Monodisperse core/shell latex particles composed of a polystyrene(PS) core and a thin conductive polypyrrole (PPy) shell were synthesized by means of two-stage emulsion polymerization. Proofs for the success of core/s...Monodisperse core/shell latex particles composed of a polystyrene(PS) core and a thin conductive polypyrrole (PPy) shell were synthesized by means of two-stage emulsion polymerization. Proofs for the success of core/shell synthesis were obtained by using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy(XPS). Pressed pellet conductivity measurements on the dried composites indicated a low percolation threshold of 13.8%. The conductivity for the composites was higher than that of a heterogeneous admixture of dried PS latex and PPy bulk powder. The highest conductivity of the core/shell composite was 0.14 S/cm.展开更多
基于FPGA芯片Stratix Ⅱ EP2S60F672C4设计实现了数字基带预失真系统中的环路延迟估计模块。该模块运用了一种环路延迟估计新方法,易于FPGA实现。同时,在信号失真的情况下也能给出正确的估计结果。Modelsim SE 6.5c的时序仿真结果和Sign...基于FPGA芯片Stratix Ⅱ EP2S60F672C4设计实现了数字基带预失真系统中的环路延迟估计模块。该模块运用了一种环路延迟估计新方法,易于FPGA实现。同时,在信号失真的情况下也能给出正确的估计结果。Modelsim SE 6.5c的时序仿真结果和SignalTaps Ⅱ的硬件调试结果验证了模块的有效性。展开更多
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
Monodisperse polypyrrole（PPy） composite microspheres and hollow capsules based on the monodisperse core-shell gel template particles were prepared. The core-shell gel particles were obtained by the inward sulfonatio...Monodisperse polypyrrole（PPy） composite microspheres and hollow capsules based on the monodisperse core-shell gel template particles were prepared. The core-shell gel particles were obtained by the inward sulfonation of monodisperse polystyrene particles. The shell thickness and core size were synchronously controlled in the particle radius range. After the polymerization initiated by ammonium per sulfate（APS）, PPy was formed in the sulfonated polystyrene shell. PPy hollow capsules were derived after the polystyrene cores were dissolved: their cavity size and shell thickness were synchronously controlled by using core-shell gel particles with different sulfonation extent. It is interesting that if Fe3+ was adsorbed into the sulfonated polystyrene shell as the initiator, the PPy-shell collapsed into a pile of small particles when the polystyrene core was dissolved.展开更多
文摘Monodisperse core/shell latex particles composed of a polystyrene(PS) core and a thin conductive polypyrrole (PPy) shell were synthesized by means of two-stage emulsion polymerization. Proofs for the success of core/shell synthesis were obtained by using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy(XPS). Pressed pellet conductivity measurements on the dried composites indicated a low percolation threshold of 13.8%. The conductivity for the composites was higher than that of a heterogeneous admixture of dried PS latex and PPy bulk powder. The highest conductivity of the core/shell composite was 0.14 S/cm.
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Monodisperse polypyrrole（PPy） composite microspheres and hollow capsules based on the monodisperse core-shell gel template particles were prepared. The core-shell gel particles were obtained by the inward sulfonation of monodisperse polystyrene particles. The shell thickness and core size were synchronously controlled in the particle radius range. After the polymerization initiated by ammonium per sulfate（APS）, PPy was formed in the sulfonated polystyrene shell. PPy hollow capsules were derived after the polystyrene cores were dissolved: their cavity size and shell thickness were synchronously controlled by using core-shell gel particles with different sulfonation extent. It is interesting that if Fe3+ was adsorbed into the sulfonated polystyrene shell as the initiator, the PPy-shell collapsed into a pile of small particles when the polystyrene core was dissolved.
