It is well known that methyl MQ silicone can be used as a reinforcing material for silica gel. It can be used alone or mixed with other reinforcing materials.
The main factors affecting the role of MQ resin are: M/Q ratio, group type, M/Q ratio. The solubility of MQ resin and silicone rubber will be affected, and the group type will affect the ionic bond strength between MQ resin and silicone rubber, and then affect the physical properties of silicone rubber.


A) influence of M/Q ratio
Methyl MQ silicone resins have different separation states in silicone rubber. The separation degree of MQ silicone changes significantly with the change of M/Q. When the M/Q ratio is 1.0, MQ silicone and rubber are completely dissolved, and no microscopic phase separation structure can be seen between them. When M/Q is 0.8, there is a significant microphase separation between MQ silicone resin and rubber. Rubber is the continuous phase, MQ silicone is the dispersed phase, and the size of the dispersed phase is small (about 5nm) and relatively uniform. When M/Q is 0.6, the size of the dispersed phase increases significantly and is very uneven. The size of the dispersed phase is about 50nm. In order to achieve good strengthening effect, moderate phase separation is necessary, so the M/Q ratio of 0.8 is usually better.


B) Influence of group type
For the condensation silicone rubber, the hydroxyl group affects the degree of chemical fusion between silicone resin and silicone rubber. With the increase of the hydroxyl group, the degree of chemical fusion between silicone resin and silicone rubber will be strengthened, while the solubility of the two will be weakened. The appropriate hydroxyl mass fraction can achieve a better strengthening effect. For the added formed RTV silicone rubber, MQ silicone resin with vinyl has a very good solubility and dispersion. MQ resin has a small molecular weight, and the dense vinyl can crosslink with the crosslinking agent by silicohydric addition reaction, and then form a firm chemical fusion with silicone rubber to improve the mechanical strength of silicone rubber.
C) influence of the amount of methyl MQ silicone used
The influence of the amount of resin used on the reinforcement effect is different in different literature reports, but in general, the corresponding reinforcement effect can only be achieved when the amount of resin used reaches the corresponding degree. The reasons for strengthening MQ resin can be explained as follows: With the increase of the use of vinyl MQ silicone resin, the crosslinking density of silicone rubber increases, the crosslinking tends to be sound, and the physical properties are gradually improved, but when the crosslinking density is too high, the physical properties decrease. This is because when the material is subjected to external force, the stress can be evenly separated to many molecular chains according to the centralized intersection point, so that the ability of the material to resist external force is strengthened, and the strength is improved; However, when the crosslinking density is too high, the distribution of crosslinking points is very uneven. Under the action of external forces, the stress is easy to concentrate on a small part of the network chain, resulting in the reduction of rubber elongation at break.