ABSTRACT
As well as the process of network degradation also the internal variable qcs is time dependent, which can be formulated by using the evolution equation
q ecs cs
( )qcs− −
ν θ (1)
which also depends on the ageing temperature θ . Here Ecs and νcs are the material parameters and R represents the universal gas constant. The time dependent stress function of the network scission process can by calculated as follows (Johlitz et al. 2014)
P qcs11 11 01( )t 11 = − ( )dage⎡⎣ ⎤⎦ ( )11,P (2) where ε11 is the chosen strain and θ is the constant temperature. Using an analytic solution of the evolution equation (1) we obtain a time function
q ecs
csτ( )t,θ = − −
where τcs ( )θ represents the chemical relaxation time of the network scission process
cs( )θ = ⎛⎝ ⎞⎠− −1
. (4)
The parameter identification of network scission process takes place in two steps. In the first step, the chemical relaxation times of the network in a particular medium at two different constant temperatures are identified. The results are shown in Table 1. Subsequently, using equation (4) the parameters of the network scission process listed in Table 2 were identified.
