Studies On The Selection Of Chlorfluazuron Sc Wetting Dispersant And Mechanism Of Stability

Pesticide suspension concentrate for the multiphase coarse dispersed system, thermodynamic stability and kinetic stability were poor, as a proplem to the development of pesticide suspension concentrate. The thermodynamic stability of pesticides SC affected by the additive of wetting dispersant, study of the function principle of wetting dispersant in pesticide suspension concentrate is important for wetting dispersant additive and solution development and selection of the thermodynamic stability of the pesticide suspension concentrate. Dispersant of chlorfluazuron SC was selected,then the stability of chlorfluazuron SC effect with pH value, salt ions and other factors were studied,and the stabilization mechanism of hlorfluazuron SC were analyzed and discussed in this paper. The main research contents of this paper are as follows:1 Based on flow point method, dispersant of 10% chlorfluazuron SC were selected by laser particle size instrument.The results showed that chlorfluazuron SC added with 602, dispersing agent NNO and MOTAS had good flowability, the experiment were conducted by orthogonal test and viscosity measurement to select the proper dispersant and their dogase: 602 and MOTAS was 4:1, the dogase: was 0.8%.2 By Zeta potential measurement and rheological test, the influences of pH value and salt ions on the stability of chlorfluazuron SC were studied. The The results showed that :(1)The Zeta potential of suspension in the range of experimental pH values are negative,with the increase of the pH value, the absolute value of the Zeta potential first increases and then decreases slightly, and in the vicinity of PH 8.5 the maximum absolute value. The dissociation of ionic polymer dispersant in water affected by pH values, the stability of ionic dispersion affected by the dissociation of polymer dispersions in SC. (2)The addition of salt ions can influence the Zeta potential of the emulsion, Zeta potential of latex suspension with the increase of NaCl concentration first increased and then decreased slightly, with the increase of MgCl₂ concentration has increased, and The influences of MgCl₂ were more significant than NaCl at the same concentration; The addition of NaCl and MgCl₂ can increase the viscosity of chlorfluazuron SC, but the results different. In the studied range of MgCl₂ concentration, non-Newtonian index n of emulsion is less than 1, and decreased slightly with increasing concentration.3 Adsorption Characteristics of the dispersants MOTAS on the surfaces of chlorfluazuron particles were determinated respectively,and the dispersion stabilization mechanism of the suspension was discussed. The adsorption of dispersants MOTAS on the surfaces of chlorfluazuron particles impacted by temperature, pH and salt ions besides the properties of material. The results of IR and UV spectra showed that the adsorption of dispersant MOTAS on the interface of chlorfluazuron particle is physical adsorption, hydrogen bond andÏ€-Ï€conjugation effect was the main acting force between dispersant molecules and the surface of chlorfluazuron. The adsorption of dispersant MOTAS on the interface of chlorfluazuron particle can be considered as a single molecular layer adsorption, and Langmuir adsorption isotherm can be used for nonlinear fitting, the adsorption capacity increases with temperature then decreased. The adsorption of dispersant impacted by pH value and salt ions, adsorption capacity of dispersant increased with pH value of the increase first and then decrease, with the increase of salt concentration adsorption first decreases and finally stabilize. Desorption experiments showed dispersants and chlorfluazuron particle surface there exists strong intermolecular forces, and further show that the hydrogen bonds andÏ€-Ï€conjugate effect of dispersant molecules and the surface binding chlorfluazuron important force.