14 



C. L. SADRON 



Fig. 5. c/K as a function of sin 2 6/2 in the case of a mixture of Gaussian coils. 



values of N but the same value of b 

 result of the calculation is: 



(then N is proportional to M) the 



VA7e-o Mrl 



«-JT |1 + Wr 



18 



(29) 



where N s is the z average of N. 



3. It is evident that for a mixture of particles of uniform type, but of 

 different dimensions, the asymptote of (c/K) for large values of hL will 

 be of the same form as for a monodispersed solution of particles of the same 

 type. 



For instance, in the case of Gaussian coils, 



©--iC 1 **^] 



(30) 



where N„ is the number average value of N. 



From Eqs. (29) and (30) one may draw the graph in Fig. 5, which illus- 

 trates all the conclusions that one can obtain from the complete knowledge 

 of the light-scattering curve. Other calculations of the same kind have been 

 made for mixtures of rods or mixtures of discs. 8, 9 For instance, for a mix- 

 ture of rods of different length L and the same specific weight M/L, one 

 obtains 



2 



(A 



7tW h 



7T\M/ 



+ " "^ 



(31) 



7 H. Benoit, J. Polymer. Set. 11, 507 (1953). 



s A. Holtzer, J. Polymer. Sci. 17, 432 (1955). 



a O. Kratky and G. Porod, J. Coll. Sci. 4, 35 (1949). 



