IXTKKACTIO.N OF I'OL^M KHS AM) M KCHA.NK ' AL WAVKS 311 



tlirco ^Maxwell eloiiKMits in i)arall('l witli again, as in Fig. 10, a sohcnt 

 \is('()sity. this tinio calUMl tji (truly ahsolulc sohxMit x'iscosity) in pai'allcl 

 with tlicni. 'I'hc ^u/, cui'xc ot Fig. IS, running through the ol)S('r\'('(l 

 points could then be calculated, by some special ti'ial methods, with 

 which Messrs. H. T. O'Xcnl and (). J. Zol)el of Bell Telephone Labora- 

 tories kiii(ll>- helped. 



This analysis, identifying three principal relaxation regions for the 

 motions of polyisobutylene chains in cyclohexane, gave for a 1 per cent 

 solution (taken as linear part of concentration curx'e and hence e(iui\'a- 

 lent to high dilution). 



Principal rigidities H2 — 890 dynes cm" 

 fjL-.i = 3,190 dynes cm' 

 M4 = 84,000 dynes/cm" 

 Principal viscosities r?i = 0.0082 poise (pui'c cyclohexane) 

 7]2 = 0.255 poise 

 173 = 0.000 poise 

 r?4 = 0.004 poise 

 Principal relaxation frequencies j'2 = 550 cycles 



f, = 8.45 X 10' cycles 

 fi = 3.52 X 10' cycles 



Tentatively, these mechanisms may be schematically described as on 

 Fig. 19. Here, the polymer coil, subjected to shear waves hi dilute solu- 

 tion, exhibits rigidities ^2 , Ms and ^4 , all shoAvn on different scales. m2 is 

 the configurational elasticity because of actual changes in root mean 

 scjuare separation of chain ends, as from R to R'. It is retarded by vis- 

 cous drag through the solvent, 772 , which is presumably the main source 

 of characteristically high t?^ of chain polymer solutions. The relaxation 

 frecjuency for this mechanism is low — a few hundred cycles. It may 

 come in significantly in work on more concentrated solutions at low 

 frequencies,"*' "' ' "' where chain entanglement is nevertheless the dom- 

 inant factor. 



ju:! is when segments of the same chain in the molecular coil tempoi'ai-ily 

 entangle with each other. Striking evidence has recently been given liy 

 Fox and Flor}^^* that because of mutual interference, the theoretical 

 random flight configuration of a chain gives very much too small a 



