Preparation Of Abamectin Capsule Suspensions And Research Of The Physical Storage Stability

To solve the photolysis and degradation by micro-organism in the soil, Abamectin capsule suspensions (CS) with methyl methacrylate as wall material were prepared by emulsion polymerization. The performance of entrapment rate, drug-loading rate, the controlled release effect and suspensibility were studied. And the influences of polymerization time, ratio of core material to wall material(core to wall) and percentage of SDS on the entrapment rate, drug-loading rate and mean size of CS were studied, stability at elevated and low temperature were also studied in this paper. In addition, the coordination influence of veegum and xanthan gum (XG), bentonite and XG to the physical storage stability of the CS were also studied in this paper.The microcapsules prepared by emulsion polymerization had regular shape, comparative small uniform mean size. The high entrapment rate was as high as 90.31% when the polymerization time was 4h. The CS could dispersed automatic in water and the suspensibility was as high as 99.95%. The results of release effects showed that, the abamectin CS has a good sustained release effect compared with the emulsion.The influences of polymerization time, ratio of core material to wall material (core to wall) and percentage of SDS on the entrapment rate, drug-loading rate and mean size of CS were studied. The results showed that, The entrapment rate, drug-loading rate and mean size of CS were positive correlation with the polymerization time. The entrapment rate and drug-loading rate were relatively steady when the polymerization time was more than 3 hours, and the change of mean size was obviously reduced when the polymerization time was more than 1 hours. The drug-loading rate and mean size were significantly affected by core to wall. As the core to wall increased, the drug-loading rate increased and the D50 minished. But it just had few influences on the entrapment rate. The influence of percentage of SDS on entrapment rate and drug-loading rate was not evident, but it was evident to the mean size. When the percentage of SDS was 8%, the D50 of CS was smallest and the particles were more uniform. It indicated that the acceptable abamectin capsule suspensions which had uniform mean size, regular shape, high entrapment rate and drug-loading rate could be made when the polymerization time was more than 3h, the core to wall was between 1:3 and 1:2 and the percentage of SDS was between 6% and 8%.The coordination influence of veegum and xanthan gum (XG), bentonite and XG to the physical storage stability of the CS were studied with rheometer. The results showed that, the use of veegum could obviously improved the physical storage stability. The separation ratios at normal and elevated temperature decreased with the increase of veegum. And when the amount increased to 2%, the separation ratios at normal and elevated temperature separately decreased form 80.00% and 73.91% to 0.83% and 5.83%. The results of reseach to its rheology showed that, the add of veegum transform the system from Newton's fluid to pseudoplastic fluid and generate obvious thixotropy. Compared with using veegum alone, the coordination action of veegum and XG was more obvious, 0.5% veegum and 0.3%XG could apparently improve the physical storage stability of CS. And as the increase of veegum, both the viscosity, shear stress and the thixotropy increased. The size of veegum influenced the physical storage stability of the system distinctly. Smaller veegum could decrease the separation ratio. The coordination action of bentonite and XG could also improve the the system's physical storage stability. When the dosage of bentonite was 15%, the XG was 0.5%, the system which had good suspension stability could be achieved. And with the increase of bentonite, the viscosity, thixotropy, yield value and stability of the system improved obviously. Anyone used lonely could not improve the physical storage stability.The CS diluted into 1200 times had a good wetting performance and comparatively small contact angle on the lamina of spinach, celery, rape, cotton the wax layer of which were thin. But the wetting performances were bad on the lamina of cabbage, maize and wheat the wax layer of which were thick, and the contact angles were big. In the add of 0.05% Silwet 408, the surface tension decreased obviously, and the contact angles decreased to 0 on all 7 plants we selected. Apart from the spreading areas on the cotton raised 4.68 times, it raised 24.83-88.17 times on the other 6 plants. The results showed that, the organic silicon surfactant Silwet408 could reduce the surface tension and contact angles of CS obviously. it could improve the wetting performance on the plants.