matteo traina , alessandro pegoretti and amabile penati
DESCRIPTION
Università degli Studi di Trento Dipartimento di Ingegneria dei Materiali e Tecnologie Industriali (DIMTI). INSTM Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali. - PowerPoint PPT PresentationTRANSCRIPT
POLYETHYLENE-CARBON BLACK NANOCOMPOSITES: MECHANICAL RESPONSE UNDER CREEP AND DYNAMIC LOADING
CONDITIONS
Matteo Traina, Alessandro Pegoretti and Amabile PenatiUniversity of Trento (DIMTI) and INSTM; Via Mesiano 77, 38050 Trento – Italy
E-mail: [email protected]; On web: www.unitn.it
INSTMConsorzio Interuniversitario Nazionaleper la Scienza e Tecnologia dei Materiali
Università degli Studi di TrentoDipartimento di Ingegneria dei Materiali
e Tecnologie Industriali (DIMTI)
VI CONVEGNO NAZIONALE SULLA SCIENZA E TECNOLOGIA DEI MATERIALI
(June 12th-15th, 2007; Perugia)
INTRODUCTION
agglomerates
primaryparticle aggregate
Carbon black (CB)
Carbon (graphene layers)Combustion or decomposition (CXHY)
OAN (cm3/g)
aggregate structure
SS
A (
m2 /
g)
particle diameter
Microstructure:
primary particles (diameter) specific surface area (SSA) measured by the BET (Brunauer– Emmett–Teller) method (ASTM D 6556-03) TEM analysis
aggregates (structure) oil adsorption number (OAN) measured with the dibuthyl phtalate (ASTM D 2414-04) TEM analysis
Other properties (…)
INTRODUCTION
Grade (Supplier)OAN
[cm3/g]SSA
[m2/g]
CB105 Raven P-FE/B(Columbian Chemicals)
0.98 105
CB226 Conductex 975u(Columbian Chemicals)
1.69 226
CB231 Cabot XC72(Cabot Corporation)
1.78 231
CB802 Ketjenblack EC300J(Akzo Nobel)
3.22 802
CB1353 Ketjenblack EC600JD(Akzo Nobel)
4.95 1,353
Carbon black (CB)
SSA / OAN
SSA / OAN
SSA / OAN
SSA / OAN
INTRODUCTION
CB FILLED COMPOSITES
Matteo Traina, Alessandro Pegoretti and Amabile Penati , Time-temperature dependence of the electrical resistivity of high density polyethylene - carbon black composites. Journal of Applied Polymer Science, in press.
Matteo Traina, Alessandro Pegoretti and Amabile Penati , Processing and Electrical Conductivity of
High Density Polyethylene – Carbon Black Composites. XVII Convegno Nazionale AIM
(Napoli, September 11th – 15st, 2005)
EXPERIMENTAL
HDPE-CB composites
VISCOELASTIC BEHAVIOR Creep tests DMTA tests
COMPOSITE MORPHOLOGYconstant filler content (1 vol%)
Grade (Supplier) Properties
HDPE Eltex A4009(BP Solvay)
MFI = 0.8 g/10min (190°C; 2.16kg)Density = 0.958 g/cm3 (23°C)
MATERIAL (polymeric matrix)
EXPERIMENTAL
HDPE-CB composites
VISCOELASTIC BEHAVIOR Creep tests DMTA tests
COMPOSITE MORPHOLOGYconstant filler content (1 vol%)
Effect of the SSA of CBmatrix HDPEcomposite HDPE-CB226composite HDPE-CB1353
Grade (Supplier)OAN
[cm3/g]SSA
[m2/g]
CB105 Raven P-FE/B(Columbian Chemicals)
0.98 105
CB226 Conductex 975u(Columbian Chemicals)
1.69 226
CB231 Cabot XC72(Cabot Corporation)
1.78 231
CB802 Ketjenblack EC300J(Akzo Nobel)
3.22 802
CB1353 Ketjenblack EC600JD(Akzo Nobel)
4.95 1,353
CB226 CB1353
EXPERIMENTAL
HDPE-CB composites
VISCOELASTIC BEHAVIOR Creep tests DMTA tests
COMPOSITE MORPHOLOGYconstant filler content (1 vol%)
Effect of the SSA of CBmatrix HDPEcomposite HDPE-CB226composite HDPE-CB1353
PROCESSING
Melt compounding (Extrusion)Twin screw extruder(ThermoHaake PTW16)T = 130-200-210-220-220°Cn = 12 rpm
Effect of the degreeof filler dispersionMultiple extrusions(up to 3 times)
FILLER DISPERSION
Extrusions 3x
HDPE-CB1353
500 µm
HDPE-CB226
2x1x
HDPE-CB composites >>> thin section (microtome) >>> optical microscope
As the number of extrusions increases,as the degree of the filler dispersion is better.
