In this work, castor oil-based polyurethanes were prepared through rotating-drum coating technology as encapsulating coating materials for slow-release fertilizers. The physico-chemical properties and microstructure of the polyurethanes were tailored by selection of diisocyanates, control of the hydroxyl number of castor oil used, and controlling the hydroxyl/isocyanate molar ratio. The effect of the microstructures and the composition of the resulting polyurethanes on the controlled release behavior of coated urea granules were evaluated by measuring the N release characteristics of the system in water under laboratory conditions. In addition, the critical mechanisms underlying the polyurethanes’ structures and properties are clarified and discussed. The results show that isophorone diisocyanate, and 2,6-diisocyanatotoluene as the hard segment are not suitable for production of slow-release fertilizers while polymethylene diisocyanate does. The N release longevity of SRFs coated with only 5.0 wt% of polyurethane can be tuned from 20 days to 140 days, constituting the widest range reported in the literature to date. The high hydroxyl number of castor oil and high content of NCO in the polyurethanes prepared lead to a high crosslink density, hydrophobicity, and compact micro-structure, resulting in a material that exhibits low water and nutrients permeabilities, and therefore slow release. This work offers a simple and effective method to create slow release fertilizers that is cost-effective and environmentally friendly.

在这项工作中，通过转鼓包衣技术制备了蓖麻油基聚氨酯，作为缓释肥料的包封包衣材料。通过选择二异氰酸酯，控制所用蓖麻油的羟基数以及控制羟基/异氰酸酯的摩尔比来调整聚氨酯的物理化学性质和微观结构。通过在实验室条件下测量系统在水中的氮释放特性，评估了所得聚氨酯的微结构和组成对包衣尿素颗粒控释行为的影响。此外，阐明和讨论了聚氨酯结构和性能的关键机理。结果表明，异佛尔酮二异氰酸酯和2 作为硬链段的6-二异氰酸根合甲苯不适合生产缓释肥料，而聚二甲基亚甲基异氰酸酯则适合。仅涂有5.0 wt％聚氨酯的SRF的N释放寿命可以从20天调整到140天，构成了迄今为止文献中报道的最大范围。所制备的聚氨酯中的蓖麻油的高羟基值和NCO含量高，导致高交联密度，疏水性和致密的微观结构，导致这种材料表现出低的水和养分渗透性，因此释放缓慢。这项工作提供了一种简单有效的方法来生产经济高效且环保的缓释肥料。仅涂有5.0 wt％聚氨酯的SRF的N释放寿命可以从20天调整到140天，构成了迄今为止文献中报道的最大范围。所制备的聚氨酯中的蓖麻油的高羟基值和NCO含量高，导致高交联密度，疏水性和致密的微观结构，导致这种材料表现出低的水和养分渗透性，因此释放缓慢。这项工作提供了一种简单有效的方法来生产经济高效且环保的缓释肥料。仅涂有5.0 wt％聚氨酯的SRF的N释放寿命可以从20天调整到140天，构成了迄今为止文献中报道的最大范围。所制备的聚氨酯中的蓖麻油的高羟基值和NCO含量高，导致高交联密度，疏水性和致密的微观结构，导致这种材料表现出低的水和养分渗透性，因此释放缓慢。这项工作提供了一种简单有效的方法来生产经济高效且环保的缓释肥料。所制备的聚氨酯中的蓖麻油的高羟基值和NCO含量高，导致高交联密度，疏水性和致密的微观结构，导致这种材料表现出低的水和养分渗透性，因此释放缓慢。这项工作提供了一种简单有效的方法来生产经济高效且环保的缓释肥料。所制备的聚氨酯中的蓖麻油的高羟基值和NCO含量高，导致高交联密度，疏水性和致密的微观结构，导致这种材料表现出低的水和养分渗透性，因此释放缓慢。这项工作提供了一种简单有效的方法来生产经济高效且环保的缓释肥料。