Studies On The Processing Technology Principles Of Hexaflumuron SC And Its Properties

The pesticide formulations of hexaflumuron SC was selected ,and dispersion stabilization mechanism of the suspension, rheological behaviors of the system impacted by different factors were studied, and the activities of hexaflumuron agents with different additives were compared in this paper.Based on traditional selecting methods of suspension dispersants, particle size ,viseosity and surface tension of different dispersants were determined, and MOTAS and NNO were employed as excellent dispersants for hexaflumuron SC.The optimum amount of dispersants was around 3%. Moreover, thickening agent,Defoamer and antifreeze glycol were detected. The optimal formulations of hexaflumuron SC was as follow: hexaflumuron 20%,wetting dispersing agent (NNO or MOTAS) 2.5-3%, thickening agent xanthan gum 0.2%, antifreeze glycol 2%, Defoamer 0.1%, fill water to 100%.The product in all respects conformed to the requirements for a suspension concentrate. But Hexaflumuron SC processed with MOTAS had better property than that with NNO based on analysis in size, suspension rates, analysis of water rates,viscosity, and other indicators.Adsorption Characteristics of the two types of dispersants on the surfaces of hexaflumuron particles were determinated respectively,and the dispersion stabilization mechanism of the suspension was didcussed. The results showed that hydrogen bond was the main acting force between dispersant molecules and the surface of hexaflumuron, and the force of the hydrogen bonds of polycarboxylic acid type dispersing agent MOTAS was significantly higher than naphthalene sulfonic acid type dispersing agent NNO. The saturation adsorption amount of two dispersants increased respectively with increasing the vdispersants molecular weight, and the saturation adsorption amount of NNO on the hexaflumuron surface was lower than that of MOTAS obviously, 4.623mg.g-1 and 5.943mg.g-1 respectively. The adsorption conformation of the two types of dispersants on hexaflumuron surface were between trains and tails, dispersing agent NNO was closer to trains conformation. The negative of hexaflumuron particles was increased after adsorption MOTAS and NNO, and the potential of particles adsorption MOTAS was significantly higher than that NNO, and the electrostatic repulsion between MOTAS and hexaflumuron particles was significantly higher. The surface adsorption equilibrium time of NNO was shorter,and the adsorption rate was more rapidly. The adsorption layer thickness of MOTAS on the hexaflumuron surface was 8.00nm, greater than that 5.97nm of NNO. Because of a strong negative charge after adsorbed dispersant on the hexaflumuron surface and the strong hydrogen bonds, the hydration membrane was formated in the outer layer, Bound Water of hydration membrane with NNO , MOTAS and without these was 4.92%, 7.12%, 1.99% respectively, thus the high stability of the suspension was attributed to the electrostatic repulsion synergistically and the steric interactions. Therefore, the dispersion stability of hexaflumuron SC with MOTAS was higher than that with NNO.The rheological behaviors of hexaflumuron suspension were studied. The five rheological model were used to the curve fitting of the hexaflumuron suspension with NNO and MOTAS. The Herschel-Bulkley rheological model which was highest correlation coefficient R2 was determined to fit the rheological curve of pesticide SC. The effects on the rheological behavior of suspensions were studied, such as the content of hexaflumuron, the type and the content of dispersant dosage, the type of electrolyte, the pH value of water, and so on. The"shear-thinning"behavior were obvious in terms of hexaflumuron SC both with MOTAS and NNO. With the molecular weight of dispersant increasing, the yield values decreased, and the flow behavior index increased.With the content of xanthan gum increasing, the viscosity increased, the yield valueτH increased, the flow behavior index n decreased, and the pseudoplastic phenomenona was more obvious, and xanthan gum was structural adjustment.The viscosity of suspensions were increased through cold and thermal storage. The viscosity of hexaflumuron SC with MOTAS dispersant changed slightly, and its yield value and flow behavior index were almost maintains stable, but the viscosity of hexaflumuron SC with NNO dispersant changed significantly. in particularly, its yield and flow behavior index values were significantly increased, and it tend to bulging plastic fluid after thermal storage . The viscosity, the yield valueτH and the flow behavior index n of hexaflumuron SC were gradually bigger with the increasing the days stored at room temperature. The hexaflumuron SC with NNO dispersant were significant variations compared with MOTAS.The nature of plant leaves, pesticides liquid and the nature of the interface that pesticide liquid spraying to plants and plant leaf formation of solid, liquid, gas would influence the effects of the retention of liquid. According to the target critical surface tension, the wetting, spreading situation of the different of surface tension of the liquid on the targets would be predicted. The critical surface tension of the cabbage and cotton leaves tested in this research, the value were 35.4mN/m, 63.7mN/m respectively. The cabbage leaf surface which difficult to be wet, the maximum retention would obtain at 80-100mg/L liquid of hexaflumuron SC or EC, and then the concentration increasing, the quantity of retention was slightly increasing, but limited. The cotton leaf surface which more easy to wet, the maximum retention would obtain at 40-60mg/L solution of hexaflumuron SC or EC, and then the concentration increasing, the SC quantity of retention increased slightly, but the EC liquid retention declined. Therefor, the desired retention was attributed to appropriate concentration of the preparation, otherwise , the fluid would be loss, and the retention decrease..There was no difference in toxicity by testing the diamondback moth (Plutella xylostella) 3rd larvae and the cotton leaf roller (Syllepta derogata) 3rd larvae with three different formulations of hexaflumuron useing the leaf sandwich test, the results illustrated that the processing aids had no difference in toxicity among the formulations. The results of the dipping insects body test showed that the toxicity of hexaflumuron EC was slightly higher than hexaflumuron SC, and the toxicity of hexaflumuron SC is slightly lower than that of hexaflumuron EC for the diamondback moth (Plutella xylostella) 3rd larvae with the dipping cabbage leaf test, but the toxicity of hexaflumuron SC was significant higher than that of hexaflumuron EC with the dipping cotton leaf test for Syllepta derogata 3rd larvae, the above-mentioned results showed that there was positively correlated between the toxicity and the volume of fluid retention on plant leaf.Therefore, the appropriate selection of the liquid surface tension should be selected based on the crops and the control object of pesticide formulation processing, but not only reducd the liquid surface tension. The optimum liquid surface tension was slightly lower than the critical surface tension, the surface tension was too high, the liquid was difficultly to be wetted and spread on the target, and liquid had a serious loss; but the surface tension was too low, the liquid on the target was easy to expand and wet, the thinner film formated and the loss of liquid increased.