Melt compounding of thermoplastic polymers with carbon nanotubes

Melt compounding of thermoplastic polymers with carbon nanotubes

Melt compounding of thermoplastic
polymers with carbon nanotubes
Petra Pötschke, Sven Pegel, Andreas Janke
Leibniz Institute of Polymer Research Dresden
Hohe Str. 6, 01069 Dresden, Germany
Ingo Alig, Sergej M. Dudkin
Deutsches Kunststoff- Institut
Schlossgartenstr. 6, 64289 Darmstadt, Germany
Workshop Dresden January 2005
Outline
1. Introduction
2. Composites of multiwalled carbon nanotubes (MWNT) with polycarbonate (PC)
produced by masterbatch dilution technique
• Electrical resistivity
• Dispersion and alignment
• Influence of processing parameters on electrical resistivity
3. Composites of MWNT and SWNT with PC produced by direct incorporation
• Percolation of different commercial MWNT in PC
• Percolation of SWNT in PC
• Stress-strain behaviour
4. Summary and Thanks
Workshop Dresden January 2005
Benefits of carbon nanotubes (CNT) to polymers
• Electrical conductivity
• Improvement of mechanical properties, especially strength
• Enhancement of thermal stability
• Enhancement of thermal conductivity
• Improvement of fire retardancy
• Enhancement of oxidation stability
Effects at low CNT contents because of the very high aspect ratio
How to introduce nanotubes into polymers
Problem: Deagglomeration and dispersion
MWNT are produced as agglomerates
SWNT are produced as bundles
• Suspensions of nanotubes in polymer solutions, preparation as thin
films
• In-situ polymerization in presence of nanotubes
• Melt mixing of nanotubes with polymers
Melt mixing of CNT with thermoplastic polymers
Starting from a masterbatch
Direct incorporation
Highly concentrated batch of polymer
with 15-20 wt% CNT
From solid premixtures of polymer
powders/granules with CNT
Commercially avalaible, p.e. Hyperion
Catalysis Intern. Cambridge, USA
Safety issues have to be considered
Tasks
Distribution
Dispersion
masterbatch
Wetting of the CNT by polymer
•Surface characteristics and
interfacial tension polymer-CNT
•Melt viscosity of the polymer
CNT
nanocomposite
Pure polymer
Pure polymer
Preparation of the PC-MWNT composites
Masterbatch technology: polycarbonate (PC) + PC based masterbatch
(15 wt% MWNT)
• masterbatch (Hyperion Catalysis International, Inc, Cambridge, USA) diluted with
PC Iupilon E2000 (PC1), PC Lexan 121 (PC2) or PC as used for the masterbatch (PC3)
• Haake co-rotating, intermeshing twin screw extruder with one kilogramm mixtures
• DACA Micro Compounder, conical twin screw extruder (4.5 cm3 capacity)
• Brabender PL-19 single screw extruder
Characterization of the masterbatch (PC + 15 wt% MWNT)
AFM of cut surface
100 nm
SEM of fracture surfaces, no sputtering
Dispersion in PC-MWNT composites
1 wt% MWNT
2 wt% MWNT
5 wt% MWNT
Extrusion direction
Transmission electron microscopy
• all samples are well dispersed,
• and do not show agglomerates
• however, percolation is detectable
• no indication of MWNT alignment
Pötschke, Bhattacharyya, Janke
Eur. Polym. J. 40 (2004)1, 137-148
Thin section (200 nm, defocusing contrast)
Alignment in PC-MWNT composites
Transmission electron microscopy
fiber axis
PC + 2wt% MWNT (cut along strand or fiber direction):
Extruded strand
melt spun fiber (draw speed 800 m/min)
Comparison: different sets with PC masterbatches
Masterbatch dilution performed at Hyperion:
PC Hyperion
Dilution using DACA Micro Compounder:
Masterbatch dilution using:
PC E 2000 (powder)
PC Hyperion (granules)
PC Hyperion (powder)
PC Lexan 121 (granules)
Dilution using Brabender Single-screw extruder:
