【作者】 陈甜甜；

【导师】 路福绥；

【作者基本信息】 山东农业大学 ， 农药学， 2011， 博士

【摘要】 随着人类对农药化学品环境相容性要求的不断提升,农药水悬浮剂以其安全、高效等诸多优点成为绿色化学所倡导的农药制剂之一。本文以除虫脲为研究载体,在润湿分散剂筛选的基础上,系统研究了不同因素对农药水悬浮剂体系的分散稳定性和流变行为的影响,探讨了其相关机理。同时制备了Mg-Al MMH,并首次将其作为触变剂应用到农药水悬浮剂中,研究了不同Mg-Al MMH含量、电解质种类和浓度及温度对体系流变性的影响,探讨了Mg-Al MMH在除虫脲水悬浮剂中的触变性机理。主要研究结果如下:1.润湿分散剂的筛选是悬浮剂配方筛选的核心。通过流点法、平均粒径测定、Zeta电势测定三种润湿分散剂筛选方法的综合比较,结果表明:（1）三种方法各有特点同时具有一定相关性:a.流点法适用于任何种类润湿分散剂的筛选,筛选速度快,但筛选精确度较差,可作为润湿分散剂初步筛选方法;b.粒径测定可以准确确定合适的分散剂种类,适合各类润湿分散剂的筛选;c.Zeta电势的测定适合筛选阴离子型润湿分散剂,与粒径测定筛选结果相一致。（2）采用粒径测定、Zeta电势测定及黏度曲线法确定润湿分散剂的含量,三种方法具有较好的相关性。（3）对于20%除虫脲水悬浮剂,筛选结果为:润湿分散剂MOTAS:700# = 4:1,用量2%。（4）热重分析法进一步验证了采用非离子润湿分散剂和阴离子润湿分散剂复配能够起到更好的分散效果。2.通过IR谱图和吸附等温线的测定研究了分散剂MOTAS在除虫脲颗粒表面的吸附特性,结合平均粒径和Zeta电势的测定研究了除虫脲水悬浮剂的分散稳定性,研究结果表明:（1）IR谱图表明MOTAS以氢键结合力的方式吸附在除虫脲原药颗粒表面,同时通过静电排斥和空间位阻作用保持悬浮剂的分散稳定性。吸附等温线的测定表明,分散剂吸附量随着聚合物浓度增加而增大直至达到饱和吸附,等温吸附曲线近似Langmuir吸附模型。在相同条件下,分散剂相对分子量越大,原药颗粒表面的饱和吸附量越大;pH值影响聚合物分散剂的电离,随着pH值的增大,饱和吸附量降低;温度升高,饱和吸附量降低。（2）分散剂加入量过多或过少均会使分散稳定性下降,其最佳用量为2%;分散剂相对分子量越大,原药颗粒间的静电排斥力和空间位阻作用越大,分散稳定性增强;pH影响聚合物分散剂的电离,当pH值为9时,悬浮体系的分散稳定性最好;电解质的加入会破坏体系分散稳定性,且对于同浓度的一价Na⁺,二价的Ca²⁺压缩双电层的能力更为明显,使体系的分散稳定性明显变差。3.通过流变曲线的测定和稳态剪切法研究了添加MOTAS、MT所制备的除虫脲水悬浮剂的流变特性,探讨了体系的流变性机理。研究结果表明:（1）除虫脲水悬浮剂为“剪切变稀”的非牛顿流体,符合Herschel-Buckley流变模型。MT的加入可以使水悬浮剂产生一定的触变性,随着蒙脱土含量的增加,体系的流变参数和触变程度相应增加。（2）随着分散剂含量的增加,水悬浮剂的流变参数先增加后减小,但分散体系的触变程度随分散剂的含量的增加而减弱,当分散剂含量为2%时,体系有较好的流动性,且有一定程度的触变性。（3）体系的pH值不影响其流体类型和正触变性,但对除虫脲颗粒表面电荷和MT粒子间的作用力均有较大影响,二者的综合效应使得体系的流变参数和触变程度随pH的增大呈现出先减小后增大的趋势,当pH值在8⁹之间时,有一定的触变性,且体系流动性最好。电解质的加入不改变体系“剪切变稀”的假塑性特征和正触变性。（4）不同浓度的电解质对除虫脲水悬浮剂体系的影响取决于电解质对体系中原药颗粒表面电性和MT粒子表面电性的影响。随着电解质浓度的增加,体系的流变参数和触变性呈现出先增大后减小又增大的趋势,且同一浓度的NaCl和CaCl₂相比,CaCl₂对体系流变性的影响更为显著。（5）温度对分散剂在原药颗粒表面的吸附量影响较大,从而影响水悬浮剂的流变性。温度的升高不改变体系“剪切变稀”假塑性特征和正触变性,但除虫脲水悬浮剂的流变参数随着温度的升高而升高,当温度升高到55℃时,体系的触变性程度降低。4.采用液相共沉淀法制备Mg-Al MMH溶胶,并利用流变曲线和触变性测定研究了其在除虫脲水悬浮剂中的作用,结果表明:（1）XRD谱图表明颗粒具有水滑石晶体结构。（2）Mg-Al MMH作为触变剂应用于除虫脲水悬浮剂能够产生较好的正触变性,且制备的悬浮体系符合“剪切变稀”的假塑性流体类型。体系的流变参数和触变性随Mg-Al MMH的含量的增大而增大,Mg-Al MMH与吸附了分散剂后带负电的原药颗粒通过静电引力形成空间网状结构。（3）在一定的温度范围内,体系的流变参数随温度的升高而增大,但不影响体系“剪切变稀”假塑性特征和正触变性。（4）电解质的加入不改变体系“剪切变稀”假塑性特征及正触变性。随着电解质浓度的增加,体系的流变参数和触变性呈现出先增大后减小又增大的趋势,对于相同浓度的NaCl和CaCl₂,CaCl₂对体系的影响更为显著。更多还原

【Abstract】 With the increasing requirement of pesticide chemicals to environmental compatibility, pesticide water suspension concertration with many advantages such as safety and high effectiveness has been one of the important represents in pesticide formulation that green chemistry initiated. This thesis had chosen Diflubenzuron as the research object, on the basic of the selection of the wet dispersant, we did more research systemicly about the effects of different facts on the dispersed stability mechanism and rheology of pesticide suspension concentrate system, and probed into the related mechanism. We also prepared Mg-Al MMH and applied it to pesticide suspension concentrate as thixotropy. The influences of mass fractions of Mg-Al MMH（ω） , electrolytes concentration and temperature on the rheology of the system and Mg-Al MMH on the thixotropy mechanism of Diflubenzuron SC were studied in this paper.The main researches were following:1. The selection of the wet dispersant was the core during the selection of SC prescription process. The result after compositely comparing of such three methods （drop-point, average size and Zeta potential.） in