLOGIA DEI MATERIALI Perugia 12-15 Giugno 2007
THERMAL CHARACTERIZATION Differential Scanning Calorymetry (DSC) • χ= ΔHm /ΔHm0 with ΔHm0 = 93J/g (5); • (2) χ3= (ΔH3 - ΔH3cold) /ΔHm0 . PLLA matrix does not exhibit melt crystallization. PLLA/CNT nanocomposites exhibit heterogeneous nucleation on SWNT surface, increasing χ. The effect is more pronounced with functionalized CNTs, which anticipate crystallization of about 20°C respect to pristine CNTs, revealing high affinity with PLLA.
DMTA measurements are sensitive to PLLA/CNTs short-range rearrangement on interface. Nanocomposites exhibit higher Tg, that means PLLA and CNTs have a good interface affinity. (2) Dynamo-Mechanical Thermal Analysis (DMTA):110°C/-10°C Cooling Cycle,Cycle Rate = 10°C/min. Nitrogen atm. • Thermogravimetric Analysis (TGA): • 30°C/1000°C Heating Cycle, • Cycle Rate = 10°C/min.; • Nitrogen atm. DSC-DMTA-TGA THERMAL CHARACTERIZATION
MECHANICAL CHARACTERIZATION TENSILE TEST Adding a few percentage of CNTs, tensile properties have been modified and material becomes more stiff. Concerning the bulk behaviour, the enhancement of tensile properties, expecially of Young Modulus, is more pronounced using pristine SWNTs. Dynamometric Tensile Test Parameters: Load Cell = 50N; Rate = 5mm/min. Failure strain (εBREAK)with functionalized CNTs is mantained still high and this is an innovative and positive effect of PLLA/SWNT-COOH interphase.
NANOINDENTATION (NI) NI Parameters: Depth=1000nm, Load Rate=0.06 mN/s, Load=50mN. DYNAMO-MECHANICAL ANALYSIS (DMA) DMA Parameters: Dynamic Time Sweep Test f=1Hz, T=Troom, Strain=0.3%, t = 800s. MECHANICAL CHARACTERIZATION
THANK YOU FOR YOUR ATTENTION. Acknowledgements STM GROUP INSTM CONSORTIUM THE EUROPEAN COMMISSION AND SIXTH FRAMEWORK PROGRAMME Dr.Ing.Mariaserena Dottori phD Student in “Nanotechnology of Materials”XXI Cycle Materials Engineering Centre, UdR INSTM, NIPLAB, University of Perugia, Terni, Italy Tel.+390744492914 mail. mariaserena.dottori@unipg.it