| Suspension concentrate was able to save organic solvent and reduce environmental pollution, relative to human and animal safety, high efficacy and low cost, which was becoming a hot research and development at home and abroad. However, the physical stability's control of pesticide suspension concentrate had not been solved, which restricted the healthy development of pesticide suspension concentrate.This thesis had chosen oxyfluorfen as the research objects. We did more research about the physical stability of pesticide suspension concentrate from the rheological point of view.,and the effects of the dispersion agent, salt ions, pH value on the dispersion stability of oxyfluorfen suspension concentrate by means of measuring Zeta potential, average size analysisThe purpose of this thesis is to study the thixotropic suspension of pesticides in thematrix in the mechanism of thixotropic, external factors on the physical stability of suspension. Approach is steady shear, laser particle distribution instrument and Zeta potential measurement method of combining. The results show that Thus zeta potential value of the suspension concentrate had a good correlation to the average particle diameter. Therefore the dispersing effect of wetting dispersant in suspension concentrate could be well represented by the zeta potential value. The rheological characteristics and thixotropy of mixed suspension system were increase after the thixotropy matrix mixing. pH affected the physical stability's of pesticide suspension from the ionization of the dispersant. The presence of Mg2+ can affect the physical stability of suspensionThe following aspects were studied in this thesis:1. Zeta potential method with laser particle distribution instrument were used to select dispersant agent in preparing 25% oxyfluorfen suspension concentrate in this study. The results showed that numerous species of dispersant agent adsorbed at the surface of oxyfluorfen qranule. Incongruently. Alone SOPA-270 adsorbed at the surface of oxyfluorfen qranulewell.When mass fraction of the mixture was 3%,│ζ│could reach the maximum and the average particle diameter of the system was smallest. The changes of│ζ│and Dav was very small after heat storage treatment, and the corresponding system achieved the best dispersion effect. 2 In this paper, we have studied the rheology of MT and HTlc . The results showed that the flow behavior of MT aqueous solution showed the pseudoplastic fluid characteristics in range of research. The flow behavior of 2%-3% (w/w) MT suspensions showed the positive thixotropy, so the recovery of particle structure changed from dispersed particles to the network structure. In the n(Fe)/n(Mg) =1/3,1/4,1/5,1/6 decentralized system of four HTlc ,the rheological characteristics and thixotropy of the n(Fe)/n(Mg) =1/6 were max in a certain concentration and with increasing the system concentration, the system thixotropy changed from the negative thixotropy then to the positive thixotropy.3 MT was added to HTlc suspension. The results showed that mMT/ mHTlc=0.40/1.60(w/w) showed positive thixotropy in different proportions of mMT/mHTlc,oters showed negative thixotropy. With the minishing retio of mMT/ mHTlc,suspension system thixotropy changed from the negative thixotropy then to the positive thixotropy. The rheological characteristics and thixotropy of mixed suspension system were increase after the thixotropy matrix mixing.4 pH of media affected the physical stability's of pesticide suspension from the ionization of SOPA-270.With pH added,│ζ│could augment, Electrostatic interaction reinforcing, At the pH value of 8 the dispersion stability of suspension concentrate was best.5 Under different pH Mg2+ was able to decrease Zeta potential by compressing the electronic double layer thickness of particles surface, which could lead to particles aggregation due to the reduction of electric quantity and ultimately make the dispersive effect of suspension concentrate worse, then the higher the content of Mg2+ was, the worse the dispersion stability was. |
