Determination of Critical Chain Length

Let the mole fraction of the total H-monomer in the H/D copolymer (random copolymer) be X, the mole fraction F of the H-monomer in the chain that consists of m consecutive monomers is 

The solid and broken lines indicate infrared bands perpendicular and parallel to the chain axis, respectiv.  

The integrated intensity of the band I(X) from the critical chain length m, which is measured under high conformational order is 

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