【作者】 庄占兴；

【导师】 路福绥；

【作者基本信息】 山东农业大学 ， 农药学， 2009， 博士

【摘要】 本文对氟铃脲悬浮剂进行了配方筛选,并对该悬浮剂的形成稳定机理和不同因素对其流变性的影响进行了系统研究,同时对不同助剂加工的氟铃脲制剂的活性进行了比较。在测定不同种类分散剂HLB值和流点基础上,对粒径、粘度、表面张力等进行全面测定和比较,确定MOTAS和NNO为加工氟铃脲悬浮剂的优良分散剂,其最佳用量在3%左右。同时对增稠剂、防冻剂、消泡剂等进行了系统筛选,最后确定20%氟铃脲悬浮剂型优选配方为:氟铃脲20%;润湿分散剂(NNO或者MOTAS)2.5-3%;增稠剂黄原胶0.2%;防冻剂乙二醇2%;消泡剂:0.1%;水补足。根据上述配方分别加工成20%氟铃脲悬浮剂,其性能均达到常规农药悬浮剂所要求的控制指标,但从贮存前后粒径、悬浮率、析水率、粘度等指标的变化结果看,以MOTAS作为分散剂加工的20%氟铃脲悬浮剂的性能优于以NNO作为分散剂加工的20%氟铃脲悬浮剂。在氟铃脲悬浮剂加工的基础上,测定了两种分散剂在氟铃脲颗粒表面吸附方面的差异,探讨氟铃脲悬浮剂的形成和稳定机理,结果表明:氢键是分散剂分子与氟铃脲表面结合的重要作用力,且聚羧酸类分散剂MOTAS比萘磺酸类分散剂NNO的氢键力作用更加明显。随着分散剂分子量的增大,两种分散剂在氟铃脲表面的饱和吸附量分别增大,但NNO分散剂在氟铃脲表面的饱和吸附量比MOTAS明显偏小,两者的饱和吸附量分别为4.623mg.g-1、5.943mg.g-1。从吸附状态来看,两种分散剂在氟铃脲表面的吸附状态介于垂直与水平之间,属于弯曲状的多点吸附,其中NNO分散剂更接近水平状态。MOTAS、NNO作为阴离子表面活性剂吸附在氟铃脲颗粒表面,增大了氟铃脲颗粒的负电性,其中吸附了MOTAS电位明显高于吸附了NNO的电位,MOTAS产生的静电斥力明显大于NNO产生的静电斥力。NNO在氟铃脲表面达到吸附平衡的时间较MOTAS在氟铃脲表面达到吸附平衡的时间短,吸附速率快。MOTAS在氟铃脲表面的吸附层厚度为8.00nm,大于NNO在氟铃脲表面的吸附层厚度5.97nm,MOTAS在氟铃脲悬浮剂中产生的空间位阻明显大于NNO产生的空间位阻。分散剂吸附在氟铃脲颗粒表面后,由于分散剂的分子带有较强的负电荷,并且与水分子的氢键作用力较强,在分散剂吸附膜层外又形成水化膜,氟铃脲颗粒未吸附和吸附分散剂NNO、MOTAS后,形成水化膜的束缚水含量分别为1.99%、4.92%、7.12%,产生较大的空间位阻作用,也是使氟铃脲颗粒在水悬浮剂中保持稳定的因素之一。由上述原因,以MOTAS为湿润分散剂加工的氟铃脲水悬浮剂稳定性优于以NNO为湿润悬浮剂加工的氟铃脲水悬浮剂稳定性。通过采用五种流变模型对采用NNO、MOTAS分散剂制备农药悬浮剂的流变曲线进行拟合,最终确定用拟合相关系数R2最高的Herschel-Bulkley流变模型对实验中制备的农药悬浮剂的流变曲线进行拟合,研究了氟铃脲含量、分散剂种类用量、电解质种类用量、水的PH值等对氟铃脲悬浮剂的流变特性影响。对MOTAS和NNO分散剂制备的氟铃脲悬浮剂来讲,具有明显的“剪切变稀”特征,随着分散剂分子量的增大,屈服值降低,流动行为指数增大。在氟铃脲悬浮剂中,随着黄原胶含量的增加,粘度增加,屈服值τH变大,流动行为指数n变小,假塑性现象越来越明显,是良好的结构调节剂。冷贮和热贮两种贮存方式都能够使悬浮剂的粘度提高,但用MOTAS分散剂加工的氟铃脲悬浮剂变化小,其屈服值和流动行为指数基本稳定,而用NNO分散剂加工的氟铃脲悬浮剂变化较大,其屈服值和流动行为指数均明显增加,尤其是热贮后变成胀塑性流体。随着常温贮存天数增加,氟铃脲悬浮剂粘度逐渐增加,屈服值τH逐渐变大,流动行为指数n也逐渐变大。其中用NNO分散剂加工的氟铃脲悬浮剂变化较用MOTAS分散剂的变化大。植物叶面的性质、农药药液的性质及农药药液喷洒到植物叶面后与植物叶面形成的固、液、气三相的界面性质都将影响药液的持留效果。根据靶标临界表面张力的大小,可以预测不同表面张力的药液在植物靶标上的润湿、铺展状况,本试验测定了试验用甘蓝和棉花叶片的临界表面张力,其值分别为35.4mN/m、63.7mN/m。甘蓝叶面属于较难润湿的植物叶面,悬浮剂和乳油药液在80-100mg/L时即达到了最大持留,再增加浓度,持留量虽然有小幅增加,但增加幅度有限。棉花叶面属于较容易润湿的植物叶面,悬浮剂和乳油药液在40-60mg/L时即达到了最大的持留,再增加浓度,悬浮剂药液持留量仍然有小幅度增加,但增加不明显,而乳油药液在80mg/L时叶片持留量开始下降。药液的浓度并非越大越好,适当的浓度才能实现理想的持留。否则,将造成药液的流失,持留量下降。室内夹毒法测定氟铃脲不同剂型对小菜蛾三龄幼虫和棉大卷叶蛾三龄幼虫毒力基本没有差异,说明加工助剂没有引起氟铃脲毒力的变化,浸渍虫体法的毒力测定结果显示,乳油的毒力略高于悬浮剂的毒力,浸渍叶片法的毒力测定结果显示,悬浮剂药液浸渍甘蓝叶片对小菜蛾三龄幼虫的毒力略低于于乳油药液浸渍甘蓝叶片对小菜蛾三龄幼虫的毒力,悬浮剂药液浸渍棉花叶片对棉大卷叶螟三龄幼虫的毒力显著高于乳油药液浸渍棉花叶片对小菜蛾三龄幼虫的毒力,上述测定结果与药液在作物叶面的持留量呈正相关。因此,药剂加工时,不宜片面追求表面张力的降低,应该根据作物和防治对象进行适当选择。一般来讲,接触角越小,药液在植物叶面上的持留就会越好。但如果接触角过小,就会造成药液在植物叶面上的过于展开和润湿,形成过薄的药膜而流失,反而会减小持留。更多还原

【Abstract】 The pesticide formulations of hexaflumuron SC was selected ,and dispersion stabilization mechanism of the suspension, rheological behaviors of the system impacted by different factors were studied, and the activities of hexaflumuron agents with different additives were compared in this paper.Based on traditional selecting methods of suspension dispersants, particle size ,viseosity and surface tension of different dispersants were determined, and MOTAS and NNO were employed as excellent dispersants for hexaflumuron SC.The optimum amount of dispersants was around 3%. Moreover, thickening agent,Defoamer and antifreeze glycol were detected. The optimal formulations of hexaflumuron SC was as follow: hexaflumuron 20%,wetting dispersing agent (NNO or MOTAS) 2.5-3%, thickening agent xanthan gum 0.2%, antifreeze glycol 2%, Defoamer 0.1%, fill water to 100%.The product in all respects conformed to the requirements