Integrally skinned asymmetric gas separation membranes of polyethersulfone(PES)/polyurethane(PU) blend were prepared using supercritical CO_2(SC-CO_2) as a nonsolvent for the polymer solution. The membrane consisted o...Integrally skinned asymmetric gas separation membranes of polyethersulfone(PES)/polyurethane(PU) blend were prepared using supercritical CO_2(SC-CO_2) as a nonsolvent for the polymer solution. The membrane consisted of a dense and a porous layer, which were conjoined to separate CO_2 from CH_4. The FTIR, DSC, tensile and SEM tests were performed to study and characterize the membranes. The results revealed that an increase in SC-CO_2 temperature causes an increment in permeance and a decrease in membrane selectivity. Furthermore,by raising the pressure, both permeance and selectivity increased. The modified membrane with SC-CO_2 had much higher selectivity, about 5.5 times superior to the non-modified membrane. This higher selectivity performance compared to previous works was obtained by taking the advantages of both using partial miscible blend polymer due to the strong polar–polar interaction between PU PES and SC-CO_2 to fabricate the membrane. The response surface methodology(RSM) was applied to find the relationships between several explanatory variables and CO_2 and CH_4 permeance and CO_2/CH_4 selectivity as responses. Finally, the results were validated with the experimental data, which the model results were in good agreement with the available experimental data.展开更多
Micro/nanocapsules of urea-formaldehyde resin loaded with linseed oil, which are a self-healing agent in glass flake epoxy anti-corrosion paint, were prepared using a combination of ultrasonic homogenization and in-si...Micro/nanocapsules of urea-formaldehyde resin loaded with linseed oil, which are a self-healing agent in glass flake epoxy anti-corrosion paint, were prepared using a combination of ultrasonic homogenization and in-situ polymerization. The main objective of this study was to model and optimize the microen- capsulation process. Five-level central composite design was used to design, model, and optimize the microencapsulation process. A quadratic model was constructed to show the dependency of the per- centage of encapsulated linseed oil and capsule size, as model responses, on the studied independent variables （the rotational speed of the agitator and the power and duration of sonication）. Analysis of vari- ance showed that all of the variables have significant effects on the encapsulated linseed oil percentage, while the rotational speed of the agitator and sonication time is effective variables for controlling the capsule size. Under the determined optimum conditions, a maximum encapsulated linseed oil percentage （ELO%） of 93.9% and a minimum micro/nanocapsule size of 0.574 μm were achieved at 594 rpm agitation, 350 W sonication power, and 3 min sonication time. Validation of the model was performed. The percent- age relative errors between the predicted and experimental values of the ELO% and micro/nanocapsule size are 1.28% and 3.66%, respectively. The efficacy of the optimum micro/nanocapsules in healing cracks in a glass flake epoxy paint and corrosion protection was investigated by the salt spray test and Tafel polarization technique.展开更多
文摘Integrally skinned asymmetric gas separation membranes of polyethersulfone(PES)/polyurethane(PU) blend were prepared using supercritical CO_2(SC-CO_2) as a nonsolvent for the polymer solution. The membrane consisted of a dense and a porous layer, which were conjoined to separate CO_2 from CH_4. The FTIR, DSC, tensile and SEM tests were performed to study and characterize the membranes. The results revealed that an increase in SC-CO_2 temperature causes an increment in permeance and a decrease in membrane selectivity. Furthermore,by raising the pressure, both permeance and selectivity increased. The modified membrane with SC-CO_2 had much higher selectivity, about 5.5 times superior to the non-modified membrane. This higher selectivity performance compared to previous works was obtained by taking the advantages of both using partial miscible blend polymer due to the strong polar–polar interaction between PU PES and SC-CO_2 to fabricate the membrane. The response surface methodology(RSM) was applied to find the relationships between several explanatory variables and CO_2 and CH_4 permeance and CO_2/CH_4 selectivity as responses. Finally, the results were validated with the experimental data, which the model results were in good agreement with the available experimental data.
文摘Micro/nanocapsules of urea-formaldehyde resin loaded with linseed oil, which are a self-healing agent in glass flake epoxy anti-corrosion paint, were prepared using a combination of ultrasonic homogenization and in-situ polymerization. The main objective of this study was to model and optimize the microen- capsulation process. Five-level central composite design was used to design, model, and optimize the microencapsulation process. A quadratic model was constructed to show the dependency of the per- centage of encapsulated linseed oil and capsule size, as model responses, on the studied independent variables （the rotational speed of the agitator and the power and duration of sonication）. Analysis of vari- ance showed that all of the variables have significant effects on the encapsulated linseed oil percentage, while the rotational speed of the agitator and sonication time is effective variables for controlling the capsule size. Under the determined optimum conditions, a maximum encapsulated linseed oil percentage （ELO%） of 93.9% and a minimum micro/nanocapsule size of 0.574 μm were achieved at 594 rpm agitation, 350 W sonication power, and 3 min sonication time. Validation of the model was performed. The percent- age relative errors between the predicted and experimental values of the ELO% and micro/nanocapsule size are 1.28% and 3.66%, respectively. The efficacy of the optimum micro/nanocapsules in healing cracks in a glass flake epoxy paint and corrosion protection was investigated by the salt spray test and Tafel polarization technique.
