Cellulose acetate membrane history

The development of asymmetric membrane technology in the 1960 s was a critical point in the history of gas separations. These asymmetric structures consist of a thin (0.1 utol n) dense skin supported on a coarse open-cell foam stmcture. A mmetric membranes composed of the polyimides discussed above can provide extremely high fluxes throuj the thin dense skin, and still possess the inherently hij separation factors of the basic glassy polymers from which they are made. In the early 1960 s, Loeb and Sourirajan described techniques for producing asymmetric cellulose acetate membranes suitable for separation operations. The processes involved in membrane formation are complex. It is believed that the thin dense skin forms at the... 

Figures 8a-c show typical DSC melting endotherms for water in membranes 1-3. The shapes of the peaks, compared to that for pure water in Figure 8d, are quite complex, and give the appearance of two endothermic events near 0°C. This may be due to interaction of water with the polymer film as suggested by earlier workers who have made similar observations in hydrogels (8, ) and in cellulose acetate membranes (10). or perhaps to a change in thermal conductivity of the sample during melting (11). In any case, the shape of the endotherm does depend on the thermal history of the sample, as shown in Figure 9, while its total size remains unchanged within the precision of the experiment.

HISTORY OF CELLULOSE ACETATE MEMBRANE 2.2.1 Development of Loeb-Sourirajan Membrane... 

The last section Applied Aspects of Membrane Gas Separation contains three chapters. Brunetti et al. start their contribution with a brief review of membrane materials and membranes used in gas separation and survey the main directions of industrial applications of gas separation (hydrogen recovery, air separation, etc.). In the second part of their chapter they present a new concept for comparison of membrane and other, more traditional, methods for gas separation. Their approach includes a consideration of engineering, economical, environmental and social indicators. Something similar had been written 15 years ago [2] but this analysis is now rather outdated. White (Chapter 15) focuses on a specific but very important problem in industrial gas separation membrane separation of natural gas. The main emphasis is on cellulose acetate based membranes that have the longest history of practical applications. This chapter also contains the results of field tests of these membranes and considers approaches how to reduce the size and cost of industrial membrane systems. The final chapter is an example of detailed engineering... 

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