Abstract:

The rheology of hexaflumuron SC was studied by means of controlled stress rheometer， with the particular emphasis on the effects of polymer dispersant MOTAS（Styrene-acrylic acid random copolymer）mass concentrations, molecular mass and hexaflumuron mass concentrations. It was found that the rheological behavior of hexaflumuron SC, which contained MOTAS, coincided with the Herschel-Bulkley rheological model. For a hexaflumuron mass concentration of 20%, the SC was pseudoplastic fluid and the flow behavior index n≤1.0 when the MOTAS mass fraction was less than 3.0%; the SC was bulging plastic fluid and the flow behavior index n≥1.0 while the MOTAS mass fraction was more than 3.0%. The yield value τH of hexaflumuron SC was correlated with the relative mass fractions of MOTAS and hexaflumuron. Little MOTAS was adsorbed on the hexaflumuron granule surface in its concentration≤2.5%, and the uncoverd granules were connected with each other in some structures, which resulted in the biggist τH. When MOTAS mass fraction was 3.0%, saturated adsorption was achieved on the granule surfaces. The excessive MOTAS connected with each other in some structures, which produced the biggist τH likewise. Between dispersant MOTAS molecular mass 10 000 and 30 000, with the increase of MOTAS molecular mass, the viscidity and yield value τH of hexaflumuron SC decreased, while the flow behavior index n increased slightly .The n values were all less than 1, and the property of “shear thinning” of the pseudoplasticity was not changed.

Key words: Hexaflumuron, MOTAS dispersants, rheology, yield value &tau, H, rheological behavior index n