for a suspension concentrate. But Hexaflumuron SC processed with MOTAS had better property than that with NNO based on analysis in size, suspension rates, analysis of water rates,viscosity, and other indicators.Adsorption Characteristics of the two types of dispersants on the surfaces of hexaflumuron particles were determinated respectively,and the dispersion stabilization mechanism of the suspension was didcussed. The results showed that hydrogen bond was the main acting force between dispersant molecules and the surface of hexaflumuron, and the force of the hydrogen bonds of polycarboxylic acid type dispersing agent MOTAS was significantly higher than naphthalene sulfonic acid type dispersing agent NNO. The saturation adsorption amount of two dispersants increased respectively with increasing the vdispersants molecular weight, and the saturation adsorption amount of NNO on the hexaflumuron surface was lower than that of MOTAS obviously, 4.623mg.g-1 and 5.943mg.g-1 respectively. The adsorption conformation of the two types of dispersants on hexaflumuron surface were between trains and tails, dispersing agent NNO was closer to trains conformation. The negative of hexaflumuron particles was increased after adsorption MOTAS and NNO, and the potential of particles adsorption MOTAS was significantly higher than that NNO, and the electrostatic repulsion between MOTAS and hexaflumuron particles was significantly higher. The surface adsorption equilibrium time of NNO was shorter,and the adsorption rate was more rapidly. The adsorption layer thickness of MOTAS on the hexaflumuron surface was 8.00nm, greater than that 5.97nm of NNO. Because of a strong negative charge after adsorbed dispersant on the hexaflumuron surface and the strong hydrogen bonds, the hydration membrane was formated in the outer layer, Bound Water of hydration membrane with NNO , MOTAS and without these was 4.92%, 7.12%, 1.99% respectively, thus the high stability of the suspension was attributed to the electrostatic repulsion synergistically and the steric interactions. Therefore, the dispersion stability of hexaflumuron SC with MOTAS was higher than that with NNO.The rheological behaviors of hexaflumuron suspension were studied. The five rheological model were used to the curve fitting of the hexaflumuron suspension with NNO and MOTAS. The Herschel-Bulkley rheological model which was highest correlation coefficient R2 was determined to fit the rheological curve of pesticide SC. The effects on the rheological behavior of suspensions were studied, such as the content of hexaflumuron, the type and the content of dispersant dosage, the type of electrolyte, the pH value of water, and so on. The“shear-thinning”behavior were obvious in terms of hexaflumuron SC both with MOTAS and NNO. With the molecular weight of dispersant increasing, the yield values decreased, and the flow behavior index increased.With the content of xanthan gum increasing, the viscosity increased, the yield valueτH increased, the flow behavior index n decreased, and the pseudoplastic phenomenona was more obvious, and xanthan gum was structural adjustment.The viscosity of suspensions were increased through cold and thermal storage. The viscosity of hexaflumuron SC with MOTAS dispersant changed