Chen gave a method of calculating the activation energy for cases whose order is not necessarily first or second but rather may be a non-integer value [1]. This method is again based on measuring the maximum and the half intensity temperatures. From the equation proposed by May and Partridge for the general order

(1)

where b is the order of the kinetics and s ? is the pre-exponential factor expressed in cm ^3(b?1)sec ^?1.

The solution of Eq.(1) is given by

(2)

where is in sec ^?1.

This equation can be rearranged using the condition at the maximum and then solved numerically by approximating the integral by a certain number of terms of the asymptotic series and using the iterative Newton-Raphson method.

The Chen s method consists of finding the temperature at the maximum, T _M , by computer calculations for given values of b, s, E, ?. The used values were

Once the value of T _M is found, the intensity I _M can be found by inserting the temperature at the maximum in Eq.(2) and using again the asymptotic series. The values T ₁, T ₂, the low and high temperatures of half intensity, can be calculated by solving numerically the equation

Using the asymptotic series for the integral approximation, Chen found

After that, the geometrical parameters of the peak, i.e. ?, ?, ?,