I have some spectra obtained from plastics after a degradation process, the comparison was made with the pristine material and the results show in some cases greater intensity, bands that have moved and new bands in the fingerprint area. However, in some cases the literature is not clear on these issues (I see ambivalence in the reports, some say that the loss of bands is an unequivocal sign of degradation of the functional group, other authors say that any change seen is a sign of degradation), especially in degradation. I appreciate you can give me a clearer idea of how to interpret it.
In the case of polymers, changes in band intensity and shifts can typically be correlated with (micro)structural changes and mechanical properties variation, while the appearance and growth of new bands can be linked with the oxidation process. However, as far as I know, some of these processes are nonlinear.. so it can be tricky to follow the degradation pathways. Also, you have to keep in mind that FTIR has certain limitations in the evaluation of microstructural changes.. so coupled instrumentation is ideal.
Here are some basic resources that maybe can help you:
Edge M. (2006) Infrared Spectroscopy in Analysis of Polymer Degradation, https://doi.org/10.1002/9780470027318.a2013
Davidson R. (1992) Polymer Degradation Studies by FTIR, https://doi.org/10.1007/978-3-642-77636-6_10
Band changes in the infrared spectrum are related to the chemical structures present and the loss or formation of new structures. Shifts tend to be related to local environment around a given chemical structure (for a polymer the local morphology.) Remember that bands in the infrared are vibrational motions of local structures (functional groups/local modes). Degradation of a polymer can mean many things and you were not specific. When chains break you form new end groups, or when oxidation occurs you form new functional groups, etc.
There are many articles on band analysis in the infrared. Literature searches will lead you those specific to your problem. Dr. Cortea above has given you two to start with for your studey. Ioana Maria Cortea
- Badges
- Science topic