Perugia Giugno 2007 VI CONVEGNO NAZIONALE INSTM SULLA SCIENZA E TECNOLOGIA DEI MATERIALI I.Armentano, M.S. Dottori, D. Puglia, J.M. Kenny Materials Engineering Centre, UdR INSTM, NIPLAB, University of Perugia, Terni, Italy POLY(L-lactide)(PLLA)/SWNT NANOCOMPOSITE FILMS: THERMAL AND MECHANICAL CHARACTERIZATION

THERMAL CHARACTERIZATION T m1 (°C) T cr2 (°C) T m3 (°C) T’ m3 (°C) T g ± 0.4 / ± 0.08 / 55 ± ± ± ± ± 0.7 / ± ± ± ± 2 / Differential Scanning Calorymetry (DSC) (1)χ = ΔHm /ΔHm 0 with ΔHm 0 = 93J/g (5) ; (2) χ 3 = (ΔH 3 - ΔH 3cold ) /ΔHm 0. Materials χ 1 (%) (1) χ 3 (%) PLLA (2) 38.6 ± ± 0.3 PLLA/SWNTs 1% 45.9 ± ± 0.9 PLLA/SWNTs-COOH 1% 47.6 ± ± 2 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.

(2) Dynamo-Mechanical Thermal Analysis (DMTA): 110°C/-10°C Cooling Cycle, 10°C/min. Nitrogen atm. (2) Dynamo-Mechanical Thermal Analysis (DMTA): 110°C/-10°C Cooling Cycle, Cycle Rate = 10°C/min. Nitrogen atm. THERMAL CHARACTERIZATION DSC-DMTA-TGAMaterials T g (°C) (2) T D (°C) (1) PLLA (2) 44.8 ± ± 0.9 PLLA/SWNTs 1% 44.6 ± ± 1 PLLA/SWNTs-COOH 1% 52.5 ± ± 3 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. (1)Thermogravimetric Analysis (TGA): 30°C/1000°C Heating Cycle, Cycle Rate = 10°C/min.; Nitrogen atm.

MECHANICAL CHARACTERIZATION Dynamometric Tensile Test Parameters: Load Cell = 50N; Rate = 5mm/min. TENSILE TEST Materialsε BREAK (%)E YOUNG (MPa) PLLA (2) 88.6 ± ± 20 PLLA/SWNTs 1% 28.9 ± ± 70 PLLA/SWNTs-COOH 1% 57.7 ± ± 40 Adding a few percentage of CNTs, tensile properties have been modified and material becomes more stiff. Failure strain (ε BREAK ) with functionalized CNTs is mantained still high and this is an innovative and positive effect of PLLA/SWNT -COOH interphase. Concerning the bulk behaviour, the enhancement of tensile properties, expecially of Young Modulus, is more pronounced using pristine SWNTs.

NANOINDENTATION (NI) NI Parameters: Depth=1000nm, Load Rate=0.06 mN/s, Load=50mN. MECHANICAL CHARACTERIZATION DYNAMO-MECHANICAL ANALYSIS (DMA) DMA Parameters: Dynamic Time Sweep Test f=1Hz, T=T room, Strain=0.3%, t = 800s.

THANK YOU FOR YOUR ATTENTION. Dr.Ing.Mariaserena Dottori phD Student in “Nanotechnology of Materials”XXI Cycle Materials Engineering Centre, Materials Engineering Centre, UdR INSTM, NIPLAB, University of Perugia, Terni, Italy Tel mail. Acknowledgements STM GROUP INSTM CONSORTIUM THE EUROPEAN COMMISSION AND SIXTH FRAMEWORK PROGRAMME