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. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40051.
A new method to detect the glass transition was used to investigate the effects of physical aging on the glass transition of polystyrene by Fourier transform infrared (FTIR) spectroscopy. The results showed that the onset point of the glass transition shifted to higher temperature with aging, but the end point didn't change. It was demonstrated that this method was of great use in determining the glass transition temperature of aged polymeric samples. For each aged sample, the four bands assigned to the vibrational modes of the main chain groups and the side groups of polystyrene showed the same transition regions, indicating that the main chain and the side groups were aging synchronously. The rates of increase of the relative peak areas for the four investigated bands during the glass transition decreased with aging with the increased rates of the relative peak areas for the two bands assigned to side group decreasing less than those of main chain, which seemed to indicate the dominance of the side group in aging process.
The effect of plasticizer o-terphenyl on the glass transition of polystyrene was investigated by Fourier transform infrared spectroscopy from a new aspect. The peak areas of four conformation insensitive bands as a function of temperature were studied, these being assigned to the vibrational modes of main chain groups and side groups of polystyrene. It was shown that the reorientation relaxation temperature of the main chain around glass transition was lower than that of the side groups when polystyrene was plasticized by o-terphenyl. It was explained on the basis of cohesional entanglements of polystyrene chains. The reorientation relaxation region of the side groups was nearly the same as the macroscopically observable glass transition region of polystyrene, implying that the glass transition process of polystyrene was dominated by the reorientation of side groups.
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