dispersant selecting showed that :（1） The three methods had thire own characters respectively and certain correlate at the same time. a. The drop-point method which was fit to selection among any dispersants was a quick selecting progress. However, it was a premilinary selection method because of its poor accurate. b. The suitable dispersant could be determined exactly after particle size determination, and this method could be applied to the selection of any species dispersants. c. The method of Zeta potential which was aggrement with the selection result of particle size determination was fit to the selection of ionic dispersant.（2） The methods of average size, Zeta potential and viscosity curve determined the content of dispersant. They had better correspondence.（3） The selection result for 20% Diflubenzuron SC was MOTAS:700# = 4:1 with the total conent of 2%.（4） Non-ionic wet dispersant combined with ionic wet dispersant playing better dispersion was further verified by thermogravimetric analysis（TG）.2. The adsorption behaviour of dispersant MOTAS on the interface of Diflubenzuron particles was studied by the measurement of IR spectrogram and adsorption isotherm. The dispersion stability of Diflubenzuron SC was studied by average size and Zeta potential. The result showed that:（1） The IR spectrogram showed that MOTAS adsorded on the interface of Diflubenzuron particles by hydrogen bonding, and the dispersed stability of SC was keeped by electrostatic repulsion and steric hindrance effect. The result of adsorption isotherm showed that the adsorption capacity increased with the polymer concentration increasing until it reached saturation, and the adsorption isotherm was correspond with Langmuir equilibrium. The more dispersant molecular weight, the bigger saturated adsorption capacity of the interface of the technical material particles, and the saturated adsorption capacity decreased with the pH value increased which the pH value effect the ionization of polymer dispesant, and the saturated adsorption capacity decreased with the temperature increased under the same conditions.（2） The dispersion stability decreased with excessive or shortage dispersant which the optimal content is 2%, and the dispersion stability increased with bigger molecular weight of dispersant and bigger electrostatic repulsion and steric hindrance of original particles, and the pH value effect the ionization of polymer dispesant. At the pH value of 9 the dispersion stability of suspension concentrate was best. The addition of electrolytes could destroy dispersion stability, and the ability of compressing double-layer of monovalent Na⁺ was more distinct than bivalent Ca²⁺ when they were at the same concentration, and it decreased the dispersion stability more distinct.3. The prepared Diflubenzuron SC with adding MOTAS and MT as auxiliary agent was studied by flow curve experiment and Steady Shear Method, and its thixotropic behavior was studied by stable shear experiment. The result showed that:（1） Diflubenzuron SC was non-newtonina fluid of“shear-thinning”, which correspond with Herschel-Buckley rheological model. SC had certain thixotropic behavior after the adding of MT, and the rheological parameters and thixotropic degree increased with the content of MT increasing.