The diffusion and sedimentation of poly-p-benzamide in sulphuric acid and dimethyl acetamide

Abstract

The diffusion, intrinsic viscosity and sedimentation of 11 poly-p-benzamide (PBA) samples have been studied in 96% H2SO4 and in DMA containing 3% LiCl. The differences between the intrinsic viscosities and the diffusion coefficients of PBA in these solvents are due to the insolubility of the polymer in DMA. The rapid sedimentation method was not usable. It was found the diffusion coefficients were very dependent on the molecular weight, but the length of the Kuhn statistical segment and the hydrodynamic cross-section of the rigid molecular chains, such as those of PBA, were little affected. These conditions can be used to determine molecular weights from diffusion coefficients in H2SO4. It is also possible to calculate these from the diffusion coefficients and the intrinsic viscosities in H2SO4 by using the hydrodynamic parameter A0=3·78×10−10 erg/°C.