The effects of emulsifier molecular architecture on phase inversion process including the critical water content at phase inversion point as well as the particle size are investigated. It is found that the water conte...The effects of emulsifier molecular architecture on phase inversion process including the critical water content at phase inversion point as well as the particle size are investigated. It is found that the water content at phase inversion point reaches a maximum when the molar ratio of the hydrophilic component PEG10000 to the hydrophobic component bisphenol A epoxy resin E20 is equal to 1∶1, meanwhile, the particle size reaches a minimum (about 100 nm). From the experimental results, it can be seen that to alter the molecular architecture of the emulsifier is an effective method to control the size of the waterborne particles prepared by phase inversion emulsification technique.展开更多
Phase inversion emulsification technique is an effective physical method to prepare waterborne dispersions of polymeric resins. In this study, a multi\|hollow epoxy resin sphere was obtained by incomplete phase invers...Phase inversion emulsification technique is an effective physical method to prepare waterborne dispersions of polymeric resins. In this study, a multi\|hollow epoxy resin sphere was obtained by incomplete phase inversion emulsification. The dynamic morphological evolution of water droplets dispersed in bisphenol. A epoxy resin/emulsifier (a multi\|block copolymer) during phase inversion process was investigated with scanning electron microscopy. It is shown that small discrete water droplets are dispersed in the epoxy resin continuous phase at low water content. In this case, the dynamic coalescence among the small water droplets is ignored. With increasing water content, the dynamic coalescence becomes remarkable and larger water drops are formed by the coalescence among the small water droplets. The larger water drops are randomly distributed within the continuous phase. Meanwhile, some necklace like structures with varied length co\|exist with the small water droplets and larger water drops. Incomplete phase inversion is achieved through the coalescence among the larger water drops, and some small water droplets are entrapped therein. In this case, a kind of multi\|hollow sphere is obtained. While, in some local regions, all the nearest small water droplets coalesce simultaneously to be continuous phase to achieve complete phase inversion, and small discrete waterborne particles are obtained. The dynamic coalescence among the small water droplets dispersed in epoxy resin continuous phase could be analyzed in terms of the improved Smoluchowski equation.展开更多
This work provides a new method to prepare crosslinkable multi\|hollow micro\|spheres of epoxy resin dispersible in water by incomplete phase inversion emulsification in the presence of a catalytic curing agent.The ke...This work provides a new method to prepare crosslinkable multi\|hollow micro\|spheres of epoxy resin dispersible in water by incomplete phase inversion emulsification in the presence of a catalytic curing agent.The key is to add the curing agent in the vicinity of the phase inversion point at low temperature so as to control the emulsifier capability of the pre\|curing oligomers at a low level,which ensures the achievement of incomplete phase inversion emulsification.Scanning electron micrographs of the spheres reveal that the particles size is mainly in the range of 1~10 μm with sub\|micron cavities within the spheres.DSC is used to measure the curing behavior of the spheres.Two broad exothermic peaks around 120 and 162℃ are found in the as\|prepared particles,while the first peak shifts to higher temperature 135℃ and the onset temperature exceeds 100℃ in the thermally treated sample at 95℃ for 1 5?h.This indicates that the initial step curing process under the post\|treatment conditions is nearly completed.After further treated at high temperature for example 200℃,a glass transition temperature about 130℃ is found,and the two peaks disappear due to a full achievement of the curing process.Extraction results show that after treated at 95℃ for 1 5?h in water,the micro\|sized spheres become insoluble.It is concluded that the entitled waterborne microspheres are crosslinkable and multiporous.A preliminary result demonstrates a potential application of the entitled multi\|hollow spheres as opacifiers due to their intensive light scattering within the hollows.展开更多
Based on the insight into the mechanism of phase inversion emulsification in the presence of curing agents, a new method called surfactant free phase inversion emulsification was proposed to prepare epoxy resin waterb...Based on the insight into the mechanism of phase inversion emulsification in the presence of curing agents, a new method called surfactant free phase inversion emulsification was proposed to prepare epoxy resin waterborne dispersions. The waterborne particles are in sub micron range with narrow size distribution. Transparent cured films could be formed from the dispersions even at ambient temperature. The stability of the dispersions could be enhanced by post polymerization at a high temperature for some time. The knowledge about the phase inversion and the stability of the waterborne dispersions might provide a new way to enhance oil recovery.展开更多
文摘The effects of emulsifier molecular architecture on phase inversion process including the critical water content at phase inversion point as well as the particle size are investigated. It is found that the water content at phase inversion point reaches a maximum when the molar ratio of the hydrophilic component PEG10000 to the hydrophobic component bisphenol A epoxy resin E20 is equal to 1∶1, meanwhile, the particle size reaches a minimum (about 100 nm). From the experimental results, it can be seen that to alter the molecular architecture of the emulsifier is an effective method to control the size of the waterborne particles prepared by phase inversion emulsification technique.
