✍ Scribed by D. J. Massa
No coin nor oath required. For personal study only.
Viscosity η, recoil Γ, and longest retardation time τ~1R~ were measured for buffered aqueous solution of T2 DNA (M = 1.3 × 10^8^) and cell lysattes of __Bacillus subtiles W__23 (DNA M = 2 × 10^9^) as a function of concetration, shear stress σ, and time of shear t, using a cartesian‐diver‐suspended couette flow system. For the T2 solution, η decreased with increasing σ, Γ(t) going through a maximum with t. For the B. subtiles lysates, the preponderant rheological component of which is chromatin DNA, above a critical σ, the η, Γ(t), and τ~1R~ increased t over 15 to 45 minutes duration to values up to several times larger, indicating the formation of intermolecular aggregates. The onset of such effects and their significance in th e measurement of molecular properties by hydrodynamic means is disscussed.
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The behaviour of ultra-high molecular weight poly(butyl methacrylate) (/~w = 9.59 × 106-24.50 × 106) in dilute solution in methyl ethyl ketone, benzene, dioxane, and cyclohexanone, at 25c'C. has been investigated by viscometry. Mark Houwink relations have been established, and the unperturbed dimens