Io6 FUNDAMENTALS OF S U B.M I C RO S COPI C MORPHOLOGY I 



consists of Debye-Scherrer rings. If the orientation of the micellar 

 strands is completely random, photometric measurements show the 

 intensity round each ring to be constant. If, now, the isotropic fibres 

 are stretched, the micellar strands are oriented. With increasing stretch, 

 the X-ray diagram changes into a sickle diagram and finally into a fibre 

 diagram (Fig. 67, p. 97) when orientation is complete. If, at a given 



(1 ) 



hO 1.25 1.62 



f» .| 



1.89 



Fig. 75. X-ray diagram of Hermans's threads, gradually stretched. The numbers give the 

 degree of stretching (length of stretched gel/original length). (From Kratky, 1940). 



degree of stretch, one measures the intensity along the interference 

 sickles corresponding to the equator interferences in the fibre diagram 

 (paratropic interferences), the/r^^//^;z(7 with which the different orienta- 

 tions of the micellar strands occur can be derived from the decline in 

 intensity from the equator towards the poles. In fact, the intensity 

 depends on the number of lattice planes which take part in the reflexion 

 of X-rays. It is possible in this way to determine experimentally the 

 distribution function of the orientations of micellar axes. 



