Semidilute regime, definition

One arbitrary definition of the semidilute regime is the concentration range c [Pg.78]

The semidilute regime is often specified by c c< c. With c at around 10 g/L for polystyrene of = 6 X 10 g/mol, for instance, and c at around 300 g/L, the double inequality may appear to impose a severe restriction on the accessibility by an ordinary polymer. In practice, however, solutions several times as concentrated as c already qualify as semidilute solutions. With ambiguity in the definition of c (Eqs. 1.108-1.110), it does not make sense to ask how high the concentration should be for the solution to be semidilute. As we will see in many experimental results, there is an easy way to find whether or not the concentration is sufficiently high. 

There are four to six concentration regimes (Dautzenberg et al., 1994). Edwards (1966) classified them into three broad types on the basis of the number of polymer chains present, the number and length of the monomer constituting them, and the volume of the monomer relative to the volume Vt. At use levels as low as parts per thousand in food, no one definition of dilute, semidilute, or concentrated encompasses the range of weight-volume or volume-volume concentrations necessary to elicit a par-... 

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