The effect of utilization bioblend polystyrene/polycaprolactone [PS/PCL] (F1, F2, F3, F4, F5) and bioblend polystyrene/starch [PS/starch] (F6, F7, F8, F9, F10) coating toward the thickness of the film formation and release of active substances urea granules had been studied. In this study, urea granule coated with bioblend PS/PCL with different variations of the number of PS. Evaluation of the original urea granule and product includes granules size distribution, film thickness measurement, and the release rate of urea in distilled water testing media. Results showed that bioblend polystyrene has a slow release characteristics because the release rate is lower than the noncoating urea granules. Spray coating method can produce urea granules with size of 1.5 - 3 mm with the film thickness range from 0.125 - 0.196 mm. According to the release kinetics model of order 0 with r values for the formula 2, 3, 4 and 5 respectively are 0.9992; 0.9995; 0.9997; 0.9992. Release of urea following the zero-order kinetics model means the release of urea occurs constantly from beginning to end. As for the formula 1, 6, 7, 8, 9 and 10 following the release kinetics model of Langenbucher, with the value of r for formula 1, 6, 7, 8, 9 and 10 respectively are 0.9927; 0.9582; 0.9779; 0.9591; 0.9330; 0.8990. The release following the urea kinetics model of Langenbucher means diffusion and erosion process happened in solution fraction, where there is no lag time or slow release at the early stage.
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