The effect of fluorocarbon chain length on the physicochemical properties of surfactants at different temperatures
In this work,the effects of temperature(0～40℃)on physicochemical properties(surface activity,foaming property and spreading property)of three surfactants with different fluoro-carbon chain lengths were studied.The results show that with the increase of temperature,the critical micelle concentration(CMC)of the fluorocarbon surfactant increased,the surface tension(γCMC)decreased.And the longer the fluorocarbon chain of the surfac-tant,the stronger the micelle formation ability,in which the CMC of the FC8 surfactant solution was the smallest(0.23 mmol/L),and the γCMC value was the lowest(15.07 mN/m).At low temperature,the foaming ratio of fluorocarbon surfactant is the lowest(especially FC4 is only 3.70 times at 0℃),and the foam-ing ratio reaches the best(6.00～8.73 times)when the tempera-ture rises to 20℃.The surfactants achieve the best foaming ratio at a temperature of 20℃,and further heating has little effect on the foaming ratio.At the same temperature,the longer the fluoro-carbon chain,the larger the foaming ratio,and the foaming ratio of FC8 reached 8.73 times at 20℃.Moreover,the spreading coef-ficient(S)of fluorocarbon surfactant increases with the increase of temperature,and the change of S tends to be gentle when the tem-perature reaches 20℃,and the longer the fluorocarbon chain is conducive to reducing the consumption of surfactant per unit area and saving cost.It can be seen that low temperature has a great impact on the performance of short fluorocarbon chain surfac-tants,especially when the foaming ratio is too low to meet the use requirements.If it is used in aqueous film forming foam extin-guishing agent,it needs to be compounded to improve its use per-formance.
NETL
NSTL
万方数据
