Addition type liquid silica gel is a kind of organic compound which is made of vinyl-containing polydimethylsiloxane as base polymer, hydrogen-containing silicone oil as cross-linking agent, and vulcanized into elastomer at room temperature or by heating cross-linking agent in the presence of platinum-based catalyst. Silicon material. Compared with condensation-type liquid silicone, addition-type liquid silicone has the advantages of no by-products, minimal shrinkage, deep vulcanization, and no corrosion to materials in contact during the cross-linking and vulcanization process. In recent years, addition type liquid silica gel has become the fastest growing variety among all kinds of silica gel.

In recent years, the improvement of mechanical properties of addition-type liquid silica gel and its application development have received extensive attention. There have been a lot of reports on the effect of silica on the properties of addition-type liquid silica gel. Hydrogen-containing silicone oil also has a great influence on the mechanical properties of addition-type liquid silica gel; however, there are relatively few studies in this area at present.

Multi-hydrogen silicone oil with the same viscosity and different active hydrogen mass fraction was used as the cross-linking agent to prepare the liquid glue, and the vulcanization test piece was made to measure its mechanical properties. When the mass fraction of active hydrogen in the multi-hydrogen silicone oil increased from 0.43% to 1.57%, the tensile strength of the liquid adhesive increased from 4.7MPa to 6.1MPa, the Shore A hardness also increased gradually, and the elongation at break increased from 490 % dropped to 255%. This is because the viscosity of the hydrogen-containing silicone oil remains unchanged. With the increase of the active hydrogen mass fraction, the molecular segments between the actual cross-linking points become shorter, and the strength, hardness and elongation of the liquid glue decrease. When the active hydrogen mass fraction increased from 0.75% to 1.57%, the tear strength did not change significantly. This can be explained as: when the active hydrogen mass fraction of the multi-hydrogen silicone oil increases to 0.75%, the Si-H bonds in the molecular chain of the cross-linking agent are relatively concentrated, and the resulting steric hindrance effect makes the effective cross-linking point of the liquid glue. The increase is not obvious, so that the tear strength of the liquid glue changes less.

Hydrogen-terminated methyl silicone oil with different viscosity was added to the basic formula of liquid glue, and its influence on the mechanical properties of liquid glue was discussed. With the increase of the viscosity of hydrogen-terminated methyl silicone oil, the elongation at break and tear strength of the liquid adhesive gradually increased, while the tensile strength and Shore A hardness decreased gradually. This can be explained that with the increase of the viscosity of the hydrogen-terminated methyl silicone oil, that is, the growth of the molecular chain, the molar mass of the vinyl silicone oil increases after the reaction with the terminal vinyl silicone oil. The increase of the chain increases the elongation at break and decreases the tensile strength and hardness.