Rigid backbone polymers

Summary It is shown that the inverse velocity of a fallingball in, or _m the apparent minimum viscosity of, anisotropic solutions of poly(n-hexylisocyanate) in toluene, are molecular weight dependent. The molecular weight dependence follows two linear branches. Below M_w=42600 the apparent minimum viscosity is very weakly dependent on M_w. Above M_w=42600 the apparent minimum viscosity of the anisotropic solution is strongly dependent on the molecular weight.