High purity magnesium oxide has good sintering performance. Can achieve low temperature sintering, made of highly dense fine crystal ceramics or multi-functional magnesium oxide film, can be expected to develop for high temperature, high corrosion and other harsh conditions of the material.
Perfluoroalkyl surfactants with 7 to 8 carbons are equivalent to the surface activity of hydrocarbons with 11 to 12 carbons. The surface activity of potassium salts is higher than that of corresponding sodium salts.
Critical micelle concentration (CMC) value of some fluorocarbon surfactants
The effect of polar groups and additives on the activity of ionic fluorocarbon surfactants
There are many factors that affect the activity of surfactants, such as the structure of the hydrophobic group, the temperature and pressure of the system, the electrolyte in the solution and the polar group piano ptfe powder at the hydrophilic end of the surfactant. Because in the coating system, in addition to surfactants, there are various additives. In a specific coating formulation, if the surfactant is not selected properly, it will affect the quality of the final coating product, such as stability and effect. Here, we will briefly discuss the effects of polar groups and additives on the activity of ionic fluorocarbon surfactants.
Table 17-7 lists the surface tension data of perfluorooxamide type surfactants (CFa) 2CFO(CF 2), CON H(CH 2) sZ, and different polar groups Z. It can be found from the table that, in the case of the same hydrophobic chain, the surface activity of the hydrophilic end group Z will change significantly. For example, when n=1 and the concentration is 0.5%, the surface tension of Z is N+(CH3)al is 43.87mN/m, and when Z is changed to N+(CH 3) 2CHzCO 7, its surface tension is reduced to 21.86mN /m. These situations can all be attributed to the size of the polar group. The concentration and dispersion of the charge density and the tightness of the formation of the electric double layer, the size of the polar group and the length of the chain also reflect the balance of the hydrophilic and lipophilic groups. In addition, the tightness and looseness of the arrangement of the polar groups are related to the arrangement of the hydrophobic groups on the surface of the solution. For ionic surfactants, special consideration should be given to the charge repulsion of the polar groups.
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