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
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.