文摘Phase inversion emulsification technique is an effective physical method to prepare waterborne dispersions of polymeric resins. In this study, a multi\|hollow epoxy resin sphere was obtained by incomplete phase inversion emulsification. The dynamic morphological evolution of water droplets dispersed in bisphenol. A epoxy resin/emulsifier (a multi\|block copolymer) during phase inversion process was investigated with scanning electron microscopy. It is shown that small discrete water droplets are dispersed in the epoxy resin continuous phase at low water content. In this case, the dynamic coalescence among the small water droplets is ignored. With increasing water content, the dynamic coalescence becomes remarkable and larger water drops are formed by the coalescence among the small water droplets. The larger water drops are randomly distributed within the continuous phase. Meanwhile, some necklace like structures with varied length co\|exist with the small water droplets and larger water drops. Incomplete phase inversion is achieved through the coalescence among the larger water drops, and some small water droplets are entrapped therein. In this case, a kind of multi\|hollow sphere is obtained. While, in some local regions, all the nearest small water droplets coalesce simultaneously to be continuous phase to achieve complete phase inversion, and small discrete waterborne particles are obtained. The dynamic coalescence among the small water droplets dispersed in epoxy resin continuous phase could be analyzed in terms of the improved Smoluchowski equation.
文摘This work provides a new method to prepare crosslinkable multi\|hollow micro\|spheres of epoxy resin dispersible in water by incomplete phase inversion emulsification in the presence of a catalytic curing agent.The key is to add the curing agent in the vicinity of the phase inversion point at low temperature so as to control the emulsifier capability of the pre\|curing oligomers at a low level,which ensures the achievement of incomplete phase inversion emulsification.Scanning electron micrographs of the spheres reveal that the particles size is mainly in the range of 1~10 μm with sub\|micron cavities within the spheres.DSC is used to measure the curing behavior of the spheres.Two broad exothermic peaks around 120 and 162℃ are found in the as\|prepared particles,while the first peak shifts to higher temperature 135℃ and the onset temperature exceeds 100℃ in the thermally treated sample at 95℃ for 1 5?h.This indicates that the initial step curing process under the post\|treatment conditions is nearly completed.After further treated at high temperature for example 200℃,a glass transition temperature about 130℃ is found,and the two peaks disappear due to a full achievement of the curing process.Extraction results show that after treated at 95℃ for 1 5?h in water,the micro\|sized spheres become insoluble.It is concluded that the entitled waterborne microspheres are crosslinkable and multiporous.A preliminary result demonstrates a potential application of the entitled multi\|hollow spheres as opacifiers due to their intensive light scattering within the hollows.
文摘Based on the insight into the mechanism of phase inversion emulsification in the presence of curing agents, a new method called surfactant free phase inversion emulsification was proposed to prepare epoxy resin waterborne dispersions. The waterborne particles are in sub micron range with narrow size distribution. Transparent cured films could be formed from the dispersions even at ambient temperature. The stability of the dispersions could be enhanced by post polymerization at a high temperature for some time. The knowledge about the phase inversion and the stability of the waterborne dispersions might provide a new way to enhance oil recovery.