In this paper, we discussed the drying behavior of monodispersed polystyrene latex at high temperature with particular attention to the morphological evolution during film formation process. At the beginning of the wa...In this paper, we discussed the drying behavior of monodispersed polystyrene latex at high temperature with particular attention to the morphological evolution during film formation process. At the beginning of the water evaporation, a skin film with some defects was formed at latex/air interface, water evaporated thereby in a constant rate. During this stage, a drying front advanced from the top film towards the bulk dispersion. Afterwards, most water was lost, and water evaporation rate was less than that of the initial stage. In this case, the whole system became immobile, and another drying front developed from the interior region outside the system. Two distinct boundaries between completely dried region and wet region corresponding to the opposite directions of the second drying front were found if the film peeled from the container bottom surface. Besides, some particular morphologies were found in the completely dried region, which was likely related to preferable coalescence among the particles induced by capillary force due to water evaporation.展开更多
In the present work, oil-in-water emulsions were prepared with toluene-water as working system, sodium lauryl sulfate as emulsifier,and α-Al2O3 ceramic membrane with pore size of 1.5 μm as emulsifying medium in a ne...In the present work, oil-in-water emulsions were prepared with toluene-water as working system, sodium lauryl sulfate as emulsifier,and α-Al2O3 ceramic membrane with pore size of 1.5 μm as emulsifying medium in a new submerged emulsification apparatus. The effects of stirring speed,transmembrane pressure and emulsifier concentration on the droplet size of emulsions and its distribution as well as the dispersed phase flux were studied. The experimental results showed that monodispersed oil-in-water emulsions could be obtained with the ceramic membrane emulsification system. With the increase of stirring speed and emulsifier concentration, mean droplet size and the span of the droplet size distribution decreased, and the dispersed phase flux hardly changed at the same time.However,mean droplet size and the span of the droplet size distribution increased, and the dispersed phase flux increased significantly with the increase of transmembrane pressure. A linear relationship between the dispersed phase flux and transmembrane pressure at low pressures was obtained.展开更多
文摘In this paper, we discussed the drying behavior of monodispersed polystyrene latex at high temperature with particular attention to the morphological evolution during film formation process. At the beginning of the water evaporation, a skin film with some defects was formed at latex/air interface, water evaporated thereby in a constant rate. During this stage, a drying front advanced from the top film towards the bulk dispersion. Afterwards, most water was lost, and water evaporation rate was less than that of the initial stage. In this case, the whole system became immobile, and another drying front developed from the interior region outside the system. Two distinct boundaries between completely dried region and wet region corresponding to the opposite directions of the second drying front were found if the film peeled from the container bottom surface. Besides, some particular morphologies were found in the completely dried region, which was likely related to preferable coalescence among the particles induced by capillary force due to water evaporation.
文摘In the present work, oil-in-water emulsions were prepared with toluene-water as working system, sodium lauryl sulfate as emulsifier,and α-Al2O3 ceramic membrane with pore size of 1.5 μm as emulsifying medium in a new submerged emulsification apparatus. The effects of stirring speed,transmembrane pressure and emulsifier concentration on the droplet size of emulsions and its distribution as well as the dispersed phase flux were studied. The experimental results showed that monodispersed oil-in-water emulsions could be obtained with the ceramic membrane emulsification system. With the increase of stirring speed and emulsifier concentration, mean droplet size and the span of the droplet size distribution decreased, and the dispersed phase flux hardly changed at the same time.However,mean droplet size and the span of the droplet size distribution increased, and the dispersed phase flux increased significantly with the increase of transmembrane pressure. A linear relationship between the dispersed phase flux and transmembrane pressure at low pressures was obtained.
