Sequential IPN Rubbery Modulus

Let us consider the Young s modulus, of a sequential IPN having both polymers above their respective glass transition temperatures. A simple numerical average of the two network properties results in  

An equation for a sequential IPN begins with a consideration of the front factor, where n represents the actual end-to-end distance 

If the network is unperturbed, the front factor is assumed to equal unity. For the case of perturbation via network swelling. 

For network I swollen with network II, the concentration of Pi chains is reduced to PiVi. Substituting this and equation (4.3) into equation (4.2), the contribution to the modulus by network I, Eu becomes 

With dilution of network II by network I, the contribution to the modulus by network II may be written 

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