Surfactants - Temperature influence on surface tension
The effects that surfactants have on the surface tension are temperature dependent.
The surface tension of liquids and the influence of surfactants on the surface tension depend on the temperature. Additionally, the dynamic of surfactant molecules increases due due higher thermal energy. In general, the surface tension decreases with increasing temperature.
As a result, the characteristics of surfactant containing liquids are significantly influenced by temperature changes. Depending on the product, the temperature influence can have a positiv or negative effect on required characteristics. In order to prevent negative changes, it is essential to add additional surfactants or dilute the solution respectively.
In any case, it is very important to know how the surface tension is influenced by changes of temperature.
At a certain temperature non-ionic surfactants in water are not soluble any more and form a phase with high number of surfactants. Due to those droplets the solution gets cloudy. This certain point of temperature called cloud point or phase reversal temperature is characteristic for non-ionic surfactants. The cleaning efficiency of non-ionic surfactants and surfactant systems improves the closer the process is operated to the cloud point. The cloud point can be adjusted according to the desired operating temperature using adequate additives.
The tensiometer of SITA Messtechnik GmbH allow easy analysing of such temperature-dependencies in research and development and product or process optimization.
The surface age, more precisely the bubble lifetime is adjusted to a fixed value allowing a permanent
measurement of the surface tension with changing temperatures. Thus, the influence of the surface age (interface liquid-air) on the surface tension can be neglected.
This enables a continuous measurement of the temperature influence on a surfactant solution with constant parameters.
A double walled glass vessel with a thermal liquid circulation allows an automatic measurement of the surface tension's development in relation to the temperature. Therefore, the test results provide valuable information for research and development in order to ensure an optimal adoption of the products to the according field of application.