Migration of additives toward the surface during aging of epoxy coating by infrared spectroscopy

This research highlights the application of multi-angle attenuated total reflection (ATR) infrared (IR) spectroscopy method in investigating the migration of additives from the bulk toward the surface which happens in the epoxy coating. Concentration profiles of additives such as low molecular polyamide 651 (LMPA 651) and 2,4,6 - tris (dimethylaminomethyl) phenol (DMP-30) were studied. Analysis of the shape of the additives concentration profiles revealed the existence of enrichment region and indicated the migration phenomenon of additives in epoxy coating during natural aging and accelerated aging processes. The changes of the additives concentration determined by the ATR-IR method were consistent with the results obtained by FTIR analysis and gravimetric analysis. The result shows that the ATR-IR method is very promising for investigating the surface chemical changes in epoxy coating due to its nondestructive testing, conveniency, and high efficiency.