Dispersion Principle Of In-Situ Bubble Stretching And Preparation Of Magnesium-Nanocomposites With Flame Retardancy And Smoke Suppression

The physical properties and functional performances of polymer material can be improved by composing nano-powder and polymer, especially in the case of nano-powder having some especial structure and physical properties. However, the nano-powder is of small size, large specific surface area and high surface energy being extremely unsteady. The nano-powder easily loses its special performance if the powder gathering into particles of hundreds of nanometer or even several micrometer due to effects of heat and force and so on when being blended with polymer. Therefore, dispersing aggregated nano-particles in polymer melts is the key to obtain the excellent performance in the course of manufacturing process. In-situ Bubble Stretching (ISBS) is a new method for dispersing aggregated nano-particles in polymer melt by rapid stretching action in the fast expansion of bubbles in recent years. The strong stretching field can be formed by using the pressure energy of physical inflating agent or chemical energy released by decomposing chemical inflating agent when heated, which can not be obtained by conventional mechanical dispersion method.The stretching field in bubble expansion has been studied in theory by using fundamental equations on the basis of theoretical studies on expansion of bubbles. In experiments, our results showed that the main factors affect the stretching rate are original pressure and radius of the bubbles. The simulation of the distribution of stretching field in polymer field indicates that ISBS method has fine effect on dispersing aggregated nano-particles both on the surface and between the bubbles. Under the certain conditions, by controlling the different original pressure and radius of bubbles, in the range of several tens of μm from the distance of the bubble surface, the dispersion...