An equation, describing crystallization kinetics, of the form: \[1 - \varphi _{c} = \rm{e}^{K\ t^{n}}\] where \(\varphi _{c}\) is the crystalline volume fraction developed at time \(t\) and constant temperature, \(K\) and \(n\) are suitable parameters. \(K\) is temperature dependent. According to the original theory, \(n\) should be an integer from 1 to 4, the value of which should depend only on the type of the statistical model; however, it has become customary to regard it as an adjustable parameter that may be non-integral.