The effects of hypochlorite level, i.e. 0.5; 1 and 2 active chlorine g/100g starch, on the properties of oxidized maize starch were investigated by FT-IR and solubility of oxidized starch and starch film. The obtained results shown that there was no difference of IR spectroscopy graph between native starch and oxidized starch. Although the analytical results indicated that there were carbonyl and carboxyl production, characteristic vibrations of these groups exhibiting on IR spectra was not clear due to either not enough content of carbonyl and carboxyl groups or covering of strong other absorptions. Notwithstanding, IR spectra also shown the change of intensity of characteristic vibrations. Moreover, solubility of starch oxidized by the highest oxidant content level experienced highest degree while solubility of this starch shown the lowest level. It means that carboxyl in this molecule starch, to some extent, esterified with hydroxyl of either other starch molecules or glycerol to produce crosslink. The obtained results also illustrated that there was a little scission chain in oxidation process when modifying maize starch by sodium hypochlorite.
The effects of hypochlorite level, i.e. 0.5; 1 and 2 active chlorine g/100g starch, on the structures and physicochemical properties of oxidized maize starch were investigated. The obtained results shown that oxidation degree grew up with increasing hypochlorite concentration, specially, the carboxyl content saw higher increased than the content of carbonyl. SEM images indicated that surface of oxidized maize starches were rougher than native starch. The surface of oxidized starches saw rougher with increasing hypochlorite level. However, the DSC results illustrated that there was no significant difference of gelatinization temperature between the native starch and oxidized starches.
Effect of ZnO nanoparticles on nanocomposite coatings based on R4152 and graphene oxide (GO) was studied.In presence of 2%wt. ZnO nanoparticle, abrasion resistance of coating increased by nearly 25% (from 75 to 92.9 L/mil) and temperature decomposition raised by 18oC. SEM images showed that nano ZnO can disperse homogenously in polymer matrix in presence of GO. Hence, photocatalytic activity of R4152/GO/ZnO nanocomposite coating was higher than that of R4152/ZnO nanocomposite coating. After 14 hours UV exposure, R4152/GO/ZnO nanocomposite coating can degrade over 80% methylene blue coated on its surface while 60% methylene blue was degraded by R4152/ZnO coatings.
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