Electron Microscopy of Cellulose Acetate Reverse-Osmotic Membranes by Means of the Improved Replication Method
1981; American Chemical Society; Linguagem: Inglês
10.1021/bk-1981-0153.ch017
ISSN1947-5918
Autores Tópico(s)Enhanced Oil Recovery Techniques
ResumoThe diameters of the pores of the surface layer of Loeb-Sourirajan-type cellulose acetate membranes have been reported by several authors (1-6). The reported values of the diameters cover the range between 10 Å and 60 Å. For electron microscopic observations, the replication method must be used. In order to obtain the excellently contrasted images the surface of the sample is shadowed with heavy metals in vacuum. In many cases the Pt-Pd alloy has been used as a pre-shadowing metal. But the resolution of the Pt-Pd replica is at the level of about 50 Å, since the size of the evaporated particles is between 20 Å and 40 Å (7, 8, 9). If the pore sizes are in the range of the abovementioned level, we cannot observe them. By means of the more advanced replication technique using tungsten as a pre-shadowing metal, the electron microscopic observation of both the pores and
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