To determine if PVC and U or its derivatives or related compounds are complexing, and if their Tgs are lower than that of neat PVC, Fourier-Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) observations were necessary. FTIR uses infrared radiation to identify unknown materials. This is reflected by the peaks seen in the spectra, which are associated with absorption of light of different wavelengths by the vibrations of specific functional groups . If any substantial differences are observed in the vibrational peak frequencies of PVC-complex samples when compared to, in our case, the vibrational peaks in neat PVC and neat U or U related compounds, this indicates that the PVC and U and/or U related compounds in the sample are intimately mixed and interacting and not just in a phase separated physical mixture.