No abstract

In the present study a fluorescence technique and nine fluorescence probes have been applied to monitor the curing of polyurethanes. As the curing proceeds, the fluorescence emission bands of the probes exhibit hypsochromic shifts due to the increase in the environmental microviscosity. An intensity ratio method was developed, where ratios of the low- to high-intensity changes (LHIC) in the emission bands were used to determine the degree of the curing process. The method enables one to follow the changes in the polymer structure throughout the entire curing process and to obtain comparable results from different types of probes during the same curing process and is independent of the probes or the polymers. The technique can be applied to a variety of commercial and industrial polymers.

In this study the curing degree and the shelf life of an epoxy resin were monitored by a fluorescence method. Four extrinsic fluorescence probes, so-called TICT compounds, were used. An intensity ratio method was applied, in which ratios of the lowest and highest intensity changes in the emission bands are used to determine the degree of the isothermal curing. A smooth and in some cases a linear correlation was found between the fluorescence intensity ratio and the degree of the cure. The fluorescence technique and the ratio method enable the monitoring of the precuring and shelf life of the studied epoxy polymer.