Polyurethane Modified with Zeolite 4A for the Controlled Release of Urea

Pure polyurethane (PU) and its composites with zeolite 4A prepared through the in situ reaction were used as coating materials for urea. On the basis of analyzing their morphologies and structures, the effect of zeolite 4A content on release property of coated urea was investigated. SEM images showed the formation of the good interface between microsized zeolite 4A and polyurethane. When 2% of zeolite 4A was added into PU, the N release duration of coated urea reached 70 d, implying that PU/zeolite 4A composite can be used as an alternate strategy to improve the N use efficiency in controlled release fertilizer. [GRAPHICS] .