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Ultrathin Sectioning Of Polymeric Materials For Low-voltage Transmission Electron Microscopy: Relief On Ultrathin Sections

Ultrathin sectioning, one of the types of specimen preparations for transmission electron microscopy (TEM), has been considered the most perfect sectioning technique leading to the thinnest sections (50–100 nm). Following a study based on a newly developed low-voltage TEM technique, a relief on the ultrathin sections of polymer blends was observed that was ascribed to substantial differences in mechanical properties of the blend constituents.[1] In this study, an analogous relief was observed with a blend, the constituents of which are both hard in cutting. The origin of the surface relief on ultrathin sections of polymer blends was sought using low-voltage scanning TEM and atomic force microscopy. Polycarbonate/styrene-co-acrylonitrile blend was examined as a representative of blends with all components well under T g at room temperature. A distinct surface relief was observed on both ultrathin sections and remaining cut surfaces of the blend for low-temperature and room-temperature cutting. A rougher surface relief was found on the ultrathin sections than on the remaining cut surfaces. The surface relief was assumed to occur in the course of the cutting when extensive shearing occurs. Correspondence of the surface relief with the phase structure proves the influence of different mechanical behavior of individual blend components on the resulting morphology. #Presented in part at the 5th Multinational Congress on Electron Microscopy, Lecce, Italy, 20–25 September 2001.