聚合物分散剂对氟铃脲水悬浮剂流变性质的影响

采用控制应力流变仪研究了聚合物分散剂苯乙烯丙烯酸无规共聚物（MOTAS）用量、分子量及氟铃脲质量分数等对氟铃脲水悬浮剂流变性质的影响。 结果表明，以聚合物MOTAS为分散剂制备的氟铃脲水悬浮剂的流变行为符合Herschel-Bulkley模型。 在固定氟铃脲质量分数为20%时，当分散剂质量分数≤3.0%时，流动行为指数n≤1.0，悬浮体系表现为假塑性流体，当分散剂质量分数≥3.5%时，流动行为指数n≥1.0，悬浮体系具有胀塑性流体特征。 氟铃脲水悬浮剂的流变参数屈服值τH与分散剂MOTAS和氟铃脲的加入量有关。 分散剂MOTAS质量分数≤2.5%时，分散剂在氟铃脲颗粒界面吸附很少，裸露的氟铃脲颗粒界面间相互搭接，具有较大的屈服值τH；当分散剂加入质量分数为3.0%时，分散剂可在氟铃脲颗粒界面形成饱和吸附，若再增加分散剂用量，多余分散剂在悬浮的氟铃脲颗粒间形成搭接，使其屈服值τH增大。 在MOTAS分散剂的分子量在10 000~30 000范围内时，MOTAS分子量愈大，所制得的氟铃脲水悬浮剂的表观粘度和屈服值τH愈小，流变行为指数n虽略有增加，但均小于1，没有改变“剪切变稀”的假塑性特征。

Effect of Polymer Dispersant on Rheological Properties of Hexaflumuron in the Form of Aqueous Suspension Concentrate

The rheology of hexaflumuron in the form of aqueous suspension concentrate(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 τ_H 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 τ_H. 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 τ_H likewise. Between dispersant MOTAS molecular mass 10 000 and 30 000, with the increase of MOTAS molecular mass, the viscidity and yield value τ_H 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.