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Physical & Chemical properties

Nanomaterial aspect ratio / shape

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Administrative data

Endpoint:
nanomaterial aspect ratio/shape
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010-2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: internal method ASM.MDA.023
Principles of method if other than guideline:
ASM.MDA.023: "Qualitative characterization of Cabon Nanotubes by transmission electron microscopy".
Transmission electron microscopy allows to observe all types of thin samples (thickness: 20 -60 nm) or powders and to give information about morphology at the micrometric scale up to the nanometric scale.
TEM is here applied to the qualitative characterization of carbon nanotubes : configuration of nanotube ends, branching, alignmement of nanotubes along long axis.
GLP compliance:
no
Other quality assurance:
other: ISO 9001 Standard
Type of method:
transmission electron microscopy
Details on methods and data evaluation:
A microscopiy copper grid covered with a carbon film with holes is plunged into a suspension of CNT in ethanol.
After evaporation of ethanol, the TEM grid is installed on a sample holder and is introduced into the microscope column at the level of the objective lens.
The TEM grid can be observed under a 200kV voltage. The magnifications range is used from 2000 times up to 66000 times according to the wished information.
For difficult examinations of the ends and branching in CNT and for the search of a possible directional axis in CNT, diluted solutions are preferably prepared and magnifications range can be from 44000 up to 100000 times.
For the study of CNT ends, about 10 -20 photos are examined on one TEM grid, all the visible ends (between 150 and 400) are counted and the proportion of closed ends and opened ends are evaluated. When it is possible, three TEM grids of the same sample are examined.
For the study of CNT branching and CNT alignment along one axis, the same 10-20 photos of one TEM grid are examined and qualitatively described.
Sampling:
MW-CNTs powder (about 10mg) is poured into a vial containing a small volume of ethanol (about 30 ml). The corked vial is placed into an ultrasonic bath (frequency = 35 kHz) during five minutes at ambient temperature in order to disperse them.

Test material

Constituent 1
Chemical structure
Reference substance name:
Tangled Multi-Walled Carbon Nanotubes
EC Number:
701-160-0
Cas Number:
7782-42-5
Molecular formula:
Hollow tubular carbon, 1-dimensional nano structures with hexagonal arrangement of carbon atoms
IUPAC Name:
Tangled Multi-Walled Carbon Nanotubes
Constituent 2
Reference substance name:
GRAPHISTRENGTH C100
IUPAC Name:
GRAPHISTRENGTH C100
Test material form:
solid: nanoform

Data gathering

Instruments:
Philips - FEI CM200 microscope: LaB6 filament, maximal voltage = 200 kV, point by point resolution = 0.27 nm.

Results and discussion

Shape description
Key result
Shape:
tubular
Remarks on result:
other:
Remarks:
qualitative characterization of carbon nanotubes

Any other information on results incl. tables

Some examples of TEM images obtained at magnification of 44000x, 58000x and 78000x on the sample show that carbon nanotubes are tortuous and that they have no branching.

The proportion of opened tube ends of the tests item was about 10%.

Applicant's summary and conclusion

Conclusions:
Carbon nanotubes present a tubular shape. The proportion of opened tube ends of the tests item was about 10%. Carbon nanotubes of the test item did not seem to show branches.
Carbon nanotubes of the test item were generally long and tortuous, so there was no alignment along one axis.
This specifically apply to tested item.