Perugia 12-15 Giugno 2007Perugia 12-15 Giugno 2007

VI CONVEGNO NAZIONALE INSTM VI CONVEGNO NAZIONALE INSTM SULLA SCIENZA E TECNOLOGIA SULLA SCIENZA E TECNOLOGIA DEI MATERIALIDEI MATERIALI

I.Armentano, I.Armentano, M.S. DottoriM.S. Dottori, D. Puglia, J.M. Kenny, D. Puglia, J.M. Kenny  Materials Engineering Centre, UdR INSTM, NIPLAB, Materials Engineering Centre, UdR INSTM, NIPLAB,

University of Perugia, Terni, ItalyUniversity of Perugia, Terni, Italy

POLY(L-lactide)(PLLA)/SWNT POLY(L-lactide)(PLLA)/SWNT NANOCOMPOSITE FILMS:NANOCOMPOSITE FILMS:

THERMAL AND MECHANICAL THERMAL AND MECHANICAL CHARACTERIZATIONCHARACTERIZATION

THERMAL CHARACTERIZATIONTHERMAL CHARACTERIZATION

TTm1m1(°C)(°C) TTcr2cr2(°C)(°C) TTm3 m3 (°C)(°C) T’T’m3 m3 (°C)(°C) TTg3g3

172.6.± 0.4172.6.± 0.4 // 171.68 ± 0.08171.68 ± 0.08 // 55 ± 0.255 ± 0.2

167.7 ± 0.3167.7 ± 0.3 92.00 ± 0.0192.00 ± 0.01 161.3 ± 0.3161.3 ± 0.3 151.± 0.7151.± 0.7 //

168.2 ± 0.6168.2 ± 0.6 112.0 ± 0.9112.0 ± 0.9 168 ± 1168 ± 1 159 ± 2159 ± 2 //

50 100 150

-1

0

1

T(°C)

Cooling Cycle 2Flow

Rat

e [m

W]

Heating Cycle 3

1-2-3 Cycles (-25°C/250°C)Rate Cycle = 10°C/min.

Nitrogen atm.

Differential Scanning Calorymetry Differential Scanning Calorymetry (DSC)(DSC)

(1)(1) χχ = = ΔΔHm /Hm /ΔΔHmHm00 with with ΔΔHmHm00 = 93J/g = 93J/g (5)(5); ; (2) (2) χχ33= (= (ΔΔHH33 - - ΔΔHH3cold3cold) /) /ΔΔHmHm0 0 ..

MaterialsMaterials χχ1 1 (%)(%)(1)(1) χχ3 3 (%) (%)

PLLAPLLA(2)(2) 38.6 ± 0.738.6 ± 0.7 19.8 ± 19.8 ± 0.30.3

PLLA/SWNTs 1%PLLA/SWNTs 1% 45.9 ± 0.945.9 ± 0.9 54.1 ± 54.1 ± 0.90.9

PLLA/SWNTs-COOH 1%PLLA/SWNTs-COOH 1% 47.6 ± 0.447.6 ± 0.4 57 ± 257 ± 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 (2) Dynamo-Mechanical Thermal Analysis (DMTA):Thermal Analysis (DMTA):

110°C/-10°C Cooling Cycle,110°C/-10°C Cooling Cycle, Cycle Rate = 10°C/min. 10°C/min.

Nitrogen atm.Nitrogen atm.1 10 100

T(°C)

Tan

a.

u.

Cooling Cycle(110°C/-10°C)Cooling Rate = 10°C/min.Nitrogen atm.

THERMAL CHARACTERIZATIONTHERMAL CHARACTERIZATIONDSC-DMTA-TGADSC-DMTA-TGA

MaterialsMaterials Tg(°C) (2) TD(°C)(1)

PLLAPLLA(2)(2) 44.8 ± 0.9 356.3 ± 0.9

PLLA/SWNTs 1%PLLA/SWNTs 1% 44.6 ± 0.8 357 ± 1

PLLA/SWNTs-COOH 1%PLLA/SWNTs-COOH 1% 52.5 ± 0.7 353 ± 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)(1)Thermogravimetric Analysis (TGA):Thermogravimetric Analysis (TGA):30°C/1000°C Heating Cycle, 30°C/1000°C Heating Cycle, Cycle Rate = 10°C/min.;Cycle Rate = 10°C/min.;Nitrogen atm.Nitrogen atm.

MECHANICAL CHARACTERIZATIONMECHANICAL CHARACTERIZATION

PLLA PLLA/SW PLLA/SW-COOH0

10

20

30

0

10

20

30

Yield Strength [MPa] Yield Strain [%] Tensile Strength [MPa]

Stra

ins [

%]

Stre

ngth

[MPa

]

1% reinforced PLLA

Dynamometric Tensile Test Parameters: Dynamometric Tensile Test Parameters: Load Cell = 50N; Rate = 5mm/min.Load Cell = 50N; Rate = 5mm/min.

TENSILE TESTTENSILE TEST

MaterialsMaterials εBREAK(%) EYOUNG(MPa)

PLLAPLLA(2)(2) 88.6 ± 0.8 520 ± 20

PLLA/SWNTs 1%PLLA/SWNTs 1% 28.9 ± 0.8 820 ± 70

PLLA/SWNTs-COOH 1%PLLA/SWNTs-COOH 1% 57.7 ± 0.4 620 ± 40

Adding a few percentage of CNTs, tensile properties have been modified and material becomes more stiff.

Failure strain (εBREAK) 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.

PLLA PLLA/SW PLLA/SW-COOH0,0

0,5

1,0

1,5

2,0

2,5

3,0

Stiff

ness

Pro

pert

ies [

GPa

]

1% reinforced PLLA

DMA Shear Modulus[GPa] NI Elastic Modulus[GPa]

NANOINDENTATION (NI)NANOINDENTATION (NI)NI Parameters:NI Parameters:

Depth=1000nm, Load Rate=0.06 mN/s, Depth=1000nm, Load Rate=0.06 mN/s, Load=50mN.Load=50mN.

MECHANICAL CHARACTERIZATIONMECHANICAL CHARACTERIZATION

DYNAMO-MECHANICAL ANALYSIS DYNAMO-MECHANICAL ANALYSIS (DMA)(DMA)

DMA Parameters:DMA Parameters:Dynamic Time Sweep TestDynamic Time Sweep Test

f=1Hz, T=Tf=1Hz, T=Troomroom, Strain=0.3%, t = 800s., Strain=0.3%, t = 800s.

THANK YOU FOR THANK YOU FOR YOUR ATTENTION.YOUR ATTENTION.

Dr.Ing.Mariaserena DottoriDr.Ing.Mariaserena DottoriphD Student in “Nanotechnology of Materials”XXI CyclephD Student in “Nanotechnology of Materials”XXI Cycle

  Materials Engineering Centre, Materials Engineering Centre, UdR INSTM, NIPLAB, UdR INSTM, NIPLAB,

University of Perugia, Terni, ItalyUniversity of Perugia, Terni, Italy

Tel.+390744492914Tel.+390744492914

mail. mariaserena.dottori@unipg.itmail. mariaserena.dottori@unipg.it

AcknowledgementsAcknowledgements STM GROUPINSTM CONSORTIUMTHE EUROPEAN COMMISSION AND SIXTH FRAMEWORK PROGRAMME