A series of nonionic polyacrylamide hydrogels, using acrylamide as monomer and N,N＇-methylene diacrylamide as crosslinking agent, were prepared by the free radical polymerization in aqueous solution. Swelling equilib...A series of nonionic polyacrylamide hydrogels, using acrylamide as monomer and N,N＇-methylene diacrylamide as crosslinking agent, were prepared by the free radical polymerization in aqueous solution. Swelling equilibria for the gels were carried out in aqueous solutions of NaCl, KCI, CaCl2, Na2HPO4 and K2HPO4 with concentration ranging from 10^-3 to 5mol/kgH2O at 25 ℃. Experimental results revealed that the chlorides and phosphates cause a different behavior at higher salt concentration. The swelling ratio increases with increasing concentration of chlorides salts, while decreases with the increased phosphates salt concentration. The phenomena seem to be related to the different interactions of chloride and hydrogen phosphate ions with the network groups. Furthermore, the effects of different concentration of crosslinking agent and total monomers on gel swelling performance were also investigated.展开更多
Further development in the field of geothermal energy require reliable reference data on the thermophysical properties of geothermal waters,namely,on the thermal conductivity and viscosity of aqueous salt solutions at...Further development in the field of geothermal energy require reliable reference data on the thermophysical properties of geothermal waters,namely,on the thermal conductivity and viscosity of aqueous salt solutions at temperatures of 293–473 K,pressures Ps=100 MPa,and concentrations of 0–25 wt.%.Given the lack of data and models,especially for the dynamic viscosity of aqueous salt solutions at a pressure of above 40 MPa,generalized formulas are presented here,by which these gaps can be filled.The article presents a generalized formula for obtaining reliable data on the thermal conductivity of water aqueous solutions of salts for Ps=100 MPa,temperatures of 293–473 K and concentrations of 0%–25%(wt.%),as well as generalized formulas for the dynamic viscosity of water up to pressures of 500 MPa and aqueous solutions of salts for Ps=100 MPa,temperatures 333–473 K,and concentration 0%–25%.The obtained values agree with the experimental data within 1.6%.展开更多
基金Sci.and Tech. Ministry of Fujian (2005I010)Natural Sci. Foundation of Fujian (C0410006).
文摘A series of nonionic polyacrylamide hydrogels, using acrylamide as monomer and N,N＇-methylene diacrylamide as crosslinking agent, were prepared by the free radical polymerization in aqueous solution. Swelling equilibria for the gels were carried out in aqueous solutions of NaCl, KCI, CaCl2, Na2HPO4 and K2HPO4 with concentration ranging from 10^-3 to 5mol/kgH2O at 25 ℃. Experimental results revealed that the chlorides and phosphates cause a different behavior at higher salt concentration. The swelling ratio increases with increasing concentration of chlorides salts, while decreases with the increased phosphates salt concentration. The phenomena seem to be related to the different interactions of chloride and hydrogen phosphate ions with the network groups. Furthermore, the effects of different concentration of crosslinking agent and total monomers on gel swelling performance were also investigated.
文摘Further development in the field of geothermal energy require reliable reference data on the thermophysical properties of geothermal waters,namely,on the thermal conductivity and viscosity of aqueous salt solutions at temperatures of 293–473 K,pressures Ps=100 MPa,and concentrations of 0–25 wt.%.Given the lack of data and models,especially for the dynamic viscosity of aqueous salt solutions at a pressure of above 40 MPa,generalized formulas are presented here,by which these gaps can be filled.The article presents a generalized formula for obtaining reliable data on the thermal conductivity of water aqueous solutions of salts for Ps=100 MPa,temperatures of 293–473 K and concentrations of 0%–25%(wt.%),as well as generalized formulas for the dynamic viscosity of water up to pressures of 500 MPa and aqueous solutions of salts for Ps=100 MPa,temperatures 333–473 K,and concentration 0%–25%.The obtained values agree with the experimental data within 1.6%.
