In this article

a constitutive model based on microscopic physical mechanism was established by introducing a strain amplification factor into the statistical model of rubber elasticity

which considering the effect of dangling chains. Some parameters which relating to the polymer network

such as average molecular weight (

M

c

) of chain segments with both ends attached to the network (network strands) and volume fraction (

Φ

) of network strands

were calculated using the molecular weight (

M

c

)

vinyl content (

wt

Vi

) of the polysiloxane and percent conversion (

q

) of vinyl groups. The primary strain amplification factor (

X

0

)

infinite strain limits of the amplification factor (

X

X∞

) and decay exponent (z)

which relating to the nanoparticles

were obtained by fitting the stress-strain data. The resulting fitting curves were in good agreement with the experimental data of both single and bimodal silicone rubber composites. The constitutive model based on microscopic physical mechanism could become the bridge connecting the macroscopic stress-strain behavior to the microscopic molecular structure parameters and our work could promisingly provide a basis for the performance improvement and optimization of silicone rubber.