PC Lexan 121 (granules)
Volume resistivity (Ohm cm)
17
10
14
10
11
10
8
10
5
10
2
10
-1
10
0
1
2
3
4
5
6
7
Content of MWNT (wt%)
- full symbols measured with 8009A Resistivity Test Fixture, compression molded plates d= 60 mm, thickness 0.35mm
- open symbols measured with four-point-method on small strips 10x3x0.35mm (cut from the sheets)
Detection of percolation and influence of processing
conditions investigated by dielectric spectroscopy
-5
10
-3
10
-1
10
1
3
10
5
10
10
10
1
10
0
10
8
10
6
10
4
10
2
10
0
10
-2
10
2
ε''
10
10
10
4.0, 5.0
-2
10
-6
10
1.0
-10
10
10
-3
10
-1
10
1
10
10
5
10
4
10
2
10
0
10
-2
10
10
Frequency, Hz
prepared at 260°C, 150 rpm, 5 min
2
ε'
1
0
8
6
4
2
10
0
10
10
7
10
10
-2
-14
3
6
10
-18
-5
10
-2
10
-18
8
10
-10
0
10
4
10
0,5
-14
10
0
10
-6
7
10
10
6
10
5
10
1
10
-2
NT% rpm min
1,5 50 15
1,5 150 5
1,5 150 15
-2
10
3.0
2.0
1.5
3
10
10
8
0
10
1
10
10
10
2
10
-1
10
2
0
ε''
10
-3
10
10
σ' S/cm
ε'
1
10
10
σ' S/cm
10
2
10
10
-5
7
10
-6
10
-2
10
-6
10
-10
-10
10
10
1,0 150 15
1,0 50 15
1,0 150 5
-14
10
-14
10
-18
10
-18
-5
10
-3
10
-1
10
1
10
3
10
5
10
10
7
10
Frequency, Hz
variation of mixing conditions
real part ε‘, imagionary part ε‘‘, and AC conductivity σ‘ for composites prepared from PC 2
and masterbatch using DACA Micro Compounder (Pötschke, Dudkin, Alig: Polymer,44(2003) 5023)
Direct incorporation of commercial MWNT into PC
Volume resistivity (Ohm cm)
MWNT2 = MWNT very thin straight and coiled, purity >60% (crude), diameter 5…(10)...15 nm
MWNT3 = MWNT very thin straight and coiled, purity >95% (purified), diameter 5…(10)...15 nm
Nanocyl S.A. (Namur, Belgium), produced by CVD
MWNT4 = TsNA-MWCnt1, purity >80%, diameter <10 nm
Tsinghua-Nafine Nano-Powder Commercialization Engineering Center (TNNPCEC) Beijing, China
10
18
10
15
10
12
10
9
10
6
10
3
10
0
MWNT2 (Nanocyl, very thin crude)
MWNT3 (Nanocyl,very thin purified)
MWNT4 (TsNaMWCnt1, C-nano, China)
• PC = PC Iupilon E 2000
(6800 Pa-s at 260°C)
• Mixing using DACAMicrocompounder at
280°C, 50 rpm, 15 min
Pötschke et al. Fullerenes,
Nanotubes, and Carbon
Nanostructures (2005), in press
0
1
2
3
4
Content of MWNT in PC (wt%)
5
6
full symbols measured with 8009A
Resistivity Test Fixture on 60 mm
sheets, open symbols measured with
four-point-method on small strips
10x3x0.35mm
Volume resistivity (Ohm cm)
Comparison of direct incorporation of CNT,
masterbatch dilution, and CB addition
10
18
10
15
10
12
10
9
10
6
10
3
10
0
MWNT Hyperion (masterbatch dilution)
MWNT2 (Nanocyl, very thin crude)
MWNT3 (Nanocyl,very thin purified)
MWNT4 (TsNaMWCnt1, C-nano, China)
DWNT, Nanocyl purified
CB Vulcan XC-72 (Cabot)
CB Ketjenblack 300J (Akzo-Nobel)
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
Content of carbon filler in PC (wt%)
• full symbols :8009A Resistivity Test Fixture on 60 mm sheets (thickness 0.35 mm) combined with Keithley 6517A
• open symbols: four-point-method on small strips 10x3x0.35mm combined with Keithley DMM 2000
Direct incorporation of SWNT1 into PC
• SWNT produced at MPI Stuttgart (AG Dr. Roth)
• unpurified arc-discharge material, dSWNT 1.0-1.3 nm, bundled
• PC = PC Iupilon E 2000 (6800 Pa-s at 260°C)
• Mixing using DACA-Microcompounder at 280°C, 50 rpm, 15 min
G-band
intensity (arb. units)
8000
6000
4000
Radial breathing mode
(RBM)
D-band
2000
0
0
500
1000
1500
2000
-1
SEM of a buckypaper
Raman shift (cm )
2500
3000
Volume resistivity (Ohm cm)
Direct incorporation of SWNT1 into PC
10
19
10
18
10
17
10
16
10
15
10
14
10
13
10
12
10
11
10
10
10
9
10
8
10
7
10
6
10
5
10
4
10
3
DC
0
1
2
3
4
5
6
7
8
C o n te n t S W N T (w t% )
