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
Surfactant template synthesis of mesoporous silica monolith was carried out via modified fast sol gel process. It was easy to obtain crack free silica monolith due to low volume shrinkage during the gelation. The morp...Surfactant template synthesis of mesoporous silica monolith was carried out via modified fast sol gel process. It was easy to obtain crack free silica monolith due to low volume shrinkage during the gelation. The morphology of the titled silica was characterized by transmission electron microscopy and X ray diffraction. The results showed that the pores were worm like and the pore size was about 4 nm. Further nitrogen isothermal absorption experiment indicated that the specific area of the titled material was 391 m 2/g, which was comparable with the reported value 306 m 2/g in literature.展开更多
A method determining molecular weight distribution index D (MWD) from viscosity versus shear stress flow curves for polypropylene has been presented.Based on the experimental data,the correlation between the viscosity...A method determining molecular weight distribution index D (MWD) from viscosity versus shear stress flow curves for polypropylene has been presented.Based on the experimental data,the correlation between the viscosity η of molten polypropylene and its MWD can be expressed as η/η-0=｛1+a(τD)+m｝+{-1},where η-0 is the zero shear viscosity, τ is the shear stress, a and m are empirical parameters.Furthermore,a simpler method to estimate the MWD from only two experimental data,i.e.the melt index (MI) and the zero shear viscosity has also been presented,the calculated results are in good agreement with the data from GPC measurements.展开更多
Monodispersed polystyrene latexes (100～500 nm) were prepared using seed emulsion polymerization.Hard and ordered polystyrene colloidal crystals were obtained by ambient drying the monodispersed polystyrene dispersion...Monodispersed polystyrene latexes (100～500 nm) were prepared using seed emulsion polymerization.Hard and ordered polystyrene colloidal crystals were obtained by ambient drying the monodispersed polystyrene dispersions.Polystyrene colloidal crystals were chemically modified by controlled sulfonation with sulfuric acid to derive a novel macro ordered hydrogels including ordered hydrogels and core/shell hydrogels,in which sulfuric acid and sulfone groups are responsible for the hydrophilic and crosslinking performances,respectively.The chemical structure and morphologies of the hydrogels were characterized by FT IR.It is shown that at a given concentration of sulfuric acid,the structural features of the samples are controlled by sulfonation time and temperature.The modification starts from the outer layer of polystyrene spheres of the colloidal crystals and increases both in reaction rate and sulfone group amount with temperature.A preliminary mechanism of the sulfonation process to prepare the ordered structures was proposed.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
The monodisperse silica particles self-assembled colloidal crystals were used as templates to synthesize pH value and temperature responsive ordered macorporous hydrogels. The ordered structure arranged by the uniform...The monodisperse silica particles self-assembled colloidal crystals were used as templates to synthesize pH value and temperature responsive ordered macorporous hydrogels. The ordered structure arranged by the uniform pores and the pore-pore interconnectivity through the window channel is confirmed by SEM characterization. UV-Vis-near IR absorption experiment result reveals that the wavelength at the stop band peak is tunable within the whole visible spectrum via simply altering some parameters such as pH value and light incidence angle. This finding allows to design frequency-tunable photonic band gap materials.展开更多
Monodisperse core-shell (polystyrene/DAAM-EA-AM) emulsions were prepared by two-step seed polymerization,and crosslinked films were obtained by ambient drying the copolymerization emulsions accompanying a interfacial ...Monodisperse core-shell (polystyrene/DAAM-EA-AM) emulsions were prepared by two-step seed polymerization,and crosslinked films were obtained by ambient drying the copolymerization emulsions accompanying a interfacial crosslinking between DAAM/ADDH.The crosslinking degree increased with thermal treatment temperature and time.After alkaline hydrolysis of ester and amide groups resulting carboxylic groups,the films were transformed to be mesostructured hydrogels.The chemical composition and ordered morphologies were experimentally confirmed by FT-IR,SEM and POM.Water uptake of the hydrogels decreased with the thermal treatment time of the films,implying the crosslinking degree also increased.展开更多
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.
文摘Surfactant template synthesis of mesoporous silica monolith was carried out via modified fast sol gel process. It was easy to obtain crack free silica monolith due to low volume shrinkage during the gelation. The morphology of the titled silica was characterized by transmission electron microscopy and X ray diffraction. The results showed that the pores were worm like and the pore size was about 4 nm. Further nitrogen isothermal absorption experiment indicated that the specific area of the titled material was 391 m 2/g, which was comparable with the reported value 306 m 2/g in literature.
文摘A method determining molecular weight distribution index D (MWD) from viscosity versus shear stress flow curves for polypropylene has been presented.Based on the experimental data,the correlation between the viscosity η of molten polypropylene and its MWD can be expressed as η/η-0=｛1+a(τD)+m｝+{-1},where η-0 is the zero shear viscosity, τ is the shear stress, a and m are empirical parameters.Furthermore,a simpler method to estimate the MWD from only two experimental data,i.e.the melt index (MI) and the zero shear viscosity has also been presented,the calculated results are in good agreement with the data from GPC measurements.
文摘Monodispersed polystyrene latexes (100～500 nm) were prepared using seed emulsion polymerization.Hard and ordered polystyrene colloidal crystals were obtained by ambient drying the monodispersed polystyrene dispersions.Polystyrene colloidal crystals were chemically modified by controlled sulfonation with sulfuric acid to derive a novel macro ordered hydrogels including ordered hydrogels and core/shell hydrogels,in which sulfuric acid and sulfone groups are responsible for the hydrophilic and crosslinking performances,respectively.The chemical structure and morphologies of the hydrogels were characterized by FT IR.It is shown that at a given concentration of sulfuric acid,the structural features of the samples are controlled by sulfonation time and temperature.The modification starts from the outer layer of polystyrene spheres of the colloidal crystals and increases both in reaction rate and sulfone group amount with temperature.A preliminary mechanism of the sulfonation process to prepare the ordered structures was proposed.
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The monodisperse silica particles self-assembled colloidal crystals were used as templates to synthesize pH value and temperature responsive ordered macorporous hydrogels. The ordered structure arranged by the uniform pores and the pore-pore interconnectivity through the window channel is confirmed by SEM characterization. UV-Vis-near IR absorption experiment result reveals that the wavelength at the stop band peak is tunable within the whole visible spectrum via simply altering some parameters such as pH value and light incidence angle. This finding allows to design frequency-tunable photonic band gap materials.
文摘Monodisperse core-shell (polystyrene/DAAM-EA-AM) emulsions were prepared by two-step seed polymerization,and crosslinked films were obtained by ambient drying the copolymerization emulsions accompanying a interfacial crosslinking between DAAM/ADDH.The crosslinking degree increased with thermal treatment temperature and time.After alkaline hydrolysis of ester and amide groups resulting carboxylic groups,the films were transformed to be mesostructured hydrogels.The chemical composition and ordered morphologies were experimentally confirmed by FT-IR,SEM and POM.Water uptake of the hydrogels decreased with the thermal treatment time of the films,implying the crosslinking degree also increased.
