Preparation of Slow-Release Coated Urea Based on C8-Maleic Anhydride Copolymer-Cured Epoxidized Soybean Oil

Abstract

Coated fertilizers have the advantages of high nutrient utilization efficiency, long release duration, and low environmental pollution, which play an important role in sustainable agricultural development. Organic polymers are commonly used coating materials of coated fertilizers, but still have limitation of high cost and nondegradability. In this work, a method to prepare coated urea (CU) with slow nutrient release characteristics by curing biodegradable epoxidized soybean oil (ESO) with low-cost C8-maleic anhydride copolymer (C8-MA) was developed. The effects of curing temperature, anhydride/epoxy group ratio, and imidazole content on the curing reaction were investigated. The coating material (CME) prepared with the molar ratio of anhydride to epoxy of 1:1 and 5 wt % imidazole at 100 °C exhibited a contact angle of 81.9°, which is more hydrophobic than that of C8-MA (68.1°). The water absorption and coating porosity of the CME was 5.9% and 2.5%, respectively, implying an excellent water resistance property. Scanning electron microscopy images of CU showed that the urea granules were completely wrapped by the CME, which had intact structure and smooth surface. The CU showed a sustained release behavior and the steady release can last a period of >28 days.

High-Impact Epoxy Resins with Superior Hydrophobicity Toughened by Epoxy Functionalized Poly(olefin-alt-maleimide) Derivatives

“…In previous works, we developed a facile and efficient heterogeneous polymerization method, named self-stabilized precipitation polymerization (2SP), − which is very suitable for the copolymerization of olefinic monomers and maleic anhydride (MAH). Taking 1-hexene as a model α-olefin, the poly­(1-hexene- alt -MAH) (PHMA) copolymer was efficiently synthesized, which can serve as a polymeric curing agent for EPs.…”

Preparation and characterization of liquefied eggplant branch bio-based controlled-release fertilizer

“…However, the low efficiency of traditional fertilizers has become a common problem in the application of chemical fertilizers [3]. Compared with traditional fertilizers, coated controlled-release ureas have the advantages of diversified coating materials, good controlled-release performance, and a simple production process [4,5]. The principle behind the use of the coating is to form a protective film on the surface of instant fertilizer particles to block water and delay nutrient release [6,7].…”

Humate increases nitrogen fertiliser efficiency and reduced N leaching

“…The N use e ciency of the most commonly used N fertiliser, urea, has been estimated from 15 N-labeled studies to be about 35% due to denitri cation losses from nitrous oxide, ammonia volatilisation and leaching 27 . This has led to development of new technologies, beyond environmental or fertiliser management practices, focusing on formulation of enhanced e ciency fertilisers with additives for controlled release [28][29][30] , including urease and nitri cation inhibitors 27,31 and organic polymers for improved N uptake from urea 32,33 .…”