Main properties of silicone sealant

1. Appearance

The appearance of the silicone sealant mainly depends on the dispersion of the filler in the base glue. The filler is a solid powder. After dispersion, it can be evenly dispersed in the base glue to form a fine paste. Sometimes, depending on the nature of the filler itself, it is not ruled out that there are very small amounts of slight fine particles, which are all acceptable normal phenomena. If the filler is not dispersed well, there will be a lot of coarse particles. In addition to the dispersion of the filler, some other factors will also affect the appearance of the product, such as the mixing of granular impurities. These situations are all considered to be rough in appearance. When coarse particles are found, they should be judged.

2. Hardness

Hardness refers to the hardness of the silicone sealant after it is completely cured and becomes a rubber body. It is one of the physical and mechanical properties of the product. Hardness refers to the ability of the material to resist the attempt of the material to scratch or press into its surface. The standard hardness value is tested by using a hardness tester to make a test piece according to the national standard method. The higher the hardness of the sealant, the stronger the rigidity of the surface sealant, but the less elasticity and flexibility; the opposite is true for a lower hardness. Therefore, the hardness of the sealant has a certain range of requirements according to actual needs.

3. Tensile strength

Tensile strength refers to the ability of a material to resist damage when subjected to tension. The tensile strength value is also tested according to the method specified in the national standard. Sealant must have certain strength requirements according to its use needs, especially structural adhesives, which clearly stipulate the minimum strength value in the national standard. Sealant with too poor strength cannot meet the use needs. However, it is not advisable to overemphasize the strength of the sealant and ignore the elasticity.

4. Elongation

Elongation refers to the percentage of the total elongation of the material when stretched to its original length. Silicone sealant with good elasticity will have a greater elongation. As the minimum requirement for elongation, the sealant must meet the requirements of elongation performance in the national standard.

5. Adhesion to the substrate

This is a very important performance of the sealant in actual use. The sealant must have good adhesion to the substrate in actual use before it can be used. A simple way to check the adhesion is to clean the substrate with an appropriate solvent or detergent and dry it, then apply the sealant on it. After the sealant solidifies, peel off the sealant by hand to observe the adhesion.