Silicone rubber is one of the most important products of polysiloxane. It is linear polysiloxane with high molar mass before vulcanization but reticulated elastomer after vulcanization. It has excellent high and low temperature resistance, climate resistance, ozone resistance, arc resistance, electrical insulation, resistance to some chemicals, high air permeability and physiological inertia. The above characteristics are closely related to the type of raw gum, filler, vulcanizing agent, additive, coordination and vulcanizing method.
Silicone rubber according to its product shape and curing mechanism, be divided into the following types :
Silicone rubber according to vulcanization temperature, divided into high temperature vulcanization type and room temperature vulcanization type , according to shape and mixing way divided into mixed silicone rubber and liquid silicone rubber, according to its cross-linking reaction mechanism divided into organic peroxide initiation type, condensation reaction type and addition reaction type.
HTV silicone rubber is high molar mass linear polydimethylsiloxane based polymer , mixed with reinforcing filler and vulcanizing agent (organic peroxide), under heating and pressure, vulcanized into elastomer.
RTV silicone rubber is low molar mass linear hydroxyl dimethylsiloxane based polymer, mixed with multi-functional cross-linking agents, catalysts, fillers and additives, cross-linked into elastomer at room temperature.
The additive liquid silicone rubber is the polymer based on polysiloxane containing vinyl, with polysiloxane containing Si-H bond as the cross-linking agent, under the action of platinum catalyst, hydrosilylation addition reaction, cross-link into elastomer.
Silicone rubber appears until now, both in performance and application has great development. For example, the tensile strength of polydimethylsiloxane after vulcanization only 0.3-0.5MPa, through adding vinyl and phenyl, and improve the molar mass, use reinforcing filler or improve the mixing technology, now the tensile strength has exceeded 13MPa; In addition, the tear strength of silicone rubber in the early was 10KN/m, now it is 50KN/m. The current organic block and hybrid modified silicone rubber, oil resistance, solvent resistance and flame retardant were greatly improved, tensile strength will exceed 15MPa, tear strength will exceed 50KN/m.
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