Aqueous solution properties of dendrimer PPI[Poly(propylene imine)] were studied by measuring viscosity parameters. Particularly on the extremely dilute concentration region were focused on. The adsorption constant k ...Aqueous solution properties of dendrimer PPI[Poly(propylene imine)] were studied by measuring viscosity parameters. Particularly on the extremely dilute concentration region were focused on. The adsorption constant k , critical concentration c a, intrinsic viscosity[ η ], intermolecular association constant K m and hydrodynamic contact concentration c s were calculated. And the generation number dependence of these parameters were also studied. From the results, the unique behavior of dendrimer solution was explained preliminary. The adsorption phenomenon of polymer solution is general, and the adsorption theory is also fit for dendrimers. Furthermore, the dynamic contact concentration c s was determined by a simple viscosity method for the first time.展开更多
A novel type of polyurethane and polyether-polyimide blends were prepared in two steps. The first step was the preparation of polyether-amic acid by the reaction of an oligmer based on polytetramethylene oxide glycol ...A novel type of polyurethane and polyether-polyimide blends were prepared in two steps. The first step was the preparation of polyether-amic acid by the reaction of an oligmer based on polytetramethylene oxide glycol di-p-aminobenzoate (APTMO) of different molecular weight with benzenetetracarboxylic acid dianhydride (PMDA). The second step was mixing polyether-polyurethane and polyether-polyamic acid solution at room tem- perature in various weight ratios and the blend films were obtained by casting and then heating imidization .In- frared spectroscopy, dynamic mechanical analysis,differential scanning calorimetry,, wide-angle X-ray diffraction and sham-sires testing were used to study this family of blends. DMA and DSC results show that the blends exhibit a well phase-separated morphology and possess a wide range of service temperature, which varies with the PU content. The thermal stability of PU is found to increase obviously by the incorporation of PI. The excellent tensile properties of the blends suggest that they could be potentially ed as heat resistant thermoplastic elas-tomers.展开更多
文摘Aqueous solution properties of dendrimer PPI[Poly(propylene imine)] were studied by measuring viscosity parameters. Particularly on the extremely dilute concentration region were focused on. The adsorption constant k , critical concentration c a, intrinsic viscosity[ η ], intermolecular association constant K m and hydrodynamic contact concentration c s were calculated. And the generation number dependence of these parameters were also studied. From the results, the unique behavior of dendrimer solution was explained preliminary. The adsorption phenomenon of polymer solution is general, and the adsorption theory is also fit for dendrimers. Furthermore, the dynamic contact concentration c s was determined by a simple viscosity method for the first time.
文摘A novel type of polyurethane and polyether-polyimide blends were prepared in two steps. The first step was the preparation of polyether-amic acid by the reaction of an oligmer based on polytetramethylene oxide glycol di-p-aminobenzoate (APTMO) of different molecular weight with benzenetetracarboxylic acid dianhydride (PMDA). The second step was mixing polyether-polyurethane and polyether-polyamic acid solution at room tem- perature in various weight ratios and the blend films were obtained by casting and then heating imidization .In- frared spectroscopy, dynamic mechanical analysis,differential scanning calorimetry,, wide-angle X-ray diffraction and sham-sires testing were used to study this family of blends. DMA and DSC results show that the blends exhibit a well phase-separated morphology and possess a wide range of service temperature, which varies with the PU content. The thermal stability of PU is found to increase obviously by the incorporation of PI. The excellent tensile properties of the blends suggest that they could be potentially ed as heat resistant thermoplastic elas-tomers.
