In order to achieve this ,we systematically fitted first two and then three linear regression regions to the data. All co-polymer samples that we examined exhibited regions that could be described by a linear relationship between temperature and terahertz absorption. We observed at least two, and in most cases three, such regions in the temperature range studied with characteristic transition points between them. These discontinuities are indicative of a change in the molecular mobility of the material. For each linear fit, the figures of merit for the fit were calculated and compared. By seeking the minimum mean squared error, we empirically identified the best linear fit to the data, the number of linear regions and the intersection points between neighbouring regions. The slope of the linear fit in each region and the transition temperature, as defined by the intersection point of two adjacent linear fit lines were determined.