Kolrausch-Williams-Watts relaxation

Broadness of the relaxation spectrum, as attested, for example, by the low value of the exponent p in the Kolrausch-Williams-Watt expression. 

As mentioned in Chapter 3, glassy relaxation processes are often associated with a fairly broad spectrum of relaxation times. A simple expression that describes this spectrum reasonably well over a wide range of time is the stretched exponential, or Kolrausch-Williams-Watts (KWW) expression (Kolrausch 1847 Williams and Watts 1970 Shlesinger and Montroll 1984) ... 

In the time domain, the a relaxation process of amorphous polymers is successfully described by the Kolrausch-Williams-Watts (KWW) relaxation function (equation (15)) where the parameter Pkww that takes in account the non-Debye character of the time decay leads to an asynunetric broadening of < )( ) at short times, which typically vary between 0.2 and 0.5. 

---