Analyzing the quality of carbon nanotube dispersions in polymers using scanning electron microscopy

The ability to examine conducting filler particles in an insulating polymer matrix by scanning electron microscopy (SEM) was investigated. The detection of selected secondary electrons is necessary to resolve sub-micron scale filler particles, but not every SEM detector seems to be able to monitor the small changes introduced by the conducting filler particles. The influence of SEM parameters and the challenge of image interpretation in view of the apparent lack of appropriate information in literature are discussed. In accordance with other experiments on light element samples, all monitored electrons seem to be emitted within approximately 50 nm of the sample depth and no information is accessible from deeper regions even by increasing the acceleration voltage.