As the S
SA
decreases, as the degree of dispersion is better.
HDPE-CB226, 1x
HDPE-CB composites>>> ultra-thin section (cryo-ultramicrotome) >>> transmission electron microscope
>>> PRELIMINARY RESULTS
HDPE-CB226, 2x
CB226
FILLER DISPERSION
As the number of extrusions increases,as the degree of the filler dispersion is better.
MOLECULAR WEIGTH DISTRIBUTION
HDPESize Exclusion Chromatography (SEC)1,2,4 trichlorobenzene (TCB) at 140°C
IP
MW
HDPEHDPE-CB
The HDPE undergoes a progressive thermo-mechanical degradation during the extrusion processes.
EFFECT OF MULTIPLE EXTRUSIONS: 3x > 2x > 1x HDPE > HDPE-CB226 > HDPE-CB1353
EFFECT OF THE FILLER: HDPE > HDPE-CB226 > HDPE-CB1353 3x > 2x > 1x
CREEP: GENERAL COMPARISON
Creep tests: 30°C, 10 MPa
extruded 1x
extruded 2x extruded 3x
HDPE-CB composites
VISCOELASTIC BEHAVIOR Creep tests DMTA tests
COMPOSITE MORPHOLOGYconstant filler content (1 vol%)
Effect of the SSA of CBmatrix HDPEcomposite HDPE-CB226composite HDPE-CB1353
Effect of the degreeof filler dispersionMultiple extrusions(up to 3 times)
HDPE 1xHDPE 2xHDPE 3x
HDPE-CB226, 1xHDPE-CB226 2xHDPE-CB226 3x
HDPE-CB1353 1xHDPE-CB1353 2xHDPE-CB1353 3x
DEGRADATION PHENOMENAHDPE, 1xHDPE, 3x
HDPE 1xHDPE 3xHDPE-CB226 3xHDPE-CB1353 3x
FILLER EFFECTHDPE, 3xHDPE-CB226, 3xHDPE-CB1353, 3x
CREEP RESISTANCE
DEGRADATION:HDPE 3x < HDPE 1x
FILLER EFFECT:HDPE < HDPE-CB226 < HDPE-CB1353
These effects are evident at long time,while at short time the curves are almost superimposed.
CREEP: MASTER CURVES
HDPE-CB @ 30°C
HDPE @ 30°CCreep test:temperature = 3090°Cstress = 3 MPa (linear viscoelasticity)
ANALYSIS OF THE DATA:Time-Temperature Superposition Principle(temperature spectrum master curve)
LOG-linear
IN GENERAL: linear decreasing in bi-logarithmic scale the most differences is present at short time (<105 s) at long time (>105 s) the curves are superimposed
CREEP: CREEP RATE
Master curves linear viscoelasticityCreep tests constant load/stress LOG-LOG
LOG-LOG
dt
dt
strain rate:dt
dDD
Creep rate
AT SHORT TIME:
DEGRADATION: HDPE 3x > HDPE 1x
FILLER EFFECT: HDPE > HDPE-CB226 > HDPE-CB1353)
CREEP: RETARDATION SPECTRA
HDPE-CB @ 30°C
HDPE @ 30°C
ttd
tDdDL
log
log
The retardation spectrum translates:
DEGRADATION:HDPE 3x < HDPE 1x
FILLER EFFECT:HDPE < HDPE-CB226 < HDPE-CB1353
Linear viscoelasticity:es. Maxwell generalized modelretardation time distribution
Retardation spectrum (first-order approximation)
The elastic components don’t change in a meaningful way.