2
10
1
10
0
ε'
10
SEM fractured sample 4wt% SWNT1
σ' [S/cm]
ε''
10
AC
10
10
8
10
6
10
4
10
2
10
0
10
-2
10
-3
10
-5
10
-7
10
-9
10
-1 1
10
-1 3
10
-1 5
10
-1 7
10
7 .5
5
4
3
2
1
0
-3
10
-1
10
1
10
3
F r e q u e n c y [H z ]
10
5
10
7
Direct incorporation of SWNT1 into PC
40
PC
PC + 1% SWNT
PC + 2% SWNT
PC + 3% SWNT
PC + 4% SWNT
PC + 5% SWNT
PC + 7.5% SWNT
30
20
10
0
0
50
100
Strain (%)
Pötschke et al. AIP Conference
Proceedings 723 (2004) 478
800
600
40% increase
400
0
1
2
3
4
5
6
7
8
content of SWNT (wt%)
65
100
60
σ yield
σ break
55
ε break
50
45
80
60
40
20
40
0
0
1
2
3
4
5
6
7
content of SWNT (wt%)
8
elongation at break (%)
Stress (MPa)
50
stress (MPa)
60
Young modulus (MPa)
1000
Direct incorporation of SWNT2 into PC
• SWNT2= commercial SWNT from CNI
Houston (TX, USA) delivered as buckypearls
• produced using high pressure
decomposition of carbon monoxide
supported by a Fe catalyst (HiPCO)
According to CNI:
• metallic impurity level 5%
• of the carbon, more than 95% SWNT
• mean diameter is about 1 nm, lengths
between 0.3 and 1 µm, organized in ropes
intensity (counts)
80000
G
SWNT CNI
60000
D*
40000
20000
RBM
D
0
3000
2500
2000
1500
1000
-1
Raman shift (cm )
500
Ropes of SWNTs, 10 – 80 nm wide
Diameter of the SWNTs ~ 1 nm
Catalyst particles - iron or iron oxide (EDS)
TEM by Dr. M. C. Bunescu , TU Wismar
Philips CM200, equipped with EDAX system
Direct incorporation of SWNT2 into PC
• PC = PC Iupilon E 2000 (6800 Pa-s at 260°C), processing at 280°C, 50 rpm, 5 min
Volume resistivity (Ohm cm)
• SWNT2 as delivered (buckypearls)
• SWNT2 predispersed in acetone under ultrasonification for 3 min, solvent removal,
premixture of small pieces of the mat and PC added to the running compounder
10
18
10
15
10
12
10
9
10
6
10
3
10
0
SWNT2-PC powder premixtures
SWNT2 pretreatment in acetone
0,0
0,2
0,4
0,6
0,8
1,0
1,2
Content of SWNT (wt%)
1,4
1,6
Percolation
between 0.30 and
0.35 wt% SWNT !
Pötschke et al. Fullerenes,
Nanotubes, and Carbon
Nanostructures (2005), in press
Summary and Thanks
Melt mixing is a powerful method to disperse CNT into polymers
Masterbatch dilution technique (based on a PC masterbatch)
• percolation in the range of 1.0 wt% MWNT
• suitable processing conditions can shift percolation to lower values (0.5wt%)
• effects of mixing equipment and PC viscosity on percolation are small
Direct incorporation method
• percolation strongly depends on the kind of CNT, production method (resulting in
different sizes, purity and defect levels), and the purifying/modification steps
• for commercial MWNT percolation occurs between 1.0 and 3.0 wt% and is lower at
lower MWNT diameters and higher purity
• HipCO-SWNT (CNI) percolation between 0.30 and 0.35 wt%
• stress-strain behavior of the composites: modulus and stress are
enhanced, elongation at break reduced especially above percolation concentration
Thanks to:
• Hyperion Catalysis International, Inc (Cambridge, USA) for supplying PC and masterbatch
• German Federation of Industrial Cooperative Research Associations "Otto von Guericke" (AIF) for
financial support of parts of this work within the project 122ZBG
• Nanofunpoly – Network of Excellence
Thanks to
IPF:
• technicians : Monike Henze, Helfried Kunath (mixing)
• Post-docs: A.R. Bhattacharyya , M. Abdel-Goad (rheology)
• scientists: S. Pegel (phd, mixing, SEM), L. Häußler (DSC, TGA)
Cooperations:
• A. Leonhardt (IFW Dresden, MWNT material, SEM of composites)
• S. Roth, B. Hornbostel (MPI Stuttgart, SWNT material)
• O. Decroly (Nanocyl S.A. Belgium, MWNT materials)
• M. C. Bunescu , TU Wismar (TEM)