Controlled-release urea was fabricated by coating urea particles with a polymer latex in a fluidized bed. The latex film coated on the urea particle surface was hydrophilic and swelled in water. The film swelling in w...Controlled-release urea was fabricated by coating urea particles with a polymer latex in a fluidized bed. The latex film coated on the urea particle surface was hydrophilic and swelled in water. The film swelling in water and urea solution and properties of the swollen film were studied. The film swelling in urea solution followed the Lagergren＇s pseudo-first order kinetics with the swelling coefficient depending on the film material and experimental conditions. The effects of swelling on film structure and permeability were studied. The film permeability coefficient decreased with increasing swelling ratio with an approx- imately linear relationship. Based on the film formation process and structure of the swollen film. a film structure model consisting of dense and swollen phases was proposed. The permeability coefficient of the spherical film and cumulative release of urea from the coated particles were calculated from the swelling ratio of the spherical film. which was determined from the expansion curve of the coated particle during the release process, The calculated and measured release curves agreed well, This research indicates that the swelling of the hydrophilic film and the controlled-release mechanism are important factors in the development of controlled-release urea.展开更多
基金The authors express their gratitude for the financial support of this study by the National Natural Science Foundation of China （NSFC No. 20876085）.
文摘Controlled-release urea was fabricated by coating urea particles with a polymer latex in a fluidized bed. The latex film coated on the urea particle surface was hydrophilic and swelled in water. The film swelling in water and urea solution and properties of the swollen film were studied. The film swelling in urea solution followed the Lagergren＇s pseudo-first order kinetics with the swelling coefficient depending on the film material and experimental conditions. The effects of swelling on film structure and permeability were studied. The film permeability coefficient decreased with increasing swelling ratio with an approx- imately linear relationship. Based on the film formation process and structure of the swollen film. a film structure model consisting of dense and swollen phases was proposed. The permeability coefficient of the spherical film and cumulative release of urea from the coated particles were calculated from the swelling ratio of the spherical film. which was determined from the expansion curve of the coated particle during the release process, The calculated and measured release curves agreed well, This research indicates that the swelling of the hydrophilic film and the controlled-release mechanism are important factors in the development of controlled-release urea.
