Additive liquid silica gel is a kind of silicone material which is vulcanized into elastomer by polydimethylsiloxane containing vinyl as basic polymer, hydrogen containing silicone oil as crosslinking agent and crosslinking agent at room temperature or heating in the presence of platinum catalyst. Compared with condensed liquid silica gel, addition liquid silica gel has the advantages of no by-products, minimal shrinkage, deep vulcanization and no corrosion to the materials in contact.

In recent years, the improvement of mechanical properties and application development of additive liquid silica gel have attracted extensive attention. The effect of silica on the properties of addition liquid silica gel has been widely reported. Hydrogen containing silicone oil also has a great influence on the mechanical properties of addition liquid silica gel; At present, there are relatively few studies in this field.

Liquid rubber was prepared by using multi hydrogen containing silicone oil with the same viscosity and different mass fraction of active hydrogen as crosslinking agent, and vulcanized test pieces were made to determine its mechanical properties. When the mass fraction of active hydrogen in hydrogen containing silicone oil increased from 0.43% to 1.57%, the tensile strength of liquid adhesive increased from 4.7mpa to 6.1mpa, the shore a hardness also increased gradually, and the elongation at break decreased from 490% to 255%. This is because the viscosity of hydrogen containing silicone oil remains unchanged. With the increase of the mass fraction of active hydrogen, the molecular segments between the actual crosslinking points become shorter, and the strength, hardness and elongation of liquid rubber decrease; When the mass fraction of active hydrogen in multi hydrogen silicone oil increases from 0.75% to 1.57%, the change of tear strength is not obvious. This can be explained as follows: when the mass fraction of active hydrogen in multi hydrogen containing silicone oil rises to 0.75%, the Si-H bond in the molecular chain of crosslinker is relatively concentrated, and the resulting steric hindrance effect makes the effective crosslinking point of liquid glue increase not significantly, so that the tear strength of liquid glue changes less.

Hydrogen terminated methyl silicone oil with different viscosity was added to the basic formula of liquid rubber, and its effect on the mechanical properties of liquid rubber was discussed. With the increase of viscosity of hydrogen terminated methyl silicone oil, the elongation at break and tear strength of liquid adhesive gradually increased, while the tensile strength and shore a hardness gradually decreased. This can be explained as follows: with the increase of viscosity of hydrogen terminated methyl silicone oil, i.e. the growth of molecular chain, the molar mass of vinyl silicone oil increases after reaction with vinyl terminated silicone oil. When crosslinked with hydrogen containing silicone oil, the increase of molecular chain increases the elongation at break and reduces the tensile strength and hardness.