杀虫剂药液中表面活性剂的临界胶束浓度及表面张力

采用国家标准GB 5 5 4 9 90的方法测定了 30种市售杀虫剂推荐剂量药液的表面张力值 ,用表面张力法测定了 30种杀虫剂药液中表面活性剂的临界胶束浓度 ,并测定了表面活性剂 885的临界胶束浓度及相同浓度不同气 液界面条件下表面张力的变化。结果表明 ,大多数杀虫剂常规使用剂量的药液中 ,表面活性剂的用量没有达到其本身的临界胶束浓度 (CMC) ,有些药剂的推荐浓度与表面活性剂达到临界胶束浓度时的药液浓度相差 10倍以上。当气 液界面扩大到一定程度时 ,将改变药液中表面活性剂的临界胶束浓度 ,增加溶液的表面张力。为了充分发挥药剂对害虫的防治效果 ,药液中表面活性剂的浓度必须大于临界胶束浓度。

Critical Micelle Concen tration and Surface Tension of Surfactant in Liquid Insecticides

The surface tension of 30 insecticides with conventional concentration was measured with the method in national standard(GB 5549 90)in laboratory and the critical micelle concentration(CMC) of surfactant of each insecticide was measured according to the change of surface tension of the insecticide.The CMC of surfactant 885,and the changes of the surface tension of the same concentration of 885 with the area of gas liquid were measured,too.The surfactant did not reach the CMC in most liquid insecticides with conventional concentration,and the concnetration of some insecticides was 10 times more than conventional concentration when the surfactant was the same as the CMC.The CMC was changed as the area of gas liquid was increased largely,at the same time,the surface tension was inhanced.For good effectiveness to pests,the concentration of surfactant in the liquid insecticides with conventional concentration must be more than the CMC.