No abstract

Triple polymer coated with controlledrelease water retention fertilizer (TCWF) and enhanced mechanical property was developed by coating polyethylene (first layer), poly (acrylic acid-co-acrylamide) superabsorbent (second layer), and poly (butyl methacrylate) (third layer) consecutively on the granule core urea in the fluidized-bed coater. The inner layer possessed controlledrelease property, the middle layer had water absorbent characteristic, and the thin outer layer aimed to protect the fragile layer of the superabsorbent. The relationship between the thickness of coating layer and the nutrient releasing properties was established. The effects of polymerization parameters on the water absorbency of the superabsorbent were studied and optimized as well. The nutrients release behaviors of this triple-coated urea in both water and soil were investigated and compared. The results showed that TCWF not only performed as a good controlled-release fertilizer but also had excellent water retention capacity.

No abstract

No abstract

Esters derived from 1‐naphthylacetic acid (NAA) and polyacrylate were synthesized and a dual controlled‐release formulation was developed by coating fertilizers with these esters. FT‐IR, 1H NMR, TGA, and DSC were used to characterize the synthesized polymers, and the mechanical properties were also tested. Urea granules were coated with NAA esters, and the release rates of urea from the coated granules in water were measured. NAA release from the esters was performed in different buffer solutions and in soil. The results showed that the coated fertilizers were able to release urea in a controlled pattern and that NAA could be slowly released from membranes of the esters in both buffer solutions and in soil through hydrolysis. The coated fertilizer's availability could last more than 28 days and that of NAA could last more than 12 months, which suggested that the prepared CRF possessed dual controlled‐release of urea and NAA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013