Preparation And Properties Of Polymer-coated Urea

The membranes of epoxy resin, polyethylene, polyvinyl-chloride, polystyrene and urea-formaldehyde were prepared. The permeability of the membranes correspondingly prepared with five kinds of materials was studied. The effect of membrane thickness on the permeability of membrane was investigated. The permeability and the nitrogen release feature of the coated urea by the five kinds of materials were predicted. The efficacy of using colorimetry with dimethyl-benzaldehyde for evaluating the releasing rate of the coated urea was investigated. It is found that this method is stable and accurate. The suitable testing conditions of using colorimetry with dimethyl-benzaldehyde were established. The simple tumbling coating technique was used to coat urea with Epoxy resin. The result shows that the membrane processes and conditions have great effects on the permeability. The permeability of urea-formaldehyde membrane is lowest , that of PVC is best, and that of epoxy resin, polyethylene and polystyrene is approximate. It is found that, the slow release property of the forecast coated urea is better than of the actual coated urea. The coating processes and conditions have the very tremendous influence on the slow release property of the actual coated urea.