CREEP: ISCOCHRONOUS COMPLIANCE
Comparison of the isochrone compliance (@ 2000s) as a function of the temperature
The compliance is divided in: elastic component (instantaneous), DE
viscoelastic component (time dependent), DV
HDPE @ 2000s, DV
HDPE-CB @ 2000s, DV
D(t=2000) = DE + DV
DE = D(t=0s)DV = D(t=2000s) – D(t=0s)
The viscoelatic components:
DEGRADATION:HDPE 3x > HDPE 1x (<70°C)
FILLER EFFECT:HDPE > HDPE-CB226 > HDPE-CB1353
Glass transition temperature:
DEGRADATION:HDPE 3x < HDPE 1x (-10°C)
FILLER EFFECT:HDPE < HDPE-CB (+4°C)
DMTA: GENERAL COMPARISON
Material Tg=T [°C]
HDPE, 1x -98.8
HDPE, 3x -108.9
HDPE-CB226, 3x -104.3
HDPE-CB1353, 3x -103.8
DMTA tests:temperature = -130 130°Cfrequency = 1 Hz
Relaxation phenomena (, )
DMTA: MASTER CURVES
HDPE-CB @ 30°C
HDPE @ 30°CDMTA test:temperature = -20130°C ( relaxation)frequencies = 0.330 Hz
ANALYSIS OF THE DATA:Time-Temperature Superposition Principle(temperature spectrum master curve)
The DMTA results are analogous to the CREEP results.
Storage modulus:
DEGRADATION:HDPE 3x < HDPE 1x
FILLER EFFECT:HDPE < HDPE-CB226 < HDPE-CB1353
The relaxation spectra (DMTA) are consistent with the retardation spectra (CREEP) and very similar to the MWD data for the HDPE.
DMTA: RELAXATION SPECTRA
HDPE-CB @ 30°C
HDPE @ 30°C
Linear viscoelasticity:
Relaxation spectrum (first-order approximation)
1
log
log
d
EdEH
DEGRADATION:HDPE 3x >narrow> HDPE 1x
FILLER EFFECT:longer relaxation times for HDPE-CB
ACTIVATION ENERGY
ACTIVATION ENERGY of “” relaxation [kJ/mol] various method of calculation
250 255 260 265 270 275
HDPE, 1x
HDPE, 3x
HDPE-CB226, 3x
HDPE-CB1353, 3x
\
0 50 100 150 200 250
HDPE, 1x
HDPE, 3x
HDPE-CB226, 3x
HDPE-CB1353, 3x
\
CREEPshift factor
(Arrhenius equation)
DMTAshift factor
at high temperature(50100°C)
(Arrhenius equation)
DEGRADATION:HDPE 3x < HDPE 1x
FILLER EFFECT:HDPE < HDPE-CB
CONCLUSIONS
The creep resistance (in general the viscoelastic behaviour) of the HDPE-CB composites is strictly dependent:
● on the CB type as the SSA increases as the creep resistance increases >>> The filler-matrix interaction hamper the chain motions
elastic/viscoelastic components of complianceactivation energy, retardation/relaxation spectracreep rate.
● on the level of dispersion of the filler in the polymer matrix as the filler dispersion is improved as the creep resistance increases >>> The improved dispersion enhances the filler-matrix interaction, i.e. the effective surface area.
● on the degradation of the polymer matrix as the matrix degrades as the creep resistance decreases