Tubular casting equipment

Figure 1.3 Schematic on tubular casting equipment used by Loeb. Courtesy of Julius Glater, UCLA.

A decade after Dr. Hassler s efforts, Sidney Loeb and Srinivasa Sourirajan at UCLA attempted an approach to osmosis and reverse osmosis that differed from that of Dr. Hassler. Iheir approach consisted of pressurizing a solution directly against a flat, plastic film. Their work led to the development of the first asymmetric cellulose acetate membrane in 1960 (see Chapter 4.2.1). This membrane made RO a commercial viability due to the significantly improved flux, which was 10 times that of other known membrane materials at the time (such as Reid and Breton s membranes). These membranes were first cast by hand as flat sheets. Continued development in this area led to casting of tubular membranes. Figure 1.3 is a schematic of the tubular casting equipment used by Loeb and Sourirajan. Figure 1.4 shows the capped, in-floor immersion well that was used by Loeb and students and is still located in Boelter Hall at UCLA. 

Coextruded films are produced by a tubular-blown film process and a flat-die, chill-roll casting process. Capital and operating costs for blown-film vs cast-film coextrusion lines are strongly dependent on product mix and utilization. Equipment suppliers provide comparative economic evaluations for specific products. Practical cast-film equipment has been discussed previously (3). Coextrusion dies are unique. Extruders used before the die and take-away equipment used afterwards are standard equipment for single-layer film manufacture of blown or cast film (see Extrusion). 

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