Voltage contrast imaging of carbon nanotube filler in rubber

Carbon nanotube (CNT) has been used as rubber fillers recently in addition to conventionally used carbon black and

silica particles. The distribution of CNT in rubber is important because it affects the properties of the rubber. The small difference in average atomic number between the CNT and the rubber makes distinction of them difficult with enough difference in material contrast by BSE signal. On the other hand, voltage contrast (VC) by SE signal enables to distinguish them by the difference of surface potential changing their SE signal intensities. Fig. 1 shows an SE image (a) of the rubber taken at 0.3 kV and a BSE image (b) of the same area taken at 3 kV. CNT could be clearly observed as bright lines in the SE image (arrow heads in Fig. 1(a)). While in the BSE image, CNT was invisible; only silica particles were observed brightly (arrows in Fig 1(b)).

Figure 1. Voltage contrast image (a) and material contrast image (b) of rubber containing carbon nanotube filler


Instrument: SU7000 FE-SEM Accelerating voltage : (a) 0.3 kV, (b) 3 kV

Magnification: 30 kx Detector (signal) : (a) Upper detector (SE), (b) Middle detector (BSE)

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