Preparation and characterization of polyurethane based on dimer acid for environment-friendly controlled release fertilizers

The paper presents a new controlled release fertilizer coated by dimer acid-based polyurethane (PU). The structure and property of the sample were characterized. Results indicated that the polyether polyol modified PU (MPU) coating reduced water absorption rate by 72.1% after 29 d, and increased the cross-linking density by 23%, and decreased the coating porosity by 26%, Moreover, MPUFs and PUFs both exhibited excellent nutrient controlled release abilities, especially the MPUF possessed longer nitrogen release longevity (118 d,131%) compared with PUF (51 d). Thus, the high-performance MPUFs with environmentally friendly and excellent controlled release could be widely applied to agricultural fields.