RESUMO
The intrinsic viscosity of polyarylates having different molecular weights was calculated in O-chlorophenol at 30C. The root-mean-square distance [h 2] 1/2 separating the ends of polyarylates chain was calculated. Analysis of data indicated that the intrinsic viscosity is proportional to the average molecular weight and [h 2] 1/2. The slopes of Stock-Mayer and Fixman plots were used to determine the mutual excluded volume [beta] of segments. The beta-values obtained were compared with the values calculated for the poly[nitroarylates] and were found to be in the order: Beta poly[nitroarylates] > > beta[polyarylates]. This was due to the presence of the nitro group and the ether linkage in the backbone of the polyarylates
Assuntos
Viscosidade , Poliésteres/químicaRESUMO
Fluorescence measurements were carried out for a very widely-used probe 8-anilino- 1-naphthalenesulphonic acid in different hydrazine-water mixtures. The concentration of 8-anilino-1-naphthalenesulphonic acid in various hydrazine compositions is about 9, 3x15[-5] mol/1. The measurements were carried out at excited wave length [379 nm]. In all the range of hydrazine-water mixtures, a maximum intensity was located at XN[2]H[4]-0.25. This phenomenon is attributed to the presence of the N-aryl group in 8-anilino-1-naphthalenesulphonic acid which has electron-donating property to give photonization in water rich region. A 1:1 complex is formed between 1-aminonaphthalene portion and hydrazine through hydrogen bonding interaction. This formation caused solvent emission shift
Assuntos
Fluorescência/métodos , HidrazinasRESUMO
The rate of copper [II] zinc cementation reaction in the absence and in the presence of surface active substance was measured using atomic absorption spectrophotometer. The rate of cementation decreased with increasing copper sulfate concentration. The decrease in the rate of cementation followed the following order: C.P.Br > Triton X-100 > S.L.S