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为研究分散剂萘磺酸盐甲醛缩合物(NNO)对氟铃脲悬浮剂流变性的影响,以指导该剂型的加工,采用控制应力流变仪测定了NNO的用量、分子质量及氟铃脲质量分数变化等因素下制剂的流变性。结果发现:以NNO为分散剂制备的氟铃脲悬浮剂的流变曲线符合HerschelBulkley流变模型;NNO的分子质量范围和用量会影响氟铃脲悬浮剂的流变性能。在固定NNO质量分数为3%的条件下,当氟铃脲质量分数≥20%时,流动行为指数(n)<1.0,悬浮体系表现为“剪切变稀”的假塑性流体特征;当氟铃脲的质量分数≤15%时,n>1.0,悬浮体系表现为“剪切增稠”的胀性流体特征。氟铃脲悬浮剂的流变参数屈服值(τ_H)与NNO和氟铃脲的相对加入量有关。当氟铃脲含量过高时,则NNO不能在氟铃脲颗粒界面形成饱和吸附,裸露的氟铃脲颗粒界面间相互搭接形成结构,因而具有较大的屈服值;当氟铃脲含量过低,则多余的NNO可在悬浮的氟铃脲颗粒间搭接形成结构,也使其屈服值增大。在试验条件下,NNO的分子质量愈大,所制备氟铃脲悬浮剂的表观黏度和屈服值愈小,流动行为指数虽略有增加,但均小于1,仍表现为假塑性特征。本研究结果表明:相同情况下,以萘磺酸盐甲醛缩合物(NNO)为分散剂制备的氟铃脲悬浮剂的屈服值和流动行为指数均高于以苯乙烯丙烯酸无规共聚物(MOTAS)为分散剂制备的氟铃脲悬浮剂。
In order to study the effect of dispersant naphthalene sulfonate formaldehyde condensate (NNO) on the rheological properties of hexaflumuron suspension to guide the processing of this formulation, the amount of NNO, molecular weight and hexaflumuron Mass fraction changes and other factors under the rheology of the preparation. The results showed that the rheological curves of hexaflumuron suspension prepared by using NNO as dispersant were in accordance with the Herschel-Bulkley rheological model. The molecular mass range and amount of NNO affected the rheological properties of the hexaflumuron suspension. When the mass fraction of hexaflumuron was ≥20%, the behavior of pseudoplastic fluid with flow behavior index (n) <1.0 and the suspension system showed “shear thinning” under the condition of fixed NNO mass fraction of 3% When the content of hexaflumuron is less than 15%, n> 1.0, the suspension system is characterized by a “shear thickening” dilatant fluid. The rheological parameter yield value of the hexaflumuron suspension (τ_H) is related to the relative addition amount of NNO and hexaflumuron. When the content of hexaflumuron is too high, NNO can not form a saturated adsorption at the hexaflumuron particle interface, and the exposed hexaflumuron particles interface with each other to form a structure and therefore have a larger yield value. When the content of hexaflumuron Low, then the excess NNO can be interspersed between the hexaflumuron suspended particles to form a structure that also increases the yield value. Under the experimental conditions, the larger the molecular weight of NNO, the smaller the apparent viscosity and yield value of the prepared hexaflumuron suspension, the slightly increased flow behavior index but less than 1, which still shows pseudoplastic characteristics. The results show that under the same conditions, the yield value and flow behavior index of hexaflumuron suspension prepared with naphthalene sulfonate formaldehyde condensate (NNO) as dispersant are higher than that of styrene-acrylic acid random copolymer (MOTAS ) Hexaflumuron as a dispersant.