The Effect Of Fillers On Physical Properties Of Biopolymer Nanocompisite Material For Urea Coating

The concept of slow release fertilizers (SRF) is the latest technology available in fertilizer industries since 1963. The objective of this technology is to gradually release the nitrogen and other nutrients from the urea granules through a coating material so that the volume of nitrogen as well as other nutrients to be absorbed by crops can be maximized and the nutrients loss into the soil through leaching will be minimized. There are many types of coating materials that had been used such as wax, sulfur and polymer but they are not environmentally friendly.
A biopolymer nanocomposite material has been developed from starch, citric acid and polyvinyl alcohol (PVA) to be the coating material for the urea granules since it is more environmental friendly compared to the other coating materials. However, the problem arises when urea granules that had been coated by the biopolymer nanocomposite materials have rough surface. This is not a good characteristic for a coating material because as the surface is rough, the rate of nutrients release through the coating material will not be equally the same from one point to another.
In order to overcome this problem, fillers which are bentonite, kaolin, halloysite and nanoclay were mixed together with the biopolymer nanocomposite materials. The weight percentage of fillers added are varies from 1 wt.%, 2 wt.%, 3 wt.% and 4 wt.% while the ratio of PVA/starch/citric acid used is 1:3:2 respectively. The effect of fillers on biopolymer coating material in term of its water solubility, degree of swelling and surface roughness had been studied. The experimental results showed that the addition of 2 wt.% of halloysite reinforced into biopolymer material had the lowest percentage of degree of swelling and water solubility. The smoothest surface of biopolymer film was achieved when the biopolymer material mixed with 2 wt.% of halloysite