毒死蜱微胶囊制备中表面形貌和包封率的影响因素

Factors Affecting Morphology and Encapsulation Ratio of Chlorpyrifos Microcapsules with UF-resin During Preparation

采用原位聚合法以脲醛树脂为壁材制备了毒死蜱微胶囊,考察了制备过程中微胶囊表面形貌、包封率的影响因素,并测定了微胶囊的载药率。结果表明,固化阶段以0.5℃/min逐步升温、以20 r/min逐步降低搅拌速度和添加质量分数为0.4%NaCl溶液可以制备出表面形貌良好的微胶囊。不同囊芯与囊壁比对微胶囊包封率基本无影响,相互间差异不大;调酸速度和固化时间对包封率有较大影响,调酸过快和固化时间过短均导致包封率下降,适当的调酸时间为60 min,固化时间为100 min。在优化条件下制备的毒死蜱微胶囊平均载药达0.642 g/g,表明方法较适用于毒死蜱微胶囊的制备。

UF-resin was used to encapsulate chlorpyrifos via in-situ polymerization. The factors affecting the morphology and the encapsulation efficiency of the microcapsules were investigated, and the drug loading was also determined. The results show that at a heating rate of 0. 5 ℃/min, a stirring speed of 20 r/min and with 0. 4% sodium chloride added in the solidifying period, microcapsules with good shape could be prepared. Different core/wall ratios did not significantly affect the encapsulation ratio, and the encapsulation ratios for 12, 15, 18, 21 and 24 g UF-prepolymer solutions were 98.56%, 98.89%, 99.34%, 98.25% and 98.21%, respectively. However, acidification and solidifying time could affect encapsulation ratio evidently, and the optimum periods of acidification and solidifying were 60 min and 100 min respectively. The drug loading ratio of the microcapsules was as high as 0. 642 g/g.