The main components of silicone sealant generally include base polymer (organopolysiloxane, referred to as 107 glue), fillers, plasticizers, cross-linking agents, catalysts and functional additives, etc. The structure and composition of these components will Impact on the performance of silicone sealants.
Among them, nano-calcium carbonate, which is the main filler of silicone sealant products, accounts for the highest mass proportion in most formula systems, so it has a particularly significant impact on the performance of silicone sealant products. Research shows that nano-calcium carbonate can not only fill and expand the silicone sealant system, but also play a reinforcing role, directly affecting the mechanical properties and application performance of the silicone sealant.
The crystal form of nano calcium carbonate should be compatible with the production formula of silicone sealant, product processing technology and equipment conditions. Generally speaking, cubes, rhombohedrons, and chain-shaped crystal forms with cubic parts have a wide range of adaptability.
Pressure bubble carbonization and high-shear emulsification modification processes were used to synthesize nano-calcium carbonate with similar grain size and different crystal shapes, and used it as a filler to prepare a one-component dealcoholized silicone sealant. The research on nano-carbonate Effect of calcium crystal shape on mechanical properties of silicone sealant and its mechanism of action.
test results
(1) The shape of nano-calcium carbonate crystals has a significant impact on the performance of silicone sealant products. The mechanism may be that the crystal shape affects the degree of dispersion, bulk density and steric hindrance of calcium carbonate particles in the silicone rubber system, resulting in The different modes of action and strength of the 107 molecular chains affect the density, curing rate, hardness, tensile strength and other mechanical properties of the silicone sealant.
(2) Different crystal forms of nano-calcium have different reinforcing effects on silicone sealants. Spherical and cubic-shaped nano-calcium are suitable for preparing silicone rubber products with low hardness, moderate tensile strength and high elastic recovery rate; while spindle-shaped nano-calcium And needle-shaped nano-calcium is suitable for preparing silicone rubber products with high hardness, high tensile strength and high dimensional stability.
(3) Nano-calcium carbonate of different crystal forms can be compounded to obtain nano-calcium carbonate products with more balanced filling properties, which provides a new idea for improving nano-calcium carbonate products and improving the performance of silicone rubber products.