The NR-g-ST was achieved to graft with modified ST and K2S2O8
as a catalyst for coating the granular fertilizer to reduce solubility
in water. The structure modified NR was confirmed by ATR-FTIR.
In medium water, the swelling ratio of the modified NR decreased
as function of ST due to hydrophilic behavior of ST incorporation in
NR matrix. In addition, the tensile strength of modified NR in the
presence of ST at 50 phr was the highest compared to other sample and the thermal stability modified NR-g-ST was higher than
that of NR-g-ST, which was confirmed by TGA. After NR grafted
with ST, it can lead the intermolecular linkage between ST and NR
molecules therefore the hydrophobic groups of NR were reduced
to control releasing urea fertilizer from capsule. The NR-g-ST membrane displays a good barrier for controlling release ofurea fertilizer
from capsule and easily degraded in soil. This product with good
controlled-release and water-retention could be especially useful
in agricultural and horticultural applications.