Studies On The Stable Mechanism Of System Of Beta-cypermethrin EW

Emulsion in water (EW) is a thermodynamic instability dispersed system, there are so many difficulties in developing a successful prescription owing to complex compositions. By taking beta-cypermethrin as the research object, three prescriptions were prepared. The work for the forming mechanism of system of EW were also primarily related by means of scattering technology and laser particles size measurement combining quality parameters of EW. All the results could provide the theoretical basis of the mechanism and practice guidance.After the prescriptions were developed, preparing method of beta-cypermethrin EW was inversed phase emulsification by high shearing mixing emulsor with continuous cutting at the rate of 5000r/min in 3min. The results showed increasing speed and prolonging cutting time could not improve the stability of EW.Evaluating the stability of EW with scattering technology, Stability Index (SI) from Turbiscan Lab Dispersion-stability Analyzer can be used as quantitative indicator to evaluate the physical stability of preparing beta-cypermethrin 45EW. Furthermore, the results of the orthogonal experiment indicated that the emulsifier's ratio was the most important factor that affect the stability of EW, while co-emulsifier content and water quality had less effect, and the difference of the effects of co-emulsifier content and water quality was not significant. After emulsifier's ratio was selected, water quality and co-emulsifier had synergetic effects on physical stability of beta-cypermethrin 45EW.The relationship between stability and different factors were researched by changing the dosage and kinds of prescriptions.Kinds and content, the HLB value and structure of emulsifier were also correlated with physical stability of EW. There is a close relationship between HLB value and particle size and distribution. Qualified and stable emulsion in water can be prepared up to a certain amount emulsifier after being selected. The anti-coalescence of emulsion stabilized exist correlation with the structure of emulsifier, it will be improved with length of the saturated carbon chain of lipophilic group.Co-emulsifier content could affect the physical stability of EW, co-emulsifier with long carbon chain was more favorable for improving the stability, when using straight chain alkyl alcohol..Physical stability of EW decreases with the hardness of water increasing. Adjusting the content of co-emulsifier could improve on the suitability of water quality. The tap water could be used to prepare the beta-cypermethrin 45EW.