The viscosity and streaming birefringence of fractionated and unfractionated samples of sodium alginate have been measured at various concentrations, and rates of shear, and in the presence and absence of added salt. The viscosity data show the concave upward curve typical of polyelectrolytes at low concentrations, but pass through a minimum at higher concentrations. The influence of shear is least at this minimum. The initial slope of the orientation angle versus velocity gradient curves increases with concentration, but Δn/c is independent of concentration. The semiempirical theory of Peterlin for concentrated solutions is obeyed by the data for Δn, but not by that for the orientation angle. Molecular weights have been calculated from the hydrodynamic parameters. The viscosity behavior is interpreted in terms of the rigidity of the molecule.
The nitrosation of nylon 66, with the use of four different nitrosating agents, has been investigated. By the more vigorous nitrosating reactions, heterogeneous nitrosation of nylon yarn occurs rapidly and proceeds to completion in a few hours. In this reaction the amide hydrogen is substituted by a nitroso group to give the structure
By heating the nitrosated polyamides, nitrogen is evolved, and polyesters are formed. The kinetics of this change have been fully investigated. Caustic alkali reacts rapidly with nitrosated nylon. Free radicals are produced on exposure of the nitrosated nylon to visible radiation. Partial nitrosation of nylon yarns has been carried out with the use of a running threadline system; the physical properties of the resulting yarns have been examined.
The viscosity, streaming birefringence, and sedimentation of a sample of poly‐4‐vinyl‐N‐n‐butylpyridinium bromide have been measured in aqueous and in sodium chloride solutions. The theory of Peterlin for concentrated solutions has been found to be in agreement with the results. Values of the molecular weight have been calculated by different methods and a value of 9 × 105 has been chosen.
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