【作者】 张青华；

【导师】 路福绥；

【作者基本信息】 山东农业大学 ， 农药学， 2009， 硕士

【摘要】 1.本文通过对乳化剂的筛选,对抗冻剂、悬浮助剂的选择,确定了20%甲草胺水乳剂的优化配方: Span80:Tween20=1.2:1(质量比)的复配乳化剂: 5% ;正丁醇3%丙三醇: 5% ; 67%的甲草胺二甲苯溶液:30% ;其余用水补足至100%。2.对20%甲草胺水乳剂的流变特性进行了测定,研究结果表明20%甲草胺水乳剂为塑性流体,其粘度随温度的升高而降低,但变化幅度不大。3.通过六种加工方法(a:将乳化剂溶于水中,在速率为1250r/min磁力搅拌下,逐滴滴入甲草胺的二甲苯溶液中。滴加完后继续搅拌20min。b:将乳化剂与甲草胺溶液均匀混合,向其中逐滴加入重蒸水,其他条件同a。c:将甲草胺溶液逐滴加入到乳化剂的水溶液中,其它条件同a。d:将乳化剂与甲草胺溶液均匀混合,逐滴滴入到水中,其它条件同a。e:将Span80与甲草胺溶液混合,将Tween20溶于水中,将水相滴入油相,其他条件同a。f:将Span80与甲草胺溶液混合,将Tween20溶于水中,将油相滴入水相,其他条件同a。)制备甲草胺水乳状液并用激光粒度仪对其粒径进行了测定,观察了其稳定性;通过对其流变特性的研究,探索了其稳定机理,并经显微镜证实。结果表明,不同乳化过程所得乳状液具有不同的粒径分布,采用相转化法可得到较小粒径的乳状液。乳化剂先溶于油相生成的乳状液粒径较小且分布范围较窄。4.进一步通过电导率法及粘度法对相转变法制备甲草胺乳状液过程中粒径的大小、结构及流变特性的影响进行了研究,初步对其相转变机理进行了探索。研究结果表明,两种相转变法制备甲草胺乳状液的过程中,体系的粘度在随含水量的增加时,均经过一最大值,微观上表现为液滴的紧密堆积。更多还原

【Abstract】 The following aspects were studied in this thesis :1. We have screened out the emulsifers, cryoprotectan and suspending agent by measuring the particle size and stability of different formulations of acetochlor emulsion in water, then the best formula of acetochlor emulsion in water was ascertained as follows: Span80:Tween20= (the rate of weight as1.2:1): 5% N-butanol:3% Glycerol: 5% ; The 67%solution of Alachlor in dimethylbenzene:30% ; The rest was water.2. The rheological characteristics of Alachlor emulsion in water was measured. The results showed that its fluid form behaves as plastic fluid and its viscosity was lowered in extent with temperature raises.3. Formation of emulsions has been studied in the system water/Tween20+Span80/alachlor by six emulsification methods: a: stepwise addition of a water-surfactant mixture to oil, b: stepwise addition of water to a oil-surfactant mixture, c:stepwise addition of oil to a solution of surfactant in oil, d:stepwise addition of a oil-surfactant mixture to water. e:Tween20 in water and Span80 in oil , stepwise water in oil.f: Tween20 in water and Span80 in oil ,stepwise oil in water .Their particle size was determined by laser particle sizer, and their stability mechanisms were derived from determining their rheological characteristics and verified by the microphotographs. The results indicate that the emulsions that produced by different emulsification methods have different particle size distributions . Significant difference exists on drop size, drop size distribution, emulsion stability, and structure when emulsion was produced under different emulsification processes. For the different micellization and absorption ability of emulsifier in water phase and oil phase, the drop size is smaller and emulsion liquid is more stable when emulsifier is added to oil phase first for the ultra-low interfacial tension developed during phase inversion. Three-dimensional network generates for the weak flocculation among drops, and this structure delay the sedimentation.4. The particle size, microstructure and rheological characteristics of acetochlor emulsions prepared by different emulsification processe were further studied by particle determination, conductivity and viscosity methods.The results show that the viscosity for the system prepared by phase inversion methods both passed a maximum value with the content of water varied, and the moment of which the droplets were closed-packed in microstructure.更多还原