Light curing resin systems analysis

The cure of the free radical resin systems was conducted using high intensity UV LEDs. To ensure safety of the analysis system and to improve reproducibility of the data, our DSC system was modified further with respect to the experiments described above. Ideally, the modified system would be flexible to evaluation of many different light sources (1), and such that the light sources could be positioned reproducibly relative to the sample pans in the instrument (2). 

The principal techniques that have been used in resin cure studies are differential scanning calorimetry (DSC Chapter 7), photocalorimetry (Sections 11.3.1 and 11.3.2), dielectric thermal analysis (DETA Section 12.2.1) and dynamic mechanical thermal analysis (DMTA Section 8.3.2). Earlier differential photocalorimetry (DPC) instruments were based on a DSC instrument. However, these were only partially successful in the analysis of photocurable polymers. The failure to develop a completely adequate system has been the result of two factors. The first and most significant is the change in the intensity of the light with time of operation - as much as an 80% reduction in the first 100 hours of operation. The second reason for the limited success was the lack of data analysis software to convert raw data into easy-to-understand results that could be correlated with actual performance. 

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