LIU Dawei;YANG Minhui;DU Huashan
Chemical sensitization is a widely applied, convenient and rapid method in foaming the emulsion matrix. However, compared with physical way, chemical method is more complicated, which were rarely researched systematically. In this study, the relation of various involving factors, which include the amount of NaNO2, pH value, different types of acid, catalysts and temperature, and the emulsion foaming process, were investigated. The following were the findings: the foaming process was accelerated obviously by increasing the concentration of NaNO2 and temperature in matrix to improve the activity of NaNO2 ; a higher rate of foaming was attained if lowering the pH value of matrix, via applying stronger acid or increasing the concentration of weak acid; low temperature sensitization was achieved through introducing M2+ as a positive catalyst; when the concentration of M2+ reached 35% mass fraction in the sensitizer, a fastest rate was achieved;higher foaming rate resulted in more NO x production and the matrix presented yellow color especially under a lower pH of the matrix; too low pH in the dispersed phase leads to a poor quality of emulsion; since big useless bubbles were easily formed under a high rate of foaming, for an optimum sensitizing result, the rate should be controlled.