slightly, and its yield value and flow behavior index were almost maintains stable, but the viscosity of hexaflumuron SC with NNO dispersant changed significantly. in particularly, its yield and flow behavior index values were significantly increased, and it tend to bulging plastic fluid after thermal storage . The viscosity, the yield valueτH and the flow behavior index n of hexaflumuron SC were gradually bigger with the increasing the days stored at room temperature. The hexaflumuron SC with NNO dispersant were significant variations compared with MOTAS.The nature of plant leaves, pesticides liquid and the nature of the interface that pesticide liquid spraying to plants and plant leaf formation of solid, liquid, gas would influence the effects of the retention of liquid. According to the target critical surface tension, the wetting, spreading situation of the different of surface tension of the liquid on the targets would be predicted. The critical surface tension of the cabbage and cotton leaves tested in this research, the value were 35.4mN/m, 63.7mN/m respectively. The cabbage leaf surface which difficult to be wet, the maximum retention would obtain at 80-100mg/L liquid of hexaflumuron SC or EC, and then the concentration increasing, the quantity of retention was slightly increasing, but limited. The cotton leaf surface which more easy to wet, the maximum retention would obtain at 40-60mg/L solution of hexaflumuron SC or EC, and then the concentration increasing, the SC quantity of retention increased slightly, but the EC liquid retention declined. Therefor, the desired retention was attributed to appropriate concentration of the preparation, otherwise , the fluid would be loss, and the retention decrease..There was no difference in toxicity by testing the diamondback moth (Plutella xylostella) 3rd larvae and the cotton leaf roller (Syllepta derogata) 3rd larvae with three different formulations of hexaflumuron useing the leaf sandwich test, the results illustrated that the processing aids had no difference in toxicity among the formulations. The results of the dipping insects body test showed that the toxicity of hexaflumuron EC was slightly higher than hexaflumuron SC, and the toxicity of hexaflumuron SC is slightly lower than that of hexaflumuron EC for the diamondback moth (Plutella xylostella) 3rd larvae with the dipping cabbage leaf test, but the toxicity of hexaflumuron SC was significant higher than that of hexaflumuron EC with the dipping cotton leaf test for Syllepta derogata 3rd larvae, the above-mentioned results showed that there was positively correlated between the toxicity and the volume of fluid retention on plant leaf.Therefore, the appropriate selection of the liquid surface tension should be selected based on the crops and the control object of pesticide formulation processing, but not only reducd the liquid surface tension. The optimum liquid surface tension was slightly lower than the critical surface tension, the surface tension was too high, the liquid was difficultly to be wetted and spread on the target, and liquid had a serious loss; but the surface tension was too low, the liquid on the target was easy to expand and wet, the thinner film formated and the loss of liquid increased.更多还原