不同增稠剂对农药可分散油悬浮剂稳定性的影响

为明确不同增稠剂对以矿物油为分散介质的油悬浮体系稳定性的影响,以12.5%丙炔·吡嘧(丙炔噁草酮·吡嘧磺隆)可分散油悬浮剂为对象,通过流变学和多重光散射方法,研究了有机膨润土、有机高分子和气相二氧化硅3类增稠剂单独使用及有机膨润土和其他两类增稠剂分别搭配使用对可分散油悬浮剂物理稳定性的影响。结果表明:所有样品的流动特性指数(n)均小于1,为假塑性流体,具有触变性。除有机膨润土和高分子增稠剂Atlox Rheostrux100组合使用时体系更符合Casson方程外,其余样品均更符合Herschel-Bulkley方程。单独使用时,有机膨润土对保证体系稳定的效果相对较好;Atlox Rheostrux 100和Atlox Rheostrux200两种高分子增稠剂的效果差别较大,其中Atlox Rheostrux 100效果更好,这可能是由分子结构差异造成;两种气相二氧化硅类增稠剂由于不能有效形成氢键,效果较差。将有机膨润土和有机高分子增稠剂组合使用时,体系的稳定性有所提升,其中有机膨润土869和Atlox Rheostrux 100组合使用效果更好,体系具有较高的黏度,且具有良好的触变性,物理稳定性优异;有机膨润土869和疏水气相二氧化硅R974组合使用时则效果没有明显的提升。研究表明,流变学和多重光散射两种方法均能较好地表征可分散油悬浮剂的物理稳定性;新型高分子增稠剂和有机膨润土具有协同作用,将二者合理组合添加能大幅提升可分散油悬浮剂的稳定性。

Effects of different thickeners on the stability of pesticide oil dispersion

In order to clarify the effect of different thickeners on the stability of oil suspension system with mineral oil as dispersion medium, 12.5% oxadiargyl + pyrazosulfuron-ethyl oil dispersion was used as the research object. The effects of three types of thickeners (including organic bentonite, organic polymer and gaseous silica) and organic bentonite used with other two types of thickeners on the physical stabilities of oil dispersions were studied by rheology and multiple light scattering methods. The results showed that the flow characteristic index (n) of all samples were less than 1, which was a pseudoplastic fluid with thixotropic properties. Except the combination of organic bentonite and organic polymer Atlox Rheostrux 100, the system was more in line with the Casson equation. While other samples were more in line with the Herschel-Bulkley equation. Organic bentonite has a relatively good performance to increase the stability of the system when used alone. Two kinds of organic polymer thickeners, including Atlox Rheostrux 100 and Atlox Rheostrux 200, had different performance. Atlox Rheostrux 100 had more significsant effect than that of Atlox Rheostrux 200, which might result from their different molecular structures. Two gaseous silica thickeners exhibited little effect, because they can’t form hydrogen bonds effectively. When organic bentonite used with other two types of thickeners, organic bentonite and organic polymer combination can improve the performance. Particularly, organic bentonite 869 and Atlox Rheostrux 100 combination was better than others, wich suspension system had high viscosity and good thixotropy, and excellent physical stability. However, organic bentonite 869 and hydrophobic silica R974 combination had no improvement. The results showed that both rheological and multiple light scattering can characterize the physical stability of the oil dispersion, and the novel orgainc polymer thickener and organic bentonite have synergistic effect, combination reasonable can greatly improve the stability of the oil dispersion.