Waterproofing emulsion selection 1.Select emulsions bas […]
Waterproofing emulsion selection
1.Select emulsions based on the glass transition temperature of the polymer
The physical properties of polymers have an important influence on the properties of hardened JS waterproof coatings. The typical physical property of JS waterproof coating emulsion is its glass transition temperature. When the temperature is higher than Tg, the material behaves like a rubber and will be elastically deformed when loaded; when the temperature is lower than Tg, the material behaves like glass and it is easy to cause brittle failure. . The Tg value of the thermosetting polymer is relatively high, the Tg value of the elastomer polymer is low, and the thermoplastic polymer occupies between the two. The significance of the value of polymer emulsion for JS waterproof coating is that its elasticity or plasticity will affect the performance of the waterproof coating.
2.Select Emulsion Based on Lower Film Forming Temperature of Polymer
Another feature of the polymer is its lower film forming temperature, which is the lower temperature at which the polymer forms a continuous film. If the cement hydration temperature is lower than this value, the supplied energy is not enough to start film formation, and the polymer will exist in the water-repellent coating in the form of interrupted particles. Only when the hydration temperature of the cement is higher than the lower film-forming temperature of the emulsion, the emulsion can form a uniform membrane structure distributed between the hydration products so that it can act as a bridging function in the presence of stress and effectively absorb and transmit energy, thereby suppressing The formation and expansion of cracks. The polymer emulsion used for JS waterproof coatings should have a lower film formation temperature than the curing temperature.
3.Select emulsions based on the ionic stability of the polymer
The hydrates formed during the hydration of cement often contain active Ce, Al3 plasmas. The polymer emulsion must have high ionic stability. Otherwise, the polymer emulsion will fail due to demulsification. Therefore, the polymer emulsion for JS waterproof coating has high ionic stability. This can be achieved by controlling the combination of an anionic surfactant and a nonionic surfactant during the emulsion polymerization process. In general, anionic surfactants generally improve the mechanical stability of the polymer emulsion during emulsion polymerization, and non-ionic surfactants can improve the chemical stability of the emulsion. Therefore, the polymer emulsion for waterproof coating usually contains an appropriate amount of nonionic surfactant.