Controlled Release Agents Of Pesticide Based On Clay

As a new pesticide dosage form,pesticide controlled-release agents have the advantages of environmental friendliness,good safety,slow release and high efficiency.It has outstanding technical advantages and wide application prospects in the field of modern agriculture.In this paper,the controlled-release agent of beta cypermethrin was prepared by using microcapsule,composite hydrogel and polymer composite membrane based on palygorskite.The morphology and structure of the controlled release agents were characterized with optical microscope,polarizing microscope,electron microscope and infrared spectrum,and their controlled release behavior in different release medium was compared.The main contents and conclusions are as follows:1.The Pickering emulsion was prepared with fibrous palygorskite dispersion as water phase and toluene as oil phase.Based on this,the composite microspheres were prepared by emulsion polymerization.The composite microspheres were used as the carrier and the beta cypermethrin as the model drug,and the drug release properties of the composite microspheres under different concentrations of ethanol-water solutions were investigated.The results showed that the composite microspheres were composed of palygorskite and polymer layer,and the composite microspheres were coated with palygorskite on their surface.The composite microspheres showed good swelling property.Cypermethrin was used as the drug carrier model to study the sustained-release performance of composite microspheres under different concentrations of ethanol solutions.The experimental results showed that the composite microspheres had a high cumulative release rate in high concentration of ethanol solution.Therefore,the release rate of the composite microspheres can be controlled by changing the concentration of ethanol water solution,so as to change its sustained-release performance.2.Palygorskite particles were added to the polyacrylamide hydrogel for the investigation.The effect of palygorskite as a crosslinking reagent on the structureand properties of the gel was explored.The results showed that with the increase of the contents of palygorskite,the water absorption of the composite hydrogel decreased gradually,and the thermal stability of the composite hydrogel increased significantly.The release time in the 60% ethanol aqueous solution lasted for 10 days to achieve the release equilibrium state,which greatly changed the sustained release property of beta cypermethrin.3.PVA-ST composite membrane was prepared by solution casting method.Some properties of the composite membrane were studied.At the same time,PVA-ST/cypermethrin sustained-release membrane was prepared with cypermethrin as model drug,and the structure and sustained-release performance of the membrane were studied.In order to better control the release of Cypermethrin in the sustained-release film,palygorskite loaded drug was introduced into the sustained-release film system to prepare palygorskite loaded pesticide sustained-release film.The results showed that the composite membrane with palygorskite content of 10% had optimal comprehensive performance.With the increase of palygorskite content,the water resistance of the slow-release membrane was significantly improved,and cypermethrin was evenly dispersed in the slow-release membrane.When PVA-ST/cypermethrin slow-release membrane was immersed in ethanol aqueous solution,the release rate became faster.The method of loading cypermethrin on palygorskite can effectively reduce the release rate of cypermethrin.In this paper,through the above three parts of research work,the objective of improving the high value-added use of palygorskite products was achieved.It also provides a theoretical basis and technical support for the future application of palygorskite in the fields of new pesticide dosage forms,drug release and other engineering fields.