1. Perugia 12-15 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

2. THERMAL CHARACTERIZATION T m1 (°C) T cr2 (°C) T m3 (°C) T’ m3 (°C) T g3 172.6.± 0.4 / 171.68 ± 0.08 / 55 ± 0.2 167.7 ± 0.3 92.00 ± 0.01 161.3 ± 0.3 151.± 0.7 / 168.2 ± 0.6 112.0 ± 0.9 168 ± 1 159 ± 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 ± 0.7 19.8 ± 0.3 PLLA/SWNTs 1% 45.9 ± 0.9 54.1 ± 0.9 PLLA/SWNTs-COOH 1% 47.6 ± 0.4 57 ± 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.

3. (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 ± 0.9356.3 ± 0.9 PLLA/SWNTs 1% 44.6 ± 0.8357 ± 1 PLLA/SWNTs-COOH 1% 52.5 ± 0.7353 ± 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.

4. MECHANICAL CHARACTERIZATION Dynamometric Tensile Test Parameters: Load Cell = 50N; Rate = 5mm/min. TENSILE TEST Materialsε BREAK (%)E YOUNG (MPa) PLLA (2) 88.6 ± 0.8520 ± 20 PLLA/SWNTs 1% 28.9 ± 0.8820 ± 70 PLLA/SWNTs-COOH 1% 57.7 ± 0.4620 ± 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.

5. 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.

6. 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.+390744492914 mail. mariaserena.dottori@unipg.it Acknowledgements STM GROUP INSTM CONSORTIUM THE EUROPEAN COMMISSION AND SIXTH FRAMEWORK PROGRAMME