Studies of factors influencing the disintegration performance of pesticide water dispersible granules

Abstract

Disintegration property is an important parameter for evaluating the performance of pesticide water dispersible granules (WDGs). The purpose of this study is to explore the effects of pore size and pore-size distribution formed during granulation and the drying process on the disintegration property of WDGs. It was found that the pore sizes of 10% difenoconazole WDGs, prepared by adding NH4HCO3 as the pore-forming agent, were mostly within 4-25 μm. Among different drying methods, the vacuum-drying technique was responsible for a bigger capillary porosity, due to the more rapid evaporation of water. 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.