（2） The rheological parameters of SC decreased after increasing with the dispersant mass fraction increasing, while the thixotropic behavior of dispersion system decreased with the dispersant mass fraction increasing. The system had good fluidity and thixotropic behavior when the dispersant mass fraction was 2%.（3） The pH value didn’t have effect on the fluid pattern and positive thixotropy, while it had a great impact on the surface charge of Diflubenzuron particles and forces between particles of MT, the rheological parameters and thixotropic degree of the system had a trend of decreasing and then increasing with the increased pH value under the composite effects. When the pH value was between 8 and 9, the system had certain thixotropic and its fluidity was best. The property of rheogram“shear-thinning”of the pseudo-plasticity and positive thixotropy of the SC added with electrolytes were not changed.（4） The effects of electrolytes with various concentration on the Diflubenzuron SC system were dependented on the composite effects of two different surface potentials electrolytes exerted between technical material particles and MT particles. The rheological parameters and thixotropic behavior of SC had a trend of increasing and then decreasing and then increasing with the dispersant mass fraction increasing. The influences of CaCl₂ were more significant than NaCl at the same concentration.（5） Temperature had a big influence on the dispersant adsorption capacity of technical material particles. Therefore, Temperature effected the rheology of SC. As the temperature increased, the property of rheogram“shear-thinning”of the pseudo-plasticity and positive thixotropy of the SC were not changed . However, the rheological parameters of Diflubenzuron SC increased with increase of temperature. The thixotropic degree of SC decreased when the temperature reached 55℃.4. Mg-Al MMH colloidal was prepared by liquid co-precipitation method, the analysis of rheological curve and thixotropic behavior showed that:（1） The XRD spectrogram showed that the particles had a structure of hydrotalcite crystal.（2） Mg-Al MMH acted as thixotropic agent which was applied to Diflubenzuron SC had better positive thixotropy, and the prepared SC system corresponded the property of rheogram“shear-thinning”of the pseudo-plasticity. The rheological parameters and thixotropic behavior of SC increased with the increase of the mass fractions of Mg-Al MMH..The space network structure was formed by electrostatic attraction between Mg-Al MMH and technical material particles with negative charged which adsorbed dispersant. （3） The rheological parameters of Diflubenzuron SC increased with increase of temperature at a certain temperature range, but the property of rheogram“shear-thinning”of the pseudo-plasticity and positive thixotropy of the SC were not changed.（4） The property of rheogram“shear-thinning”of the pseudo-plasticity and positive thixotropy of the SC added with electrolytes were not changed, too. The rheological parameters and thixotropic behavior of SC had a trend of increasing and then decreasing and then increasing with the dispersant mass fraction increasing. The influences of CaCl₂ were more significant than NaCl at the same concentration.更多还原