Preparation and slow-release performance of modified poly (butyleneadipate-co-terephthalate) melt-coated urea pellets

The current use of environmentally friendly slow-release fertilizers in agriculture is important for solving mitigating environmental pollution caused by the low utilization of fertilizers. In this study, modified biodegradable poly (butyleneadipate-co-terephthalate) (PBAT) based melt coated slow-release urea is prepared, avoiding the use of organic solvents. PBAT is modified with titanium tris(dodecylbenzenesulfonate) isopropoxide (TDBSP), which reduces the molecular weight and crystallinity. The addition of acetyl tributyl citrate (ATBC) as a plasticizer further improves the flowability of the material to satisfy the requirements of melt-coated urea. The ability of TDBSP to affect crystallization and result in branched behaviors in PBAT is demonstrated via differential scanning calorimetry (DSC) and rheological studies. The PBAT coating material is prepared by adding 1 % w/w of TDBSP and 35 % w/w of ATBC (% w/w dry PBAT basis), which constitutes 18 % of the urea mass by weight when coated. Scanning electron microscopy results show that the coating material exhibits the best coating effect on urea pellets. Results of the soil column leaching test show the slow-release performance of the coated area as well as the release of nutrients from the coated urea of 80.09 % after 28 d. By applying a single application of coated slow-release fertilizer in tobacco plant cultivation, the growth data of the tobacco plant is better than that of a topdressing applied after 30 d in conventional cultivation (under the same amount of fertilizer application), while labor cost is saved.