Effects of naphthyl sulfonate formaldehyde condensation dispersant on the rheological properties of hexaflumuron suspension concentrate

In order to study the effect of naphthyl sulfonate formaldehyde condensation (NNO) on the rheological properties of hexaflumuron suspension concentrate (SC), and to facilitate its processing procedure, the rheology behavior of hexaflumuron SC prepared from with the variation of polymer dispersant NNO of different mass fractions, molecular weights and hexaflumuron mass fractions was studied by using the control stress rheometer. The results demonstrated that the rheological curve of hexaflumuron SC, which include NNO, coincided with the Herschel-Bulkley rheological model. The range of the NNO mass fractions and dosage affected the rheology property of hexaflumuron SC. With 3.0% NNO in mass fractions, the SC was pseudoplastic fluid. The flow behavior index (n) was less than 1.0 when the concentration of hexaflumuron was higher than 20%. The SC was bulging plastic fluid when the flow behavior index was higher than 1.0, while the hexaflumuron mass fractions were less than 15%. The yield value (τ_H) of hexaflumuron SC was correlated with the relative mass fractions of NNO and hexaflumuron. When the hexaflumuron mass fraction was too high, saturated adsorption was inhibited on the surface of hexaflumuron granule. Therefore the bare hexaflumuron granule surface overlapped with each other and formed structure with higher yield value. When the hexaflumuron mass fractions were moderate, saturated adsorption was achieved on the granule surface. When the hexaflumuron mass fraction was too low, the excess NNO can form a structure between the suspended granules of hexaflumuron and increase the yield value. Under this test conditions, the viscidity and yield value of the hexaflumuron SC decreased with the increase of NNO molecular weight. The flow behavior index was also increased slightly, however, it was still less than 1. The properties of "shear thinning" of the pseudo-plasticity did not change, which indicated that the molecular weight of NNO and its concentration were both influential factors to the hexaflumuron SC rheology. The results showed that the yield value τ_H and flow behavior index were higher in hexaflumuron SC with dispersant NNO than that with dispersant MOTAS under the same conditions.