Surface Tension Modifiers

Suppliers include 3M, Akzo, Daniel, Henkel, and Rohm Haas. 

These are necessary in most, if not all, formulations if fungal attack in the can and, sometimes, of the dried film is to be avoided. Over the past few years, new products have come onto the market which are far less hazardous than the original materials, many of which were mercury derivatives and were toxic or harmful to humans and the environment. The modem products tend be non metal containing organic materials, which have low human toxicity. Addition levels will vary from product to product, but will mainly be in the region of 0.1-0.5%. 

If fungicides are not used, and fungal attack occurs, then the viscosity can drop and can seriously affect application and end properties. 

Suppliers include Akzo, Alfa, Dow Chemical, Hoechst and Thor. 

In most cases, the systems requite pH s in the range 8.0-10.0. If the pH is outside this range, then the stability of the finished product can be seriously affected and viscosities can change quite significantly especially if a pH sensitive thickener is being used. 

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Magnesium ferrosihcon alloys react vigorously when added to molten iron. As the magnesium vaporizes and cools, it reacts with residual surface tension modifiers such as sulfur and oxygen and greatly increases the surface tension of the molten iron. The dissolved graphite in the molten iron nucleates and grows into a spheroidal shape because of the increased surface tension of the molten iron. 

Chemical barrier — Chemicals that act as surface tension modifiers to inhibit the spread of an oil slick on water. When placed on the water surface next to an oil film, these chemicals push away the oil as a result of their surface tension. Chemical barriers work only with fresh oils, however, and their effect lasts only a few hours. (See also Surface tension.)... 

Fibrillation is also affected by the presence of compatibilizer. From the perspective of the capillarity parameter, k, addition of a surface tension modifier has two effects it lowers the... 

Lanco A1601 Lanco D2S surface tension modifier, themwplastic PVC... 

Fibrillation is also affected by the presence of a compatibilizer. From the perspective of the capillary parameter, k, addition of a surface tension modifier has two effects it lowers the interfacial tension coefficient (thus increasing k) and decreasing the initial drop diameter (thus increasing k) - the net result is difficult to predict. An illustration is provided in Fig. 7.30. Here PP drops in PA-6 matrix were observed during shearing in a cone-and-plate geometry, without and with an acrylic compatibilizer, AA. For both systems, the dimensions and short axes... 

Activation of the liquid lens was achieved by using a water soluble ferro-cenyl surfactant whose surface activity could be controlled electrochemically [27]. Application of a voltage difference across the lens produced a reversible reduction-oxidation process that modified the surface activity of the surfactant. The surface tension increased where oxidation occurred and decreased where reduction occurred with a magnitude of 8 d5m/cm. The total change in surface tension (16 dyn/cm) was more than one-fifth of the surface tension of pure water. This difference in surface tension modified the response of the system, resulting in a redistribution of the liquid. 

From Table 7-4 it can be seen that water will not wet Teflon, tinplate or steel but may wet glass. In order for water to wet the other substrates, the surface tension of the water must be reduced by the inclusion of surface tension modifiers, which are often termed wetting agents. 

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