Intrinsic viscosities [t/] of bisphenol A polycarbonate in dichloromethane, tetrahydrofuran and a mixture of 1,1,2,2-tetrachloroethane and toluene (78.5 wt% toluene), all at 25°C, have been determined for 13 fractions ranging in weight-average molecular weight M w from 2.3 ? 103 to 2 ? 105. To estimate ((S2)o/M)o~ (the ratio of the unperturbed mean-square radius of gyration to the molecular weight M at infinite M) of the polymer, the [t/] data were analysed on the basis of the theory of Yoshizaki et al. for unperturbed touched-bead, worm-like chains but, in actuality, with the Bushin-Bohdaneck:;, method applied. It is shown that the slope of a plot of (M2/[q]) 1/3 versus M 1/2 at low Mw, where excluded-volume effects on [r/] are negligible, gives ((S2)o/M)o~ directly to a good approximation. The estimated ((S2)o/MLo values for the polycarbonate in the three solvents are all (2.2_+0.2)x 10-3nm 2, and are in good agreement with the literature data from small-angle neutron scattering in the bulk state. Excluded-volume effects on [q] in the tetrachloroethane toluene mixture are significant only for Mw above 10 5, while those in dichloromethane and tetrahydrofuran are appreciable for Mw above 5 ? 10 3 to around 10 4, or above 5 10 in terms of the Kuhn segment number.
Посилання на статтю:
On the unperturbed dimensions of bisphenol A polycarbonate / Nobuhiko Maeda and Takashi Norisuye // Polymer. – 1993. – Vol 34. – P. 3475-3480.