Studies On The Factors Influencing The Performance Of Pesticide Water Dispersible Granule

Water dispersible granule(WDG) was a new kind of pesticide formulations product developed since the 1980 s, which requires no organic solvents in its preparation and application, and avoids the environmental pollution. Disintegration property is an important parameter for evaluating the performance of pesticide water dispersible granules(WDGs).In this study, we investigated the effects of pore size and pore-size distribution formed during granulation and the drying process on the disintegration property of WDGs. ammonium bicarbonate was added to 10% difenoconazole WDG formulations as the pore-forming agent. The dispersant and other additives were also selected and optimized for being used in the formulation of 10% difenoconazole WDG. It was found that the pore sizes of 10% difenoconazole WDGs, prepared by adding NH4HCO3 as the pore-forming agent, were mostly within 4-25μm. Among different drying methods, the vacuum-drying technique was responsible for a bigger capillary porosity, due to the more rapid evaporation of water. The chemical structure of an anion dispersant was also a major determining parameter affecting disintegration properties of WDG. SSMA with different hydrophilic to hydrophobic group ratios were synthesized and applied to the 10% Difenoconazole WDG formulation to prepared WDGs. Larger pore sizes of WDGs prepared with a stronger hydrophobic polycarboxylate dispersant were obtained, as the water evaporation rate increased with increased hydrophobicity of WDGs during the drying process. The disintegration results of WDGs confirmed that a larger pore size was advantageous to the disintegration. Thus, we suggest that pore size is the key factor that significantly influences WDG disintegration performance.In addition, we also investigated the effect of polymer dispersant on suspension of inorganic fillings for pesticide WDG. The influences of dispersants on the suspension of corn starch, diatomite, bentonite, montmorillonite, precipitated silica and light calcium carbonate were systematically investigated by sedimentation experiments and summarized. Light calcium carbonate was selected as the research object in the paper. The results indicated that too many or too few of the dispersant amount influenced the stability of suspending system. These results are meaningful for the development of high-performance pesticide WDG.