The performance of methylphenyl silicone resins mainly depends on two factors: one is the R/Si mentioned above, and the other is closely related to the ratio of methyl and phenyl (CH3/C6H5). The influence of phenyl content on the performance of silicone resins is shown in the following table:
Effect of phenyl content on properties of silicone resins
Phenyl content (%)          0 20 40 60 80 100
Condensation rate            Fast -- -- -- -- -- -- -- -- -- -- slow
Film hardness                  Hard -- -- -- -- -- -- -- -- -- -- soft
Curing property                Thermosetting ------- thermoplasticity

The methyl in methyl silicone resin is all replaced by phenyl to get phenyl silicone resin, which is made of phenyl trichloro (or trialkoxy) silane by hydrolysis condensation. Phenyltrichlorosilane is hydrolyzed under specific conditions and then rearranged in equilibrium to obtain phenylsiloxane as the structural unit of the polymer, referred to as the silicon ladder polymer, this is a kind of trapezoidal polymer, has good comprehensive properties.
Silicon ladder polymer soluble in benzene, tetrahydrofuran, methylene chloride and other solvents, can flow into colorless, transparent, tough film, this polymer is more superior than ordinary organic silicon resin has damp and hot resistance, in the steam heat aging resistance, as well as in the air, almost tensile strength is about twice as many ordinary organic silicon resin, can reach 27.5 41.2 MPa, The most outstanding performance of silicon ladder polymer is its heat resistance, in the air heated to 525℃ before the start of weightlessness. The chemical structural defects of this trapezoidal polymer, such as uncondensed hydroxyl groups, branching, crosslinking, etc., have a great impact on the performance.