ABSTRACT

Polyurea microcapsules containing oxyfluorfen herbicide were synthesized by interfacial polymerization reaction between toluene diisocyanate and ethylene diamine at various core to shell ratios using green solvent N-N-dimethyldecanamide as carrier medium and using biodegradable PVA203S and Kraft lignin grade (varying molecular weight) as the emulsifying agent. The study was done to understand the effect of stirring rate on preparing microcapsules and find out how the process conditions changed the attributes of microcapsules such as particle size distribution, encapsulation efficiency and release kinetics. The formation of capsules was confirmed by FT-IR, SEM and TGA. The study indicated that the encapsulation efficiency decreased with increasing core to shell ratio. The change in release kinetics was based on the stirring rate and was dependent on the pH of release medium. Particle size distribution was influenced by the agitation speed during formation of emulsion. Kraft lignins of varying molecular weight were used to synthesize the polyurea capsules. It was found that capsules with high molecular weight lignin showed slow and sustained release. Synthesized polyurea capsules was subjected to safety study on paddy crop and compared with commercially available oxyfluorfen and was found to be safe for use on paddy crop.

摘要

采用绿色溶剂N - N通过甲苯二异氰酸酯与乙二胺在不同核壳比下的界面聚合反应合成了含氟乙草胺除草剂的聚脲微囊。-二甲基癸酰胺作为载体介质，并使用可生物降解的PVA203S和卡夫木质素等级（分子量变化）作为乳化剂。进行这项研究是为了了解搅拌速率对制备微胶囊的影响，并了解工艺条件如何改变微胶囊的属性，例如粒径分布，包封效率和释放动力学。通过FT-IR，SEM和TGA证实了胶囊的形成。研究表明，随着核壳比的增加，封装效率降低。释放动力学的变化基于搅拌速率，并且取决于释放介质的pH。粒径分布受乳液形成过程中搅拌速度的影响。使用不同分子量的硫酸盐木质素来合成聚脲胶囊。发现具有高分子量木质素的胶囊显示缓慢且持续的释放。对合成的聚脲胶囊进行了稻谷作物的安全性研究，并将其与市售的氟草醚进行了比较，发现可以安全地用于稻谷作物。