General derivation of the WLF equation from a fluctuation approach to the glass transition

In the frame of a fluctuation approach to the glass transition, it is shown from a scaling argument that the product δ In v δT (≈ 15 K for polymers) is invariant with respect to the temperature or frequency dependence of the glass transition in homogeneous amorphous substances. With the aid of a differential geometry method follows that the very existence of this invariance already determines the form of the lg v‐T‐curves.