Benoit-Doty curve

The solid line in Figure 5-11 represents eq 4.1 and hereafter is referred to as the Benoit-Doty curve after the authors [50] who first derived eq 2.4. 

The PHIC data of Figure 5-3 exhibit no discernible deviation from the Benoit-Doty curve up to k = 30—50, in contrast to the prediction from the Yamakawa-Shimeida theory. Althou whether this feature is characteristic or not of very stiff pol)mers such as PHIC remains to be seen, the following remark may be in order. The computation of Yamakawa and Shimada refers to a particu- ai polymethylene-like chciin in which bead-bead interactions higher than the pentane one are treated as responsible for excluded-volume effects. Thougji it sounds reasonable, this treatment seems to require further investigation. 

From their light-scattering measurements Holtzer, Benoit, and Doty (126) concluded that the short-range interactions control the dimensions of cellulose nitrate chains, and they discussed their results in terms of the worm-like chain model of Kratky and Porod (142), obtaining a persistence length of about 34.7 A. In Fig. 21 these data are shown as a plot of (S yjMw against Mw. The open circles are the experimental points and the broken curve is that calculated from the equations for the worm-like chain model. The theoretical curve is claimed to reproduce the data to within the probable experimental error in all but two cases. 

Fig. 21. Dimensions of cellulose nitrates. Circles, data of Holtzer, Benoit and Doty (126)- Full curve, present theory for flexible chain with expansion factor dashed curve, warmlike chain without expansion factor...

---