Base polymer
The following two main linear polyorganosiloxanes containing vinyl are used as base polymers for additive forming liquid silicone rubber. Their molecular weight distribution is wide, generally from thousands to 100,000 to 200,000. The most commonly used base polymer for additive liquid silicone rubber is alpha, ω-divinyl-dimethylsiloxane. The molecular weight and vinyl content of the base polymer can change the properties of liquid silicone rubber.


Crosslinking agent
The crosslinking agent used for additive forming liquid silicone rubber is an organic polysiloxane with more than 3 Si-H bonds in the molecule, such as linear methylhydropolysiloxane with Si-H group, cyclic methylhydropolysiloxane and MQ resin with Si-H group. Most commonly used are linear methylhydropolysiloxanes of the following structure. It was found that the mechanical properties of silicone rubber could be changed by changing the hydrogen content or structure of the crosslinker. Li Zhichao compared the effects of different structures and different contents of crosslinking agent (hydrogen-containing silicone oil) on the properties of additive liquid silicone rubber, and found that the hydrogen content of crosslinking agent is proportional to the tensile strength and hardness of silicone rubber. Gu Zhuojiang et al. changed the synthesis process and formula to prepare hydrogen-containing silicone oil with different structure, different molecular weight and different hydrogen content, and used it as a crosslinking agent to synthesize and form liquid silicone rubber.


catalyst
In order to improve the catalytic efficiency of the catalyst, platinum-vinyl siloxane complexes, platinum-alkynyl complexes and nitrogen-containing compounds modified platinum complexes were prepared. In addition to the type of catalyst, its dosage will also affect the performance of liquid silicone rubber products. Yan, Nianping et al. studied the mechanism of how the amount of platinum catalyst affected the properties of silicone rubber, and found that increasing the concentration of platinum catalyst could promote the cross-linking reaction between methyl groups and inhibit the decomposition of the main chain.


Reaction inhibitor
It was found that the mass ratio of alkynyl alcohol inhibitor to platinum catalyst affected the non-isothermal vulcanization kinetics of the additive liquid silicone rubber system. The higher the mass ratio of acetynol inhibitor to platinum catalyst, the higher the vulcanization characteristic temperature of the additive liquid silicone rubber system. Liu Jin et al. prepared alkoxy silanized acetylene hydrosilylation inhibitor, which can not only prolong the scorch time of the additive liquid silicone rubber, but also smooth the surface of the sulfide. Lei Weihua et al. found that when dimethylhexynol and vinylcyclosiloxane were combined, liquid addition silicone rubber had the effect of prolongation of inhibition time, shortening of curing time, significant increase of torque and faster vulcanization rate.