Preparation of Poly(l-lactic acid) Capsule Encapsulating Fertilizer

摘要

In this work, poly (l-lactic acid) (PLLA) microencapsulated urea as fertilizer was prepared in water in oil in water (W/O/W) system. PLLA used as capsule shell was prepared by polycondensation of l-lactic acid with p-toluene sulfonic acid as a catalyst at 140°C. The prepared PLLA was used to encapsulate urea. Firstly, the aqueous urea solution was dispersed in oil solution of PLLA and chloroform containing polyvinyl alcohol (PVA) as a stabilizer with stirring at 800 rpm. Secondly, the water in oil emulsion was subsequently dispersed in PVA aqueous solution by stirring at 800 rpm to form W/O/W emulsion. Then, it was stirred for approximately 12 hours to evaporate chloroform in the system resulting in the formation of PLLA microencapsulated urea. It was finally centrifuged and dried in vacuum oven. The influence of water and oil phase ratio on the formation of capsule was studied. The obtained capsule was observed with an optical and scanning electron microscopes.