Addition-type liquid silicone is a type of organic elastomer that is made of vinyl-containing polydimethylsiloxane as the base polymer, hydrogen-containing silicone oil as the cross-linking agent, and vulcanized into an elastomer at room temperature or by heating the cross-linking agent in the presence of a platinum catalyst. silicon material. Compared with condensation-type liquid silica gel, addition-type liquid silica gel has the advantages of no by-products, minimal shrinkage, deep vulcanization, and no corrosion to contact materials during the cross-linking 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 the mechanical properties of addition-type liquid silica gel and its application development have received extensive attention. There have been many reports on the influence 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; but there are relatively few studies in this area at present.

     The liquid glue was prepared by using multiple hydrogen-containing silicone oils with the same viscosity and different mass fractions of active hydrogen as the crosslinking agent, and made into vulcanized test pieces to measure their mechanical properties. When the mass fraction of active hydrogen in hydrogen-containing silicone oil increases from 0.43% to 1.57%, the tensile strength of the liquid glue increases from 4.7MPa to 6.1MPa, the Shore A hardness also increases gradually, and the elongation at break increases from 490 % down to 255%. This is because the viscosity of the hydrogen-containing silicone oil remains unchanged. With the increase of the mass fraction of active hydrogen, the molecular chain segments between the actual cross-linking points become shorter, and the strength, hardness and elongation of the liquid glue decrease; when more hydrogen-containing silicone oil When the mass fraction of active hydrogen 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 polyhydrogen-containing silicone oil rises to 0.75%, the Si-H bonds in the molecular chain of the crosslinking agent are relatively concentrated, and the resulting steric hindrance effect makes the effective crosslinking point of the liquid glue The increase is not obvious, so that the tear strength of the liquid glue changes little.
     Hydrogenated 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 the terminal hydromethyl silicone oil, the elongation at break and the tear strength of the liquid adhesive gradually increased, while the tensile strength and Shore A hardness gradually decreased. This can be explained as that, with the increase of the viscosity of the terminal hydrogen silicone oil, that is, the growth of the molecular chain, the molar mass of the vinyl silicone oil increases after reacting with the terminal vinyl silicone oil. The increase of the chain increases the elongation at break and decreases the tensile strength and hardness.

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